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BiologyF2144 > Kidneys > Flashcards

Kidneys Flashcards

1
Q

What supplies blood to kidneys?

A

Renal artery and drained by renal vein

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2
Q

What is the role of the kidney?

A

Remove waste products from blood and produce urine

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3
Q

What are the regions of the kidney?

A

Cortex, medulla and ureter

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4
Q

What is a nephron?

A

Functional unit of kidney, microscopic tube that receives fluid from blood capillaries and converts this to urine, which drains into ureter

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5
Q

What is the glomerulus?

A

Fine network of capillaries that increases the local blood pressure via affecting and efferent arterioles to squeeze fluid out of the blood, surrounded by cup shaped now end capsule which collects the fluid and leads into the nephron

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6
Q

What are the four parts of the nephron?

A

Proximal convuluted tubule, loop of henle, distal convoluted tubule and collecting duct
Start in cortex, with glomerulus and bowmans capsule, fluid pushed into capsule by ultrafiltration

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7
Q

What is selective reabsorption?

A

Useful substances are reabsorbed from the nephron j to blood steam while other excretory substances remain in the nephron

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8
Q

How does composition of fluid in nephron change?

A

All sugars, salts and most salts and some water reabsorbed, 85% reabsorbed, in descending limb, water potential decreased by addition of salt and removal of water, in ascending limb, water potential is increases as salts are removed by active transport. In collecting duct, water potential increased again by removal of water, ensures urine has high concentration of dilutes, and low water potential

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9
Q

Why are there many capillaries around the nephron?

A

So materials reabsorbed from fluid in tubule, can re-enter the blood

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10
Q

How is blood pressure altered in the glomerulus?

A

Blood flows in through afferent arterioles, wider than efferent arterioles, which increases pressure, pressure lower in bowmans capsule, so fluid pushed out if capillaries in glomerulus

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11
Q

What are the three layers of the bowmans capsule?

A

Endothelium of capillaries, narrow gaps between cells that plasma and dissolved substances can pass through
Basement membrane of fine mesh of collagen fibres and glycoproteins, filter to prevent molecules larger than 69 000 passing through
Epithelial cells of bowmans capsule, posi urea, finger like projections, major processes that ensure there are gaps between the cells

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12
Q

What is filtered out of the blood?

A

Water, amino acids, glucose, urea, inorganic ions

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13
Q

What remains in capillary after ultrafiltration?

A

Blood cells and proteins, proteins mean low water potential so some fluid is retained in blood, need low water potential to allow reabsorption of water at a later stage

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14
Q

Why may protein in urine be sign of hypertension?

A

Proteins supposed to remain in capillaries, cannot fit through basement membrane, so proteins in urine indicate high blood pressure that has caused damage to capillaries of glomerulus and epithelium of bowmans capsule

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15
Q

How are cells in the nephron specialised for selective reabsorption?

A

Most occurs in PCT, all glucose and amino acids, and some salts with water. Cells of PCT specialised to a give reabsorption
Plasma membrane in tubule highly folded to form micro villi
Also has cotransporter proteins that transport glucose in association with sodium ions-facilitated diffusion
Opposite membrane of cell folded, Na/k pumps
Cell cytoplasm has many mitochondria

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16
Q

How does reabsorption occur?

A

Na/K removed sodium from cells, reduces concentration inside cell, so sodium transported into cell from tubule fluid along with glucose or amino acids, glucose concentrations rise in cell, diffuse out of cell into tissue fluid. May be enhanced by active removal, substances diffuse from tissue fluid to blood, reduces water potential in cells, increases potential in tubule fluid, so water enters cells and then blood by osmosis. Larger molecules may be reabsorbed by endocytisis

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17
Q

What is the role of the loop of henle?

A

Create a very low (negative) water potential in the tissue if the medulla, ensures even more water can be reabsorbed from fluid in collecting duct

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18
Q

What is the loop of henle?

A

Descending limb into medulla and ascending limb back into cortex, arranged to allow salts to be transferred from ascending limb to descending limb, increase concentration if salts in tubule fluid, so they diffuse out if ascending limb into surrounding medulla tissue creating very low water potential

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19
Q

How is water reabsorption achieved?

A

Fluid becomes more negative as it descends into medulla , water loss to tissue fluid and diffusion of ions into tubule from surrounding tissue fluid , as it ascends, water potential becomes higher, as at base of tubule, sodium and chloride diffuse out of tubule into tissue fluid, higher up, ions actively transported out, wall of ascending limb impermeable so water can’t diffuse out, so fluid loses salts but not water

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20
Q

What is a hairpin countercurrent multiplier?

A

Arrangement if tubule in sharp hairpin so that one part passes closer to other part with fluid flowing in opposite direction, allows exchange between contents, can be used to create high conc of solutes

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21
Q

What happens to water potential of tissue fluid in medulla?

A

Movement of salts from a sending limb into medulla creates very negative water potential concentration in tissue fluid, increasingly negative deeper into the medulla

22
Q

What is the urine like at top of ascending limb?

A

Very dilute as ions actively transported out, water may then be reabsorbed from urine in distal tubules and collecting ducts, amount of water reabsorbed depends on needs of body

23
Q

Why is it beneficial to mammals living in arid regions to have higher salt concentrations in their medulla?

A

Greater water potential gradient can be achieve between urine in collecting duct and medulla, so more water reabsoberd, urine more concentrated

24
Q

What happens at the DCT?

A

Active transport adjusts concentrations of various salts, from here fluid flows into collecting duct

25
Q

What happens at the collecting duct?

A

Carries water back down through medulla to pelvis, medulla has very low water potential, high in fluid, so waged moved out of collecting duct by osmosis, enters blood capillaries by osmosis and carried away.

26
Q

Tissue fluid inMedulla has low water potential, so how does water pass from tissue fluid to blood plasma by osmosis?

A

Blood vessels in medulla looked, so allows exchange if solutes between ascending vessel and descending vessel, blood vessels arranged to create plasma with even lower water potential than the blood

27
Q

What is osmoregulation?

A

The control and regulation of water potential of the blood and body fluids, in humans the kidney controls the water potential of the blood

28
Q

Where is water gained from?

A

Food, drink and metabolism

29
Q

Where is water lost from?

A

Urine, sweat, exhaled air, faeces

30
Q

How is water reabsorption controlled?

A

Amount of water reabsorbed is altered by altering permeability of walls of collecting duct to water

31
Q

What are antidiuretic hormones?

A

ADH is released from pituitary glands and acts on collecting ducts in kidneys to increase their reabsorption of water

32
Q

How is permeability of cells of collecting duct altered?

A

Membrane bound receptors for ADH, cell binds, activates adenyl cyclase, which generates cAMP, enzyme controlled reactions to insert vesicles containing aquaporins into plasma membrane, the more ADH in the blood, the higher the permeability of the collecting duct, therefore more water is reabsorbed. Less ADH and membrane folds in to create new vesicles that remove aquaporins from membrane, so less permeable, less reabsorption

33
Q

What are osmoreceptors?

A

Receptor cells that monitor the water potential of the blood, if it has a low water potential, then water is moved out by osmosis, causing them to shrink, which causes stimulation of neurosecretory cells.

34
Q

Where are osmorecptors found

A

Hypothalamus, part of brain that contains neurosecretory cells and various rectors that monitor the blood

35
Q

What are neurosecretory cells?

A

Specialised cells that act like nerve cells but release hormone into the blood. ADH is manufactured in cell body and passes down axon to be stored in terminal bulb, if action potential passes down the axon then ADH is released from the terminal bulb

36
Q

How is ADH concentration in the blood adjusted?

A

Monitored by osmoreceptors, respond to effects of osmosis, water moves out if water potential liw, so shrink, which stimulate neurosecretory cells, specialised neurones that produce and release ADH, manufacture in cell body which is in hypothalamus, flows down axon to terminal gland in posterior pituitary gland, when stimulated, send action potential and hormone related, enters blood capillaries, targets collecting duct, when water potential rises, less released and ADH broken down

37
Q

By does too much alcohol cause dehydration?

A

Inhibits production of ADH, so collecting duct less permeable to water, much less is reabsorbed, so higher water loss

38
Q

What are diuretic drugs?

A

Increase urine production, less permeable, less reabsorbtion, relieve water retention

39
Q

What are antidiuretic drugs?

A

Increase reabsorption of water, relieve diabetes insipidus

40
Q

What are the common reasons if kidney failure?

A

Diabetes mellitus

Hypertension, infection

41
Q

Why is kidney failure bad

A

Unable to remove excess water and certain waste products, unable to regulate concentrations, rapidly leads to death

42
Q

What is dialysis?

A

Use if a partially permeable membrane to filter the blood, works by passing blood over dialysis membrane, which is partially permeable and allows exchange of substances between blood and dialysis fluid, which contains correct concentration of substances, any substances in excess in blood diffuse across membrane into dialysis fluid. Substances too low in concentration dissolve into blood. Combined with carefully monitored diet

43
Q

When is haemodialysis?

A

Blood from vein passes into machine containing dialysis fluid, heparin added to avoid clotting, bubbles removed, performed at clinic three times a week, several hours a session

44
Q

What is peritoneal dialysis?

A

Filter is body’s abdominal membrane, peritoneum, tube implanted in abdomen, dialysis solution poured in a s fills space between abdominal walls and organs, then drained after several hours, usually perches at home, several sessions a day. Patient can be mobile, ambulatory

45
Q

What are the advantages of kidney transplant?

A 
Freedom from dialysis
Diet less limited
Feel better physically
Better quality of life 
No longer chronically ill
46
Q

What are the disadvantages of kidney transplant?

A 
Need immunosuppressants, more at risk of illness 
Major surgery 
Risk of infection 
Frequent check ups 
Side effects
47
Q

How can urine be tested for pregnancy?

A

Embryo secretes hCG hormone, small so found in urine. Pre baby tests made with monoclonal antibodies, antibody is specific, binds to hCG, any hCG in urine attaches to antibody that is tagged with a blue bead, moves up strip until sticks to band of immobilised antibodies m, held in place, forming blue line, always a control line, 2 lines indicate pregnancy

48
Q

What are monoclonal antibodies?

A

Identical because they have been produced by cells that are clones if one original cell

49
Q

How can irons be used to test for anabolic steroids?

A

Anabolic steroids increase protein synthesis in cells, build up if cell tissue in muscles, give advantage in competitive sport so banned, have half life of 16 hours so in blood for days, relatively small so pass into nephron, urine analyses in lab by gas chromatography or mass spectroscopy, to produce chromatography, compared to samples of drugs

50
Q

Why does haemodialysis fluid need to be kept at 37 degrees at sterile?

A

Sterile so didn’t cause infection in recipient, good medium for microorganisms, kept at body temperature do doesn’t cause hypo/hyperthermia helper in added to prevent coagulation

BiologyF2144 (11 decks)

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