The renal system

Question 1

what is the function of the renal system?

Answer 1

excretion of waste
regulate H2O and electrolyte balance
hormones

Question 2

what are the functions of the kidneys?

Answer 2

regulation of water, inorganic ion balance
removal of metabolic waste from blood
removal of foreign chemicals in blood via excretion in urine
gluconeogenesis - produce glucose during prolonged fasting
production of hormones/enzymes

Question 3

describe the structure of the kidneys

Answer 3

renal medulla
renal cortex
nephron
renal pelvis
ureter- to urinary bladder

Question 4

what are nephrons?

Answer 4

structural and functional units of kidneys, each nephron consists of a renal corpuscle and a renal tubercle

Question 5

what do each renal corpuscle of nephrons contain?

Answer 5

a glomerulus and a bowman’s capsule surrounding the glomerulus

Question 6

what is the structure of the kidney and urinary system?

Answer 6

glomerulus
bowmans capsule
tubule extends from BC and subdivides into proximal convoluted tubule,
loop of henle,
distal convoluted tubule
collecting- duct system

Question 7

what occurs at the the level of the conducting-ducts?

Answer 7

multiple tubules join and empty into the renal pelvis from which urine flows through the ureters to the bladder

Question 8

what supplies the glomerulus with blood?

Answer 8

an afferent arteriole and an efferent arteriole which leaves the glomerulus to branch into peritubular capillaries which supply the tubule

Question 9

what are juxtaglomerular cells?

Answer 9

mechanoreceptors that sense BP in the afferent arteriole

Question 10

what are mascula densa cells?

Answer 10

chemoreceptors that respond to changes in the NaCl content of the filtrate

Question 11

what makes up the juxtaglomerular apparatus?

Answer 11

juxtaglomerular cells
mascula densa cells

Question 12

what substances get filtered by the kidneys?

Answer 12

Na+
glucose
amino acids
small molecules

Question 13

what substances don’t get filtered by the kidneys?

Answer 13

large molecules
RBC
large proteins

Question 14

what substances don’t get filtered by the kidneys?

Answer 14

large molecules
RBC
large proteins

Question 15

what are the 3 basic renal processes?

Answer 15

glomerular filtration GFR
tubular secretion
tubular reabsorption

Question 16

what drives glomerular filtration and what opposes it?

Answer 16

hydrostatic pressure in the glomerular capillaries drives GFR
hydrostatic pressure in bowman’s capsule and the osmotic force due to the proteins in the glomerular capillary plasma oppose GFR.

Question 17

the excretion of a substance is equal to what?

Answer 17

the amount of substance filtered (GRF) plus the amount secreted (by tubular secretion) - the amount reabsorbed (tubular reabsorption)

Question 18

which substances get excreted immediately in urine and which are reabsorbed ?

Answer 18

foreign substances get completely excreted in urine
substances important to retain but require maintenance within a homeostatic range get reabsorbed and excreted
very importance substances for health get completely reabsorbed

Question 19

amount excreted =

Answer 19

amount filtered + amount secreted - amount reabsorbed

Question 20

what is glomerular filtration?

Answer 20

the amount of blood filtered by the glomeruli each minute

Question 21

what factors influence GRF ?

Answer 21

capillary permeability
SA of capillary bed
hydrostatic pressure driving fluid out capillaries
osmotic forces which oppose exit of fluid

Question 22

NET filtration pressure =

Answer 22

transcapillary pressure gradient - colloid pressure gradient

Question 23

how are the kidney glomeruli a more efficient filter than other capillary beds?

Answer 23

filtration membrane is a large SA, very permeable to H2O and solutes
glomerular pressure is higher so they produce more L/day than other capillary beds

Question 24

what is tubular secretion important for?

Answer 24

disposing of drugs and drug metabolites
eliminating undesired substances
removing excess K+
controlling blood pH

Question 25

where does the majority of the reabsorption take place?

Answer 25

proximal convoluted tubule and loop of Henle

Question 26

what is renal clearance?

Answer 26

the amount of a substance filtered per min ( or mass of the substance excreted) / by its plasma concentration of the substance
RC = (U x V)/ P
U= conc of substance in urine
V= flow rate of urine formation
P= conc of substance in plasma

Question 27

how is GFR measured experimentally and estimated clinically?

Answer 27

experimentally by means of insulin clearance and estimated clinically by means of the creatine clearance

Question 28

what is filtration fraction?

Answer 28

the proportion of the plasma that enters the kidneys that is subsequently filtered at the glomerulus and passes into the renal tubules

Question 29

how is filtration fraction calculated?

Answer 29

GFR/ renal plasma flow (RPF)
typically its- 0.16-0.20