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BIOL 432 > Urinary Anatomy > Flashcards

Urinary Anatomy Flashcards

1
Q

Where are the kidneys locate?

A

retroperitoneal
superior portion is protected by the 11th and 12th ribs

lie anterior to the quadratus lumborum and psoas major muscles
- QL - moves pelvis, deeper
- PM - moves thigh, more superficial

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2
Q

What do the pronephros, mesonephros, and metanephros do and what do they develop into?

A

pronephros - similar arrangement but does not filter blood
- disappears as mesonephros develops
- pronephric ducts connect to cloaca

mesonephros - where 1st filtration occurs
- mesonephric tubules grow and fuse with pronephric ducts
- branches from aorta grow into mesonephric tubules to form glomeruli

Metanephros - develops from mass of unorganized mesoderm
- metaneprhic diverticulum: develops into calyces and collecting ducts
- mesonephros + metanephros = nephron

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3
Q

What does the nephron develop from?

A

metanephrogenic blastema - becomes the nephrotic vessel that associates with glomerulus

metanephric diverticulum develops into calyces and collecting ducts

renal ducts develop into Bowman’s capsule, proximal convoluted tubule, loop of Henle, and distal convoluted tubule

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4
Q

Where is the best place to transplant a kidney?

A

R iliac fossa
- blood vessels are attaches to the external iliac and the ureter is shorter

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5
Q

What does the hilus in the kidney contain?

A

renal artery and vein
ureter

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6
Q

What does the renal sinus contain?

A

minor and major calyces
renal pelvis - where major calyces come together
adipose tissue in renal sinus

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7
Q

What is the difference between the juxtamedullary nephron and cortical nephron?

A

juxtamedullary - nephron that starts in the cortex and dips into the medulla

cortical - nephron that starts in the cortex but does not go into medulla

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8
Q

describe the blood flow from the renal artery to peritubular capillaries

A

renal after - segmental artery - interlobar artery - arcuate artery - interlobular artery (cortical radiate) - afferent arteriole - glomerulus - efferent arteriole - peritubular capillaries

when going back to veins, enters venules and descends via complementary structures starting with the interlobular veins besides segmental

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9
Q

What is cap bed 1 and cap bed 2 in the renal system?

A

Cap bed 1 - glomerulus
- blood from afferent arteriole

Cap bed 2 - peritubular capillaries
- blood from efferent arterioles
- important for secretion and reabsorption

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10
Q

There are two fates of the efferent arteriole. What are they and where are they located?

A

peritubular capillary - spans the cortex

vasa recta - if efferent arteriole is near the arcuate, it can drop into the medullary pyramids
- next to the juxtramedullary nephron

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11
Q

How do the arterioles, glomeruli affect pressure of the kidneys?

A

smooth muscles on afferent and efferent arterioles allow them to control blood pressure

no smooth muscle on glomeruli - requires pressure from the arterioles

to increase filtration pressure, efferent dilates
to decrease filtration pressure, efferent constricts

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12
Q

Describe the filtration membrane of the kidney. What is is made of? How do these structures filter the filtrate?

A

SSET sandwich made from parietal layer of Bowman’s capsule and glomerular capillaries

capillaries - contain fenestra that allow passage of small proteins ions, NO cells
- basal lamina layer from capillaries

reticular lamina - made from the epithelium of the capillary, thicker, in between basal laminas
- basement membrane with the basal and reticular lamina does most filtration

Bowman’s capsule - basal lamina layer that meets the reticular lamina
- contain PODOCYTES - cells that have PEDICELS that interdigitate
- pedicels form filtration slits
- filtration slits contain slit diaphragms - a small negative protein membrane that helps repels AA

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13
Q

Describe the proximal convoluted tubule. What kind of ET does it have? Describe its folding and how it helps its function

A

closest tubule to the Bowman’s capsule
- major site of water and solute reabsorption
- site of H ion and detoxified drug secretion

ET: simple cuboidal with microvilli that increases SA
- microvilli on filtrate side

contains lateral and basal infolding that helps increase surface area

contains lots of mitochondria at basal infolding
- close to peritubular capillaries for active transport

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14
Q

How can you tell the difference between the collecting duct and distal tubule histology?

A

both do not have microvilli (cancels proximal tubule)

distal tubule - nuclei tend to bulge near surface
- carries filtrate back towards glomerulus - straight tubule

collecting duct - nuclei towards bottom
- found in both cortex and medulla

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15
Q

What are the structures that are only found in the cortex?

A

blood vessels:
cortical radiate
afferent arteriole
efferent arteriole
glomerulus
peritubular capillaries

nephron/collecting duct:
Bowman’s capsule
proximal convoluted tubular
distal convoluted tubule

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16
Q

What are the structures that are found in the medulla only?

A

blood vessels
- interlobar arteries
- vasa recta

nerphon/collecting duct:
papillary ducts - located at tips of medullary period

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17
Q

What structures are i both the cortex and the medulla?

A

arcuate artery - in between, but no other vessel is shared

collecting ducts

nephron loops: long nerphon loops

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18
Q

What happens at these different points of the nephron: proximal convoluted tubule, nephrons loop, distal convoluted tubule, collecting ducts

A

proximal convoluted tubule - major site of water and solute reabsorption
- site of H+ and drug secretion

nephron loops - site of concentration gradient formation

distal convoluted tubules - site of REGULATED solute reabsorption

collecting ducts - site of REGULATED water reaborption

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19
Q

Where is the first place of filtrate? What structures are involved?

A

first place of filtrate - capsular space

structures - filtration membrane formed between:
- glomerular capillaries - no smooth muscle, crosses epithelium into glomerular capsule and into capsular space
- capsule - visceral layer of capsule is where filtration occurs, contains podocytes

20
Q

What are the structures in the filtration membrane that filter particles out of the filtrate?

A

visceral capsule later - podocytes
- pedicels interdigitate to make filtration slits
- slit diaphragm - nephrin - zipper appearance, podocin

fenestra of SSET - visceral capsule and glomerular capillaries
- 50-70 nm, small proteins can pass

basement membrane - visceral capsule and glomerular capillaries
- reticular lamina sandwiched between basal lamina
- where most filtration occurs via collagen fibers

general negative charges from: glycocalyx on capillary, basement membrane, slit diaphragm to prevent proteins from passing

21
Q

What are the pressures that determine filtration pressure? How does that affect glomerular filtration rate?

A

glomerular filtration rate - how much fluid moving across filtration membrane
- 100 mL blood = 1 mL fluid into nephron

determined by:
blood pressure from the afferent arteriole - into capsule

capillary osmotic pressure - colloid pressure
- albumin cannot cross, attracts water back into the arteriole
capillary hydrostatic pressure - capsule expands and resists additional fluid

22
Q

How does dilating/construction of the afferent and efferent arteriole affect GFR?

A

Afferent:
- dilation: increases volume = increase in hydrostatic pressure = increase in flow of fluid through nephron
- construction: reduces fluid flow, decreases hydrostatic P and flow of fluid through nephron

Efferent:
- dilation: more fluid out of glomeruli, less hydrostatic pressure lower filtration rate
- constriction increases hydrostatic pressure and increases filtration rate

23
Q

What is the myogenic response in renal blood flow?

A

when there is increased blood flow in the afferent arteriole, it stretches the tunica media (smooth muscle) in wall and causes it to contract
- protects glomerular capsule from hypertension
- does not require hormones/molecule/innervation

low blood flow - blood vessels collapse
- responds with vasodilation

24
Q

What are juxtaglomerular cells? Where are they located? What does it release?

A

specialized granular cells in the smooth muscle of the afferent arteriole
- baroreceptors - sensitive to low hydrostatic pressure and release renin
- sympathetic stimulation: sympathetic neurons release NE that bind to B1 receptors and cause renin to be released
- can be stimulated by prostaglandins released by macula densa cells

25
Q

What is the macula densa? Where is it located? What does it release?

A

macula densa - specialized cells in the in the distal tubule near the Bowman’s capsule
- chemoreceptors sensitive to low [Na] in filtrate
- triggers dilation of the afferent arteriole when Na in filtrate low

releases:
- prostaglandins - in response to low Na in filtrate (low BP), stimulates renin release
- adenosine - in response to high Na (high BP) - causes afferent arterioles to constrict, also stops renin release

26
Q

What is int he juxtaglomerular capsule? What are the extraglomerular meseangeal cells? Where are the located?

A

juxtaglomerular cells, macula densa, extraglomerular mesangial cells

located between the afferent and efferent arterioles in the juxtaglomerular capsule
- type of smooth muscles cells involved in auto regulation of GFR

27
Q

What are the intraglomerular mesangial cells? How do they regulate filtration rate?

A

modified smooth muscle cells that are wrapped on the outside of podocytes
- when they contract the decrease the surface area of the basement membrane and DECREASE filtration rate
- does not effect glomerular pressure

28
Q

Describe the MOA for renin.

A

renin - enzyme made by juxtaglomerular cells in kidney

angiotensinogen - protein made by liver
- gets converted into angiotensin I by renin

angiotensin I goes to lungs and angiotensin converting enzyme (ACE, made in lungs) converts AGI into AGII

angiotensin II effects:
- efferent arterioles constrict
- renal glands to secrete aldosterone for Na/H2O retention
CNS effects:
- increases thirst to increase blood volume
- stimulates ADH secretion - water reabsorption
- sympathetic stimulation - increased cardiac output and vasoconstriction

29
Q

How does atrial naturietic peptide and brain naturietic peptide affect afferent arteriole hydrostatic pressure?

A

increases afferent arteriole hydrostatic pressure
- stretching of atria of heart and ventricles of the brain

ANP/BNP cause:
- dilation of the afferent arterioles
- constriction of the efferent arterioles
- increased Na reabsorption by proximal (1*) and distal tubules

30
Q

Where does reabsorption occur? What kind of cells does this structure have? What features of this cell help its function?

A

reabsorption occurs at the proximal convoluted tubule

simple cuboidal cells with tall microvilli
- contains basal and lateral infolding for increased surface area
- contains lots of mitochondria on the basal surface for active transport
- basal membrane against peritubular capillary, apical surface facing filtrate

31
Q

Describe how glucose and amino acidsreabsorption occurs. What kind of transport does it require?

A

crossing apical membrane of PCT
- secondary active transport with Na into the cell

crossing basal membrane of the PCT
- glucose transporter - facilitated diffusion
- AA transporter - fascinated diffusion

Na/K active transport pumps (basal membrane) remove and create an Na gradient that allows symptort movement of other molecules with Na
- important for reabsorption of glucose, AA, K, Cl, HCO3-

32
Q

How does K affect reabsorption?

A

K pumped into the cell via Na/K pumps
K simply diffuses out of leak channel

helps create Na gradient needed for secondary active transport for reabsorption

32
Q

How does water and urea leave the filtrate?

A

water - moves through aquaporins depending on concentration gradient

urea - leaves filtrate and is soluble in plasma membrane

33
Q

What is secretion in the PCT? What gets secreted?

A

peritubular capillary to filtrate

  • urea, uric acid, bile acids, catecholamines, some creatinine
  • drugs

PCT can only SECRETE H and can only REABSORB HCO3-

34
Q

What happens to glutamine when it is in the PCT tubule cells?

A

enters cuboidal cell and gets deaminated, oxidized and acidified to create:
NH4 (ammonia): added to filtrate
HCO3-: returns to capillary via secondary active transport

35
Q

Describe the thin segment of the descending limb and ascending limb of the nephron loop. What are these areas permeable to and what kind of ET do they have?

A

BOTH have simple squamous

descending loop: highly permeable to WATER

ascending loop: impermeable to water
- moderate permeability of urea and sodium

36
Q

Describe the thick segment of the ascending limb. What role does it play in creation of the extracellular osmotic gradient?

A

simple cuboidal ET
- impermeable to H2O, urea

contains active transport pumps for Na

pumps Na out of loop and into extracellular space, but does not pump water out with it
- creates a 200 mosm/liter gradient
- ascending limb becomes hypotonic
- extracellular fluid is hypertonic - causes water to leak out of descending loop

continuous cycle to increase osmolality of extracellular and descending loop

37
Q

How does the vasa recta relate to the nephron loop and how does it contribute to the cellular osmotic gradient?

A

Vasa recta - has ascending and descending loop similar to loop of henle
- blood in vasa recta flows in opposite direction

descending limb - absorbs solutes
ascending limb - absorbs water

instead of water from the descending limb going into the extracellular space, it goes into the vasa recta and allows the gradient to continue forming

38
Q

Compare the osmolality of the descending limb and the ascending limb of the loop of henle

A

descending limb: 200 mosm/L more than ascending limb
- hyper osmotic
- water being pumped out increases concentration of solutes in limb

ascending limb - hypo osmotic
- filtrate leaving ascending limb to distal tubule becomes less concentrated

39
Q

Once the filtrate reaches the collecting duct, what happens? What is the osmolality of the filtrate?

A

osmolality of filtrate as it enters the collecting duct is 100 mosm/L

can continue into calyces as is

if body needs to increase blood volume, ADH is released
- causes aquaporins to be inserted into the wall of the collecting duct
- water moves out into the of the collecting duct and into intracellular space until concentration matches extracellular fluid

40
Q

Describe the effects of the following hormones and where they affect reabsorption: aldosterone, ADH, parathyroid hormone, calcitriol

A

aldosterone: mostly DCT, some collecting duct
- increases synthesis of Na transport proteins in the cell for reabsorption

ADH - collecting duct
- adds aquaporins to the membrane for water reabsorption

parathyroid hormone: increases Ca absorption
- receptors found in DTC

calcirtiol - synthesized by kidneys to increase Ca reabsorption in kidneys and small intestine

41
Q

What are principle cells? Where are they located? What are they sensitive to? When these hormones bind, what happens?

A

found in the DCT and the collecting duct
- contain receptors for aldosterone and ADH

when bound, increases synthesis of:
- NaK pumps for NaCl reabsorption: Na pumped out into peritubular, more Na in through apical membrane leak channels
- aquaporins for water reabsorption

42
Q

Describe aldosterone release. What regulates it?

A

angiotensin II stimulates release of aldosterone from the adrenal cortex - made from cholesterol

juxtaglomerular cells release renin in response to:
- drop in BP - sympathetic NS releases NE, binds B1 to release renin
- drop in BP - less stretch in afferent arteriole - stimulates release
- decrease in Na in distal tubule filtrate triggers macula densa to release prostaglandins - release renin

43
Q

Describe how aldosterone gets into the cell. How does it make more Na channels?

A

aldosterone - cholesterol derivative - can pass through membrane
- receptor in cytoplasm: moves into the nucleus to stimulate transcription of genes to make more Na, K channels and Na/K pump

mostly occurs in the distal convoluted tubules

allows Na to move first and water follows

44
Q

Describe intercalated cells A and B. Where are they found?

A

alpha cells: distal convoluted tubule and collecting duct
- secrete H
- reabsorb HCO3-

beta cells: distal convoluted tubule
- reabsorb H
- secrete HCO3-

BIOL 432 (25 decks)

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