Chapter 4: Visceral Nervous System

What is the viscera?

internal organs/core, blood vessels, structures in the skin

What is the term for visceral afferent fibres?

general visceral afferent (GVA)

What is the function of GVAs?

sensory info from core/internal organs to CNS

What is the term for visceral efferent?

general visceral efferent (GVE)

What is the function of GVEs?

control smooth muscle, cardiac muscle, and secretory glands WITHOUT CONSCIOUS CONTROL = ANS

What is the ANS?

a division of the visceral PNS that divides into the parasympathetic and sympathetic systems

Where does the parasympathetic system innervate?

the core

"calm core"

Where does the sympathetic system innervate?

both the core and the periphery

"panicked periphery and core"

What is the function of the enteric nervous system?

gut motility

Visceral nociceptors are responsible for ...

pain

primarily T1-L2 and S2-S4

What is the function of visceral mechanoreceptors?

fullness

What are specialized receptors in the visceral receptors?

blood pressure

Where do signals originate for the ANS?

originate in hypothalamus and travel out, influenced by reticular formation and amygdala

Describe the integration of cognitive and emotional functions with visceral nerves

mental, emotional, visceral, and environmental influences can alter visceral motor function

Is the ANS afferent or efferent?

it is efferent = the visceral motor system

The sympathetic nervous system is housed where?

lateral horn T1-L2

The parasympathetic nervous system is housed where?

brainstem and S2-S4

"para to the sympathetic" (para meaning beside or on the outskirts of)

What are other names for the parasympathetic nervous system?

craniosacral system (because of where it lies)

"rest and digest"

What are the cranial nerves involved in the parasymp ns?

-III (pupils constriction)

-VII tears, nasal

mucus, saliva,

-IX parotid salivary gland

-X visceral

organs of thorax & abdomen

What neurotransmitter is at the target organ creating the term "cholinergic" system?

ACh

What are other names for the sympathetic system?

thoracolumbar system (all neurons are in lateral horn of T1-L2)

fight, flight, fright

What is the neurotransmitter released by postganglionic sympathetic fibers?

norepi

What is the neurotransmitter from the preganglionic and postganglionic fibers to the periphery?

ACh

Summary of sympathetic stimulation

-pupil dilation

-saliva production reduced

-musuc production reduced

=HR and force increase

-bronchial muscle relaxed

-peristalsis reduced

-gut motility reduced

-increased conversion of glycogen to glucose

-decreased urine secretion

-NE and EPi secreted

-bladder wall relaxed and sphincter closed

Parasympathetic Summary

-pupil constriction

-saliva production increased

-mucus production increased

=HR and force decreased

-bronchial muscle contracted

-digestion increased

-gut motility increased

-increased urine secretion

-bladder wall contracted and sphincter relaxed

What are the most important functions of the ANS?

-circulation

-respiration

-digestion

-metabolism

-secretions

-body temperature

-reproduction

What is allostasis?

maintenance of homeostasis when changes occur in body

Can the enteric nervous system still function when the vagus nerve is severed?

yes

Fun facts about the enteric nervous system

• The enteric nervous system also makes use of more than 30 neurotransmitters, most of which are

identical to the ones found in the CNS, such as acetylcholine, dopamine, and serotonin.

• Nearly 90% of the body's serotonin and 50% of the dopamine is in the gut

What is a reflex arc?

a neural pathway involved in a reflex

What are the 5 components of a reflex arc?

1. Sensory receptor

2. sensory neuron

3. integration center

4, motor neuron

5. effector target

What are visceral reflexes?

those which involve a glandular or non-skeletal muscular response

- use neurons of the ANS to elicit actions

What is an example of a nonconscious visceral reflex?

control of BP

What is the name for pressure receptors in the carotid and aortic sinuses?

baroreceptors

What is the function of baroreceptors?

provide info to the cardiovascular center in the medulla oblongata about the degree of stretch with pressure changes

What is the system when the baroreceptors detect a rise in BP?

- vasodepressor response via vagus nerve to generate a parasympathetic response in the heart

What is the system when the baroreceptors detect a drop in BP?

-vasopressor system via sympathetic reflex circuit

Bladder control is an example of how which two systems work together?

somatic and visceral

What are afferent bladder sensations?

somatic: pain and temperature

visceral: bladder fullness

What are efferent bladder functions?

internal sphincter = non-conscious sympathetic

detrusor muscle = non-conscious parasympathetic efferent

external urethral sphincter = conscious somatic motor efferents

What coordinates the reactions of the bladder control?

central nuclei in pons and forebrain

What is the process of micturition?

- urine is made in the kidneys

- urine stored in bladder

- sphinceter muscles relax

- bladder (detrusor) contracts

- bladder is emptied through urethra and urine removed from body

What kind of muscle is the detrusor muscle in the bladder?

smooth muscle with interlaced bands

The sympathetic ANS works to _______ the detrusor to fill the bladder

suppress contraction

The parasympathetic ANS works to cause the detrusor to ________ and empty

contract

What is the normal position of the internal sphincter?

normally closed

The hypogastric nerve contributes to urinary continence, what fibers contribute to this?

sympathetic

The external sphincter is made of striated muscle and is under _______ control by the _______ nerve of the ventral horns

under voluntary control by the pudendal nerve