4 - Autonomic Systems

Question 1

What is the function of the autonomic nervous system?What are examples of this function?

Answer 1

Central and peripheral portions of the NS designed to harmonize bodily functions with brain state.

BP, HR, digestion, urination, and thermoregulation.

Question 2

What are the two polarities of the ANS?

Answer 2

Rest and digest: parasympathetic

Fight or flight: sympathetic

Question 3

How do the parasympathetic and sympathetics ANS work most often? Give examples.

Answer 3

Most often coordinate together.

Cooling: sweating and skin dilation
Voiding: detrusor and trigone
Fainting: hypotension and bradycardia

Question 4

How is the autonomic nervous system organized?

Answer 4

Cranial parasympathetic outflow: above T1
Pelvic parasympathetic outflow: S2-S4

Sympathetic outflow: T1-L2

Question 5

In terms of autonomic function, what are two important spinal levels to consider?

Answer 5

Lesions above T6 result in BP problems such as orthostatic hypotension: splanchnic circulation innervation

Lesions at S1 are above are upper motor neurons involved in bladder/bowel. Lower motor neurons are S2-4.

Question 6

What is the outflow for the PNS and SNS?

Answer 6

PNS: cranio-sacral

SNS: thoracolumbar

Question 7

What is the preganglionic pharmacology of the PNS and SNS?

Answer 7

PNS: nicotinic cholinergic

SNS: nicotinic cholinergic

Question 8

What is the postganglionic pharmacology of the PNS and SNS?

Answer 8

PNS: muscarinic cholinergic

SNS: Noradrenergic

Question 9

What are the co-released agents in the PNS and SNS?

Answer 9

PNS: vasoactive intestinal peptide, calcitonin gene-related protein (CGRP)

SNS: Neuropeptide Y (NPY), neurotensin

Question 10

What is the function of the PNS in a non-threatened and a threatened state?

Answer 10

Non-threatened: daily end-organ modulation

Threatened: allows SNS to lead

Question 11

What is the function of the SNS in a non-threatened and a threatened state?

Answer 11

Non-threatened: coordinate under PNS lead

Threatened: coordinate emergent readiness

Question 12

Describe the ganglion associated with the PNS and the SNS?

Answer 12

PNS: close to end-organ; not much cross-organ orchestration.

SNS: in sympathetic chain close to sp cd; extensive cross-organ coordination

Question 13

What are the primary roles of the PNS and SNS?

Answer 13

PNS: neurons synapse on SNS neurons and provide control for PNS over SNS.

SNS: when in concert, yields to PNS; however, many areas innervated by SNS only such as vessels and sweat glands.

Question 14

Describe the response speed of the PNS and SNS?

Answer 14

PNS: fast <1 second

SNS: slow, several seconds

Question 15

What is an autonomic disorder?

Answer 15

Defined in adult as a condition in which the patient experiences altered autonomic function that adversely affects health.

Question 16

What are the two central autonomic control centers?

Answer 16

Hypothalamus and PAG.

They receive input from farther up.

Question 17

What does every patient that falls have?

Answer 17

An orthostatic BP taken on them (lying, sitting, standing).

Question 18

What is orthostatic hypotension?

Answer 18

Form of low pressure that occurs when you sit or stand from a lying position.

Can make you feel dizzy, lightheaded, or make you faint.

Question 19

What symptom is commonly absent in pts with structural autonomic disorders?

Answer 19

Lightheadedness.

Question 20

What are characteristics of a structural ANS disorder? What are examples of structural ANS disorders?

Answer 20

Think hardware
-Well-defined changes in ANS structure producing disease

Exp: multiple system atrophy, diabetic autonomic neuropathy, baroreflex failure due to neck radiation.

Question 21

What are characteristics of a functional ANS disorder? What are examples of funcitonal ANS disorders?

Answer 21

Think software

• change in ANS function produces symptoms, but is:
  (1) less well-defined and
  (2) a link in a pathogenic chain but not primary

Emp: postural tachy syndrome (POTs), IBS, and syncope

Question 22

What is the function of the baroreflex?

Answer 22

Pressure sensors in the aortic arch, carotid sinus, and sinus node that serve as a way for the brain to monitor and adjust BP.

Question 23

Why do we develop orthostatic intolerance?

Answer 23

75% of our blood volume is below our heart level, this differs from many other animals.

This makes it difficult to return blood to our heart and get blood to our brain.

Question 24

What afferent input is involved in thermoregulation? What modulates the set-point control of temperature?

Answer 24

Afferent input: anterior hypothalamus

Setpoint control: VIP, IL-6, IL-2, PGE2

Question 25

What two things are involved in thermoregulation?

Answer 25

Anterior hypothalamus: cooling

Posterior hypothalamus: warming

Question 26

What is the ascending control of thermoregulation?

Answer 26

Behavior: moving to a cooler or warmer environment, putting on a sweater

Question 27

What are the descending controllers of thermoregulation?

Answer 27

lateral horn: skin vessels, sweat glands, brown fat

Anterior horn: motor (shivering)

Brainstem: respiratory rate

Anterior pituitary: thyroid stimulation

Question 28

What results from a hypothalamic lesion in the suprachiasmatic nucleus? What is the function of this space? What can cause this?

Answer 28

Function: regulates circadian rhythm

Lesion: causes insomnia

Can be caused by Alzheimer’s disease or shift-work

Question 29

What is the function of the anterior nucleus of the hypothalamus? What results from lesions here? What mediates this?

Answer 29

Function: dissipates heat

Lesion: causes hyperthermia

Endogenous pyrogens such as IL-2 and PGE2 cause fever.

Question 30

What is the function of the medial hypothalamus? What results from lesions here? What are examples of this?

Answer 30

Regulates feeding behavior (stops overeating).

Lesion causes overeating and obesity.

Prader-willi syndrome, craniopharyngioma.

Question 31

What can the hypothalamus be thought of? What about the periaqueductal gray?

Answer 31

Hypothalamus: It’s the chief internal environment operating officer

PAG: chief external environment operating officer

Question 32

What is the function of the PAG?

Answer 32

Implements basic behavioral mode to determine if something is safe or a threat.

Safe: sleep, wake, urination.
Threatening: determine if threat is escapable or inescapable

Question 33

What is the so-called CFO and COO of the brain? What is their function?

Answer 33

CFO: insula, manages everything (like the dashboard on a 747)

COO: amygdala: provides urgency

Question 34

What provides input to the PAG?

Answer 34

The hypothalamus, amygdala, the prefrontal and anterior cingulate cortices, anterior insula and orbitofrontal cortex.

Question 35

What does the PAG receive info to determine? What does it get afferent from?

Answer 35

Whether something is safe or a threat.

Info from nociceptors and visceral afferents.

Question 36

What parts of the PAG are involved in a controllable treat? What about a non-controllable threat?

Answer 36

Controllable: DL and L

Non-controllable threat: VL
-says you’re going to die and creates complete analgesia, drop in HR and BP, and paralysis.

Question 37

What changes occur in your body if the threat is determined to be controllable?

Answer 37

HTN and tachy, extracranial vasodilation, and hindlimb and renal vasoconstriction.