Autonomic Nervous System Lecture Powerpoint

Question 1

2 components of autonomic NS, what is the primary neurotransmitter associated with it, and what are the receptors associated with it?

Answer 1

• Sympathetic/thoracolumbar (norepi, adrenergic)

- Parasympathetic/craniosacral (acetycholine, cholinergic)

Question 2

General functions of ANS (2)

Answer 2

• motor innervation to glands, cardiac, and smooth muscle (visceral motor system)
• unconscious homeostasis (BP, body temp, etc)

Question 3

2 Examples of cooperative effects of SANS and PANS

Answer 3

• Erection occurs by parasympathetic division, ejaculation occurs via sympathetic division
• parasympathetic NS increases salivary serous cell secretion, sympathetic increases salivary mucous cell secretion (thicker, stringy mucus)

Question 4

Example of opposing effects of SANS and PANS

Answer 4

Sympathetic NS activity increases heart rate, while parasympathetic NS activity slows heart rate

Question 5

Somatic vs autonomic pathways of efferent innervation

Answer 5

ANS has 2 neurons opposed to one that span distance form CNS to effectors with presynaptic neuron cell body in CNS followed by a myelinated preganglionic fiber (same as somatic) that then transfers to a postsynaptic neuron cell body which carries the rest of the signal thru an unmyelinated postganglionic fiber to the target organ

Question 6

In sympathetic division, pregangionic fibers tend to be very ___ and postganglionic tend to be very ___. In parasympathetic division, preganglionic are very ___ and post are very ___

Answer 6

short, long, long, short

Question 7

Adrenal medulla function (include what percentage of released catecholamines are epi vs norepi)

Answer 7

Very large modified sympathetic ganglion that receives pregangionic innervation and is stimulated to release epi (80%) and norepi (20%) into the body, causes prolonged activity of the substances, helps the body deal with stress, takes longer to metabolize from body leading to prolonged “keyed up” feeling

Question 8

Results of increased SANS stimulation (7)

Answer 8

• increased heart rate and force
• dilation of blood vessels in cardiac and skeletal muscle
• constriction of blood vessels in intestinal tract/kidneys/nonessential areas
• dilation of airways
• glycogen breakdown/fat cell breakdown
• body temp rises
• dilation of pupil (mydriasis)

Question 9

Cranial nerves are classified as ____ _____ nerves, which is the most important one?

Answer 9

• Autonomic parasympathetic

- Vagus nerve (X), responsible for majority of parasympathetic stimulation to different viceral systems of the body

Question 10

Results of increased PANS stimulation (5)

Answer 10

• heart rate slows
• GI tract increases digestion and contraction
• bladder and bowel emptying
• eye focusing on near vision (miosis)
• bronchial smooth muscle contraction

Question 11

Parasympathetic fibers tends to elicit very ____ responses

Answer 11

localized

Question 12

Dual innervation

Answer 12

Refers to tendency of most viscera of the body to receive nerve fibers from both parasympathetic and sympathetic divisions that often have antagonistic effects or occasionally cooperative effects desppite not normally innervating the organ equally

Question 13

Dual innervation of the iris (don’t forget the names of the muscles that perform the actions!)

Answer 13

The radial muscle is controlled by the sympathetic NS, stimulation sees contraction causing pupilary dilation (mydriasis) while parasympathetic stimulates the circular muscles, stimulation causes constriction of pupil (myosis)

Question 14

Control without dual innervation

Answer 14

Certain areas of the body that only receive predominantly one type of innervation

Question 15

Examples of control without dual innervation (4)

Answer 15

• adrenal medulla
• erector pili muscles
• sweat glands
• vasomotor tone (only has sympathetic as baseline, with increased firing of stretch receptors causing constriction and decreased causing dilation)

Question 16

CNS controllers of autonomic function (4)

Answer 16

• limbic system (emotions)
• hypothalamus (primitive functions like hunger and sex)
• reticular formation and brainstem nuclei
• spinal cord reflex inhibition/activation (such as defacation and micturition)

Question 17

2 major neurotransmitters of ANS, what releases them, and where are they found

Answer 17

• acetylcholine: released by cholinergic neurons to all pre ganglionic neurons and postganglionic parasympathetic neurons)
• norepi: released by adrenergic neurons from postganglionic sympathetic neurons

Question 18

On rare occasion such as in the stimulation of sweat glands we see….

Answer 18

….release of acetycholine from postganglionic sympathetic nerve fibers (very uncommon in other parts of body mostly only release norepi)

Question 19

Effect of a neurotransmitter on any postsynaptic cell is determined by the characteristics of…

Answer 19

….the receptor, NOT the neurotransmitter

Question 20

3 types of cholinergic receptors

Answer 20

Nicotinic type I and type II and muscarinic

Question 21

4 types of adrenergic receptors

Answer 21

alpha 1 and alpha 2 and B1 and B2 receptors

Question 22

a1 vs a2 vs B receptor functional 2ndary messenger systems

Answer 22

• a1 receptors utilize Ca2+ as a secondary messenger
• a2 receptors suppress cyclic AMP as a 2ndary messenger
• B receptors activate cyclic AMP as a 2ndary messenger

Question 23

a1 adrenergic receptors

Answer 23

Bound by catecholamines (epi or norepi), found on virtually all sympathetic target organs, sees vasoconstriction of vascular smooth muscle, ejaculation, contraction of bladder neck and prostate, and pupillary dilation

Question 24

a2 adrenergic receptors

Answer 24

Bound by catecholamines (epi or norepi), located in synaptic cleft between target organ and post synaptic neuron where upon being bound it inhibits its further release of catecholamines

Question 25

B1 adrenergic receptors

Answer 25

Bound by catecholamines (epi or norepi), located at the heart causes increased heart rate, force of contraction, and increased velocity of conduction to AV node, as well as stimulates renin release at the JG cells of the kidney
(think about B blockers Tav)

Question 26

B2 adrenergic receptors

Answer 26

Bound only by epi, seen in the lungs to cause bronchial dilation, uterine muscle relaxation (premature labor prevention with drugs), coronary and skeletal muscle blood vessels vasodilation, stimulate glycogenolysis

Question 27

Dopamine receptors

Answer 27

Bind dopamine released from adrenergic neurons in the kidney that then dilates renal blood vessels to increase blood flow to kidney

Question 28

catechol-o-methyl-transferase (COMT) and monoamine oxidase (MAO)

Answer 28

• COMT functions to breakdown circulating NE and Epi in tissues thruout the body
• MAO functions to desrtroy NE released from adrenergic nerve fibers reabsorbed into the presynaptic nerve ending

Question 29

Nicotinic type I receptors

Answer 29

Bound by acetycholine, found in the autonomic ganglia in both divisions of the ANS between pre and post ganglionic fibers as well as in the adrenal medulla

Question 30

Nicotinic type II receptors

Answer 30

Bound by acetycholine, found in the somatic nervous system on motor end plates of skeletal muscle acting excitatory

Question 31

Muscarinic receptors

Answer 31

Bound by acetylcholine, found on all target tissues of parasympathetic NS, either excitatory or inhibitory when ACh binds depending on subclass of muscarinic receptors

Question 32

Acetylcholinesterase

Answer 32

Enzyme responsible for Ach degradation in the synaptic cleft causing parasympathetic stimulation to have a short duration of effect

Question 33

Sympathetic responses tend to be widespread for these 2 reasons

Answer 33

• neuronal divergance to many organs from preganglionic to postganglionic fibers having a ratio of 1:17
• release of epi and norepi from adrenal gland into blood stream

Question 34

Sympathetic and parasympathetic divisions influnce the ____ NS thru autonomic reflexes, even though this system can function independently thru local reflexes

Answer 34

Enteric