Endocrine vs Neural Control - Anatomy and Physiology
- How does each system carry its signal to target cells: neural control versus endocrine control?
- Neural: electrical impulses along axons, then neurotransmitter across a synapse. Endocrine: hormones carried by the blood.
- Over what distance does a neurotransmitter act, compared with a hormone?
- A neurotransmitter crosses only a narrow synaptic cleft (tens of nanometers); a hormone travels through the bloodstream to targets anywhere in the body.
- Norepinephrine is released by a sympathetic nerve ending onto a target and also by the adrenal medulla into blood. How is it classified in each case?
- As a neurotransmitter at the nerve ending and as a hormone when released into blood. The classification depends on delivery route, not the molecule.
- What determines which cells respond to a neural signal?
- Anatomical connection: only the cells that a neuron synapses with receive its neurotransmitter.
- How does the nervous system encode signal strength, compared with the endocrine system?
- The nervous system uses the frequency of action potentials; the endocrine system uses the concentration of hormone in the blood.
- What are neurons that release hormones into the blood called, and what is a classic example?
- Neurosecretory (neuroendocrine) cells, such as hypothalamic neurons that release ADH and oxytocin from the posterior pituitary.
- What determines which cells respond to a circulating hormone?
- Whether the cells have specific receptors for that hormone. Every cell is exposed, but only cells with the receptor respond.
- Which endocrine gland is a modified sympathetic ganglion that releases epinephrine into the blood?
- The adrenal medulla.
- Which control system, neural or endocrine, typically produces longer-lasting effects?
- Endocrine control. Hormone effects can persist for minutes to days, while neural effects usually stop soon after stimulation ends.
- Which control system, neural or endocrine, has the faster onset of response?
- Neural control, which responds within milliseconds; endocrine responses take seconds to hours or longer.
- Which control system, neural or endocrine, mainly regulates long-term processes such as growth, puberty, and metabolic rate?
- The endocrine system, because these processes require sustained signals acting on many tissues.