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Physiology Exam 5 > Renal: structure, function, glomerular filtration > Flashcards

Renal: structure, function, glomerular filtration Flashcards

1
Q

describe the course of nephron

A

renal corpuscle > proximal tube > thin descending LH > thin ascending LH > thick ascending LH > distal convoluted tubule > connecting tubule > cortical collecting duct > medullary collecting duct > papillary duct

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2
Q

what are the 2 types of nephrons?

A
  1. cortical (85%)

2. juxtamedullary (15%)

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3
Q

what are sturctural differences of nephrons?

A

cortical – short LH & thick ascending LH mostly in the cortex

juxtamedullary – long LH & mainly in the medulla

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4
Q

what is the functional role of cortical and juxtamedullary?

A

cortical - tubular reasorption (removal of solutes and H2O

juxtamed - maintain osmotic gradient in medulla

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5
Q

trace blood flow through renal artery

A

renal artery > interlobar a.a. > arcuate a.a. > interlobular a.a. > afferent arterioles > glomeruli > efferent arteriols > peritubular capillarties or vesa recta

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6
Q

how many capillary beds are associated with renal vasculature?

A

cortical - perttubular nephrons (90% of blood flow)

juxtamed - vesa recta (10% of blood flow)

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7
Q

major functions of kidney

A
  • Regulate the volume of body water
  • Regulate the balance of inorganic ions
  • Regulate body pH
  • Excrete metabolic waste products & foreign substances
  • Produce hormones and enzymes
  • Help regulate blood pressure
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8
Q

what is approx. osmolartiy of body fluids?

A

300 mOsm

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9
Q

what are the inorganic ions in osmolarity?

A 
Na
K
Cl
H
HCO3
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10
Q

what metabolic waste is is excreted from by the kidney?

A

urea - nitrogen metab
uric acid - nucleic acid metab.
creatinine - creatinine phosphate
urobilinogen - Hb breakdown

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11
Q

what hormones are produced by the kidneys?

A 
erythropoietin (EPO)
Vitamin D3 (Calcitrol)
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12
Q

what enzyme is produced in the kidney?

A

Renin

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13
Q

what is EPO? when is produced?

A

a. protein that stimulates erythrocyte (RBC) production

b. when renal O2 pressure is low

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14
Q

what is calcitrol? what’s its function?

A

a. steroid

b. increase Ca and PO4 (phosphate) uptake in intestine

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15
Q

what is renin? What’s its function?

A

a. enzyme
b. hydrolyzes angiotensinogen to angiotensin 1 (Ang I). Ang I is converted to Ang II by angiotensin converting enzyme (ACE)
c. Renin increases arterial B/P

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16
Q

what is angiotensin?

A

peptide hormone that causes vasoconstriction

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17
Q

what causes H2O retention in kidney?

A

low MAP or blood volume > ADH/Vasopressin secretion > H2O retention

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18
Q

what causes an increase in MAP (in reference to kidneys)

A

low MAP or blood volume > Renin secrection > angiotensinogen conversion to Ang I > Ang I converted to Ang II (by ACE) > Vasoconstriction

19
Q

What causes Na retention in the kidney?

A

low MAP or blood volume > Renin secrection > angiotensinogen conversion to Ang I > Ang I converted to Ang II (by ACE) > aldosterone secrection > Na retention

20
Q

How is water ingestion triggered ?

A

thirst mechanism triggered by Ang II

21
Q

what structures make up the juxtaglomerular apparatus (JGA)? what arteriole is it associated with?

A

a. juxtaglomerular cells and macula densa of distal tubule

b. afferent arterial

22
Q

What structures compose the renal corpuscle?

A

bowman’s capsule (2 layers – parietal & visceral (podocyte - foot prosesses)
glomerular capillary

23
Q

What 3 glomerular filtration barriers?

A
  1. endothelial cells
  2. basil lamina
  3. epithelial cells (podocytes)
24
Q

What is true of endothelial cells?

A
  1. they are fenestrated
  2. plasm fluides freely permeate
  3. composed of pores
  4. part of the capillary lumen
25
Q

what is true of the basil lamina?

A
  1. negatively charged
  2. repels negativly charged proteins
  3. extracellular matrix
  4. located between endothelial and epithelial cells
26
Q

what is true of epithelial cells?

A
  1. a.k.a. podocytes
  2. octopus like structures
  3. compose filtration slits
  4. part of the lumen of bowan’s capsule
27
Q

how does glomerular filtration occur?

A

occurs due to the difference between a blood pressure in the capillaries and a pressure in Bowman’s space.

28
Q

which force favors filtration? opposes it?

A

a. favors - glomerular capillary pressure (Pgc) in mmHg

b. opposes - fluid pressure in Bowmans space (Pbs) and oncotic pressure ( ) (in mmHg)

29
Q

what causes oncotic pressure?

A

large proteins in the plasma

oncotic pressue is higher than the pressure in bowmans space

30
Q

calculate net glomerular filtration pressure

A

cut and paste pic

31
Q

what is renal blood flow rate?

A

1 L/min

20% of resting CO

32
Q

what is renal plasma flow rate?

A

625 mL/min (approx. 900 L/day)

33
Q

how much of the plasma gets filtered in Bowman’s capsule? what is this known as?

A

a. approx. 180 L/day @ 125 mL/min (20% of renal plasma flow) the rest passes through glomerular capillaries into efferent arterioles
b. GRR - glomerular filtration rate

34
Q

What is true of plasma filtration?

A
  1. 99% of filtered plasma is reabsorbed
  2. reabsorb approx 178-179 L/day
  3. excrete approx 1-2 L/day
  4. Plasma vol = 3 L
  5. filtered approx 60 times/day
35
Q

How is GFR controlled?

A

constriction of dilation of afferent or efferent arterioles

36
Q

how is the pressure between the arteries and capillaries in bowman’s space decreased ?

A
  1. constriction of afferent arteriole (increase resistance) OR dilation of efferent arteriole
  2. decreases glomerular capillary pressure (Gcp)
  3. decreases GFR
37
Q

How is the pressue between the arteries and capillaries in bowman’s space increased?

A
  1. Constriction of efferent arteriole OR dilation of afferent?
  2. increases (Gcp) “dam’s it up”
  3. increases GFR
38
Q

how to remember how GFR is decreased

A 
"C.A.D.E. decreases GFR"
Constricted 
Afferent arterioles
or 
Dilated 
Efferent arterioles

NOTE: increase GFR is C.E.D.A

39
Q

what are extrarenal requlators of afferent and efferent arterioles ?

A

neural inputs

hormones

40
Q

what are the intrarenal regulators of afferent and efferent arterioles?

A

a.k.a autoregulation (independent of neural and homonal input

41
Q

What are the mechanisms of intrarenal regulation?

A

myogenic

tubuloglomerular feedback

42
Q

Describe the myogenic mechanism

A

Smooth muscles of afferent arterioles are stretched in response to high blood pressure → Stretch-activated ion channels are activated, leading to muscle contraction → reduces the volume of blood → reduces Pgc. Conversely, muscle relax → raise Pgc

43
Q

Describe the tubuloglomerular feedback mechanism

A

Macula densa cells sense changes in luminal salt load → release paracrines → alter smooth muscle contraction in afferent arterioles → adjust Pgc

44
Q

what cells receive the neuronal and hormonal inputs ?

A

mesangial cells (smooth muscle cells that surround the glomerular capillaries

constriction of cells reduce surface area of capillaries

Physiology Exam 5 (7 decks)

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