9.3 2 Osmoregulation in mammals-the kidney

Question 1

water moves in and out of cells

Answer 1

by osmosis

Question 2

Osmoregulation definition

Answer 2

the maintenance of a constant osmotic potential in the tissues of living organism by controlling water and salt concentrations

Question 3

By controlling the water potential of the blood

Answer 3

body can control the water potential of the tissue fluid and protect the cells from osmotic damage

Question 4

deamination definition

Answer 4

the removal of the amino group from excess amino acids in the ornithine cycle in the liver .

Question 5

body

Answer 5

cannot store protein or amino acids and without the action of the liver any excess protein you eat would be excreted and wasted

Question 6

hepatocytes (liver cells)

Answer 6

deaminate excess amino acids
remove amino group (NH2)
convert to ammonia which is very toxic
then very quickly to less toxic urea

Question 7

ammonia produced in deamination process

Answer 7

converted into urea by a series of enzyme controlled reactions known as ornithine cycle
remainder of amino acid can then be used for celluar respiration or converted into lipid for storage

Question 8

amino acid +oxygen

Answer 8

keto acid +ammonia (ammonia then goes to ornithine cycle)

Question 9

Urine produced

Answer 9

is more concentrated (hypertonic to) the body fluids –makes it possible to conserve water

Question 10

where are kidneys

Answer 10

attached to the back of abdominal cavity

surrounded by a thick layer of fat which helps prevent them from mechanical damage

Question 11

kidneys purpose

Answer 11

control water potential of the blood removing substances that would affect the water balance as well as getting rid of urea- urea ,excess salts and water is removed

Question 12

the urine

Answer 12

is stored in the bladder and released from the body in regular intervals

Question 13

cortex

Answer 13

rich capillary network contains malpighian bodies of all the nephrons

Question 14

pelvis

Answer 14

central chamber where urine arrives from collecting ducts

Question 15

two roles of kidney in body

Answer 15

remove urea and osmoregulation

Question 16

cortical nephrons

Answer 16

found in renal cortex have loop of Henle that only just reaches into medulla (majority)

Question 17

Juxtamedullary nephrons

Answer 17

have long loops of Henle that penetrate right through the medulla -particularly efficient at producing conctrated urine

Question 18

Three processes of osmoregulation

Answer 18

ultrafiltration ,selective reabsorption and tubular secretion

Question 19

why does ultrafiltration occur

Answer 19

high blood pressure in the glomerular capillaries and the structure of Bowmans capsule and glomerulus

Question 20

Malpighian body

Answer 20

combination of Bowman’s capsule and the glomerulus

Question 21

how is there a high blood pressure

Answer 21

because diameter of blood vessel coming into glomerulus (afferent arteriole) is greater then blood vessel leaving (efferent arteriole)

Question 22

the high blood pressure

Answer 22

squeezes blood out through pores in the capillary wall-size of pores mean almost all the contents of the plasma can pass out of the capillary -only blood cells and the largest plasma proteins cannot get through the pores

Question 23

cells of Bowman’s capsule

Answer 23

act as an additional filter -wall of capsule made up of special cells called podocytes. They have extensions called pedicles that wrap around the capillaries forming slits that ensure any cells platelets or large plasma proteins that have left the capillary do not get into the tubule itself

Question 24

Filtrate that enters bowmans capsule

Answer 24

contains glucose ,salt ,urea and many other substances in the same concentration as they are in the blood plasma

Question 25

ultrafiltration

Answer 25

is passive and indiscriminate -removes urea from blood but also a lot of water as well as glucose,salt and other

Question 26

proximal convoluted tubule

Answer 26

cells lining tubule have microvilli that greatly increase surface area through which substances can be absorbed -have large numbers of mitochondria indicating this is an active process

Question 27

what is moved back into the blood by active transport

Answer 27

glucose,amino acids ,vitamens and most hormones

Question 28

sodium ions

Answer 28

are actively transported and chloride and water ions follow passively along the gradient

Question 29

once substances removed from tubule cells

Answer 29

into intracellular spaces they diffuse into the capillary network that surrounds the tubules

Question 30

time filtrate reaches loop of Henle

Answer 30

isotonic to fluid that surrounds the tubule

Question 31

loop of Henle

Answer 31

found in medulla of kidneys in close contact with network of capillaries known as the vasa recta

Question 32

creation of high concentration of sodium and chloride ions in the tissue fluid of the medulla

Answer 32

is due to the flow of fluid in opposite directions in the adjacent limbs of the loop of Henle combined with different permeabilities to water in different sections and a region of active transport

Question 33

Countercurrent multiplier

Answer 33

A system that produces a concentration gradient in living organisms using energy from cellular respiration

Question 34

Descending limb

Answer 34

Freely permeable to water but not permeable to sodium and chloride ions
No active transport
The fluid entering here is isotonic with the blood
As travels down limb into medulla external concentration of sodium and chloride ions in tissue fluid of medulla and the blood of the vasa recta is higher and higher
Water moves out into the blood of vasa recta down water potential gradient
By time at bottom the loop is very concentrated are hypertonic to arterial blood

Question 35

The first section ascending limb

Answer 35

First section of the limb is very permable to sodium and chloride ions but not to water
No active transport takes place in this section
Sodium ions and chloride ions move out the very concentrated fluid in the loop of Henle into tissue fluid of medulla

Question 36

The second section of the ascending limb

Answer 36

Impermeable to water
Thicker
Sodium ions and chloride ions are actively pumped out of the tubule into the tissue fluid of the medulla and the blood of vasa recta a
Gives tissue of medulla the very high sodium and chloride ion concentration which causes water to pass out the descending limb
Fluid left in ascending limb becomes less concentrated

Question 37

Distal convoluted tubule

Answer 37

Permable to water

Question 38

Distal convoluted tubule and collecting duct

Answer 38

Balancing of the water of the body takes place

If not enough salt in body sodium may be pumped out of tubule with chloride ions following

Question 39

The collecting duct

Answer 39

Water moves out of the collecting duct down a water potential gradient as passes through medulla
Urine becomes steadily more concentrated
Allows creation of hypertonic urine

Question 40

Kangaroo rat

Answer 40

Spend time in in burrows where temperature is cooler
Generate majority of water by oxidative methods
Large portion of juxtamedullary nephrons
Long loops of henle - particularly descending loop
Higher numbers of infoldings in the cell membranes of the epithelial cells lining the tubules
Higher number of mitochondria

Question 41

Under a microscope the proximal convoluted tubule will appear

Answer 41

Fuzzy

Question 42

The distal convoluted tubule

Answer 42

Will appear clear

Question 43

Glomeruous

Answer 43

Will appear under a microscope concentrated red blood cells

Question 44

Barrier between blood in capillary and lumen of bowmans capsule

Answer 44

Three layers

1. Endothelium of capillary - narrow gaps between cells blood plasma can pass through
2. Basement membrane - fine mesh of collagen fibres and glycoproteins prevent big molecules passing through
3. Epithelial cells of bowmans capsule - specialised shape and finger like projections ensure any gaps between cells allowing fluid to pass into the lumen of bc