There are five layers of the epidermis. From surface to base, the layers are the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum and stratum basalis.

The stratum corneum is composed of several layers of barrier cells and serves mostly for protection. The stratum lucidum is only found in the palms and soles and helps thicken the skin. The stratum granulosum contains lipids and fatty acids. The stratum spinosum contains some immune cells, as well as lipids. The stratum basalis contains melanocytes and mechanoreceptor cells attached to the basement membrane.

There are five layers of the epidermis. From surface to base, the layers are the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum and stratum basalis.

The stratum corneum is composed of several layers of barrier cells and serves mostly for protection. The stratum lucidum is only found in the palms and soles and helps thicken the skin. The stratum granulosum contains lipids and fatty acids. The stratum spinosum contains some immune cells, as well as lipids. The stratum basalis contains melanocytes and mechanoreceptor cells attached to the basement membrane.

Endocrine organs are capable of secreting hormone signals into the blood. The heart releases atrial-natriuretic hormone, which stimulates vasodilation to reduce blood pressure and affects kidney function. The liver releases insulin-like growth factor in response to growth hormone, which has direct effects on stimulating cell growth and division. The kidneys release renin, which acts to increase blood pressure via sodium retention. The pancreas secretes insulin and glucagon to regulate blood glucose concentration.

The medulla oblongata is located in the brain stem and regulates several vital functions, such as respiration and heart rate. It performs these actions via action potentials and innervation, rather than the secretion of hormones.

The correct answer is 5 roots. They are roots C5-C8 and T1.

The correct answer is 5 roots. They are roots C5-C8 and T1.

Endocrine organs are capable of secreting hormone signals into the blood. The heart releases atrial-natriuretic hormone, which stimulates vasodilation to reduce blood pressure and affects kidney function. The liver releases insulin-like growth factor in response to growth hormone, which has direct effects on stimulating cell growth and division. The kidneys release renin, which acts to increase blood pressure via sodium retention. The pancreas secretes insulin and glucagon to regulate blood glucose concentration.

The medulla oblongata is located in the brain stem and regulates several vital functions, such as respiration and heart rate. It performs these actions via action potentials and innervation, rather than the secretion of hormones.

The precentral gyrus is an important fold found in the frontal lobe and is a landmark for the primary motor area. The parietal lobe contains another important gyrus called the postcentral gyrus, which is the landmark for the somatosensory area of the cerebral cortex. The primary auditory area is located in the temporal lobe while the primary visual area is located in the occipital lobe. The insula is a structure that lies within the lateral fissure. It cannot be seen in the external view of the brain and plays a role in the limbic system.

The phrenic nerve is the innervation for the diaphragm. It originates in the cervical spine at the levels of C3-C5. There are two phrenic nerves (left and right), which innervate their respective sides of the diaphragm. A helpful phrase to remember this is "C3,C4,C5 keeps the diaphragm alive!"

The corpus callosum is a wide bundle of neural fibers that connects the left and right cerebral hemispheres, allowing for interhemispheric communication. It consists of approximately 200-250 million axonal projections, making it the largest white matter structure in the brain (it has a high myelin content, thus facilitating faster information transmission).

The fornix is part of the limbic system; it allows for communication from the hippocampus to the mammillary bodies and then onto the thalamus. The thalamus is a relay station for sensory and motor signals to the cerebral cortex. The tectum is the dorsal portion of the midbrain.

The meninges consist of three layers of connective tissue that surround the central nervous system. Dura mater is the thick outermost layer and serves to partition the central nervous system and meninges from the rest of the body. Arachnoid mater is the loose middle layer with a web-like appearance and helps cushion and protect the central nervous system. The subarachnoid space exists between the arachnoid and pia mater and is filled with cerebrospinal fluid. Pia mater is the delicate inner layer that adheres to the surface of the brain and spinal cord, creating one final barrier.