| What is homeostasis? | The maintainance of a constant internal environment in the body |
| What are the 3 main components of homeostasis? | Receptors-detect a stimulus(change in the environment)
Coordination centres-in brain, spinal cord, and pancreas-recieve info & instigate response
Effectors-muscles or glands create response. Glands release hormones restoring optimum condition |
| Describe the thermeoregulatory process. | Contained in hypothalamus which has heat sensitive receptors. Skin also has receptors and sends impulses back to thermeoregulatory centre |
| What happens when we are too cold and too hot? | Hot:
(1)Thermoreceptors detect stimulus-(2)Hypothalamus sends nerve impulses to skin(3)Increased sweat, vasodilation, hairs flat(4)decrease body temp
Cold
(1)Thermoreceptors detect stimulus-(2)Hypothalamus sends nerve impulses to skin(3)Shivering, vasoconstriction, hairs stand trap air(5)increase body temp |
| Compare vasodillation and vasoconstriction? | Vasodilation-Blood vessels near skin dialate shunt vessels narrow to push warm blood to skin
Vasodilation-Blood vessels near skin constrict shunt vessels dialate to decrease warm blood reaching skin increase blood at core |
| What is osmoregulation? | The control of water levels and mineral salts in the blood |
| What happens if water levels arent regualted? | Either
Too much water enters cell-turgid-burst-hypotonic
or
Too much water leaves cell-flaccid-shrivel-hypertonic |
| Give 3 ways water is lost from the body. | 1)Urine from kidneys-controlled
2)Sweat from skin-uncontrolled
3)Water vapour from lungs when exhale-uncontrolled |
| What is the function of the kidneys? | Remove excess water, salts, urea |
| How are excess amino acids excreted? | 1)deaminated in liver to form ammonia
2)ammonia is toxic so immediately converted to urea for safe extraction
3)urea goes from liver through blood stream to kidneys then excreted |
| What is a nephron? | A microscopic filtering unit found in the kidney made of a tubule |
| Describe the filtration in the kidneys. | Stage 1)renal artery carries oxygenated blood to kidney filtered at high pressure at the start of the nephrons which reabsorbs useful small molecules: glucose, salt ions and water aiding ultrafiltration big molecules like protien can't fit
Stage 2)Selective reabsorbtion of molecules which the body needs back into bloodstream as much: glucose, water and ions the body needs
Stage 3)molecules not selectively reabsorbed: urea, excess water & ion excreted |
| Which key areas in the brain control ADH levels | Hypothalamus-detects change in blood plasma
Pituatary gland-regulates release of ADH (anti-diuretic hormone) |
| What is the use of ADH what does it do? | When blood is too concentrated, more ADH released by pituatary gland and causes kidney tubles to be more permeable allowing more water to be absorbed into the blood during selective reabsorbtion more water lost as urine
When blood is too dilute, less ADH released by pituatary gland and causes kidney tubles to be less permeable allowing less water to be absorbed into the blood during selective reabsorbtion less water lost as urine |
| What is dialysis and how does it work? | Its a process that allows people with kidney faliure to get blood filtered
1)unfiltered blood high in urea taken from blood vessel in arm, mixed with anti-coagulant to prevent blood clotting and pumped into dyalisis machine.
2)In the machine the dialysis is seperated by a partially permeable membrane, blood flows opposite direction to dialysis fluid maintaing concentration gradient
3)Dialysis fluid contains similiar glucose to ensure no net movement of glucose, and similiar ion concentration as blood ensuring that the minerals diffuse if necessary to maintain the correct amount, the fluid has no urea so all urea is extraced by diffusion. |
| Advantages and disadvantages of dialysis. | Advantages:
1)Reduces urea levels of patient, no overall change in glucose level, correct ion balance
2)no immune repressant drugs needed
Disadvantages:
1)Expensive machinery
2)used 2-3 times a week 4-6 hour periods
3)Patients must moniter their diet, low salt intake
4)only temporary for as along as transplant needed otherwise they will die |
| Give 3 key points in kidney transplant. | 1)Kidney cells have antigens on surface unique to patient preventing organ rejection (antibodies produced to destroy the kidney).
2)Tissue typing-a kidney is given to patients who have similiar antigens to the donor
3)Immuno-suppressant drugs-taken by patients for the rest of their lives, this means immune response is reduced both against kidney and pathogens |
| Advantages and disadvantages | Advantages-
1)Patients dont need to moniter diet
2)cheaper for NHS overall
Disadvantages-
1)Only last 8-9 years
2)taking imune repressant drugs increases risk of infection
3)shortage for organ donors
4)any operation carries risk of complications |
