5.1.2 The Kidney

Question 1

Where is the kidney found

What is jt surrounded by

Answer 1

Attached to the back of the abdominal cavity

A layer of fat and fibrous connective tissue

Question 2

What two processes is the kidney involved in

Answer 2

Excretion and osmoregulation

Question 3

Explain the difference between the cortex and the medulla

Answer 3

Cortex= dark outer layer, dense capillary network and blood filtering takes place here

Medulla= lighter in colour contains the nephrons and collecting ducts

Question 4

How many nephrons in each kidney

Answer 4

1 million

Question 5

What is the glomerulus

Answer 5

A fine network of capillaries which increases blood pressure to push fluid out

Question 6

What is selective reabsorption

Answer 6

When useful substances are reabsorbed back into the blood and excretory products remain in nephron

Question 7

Where does ultrafiltration take place

Answer 7

In the bowmans capsule

Question 8

How is tissue fluid formed

Answer 8

High hyrdrostatic pressure forces fluid out of the capillary into the tissue

Moves back into the blood when low hydrostatic pressure is formed at the venous end of the capillary

Question 9

Describe the process of ultrafiltration at the glomerulus

Answer 9

Blood enters afferent arteriole (large diameter) under high pressure

The efferent arteriole has a smaller diameter, this increases bloods hydrostatic pressure in glomerulus

Hydrostatic pressure In glomerulus bigger than bowmans capsule, Fluid is forced out into bowmans capsule

Basement membrane: stops erythrocytes and large molecules from passing through
Fenestrations: in squamous endothelial cells of capillary allow small substances through (not RBC)
Podocyte cells: extensions called pedicels prevent large plasma proteins and platelets from passing through

Question 10

How are podocytes adapted

Answer 10

Have extensions called pedicels (aka major processes) have gaps to allow specific molecules through

Question 11

How does high blood pressure damage capillaries

Answer 11

Allows proteins and sometimes RBC to enter the filtrate

Question 12

how is ultrafiltration similar and different to tissue fluid formation

Answer 12

similarities- both occur in the capillary, large molecules remain in the capillary, molecules are reabsorbed

differences- filtrate enters PCT, filtrate bathes tissues and cells
molecules that are not reabsorbed form urine, molecules that are not reabsorbed form lymph

Question 13

why must glucose be reabsorbed back into the blood

Answer 13

to be used in aerobic respiration

Question 14

where and what is reabsorbed

Answer 14

in the PCT

glucose, amino acids, vitamins and hormones

Question 15

what percentage of fluid is reabsorbed

Answer 15

85%

Question 16

what type of cells make the PCT

Answer 16

cuboidal epithelial cells

Question 17

what in the PCT increases SA

Answer 17

microvilli

Question 18

describe the process of selective reabsorption

Answer 18

1) na+ and glucose enter the PCT through co-transport proteins
2) water potential of cell lowered so water enters cell by osmosis
3) 3 Na+ out and 2k+ in, glucose is facilitated diffusion into the blood
4) wp of blood lowered, water moves into blood
5) large molecules are removed by endocytosis

Question 19

the deeper into the medulla you go….

Answer 19

the lower the WP

Question 20

describe the UPPER part of the descending limb

Answer 20

it is impermeable to water but the lower part is permeable to water but impermeable to salts

Question 21

describe the ascending limb of the loop of henle

Answer 21

permeable to salts but impermeable to water

Question 22

describe the collecting duct

Answer 22

impermeable to salts but permeable to water

Question 23

describe what processes occur in the descending limb

Answer 23

water is lost from fltrate by osmosis, goes into the blood

Question 24

describe the processes in the ascending limb

Answer 24

bottom- salts diffuse out
upper- ions are actively transported out into the medulla
this gives a higher water potential to filtrate= more dilute

Question 25

what processes happen in the DCT

Answer 25

sodium ions are reabsorbed and K+ and H+ ions are added into dct

Question 26

what happens in the collecting duct

Answer 26

water is lost from filtrate by osmosis from collecting duct, as deeper into medulla= lower WP, some urea moves out as well.

Question 27

what is the name for the term given when two limbs run close to each other in opposite direction

Answer 27

hair pin counter current multiplier

Question 28

describe the loop of henle in desert animals

Answer 28

longer loop of henle lowering medulla water potential urine has a lower water potential and is more concentrated

Question 29

what happens if the body lacks salt

Answer 29

sodium ions are actively transported out of the DCT with chloride ions

Question 30

what happens in the DCT if ADH has been released

Answer 30

the walls of the dct also become more permeable to water and water leaves

Question 31

what hormone regulates osmoregulation | where is it released from and where does it target

Answer 31

antidiuretic hormone released from pituitary gland targets collecting ducts

Question 32

how does hypothalamus monitor water potential

Answer 32

osmoreceptors

Question 33

what would happen if water potential was too low

Answer 33

water potential drops too low: 1) ADH is released from the posterioir pituitary cells when it is stimulated by osmoreceptors in the hypothalamus 2) ADH secreted into blood 3) binds to complimentary receptors on collecting duct 4) increases the number of aquaporins ( protein channels) in membrane. activates a series of reactions (via cAMP)= formation of vesicles with aquaporins to fuse with membrane 5) more aquaporins so more water moves by osmosis into the tissue fluid

Question 34

what would happen when baroreceptors detect a rise in blood pressure, in terms of adh production

Answer 34

decreases, more water in blood would increase pressure further

Question 35

why does kidney failure occur

Answer 35

glomeruli become inflamed and swollen due to: - diabetes mellitus - hypertension- damages structure of basement membrane - infection- podocytes and tubules become damaged - genetic conditions- kidney tissue has fluid filled cysts

Question 36

what is found in the urine if the kidneys are infected

Answer 36

proteins and blood cells

Question 37

what happens when kidneys fail

Answer 37

unable to remove excess ions, urea and water

Question 38

what is used to measure kidney function, how do they do this

Answer 38

glomerular filtrate rate a blood test measures levels of creatinine in the blood, if this increases it is a sign that kidneys are not functioning properly

Question 39

evaluate using this blood test to measure glomerular filtrate rate

Answer 39

advantages: produced at a constant rate per day freely filtered at the glomerulus disadvantages: estimate 10% secreted by tubules

Question 40

describe the process of renal dialysis

Answer 40

1) blood leaves the artery, a anticoagulant drug is given to prevent clots in the machine 2) blood passes in the oposite direction to maintain a conc gradient for diffusion, waste molecules diffuse across membrane, water by osmosis 3) air detector stops any air bubbles entering the persons blood ( could be fatal) , clean blood enters the vein 4) excess urea and mineral ions must leave the blood 5) anti coagulant drug stops to allow blood to clot normally

Question 41

describe the process of peritoneal dialysis

Answer 41

where fluid of correct concentrations is pumped into abdomen wall, between the wall and peritoneum membrane (acts as a partially permeable membrane) waste materials move into dialysate pro: can be done at home

Question 42

evaluate kidney transplants

Answer 42

advantages: no time consuming dialysis no longer chronically ill can travel cons: immunosuppressant drugs for life major surgery risk of infection

Question 43

name the genetic marker on human tissue | what does this mean for transplants

Answer 43

human leukocyte antigen | should recieve a transplant from someone with an identical or similar HLA

Question 44

``` what if present in urine is a symptom for: diabetes mellitus muscle damage pregnancy ovulation ```

Answer 44

glucose creatine human chorionic gonadotropin luteinising hormone

Question 45

what are monoclonal antibodies

Answer 45

antibodies that are from a single clone of cells that are produced to target particular cells or chemicals in the body

Question 46

how are monoclonal antibodies for hcg produced

Answer 46

1) a mouse is injected with HCG to make the required antibody 2) B cells that make the required antibody are removed from mouse spleen 3) b cells are fused with myeloma cells which do not divide very rapidly 4) a hybridoma is formed, reproduces rapidly 5) each hybridoma produces the desired antibody, collected and purified for use

Question 47

explain how a pregnancy testing kit detects the pregnancy hormone

Answer 47

1- testing for hcg 2- hormone is so small it passes from blood into filtrate 3) free monoclonal antibodies complimentary to hcg bind 4) other immobilised monoclonal antibodies in the test window bind to hcg stopping hcg and antibody with dye 5) more immobilised antibodies in the control window bind only to the antibody with the dye to show that the test is working

Question 48

describe the process of random sampling to athletes for drugs

Answer 48

urine sample taken, vapourised with a gas solvent, passed into a gas chromatography machine, gas solvent dissolves the substance allowing a chromatogram to form

Question 49

pros and cons of steroids

Answer 49

pros, can train for longer, respire for longer, build muscle quicker cons, depression, anger, liver damage, heart attacks