Skin Physiology

Question 1

Skin functions

Answer 1

shield body from invasion, excessive fluid loss

cool/prevent heat loss

endocrine/exocrine

Question 2

_______ innervation represents major control process over both blood flow and sweat gland activation

Answer 2

Sympathetic

Question 3

Critical factor for cutaneous blood flow

Answer 3

presence of arterio-venous anastomoses (bypass cutaneous capillaries to avoid heat loss)

Question 4

Preganglionic sympathetic nerves release

Answer 4

acetylcholine

Question 5

acetylcholine activates postganglionic nerve by acting on ______ receptor

Answer 5

nicotinic

Question 6

postganglionic sympathetic nerve releases _________ to ______ blood vesseles, via ______ receptors

Answer 6

norepinephrine - constrict

alpha1 receptors (GPCR)

Question 7

In skin circulation, sympathetic nerves can also ________, via ________ to _______ receptors in response to _____

Answer 7

vasodilate

acetylcholine to Beta receptors

heat

***Vasodilation of blood vessels –> increased heat loss

Question 8

Cold causes ________ of cutaneous blood vessels and _______ heat retention

Answer 8

vasoconstriction

increased

Question 9

Pain upon coming in from cold

Answer 9

constriction to limit blood blow/heat loss –> open up, reperfusion = painful

Question 10

2 types sweat glands

Answer 10

eccrine and apocrine

Question 11

Eccrine sweat glands

Answer 11

temperature regulation

Ach

directly to skin

Question 12

Apocrine

Answer 12

Stress sweat

ARound hair follicle in certain areas

Not active until puberty, bacteria make them stink

Question 13

Control of sweat gland secretions (eccrine)

Answer 13

Hypothalamus –> sympathetic nervous system –> Ach from postganglionic nerves to eccrine sweat glands

Question 14

__________ activates ________ receptors of eccrine sweat glands to increase sweating

Answer 14

Acetylcholine –> muscarinic

Question 15

Control of Apocrine sweat glands

Answer 15

norepinephrine –> a1, b1 receptors

Question 16

Mechanism of Sweat Gland Secretion

Answer 16

NKCC - pumps Na, K, Cl into secretory cells (Na/K-ATPase provides energy)

ClCa antiporter and CFTR put Cl into lumen

Na and H2O follow by osmosis

Ions and water reabsorbed by CFTR and ENaC channels later in duct - water NOT reabsorbed

Question 17

Drugs that suppress sweating

Answer 17

Atropine (block muscarinic receptors)

Furosemide (Lasix) - diuretic blocks NKCC

Antiperspirants - metal salts plug glands

Botox - prevent Ach release from nerves to suppress sweating

Beta blockers - prevent sweating response to hypoglycemia (dangerous)

Question 18

Cold causes _______ nerves to ______ cut. blood vessles by releasing ________ and ________ via ______ receptors

Answer 18

sympathetic nerves - constrict - norepinephrine - vasoconstrict - a1

Question 19

Heat causes ______ nerves to ____ cut. blood vessels by releasing ___ which ______ via _______ receptors in endothelium

Answer 19

sympathetic nerves - dilate - acetylcholine - dilates - muscarinic