Nervous System and Neurons

Adrenaline (epinephrine) directly stimulates the sinoatrial (SA) node, increasing heart rate and cardiac output. It binds to beta-1 adrenergic receptors on SA node cells, enhancing the rate of depolarization and firing frequency.

Neurofilaments are the intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and are believed to function primarily to provide structural support for the axon and to regulate axon diameter. Neurofilaments are composed of polypeptide chains or subunits which belong to the same protein family.

Innervation of the penis comes from the pudendal nerve which is made up of the 2nd, 3rd and 4th sacral nerves. The penile nerve (also known as the dorsal nerve of the penis) is the deepest branch of the pudendal nerve.

The brainstem includes the midbrain, pons and medulla. It acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. Ten of the twelve cranial nerves originate in the brainstem.

During rest, the vagal tone is the dominant. There is continuous parasympathetic activity that has a negative chronotropic character.

Somatic nervous system is a subdivision of the PNS that controls voluntary activities such as the activation of skeletal muscles.

A complex material formed of protein and phospholipid (fat) that is laid down as a sheath around the axons of certain neurons. It iIncreases the rate of transmission of nerve impulses.

This nerve innervates the muscles of the tongue.

Sympathetic nervous system stimulation causes vasoconstriction of most blood vessels, including those of the skeletal muscle.

In a neuron, the dendrite receives a signal from an axon terminal of a neuron through a synapse.

The axolemma is the cell membrane surrounding an axon. It is responsible for maintaining the membrane potential of the neuron, and it contains ion channels through which ions can flow.

A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. There are 31 pairs of spinal nerves, one on each side of the human vertebral column.

A pseudounipolar neuron is a kind of sensory neuron in the peripheral nervous system. This neuron contains an axon that has split into two branches; one branch runs to the periphery and the other to the spinal cord.

The abducens innervates the lateral rectus muscles of the eye.

Dendrites are the short, branched fibers of neurons that receive nerve impulses from other neurons or sensory receptors and conduct them toward the cell body. They increase the surface area for receiving signals from other neurons.