5.1.2 (c) the Kidney

Question 1

what 2 homeostatic roles do the kidneys play in the body?

Answer 1

excretion
osmoregulation

Question 2

how are the kidneys involved in excretion?

Answer 2

they filter nitrogenous waste out of the blood

Question 3

how are the kidneys involved in osmoregulation?

Answer 3

by helping maintain water balance and the pH of the blood

Question 4

what vessel carries blood into the kidneys?

Answer 4

the renal arteries which branch off of the aorta

Question 5

which vessel carries blood out of the kidneys?

Answer 5

renal vein which drains into the vena cava

Question 6

what are the kidneys composed of?

Answer 6

nephrons which are filtering units

Question 7

what liquid is produced by the kidney tubules?

Answer 7

urine

Question 8

what does the urine leave the kidney in?

Answer 8

the ureter

Question 9

what does the ureter lead to?

Answer 9

the bladder

Question 10

how does urine leave the bladder?

Answer 10

through the urethra and out of the body

Question 11

what are the 3 main areas of the kidney?

Answer 11

cortex
medulla
pelvis

Question 12

what happens in the kidney cortex?

Answer 12

site of ultrafiltration

Question 13

what happens in the kidney medulla?

Answer 13

selective reabsorption and osmoregulation

Question 14

what happens in the kidney pelvis?

Answer 14

where the urine collects and then passed into the ureter

Question 15

what are the 5 regions of a nephron?

Answer 15

bowman’s capsule
proximal convoluted tubule
loop of Henle
distal convoluted tubule
collecting duct

Question 16

what is the bowman’s capsule?

Answer 16

contains the glomerulus which is where ultrafiltration takes place

Question 17

what is the proximal convoluted tubule?

Answer 17

coiled region following the bowman’s capsule where selective reabsorption begins

Question 18

what is the loop of Henle?

Answer 18

long loop with an ascending and descending loop where selective reabsorption takes place

Question 19

what is the distal convoluted tubule?

Answer 19

second coiled region following the loop of Henle where osmoregulation occurs with its wall’s permeability affected by ADH levels

Question 20

what is the collecting duct?

Answer 20

moves urine down the medulla and into the pelvis as well as more osmoregulation

Question 21

what are the 3 functions of the nephrons?

Answer 21

ultrafiltration
selective reabsorption
osmoregulation

Question 22

what supplies the glomerulus with blood?

Answer 22

afferent arteriole

Question 23

what forces blood out through the capillary walls of the glomerulus?

Answer 23

the greater pressure created by the efferent arteriole

blood moves from a high pressure to a low pressure through fenestrations in the glomerulus

Question 24

what does the blood leave the glomerulus in?

Answer 24

efferent arteriole

which is narrower and therefore creates greater pressure

Question 25

what are the three layers between the capillary and Bowman's capsule?

Answer 25

capillary endothelium basement membrane podocytes

Question 26

what are found in the capillary endothelium to control entry of blood?

Answer 26

fenestrations to prevent large molecules from passing through

Question 27

what is the basement membrane?

Answer 27

acts as a second sieve by filtering out the plasma contents

Question 28

what cannot pass through the basement membrane and why?

Answer 28

plasma proteins and red blood cells they are both too large to fit through...

Question 29

what effect does the plasma proteins remaining in the blood have on the capillaries?

Answer 29

this creates a low water potential which allows for water to move back into the blood later

Question 30

what are podocytes?

Answer 30

specialised cells which wrap around the capillaries and form slits to prevent large molecules from passing through

Question 31

what do podocytes filter out?

Answer 31

any cells, platelets or large plasma proteins which have managed to get through the epithelial and basement membrane

Question 32

order of 3 part filter

Answer 32

glomerulus endothelium basement membrane podocytes

Question 33

what does the filtrate after the bowman's capsule contain?

Answer 33

salt glucose urea water

Question 34

why does selective reabsorption occur?

Answer 34

to bring back necessary substances which have been removed from the blood, back into the blood

Question 35

where does selective reabsorption occur?

Answer 35

at the proximal convoluted tubule

Question 36

what is reabsorbed at the proximal convoluted tubule?

Answer 36

sodium chloride water glucose amino acids

Question 37

how are glucose and amino acids removed from the filtrate at the proximal convoluted tubule?

Answer 37

by active transport

Question 38

how are sodium ions removed from the filtrate at the proximal convoluted tubule?

Answer 38

pumped out by active transport

Question 39

how are chloride ions and water removed from the filtrate at the proximal convoluted tubule?

Answer 39

passively down a concentration gradient

Question 40

what are the adaptations of the proximal convoluted tubule?

Answer 40

- covered with microvilli which increase the SA so more substances can be reabsorbed - have many mitochondria to provide ATP for active transport - epithelium lines walls

Question 41

where do the reabsorbed materials go after being reabsorbed?

Answer 41

they diffuse into extensive capillary network which has a steep concentration gradient between them which is maintained by a constant flow of blood

Question 42

what does Loop of Henle act as?

Answer 42

acts as a countercurrent multiplier by using energy to produce a concentration gradient that allows for the movement of substances

Question 43

what happens to Na+ and Cl- ions in the descending loop?

Answer 43

they stay in the filtrate as the walls are impermeable to Na+ and Cl- makes the filtrate very concentrated

Question 44

what happens to Na+ and Cl- in the ascending limb?

Answer 44

Na+ and Cl- ions are pumped out into the medulla at the top Na+ and Cl- ions diffuse into the medulla at the bottom this makes the water potential in the medulla lower filtrate leaves very dilute

Question 45

as the water potential of the medulla is lower what happens at the top of the descending limb?

Answer 45

water moves into the medulla by osmosis from high water potential to low water potential water is reabsorbed into the blood via capillaries

Question 46

as the water potential of the medulla is lower what happens to the collecting duct?

Answer 46

water moves out by osmosis and then reabsorbed into the blood via capillaries

Question 47

what stops water and ions re-entering the Loop of Henle at the ascending loop?

Answer 47

it is impermeable to water

Question 48

what is the role of the distal convoluted tubule?

Answer 48

site of water balancing controls the pH levels

Question 49

what hormone are the walls of the DCT affected by?

Answer 49

ADH

Question 50

what organelle is found in excess in the DCT and why?

Answer 50

contain a lot of mitochondria to power active transport

Question 51

what is pumped out of the filtrate at the DCT when salt conc is low?

Answer 51

Na+ ions and Cl- ions are actively pumped back into the blood to restore salt conc

Question 52

what is the function of the collecting duct?

Answer 52

more osmoregulation walls effected by ADH water moves out by diffusion

Question 53

why cant podocytes underogo mitosis?

Answer 53

they are specialised so remain in G0 therefore formation of spindle fibres and mitosis cannot occur

Question 54

features of glomerulus

Answer 54

efferent arteriole more narrower than afferent causes a high hydrostatic pressure forces filtrate to form in bowman’s capsule fenestrations in the endothelium are small prevent large plasma proteins and RBCs from entering