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GU1 - Nephrology > Phys 1 > Flashcards

Phys 1 Flashcards

1
Q

how many nephrons in a kidney?

A

1 million

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2
Q

What are the 4 main functions of the nephron (aka blood processing unit)

A
  1. filtration
  2. reabsorption
  3. secretion
  4. excretion
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3
Q

functions of the kidney (there are a ton)

A
  • filter plasma and produce urine
  • excrete metabolic waste products
  • reabsorb glucose and amino acids from filtrate
  • regulate Ca and phosphate uptake
  • regulate water homeostasis
  • regulate extracellular vol. –> BP
  • regulate electrolytes
  • acid base homeostasis
  • gluconeogenesis
  • endocrine function
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4
Q

what are the endocrine components of the kidney? (4)

A
  • kinins
  • 1, 25-dihydroxycholecalciferol
  • EPO
  • renin
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5
Q

What 2 diseases cause the largest prevalence of kidney dysfunction?

A
  1. DM

2. HTN

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6
Q

What type of endothelium is found within the glomerulus?

A

fenestrated

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7
Q

characteristics of the afferent arteriole that feeds the glomerulus

A
  • high resistance vessel
  • high pressure
  • larger diameter than efferent
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8
Q

what is the general function of the afferent arteriole?

A

to force fluid and solutes from the circulation to the glomerulus to form filtrate

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9
Q

mesangial cells

  • where
  • function
A
  • between capillaries

- contractile cells that regulate the filtration rate and restrict large particles

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10
Q

What is the glomerular capsule aka bowman’s capsule?

A
  • a blind sac of the nephron
  • surrounds the glomerulus
  • receives filtrate
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11
Q

podocytes

A
  • cells that surround the capillaries

- they have foot like extensions that function as pores for another layer of filtration

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12
Q

PCT cell type

A

cuboidal

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13
Q

characteristics of the PCT

A
  • high in mitochondria (think active transport occurring here)
  • dense w/ microvilli
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14
Q

what mainly occurs at the PCT?

A

-active reabsorption of water and solutes (glc) from the filtrate

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15
Q

descending limb of the LoH

A
  • thin
  • squamous epithelium
  • permeable to water
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16
Q

ascending lib of the LoH

A
  • thick
  • cuboidal epithelium
  • solute secretion (i.e Na)
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17
Q

What are the 2 types of nephrons?

A
  1. cortical nephrons

2. jextamedullary nephrons

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18
Q

cortical nephrons

A
  • make up 85% of nephrons

- short loops

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19
Q

juxtamedullary nephrons

A
  • 15% (even though this is what we talk about the most)
  • long loops
  • have vasa recta
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20
Q

characteristics of the DCT

A
  • cuboidal cells
  • lack microvilli (b/c not as much reabsorption occurring)
  • empty to collecting duct
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21
Q

peritubular capillaries arise from what?

A

the efferent arteriole

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22
Q

function and characteristics of the peritubular capillaries

A
  • surround the renal tubule
  • low pressure and porous
  • readily absorb water and solutes
  • return fluid to the renal vein
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23
Q

2 renal capillary beds

-function

A
  1. glomerulus
    - produces filtrate
  2. peritubular capillaries
    - reabsorbs most of the filtrate
24
Q

What is the point of contact between the DCT and the afferent arteriole?

A

juxtaglomerular apparatus

25
Q

what are the 2 cell populations that make up the juxtaglomerular apparatus?

A
  • juxtaglomerular cells

- macula densa

26
Q

the juxtaglomerular apparatus functions to regulate what?

A
  • blood volume
  • BP
  • GFR
27
Q

juxtaglomerular cells (aka granular cells)

  • where
  • function
A
  • in the afferent artery wall

- enlarged smooth muscle cells that function to produce and store renin in granules

28
Q

juxtaglomerular cells sense what?

A

low BP

29
Q

what juxtaglomerular cells release renin in response to low BP, what is the effect?

A
  • vasconstriction (systemic)

- increases blood vol. which therefore increases BP

30
Q

where is the macula densa located?

A

in the distal tubule

31
Q

the macula densa is sensitive to what?

A

NaCl concentration in the late ascending limb

32
Q

What is the outcome when the macula densa senses a decrease in NaCl concentration?

A
  • vasodilation of afferent arteriole: this increases GFR

- increase in renin release: increases blood vol. and pressure

33
Q

what coalesce to form the collecting ducts?

A

DCTs

34
Q

The epithelium of the collecting ducts consist of what 2 cell types?

A
  1. principal cells (P cells)

2. intercalated cells (I cells)

35
Q

principal cells of the collecting ducts function

A
  • Na reabsorption

- H2O reabsorption in response to vasopressin

36
Q

intercalated cells of the collecting ducts function

A
  • acid secretion

- HCO3 transport

37
Q

which cells have more microvilli and mitochondria, P or I?

A

I cells

38
Q

vasopressin effect at the collecting duct

A

it opens pores creating an aquaporin to allow for a lot of water absorption

39
Q

renal medullary interstitial cells (RMIC)

  • where
  • cell type
A
  • in kidney interstitial tissue

- specialized fibroblast like cells

40
Q

RMICs produce what (2)

A
  1. COX-2
    - PG
    - PGI2
  2. Prostaglandin synthase (PGES)
    - PGE2
41
Q

what effect does the COX2 produced by the RIMCs have?

A

vasodilation and anti-coagulation

42
Q

what effect does the PGES produced by the RIMCs have?

A

vasodilation

43
Q

how much blood to the kidneys receive at rest?

A
  • 1.2-1.3 L/min
  • just under 25% of the CO
  • under close systemic and intrinsic control
44
Q

pressure throughout the system

  • systemic
  • glomerular
  • peritubular
  • renal vein
A
  • mean systemic arterial pressure: 100 mm Hg
  • glomerular capillary P: 45 mm Hg
  • peritubular capillaries: 8 mm Hg
  • renal vein P: 4 mm Hg
45
Q

comparing glomerular capillary pressure to systemic arterial pressure

A

glomerular P is about 40% of the systemic arterial pressure

46
Q

innervation of the kidney

A

SNS via the thoracic and lumbar sympathetic trunk

47
Q

innervation of the adrenal glands

A

thoracic sympathetic trunk

48
Q

What is the effect of the SNS on renal circulation in times of stress?

A
  • stimulation of adrenal medulla –> release of NE
  • beta 1 adrenergic receptors:
  • juxtaglomerular cells release renin
  • renal tubular cells reabsorb water and Na
  • alpha-1 receptors:
  • vasocontrict the arterioles
49
Q

what mechanism is responsible for autoregulation of renal blood flow?

A
  • myogenic mechanism

- vascular smooth muscle tends to contract when stretched

50
Q

how does the myogenic autoregulation mechanism work?

A

when BP increases, the afferent arteriole constricts to reduce the glomerular pressure

51
Q

what makes up the tubuloglomerular feedback mechanism?

A

the macula densa cells of the JGA of the DCT

52
Q

what does the tubuloglomerular feedback mechanism respond to?

A
  • increased osmolality and flow
  • this causes vasocontriction
  • therefore slowing GFR and increasing processing time

(and vice versa)

53
Q

EPO

  • what
  • prodcued by
  • in response to
A
  • protein hormone
  • produced mainly by kidney interstiital cells (but also liver)
  • in response to hypoxia
54
Q

function of EPO

A
  • circulates in response to hypoxia
  • binds receptors on proeyrthroblasts in BM
  • increases the production and maturation of RBCs
55
Q

calcitriol

  • aka
  • what
  • produced by
A
  • aka 1,25 dihydroxyvitamin D3
  • active form of vit. D
  • produced by the kidney
56
Q

calcitriol is produced in response to what?

A

PTH (increase in blood Ca)

57
Q

what is the action of calcitriol?

  • kidneys
  • GI
  • bone marrow
A
  • kidneys: increase tubular reabsorption of Ca
  • GI: increase absorption of Ca
  • bone: release Ca from bone

GU1 - Nephrology (16 decks)

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