Autonomic nervous system

Question 1

Overall function of ANS

Answer 1

•Homeostasis: Maintaining a stable internal environment amid changing external conditions

Question 2

ANS vs. somatic motor system

Answer 2

ANS is: Involuntary (vs voluntary), Diffuse projections (vs specific projections), Slow action (vs rapid), Innervates smooth and cardiac muscle, and gland cells (vs. skeletal muscle), Disynaptic (vs Monosynaptic)

Question 3

Which fibers are fast and which are slow, preganglionic or postganglionic?

Answer 3

preganglionic are myelinated and fast. Postganglionic are unmyelinated and slow

Question 4

Inputs to the ANS

Answer 4

Nucleus of solitary tract conveys visceral sensory input, other brainstem nucle convey environmental stimuli, hypothalamus conveys internal states

Question 5

3 subdivisions of ANS

Answer 5

Sympathetic, parasympathetic and enteric (semi-autonomous control of digestion)

Question 6

Anatomy of sympathetic NS

Answer 6

•Preganglionic neurons originate in thoracic and lumbar spinal cord, Ganglia located near spinal cord(sympathetic trunk), 1:10 ratio of pre- to post-ganglionic neurons

Question 7

Anatomy of parasympathetic NS

Answer 7

•Preganglionic neurons originate in brainstem and sacral spinal cord, Ganglia located near target organs, 1:3 ratio of pre- to post-ganglionic neurons

Question 8

Sympathetic neurotransmitters and receptors

Answer 8

Ach is released from preganglionic neuron, binds to nicotinic receptor on postganglionic neuron. Postganglionic neuron releases norepinephrine and epinephrine which bind to alpha and Beta adrenergic receptors on the organ

Question 9

Parasympathetic neurotransmitters and receptors

Answer 9

Ach is released from preganglionic neuron, binds to nicotinic receptor on postganglionic neuron. Postganglionic neuron releases Ach which binds to muscarinic receptor on organ.

Question 10

Compare nicotinic and muscarinic Ach receptors

Answer 10

Nicotinic is ligant-gated cation channel that opens and leads to depolarization. Muscarinic is liked to a G protein which can cause depolarization or hyperpolarization depending the type of muscarinic receptor

Question 11

Vasodilation and constrictions are mainly controlled by?

Answer 11

sympathetic NS- increased SNS causes vasoconstriction and decreases SNS causes vasodilation

Question 12

SNS vs PSNS affect on blood pressure

Answer 12

SNS: increases blood pressure (increases HR, contractile force and constriction of blood vessels). PSNS: decreases BP (decreases HR and contractile force)

Question 13

What was the Loewi experiment

Answer 13

First identification of chemical neurotransmission: two hearts were connected by a pump and the first heart was stimulated. The second heart had same HR as first heart

Question 14

What is Atropine?

Answer 14

Sympathomimetic drugs – mimic sympathetic activation. Acts as a muscarinic antagonist in heart to increase HR

Question 15

What is Propranolol?

Answer 15

•Parasympathomimetic drugs – mimic parasympathetic activation. Acts as beta adrenergic antagonist in heart to decrease HR

Question 16

Describe humoral regulation from hypothalamus

Answer 16

Hormones are made in hypothalamus then released into the pituitary. Posterior pituitary is a direct extension of hypothalamus axons. Anterior pituitary is a gland

Question 17

Vasopressin- released from where? Results in?

Answer 17

Aka ADH. Released from posterior pituitary in response to low blood pressure detected by subfornical organ. Causes vasoconstriction and Acts on kidneys to increase water retention

Question 18

Renin- Released from where? Function?

Answer 18

Released from kidneys in response to low BP. Converts Angiotensinogen to Angiotensin I

Question 19

Angiotensin II - functions

Answer 19

Constricts blood vessels, increases water retention in kidney, activates neurons in subfornical organ

Question 20

The adrenal medulla functionally is a ___________

Answer 20

sympathetic ganglion

Question 21

What does adrenal medulla do?

Answer 21

Innervated by preganglionic sympathetic neurons and releases NE and epi into blood, with widespread sympathomimetic effects. NE and epi thus become hormones that regulate activity of disant tissues

Question 22

Which neurotransmitter can activate all 4 subtypes of adrenergic receptors?

Answer 22

Epinephrine from adrenal medulla- activates alpha 1,2 and beta 1,2

Question 23

Explain baroreceptor reflex

Answer 23

low blood pressure leads to increased sympathetic output. High blood pressure leads to increased parasympathetic output

Question 24

CV related action of agonists of adrenergic receptors: alpha1, alpha2, Beta1, beta 2

Answer 24

alpha1: vasoconstriction in skin. Alpha 2: presynaptic inhibition of NE release and some vasoconstriction. Beta1: increased HR. Beta2: incrased HR, vasodilation in skeletal muscle

Question 25

“head ganglion”

Answer 25

hypothalamus

Question 26

Why is hypothalamus called the head ganglion

Answer 26

It integrates info from several brain regions in order to convey the needs of the organisms to preganglionic autonomic centers in brainstem and spinal cord. Also coordinates humoral respose via pituitary