Module 1 APII

What neurotransmitter is found at the neuromuscular junctions?

Acetylcholine

What are the peripheral nervous system neuroglial cell types?

Schwann cells; satellite cells

What are the 2 divisions of the efferent division of the peripheral nervous system?

Somatic system and the autonomic system.

Why is a spinal reflex faster than a conscious decision to move by the brain?

Spinal reflexes are faster not only because they involve fewer neurons, but also because the electrical signal does not have to travel to the brain and back. Spinal reflexes only travel to the spinal cord and back which is a much shorter distance.

What is the purpose of the stretch reflex?

Stretch reflexes are a special type of muscle reflex which protect the muscle against increases in length which may tear or damage muscle fibers.

What are the 2 divisions of the autonomic nervous system?

Sympathetic and parasympathetic nervous system

____ neurons have one extension off the cell body which branches into two: one central process running to the CNS and another peripheral process running to the sensory receptor.

Unipolar (pseudounipolar)

Motor neurons (axons) leave the spinal cord via the ____.

Ventral root

Collections of cell bodies inside the peripheral nervous system are called _____, and the collection of nerve axons in the peripheral nervous system are called _____.

ganglia, nerves.

Describe the movement of nerve impulses in the peripheral nervous system.

he peripheral nervous system receives impulses from the sensory organs via the afferent division and then relays signals or impulses from the central nervous system to muscles and glands via the motor or efferent division.

Collections of cell bodies inside the central nervous system are called _____, and the collection of nerve axons in the central nervous system are called _____.

nuclei, tracts.

When does a ventral root transition to a spinal nerve?

A spinal nerve contains both sensory and motor neurons from the ventral and dorsal roots.

Once ACh is released in the NMJ, what happens to cause muscle contraction to occur?

Acetylcholine binds to receptors on the muscle fiber that cause sodium channels to open. Sodium rushes out of the muscle cell, triggering an action potential which reaches the sarcoplasmic reticulum. Calcium ions are released from the sarcoplasmic reticulum of the muscle cell causing the muscle to contract.

What are the 2 divisions of the peripheral nervous system?

Afferent, efferent

Motor neuron cell bodies are in the _______ of the spinal cord.

Anterior horn of the gray matter

Describe the axon, including the number in each neuron, function, structure, and organelles.

Conducts nerve impulses away from the cell body to its axon terminals where it is emitted across a synapse to the dendrite of another neuron. Axons are composed of cells like the cell body but lack rough endoplasmic reticulum.

What does the DRG contain?

Contains the cell bodies of sensory neurons.

What neurotransmitter helps regulate emotional responses and muscle tone?

Dopamine

Sensory information travels into the spinal cord via the _______ of a nerve

Dorsal root

List the four types of support neuroglial cells in the central system and a function of each.

Ependymal cells: circulate cerebrospinal fluid and enable fluid exchange Oligodendrocytes: insulate CNS axons. Astrocytes: Wrap around blood capillaries and control the chemical environment. Microglial cells: protect the CNS, they break down dead cells and help identify and control infectious microorganisms.

What is the gray and white matter of the spinal cord?

Gray matter contains the cell bodies of neurons. The white matter of the spinal cord contains the axons of neurons.

These types of neurons are also called association neurons.

Interneurons

_____ neurons send messages from the central nervous system to the peripheral.

Motor neurons

The stretch reflex utilizes what type of specialized receptor to detect over-stretch?

Muscle spindles

Describe the function and site of synthesis and storage of neurotransmitters.

One of the main functions of the cell body is to manufacture neurotransmitters, which are chemicals stored in secretory vesicles at the end of axon terminals.When neurotransmitters are released by the axon terminal vesicles, they carry the transmission of the nerve impulse from one neuron to another.

Sensory neurons synapse on cells in the _______ of the spinal cord.

Posterior horn

Define the term reflex. Give an internal and an external example.

Reflexes are nearly instantaneous, automatic, involuntary motor responses to stimuli occurring inside or outside of the body. A subconscious reflex is the regulation of blood sugar by the hormones. An external example is touching a very hot object and immediately withdrawing your hand.

What are the four steps of an action potential in order?

Resting Potential, Depolarization, Repolarization, Afterpolarization (hyperpolarization). Sodium gates open and sodium rushes into the axon and the inside becomes more positive than the outside causing the membrane potential to become more positive.39. The sodium gates close and potassium gates open allowing potassium to rush out of the axon. This returns a negative charge to the inside of the axon re-establishing the negative potential.40. The potassium gates that open during repolarization are slow to close and there is an afterpolarization undershoot of the potential.

An axon's membrane is polarized with a resting potential of -70 mV. Explain what this means and what maintains this resting potential.

The axon plasma membrane is polarized, meaning that one side has a different charge than the other side. This difference called a resting potential means that the charge on the inside of the axon's cell membrane is 70 millivolts less than the outside of the membrane. A sodium- potassium pump using active transport carries ions across the plasma membrane and because three Na+ ions are pumped out as two K+ ions are pumped in a relative positive charge develops and is maintained on the outside of the membrane.

List the 5 components of a reflex arc.

The receptor, the afferent neuron, the integration center, the efferent neuron and the effector. 1) The receptor at the end of a sensory neuron reacts to a stimulus. 2) The sensory neuron conducts a nerve impulse along an afferent pathway towards the central nervous system. 3) The integration center houses one or more synapses in the central nervous system. 4) A motor neuron conducts a nerve impulse along an efferent pathway, which travels from the integration center to an effector. 5) An effector contracts a muscle or secreting from a gland.

What prevents continuous stimulation of a nerve synapse and how is this accomplished?

The short existence of neurotransmitters in the synapse prevents continuous stimulation. Some synapses contain enzymes that rapidly inactivate neurotransmitters and other synapses rapidly absorb the neurotransmitter.

What is controlled by the somatic and autonomic nervous systems?

The somatic system controls the movements of skeletal muscles, skin, and joints. The autonomic system nerves control the glands and smooth muscles of the internal organs.

What is the function of the sympathetic nervous system? What is the function of the parasympathetic nervous system?

The sympathetic nervous system activates for emergencies, high activity, and stress The parasympathetic nervous system is for normal daily functions such as resting, digesting, and energy conservation.