B12 Homeostatis in Action Flashcards
What is hypothermia?
When the body’s average temperature is too LOW
What is hyperthermia?
When the average body temperature is too HIGH
What is the average human body temperature?
Around 37°C
What happens if the body temperature is too low?
Enzymes and substrates don’t have enough energy to collide so that the metabolic rate is really low.
What happens if the body temperature is too high?
Enzymes denature and metabolic reaction will stop.
How does the body control hypothermia?
- Shivering
- Hair on skin stands up (goosebumps)
- Vasoconstriction
How does shivering help the body warm up?
Vigourous muscle contractions release thermal energy by respirstion
How does hair on skin standing up help warm up the body?
It traps air to provide a layer of insulation.
- air is a good insulator
What is vasoconstriction?
Blood vessels (that supply blood to the skin) constrict so that blood dosen’t flow closer to the skin.
How does vasoconstriction help warm up the body?
It reduces the amount of heat lost by radiation
How does the body control hyperthermia?
- Vasodialation
- Hair on skin stays flat
- Body starts to sweat
What is vasodialation?
Blood vessels (which supply blood to the skin) dialets so that blood flows closer to the skin.
How does vasodialtion help cool down the body?
It increases the amount of heat loss by radiation.
How does flat hair on the skin help cool down the body?
Air level above the skin is thinner for less insulation.
How does sweating help cool down the body?
Respiration releases heat energy. Evaporation of water in sweat absorbs heat energy from the body.
What controls the body’s temperature?
The thermoregulatory centre in the hypothalamus.
What is the function of the renal artery?
It carries oxygenated blood to the kidneys
What is the function of the renal vein?
It carries deoxygenated blood away from kidneys.
What are the kidneys?
The place where blood is filtered and where urine is produced.
What is the function of the ureters?
They are small tubes which transport urine from kidneys to the bladder.
What is the function of the bladder?
To store urine temporarily.
What is the function of the urethra?
To release urine from the bladder.
What control the opening and closing of the urethra?
Rings of circular muscles.
Protiens are digested into….
amino acids by protease in the stomach.
Like glucose, can excess amino acids be stored.
No
What happens to excess amino acids?
They are broken down in the liver to make urea (a metabolic watse product)
What are the kindeys made up of?
Large number of small units called Nephrons.
What are the three stages of urine production?
1) Ultra-Filtration
2) Selective Reabsorbtion
3) Excretion of Urine
What happens during ultra-filtration?
Blood travels through the glomerulus at a high pressure so small molecules in the blood plasma are filtered into the bowman’s capsule
(the molecules are small enough to travel through the tiny gaps into blood cappilaries)
What are some small molecules in the blood plasma that are filterd out?
- Vitamins
- Water
- Amino Acids
- Urea
- Glucose
- Salt
What is selective reabsorbtion?
When the filtrate travels through the nephron some useful substances are reabsorbed into the blood.
What are useful substances that are reabsorbed and how much of it are reabsorbed?
- Glucose (all)
- Amino acids (all)
- Vitamins (some)
- Water (some)
- Salt (some)
Why is none of the urea reabsorbed?
Because it is a waster product.
What happens at the excretion of urine?
When the filtrate travels into the collecting duct it has a high concentration of urea, some water, some salt and some vitamins. This is now called urine and is excreted into urethra.
What happens during a dialysis?
Patients blood is pumped out and it’s passed through a tube of partially permable membrane, which is placed in a dialysis fluid. This fluid has the same composition as patients blood plasma but dosen’t contain any urea, which means urea diffuses out from patients blood into dialysis fluid.
What are the advantages of a dialysis?
- Clear blood
- No risk of surgery
What are the disadvantages of a dialysis?
- Diet of protien must be controlled
- Long term expense
- Dependant
- Infectious and blood clotting risks
- Not a permenant cure
What is a kidney transplant?
A healthy kidney from a matching donar is used to replace the kidney which is not functioning.
What are the advantages of a kidney transplant?
- Permanant Treatment
- One time cost
- Independant
What are the disadvantages of a kidney transplant?
- Hard to find
- Surgey Required
- Risk of immune rejection means immuno-suppressed drugs are taken making patient susceptible for infections
What is immune-rejection?
If cell surface recpetors of patiens white-blood cells and donar’s cells don’t match then patients cells start to produce anti-bodies to destroy the kidney.
What happens when water level in the blood is too low?
1) Osmoregulatory centre (in the hypothalamus) detects the low water level in blood
2) It send signals to secrete more ADH in the blood
3) More ADH is transported to the kindeys
4) Walls of the collecting duct become more permeable to water
5) More water is reabsorbed into the blood and less water is released in urine
What happens when the water level in the blood is too high?
1) Osmoregulatory centre (in the hypothalamus) detects the high water level in blood
2) It send signals to secrete less ADH in the blood
3) Less ADH is transported to the kindeys
4) Walls of the collecting duct become less permeable to water
5) Less water is reabsorbed into the blood and more water is released in urine
What are the main waster products of the body?
- Excess water
- Urea
- Excess ions
- Carbon Dioxide
Why are amino acids converted into urea?
Excess amino acids are deamimated in the liver to form ammonia which is toxic, so it’s immediatelt converted to urea.
What is nitrogen balance?
The control of excess amino acids in the blood
