homeostatic mechanisms Flashcards
what is homeostasis
maintaining constant internal environment of the body
role of skin in overheating
1.vasodilation of the blood cells, more blood reaches the surface of the skin, increase heat lost by radiation
2.sweat gland secrete waste, which evaporates, which cools down the body
role of skin in overcooling
1.vasoconstriction of the blood cells, less blood reaches the surface of the skin, reduce heat loss by radiation
2.sweat glands stop sweat secretion
3.hair erects to trap air which acts like an insulator to reduce heat loss
4.muscle shiver, increasing respiration rate to release heat
what is excretion
removal of metabolic wastes, toxic and excess substances
what is ultrafiltration
a passive process where urea, water, salts, glucose and amino acids pass from blood into nephron due to the high blood pressure, forming a fluid called “glomerular filtrate”. (blood cells and plasma proteins don’t pass due to their large size)
what is selective reabsorption
1.active process where useful substances are reabsorbed and pass from nephron to blood.
2.all glucose, all amino acids, and some salts are reabsorbed at proximal convoluted tube by active transport
3.water is reabsorbed in the loop of henle by osmosis
osmoregulation
1.water loss in sweat increases plasma concentration
2.receptors in the hypothalamus detect increase in plasma concentration
3.hypothalamus sends impulses to the pituitary gland to release ADH
4.ADH increases permeability of the collecting duct, increasing permeability to water, so water is reabsorbed back to the blood
5.volume of urine decreases and becomes more concentrated
kidney failure treatment
kidney transplant
what is tissue typing
classify the patient’s tissues to find a match genetically similar
what is immune suppressive drugs
supress immune system until the kidney is accepted by the body, however they leave the patient more likely to catch infectious diseases
advantages of kidney transplant
1.long term solution
2.time saving
3.free lifestyle
disadvantages of kidney transplant
1.difficulty to find donor
2.risk of surgery
3.possibility of tissue rejection
4.immunosuppressive drugs
disadvantages of renal dialysis
1.time consuming
2.expensive
3.damage to arteries and veins