B12 Flashcards
What is homeostasis?
Maintenance and control of our internal environment
What is temperature controlled by?
Thermoregulatory centre in the hypothalamus
How does the thermorugulatory centre control temperature?
Receptors that are sensitive to temp changes in the blood flowing through the brain.
How to blood vessels cool the body down?
Skin capillaries widen(vasodilation) to bring more blood to skin.
Skin flushes and heat is lost by radiation and convection
How does sweating cool the body down?
Sweat glands produce sweat which is secreted on the surface of the skin.
When it evaporates it removes heat from the skin
What is sweat made up of?
Water
Salts
Urea
How to blood vessels keep you warm?
Skin capillaries narrow to bring less blood to skin
This reduces heat loss by radiation
How does shivering reduce heat loss?
Skeletal muscles contract and relax rapidly releasing heat due to respiration that happens
Name 4 waste products
Carbon dioxide
Water
Mineral ion’s
Urea
How is co2 removed from body?
1) CO2 diffuses out of respiring cells and into plasma
2) CO2 diffuses from plasma into alveoli
3) here it is exhaled by the respiratory system as a gas
How is urea removed from the body?
1) urea diffuses from liver cells to plasma of blood
2) it is filtered out of the blood by the kidneys
3) removed from body as urine
How are excess amino acids and protein removed?
1) converse into ammonia
2) converted from ammonia to urea 3) 3) 3) which can be safely removed by the body
Rest of amino acids converted to glucose then respired or stored
What are the functions of the kidneys(3)
1) Removal of urea from blood
2) Removal of excess water and mineral ions from blood
3) conservation of water and mineral ions if In short supply
How do the kidneys work (4)
1) all water,mineral ions,glucose and urea pass from the blood to the kidney
2) all glucose reabsorbed by diffusion and active transport
3) no urea reabsorbed
4) water and mineral ions are selectively reabsorbed
What does ADH do?
Controls the amount of water reabsorbed from the kidney by making structures more permeable to water
Explain the role of ADH when water balance is low? (5)
1) detected by receptors in hypothalamus
2) causes pituitary to secrete ADH
3) ADH travels to kidney via blood
4) ADH makes collecting ducts in the kidney permeable to water which increases rate of reabsorption
5) this produces a small volume of concentrated urine
Explain the role of ADH when water balance is too high
1) detected by receptors in hypothalamus
2) causes pituitary to secrete less ADH
3) with less ADH less collecting ducts are permeable to water which decreases the rate of reabsorption back into blood
4) produces large volume of diluted urine
2 effects of kidney damage
Build up of toxins
Cells damaged due to osmosis
What is dialysis?
When a machine carries out the function of the kidney
All blood is passed through machine to get it cleaned
How does dialysis work?
Blood flows between partially permeable membranes in the machine
On the other side of machine is dialysis fluid
Substances diffuse form blood to fluid and vice versa until concentrations are balanced
How does an organ become rejected?
1) immune system recognises it as foreign and attacks it
2) antigens of cell surface membranes are not recognised by immune system
3) lymphocytes produce antibodies complimentary to antigens
4) antibodies bind and kidney cells are destroyed
How does tissue matching reduce rejection?
Find a kidney with similar antigens to recipient
How do immunosuppressant drugs reduce rejection?
They suppress the immune system and turn down its response.
Disadvantage of immunosuppressants
They prevent patients from being able to deal with other infections
