Physiology 2

Question 1

the 10 functions of the kidneys

Answer 1

1. water balance
2. salt balance
3. Maintenance of plasma volume
4. Maintenance of plasma osmolarity
5. Acid-base balance
6. Excretion of metabolic waste products
7. Excretion of exogenous foreign compounds
8. secretion of renting to maintain arterial blood pressure
9. secretion fo erythropoietin which is required to produce red blood cells
10. Conversion fo 25- hydroxyvitamin D3 (cholecalciferol) to 1,25-hydroxyvitamin D3 (CALCITRIOL)

Question 2

primary function of the kidney

Answer 2

is to regulate the volume, composition and osmolarity of body fluids

Question 3

concept of homeostasis for any substance

Answer 3

input has to equal output which can be applied to Na+, K+, Ca2+, Cl- and PO42- so the kidney controls the excretion of these substances in order to maintain homeostasis

Question 4

blood enters the kidney

Answer 4

via the renal artery

Question 5

blood drains from the kidney

Answer 5

via the renal vein

Question 6

what is the functional unit of the kidney

Answer 6

the nephron

Question 7

the first part of the nephron is

Answer 7

the glomerulus

Question 8

the glomerulus receives

Answer 8

branches of the renal artery called the afferent arteriole and exiting the glomerulus is the efferent arteriole

Question 9

the glomerulus function is

Answer 9

filtration of the blood, blood flows through the glomerulus and small molecules bass into bowmans space where it is known as the filtrate

Question 10

how does the filtrate get from the afferent arteriole into bowmans space

Answer 10

• the afferent arteriole is lined with endothelial cells which contains fenestrations which allows small molecules to pass through but prevents larger proteins passing through
• underneath the endothelial cells is the basement membrane which is negatively charge and repels larger proteins such as albumin inhibiting them from passing through
• on the inner layer of bowmans capsule there is a type of epithelial cell called podocytes which extend there foot processes onto the endothelial cells which ensures they tightly adhere to one another

Question 11

increasing the diameter of the afferent arteriole

Answer 11

more blood can pass through the glomerulus and the glomerular filtration rate increases

Question 12

reducing the diameter of the afferent arteriole

Answer 12

less blood can pass through the glomerulus and the glomerular filtration rate falls

Question 13

after blood has been filtrated in the glomerulus

Answer 13

it flows through the proximal convoluted tubule

Question 14

the proximal convoluted tubule is very important for

Answer 14

the re-abdsorption of ions like sodium, chloride, amino acids and glucose and it also re-abdorbs water

Question 15

after the proximal convoluted tubule the filtrate passes into

Answer 15

the descending loop of henle and then into the ascending loop of henle

Question 16

descending limb of the loop of henle is

Answer 16

impermeable to ions and ONLY re-absorbs water

Question 17

ascending limb of the loop of henle is

Answer 17

impermeable to water and ONLY re-absorbs ions

Question 18

the process occurring in the loop of henle is known as

Answer 18

counter-currant multipiclation

Question 19

why is it called counter-currant

Answer 19

because the loop of henley are travelling in opposite directions

Question 20

why is it called multipiclation

Answer 20

because the process of re-absorption of ions in the ascending loop of henle is active and by making the renal medially more acidic, it allows the passive movement of water from the descending limb into the intersitium which is a completely passive process

Question 21

fluid then flows from

Answer 21

the ascending loop of henle into the distal convoluted tubule

Question 22

the distal convoluted tubule re-absorbs

Answer 22

sodium and chloride

Question 23

where the distal convoluted tubule passes the glomerulus

Answer 23

this is called the jucto-glomerual apparatus

Question 24

the junta-glomerular apparatus

Answer 24

is the part of the kidney which controls blood pressure

Question 25

from the distal convoluted tubule the filtrate then flows into the

Answer 25

collecting ducts

Question 26

the collecting ducts collects filtrate from

Answer 26

many distal convoluted tubules

Question 27

what is urea

Answer 27

one of the main waste components in the urine, but the kidney does reliant some in a process called urea recycling in order to increase the osmolarity of the renal medially which increases water re-absorption in the descending loop of henle

Question 28

the efferent arteriole gives of

Answer 28

many branches called peri-tubular capillaries which cross all over the nephron and pick up everything that has been re-absorbed from the lumen of the nephron into the interstitial to return it back to the renal vein

Question 29

how much os the plasma entering the glomeruli gets filtered

Answer 29

only 20% the remaining 80% leaves via the efferent arteriole

Question 30

cells facing the inside of the lumen are on the

Answer 30

apical side

Question 31

cells on the opposite side of the lumen are on the

Answer 31

base-lateral side

Question 32

attached to the base-lateral side is the

Answer 32

peri-tubular capillaries

Question 33

how does re-absorption take place in the proximal convoluted tubules

Answer 33

on the apical surface there are co-transporters so because sodium is actively transported via the sodium potassium ATP ASE pump, eventually there will be less sodium in the cell than in the lyme so sodium will wanto to move down its concentration gradient out of the lumen so this energy gets use to transport glucose out of the lumen down its concentration gradient to be re-absorbed into the blood

Question 34

how does re-absorption take place in the ascending loop of henle

Answer 34

there is the same sodium potassium pump so as sodium is transported out of the lumen there is a NA+/K+/Cl- co-transporter which is a form of secondary active transport so sodium, potassium and chlorine get re-absorbed

Question 35

how does re-absorption take place in the distal convoluted tubules

Answer 35

sodium potassium pump causes movement of sodium out of the lumen into the blood, apical membrane contains calcium pores so calcium concentration in the cell is equal to that of the calcium in the lumen, but there is an ante-porter so sodium gets pumped back into the tubule and calcium is pumped into the urine

Question 36

what actually is urine

Answer 36

modified filtrate of blood

Question 37

the 3 main functions of a nephron

Answer 37

1. filtration 2. re-absorption 3. secretion

Question 38

for any substance filtration and tubular secretion is equal to

Answer 38

tubular reabsorption and excretion

Question 39

rate of excretion is equal to

Answer 39

the rate of filtration+ rate of secretion- rate of re-absorption

Question 40

movement of substances within the kidney are described in terms of

Answer 40

concentration x flow

Question 41

rate of filtration of a substance X is

Answer 41

mass of substance X filtered into bowmans capsule per unit time

Question 42

for a freely filterable substance X the rate of filtration of X is equal to

Answer 42

the concentration of X in the plasma multiplied by the glomerular filtration rate

Question 43

rate of excretion of substance x is

Answer 43

the mass of substance X excreted per unit time

Question 44

rate of excretion of substance X is equal to

Answer 44

the consternation of X in the urine multiplied by the urine flow rate

Question 45

rate of reabsorption of a substance

Answer 45

if the rate of filtration is greater than the rate of excretion then net reabsorption has occurred

Question 46

rate of re-absorption of substance X

Answer 46

rate of filtration of substance X- rate of excretion of substance X

Question 47

rate of secretion of a substance

Answer 47

if the rate of filtration of a substance is less than the rate of excretion then net secretion of the substance has occurred

Question 48

rate of secretion

Answer 48

rate of excretion- rate of filtration

Question 49

rate of filtration and excretion are

Answer 49

relatively easy to measure

Question 50

rate of reabsorption and secretion reflect

Answer 50

tubular modification of the filtrate obtained as the different between the rate of filtration and the rate of excretion