Skin Physiology - Trachte Flashcards
Remember - Dr. Trachte claims to be a lot more interested in all of us understanding how things work rather than memorizing small facts. Test questions are likely to involve understanding big concepts.
Why do people’s faces get very red during overexertion??
Large blood flow is sent to the surface of the skin in order to cool the body
When heat needs to be retained, arterioles can actually shunt blood directly into arterioles rather than the skin. Heat conserved this way.
Mark Johnson is probably a pro at this because he is an intense cross-country skier.
Where do sympathetic nerves synapse before then innervating their target organ?
The paravertebral ganglion on either side of the spinal cord
What neurotransmitter is released by the sympathetic preganglionic nerves?
What receptor does this neurotransmitter activate?
Acetylcholine
Activates nicotinic receptors
Why does smoking increase your heart rate?
Nicotine in tobacco acts on nicotinic receptors which stimulate the sympathetic nervous system
What neurotransmitter is generally released by the sympathetic postganglionic nerves?
What is the exception?
Noreprinephrine
The exception are the postganglionic nerves that innervate the skin. They actually use acetylcholine.
Acetylcholine can then be used to DILATE blood vessels in the skin by using guanylyl cyclase and NO. Also cause sweating.
This is odd because normally noreprinephine is used to constrict arterioles
What are the two types of sweat glands actually used for?
Eccrine - used for temp. regulation
Apocrine - caused by stressful situations - not active until puberty, foul smelling, pheremones?
How are sweat glands controlled?
Hypothalamus temperature sensors stimulate sympathetic nervous system - postganglionic ACh release activates eccrine sweat glands.
Apocrine sweat glands activated by noreprinephrine
Explain simply how the secretory and reabsorptive coils work in a sweat gland:
In the secretory coil: NKCC cotransports Na, K, and 2 Cl into the cell. CFTR and CLCA transport the Cl into the sweat gland’s lumen.
In the reaborptive coil: CFTR brings Cl back into the endothelial cell
The sweat goes out the pore hypotonic!
Cystic fibrosis, CFTR not working so well and the sweat is very salty
What kinds of drugs suppress sweating, and how?
Atropine - blocks muscarinic receptors
Antiperspirants - plug glands with metal salts
Furosemide (lasix) - blocks NKCC pump
Botulinum toxin - prevents ACh release from nerves
Beta-blockers - block hypoglycemic sweating (dont use this for diabetics…)
