When the nucleus propulsus inside an intervertebral disk protrudes through a weakened area of the annulus fibrosus, the ability of that disk to respond to torsion forces is severely compromised. Further, the protruding nucleus itself puts pressure on the vertebrae, resulting in a "compressed" or herniated disk. This can impact nearby nerves, resulting in radiating pain, weakness, and numbness or tingling.

The autonomic nervous system (ANS) consists of a set of pathways to and from the central nervous system (CNS) that innervate and regulate smooth muscle, cardiac muscle, and glands. The ANS is distinct from the somatic nervous system, which innervates skeletal muscle. The ANS has three divisions the sympathetic, parasympathetic, and enteric nervous systems.

Golfer's elbow, or medial epicondylitis, is due to inflammation of the medial epicondyle of the elbow. The tendons of several muscles involved in flexing the forearm, wrist, and fingers originate at the medial epicondyle of the humerus at the elbow and this insertion point can become inflamed in response to injury.

Lateral epicondylitis is sometimes associated with tennis elbow.

Veins always carry blood towards the heart. The blood in veins is mostly deoxygenated, however the pulmonary vein, which goes from the lungs to the left atrium, carries newly oxygenated blood back to the heart for it to be pumped to the rest of the body.

In contrast, arteries always travel away from the heart and usually carry oxygenated blood, with the exception of the pulmonary arteries. Arteries and arterioles have a thick layer of smooth muscle that helps to regulate blood pressure. Veins may have some smooth muscle, but are not nearly as significant in helping to regulate blood flow.

The correct answer is red marrow.

Hematopoiesis is the formation of blood cells, which is a function of red marrow. Red marrow forms red blood cells, white blood cells and blood platelets. The process beings with a stem cell that proliferates (reproduces rapidly), differentiates (becomes a specialized cell) and replicates (duplicates).

The other choices are all parts of bones, but have different functions/characteristics besides hematopoiesis. While red marrow contains the red and white blood cells and blood platelets, yellow marrow consists of mostly fat cells. Compact bones are hard and contain closely packed osteons that form a solid mass. The periosteum is the connective tissue covering the surface of a bone. Spongy bones are less dense than compact bone and are lighter than compact bones. It contains plates (trabeculae) of bone and cavities that contain the red marrow.

The axis is the only bone listed that is not a long bone. The axis is the second cervical vertebra (C2) and is classified as an irregular bone.

The mouth is the start of the gastrointestinal tract. It is the site of both mechanical and chemical digestion via chewing, and saliva, respectively. Saliva contains the enzyme amylase that breaks down carbohydrates.

GABA is the only neurotransmitter to actively suppress the formation of an action potential when binding to the dendrites on the postsynaptic neuron.

Norepinephrine, dopamine, serotonin, and glutamate have various physiological effects in different regions of the body, but all acts to stimulate the formation of an action potential.

The mouth, stomach, and small intestine all contain enzymes that help chemically digest food. The mouth contains salivary amylase to digest carbohydrates. The stomach contains pepsin to digest proteins. The small intestine contains numerous enzymes from pancreatic secretions that digest carbohydrates, fats, and proteins.

The esophagus serves to transport food from the mouth to the stomach via smooth muscle contractions. No chemical digestion takes place in the esophagus, and no digestive enzymes are secreted into this region.

The endosteum is the layer that is found deep to all layers. It is found in the inner lining of the bone. Meanwhile, the periosteum is the most superficial layer of the bone which compromises the outer covering of bones.