Ch. 16: Autonomic Nervous System

Autonomic Nervous System Image

Peripheral nerves control

both motor and sensory neurons

2 types of motor neurons

somatic and autonomic

Somatic system controls what muscles vs. autonomic system controls what muscles?

Somatic: skeletal muscles
Autonomic: smooth and cardiac, glands

Sensory neurons are not divided into somatic and autonomic, but

there is still an overlap in function

Sympathetic and parasympathetic systems often supply the same organs, but

their function differs

Somatic vs. Autonomic NS

Table 16.1 - Comparison of the Somatic and Autonomic Nervous Systems

"stimulated and inhibited"
"postganglionic axons are unmyelinated"

Which of the following is NOT an effector controlled by the autonomic nervous system?
A. cardiac muscle
B. skeletal muscle
C. glands
D. smooth muscle in blood vessels

B. skeletal muscle

3 divisions of the Autonomic Nervous System

1. Sympathetic (thoracolumbar) - prepares body for physical activity
2. Parasympathetic (craniosacral) - (controls veg. functions like digestion, defecation, & urination)
3. Enteric (digestive system)

Sympathetic (Thoracolumbar) Division consists of

preganglionic cells bodies in the lateral horns of T1-L2

Preganglionic axons pass through ___ to ___

ventral roots to white rami

What does the white rami communicate with?

the retroperitoneal sympathetic chain ganglia

Sympathetic chain (or paravertebral) ganglia

How do the sympathetic nerves connect to:
- smooth muscle?
- cardiac muscle?
- gland tissue?

4 routes of sympathetic axons as they exit the sympathetic chain ganglia

1. Spinal nerves
2. Sympathetic nerves
3. Splanchnic nerves
4. Innervation to the adrenal medulla

Spinal nerve route (Skn/Sk. M.)

Preganglionic axons synapse with postganglionic neurons within sympathetic chain.

These postganglionic neurons exit ganglia through the gray rami, which communicates and re-enters spinal nerves.

Sympathetic nerve route (organs in thoracic cavity)

Preganglionic axons synapse with postganglionic neurons, which exit the ganglia through sympathetic nerves to the heart.

Splanchnic nerve route (effectors in abdominopelvic cavity)

Preganglionic axons pass through ganglia without synapsing and are carried out via splanchnic nerves.

Then they synapse with postganglionic neurons in collateral ganglia.

Postganglionic neurons then innervate organs.

Innervation to adrenal medulla route

Preganglionic axons synapse with the cells of the adrenal medulla, which then releases Ep and NE (hormones that prepare for physical activity)

T or F: the adrenal medulla developed from the same cells as postganglionic ANS cells

true

Distribution of Sympathetic ANS Fibers (Sympathetic axons reach organs through: 3 things, and what they innervate)

1. Spinal nerves, head and neck nerve plexuses: sweat glands, smooth muscle of blood vessels to skeletal muscle and skin, & arrector pili
2. Thoracic nerve plexuses: cardiac and pulmonary systems
3. Abdominopelvic nerve plexuses: celiac organs (diaphragm, stomach, spleen, etc.), mesenteric organs, (colon, pancreas, small intestine), and other organs of the abdominopelvic cavity

Sympathetic fibers leave the spinal cord in the
A. cranial and sacral regions.
B. lumbar and sacral regions.
C. cranial and thoracic regions.
D. thoracic and lumbar regions.

D. thoracic and lumbar regions.

Parasympathetic (craniosacral) division

preganglionic cell body nuclei are in the brainstem or lateral gray matter in the spinal cord from S2-S4

In the parasympathetic division, preganglionic axons go through cranial nerves to _____.

terminal ganglia (through CN III, VII, IX and X).

In the parasympathetic division, preganglionic axons from sacral region go through ___ to ___.

pelvic splanchnic nerves to terminal ganglia

Why are terminal ganglia located near or on the effector organ in the parasympathetic division?

So the postganglionic axon has only a short distance to go to its effector

Distribution of Parasympathetic ANS Fibers (Parasympathetic axons reach organs through: 4 things and what they innervate)

1. Cranial nerves (oculomotor - III: ciliary ganglion->ciliary and iris muscles & facial - VII: pterygopalatine ganglion/submandibular ganglion->lacrimal and salivary glands) supplying the head and neck
2. Vagus nerve (X) & thoracic nerve plexus to heart & lungs
3. Abdominopelvic nerve plexuses & parts of vagus to stomach & other viscera
4. Pelvic splanchnic nerves and nerve plexuses to colon, urinary bladder, & reproductive organs.

The enteric nervous system consists of

nerve plexuses within wall of digestive tract

The enteric nervous system has contributions from 3 sources:

1. Sensory neurons (digestive tract -> CNS)
2. ANS motor neurons (CNS -> digestive tract)
3. Enteric neurons (confined within enteric plexuses)

2 functions of the enteric NS (bc it can control the digestive tract independent of the CNS)

1. Stimulate/inhibit smooth muscle and gland secretions.
2. Detect changes in contents of the lumen (GI tract cavity for digestive food)

Arrange the following in correct sequence:
1) autonomic ganglia and ganglionic synapse
2) synapse with target tissues
3) preganglionic neuron
4) postganglionic neuron 

A. 2, 3, 4, 1
B. 1, 3, 2, 4
C. 3, 1, 4, 2
D. 4, 1, 3, 2

C. 3, 1, 4, 2

What are neurotransmitters produced by in the ANS?

its neurons (neurons of the sympathetic and parasympathetic systems)

What type of neurons is acetylcholine released by?

cholinergic neurons

What type of neurons is norepinephrine released by?

adrenergic neurons

What two different forms of cholinergic receptors bind acetylcholine?

nicotinic and muscarinic

Where are nicotinic receptors located? (3 places)

1. in the membranes of all postganglionic neurons in autonomic ganglia
2. in the membranes of skeletal muscle cells
3. on the cell bodies of autonomic postganglionic neurons in the autonomic ganglion

What effect does the binding of ACh to a nicotinic receptor have?

an excitatory effect

Where are muscarinic receptors located? (2 places)

1. the membranes of effector cells that respond to ACh released from postganglionic neurons.
2. on the cells of all parasympathetic effectors & some Sympathetic effectors, such as sweat glands

What effect does the binding of ACh to a muscarinic receptor have?

either excitatory or inhibitory

What do adrenergic receptors bind? (2 things)

norepinephrine and epinephrine

Where are adrenergic receptors located?

on most sympathetic effectors

What effect does the binding of NE to a adrenergic receptor have?

either excitatory or inhibitory effect (ex. Bl V.)

What 2 receptors are adrenergic receptors further subdivided into?

alpha and beta receptors

What neurotransmitter has a greater effect on alpha and beta receptors?

Epinephrine

Location of ANS Receptors image

Table 16.3a - Effects of the Sympathetic and Parasympathetic Divisions on Various Effectors

Table 16.3b - Effects of the Sympathetic and Parasympathetic Divisions on Various Effectors

"thick organic secretion"
"watery sweat from most of the skin (m), sweat from palms and soles (a1)
"dilated air passageways (B2)"
"constricted air passageways"

Which of the following is a sympathetic effect?
A. constriction of the pupils of the eye
B. decreased heart rate
C. dilation of the bronchioles in the lungs
D. increased gastric secretions

C. dilation of the bronchioles in the lungs

Adrenergic receptor stimulant and what it does

Albuterol dilates bronchioles in lungs

Adrenergic receptor blocking agents and what it does

Lopressor treats high blood pressure

Regulation of the ANS

autonomic reflexes control most of the activity of visceral organs, glands and blood vessels, but autonomic reflex activity is influenced by the hypothalamus and higher brain centers.

The hypothalamus has overall control of the ANS.

The results of adrenal medulla secretions (Ep and some NE) on target tissues (8 things)

1. Increased glucose release from liver into blood
2. Increased release of fatty acids from adipose tissue into the blood
3. Increased HR
4. Decreased blood flow through most internal organs
5. Increased blood flow to skeletal muscles and the heart
6. Increased BP
7. Decreased function of visceral organs
8. Increase MR of skeletal muscles

2 autonomic reflexes and their effects

1. Parasympathetic reflex via vagus lowers heart rate
2. Sympathetic reflex via cardiac nerve (sympathetic nerve to heart) causes increased heart rate

Parasympathetic reflex via vagus image

Sympathetic reflex via cardiac nerve image

Enteric NS autonomic reflex

sensory neurons of the enteric plexuses supply CNS with information

Enteric NS local reflex

does not involve CNS, it produces an involuntary and unconscious response

Example of a local effect in the enteric NS

the stretch of the wall of the digestive tract is detected by sensory neurons (Ind. of CNS), which send APs that lead to contraction or relaxation of smooth muscle

What has overall control of Autonomic Nervous System?
A. pituitary gland.
B. cortex of the brain.
C. cranial and thoracic regions of spinal cords.
D. hypothalamus.

D. hypothalamus.

Functional Generalizations of ANS

1. Dual innervation (ex: GI tract, heart, urinary bladder)
2. Opposite effects (ex: sympathetic -> physical activity, parasympathetic -> rest - SLUDD)

What is the exception to the sympathetic ANS regulating functions needed for physical activity?

BP: Blood vessel walls only have sympathetic stimulation - at rest, sympathetic is responsible for maintenance of BP

What does SLUDD stand for?

salivation
lacrimation
urination
digestion
defecation

Sympathetic vs. Parasympathetic image

Responses to exercise (fight or flight) - 7 things

1. Increased heart rate and force of contraction
2. Blood vessel dilation in skeletal/cardiac muscles
3. Dilation of air passageways (bronchial tubes)
4. Energy sources availability increased (ex: glycogen -> glucose & the breakdown of triglycerides by fat cells to free fatty acids)
5. Muscles generate heat to increase body temperature
6. Sweat gland activity increases
7. Decrease in nonessential organ activities

Reynaud's disease image

extremities turn white then blue

Acetylcholine is used as a neurotransmitter substance in this system.
A. somatic motor nervous system
B. autonomic nervous system
C. both somatic and autonomic nervous system
D. neither somatic nor autonomic nervous system

C. both somatic and autonomic nervous system

Target tissues may be stimulated or inhibited.
A. somatic motor nervous system
B. autonomic nervous system
C. both somatic and autonomic nervous system
D. neither somatic nor autonomic nervous system

B. autonomic nervous system

Increases activity of GI tract.
A. Sympathetic
B. Parasympathetic

B. Parasympathetic

Can produce widespread sweating.
A. Sympathetic
B. Parasympathetic

A. Sympathetic

Release of epinephrine and norepinephrine.
A. Sympathetic
B. Parasympathetic

A. Sympathetic

Craniosacral division.
A. Sympathetic
B. Parasympathetic

B. Parasympathetic

Vegetative functions.
A. Sympathetic
B. Parasympathetic

B. Parasympathetic

The vagus (X) nerve carries parasympathetic impulses to the
A. salivary glands.
B. lacrimal glands.
C. smooth muscle of the eyes.
D. thoracic and abdominal viscera.

D. thoracic and abdominal viscera.

Short answer: It is final exam time. You need a B to keep your B+ in the class.

What physiologic changes, mediated by the autonomic nervous system, might you be exhibiting as you take the final exam? 

Increase in sympathetic activity resulting in increased heart rate, increased blood pressure, sweating, vasoconstriction of peripheral blood vessels causing the skin to be cold, increased metabolism, dilated bronchi, more glucose released into the blood, and a decrease in gastrointestinal activity.