kidney structure & function

Question 1

what is the function of the kidneys?

Answer 1

excretory organs

process blood and rid the body of the waste products of metabolism via urine

Question 2

what do the kidneys maintain the internal homeostasis of?

Answer 2

fluid & electrolytes-bp
acid/base
calcium/vit. D metabolism
erythropoietin

Question 3

what is the basic anatomy of the urinary system?

Answer 3

2 kidneys-produce urine
ureters-convey urine
bladder-store
urethra-void urine

Question 4

what is the cortex?

Answer 4

contains 85% of all kidney tubules-nephrons

Question 5

what are the 3 distinct parts of the kidney (macroscopic)

Answer 5

cortex, medulla, pelvis

Question 6

what is the medulla?

Answer 6

site urine is concentrated

prevents excess water loss

Question 7

what is the pelvis?

Answer 7

collection area for urine which is funnelled into the ureter

Question 8

describe the bv of the kidney

Answer 8

highly vascular
renal artery delivers blood from abdominal aorta
process 1.2L per min

Question 9

what are the bv of the kidney?

Answer 9

interlobular arteries
afferent arterioles
glomerular capillaries
-glomerulus
efferent arterioles
peritubular capillaries
-vasa recta
interlobular veins

Question 10

what is the nephron?

Answer 10

basic functional unit
filters blood plasma
excrete waste prod. of metabolism in urine
-cortical nephrons
-juxtamedullary nephrons

Question 11

what are the components of a nephron?

Answer 11

glomerulus
bowman's capsule
proximal convoluted tubule
loop of henle
distal convoluted tubule
collecting duct

Question 12

what is the renal corpuscle?

Answer 12

filtration

glomerulus & bowman’s capsule

Question 13

what is the renal tubule?

Answer 13

reabsorption and secretion
proximal convoluted tubule
loop of henle
distal convoluted tubule
collecting duct

Question 14

what is the glomerulus?

Answer 14

network of fine capillaries
single layer endothelial cells resting on basement membrane
fenestrated
enables rapid filtration of blood plasma
surrounded by bowman's capsule

Question 15

what is bowman’s capsule?

Answer 15

cuplike structure surrounding glomerulus
bowman’s space-in between layers
parietal-outer-layer
visceral-inner-layer comprised of specialised epithelium - podocytes

Question 16

how is the filtration barrier formed?

Answer 16

long branched processes (pedicels) of podocytes wrap around glomerular capillaries
glomerular endothelium, basement membrane and pedicels form filtration barrier

Question 17

what can move through the filtration barrier?

Answer 17

water and small molecules

not large proteins or cells

Question 18

what determines which molecules are filtered through the filtration barrier?

Answer 18

size and charge of filtration

Question 19

what are the 3 steps of glomerular filtration?

Answer 19

1. unfiltered blood arrives at glomerulus via afferent arteriole
2. blood components filtered though filtration barried
3. filtered blood exits glomerulus via efferent arteriole

Question 20

what is hydrostatic pressure?

Answer 20

filtration facilitated by pressure gradient

afferent has wider diameter- so blood arrives faster than can leave

Question 21

what is filtered?

Answer 21

water, glucose, amino acids, urea, creatinine, sodium, chloride, calcium, phosphate, potassium, bicarbonate

Question 22

what is not filtered?

Answer 22

cells, large proteins eg. haemoglobin, negatively charged proteins eg. albumin

Question 23

what is glomerular filtration rate? (GFR)

Answer 23

the rate at which blood is filtered through the glomerulus into the bowman’s capsule
healthy =125ml/min

Question 24

how is GFR mediated?

Answer 24

driven by glomerular hydrostatic pressure

counteracted by hydrostatic pressure in the bowman’s capsule & glomerular osmotic pressure

Question 25

what is GFR influenced by?

Answer 25

hydrostatic pressure
osmotic pressure
systemic bp
renin-angiotensin system
disease

Question 26

how does GFR effect kidney function?

Answer 26

kidney damage reduces GFR
reduced GFR=inefficient blood clearance and waste removal
waste pro. accumulate in blood
serum creatinine (&urea) measurements used to estimate GFR