Homeostasis + Kidneys

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  • Created by: Ruhab21
  • Created on: 16-10-20 18:03
Define homeostasis
The maintenance of a constant internal environment within a living organism, irrespective of the external conditions
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What is the main purpose of homeostasis?
To allow efficient function of the cells and enzymes by maintaining constant conditions
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Why might a short stout swimmer retain heat better than a tall thin one?
They have a smaller SA:vol ratio so there is less heat loss and more insulation
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What is the function of the kidney?
1) Osmoregulation
2) Removal of nitrogenous waste
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What is the function of the pelvis?
Acts as a funnel for the urine flowing to the ureter
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What structure brings blood to the nephron?
Afferent arteriole
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Where are amino acids deaminated and how?
Mammalian liver
1) Amine group is removed
2) Amine group is converted to toxic ammonia
3) CO2 is added to make urea which is less toxic, and this is transported to the kidney
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What is ultrafiltration?
Filtration under high pressure that seperates small soluble molecules from the blood plasma.
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What molecules are filtered from the blood in the kidney and what structure does this?
Glomerulus
Water, glucose, urea, salts
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How is high hydrostatic pressure generated in the glomerulus?
The afferent arteriole has a wider diameter than the efferent arteriole and therefore there is a build up of pressure
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What is selective reabsorption?
The process by which useful products such as glucose and salts are reabsorbed back into the blood as the filtrate flows along the nephron
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At what point is glomerular filtrate isotonic with blood plasma?
At the end of the proximal convoluted tubule
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What types of products are selectively reabsorbed in the nephron and how?
All the glucose and amino acids: co-transport and secondary active transport
Most of the mineral ions: Active transport
Most of the water: osmosis
Some urea: diffusion
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How is the proximal convoluted tubule adapted for selective reabsorption?
Numerous mitochondria for the ATP needed in active transport
Tight junctions so reabsorbed materials cant seep back into the filtrate
Large surface area with folded basement membrane
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Where are the channel and carrier proteins needed for selective reabsorption found in the PCT?
villi and basement membrane
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What is the function of the loop of Henle?
It concentrates salts in the tissue fluid of the medulla causing the osmotic flow of water out. This concentrates urine and makes it hypertonic to the blood.
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Describe process of Loop of Henle
Na+ and Cl- are actively pumped out of the filtrate in the ascending limb and into the medulla, lowering the water potential. This makes the water leave by osmosis into the vasa recta
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What is the name for the mechanism of concentrating urine in the Loop of henle and why?
1)Hairpin counter current multiplier
2) The medulla becomes more salty as the loop continues and the limbs have opposite directions and changes in concentration.
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Explain how ADH increases the permeability of the collecting duct.
In the presence of ADH, cells of the distal convoluted tubule and the collecting duct incorporate aquaporins into their cell membranes to allow passage of water out and into the vasa recta.
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What is the name of the receptors that detect changes in water levels of the blood nd where are they found?
Osmoreceptors in the hypothalamus
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How does high blood pressure damage the kidney?
It damages the structure of epithelual cells and basement membrane of the glomerulus by forcing the proteins out, affecting ultrafiltration
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Why might diabetes cause the kidneys to fail?
The high glucose conc in the plasma results in the glomeruli losing protein into the filtrate triggering scarring.
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What type of nitrogenous waste do aquatic animals produce and why?
Highly toxic ammonia is released directly since its very soluble in water and can diffuse to a non toxic level
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Why do mammals produce urea instead of other forms of nitrogenous waste?
Its less toxic than ammonia so the body tissues can tolerate it in high concentrations for short periods of time
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What type of nitrogenous waste do birds, reptiles and insects produce and why?
Non toxic uric acid is produced because its insoluble in water and therefore doesnt require much. These animals can survive in dry environments
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Why might animals that live in deserts have longer loops of henle?
They require more time to make the medulla saltier whixh results in a lower water potential and a greater osmotic gradient so morw water is reabsorbed
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If the kidney fails completely, what treatment is taken?
The transplant with one single healthy donor kidney since its sufficient to balance the blood
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In what case might a kidney donor be rejected and how can this be fixed?
1)Due to different blood types.
2) Antigens on the donor kidney differ from antigens on the cells of the recipient so their immune system attacks.
3) Immunosuppressant medicines must be taken all their lives
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Name the two types of dialysis
Haemodialysis
CAPD: continous ambulatory peritoneal dialysis
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Why do potassium levels need to be controlled in the blood? What are they controlled by?
High blood K could lead to heart arrhythmia.
Its treated with glucose and insulin
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Why is an anticoagulant used at the start of haemodialysis machine but not at the end?
To prevent the clotting of blood as it goes through the machine. It cant be used at the end as the blood needs to clot in the body as it returns in case of cuts
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Other cards in this set

Card 2

Front

What is the main purpose of homeostasis?

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To allow efficient function of the cells and enzymes by maintaining constant conditions

Card 3

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Why might a short stout swimmer retain heat better than a tall thin one?

Back

Preview of the front of card 3

Card 4

Front

What is the function of the kidney?

Back

Preview of the front of card 4

Card 5

Front

What is the function of the pelvis?

Back

Preview of the front of card 5
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