Skin Physiology Flashcards
What regulates heat loss or conservation?
Regulation of cutaneous blood flow by anastomoses. If cold, arterioles bypass the capillaries and go directly to venules to maintain heat. If not, arterioles send blood to the capillaries near skin surface for heat loss.
What neurological system regulates cutaneous blood flow? How many nerves are involved?
The sympathetic nervous system, efferent nerves leaving the spinal cord with a synapse OUTSIDE of the CNS (usually paravertebral ganglia). Two nerves are involved, the pre-ganglionic is short and the post-ganglionic is long.
What neurotransmitter/receptor is used at the synapse of a pre to post-ganglionic nerve? What chemical activates the receptors for depolarization?
The preganglionic nerve releases acetylcholine which activates the post-ganglionic nerve via nicotinic receptors. Sodium activates nicotinic receptors.
Once activated, postganglionic nerves release WHAT which does WHAT to blood vessels?
Releases norepinephrine which acts on G protein coupled receptors to constricts blood vessels.
What sympathetic neurotransmitter acts to vasoDILATE?
Acetylcholine acting on a G couple protein receptor
Effect of heat and cold on cutaneous blood vessels?
Heat DILATES for increased heat loss from capillaries at skin surface
Cold CONSTRICTS for decreased heat loss, instead directs blood just to vessels by anastomoses. May cause pain when re-perfusing!
Is it easier for the body to generate heat or lose it (sweat vs shiver?)
Easier to generate it by a shiver
What are the 2 types of sweat glands? What neurotransmitters act on them?
Eccrine (body temp regulation- act by ACh) and apocrine (nerves- act by norepinephrine)
Which sweat gland is not activated until puberty?
Apocrine- nerves result in foul smelling sweat
How many nerves are involved in sympathetic stimulation of sweat glands? What are their neurotransmitters and receptors?
- Pre-ganglionic cell releases ACh which acts on nicotinic receptors of post-ganglionic cell. Post ganglionic cell releases ACh which acts on cell of sweat gland via muscarnic receptors –> sweating for body temp regulation
What part of the brain controls neurotransmitters for sweat gland regulation? How does it work?
The hypothalamus because it contains transient receptor potentials that act as sensors for change in temperature —> ACh release to activate eccrine sweat glands
What transporter is involved in sweat gland secretion?
NKCC- Na, K and 2 Cl pump
Describe the mechanism of the sweat gland?
Cells secrete ions into the lumen (NKCC pump, CFTR etc), water follows by aquaporins, ions are reabsorbed from the lumen by the CFTR and ENaC channels. Results in dilute solutions of ions in sweat!
How does CF relate to sweat glands?
Cannot reabsorb Cl by the CFTR transporter leading to excess salt in the sweat, this may act in diagnosis of CF.
What drugs regulate sweating? Are they safe?
Many drugs suppress sweating by various mechanisms (Atropine blocks muscarinic receptor, Furosemide blocks NKCC pump, antipersperants are metal salts that plug glands, botulinum toxin prevents ACh release, and beta blockers block sweat in response to hypoglycemia) but they are NOT SAFE because the body then cannot regulate temperature!
