Homeostasis In Action Flashcards
What does the control of our body temperature rely on
Thermoregulatory centre in the hypothalamus
What does the thermoregulatory centre contain
Receptors that are sensitive to temperature changes in the blood
How does your body cool you down?
Vasodilation = blood vessels dilate allowing more blood to flow, skin flushes transferring more energy to the surroundings Sweat = sweat glands in skin sweat, water evaporates from skin, transferring energy to the surroundings
How does your body keep you warm?
Vasoconstriction = blood vessels constrict, reduce blood flow, reduce energy transferred to surroundings
Sweat production stops = less water from sweat evaporates, less energy transferred
Shiver = skeletal muscles contract and relax quickly, exothermic process, energy transferred raises body temperature
Removing CO2
Produced during respiration
Dissolved CO2 is acidic = affect enzymes working
CO2 diffuses out of cells into blood down concentration gradient = diffuses from blood into our alveoli in lungs
Air containing excreted CO2 removed when exhales
Side effect = lost water when exhale
Removing Urea
Produced = eat too much protein and tissue worn out
Extra protein can’t be stored = broken down
Amino acids can’t be used as fuel so,
Liver removes amino group from amino acids by deamination = forming ammonia
Ammonia immediately converted into urea and excreted from body
Rest of amino acids used in respiration/to make molecules
What is controlled in your body in terms of water and mineral ions?
No control:
-Water leaves lungs when exhale
-Water, mineral ions and urea lost in skin in sweat
Control:
-Urea, excess water and excess mineral ions secreted in urine = maintains water and mineral content within narrow limits and removes urea
What happens if you drink too much water?
Homeostasis in water balance
Short of water = kidneys conserve it -> produce very little very concentrated ruin and water is saved
Drink too much = kidneys produce lots of dilute urine to get rid of excess
How are mineral ions lost in your body?
Sweat through skin
Excrete in urine
How do your kidneys work
Filter your blood
Blood cells and large proteins = too big to leave blood in filtering process and can’t go into kidney tissues
So glucose selectively reabsorbed back into the blood by diffusion and active transport
Amount of water reabsorbed controlled by feedback mechanism and kept within a narrow range
How do kidney tubules work and effect the body?
Kidney tubules selectively reabsorb water and mineral ions
Amount of water in blood = maintained by negative feedback with releasing ADH
What happens if solutes are concentrated?
Receptor cells in brain detect concentration of solutes in blood
Too concentrated = released lots of ADH
Tubules reabsorb more water
Urine = concentrated
What happens if solutes are dilute?
Less ADH is released into blood
Less water reabsorbed into tubules
Produce large volume of dilute urine and blood solute concentration is turned back to normal
What is dialysis
The function of the kidney is carried out artificially
What does a dialysis machine do?
Persons blood leaves their body and flows between partially permeable membrane
The other side of the membranes is the dialysis fluid with the same concentration of blood of a healthy person
Restores concentrations of dissolved substances to normal levels
Takes 8 hours
Have to manage diet to keep blood chemistry stable
What happens if your kidneys don’t work?
Concentrations of urea and minerals ions build up in blood
How does a dialysis machine work?
1) Blood removed from patient and flows into the dialyzer - kept separated from dialysis fluid by a partially permeable membrane
2) The dialysis fluid contains the same concentration of glucose and salts as normal blood plasma = no net movement of glucose out of the blood by diffusion
3) Excess salts diffuse into dialysis fluid
4) The dialysis fluid contains no urea, so all of the urea diffuses from the blood in to the dialysis fluid from the high concentration in the blood to the lower concentration in the dialysis fluid
5) The blood and dialysis fluid move in opposite directions across the membrane = maintains concentration gradients all the way along
6) The clean blood is returned to the patient and the waste dialysis fluid is disposed of.
What do you have to do if you have dialysis?
Controlled diet Long sessions with machine Feel tired and unwell Over many years gets more difficult to control Control protein intake Control salt intake
Rejection in kidney transplants?
Antibodies attack antigens = destruction of donated kidney
Match antigens with same tissue type
Drugs to suppress immune response for the rest of their lives
Immunosuppressant drugs
Prevents patients from dealing effectively with infectious diseases
Don’t last forever
Dialysis vs Transplant
Transplant \+ cheaper \+ lead relatively normal life - take immunosuppressant drugs - shortage of donors - don’t last forever - risk of rejection - operation risks
Dialysis \+ available to all kidney patients \+ no drugs - expensive - regular dialysis sessions - limit salt and protein intake
