Biology B3.P2 Flashcards
Nephron process
-Filtration: Blood is filtered in the glomerulus, and small molecules like glucose, urea, ions (salts), and water pass into the renal capsule (Bowman’s capsule).
-Selective Reabsorption: Happens In the proximal convoluted tubule where all of glucose, some ions are reabsorbed back into the blood, based on the body’s needs.
-Excretion: The remaining waste products are excreted into the urine and leave the body.
Osmoregulation
-Helps maintain the balance of water in the body, mainly through kidneys.
-This ensures that the body’s cells have the right amount of water and electrolytes for normal function.
Osmoregulation process
-As blood flows through the hypothalamus (in the brain), the osmoreceptors their monitor the water potential of blood. (If water potential is too low the osmoreceptors will lose water by osmosis and they will shrink.
-Which then stimulates neurosecretory cells in the hypothalamus to produce ADH made in the cell body of the neuron, where it then flows down the axon to the posterior pituitary gland.(where it is stored until needed).
-When the neurosecretory cells stimulated , they send action potential down the axon
ADH
(Antidiuretic hormone )
-ADH is made in the hypothalamus (monitor the salt concentration in the blood) of the brain and is stored and released by the pituitary gland.
-ADH travels through the blood to the nephrons in the kidneys, where it binds to receptors on the cells of the collecting ducts.
-This binding increases the number of aquaporins (water channels) in the cell membranes, allowing more water to be reabsorbed from the urine back into the bloodstream.
-As a result, the body conserves water, helping it stay hydrated when it is dehydrated.
ADH function overall
ADH is made in the hypothalamus and stored in the pituitary gland. Its job is to help the kidneys absorb more water to keep the body hydrated.”
-If there is not enough water, the pituitary gland releases more ADH in order for the kidneys to reabsorb more water back into bloodstream, reducing the amount of urine that is going to go out as body needs to store water.
If there is too much water in blood then, the pituitary gland releases less ADH in order for the kidneys to absorb less water increasing the amount of urine going out.
RAAS
Renin-Angiotensin-Aldosterone System
-RAAS helps regulate blood pressure and fluid balance.
-When blood pressure is low, the kidneys release renin, which converts a protein from the liver called angiotensinogen into angiotensin I.
-Angiotensin I is then converted into angiotensin II (By ACE enzyme), which then which causes blood vessels to constrict and increases blood pressure.
-Angiotensin II also sends signals the adrenal glands to release aldosterone, which helps the kidneys retain sodium and water, further raising blood pressure.”
Treatment for kidneys (Dialysis)
Filters the blood into a machine which removes waste and excess water from the blood.
Blood is collected from a vein in the arm and passes along a tube that is semi-permeable.
Advantages:
Helps reduce levels of urea in blood and water/ ion levels are restored (balanced)
Disadvantages:
Risk of infection and blood clot
Expensive
Not as effective as transplant
How dialysis work
1Arterial blood leaves the arm
- Blood thinner is added to
prevent clotting - Blood travels through dialysis
machine - Dialysis fluid in
- Dialysis fluid containing waste
products and urea removed - Clean blood out
- Blood travels through a bubble
trap - Clean blood returns to a vein in
the arm
Haemodialysis
Method of removing impurities by pumping the patient’s blood through a dialyser, the specialized filter of the artificial kidney machine (haemodialysis)
-A tube is attached to a needle in your arm.
-Blood passes along the tube and into an external machine that filters it, before it’s passed back into the arm along another tube.
Peritoneal dialysis
-Is the layer of tissue that lines the abdominal cavity.
-peritoneum contains thousands of tiny blood vessels, making it a useful filtering device.
Before treatment starts, a cut (incision) is made near your belly button and a thin tube called a catheter is inserted through the incision and into the space inside your abdomen (the peritoneal cavity). This is left in place permanently.
Fluid is pumped into the peritoneal cavity through the catheter. As blood passes through the blood vessels lining the peritoneal cavity, waste products and excess fluid are drawn out of the blood and into the dialysis fluid.
The used fluid is drained into a bag a few hours later and replaced with fresh fluid.
Difference between dialysis
Haemodialysis: Blood is removed from the body, filtered through a dialysis machine to clean it, and then returned to the body. This is usually done at a clinic or hospital several times a week.
Advantages:
More efficient than peritoneal dialysis at clearing blood of toxin.
Disadvantage: patient tied to a machine 3 times a week and machine expensive.
Peritoneal Dialysis: The blood is cleaned inside the body using the peritoneum (the lining of the abdomen) as a filter. A special fluid is put into the abdomen, absorbs waste, and is then drained out. This can often be done at home.
Advantages:
Patients can walk around, can carry out dialysis at home or work.
Disadvantages:
Fluid has to be replaced several times a day. HIGH RISK of infection
Key distinction: Haemodialysis uses an external machine, while peritoneal dialysis relies on the body’s internal natural filter.
pros and cons of kidney transplant
Advantages
* no need for regular hospital attendance (for renal dialysis)
* more able to live normal lifestyle/ not attached to a dialysis machine for 8 hours each visit
* eat a normal healthy diet
* (overall) more cost effective/ less expensive
* can have living donors/donation from relative/ people can donate one of their two kidneys
* prolongs life of recipient
* routine/straightforward surgery
* stem cells/growing organs
Disadvantages:
* availability/shortage of donors
* reference to opt in/opt out
* not an immediate form of treatment
* invasive and requires surgery
* risk of anaesthetic
* risk of infection (due to surgery)/need for wound care
* need for tissue matching
* risk of rejection
* transplant may fail
* need for immunosuppressant drugs * increased susceptibility to infections (due to immunosuppressants)
* ethical considerations
