Chapter 7: The Peripheral Nervous System - Efferent Division

Chemicals used by the nervous system to send messages to the rest of the body; 50 different types; Two classifications (chemically, functionally)

Neurotransmitters

___ is  a cluster of neuronal cell bodies outside the CNS

Ganglion

The ___ innervates cardiac and smooth muscle, most exocrine glands, some endocrine glands and adipose tissue.

autonomic nervous system

The ANS release only two different ___ on the structure it controls: acetylcholine and norepinephrine

neurotransmitters

Each autonomic nerve pathway extending from the ___ to an innervated organ is a two-neuron chain. (with the exception being the__). Preganglionic to postganglionic.

CNS; adrenal medulla

An autonomic nerve pathway has two ___: preganglionic fiber and postganglionic fiber

Neurons

The cell body of the first neuron (on the two-neuron chain) is located in the CNS. Its axon, the ___, synapses with the cell body of the second neuron, which lies within a ganglion.

Preganglionic fiber

The axon of the second neuron, the___, innervates the effector organ.

postganglionic fiber

The two ___ of the ANS are the sympathetic and parasympathetic nervous systems

subdivisions

___ nerve fibers (axon portion of neuron) originate from the thoracic and lumbar levels of the spinal cord. Its preganglionic fibers are short. Its postganglionic fibers are long, terminating at effectors.

Sympathetic

___ nerve fibers originate from the cranial and sacral levels of the CNS. Its preganglionic fibers are long. Its post ganglion fibers are short, terminating at effectors. There are terminal ganglia near effector organs

Parasympathetic

Draw parasympathetic diagram

Draw parasympathetic diagram

An ___ is between the preganglionic and postganglionic fibers of an autonomic pathway. Act as a relay station. Not a fiber

autonomic ganglion

Both the parasympathetic and sympathetic ___ fibers release acetylcholine (ACh)

preganglionic

___ postganglionic fibers release ACh.

Parasympathetic

Preganglionic and postganglionic fibers that release ACh are called ___ fiber

cholinergic

Sympathetic postganglionic fibers release noradrenalin (commonly known as norepinephrine). They are ___ fibers.

adrenergic

Draw convoluted parasympathetic and sympathetic diagram

Draw convoluted parasympathetic and sympathetic diagram

The ANS controls the involuntary response of ___ (internal) organs. (ex: circulation and digestion to sweating and urination)

visceral

Innervation of a single organ by both branches of the autonomic system is known as ___. Visceral organs receive ___.

dual innervation

Usually both subdivisions are active in controlling the activity of an internal organ. This ongoing activity is called sympathetic or parasympathetic tone or ___.

Tone activity

The ___ dominates during the fight-or-flight response. (ex: pupils of the eye dilate, sweating is promoted, heart rate increases, bronchioles dilate, motility for digestion is inhibited, liver: conversion of glycogen into glucose, urination is inhibited). These responses prepare the body for emergency or stressful situations.

sympathetic

The ___ dominates during quiet, relaxed situations or null (ex: decreased heart rate or no activity of glucose production from the liver).

parasympathetic

___ allows the precise control over the activity of a visceral organ. Like having a gas pedal and brake pedal. Increased activity in one division is usually accompanied by a corresponding decrease in the other.

Dual reciprocal innervation

Dual reciprocal innervation exception: Most innervated ___ (arterioles and veins) receive only sympathetic nerve fibers. Regulation is accomplished by increasing or decreasing the firing rate above or below the tonic level in these sympathetic fibers.

blood vessels

Dual reciprocal innervation exception: Most ___ glands are innervated only by ___ nerves. Oddly, the sympathetic postganglionic fibers here secrete acetylcholine instead of their usual norepinephrine.

Sweat; sympathetic

Dual, reciprocal innervation exception: Both ANS subdivisions stimulate the activity of ___ glands. However, they fight over the ___’s composition and volume, whomever is more dominant wins.

salivary

The ___ are exocrine glands that rest above the kidney(s), with an outer portion and inner portion.

adrenaline glands

The ___ is the inner portion of the adrenaline gland. It is a modified sympathetic ganglion that does not give rise to postganglionic fibers. Instead, on stimulation by the preganglionic fiber that originates in the CNS, it secretes hormones into the blood. 20% of these hormones are norepinephrine and 80% are epinephrine (adrenaline)

adrenaline medulla

Each autonomic ___ binds to several different receptors.

neurotransmitter 

___ receptors respond to acetylcholine. The two types are nicotinic and muscarinic receptors.

Cholinergic

___ receptors are found on the postganglionic cells bodies of all autonomic ganglia. These ganglia are found where the preganglionic neurons signal the postganglionic neuron. Activated by tobacco plant derivative nicotine.

Nicotinic

___ receptors bind with ACh from the parasympathetic postganglionic nerve fibers. Are found on effector cell membranes (smooth muscle, cardiac muscle, and glands). Activated by the mushroom poison muscarine.

Muscarinic

___ receptors bind with norepinephrine and epinephrine from sympathetic postganglionic fibers. The two major classes are alpha and beta receptors.

Adrenergic

___ receptors usually produce an excitatory response in the effector. Present most in sympathetic target tissues.

alpha 1

___ receptors prefer norepinephrine over epinephrine, are found in digestive organs and usually produce an inhibitory response.

Alpha 2

___ receptors have equal affinity for norepinephrine and epinephrine. They are found mainly in the heart, and cause an excitatory response.

Beta 1

___ receptors bind almost exclusively with epinephrine and their activation generally produce an inhibitory response

Beta 2

Certain drugs selectively enhance or mimic autonomic response. They are ___

agonists

Other drugs block autonomic response. They are ___

antagonists

Autonomic activities are controlled by different areas of the ___. They include the spinal cord, medulla, hypothalamus, and prefrontal association cortex

CNS

The ___  nervous system signals skeletal muscles. One axon in its nerve from the spinal cord terminates on skeletal muscles

somatic

Draw diagram of somatic skeletal muscle thingie

Draw diagram of somatic skeletal muscle thingie

The axon terminates at a ___. The ___ is the specialized part of the muscle cell membrane facing the terminal button 

motor end plate

___ motor neurons affect skeletal muscle activity and bring about all body movement. Exclusively release acetylcholine, their neuromuscular junction neurotransmitter.

Somatic

Draw weird but familiar looking diagram

Draw weird but familiar looking diagram

___ (or bouton) refers to enlarged knoblike structure found at the end of axon terminal branches. They are essentially the same as synaptic bulbs (knobs) however the word synaptic is reserved for neuron to neuron connection.

Terminal button

The ENTIRE axon terminal ending (all the fine branches with terminal buttons) fits into a shallow depression, or groove, in the underlying muscle fiber. This specialized underlying portion of muscle cell membrane is called the ___.

motor end plate

An action potential at the axon terminal opens voltage-gated calcium channels in the terminal button (synaptic knob, or synaptic bulb). Calcium diffused into the terminal button from the ECF. By this calcium influx, acetylcholine is released by exocytosis from vesicles in the terminal buttons. Acetylcholine diffuses through the space between the nerve cell and muscle cell. This neurotransmitter binds to receptor sites on the motor end plate of the muscle cell membrane. This binding opens channels for sodium influx into the ICF of the muscle cell. This produces a local current flow that opens adjacent sodium channels in the motor end plate. An action potential is initiation through the muscle fiber.

Neuromuscular junction

___ destroys acetylcholine. This terminates the action potential and response of the muscle cell.

Acetylcholinesterase

The neuromuscular junction is vulnerable to several ___ and__.

chemical agents; disease

___, a toxin, blocks the release of acetylcholine from the terminal button in response to a motor neuron action potential, resulting from specific food poisoning. Respiratory failure caused by inability to contract the diagram.

botulinum toxin

___, a toxin, triggers explosive release of ACh from the storage vesicles at all cholinergic sites. The prolonged depolarization, not stopping for resting potential to be reached. The most harmful result being respiratory paralysis.

black widow spider venom

___ block the effect of released acetylcholine. It is an antagonist which reversely binds to the ACh receptor channel on the motor end plate. Causing paralysis, enough can paralyze the respiratory system.

Curate