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PHSI 208 > Renal 1 > Flashcards

Renal 1 Flashcards

1
Q

how much of CO do the kidneys together receive?

A

20%

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2
Q

what are the 3 main sections of the kidney?

A

cortex, medulla, pelvis

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3
Q

describe what the medulla contains

A

cone-shaped structures–>renal pyramids; renal columns in between the renal pyramids;–>tips of the renal pyramids for renal papillae–>extend into minor calyx; each kidney contains 8-20 minor calyces which form major calyx–>2-3 per kidney–> form chamber known as the renal pelvin, which then form the ureter–>

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4
Q

compair cortical and juxtamedullary nephrons?

A

cort: 80-85% of the nephron content, and the loop of henle does not extend deep into the medulla
jm: 15-20% of the total nephron content, has long loops of henle that extend deep into medulla;–>contain vasa recta circulation

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5
Q

what are the two components to a nephron?

A

tubular and vascular

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6
Q

describe the function and the parts of the vascular component

A

2 functions: nourishing the kidneys and taking part in the filtraton process in the kidneys;
contains 5 parts per each vascular component:
1. Afferent arteriole
2. glomerulus (first capillary bed)
3. Efferent artierole
4. second capillary network
5. venules

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7
Q

what is the function of the afferent arteriole in the nephron?

A

supplies blood to a single nephron ia the glom inside the renal corpuscle;

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8
Q

describe the glomerulus

A

located i nthe bowman’s capsule; surrounded by interlocking podocytes, where blood plasma passes through–>generates “protein-free plasma”–>drains into proximal tubule

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9
Q

describe the layers of the bowman’s capsule

A

parietal and visceral
parietal–> corpuscule cell layer;
visceral–> podocytes surrounding the capillaries of the glom;

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10
Q

what forms the kidney filtration membrane?

A

Podocytes, basement membrane of the visceral layer, and capillary endothelium

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11
Q

describe the efferent arteriole

A

drains blood away from the glom, as in, blood not filtered into bowman’s capsule

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12
Q

describe the second capillary bed?

A

originates from efferent arteriole; supplies blood to renal tissues for nourishment and involves exchange between the vasculature and tubular system, distal to renal corpuscle;Responsible for the conversion of the filtered fluid into urine

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13
Q

describe the capillary networks in the second capillary bed

A

peritubular capillaries–surrounds proximal and distal tubules in the cortex;
vasa recta–from the eff arteriole in the jm nephron–>surrounds loop of henle, descending deep into the medulla

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14
Q

describe the venules

A

blood from the second cap bed (peritub and vasa recta) drain into venules–>into the renal vein–>exits kidney–>flows into inferior vena cava–>back to heart

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15
Q

what composes the tubular element of the nephron?

A
  1. renal corpuscule
  2. proximal tubule
  3. loop of henle
  4. distal tubules
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16
Q

what is the renal corpuscule?

A

contains bowman’s capsule and glom; it is the filtration unit;

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17
Q

what is the prox tub?

A

contain prox convoluted tubule and straight tubule; the straight portion is aka pars recta, where bulk reabsorption (65-70%) of filtrate occurs;

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18
Q

describe the loop of henle

A

aka nephronic loops;
consists of descending and ascending branch; embedded into medulla;
–thin part of descending limb = permeable to water only–always hyperosm. fluid
–ascending limb = permeable to solutes only–always hypoosm fluid

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19
Q

describe the role distal tubules?

A

responsible for the fine-tuning of salt and water balance under the control of various hormones–Na, K, and Cl

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20
Q

describe the role collecting duct

A

all filtrate empties into this; also fine-tunes salt and water balance–>under control of various hormones as well (ADH, and aldosterone);
NA, K, and Cl are ACTIVELY reabsorbed

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21
Q

what is urine?

A

the fluid that leaves the collecting duct, and the fluid that cannot have its composition altered

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22
Q

what are the fluid compartments of the body?

A

ICF (2/3); ECF (1/3)–> 80% of ECF are interstitial fluids, and ~20% is plasma; minor compartments of ECF are the lymphatic system, bone, fluid within joints, digestive secretions, intraocular fluids, cerebrospinal fluids, sweat, etc

23
Q

Intracellular fluid is rich in K+, whereas the extracellular fluid is rich in Na+ and Cl-

A

ye

24
Q

how is water inputted into the body?

A

90% via drinking and food; 10% via metabolism

25
Q

how is water lost fro mthe body?

A

urine; fecal; insensible–evaporation; sweat, pathological– bleeding, vomitting, diarrhea, etc

26
Q

functions of the kidney?

A

1) To maintain H2O balance in the body
2) To regulate the quantity and concentration of most extracellular ions
e. g.) Na+, Cl-, K+, HCO3-, Ca++, H+, etc.
3) To maintain blood pressure and volume
4) To maintain proper acid-base balance
5) To maintain osmolarity
6) To excrete waste products of bodily metabolism
7) To excrete foreign compounds
8) To secrete erythropoietin
9) to secrete renin
10) to convert vit D to its active form

27
Q

how does the kidney function to maintain blood pressure and volume?

A
  1. low BP–>causes secretion of renin;
    Renin converts angiotensinogen into angiotensin I (ANG I), and ANG I to ANG II by ACE (Angiotensin Converting Enzyme)
  2. Blood volume is controlled through the kidney’s regulatory role in salt and H2O balance
28
Q

how does the kidney function to maintain the proper acid-base balance

A

by adjusting urinary output of H and HCO3

29
Q

how does the kidney function to maintain osmolarity?

A

controls the concentration of the solutes e.g.) Na+

30
Q

what is the function of excreting EPO?

A

released in response to low pp of O2–>stimulates RBC production

31
Q

how does the kidney convert vit D to its active form, and why is this important?

A 
The biologically active form of vit. D is also know as calcitriol (1,25-OH-vit.D)
 Parathyroid hormone (PTH) stimulates the kidneys to synthesize calcitriol
 by hydroxylation of 25-OH-vit. D into 1,25-OH-vit.D
 Calcitriol stimulates the gastrointestinal tract to increase the reabsorption of Ca++, thus elevating the blood level of Ca++--> need active vit D to increase blood levels of Ca
32
Q

what is the glom membrane composed of?

A

i) Glomerular capillary wall
ii) Basement membrane
iii) Inner layer of Bowman’s capsule

33
Q

descrbe the glom cap wall

A

single layer of endothelial cells with pores (fenestrae); 100x more permeable to H2O and solutes than capillaries elsewhere in the body

34
Q

describe the basement membrane of glom

A

Composed of collagen and glycoproteins (heparan sulfate proteoglycans)
Collagen provides structural strength
Glycoproteins discourage the filtration of smaller proteins in plasma

35
Q

describe the visceral layer of the BC

A

Consists of podocytes with
elongated foot processes
Interdigitate with foot processes of adjacent podocytes
Forms narrow slits between adjacent foot processes which are known as filtration slits

36
Q

what are the requirements for adequate filtration?

A

Adequate blood flow
Adequate hydrostatic pressure
Adequate vascular resistance

37
Q

what are the three parameters that give rise to glom filtration pressure?

A

i) Glomerular capillary blood pressure (GCP)
ii) Bowman’s capsule hydrostatic pressure (CP)
iii) Plasma colloid osmotic pressure (COP)

38
Q

what does GCP depend on?

A

afferent arteriole pressure; Also depends on the resistance to blood flow offered by the afferent and efferent arterioles

39
Q

where does the resistance contributing to GFR come from?

A

the fact that the afferent arteriole is larger in diameter than compared to eff art

40
Q

what is CHP/CP?

A

a opposing filtration to GCP; pushes fluid out of capsule into PCT

41
Q

what is BCOP/COP?

A

opposing pressure to filtration; created due to unequal protein distribution

42
Q

what are the net filtration pressure “eq’ns”?

A

GCP – CP – COP or GBHP – CHP – BCOP

43
Q

what areas need to be considered for GFR?

A

i) Glomerular capillary blood pressure

ii) Capillary surface area iii) Membrane permeability

44
Q

what is Kf?

A

the filtration coefficient; a function of glomerular surface area and membrane permeability

45
Q

how is GCP controlled primarily?

A

through the aff and eff arterioles; e.g. aff constricts under symp stimulation–>GCP decreases–> GFR decreases

46
Q

efferent arteriole does not have smooth muscle–>no constriction or dilation possible

A

ya

47
Q

what mechanisms regulate GCP?

A

i) Autoregulation
ii) Sympathetic control
iii) Hormonal regulation

48
Q

how is the GFR autoregulated and what is the purpose?

A

to maintain a constant glom cap pressure in spite of changes in systemic arteriole pressure; the aff arteriole is the major site of autoreg bc it is surrounded with symp sm muscle–> the diameter can be changed via myogenic or tubuloglomerular feedback
myogenic–>art sm muscle can contract when stretched (^ GCP)–>reduces amount of blood flowing through art; muscles relax and let art widen when blood flow is less
Tubuloglomerular feedback: control vascular tone of the aff and eff arterioles–involves chem released from macula densa cells of the tubular component within the juxtaglomerular apparatus (JA)

49
Q

what paracrine molecules do the MD cells release, and how do they affect the GFR?

A

ATP and adenosine; Causes vasoconstriction of the afferent arteriole Reduces the GFR
Stimulates calcium release in afferent arteriole smooth muscle cells, leading to contraction
Part of the tubuloglomerular feedback mechanism

50
Q

how does sympathetic control regulate GCP?

A

Sympathetic tone may increase in response to stress, trauma, exercise, decrease in effective circulating volume, etc.
Mediated by sympathetic nervous system input to kidneys
More for controlling systemic arterial pressure;
has 3 major
effects
1) It causes vasoconstriction
2) It enhances Na+ reabsorption by proximal tubular cells (Na+ moves back to the blood)
3) It stimulates renin secretion by the juxtaglomerular apparatus
All of these effects will give rise to an increase in arterial blood pressure
Afferent are innervated with sympathetic vasoconstrictor fibers far more than the efferent arterioles
GFR will be affected only when sympathetic stimulation is very intense

51
Q

how is GCP hormonally regulated?

A

via the RAAS–> involves homeostasis of Na conc, blood vol, and blood pressure

52
Q

which cells release renin?

A

granular cells next to the JA

53
Q

what primarily regulates Na conc and ECF volume?

A

aldosterone

54
Q

how does ANP regular GCP?

A

causes relaxation of glom mesangial cells (contractile cells)–>increases SA of glom–>enhances GFR

PHSI 208 (32 decks)

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