Physiology - HOMEOSTASIS Flashcards
What is homeostasis ?
2
physiological process by which the internal systems of the body (temp, pressure, pH) are maintained at at equilibrium ,despite variations in the external conditions .
or
simply :
maintenance of a relatively constant or stable internal environment .
what are the main concepts required for homeostatic control system ?
2 classes ?
examples ?
(6)
1) Intrinsic control system = local control ( within an organ)- paracrine and autocrines ie : Hypoxic (low oxygen level within tissue) ——–>vasodilation of blood vessels
2)Extrinsic control system = reflex control ( long distance control via nervous, endocrine systems )
ie: Blood pressure
1-receptors to pick up the change in internal environment = uses negative feed back ( baroreceptors fro BP )
2-Control centre = evaluates the change by comparing it to the set point -hypothalamus/ medulla oblongata in brain for baroreceptors
3-Effectors - return the conditions to normal (skin, blood vessels, sweat glands, arrector pilli muscles, skeletal muscle ,endocrine glands )
describe thermoregulatory homeostatic control
3
1- receptors -peripheral and central thermal receptors
2-control centre = hypothalamus
3- effectors = blood vessels in skin , sweat glands, arrector pili muscles , skeletal muscles , endocrine organs
what limits homeostasis(3)
- extremes of age
- Disease
- Homestostatic imbalance
how does disease arise from failure on homeostasis ?
3
the homeostatic imbalance !
ie : in cardiovascular system this leads to
-atherosclerosis (build up to LDL in arteries )
-chronic hypertension
-Congestive heart failure
in the endocrine system :
-type 1 diabetes ( no insulin)
what are the internal factors which are monitored by homeostasis ?
(7)
1-temperature 2-concentration of salts, water, electrolytes 3-nutrients 4-pH 5-concentration of O2 and CO2 6-concentration of waste products 7-volume and temperature
