White fibers have less myoglobin than red fibers. White fibers have less mitochondria than red fibers. White fibers fatigue more quickly than red fibers. 

White fibers primarily use anaerobic respiration (red primarily uses aerobic). Remember that red fibers are active over long periods of sustained stress, while white fibers are more explosive. Red fibers require oxygen from respiration and myoglobin to maintain activity.

When acetylcholine binds to its receptors at the neuromuscular junction, it stimulates an initial influx of sodium ions that cause a localized depolarization of the muscle cell. This depolarization causes voltage-gated calcium channels to open within the T-tubules, carrying the signal into the cell interior. Proteins in the wall of the T-tubules directly interact with the internal sarcoplasmic reticulum, stimulating the organelle to release intracellular calcium. This release liberates myosin-binding sites on actin, allowing contraction to occur.

Sodium ions, potassium ions, and chloride ions play important roles in maintaining membrane potential at the neuromuscular junction, but the T-tubules rely heavily on calcium to interact with the sarcoplasmic reticulum.

Since the triceps and biceps produce opposing motions in the arm, they can be considered antagonists of one another. An antagonist will stretch, while the agonist contracts, and vice versa. Extensors, such as the triceps brachii, will act as antagonists of flexors, such as the biceps brachii.

A synergist assists the agonist by stabilizing the origin bone.

The medulla oblongata is responsible for autonomic functions, such as breathing rate and heart rate regulation. Dysfunction of the medulla oblongata could result in problems with breathing rhythm.

The cerebellum is responsible for coordination and balance. The hypothalamus regulates the fight-or-flight response, sex drive, thirst, and hunger. The midbrain is the center for auditory and visual signal relay to the cortex. The hippocampus functions in the retention of memories.

The neuron has three major portions: the dendrites, the cell body, and the axon. The dendrites receive electrical stimulation from other neurons, and the axon sends electrical signals to other neurons.

Signals travel down the axon until they reach the axon terminal. Vesicles of neurotransmitter are released from the axon terminal, where they travel across the synapse to the dendrite of the post-synaptic neuron. This initiates a signal in the dendrite, which is carried to the cell body. Signals from different dendrites sum together in the axon hillock, which can stimulate depolarization of the axon and allow for signal propagation.

Accommodation of the lens for near vision is a parasympathetic controlled response. Each of the other answer choices is a sympathetic controlled response. The parasympathetic nervous system pertains to "rest and digest" activities. The sympathetic nervous system pertains to "fight or flight" activities. In the case of the eye lens, the ciliary muscle is innervated by parasympathetic fibers, which, when activated, cause the muscle to contract and change the shape of the lens. This alters the refractive capability in a way to accommodate near vision.

Spinal nerves coming off of the spinal cord can be thought of as the combination of both posterior and anterior roots. This means that they contain both sensory and motor neuron axons. These nerves can also carry autonomic functions to organs of the body as well.

Relaxation of bronchial smooth muscle is an involuntary process, which is accomplished by the autonomic system rather than the somatic. It is also a part of the "fight or flight" response, which relates to the sympathetic system. Postganglionic neurons directly stimulate target tissues, while preganglionic neurons stimulate postganglionic neurons.

The nervous system has a variety of support cells in addition to neurons. These support cells are collectively called the neuroglia.

Microglia are used to remove debris from the nervous system, astrocytes provide support to neurons, and Schwann cells are used to myelinate the axons in the peripheral nervous system. It is the role of ependymal cells to synthesize and circulate cerebrospinal fluid using their cilia.

The cerebellum is found in the posterior portion of the brain and controls balance and coordination. The cerebrum controls upper level cognition, such as conscious thought, and memory. The hypothalamus is a crucial endocrine structure and helps regulate hormone secretion from the pituitary and body homeostasis. The brain stem controls the most basic duties of the body, which include breathing rate, heart rate, and blood pressure.