B12 - Homeostasis in action Flashcards
What happens when core temperature is too hot
Dilation of the blood vessels supplying the skin capillaries (vasodilation) causes increased blood flow to the skin, increasing heat transfer to the environment. The sweat glands also produce more sweat, which transfers energy from the body to the environment as it evaporates.
How is body temperature monitored
Receptors in the thermoregulatory centre detect the temperature of the blood in the brain, and that the thermoregulatory centre receives information about skin temperature from receptors in the skin, sent via nervous impulses
What haooens when core temperature is too cold
The sweat glands stop producing sweat, and the blood vessels supplying the skin capillaries constrict (vasoconstriction), causing decreased blood flow to the skin, which decreases the transfer of energy to the environment. The muscles cause the body to shiver - this requires respiration, so some energy is transferred to the body.
What happens to excess amino acids
Enzymes in liver split amino acids into glycogen and ammonia (deamination)
Ammonia is toxic so it is made into urea which is excreted via kidneys
Function of kidneys
Remove:
Excess water, excess mineral ions and urea from blood
How do kidneys work
1 - filtration
Blood filtered out of capillaries. Blood cells + large molecules too big to pass so they stay. Move to kidney tubule.
2- Selective reabsorbtion
Reabsorb all glucose, some water, some ions (depending on blood conc. for water + ions)
3- Form urine
Molecules not reabsorbed (urea + excess) continue along tubule as uring. Pass down to ureter to urethra.
How are water and ions lost
Exhalation + sweat
ADH
Released by PT when blood water conc. is too low. Kidney tubules more permeable. Stimulates kidneys to absorb more water. Less water lost in urine (dark)
When is blood too concentrated/ dilute
Conc. = too little water
Dilute = too much water
Kidney failure initial treatment
Diet monitoring. Less protein. Less salt. Monitor water intake.
Significant kidney failure treatment
Dialysis/transplant.
1. Unfiltered blood taken from artery in arm
2. Anticoagulant added
3. Dialysing fluid separated from blood by partially permeable membrane.
4. Osmosis and diffusion happens so urea diffuses out
5. Blood psasses through bubble trap + filter then taken back into vein.
Transplant - take renal vein, artery + ureter out.
Transplant +/-
+
Long term
Most freedom
Less restrictive diets
Free
-
Different antigens - immune response
Permanently on immunosuppresants
Needs donor
Dialysis +/-
+
No surgery
Keeps you alive
-
Damage blood vessels
Very time consuming
Not permanent
Expensive
Invasive
Infection risk
