Biological Bases of Behavior: Nervous and Endocrine Systems (7A) - Psych & Soc

What is the primary neurotransmitter released by most sympathetic postganglionic neurons?

Norepinephrine. NE binds adrenergic receptors for sympathetic effects.
Which ANS division mediates "rest-and-digest" functions?

Parasympathetic nervous system. Promotes energy conservation and digestion when relaxed.
What is the primary function of the Na $^+$ /K $^+$ ATPase in neurons?

Maintains ion gradients across the membrane. Pumps 3 Na $^+$ out and 2 K $^+$ in, maintaining resting potential.
Which endocrine gland releases epinephrine and norepinephrine into the bloodstream?

Adrenal medulla. Part of sympathetic response, releasing stress hormones systemically.
Which PNS division controls skeletal muscle (voluntary) movement?

Somatic nervous system. Controls voluntary movements via motor neurons to skeletal muscles.
What is the main endocrine effect of thyroid hormones $T_3$ and $T_4$ ?

Increase basal metabolic rate. Regulate cellular metabolism and heat production throughout body.
What is the role of the Na+/K+ ATPase in neurons?

Maintains $\text{Na}^+$ and $\text{K}^+$ gradients using ATP. Pumps 3 $\text{Na}^+$ out and 2 $\text{K}^+$ in per cycle.
What are the two branches of the autonomic nervous system (ANS)?

Sympathetic and parasympathetic. ANS splits into opposing branches for homeostatic balance.
Which ion's efflux primarily causes the repolarization phase of an action potential?

K $^+$ efflux. K $^+$ channels open after Na $^+$ channels, restoring negative potential.
What ion influx is primarily responsible for the depolarization phase of an action potential?

Sodium ( $Na^+$ ) influx through voltage-gated sodium channels. Opening of $Na^+$ channels drives membrane toward positive.
What are the three major parts of a neuron?

Dendrites, soma (cell body), axon. These structures process, integrate, and transmit neural signals.
What is the immediate effect of parasympathetic activation on gastrointestinal motility?

Increases gastrointestinal motility and secretion. Enhances digestion when body is at rest.
Which autonomic division mediates "fight-or-flight," and what is its primary neurotransmitter at target organs?

Sympathetic; mainly norepinephrine at most target organs. Sympathetic activation prepares for stress responses, with norepinephrine binding adrenergic receptors to elicit effects.
Which ion influx primarily causes depolarization during a neuronal action potential?

Sodium ( $Na^+$ ) influx. Opens voltage-gated channels making membrane more positive.
Which ion influx primarily causes depolarization during an action potential?

Sodium ( $Na^+$ ) influx through voltage-gated channels. Opening of $Na^+$ channels makes membrane more positive.
What ion efflux is primarily responsible for the repolarization phase of an action potential?

Potassium ( $K^+$ ) efflux through voltage-gated potassium channels. Opening of $K^+$ channels returns membrane to negative.
What is the difference between gray matter and white matter in the nervous system?

Gray: cell bodies/synapses; White: myelinated axon tracts. Gray contains processing centers; white contains communication pathways.
What is the myelin sheath's main effect on action potential conduction?

Increases conduction velocity. Insulation allows action potentials to jump between nodes (saltatory conduction).
What are nodes of Ranvier, and what is their key role in signaling?

Myelin gaps enabling saltatory conduction. Action potentials jump between these unmyelinated segments.
What is the term for the myelin-producing cell type in the CNS?

Oligodendrocyte. Forms myelin sheaths around CNS axons for faster conduction.
Which brain region is the primary homeostatic control center linking nervous and endocrine systems?

Hypothalamus. Controls pituitary hormones and autonomic functions.
What is saltatory conduction?

Action potentials "jump" node-to-node along myelinated axons. In myelinated axons, action potentials regenerate only at nodes, enabling efficient, rapid transmission over long distances.
Which glial cell type myelinates axons in the central nervous system?

Oligodendrocytes. Each cell can myelinate multiple axon segments in brain and spinal cord.
What is saltatory conduction?

AP propagation by jumping between nodes of Ranvier on myelinated axons. Myelin insulation forces current to flow between gaps.
What is the primary function of the axon in a neuron?

Transmit action potentials away from the soma. It's the output structure that propagates electrical signals.
What type of feedback loop most commonly regulates endocrine hormone levels?

Negative feedback. High hormone levels inhibit further release for homeostasis.
Which pituitary lobe secretes tropic hormones such as TSH, ACTH, LH, and FSH?

Anterior pituitary. Produces hormones that regulate other endocrine glands.
What is the primary function of a neuron's axon?

Transmit action potentials away from the soma. The axon carries electrical signals from the cell body to terminals.
What is the major inhibitory neurotransmitter in the adult brain?

GABA. GABA opens $Cl^-$ channels to hyperpolarize neurons.
Which autonomic division is primarily responsible for "fight-or-flight" responses?

Sympathetic nervous system. Activates during stress: increases heart rate, dilates pupils, releases glucose.
Which hormone is released by the pineal gland to regulate circadian rhythms?

Melatonin. Secreted at night to promote sleep and regulate sleep-wake cycles.
What is the role of the pituitary gland in endocrine signaling?

Secretes hormones under hypothalamic control to regulate other glands. "Master gland" releases tropic hormones affecting target endocrine organs.
What are the glial cells that myelinate axons in the central nervous system?

Oligodendrocytes. Form myelin sheaths in brain and spinal cord.
What is the key functional difference between the somatic and autonomic nervous systems?

Somatic controls voluntary skeletal muscle; autonomic controls involuntary organs. Somatic is conscious control; autonomic is unconscious regulation.
What is the primary physiological effect of antidiuretic hormone (ADH)?

Increases water reabsorption in the kidneys. Conserves body water by reducing urine production.
Which endocrine gland releases $T_3$ and $T_4$ to increase basal metabolic rate?

Thyroid gland. Thyroid hormones increase cellular metabolism throughout body.
What is the major excitatory neurotransmitter in the brain?

Glutamate. Glutamate binds NMDA/AMPA receptors to depolarize neurons.
What are the three major parts of a typical neuron (by name)?

Dendrites, soma (cell body), axon. These structures receive, integrate, and transmit neural signals respectively.
Which neurotransmitter is classically associated with skeletal muscle contraction?

Acetylcholine. ACh binds nicotinic receptors at neuromuscular junctions.
Which autonomic division mediates "rest-and-digest," and what is its primary neurotransmitter at target organs?

Parasympathetic; acetylcholine at target organs. Parasympathetic promotes conservation and recovery, using ACh on muscarinic receptors for inhibitory actions.
What is the term for the myelin-producing cell type in the PNS?

Schwann cell. Forms myelin sheaths around PNS axons for faster conduction.
What is the primary neurotransmitter released by parasympathetic postganglionic neurons?

Acetylcholine. ACh binds muscarinic receptors for parasympathetic effects.
What is the absolute refractory period?

Interval when no new AP can be generated (Na $^+$ channels inactivated). Ensures unidirectional propagation of action potentials.
What is the key functional difference between sympathetic and parasympathetic divisions?

Sympathetic: fight-or-flight; Parasympathetic: rest-and-digest. Sympathetic activates stress response; parasympathetic promotes recovery.
What is the all-or-none principle of an action potential?

Once threshold is reached, AP occurs with fixed amplitude. Ensures reliable signal transmission regardless of stimulus strength.
Which ANS division is characterized by "rest-and-digest" responses?

Parasympathetic nervous system. Conserves energy and promotes recovery when relaxed.
What endocrine gland releases epinephrine as part of the acute stress response?

Adrenal medulla. Part of sympathetic response, releases catecholamines.
Which brain structure is primarily responsible for homeostasis and endocrine regulation via the pituitary?

Hypothalamus. Links nervous and endocrine systems through releasing hormones.
Which adrenal region secretes cortisol as part of the long-term stress response?

Adrenal cortex (zona fasciculata). Responds to ACTH stimulation during chronic stress.
What brain structure is the primary homeostatic control center linking to the endocrine system?

Hypothalamus. Integrates neural and hormonal signals, controls pituitary output.
Which ion efflux is primarily responsible for the repolarization phase of an action potential?

Potassium ( $K^+$ ) efflux through voltage-gated potassium channels. $K^+$ channels open later, restoring negative membrane potential.
Which endocrine gland secretes epinephrine and norepinephrine as part of the stress response?

Adrenal medulla. Modified sympathetic ganglion releasing catecholamines directly.
What structure allows saltatory conduction by separating myelinated segments?

Nodes of Ranvier. Unmyelinated gaps where action potentials regenerate.
What is the primary effect of an inhibitory postsynaptic potential (IPSP)?

Hyperpolarizes postsynaptic membrane, decreasing likelihood of firing. Makes membrane potential more negative, farther from threshold.
What is the direct effect of acetylcholine at the neuromuscular junction?

Binds nicotinic receptors and depolarizes the muscle end plate. Opens ligand-gated Na $^+$ channels causing muscle contraction.
What is the primary inhibitory neurotransmitter in the central nervous system?

GABA. GABA activates chloride channels, hyperpolarizing neurons to inhibit action potential generation.
Identify the neuron structure that receives incoming synaptic signals from other neurons.

Dendrites. Branch-like extensions that increase surface area for signal reception.
What is the function of the sodium-potassium pump in neurons?

Maintains gradients by pumping $3Na^+$ out and $2K^+$ in. Uses ATP to restore resting potential ion distribution.
What neurotransmitter is released by most sympathetic postganglionic neurons?

Norepinephrine. NE is the primary sympathetic neurotransmitter at target organs.
What is the neurotransmitter released by all autonomic preganglionic neurons?

Acetylcholine. Both ANS branches use ACh at ganglionic synapses.
Which neurotransmitter is most strongly associated with neuromuscular junction signaling?

Acetylcholine (ACh). ACh binds nicotinic receptors causing muscle contraction.
Which ion efflux primarily causes repolarization during a neuronal action potential?

Potassium ( $K^+$ ) efflux. Opens after $Na^+$ channels to restore negative potential.
What is the primary role of myelin in neural signaling?

Increases conduction velocity by insulating the axon. Prevents ion leakage, forcing signal to jump between nodes.
Identify the endocrine gland that secretes insulin and glucagon to regulate blood glucose.

Pancreas (islets of Langerhans). Beta cells secrete insulin; alpha cells secrete glucagon.
Which autonomic division is characterized by "rest-and-digest" physiology?

Parasympathetic nervous system. Conserves energy and promotes digestion when relaxed.
What is the primary function of the sodium-potassium pump at rest?

Maintains gradients by moving $3Na^+$ out and $2K^+$ in. Uses ATP to maintain resting potential of approximately -70mV.
Identify the ion movement that primarily causes depolarization in an action potential.

Voltage-gated $\text{Na}^+$ influx. Opening of channels makes membrane potential more positive.
What is the typical direction of information flow in a neuron?

Dendrites soma axon axon terminals. Signal travels from input region to output region unidirectionally.
What is the primary function of the somatic nervous system (SNS)?

Voluntary control of skeletal muscles; sensory to CNS. SNS controls conscious movements and relays sensory information.
Which ANS branch is associated with "rest-and-digest" physiology?

Parasympathetic nervous system. Promotes energy conservation and digestion when relaxed.
What is saltatory conduction?

Action potentials "jump" between nodes of Ranvier on myelinated axons. Rapid signal propagation by skipping myelinated segments.
What ion movement primarily causes the rapid upstroke of an action potential?

Na $^+$ influx through voltage-gated Na $^+$ channels. Rapid Na $^+$ entry creates a positive feedback loop, driving the membrane potential toward Na $^+$ equilibrium.
What is the primary function of dendrites in a neuron?

Receive incoming signals from other neurons. They're the input structures with receptors for neurotransmitters.
What type of receptor binds acetylcholine at the neuromuscular junction?

Nicotinic acetylcholine receptor. Ion channel receptor that triggers muscle contraction when activated.
Identify the neurotransmitter released by parasympathetic postganglionic neurons.

Acetylcholine. ACh binds muscarinic receptors for parasympathetic effects.
What is the main functional role of interneurons (association neurons)?

Integrate information within the CNS between neurons. They connect sensory and motor neurons for processing.
Identify the hormone that lowers blood glucose by increasing cellular uptake and glycogenesis.

Insulin. Promotes glucose storage when blood sugar is elevated.
Which autonomic branch is classically described as "rest-and-digest"?

Parasympathetic nervous system. Slows heart rate, constricts pupils, and promotes digestion.
Which nervous system division is primarily responsible for rest-and-digest functions?

Parasympathetic nervous system. Uses acetylcholine to slow heart rate, promote digestion.
What is the basic functional unit of the nervous system that transmits electrical signals?

Neuron. Neurons specialize in rapid signal transmission via electrochemical gradients, forming the foundation for nervous system communication.
What is the primary function of the autonomic nervous system (ANS)?

Involuntary regulation of glands, smooth and cardiac muscle. ANS operates without conscious control for internal organ function.
Identify the endocrine gland that secretes $T_3$ and $T_4$ to increase basal metabolic rate.

Thyroid gland. Thyroid hormones regulate metabolism and energy production.
What is the primary functional difference between the central and peripheral nervous systems?

CNS integrates/processes; PNS carries signals to and from CNS. CNS is the brain/spinal cord; PNS is all nerves outside CNS.
Which neurotransmitter is most strongly linked to reward and motivation pathways?

Dopamine. Key player in addiction and Parkinson's disease.
What is the immediate ionic cause of the depolarization phase of an action potential?

Voltage-gated $Na^+$ channels open; $Na^+$ influx. Rapid sodium entry makes the inside of the cell more positive.
What is the primary function of the peripheral nervous system (PNS)?

Transmits signals between CNS and body. Nerves carry sensory and motor information to/from the CNS.
What is the primary endocrine function of the anterior pituitary gland?

Secretes hormones in response to hypothalamic releasing hormones. Acts as relay between hypothalamus and target glands.
Which adrenal region secretes epinephrine and norepinephrine during acute stress?

Adrenal medulla. Functions as modified sympathetic ganglia releasing catecholamines.
Identify the process by which neurotransmitter is released into the synaptic cleft.

Calcium-triggered vesicular exocytosis. $Ca^{2+}$ influx causes vesicles to fuse with membrane.
What is the main distinction between endocrine and nervous signaling?

Endocrine: hormones in blood; nervous: electrochemical synapses. Speed differs: hormones are slower but longer-lasting.
What is the resting membrane potential of a typical neuron (approximate value)?

Approximately $-70\ \text{mV}$ . Maintained by Na $^+$ /K $^+$ pump and ion permeability differences.
What is the definition of an excitatory postsynaptic potential (EPSP)?

Postsynaptic depolarization increasing firing likelihood. Makes membrane potential less negative, closer to action potential threshold.
What is the primary function of the somatic nervous system?

Voluntary control of skeletal muscles and somatic sensory input. Somatic means voluntary; controls conscious movements and sensations.
Which glial cell myelinates axons in the central nervous system (CNS)?

Oligodendrocytes. Each oligodendrocyte can myelinate multiple CNS axons.
What neurotransmitter is released by parasympathetic postganglionic neurons?

Acetylcholine. ACh activates parasympathetic target organs.
Identify the neurotransmitter most associated with neuromuscular junction signaling.

Acetylcholine. Binds nicotinic receptors to trigger muscle contraction.
What is the synapse, and where do neurotransmitters act?

Junction where neurotransmitters bind receptors on the postsynaptic membrane. Synapses facilitate chemical communication, with neurotransmitters modulating postsynaptic excitability via receptor binding.
What is the all-or-none principle for action potentials?

AP occurs only if threshold is reached; size is constant. Like a light switch - either fully on or off, no in-between.
What is the main effect of cortisol released from the adrenal cortex during stress?

Increases blood glucose and mobilizes energy stores. Glucocorticoid that promotes gluconeogenesis and protein breakdown.
Identify the neurotransmitter released by most sympathetic postganglionic neurons.

Norepinephrine. NE binds adrenergic receptors for sympathetic effects.
Which ANS division is characterized by "fight-or-flight" responses?

Sympathetic nervous system. Activates during stress to prepare body for action.
What are the two major divisions of the nervous system?

Central nervous system (CNS) and peripheral nervous system (PNS). CNS processes information centrally, while PNS relays sensory and motor signals peripherally.
What is the role of myelin in action potential conduction?

Increases conduction speed via saltatory conduction. Action potentials jump between nodes, speeding transmission.
What is an excitatory postsynaptic potential (EPSP)?

A graded depolarization that increases firing likelihood. Makes membrane potential closer to threshold.
What is the function of the hypothalamus in endocrine regulation?

Controls pituitary hormone release and maintains homeostasis. Links nervous and endocrine systems via pituitary control.
Which neurotransmitter is classically decreased in Parkinson disease?

Dopamine. Loss of dopaminergic neurons in substantia nigra causes symptoms.
What is the difference between an excitatory postsynaptic potential and an inhibitory postsynaptic potential?

EPSP depolarizes; IPSP hyperpolarizes the postsynaptic cell. EPSP makes firing more likely; IPSP makes it less likely.
Identify the endocrine gland that secretes insulin and glucagon to regulate blood glucose.

Pancreas (islets of Langerhans). Beta cells release insulin; alpha cells release glucagon.
Identify the negative feedback relationship between thyroid hormones and TSH.

High T $3$ /T $4$ decreases TSH; low T $3$ /T $4$ increases TSH. Classic endocrine feedback loop maintains thyroid homeostasis.
Which pituitary lobe stores and releases ADH and oxytocin?

Posterior pituitary. These hormones are made in hypothalamus, stored here.
What are nodes of Ranvier?

Gaps in myelin where action potentials regenerate. Unmyelinated segments allow ion exchange for signal propagation.
Which pituitary lobe releases ADH and oxytocin synthesized in the hypothalamus?

Posterior pituitary (neurohypophysis). Stores and releases hormones made by hypothalamic neurons.
What is saltatory conduction?

AP jumps node-to-node along myelinated axons. Myelin gaps (nodes) allow faster signal propagation.
Which ANS division mediates the "fight-or-flight" response?

Sympathetic nervous system. Activates during stress to increase heart rate, dilate pupils, and mobilize energy.
What is the neurotransmitter most associated with skeletal muscle contraction at the neuromuscular junction?

Acetylcholine (ACh). ACh binds nicotinic receptors causing muscle depolarization.
What is the neurotransmitter released by all preganglionic ANS neurons?

Acetylcholine. Both sympathetic and parasympathetic use ACh at ganglia.
Which hormone is produced by the pineal gland and helps regulate circadian rhythm?

Melatonin. Secreted at night to promote sleep-wake cycles.
Which adrenal region secretes cortisol as part of the long-term stress response?

Adrenal cortex. Outer layers produce steroid hormones for stress adaptation.
What is the resting membrane potential of a neuron primarily maintained by?

Na $^+$ /K $^+$ ATPase and selective K $^+$ leak channels. Pump maintains ion gradients; K $^+$ channels create negative potential.
Which glial cell myelinates axons in the peripheral nervous system (PNS)?

Schwann cells. Each Schwann cell myelinates one PNS axon segment.
Which synaptic receptors are ionotropic versus metabotropic?

Ionotropic: ligand-gated channels; Metabotropic: GPCRs. Ionotropic are fast ion channels; metabotropic use slow second messengers.
What is the all-or-none principle for action potentials?

If threshold is reached, an action potential fires at full amplitude. No partial action potentials exist - it's binary (fires or doesn't).
What event defines reaching threshold in a neuron?

Membrane depolarization sufficient to open voltage-gated Na $^+$ channels. Threshold represents the voltage where Na $^+$ channel activation triggers a self-regenerating depolarization.
What is an inhibitory postsynaptic potential (IPSP)?

A graded hyperpolarization that decreases firing likelihood. Makes membrane potential more negative than resting.
Which ion efflux primarily causes repolarization after an action potential peak?

Potassium ( $K^+$ ) efflux through voltage-gated channels. Opening of $K^+$ channels returns membrane to negative.
What pituitary hormone stimulates the adrenal cortex to release cortisol?

Adrenocorticotropic hormone (ACTH). Part of the HPA axis stress response cascade.
Which hormone increases blood glucose by promoting glycogen breakdown and gluconeogenesis?

Glucagon. Secreted by pancreatic alpha cells when glucose is low.
Which nervous system division is primarily responsible for fight-or-flight responses?

Sympathetic nervous system. Uses norepinephrine to increase heart rate, dilate pupils.
What ion movement primarily causes repolarization after the action potential peak?

K $^+$ efflux through voltage-gated K $^+$ channels. K $^+$ outflow restores negative membrane potential following Na $^+$ channel inactivation.
What is the defining electrical event of depolarization during an action potential?

Voltage-gated $Na^+$ channels open; $Na^+$ influx raises $V_m$ . Sodium rushes in when channels open, making inside less negative.
Which glial cells form myelin in the central nervous system?

Oligodendrocytes. Each wraps multiple CNS axons with myelin.
What event defines the depolarization phase of an action potential?

Voltage-gated $Na^+$ channels open; $Na^+$ influx. Positive charge rushes in, making the cell less negative.
Which ANS division mediates the "fight-or-flight" response?

Sympathetic nervous system. Activates during stress to prepare body for action.
What is the myelin sheath, and what is its main effect on conduction?

Glial insulation that increases action potential conduction speed. Myelin reduces membrane capacitance and increases resistance, allowing faster signal propagation via saltatory conduction.
What is the difference between absolute refractory period and relative refractory period?

Absolute: no AP possible; Relative: stronger stimulus required. Absolute has inactivated $Na^+$ channels; relative has recovering channels.
What is the primary role of the hypothalamus in endocrine regulation?

Controls pituitary hormone release and maintains homeostasis. Links nervous and endocrine systems via pituitary control.
Which endocrine gland is the primary controller of other endocrine glands, and what controls it?

Pituitary gland; controlled by the hypothalamus. Hypothalamus releases hormones that regulate pituitary secretions.
What is the all-or-none principle of action potentials?

Once threshold is reached, AP amplitude is constant; it does not scale. Stimulus strength affects frequency, not amplitude of APs.
What is the synaptic cleft?

The gap between presynaptic and postsynaptic neurons. 20-40 nm space where neurotransmitters diffuse across.
Which neurotransmitter is most associated with skeletal muscle contraction at the neuromuscular junction?

Acetylcholine (ACh). ACh binds nicotinic receptors causing muscle depolarization.
Which division of the autonomic nervous system mediates fight-or-flight responses?

Sympathetic nervous system. Releases norepinephrine to increase heart rate and alertness.
What neurotransmitter is most associated with skeletal muscle contraction at the neuromuscular junction?

Acetylcholine (ACh). ACh binds nicotinic receptors on muscle cells, triggering depolarization and contraction in the somatic nervous system.
What is the primary neurotransmitter classically associated with reward and motor pathways?

Dopamine. Dopamine modulates motivation and movement via pathways like the nigrostriatal and mesolimbic systems.
What is the all-or-none principle of an action potential?

If threshold is reached, AP fires at full amplitude; otherwise none. Binary response ensures consistent signal strength.
Which hypothalamic–pituitary–adrenal (HPA) axis hormone directly stimulates cortisol release?

ACTH (adrenocorticotropic hormone). Released by anterior pituitary to stimulate adrenal cortex.
What is the key distinction between the central and peripheral nervous systems?

CNS: brain and spinal cord; PNS: all nerves outside the CNS. CNS is protected by bone/meninges; PNS extends throughout body.
What is the primary function of a neuron's dendrites?

Receive synaptic input and conduct signals toward the soma. Dendrites are the input structures that transmit signals inward.
What is the primary role of the parasympathetic nervous system?

Rest-and-digest: conserves energy and promotes maintenance functions. Uses acetylcholine to slow heart rate and promote digestion.
What is the role of myelin in neuronal signaling?

It increases conduction velocity via electrical insulation. Myelin wraps axons, preventing ion leakage for faster signals.
What is the functional definition of a neuron in the nervous system?

An excitable cell that transmits information via electrical and chemical signals. Neurons use action potentials and neurotransmitters for communication.
What is the immediate effect of sympathetic activation on heart rate?

Increases heart rate. Prepares body for action by increasing cardiac output.
What is the defining electrical event of repolarization during an action potential?

Voltage-gated $K^+$ channels open; $K^+$ efflux lowers $V_m$ . Potassium exits when channels open, restoring negative charge.
Which hormone from the posterior pituitary primarily increases water reabsorption in the kidneys?

Antidiuretic hormone (ADH, vasopressin). ADH acts on collecting ducts to concentrate urine.
Which ion moves out of the neuron during the repolarization phase of an action potential?

$\text{K}^+$ efflux through voltage-gated channels. K+ channels open after Na+ channels, restoring negative charge.
What is the all-or-none principle of action potentials?

Once threshold is reached, AP amplitude is constant. No partial action potentials exist - it's binary.
Which ion moves into the neuron during the depolarization phase of an action potential?

$\text{Na}^+$ influx through voltage-gated channels. Voltage-gated Na+ channels open, causing rapid depolarization.
What is the primary function of efferent (motor) neurons in the nervous system?

Carry signals from the CNS to muscles and glands. Efferent means 'exiting' - these neurons send commands outward.
Which glial cell myelinates axons in the peripheral nervous system?

Schwann cell. Each Schwann cell myelinates only one PNS axon segment.
What is the refractory period's key functional consequence for neuronal firing?

Limits firing rate and enforces one-way propagation. Inactivated channels prevent immediate re-firing and backward propagation.
What is the name of the gap between myelinated segments on an axon?

Node of Ranvier. These gaps allow ion exchange for saltatory conduction.
What ion is most responsible for depolarization during the rising phase of an action potential?

Na $^+$ influx through voltage-gated Na $^+$ channels. Rapid channel opening causes membrane to become positive.
Which division of the autonomic nervous system mediates rest-and-digest responses?

Parasympathetic nervous system. Uses acetylcholine to slow heart rate and promote digestion.
Which ANS division mediates the "rest-and-digest" response?

Parasympathetic nervous system. Promotes energy conservation and digestion when the body is relaxed.
What is the function of the hypothalamus in endocrine regulation?

Controls pituitary hormone release and homeostasis. Links nervous and endocrine systems via releasing hormones.
What is an excitatory postsynaptic potential (EPSP)?

Postsynaptic depolarization that increases firing likelihood. Makes membrane potential less negative, closer to threshold.
Which pituitary lobe releases ADH and oxytocin into the bloodstream?

Posterior pituitary. Stores and releases hypothalamic hormones, not produces them.
What is the functional difference between excitatory and inhibitory postsynaptic potentials?

EPSPs depolarize; IPSPs hyperpolarize the postsynaptic membrane. EPSPs increase firing likelihood; IPSPs decrease it.
What is the role of the sodium-potassium pump in neurons?

Maintains ion gradients by pumping $3Na^+$ out and $2K^+$ in. Uses ATP to maintain resting potential against concentration gradients.
What neurotransmitter is most associated with skeletal muscle contraction at the neuromuscular junction?

Acetylcholine. Binds nicotinic receptors on muscle cells.
What is the all-or-none principle for action potentials?

Once threshold is reached, action potential amplitude is fixed. Stimulus strength affects frequency, not amplitude of firing.
What is an inhibitory postsynaptic potential (IPSP)?

Postsynaptic hyperpolarization that decreases firing likelihood. Makes membrane potential more negative, away from threshold.
Identify the structure where action potentials "jump" between myelinated segments.

Nodes of Ranvier. Gaps in myelin where voltage-gated channels cluster.
What is the hypothalamic–pituitary axis (HPAx) in endocrine regulation?

Hypothalamus controls pituitary, which controls peripheral endocrine glands. The axis integrates neural and hormonal signals, with hypothalamic hormones regulating pituitary release to influence distant glands.
Which autonomic division is primarily responsible for 'rest-and-digest' functions?

Parasympathetic nervous system. Active during relaxation: slows heart, promotes digestion.
What hormone increases water reabsorption in the kidney collecting ducts?

Antidiuretic hormone (ADH, vasopressin). ADH conserves body water by reducing urine production.
Which adrenal hormones primarily mediate the acute fight-or-flight response?

Epinephrine and norepinephrine (adrenal medulla catecholamines). Released by sympathetic stimulation for immediate stress response.
What is saltatory conduction?

Action potentials jump node-to-node at nodes of Ranvier. Myelin gaps allow rapid, energy-efficient conduction.
What is the function of myelin on an axon?

Increase conduction speed via insulation. Myelin wraps axons, allowing saltatory conduction between nodes.
What is the key functional distinction between the somatic and autonomic nervous systems?

Somatic controls skeletal muscle; autonomic controls viscera. Voluntary vs involuntary control of effector organs.
Which pancreatic hormone lowers blood glucose by increasing cellular uptake and glycogen synthesis?

Insulin. Promotes glucose storage in liver and muscle cells.
Which hormone is released from the posterior pituitary to increase water reabsorption in kidneys?

Antidiuretic hormone (ADH, vasopressin). ADH acts on collecting ducts to conserve body water.
Which glial cells form myelin in the peripheral nervous system?

Schwann cells. Each wraps one PNS axon segment with myelin.
What hormone is released by the adrenal medulla to support acute sympathetic responses?

Epinephrine (and norepinephrine). Catecholamines amplify fight-or-flight response within seconds.
What is the role of the myelin sheath in neural signaling?

Increases conduction velocity by insulating the axon. Prevents ion leakage and speeds signal propagation.
What event defines the repolarization phase of an action potential?

Voltage-gated $K^+$ channels open; $K^+$ efflux. Positive charge exits, restoring negative resting potential.
Which hypothalamic–pituitary–adrenal (HPA) axis hormone is the main glucocorticoid in humans?

Cortisol. Released from adrenal cortex; regulates metabolism and immune response.
What is the primary function of a neuron's axon?

Conduct action potentials away from the soma to terminals. Axons are output structures carrying signals to other neurons.
What is saltatory conduction?

Action potentials "jump" between nodes of Ranvier on myelinated axons. Myelin gaps allow rapid signal propagation via jumping.
What are the nodes of Ranvier?

Gaps in myelin where voltage-gated channels regenerate the signal. These unmyelinated segments concentrate ion channels, allowing action potential regeneration during saltatory conduction.
What is the primary function of the axon in a neuron?

Conduct action potentials away from the soma. Axons propagate electrical impulses to synaptic terminals, enabling long-distance communication within the nervous system.
What is the resting membrane potential mainly determined by in neurons?

K $^+$ leak channels and the Na $^+$ /K $^+$ ATPase. High permeability to K $^+$ establishes a negative potential, maintained by the pump's active transport against gradients.
What is the definition of an action potential in a neuron?

Rapid, all-or-none membrane depolarization. Voltage-gated channels open at threshold, causing complete depolarization.
What is the primary function of the somatic nervous system?

Voluntary control of skeletal muscles and somatic sensation. Controls conscious movements and processes sensory information from skin, muscles, and joints.
What is the neurotransmitter released by all autonomic preganglionic neurons?

Acetylcholine. Both sympathetic and parasympathetic use ACh at ganglia.
What is the functional difference between the somatic nervous system and autonomic nervous system?

Somatic: voluntary skeletal muscle; Autonomic: involuntary viscera. Somatic controls conscious movement; autonomic regulates unconscious functions.
What is the primary function of a neuron's dendrites?

Receive incoming signals from other neurons. Dendrites branch out to collect chemical signals from neighboring neurons.
What type of glial cell myelinates axons in the peripheral nervous system?

Schwann cell. Each Schwann cell myelinates one PNS axon segment.
What is the resting membrane potential of a typical neuron?

Approximately $-70\ \text{mV}$ . Maintained by $\text{Na}^+$ / $\text{K}^+$ pump and ion permeability.
What is the primary function of a neuron's dendrites?

Receive incoming signals from other neurons. Dendrites branch extensively to maximize signal reception surface area.
Which adrenal region secretes epinephrine and norepinephrine?

Adrenal medulla. Part of sympathetic response, releases catecholamines.
What neurotransmitter is released by all autonomic preganglionic neurons?

Acetylcholine. Both sympathetic and parasympathetic use ACh at ganglia.
Which neurotransmitter is the primary inhibitory transmitter in the adult brain?

GABA. Opens Cl $^-$ channels causing hyperpolarization.
What is the difference between an EPSP and an IPSP?

EPSP depolarizes; IPSP hyperpolarizes the postsynaptic membrane. EPSP makes firing more likely; IPSP makes firing less likely.
What is the key functional role of myelin on an axon?

Increases conduction velocity by insulating the axon. Prevents ion leakage, forcing AP to jump between nodes rapidly.
What ion efflux primarily causes repolarization after an action potential peak?

K $^+$ efflux through voltage-gated K $^+$ channels. K $^+$ exits cell, restoring negative membrane potential after depolarization.
What is the primary role of the Na $^+$ /K $^+$ ATPase in neurons?

Maintains Na $^+$ and K $^+$ gradients using ATP. Pumps 3 Na $^+$ out and 2 K $^+$ in to maintain resting potential.
What is the correct order of structures that an action potential passes on a typical neuron?

Dendrites → soma → axon hillock → axon → axon terminals. Signal flows from input to integration to initiation to conduction to output.
Which neurotransmitter is classically associated with reward and motivation pathways?

Dopamine. Released in ventral tegmental area projecting to nucleus accumbens.
What is saltatory conduction?

APs jump node-to-node along myelinated axons (nodes of Ranvier). Myelin insulation speeds conduction by 100x.
What is the typical resting membrane potential of a neuron?

Approximately $-70\ \text{mV}$ . Maintained by Na+/K+ pump with more K+ inside, Na+ outside.
What two hormones are released from the posterior pituitary gland?

ADH (vasopressin) and oxytocin. Made in hypothalamus but stored/released from posterior pituitary.
Which autonomic division is primarily responsible for "rest-and-digest" responses?

Parasympathetic nervous system. Conserves energy: slows heart rate, stimulates digestion, constricts pupils.
Which adrenal hormone is the main long-term stress hormone that increases blood glucose?

Cortisol (from adrenal cortex). Glucocorticoid that mobilizes glucose during chronic stress.
What is the primary effect of an excitatory postsynaptic potential (EPSP)?

Depolarizes postsynaptic membrane, increasing likelihood of firing. Makes membrane potential less negative, closer to threshold.
What is the definition of an inhibitory postsynaptic potential (IPSP)?

Postsynaptic hyperpolarization decreasing firing likelihood. Makes membrane potential more negative, farther from threshold.
What is the difference between an excitatory postsynaptic potential and inhibitory postsynaptic potential?

EPSP depolarizes; IPSP hyperpolarizes (often via $Cl^-$ or $K^+$ ). EPSPs increase firing likelihood; IPSPs decrease it via ion movements.
What is the synaptic cleft?

The gap between presynaptic terminal and postsynaptic membrane. ~20nm space where neurotransmitters diffuse to reach receptors.
Which division of the nervous system includes the sympathetic and parasympathetic branches?

Autonomic nervous system. Regulates involuntary functions like heart rate and digestion.
What is the functional role of dendrites in a neuron?

Receive synaptic input and conduct it toward the soma. Tree-like extensions increase surface area for receiving signals.
What is the primary function of the central nervous system (CNS)?

Integrates information and coordinates responses. The brain and spinal cord process sensory input and generate motor output.
Identify the key difference between absolute and relative refractory periods.

Absolute: no AP possible; Relative: stronger stimulus required. Absolute refractory period results from Na $^+$ inactivation; relative from lingering K $^+$ conductance.
Which ion efflux primarily causes repolarization after the action potential peak?

K $^+$ efflux through voltage-gated K $^+$ channels. Restores negative membrane potential after depolarization.
What is the correct direction of information flow in a typical reflex arc?

Sensory neuron → interneuron (spinal cord) → motor neuron. Bypasses brain for rapid response to stimuli.
Identify the neurotransmitter most associated with neuromuscular junction signaling.

Acetylcholine (ACh). ACh binds nicotinic receptors to trigger muscle contraction.
Which ANS branch is associated with "fight-or-flight" physiology?

Sympathetic nervous system. Activates during stress for rapid energy mobilization.
Which endocrine gland secretes epinephrine and norepinephrine in acute stress?

Adrenal medulla. Modified sympathetic neurons release catecholamines directly.
What ion movement primarily causes repolarization of the neuron after an action potential peak?

K $^+$ efflux through voltage-gated K $^+$ channels. K $^+$ leaves cell, restoring negative membrane potential.
What is the primary function of afferent (sensory) neurons in the nervous system?

Carry signals from sensory receptors to the CNS. Afferent means 'arriving' - these neurons bring sensory info inward.
What neurotransmitter is most associated with skeletal muscle contraction at the NMJ?

Acetylcholine (ACh). ACh binds nicotinic receptors at neuromuscular junction for contraction.
What type of glial cell myelinates axons in the central nervous system?

Oligodendrocyte. Each oligodendrocyte can myelinate multiple CNS axons.
Which ion influx is primarily responsible for the depolarization phase of an action potential?

Sodium ( $Na^+$ ) influx through voltage-gated sodium channels. Opening of $Na^+$ channels causes rapid membrane depolarization.
Which adrenal region secretes epinephrine and norepinephrine?

Adrenal medulla. Inner adrenal region acts like sympathetic neurons.
What is the primary role of the sympathetic nervous system?

Fight-or-flight: mobilizes energy and increases arousal. Releases norepinephrine/epinephrine for stress response.
Identify whether an inhibitory postsynaptic potential (IPSP) increases or decreases firing likelihood.

Decreases likelihood of action potential firing. Hyperpolarizes the membrane away from threshold.
Which neurotransmitter is most strongly associated with mood regulation and depression?

Serotonin. SSRIs treat depression by increasing synaptic serotonin.
What is the function of myelin, and which cells form it in the CNS versus PNS?

Speeds conduction; CNS: oligodendrocytes, PNS: Schwann cells. Insulates axons for saltatory conduction via different glial cells.
What is the all-or-none principle of action potentials?

If threshold is reached, firing occurs at full amplitude. No partial action potentials exist - it's binary.
Which ANS division is classically described as "rest-and-digest"?

Parasympathetic nervous system. Promotes energy conservation and digestion when relaxed.
Which autonomic division is primarily responsible for 'fight-or-flight' responses?

Sympathetic nervous system. Activates during stress: increases heart rate, dilates pupils.
What brain structure is most directly responsible for homeostasis and regulating the pituitary gland?

Hypothalamus. Links nervous and endocrine systems, controls body balance.
What is the primary function of a neuron's axon?

Transmit action potentials away from the soma. The axon is the neuron's output cable, carrying signals to other cells.
Which brain structure is the major relay station for sensory information to the cortex?

Thalamus. All senses except smell pass through thalamus first.
Which ANS division is classically described as "fight-or-flight"?

Sympathetic nervous system. Activates during stress for rapid energy mobilization.
Which glial cell myelinates axons in the central nervous system?

Oligodendrocyte. Each oligodendrocyte can myelinate multiple CNS axons.
Identify the main endocrine pathway: hypothalamus → pituitary → target gland is called what axis?

Hypothalamic-pituitary axis. Central control system linking nervous and endocrine systems.
What is the key functional difference between ionotropic and metabotropic receptors?

Ionotropic: ligand-gated channels; Metabotropic: GPCR second messengers. Ionotropic receptors directly alter ion flow for fast responses, while metabotropic activate intracellular cascades for slower, modulatory effects.
What are the two major divisions of the peripheral nervous system (PNS)?

Somatic nervous system and autonomic nervous system. PNS divides into motor (somatic) and regulatory (autonomic) branches.
What is the role of myelin in action potential conduction?

Increases conduction speed via saltatory conduction. Insulation allows action potentials to jump between nodes of Ranvier.
What are the glial cells that myelinate axons in the peripheral nervous system?

Schwann cells. Wrap around single axons in nerves outside CNS.
What is saltatory conduction, and where does it occur?

AP "jumps" node-to-node on myelinated axons at nodes of Ranvier. Myelin gaps expose membrane only at nodes for faster signal propagation.
What is an excitatory postsynaptic potential (EPSP)?

Graded depolarization that increases likelihood of firing an action potential. EPSPs summate at the axon hillock, bringing membrane potential closer to threshold for action potential initiation.
Which brain structure regulates homeostasis and controls the pituitary gland?

Hypothalamus. Links nervous and endocrine systems via pituitary control.
Which ion's influx primarily causes the depolarization phase of an action potential?

Na $^+$ influx. Voltage-gated Na $^+$ channels open, making membrane potential positive.
What is an inhibitory postsynaptic potential (IPSP)?

Graded hyperpolarization that decreases likelihood of firing. IPSPs move membrane potential away from threshold, reducing neuronal excitability through hyperpolarization.
Which adrenal region secretes epinephrine and norepinephrine during acute stress?

Adrenal medulla. Modified sympathetic neurons release catecholamines directly.
What is the all-or-none principle of an action potential?

If threshold is reached, a full action potential occurs; no partial firing. Action potentials have fixed amplitude once triggered.
What is the key functional difference between the somatic and autonomic nervous systems?

Somatic is voluntary; autonomic regulates involuntary functions. Somatic controls skeletal muscle; autonomic controls organs.
What is the main effect of sympathetic activation on heart rate and bronchioles?

Increases heart rate and dilates bronchioles. Prepares body for increased oxygen demand during stress.
What is the correct order of information flow in a basic reflex arc?

Receptor → sensory neuron → interneuron → motor neuron → effector. Shows the complete pathway from stimulus to response.
What is the key distinction between the somatic and autonomic nervous systems?

Somatic: voluntary skeletal muscle; Autonomic: involuntary viscera. Somatic system controls conscious movements, whereas autonomic regulates automatic functions like heart rate.
Which endocrine gland releases epinephrine and norepinephrine during acute stress?

Adrenal medulla. Part of sympathetic response; releases catecholamines into bloodstream.
What is the effect of myelination on action potential conduction velocity?

Increases conduction velocity by reducing current leak. Myelin acts as insulation, preventing ion flow across membrane.
Which brain structure is the primary regulator of homeostasis and endocrine control via the pituitary?

Hypothalamus. Links nervous and endocrine systems to maintain internal balance.
What is the functional difference between an EPSP and an IPSP?

EPSP depolarizes; IPSP hyperpolarizes the postsynaptic cell. EPSPs increase firing likelihood; IPSPs decrease it.
What is the role of myelin in neural signaling?

Increases conduction velocity via saltatory conduction. Action potentials jump between nodes, speeding transmission.
What is the main effect of parasympathetic activation on heart rate and digestion?

Decreases heart rate and increases digestive activity. Promotes energy conservation and nutrient absorption.
What ion influx causes the rapid depolarization phase of an action potential?

Na $^+$ influx through voltage-gated Na $^+$ channels. Positive Na $^+$ ions rush in when channels open, making cell less negative.
What is the difference between a sensory (afferent) neuron and a motor (efferent) neuron?

Afferent: to CNS; Efferent: from CNS to muscles/glands. Afferent carries sensory input; efferent carries motor output.
What hormone from the anterior pituitary stimulates the thyroid gland?

Thyroid-stimulating hormone (TSH). Part of the hypothalamic-pituitary-thyroid axis regulating metabolism.
Identify the ion movement that primarily causes repolarization after the action potential peak.

Voltage-gated $\text{K}^+$ efflux. Opening of channels restores negative membrane potential.
Identify whether an excitatory postsynaptic potential (EPSP) increases or decreases firing likelihood.

Increases likelihood of action potential firing. Depolarizes the postsynaptic membrane toward threshold.
What is the absolute refractory period?

Time when no new action potential can be initiated. $\text{Na}^+$ channels are inactivated, preventing new APs.
What neurotransmitter is classically associated with reward and motivation pathways?

Dopamine. Key neurotransmitter in mesolimbic pathway for reward processing.
Which glial cell type myelinates axons in the peripheral nervous system?

Schwann cells. Each cell wraps around a single axon segment in peripheral nerves.
What is the absolute refractory period?

Time when no new AP can occur because $Na^+$ channels are inactivated. Ensures unidirectional propagation of action potentials.
Which autonomic division is characterized by "fight-or-flight" physiology?

Sympathetic nervous system. Mobilizes energy and increases heart rate for emergencies.
Which ion influx primarily causes the depolarization phase of an action potential?

Na $^+$ influx through voltage-gated Na $^+$ channels. Opening of channels causes rapid membrane depolarization.
What is the functional role of the axon in a neuron?

Conduct action potentials away from the soma to terminals. Long projection carries electrical signals to synaptic terminals.
What is the functional difference between the central nervous system and peripheral nervous system?

CNS: brain/spinal cord; PNS: nerves connecting CNS to body. CNS processes information; PNS relays signals between CNS and periphery.
Identify the main function of myelin in the nervous system.

Increases action potential conduction speed via insulation. Myelin acts as electrical insulation, enabling faster signal transmission.
Identify the neuron structure that propagates the action potential away from the soma.

Axon. Long projection that transmits electrical signals to other neurons.
Which hormone from the adrenal medulla mediates rapid sympathetic responses to stress?

Epinephrine (and norepinephrine). Acts like injectable adrenaline during acute stress.
What is the immediate ionic cause of the repolarization phase of an action potential?

Voltage-gated $K^+$ channels open; $K^+$ efflux. Potassium exits to restore negative resting potential.
Which pituitary lobe releases oxytocin and antidiuretic hormone (ADH) into the blood?

Posterior pituitary. Stores and releases hormones made by hypothalamic neurons.
Which pituitary lobe stores and releases ADH and oxytocin?

Posterior pituitary. These hormones are made in hypothalamus, stored in posterior pituitary.
Which pituitary lobe releases hormones synthesized in the hypothalamus (ADH and oxytocin)?

Posterior pituitary. Stores and releases neurohormones made by hypothalamic neurons.
What is the primary function of dendrites in a neuron?

Receive synaptic input and carry it toward the soma. Dendrites integrate incoming signals from other neurons, facilitating information flow to the cell body for processing.
Which autonomic branch is classically described as "fight-or-flight"?

Sympathetic nervous system. Increases heart rate, dilates pupils, and mobilizes energy.
Which process terminates neurotransmitter signaling by moving it back into the presynaptic neuron?

Reuptake. Transporters recycle neurotransmitters, efficiently clearing the synaptic cleft to terminate signaling.
What is the all-or-none principle for action potentials?

Once threshold is reached, AP amplitude is constant. Ensures reliable signal transmission regardless of stimulus strength.

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