Physiological Functions of the Kidneys

Question 1

roles of the kidneys

Answer 1

regulating fluid volume
regulating conc. of electrolytes
regulation of acid-base balance
excreting waste
conserving nutrients
hormone secretion

Question 2

which hormones and enzymes are secreted by the kidneys

Answer 2

erythropoetin - hormone
calcitriol - hormone
renin - enxyme

Question 3

when is erythropoeitin released and what is its function

Answer 3

in response to hypoxia in the renal circulation
it stimulates erythropoiesis (RBC production) in the bone marrow

Question 4

what is the role of calcitriol

Answer 4

it is the activated form of vitamin D and it promotes intestinal absorption of calciu,

Question 5

what is the role of calcitriol

Answer 5

it is the activated form of vitamin D and it promotes intestinal absorption of calcium

Question 6

what is the role of renin and where and when is it released?

Answer 6

released from juxtaglomerular apparatus
released in response to reduction in tubular flow or sodium content
regulates angiotensin and aldosterone levels which control blood pressure

Question 7

what functions of the kidney play a crucial role in blood pressure control?

Answer 7

renin release
regulation of fluid volume and plasma electrolytes

Question 8

what muscle needs to relax to allow urine to drain through the urethra and is it voluntary or involuntary

Answer 8

sphincter muscle
voluntary

Question 9

what two layers surround the kidneys

Answer 9

renal fascia - tough connective tissue
capsule of peri-renal fat

Question 10

what structures are found in the renal hilum

Answer 10

first part the ureter
nerves
arteries and veins

Question 11

what is the basic functional unit of the kidney

Answer 11

nephron

Question 12

how many nephrons are in a kidney

Answer 12

~1 million

Question 13

what is urea

Answer 13

the nitrogen containing end product of protein metabolism

Question 14

what part of the body has the most control over the hydration status of the body

Answer 14

the kidneys

Question 15

what is the glomerulus and what is it enclosed within

Answer 15

a bundle of specialised capillaries with a permeable membrane
enclosed within Bowman’s capsule

Question 16

which type of arteriole supplies the glomerulus and which type returns contents to the systemic circulation

Answer 16

afferent supplies
efferent drains

Question 17

what percentage of sodium and chloride are reabsorbed in proximal convoluted tubule

Answer 17

65%

Question 18

what is recovered in the PCT

Answer 18

sodium, potassium, calcium, magnesium
phosphate and chloride ions
bicarbonate
glucose
amino acid
urea
water

Question 19

how are sodium, potassium and chloride reabsorbed in the PCT

Answer 19

by passive transport

Question 20

how is glucose reabsorbed in the PCT

Answer 20

cotransported with sodium

Question 21

how are calcium and magnesium reabsorbed in the PCT

Answer 21

they compete for exchange with sodium ions

Question 22

how is phosphate reabsorbed in the PCT

Answer 22

reabsorbed with sodium

Question 23

how is water reabsorbed in the PCT

Answer 23

osmotically with solutes through aquaporin channels
water follows movement of solutes

Question 24

what is actively excreted in the PCT

Answer 24

creatinine, uric acid and many drugs

Question 25

where does the loop of henle descend into and what is a key characteristic of this region

Answer 25

the renal medulla it is highly concentrated

Question 26

what is reabsorbed in the descending limb of LoH

Answer 26

water

Question 27

how is water reabsorbed in the DL or LoH

Answer 27

by osmosis as the extratubular concentration is high

Question 28

how is the high concentration maintained in the renal medulla

Answer 28

by countercurrent exhange process where urea is recycled between the tubules and interstirium

Question 29

what is reabsorbed in the ascending limb of LoH

Answer 29

sodium, potassium and chloride ions calcium and magnisum ions

Question 30

how is sodium, potassium and chloride reabsorbed in the LoH

Answer 30

by a specialised symporter protein which transports a sodium ion, two chloride ions and a potassium ion

Question 31

how is calciuma and phosphate reabsorbed in the ascending limbd og LoH

Answer 31

passive transport

Question 32

what percentage of sodium and chloride are reabsorbed in the DL of LoH

Answer 32

0%

Question 33

what percentage of sodium and chloride are reabsorbed in the AL of LoH

Answer 33

25%

Question 34

what percentage of sodium and chloride are reabsorbed in the DCT

Answer 34

10%

Question 35

what is reabsorbed in the DCT

Answer 35

sodium and chloride ions calcium

Question 36

how are sodium and chloride ions reabsorbed in the DCT

Answer 36

in first part - by symporter protein in second part - sodium reabsorbed in exchange for excretion of potassium or hydrogen

Question 37

what stimulates the reabsorption of sodium in exchange for excretion of potassium or hydrogen in the distal part of the DCT

Answer 37

aldosterone

Question 38

what is the function the reabsorption of sodium in exchange for excretion of potassium or hydrogen in the distal part of the DCT

Answer 38

regulation of pH of the urine and body

Question 39

what stimulates calcium reabsorption in the body

Answer 39

parathyroid hormone

Question 40

what is reabsorbed in the collecting duct

Answer 40

sodium water

Question 41

what is osmolality

Answer 41

the relative proportions of salt and water in the body

Question 42

what structure detects significant rises in plasma osmolality

Answer 42

hypothalamus

Question 43

how does the body respond to a significant rise in plasma osmolality

Answer 43

1. hypothalamus detects it 2. communicates with posterior pituitary gland 3. vasopressin/ADH released 4. vasopressin causes aquaporins to translocate to the membrane of the collecting duct cells 5. this allows water to cross the normally impermeable membrane and be reabsorbed in the body by the vasa recta 6. this increases the plasma volume of the body

Question 44

what lies next to the afferent arteriole in each glomerulus and why

Answer 44

ascending limb of LoH allows for specialised tubular cells called the macula densa to provide feedback regulartion in response to changes in the tubular content of water and electrolytes

Question 45

when is the renin angiotensin system activated

Answer 45

hypotension hypovolaemia

Question 46

where is the macula densa found

Answer 46

between LoH and DCT

Question 47

what type of cells make up the macula densa

Answer 47

juxtaglomerular cells

Question 48

what are juxtaglomerular cells sensitive to

Answer 48

the concentration of sodium chloride in tubular fluid the pressure in the afferent arteriole signals from sympathetic nervous system

Question 49

an increase/decrease of sodium chloride concentration stimulates release of renin

Answer 49

deccrease

Question 50

what reaction does renin catalyse

Answer 50

angiotensinogen -> angiotensin I

Question 51

what enzyme catalyses angiotensin I -> angiotensin II

Answer 51

angiotensin converting enzyme

Question 52

what type of drug inhibits the formation of angiotensin II

Answer 52

ACEi (e.g. ramipril)

Question 53

how does angiotensin increase blood pressure

Answer 53

constricts efferent arteriole to increase glomerular capillary pressure and filtration systemic vasconstriction stimulates thirst stimulate release of vasopressin which conserves water stimulates release of aldosterone which conserves sodium

Question 54

what hormone is in charge of sodium conservation and where is it released from

Answer 54

aldosterone adrenal cortex

Question 55

what hormone is in charge of water conservation and where is it released from

Answer 55

vasopressin posterior pituitary

Question 56

what is the GFR a measure of

Answer 56

the performance of the kidneys volume of plasma filtered at the kidneys every minute

Question 57

what is a typical GFR of a healthy adult

Answer 57

120mL/minute

Question 58

how much kidney function is lost with healthy ageing

Answer 58

can be up to 50% in 80 year old

Question 59

what are the consequences of reduced kidney function due to disease

Answer 59

reduced clearance of waste products, ions, drugs, water and acid uraemia and reduced erythropoietin formation -> anaemia phosphate retention and failure to convert precursors to vitamin D -> renal bone disease

Question 60

what are the three categories of acute renal impairment

Answer 60

pre-renal renal post renal

Question 61

why does pre-renal renal impairment occur

Answer 61

failure of sufficient blood flow getting to the kidneys

Question 62

common causes of pre renal renal impairment

Answer 62

systemic dehydration due to illness or diuretics low arterial blood pressure due to drugs or haemorrhage blockage of major renal arteries due to atherosclerosis or thrombosis vasoconstriction of cortical vessels because of drugs (e.g. NSAIDs)

Question 63

what are renal causes of renal impairment

Answer 63

intrinsic renal disease or damage due to drugs or other toxins

Question 64

what are post renal causes of renal impairment

Answer 64

renal impairment due to obstruction of the urinary tract commonly due to - compression of ureter between kidney and bladder as a result of tumour - obstruction of bladder outflow (e.g. due to prostate disease)

Question 65

is damage caused by AKI reversible

Answer 65

yes, usually but may result in permanent reduction in baseline GFR