structure and function of the kidney I

Question 1

kidney location

Answer 1

just below the liver
posteriorly
protected partially by ribs
adrenal gland on top of each kidney, endocrine function

Question 2

Vascular supply to the kidneys

Answer 2

renal artery/vein
aorta branches into renal artery which delivers blood
renal vein carries blood kidney to vena cava

Question 3

Hilum

Answer 3

opening for attachment of vasculature (renal artery and vein)
Hilum opens into central cavity known as renal sinus

Question 4

kidney function

Answer 4

filtration and modification of fluids
regulate water and electrolyte balance
Remove waste products eg urea and eliminate them in the urine

Question 5

urinary tract

Answer 5

transportation/storage of urine

Question 6

renal fascia

Answer 6

connective tissue anchor

Question 7

adipose capsule

Answer 7

support and shock

Between renal capsule and renal fascia (fascia outermost)

Question 8

renal capsule

Answer 8

connective tissue/ tough fibrous layer surrounding the kidney and covered in a layer of fat known as the adipose capsule of kidney.

Question 9

path of urine drainage

Answer 9

collecting duct
papillary duct in renal pyramid
minor calyx (funnel)
major calyx
renal pelvis
ureter
urinary bladder

Question 10

path of blood flow

Answer 10

renal artery
segmental arteries
interlobar arteries
afferent arterioles (very small, in contact with nephron)
glomerular capillaries
efferent arterioles
peritubular capillaries
various veins (incl interlobular)
renal vein

Question 11

Bowman’s capsule

Answer 11

site of filtration
has 2 layers- inner (visceral-associated with an organ) epithelium and paretial, outer epithelium
inner is covered with podocytes

Question 12

Proximal tubule

Answer 12

tubule closest to bowman’s in a network of tubules

Question 13

cortex

Answer 13

all bowman’s capsules, proximal and distal tubules

outer region of kidney

Question 14

medulla

Answer 14

loops of henle and collecting ducts

inner region of kidney

Question 15

juxtamedullary nephron

Answer 15

next to medulla
capillaries here are called vasa recta
make up 15% of nephrons

Question 16

proximal tubule structure

Answer 16

convoluted
simple cuboidal epithelium with microvilli
brush border provides large SA for processes (reabsorption)
and lots of mitochondria for active processes

Question 17

descending limb of loop of henle

Answer 17

thin

flattened simple squamous epithelium

Question 18

ascending limb

Answer 18

thick

simple cuboidal epitheium with no microvilli

Question 19

cuboidal epithelium

Answer 19

specialised for diffusion

Question 20

renal corpuscle

Answer 20

site of filtration

bowman’s capsule + glomerulus

Question 21

3 filtration barriers between glomerulus capillaries and bowman’s capsule lumen

Answer 21

Fenestrated capillaries- large gaps between endothelial cells (but not big enough for cells to pass through, allow all components of blood plasma to pass)
Basal lamina- thin layer of ECM, between endothelial cells and podocytes, acts as a big sieve- prevents filtration of larger proteins
Podocytes are narrow filtration slits- finest level of filtration- prevents filtration of medium sized proteins.
Filtered material moves across these barriers into the lumen of the bowman’s capsule

Question 22

glomerular filtrate

Answer 22

ultrafiltrate
contains water and dissolved solutes (water and electrolytes, glucose, AAs, waste prducts, urea), only trace amounts of protein (small), ions

Question 23

filtration fraction

Answer 23

20% amount of substance filtered from plasma into capsule (20% of total renal blood flow)

Question 24

What drives filtration

Answer 24

hydrostatic pressure of glomerular capillaries (Ph) ie pressure exerted on the wall of the vessel

Question 25

What is the hydrostatic pressure opposed by

Answer 25

Pfluid: hydrostatic pressure of fluid in the bowman's capsule Pi: colloid or oncotic pressure of plasma proteins

Question 26

How to work out net filtration pressure

Answer 26

Ph - Pi - Pfluid

Question 27

Glomerular filtration rate

Answer 27

volume of filtrate produced by the kidneys per minute

Question 28

Despite a net filtration pressure of only 10 mmHg, volume of filtrate is large because:

Answer 28

SA of capillaries large Glomerular capillary endothelium is fenestrated Glomerular capillary BP is high

Question 29

If there is increased resistance in the afferent arteriole

Answer 29

there is incr blood flow to other organs and decr RBF Decreased GFR

Question 30

If there is increased resistance in the efferent arteriole

Answer 30

Decreased RBF, increased Ph and GFR

Question 31

amount of solute excreted =

Answer 31

amount filtered - amount reabsorbed + amount secreted from blood

Question 32

What proportion of fluid and solutes are reabsorbed in the proximal convoluted tubule

Answer 32

65%

Question 33

proximal tubule reabsorption and secretion

Answer 33

lots of reabsorption, some secretion | osmorality same at end of proximal tubule

Question 34

ureter

Answer 34

transports urine formed in the kidney to the bladder for storage prior to secretion

Question 35

where are nephrons located

Answer 35

mostly in the cortex, but some extend into the medulla

Question 36

5 regions of the nephron overview

Answer 36

1. renal corpuscle filters blood 2. proximal tubule reabsorbs electrolytes, nutrients and water. 2/3 of electrolytes and water filtered from the blood returned 3. Loop of Henle creates osmotic gradient by reabsorbing water and electrolytes differentially along its length- gradient allows kidney to concentrate urine. 4. Distal tubule reabsorbs electrolytes and water (under hormonal control) 5. collecting duct, more water reabsorbed (hormonal control)

Question 37

filtrate that exits proximal tubule

Answer 37

high in wastes, low in nutrients, greatly reduced in volume

Question 38

More detail of loop of henle osmotic gradient

Answer 38

Osmolarity of filtrate inside loop low in cortex and high in the medulla water lost by osmosis as it moves from low solute conc in tubule into higher solute conc in surrounding tissue. More concentrated as flows deeper into medulla, then solutes move out passively as fluid rounds bend, then in ascending limb ions pumped out so becomes less concentrated

Question 39

distal tubule cell types

Answer 39

simple cuboidal epithelium with little microvilli