functioning of the kidneys

Question 1

where does the blood in the capillaries of the glomerulus come from

Answer 1

from the afferent arteriole which is a branch of the renal artery

Question 2

what does the blood in the capillaries of the glomerulus contain

Answer 2

1) water
2)salt
3) useful substances such as glucose , amino acids ,fatty acids and glycerol
4)waste substances such as urea an uric acids
5) and the normal constituents of blood ( blood plasma ,red and white blood corpuscles ,plasma proteins such a fibrinogen , albumin and globulin

Question 3

how do some of these substances pass into the capsular space of bowman’s capsule

Answer 3

by glomerulus filtration

Question 4

why is blood in the glomerulus under great pressure

Answer 4

because the afferent arteriole is wider than the efferent ar

Question 5

what happens to the substances of the blood in the glomerulus as a result of the great pressure in the glomerulus

Answer 5

they are forced out through tiny pores on the capillary walls

Question 6

the function of the podocytes , with slit pores between them

Answer 6

act as a selective filter allowing only fairly small particles to pass through

Question 7

name the substances that are able to pass through the pores on the capillaries and slit pores on the podocytes

Answer 7

• water
• glucose
• amino acids
• urea
  *uric acid
• salts

Question 8

what does not filter through

Answer 8

blood corpuscles and plasma protein

Question 9

glomerulus filtrate

Answer 9

the liquid which is in the capsular space of bowmans capsule

Question 10

what happens to the glomerulus filtrates

Answer 10

it passes down the renal tubule where reabsorption and tubular excretion occurs

Question 11

what happens in the second capillary network

Answer 11

some water and almost all the glucose and other useful substances are selectively re absorbed by the second capillary network

Question 12

dilute urine

Answer 12

the filtrate which enter the loop of Henle

Question 13

function of the loop of henle

Answer 13

to ensure that the renal medulla always has a high concentration of sodium ions

Question 14

where is the soduim ions pumped out of

Answer 14

it is pumped out of the loop of henle into the tissue fluid of the medulla

Question 15

what does the pumped out sodium ions allow

Answer 15

this enables water to leave the ascending limb , distal convoluted tubule and collecting tubule by osmosis and enter the renal medulla i.e. water is conserved

Question 16

what is the fluid in the collecting tubule

Answer 16

it is a highly concentrated urine

Question 17

adh

Answer 17

a hormone that controls the actual amount of water re absorbed

Question 18

function of the epithelium of the tubules

Answer 18

1) they absorb useful substances from the filtrate and passing them into the blood capillaries
2) excretes

Question 19

what wastes do the epithelium of the tubule excretes

Answer 19

1) ammonia
2) creatinine
3) potassium , hydrogen , sodium and bicarbonate ions
4) certain drugs

Question 20

what happens when blood is too acidic ( ph is too low )

Answer 20

1) more hydrogen ions are excreted from the blood into the renal tubule
2) more bicarbonate ions are reabsorbed into the blood
3) in this way the ph of the blood is increased until it becomes normal

Question 21

what happens when the blood is too basic ( ph is too high )

Answer 21

less hydrogen ions are excreted from the blood into the renal tubule
2) less bicarbonate ions are re absorbed into the blood
3) in this way the ph of the blood is decreases until it becomes normal

Question 22

what happens when there is a shortage of sodium in the blood

Answer 22

1) the adrenal cortex secrets more aldosterone
2) therefore more sodium is re absorbed by the blood capillaries at the distal and collecting tubules and less sodium ions are excreted
3) in this way the amount of sodium id raised until it comes back to normal

Question 23

what happens when there is an excess of sodium ions in the blood

Answer 23

1) aldosterone secretion decreases
20 therefore the less sodium is re absorbed by the blood capillaries
3) this allows more sodium to be excreted
4) the amount of sodium in the blood is decreased until it gets back to normal

Question 24

where is the urine temporarily stored

Answer 24

from the collecting tubules the urine passes into the renal pelvis and then down the ureters into the bladder where it is temporarily stored

Question 25

urination

Answer 25

the process whereby from time to time the bladder is emptied by the urine passing along the urethra to the outside

Question 26

what is urination as a result of

Answer 26

an involuntary and a voluntary process

Question 27

involuntary process

Answer 27

the parasympathetic nerve fibers in the bladder wall cause the bladder to contract and the internal sphincter to relax

Question 28

voluntary action

Answer 28

before urination can begin the external sphincter relaxes

Question 29

what controls the voluntary action

Answer 29

under the command of the cerebrum , the brain therefore controls this action