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Flashcards in Urinary System Deck (40):
1

Kidney main functions

1. maintain blood vol
2. balance pH
3. manage H2O and Ions
4. get rid of wastes, drugs, hormones
5. endocrine
--> erthropoietin
--> renin

2

nephron

functional unit (renal corpuscle and tubes)

3

3 steps of urine formation

glomerular filtration
tubular absorption
tubular secretion

4

glomerular filtration

20% of plasma is filtered into the bowmans capsule via bulk flow.

filtration membrane: fenestrations (glom), basement membrane (velcro), podocytes (capsule wall)

5

filtrate

vitamins, H2O, aa, glucose, fa, ions, small proteins, urea. NOT LARGE PROTEINS
PH 7.45 from arterial blood

6

net filtration pressure

GHP favours filtration 55 mmhg
BOP oppose 30
CHP oppose 15
COP favours 0

7

glomerular filtration rate

180 L/day filtered
entire plasma filtered 65x/day
<1% of filtrate is left when reaching the collecting duct

8

regulation of GFR

intrinsic (resting to moderate exercise)
myogenic and juxtamedullary apparatus (macula densa cells in the afferent art.

extrinsic regulation
mostly SNS no PSNS. constriction of both arterioles

9

myogenic

increase bp --> stretch receptors --> aff art smooth muscle constricts --> less blood into glomerulus --> GFR decreases

10

juxtamedullary apparatus

increase in bp --> increase in GFR --> greater [NaCl] in filtrate --> macula densa sense it --> make smooth m. in aff art constrict. --> GFR decreases.

11

extrinsic reg

increase in bp --> increase in GFR --> increase SNS --> aff art constricts --> less blood in GFR goes down.

resistance increases, blood flow decreases, GFR decreases

BACK FLOW decrease in bp --> decrease GFR --> increases SNS --> eff art constricts --> less blood out GFR increases.

resistance increases, blood flow decreases, GFR goes up.

12

extrinsic regulation extreme exercise

decrease in GFR to conserve water.

13

NFP can change...

BOP AND CHP

BOP
- BOP increases when dehydrated DECREASE GFR
- BOP decreases when there is leakage of proteins, burns and nephrotic syndrome INCREASE GFR

CHP
- urinary tract obstruction when inflammed, prostate enlargement, kidneystones) urine gets backed up, increase CHP GFR DECREASES.

14

Tubular reabsorption

reabsorb 99% of filtrate from tubules to the peritubular cap. and vasa recta capillaries

can be active (glucose, ca, aa, na) or passive (h20, urea, cl)

15

absorption in the PCT

unregulated
100% glucose and AA
66% na
small proteins (endocytosis --> aa --> blood)
vitamins
obligatory (unregulated) reabs of h20

causes filtrate volume to go down to 300 mOsm/L = plasma as well

16

abs at Loop of henle

DL: perm to water
AS: perm to salt (200 mOsmol/ L gradient between ISF and filtrate)

17

DCT initial

reabs NaCl, Ca, Cl
imperm to water

18

DCT late

reabs NaCl using aldosterone and angiotensin 2
reabs water using ADH

19

nephrons absorb

99% of water
99.5% salt
50 % urea
100% gluc

20

Tubular secretion

peritubular blood into filtrate
a) wastes (urea, uric acid, some hormones)
b) K via aldosterone
c) h or NH4 (pH regulation)

21

Counter current multiplier mechanism

make urine concentration range from 100 to 1200 mOsmol/L
made by the juxtamedullary nephron
vertical osmotic gradient

1) in loop of henle
DL: water leaves the filtrate and into the ISF to match osmotic pressure. (osmosis)
AL: Na leaves by AT 200 mOsm/L gradient between the filtrate and the ISF. leaves the AL at 150 mOsm/L.
this is less than the plasma because AL is imperm to water and Na is transported out against its concentration gradient.

2) initial DCT
- more na is reabs via active transport, becomes 100 mOsm/L

3 late DCT and CD
- na is absorbed when angiotensin is present to release aldosterone and ADH.
--> urine becomes more concentrated, this happens when bp is low, so that our bp doesnt get any lower

OR not absorbed if ANP is released.
--> inhibits the rel of aldo and ADH.
--> happens when BP is high so that we can release pressure. urine is dilute, no H2O or salt enters or leaves and the urine is secreted at the same 100 mOsm/L

22

regulation of [Urine]

hormonal
1) renin
2) aldosterone
3) ADH
4) ANP

SNS no PSNS

23

regulation of [Urine] RENIN-ANGIOTENSIN SYSTEM

renin secreted from the aff and eff of juxtaglomerular cells

increased renin when... BP is LOW
1. SNS is increasing
2. decrease stretch of juxtaglomerular cells
3. decrease in NaCl filtrate

decreased renin when... BP is HIGH
1. SNS decreasing
2. ADH and aldosterone
3. increase stretch of juxtaglomerular cells
4. increase in NaCl in filtrate.

24

aldosterone is secreted from the ....

adrenal cortex

25

ADH is secreted from the...

brain

26

regulation of [Urine] ADH

anti diuretic hormone
increase the reabs of water into the blood

increase in ADH when...
1. low bp
2. increase in angiotensin
3. increase in plasma osmolarity
4. nicotine and nausea

decrease in ADH when...
1. high bp
2. decrease in angiotensin
3. increase in ANP
4. alcohol

27

diabetes insipidus

no ADH or receptors
can not conserve water.
pee will have normal amounts of glucose and we will have normal blood. Increase in thirst.

28

regulation of [Urine] ALDOSTERONE

increase when there is more angio 2, and high plasma K

turns on genes that increase the number of Na/KATPase in late DCT, CD

increase na reabs (cl and water follow) and gets rid of K.

29

regulation of [Urine] ANP

increase of this when bp increases.
decreased renin therefore decrease in bp, increase in urine vol.

30

regulation of [Urine] SNS

increase causes constriction of aff and eff.

myogenic response is stronger in the kidney, so the increase in MAP causes the aff vasocon. to reduce BP
instead of the SNS decreasing its activity by reducing renin and increasing ANP to reduce BP. SO GFR REMAINS CONSTANT

As FOR MAP... the lack of ADH and aldosterone means that no water and salt is being reabs, therefore urine vol increases and blood vol decreases. MAP DECReASES.

OVERALL THE INTRINSIC MECHS REGULATE GFR AND EXTRINSIC REGULATES MAP.

31

IF A LARGE decrease in BP and blood Vol

EXTRINSIC MECHS are STROnger DECREASE IN GFR.

32

Urine is made of...

water
1. urea: from aa met 50%

2. uric acid (highly unsoluble) from nucleic acid breakdown 10% reabs

3. creatinine: production and excretion is constant (used to measure GFR)

4. regulated substances such as ions

ph is 4.5-8

33

Abnormal urine

1. protein = proteinuria (albuminuria) due to increase permeability of glom.
- nephoritic syndrome (multiple causes such as diabetes millitus, heavy metals, infections)
- glomerulonephritis (inflammation due to infection elsewhere.

2. glucose = glycosuria
- temporary - glucose IV
-pathological
diabete milletus: high blood glucose absorbed in PCT normally but overwhelmes the PCT --> glucose in urine and increase in urine osmotic pressure --> high urine volume
AKA U PEE ALOT
Congenital - no glucose transporters, cant reabs water.
high urine vol. increase thirst. blood gluc normal or low.

34

Micturition relfex

urinary bladder and urethra. contraction of the detrusor muscle and relaxation of the internal sphincter.

35

renal plasma clearance

volume of plasma cleared of a substance in 1 min. rate a substance is removed from blood.

PC of A = vol of urine x [A] in urine / [A] in arterial plasma

inulin is a carb that is not metabolized, reabs, or secreted. JUST FILTERED. Used to measure GFR

36

PC < GFR

reabs

37

PC > GFR

filtered (penicilin and H)

38

Acid Base Balance

regulation of gree H in ECF ECF ECF ECF!!!
H comes from metabolism (ENERGY USE)!

acidosis 6.8-7.35
alkalosis 7.45-8.0

2 systems
respiratory system
renal system

39

Acid Base Balance ACIDOSIS

acidosis
Increase of H in the ECF
depressed, coma, irregular heart beat
urine contains H, HPi, NH4 little HCO3

RESP ACIDOSIS
his means that ph is low and the CO2 is high. this
occurs due to hypoventilation.
--> when the lungs are damaged or the resp centeres are damaged.
resp sys. cant do anything
renal system
- kidneys increase secretion of H and HCO3 abs in blood

METABOLIC ACIDOSIS
- increase in H other than b/c of CO2
- diarrhea, loss of HCO3
- diabetes mellitus : increase fat metabolism, no glucose therefore ketones
- strenous exercise: lactic acid
- renal failure

so the resp sys. peripheral chemoreceptors increases ventilation to decrease CO2, then when CO2 gets too low the central chemoreceptors decrease ventilation to increase is again.

if kidneys not damaged this increase secretion of H and HCO3 in blood

40

Acid Base Balance ALKALOSIS

overexcitation of the CNS, spasms in skel m.
urine contains: HCO3, little H, NH4, no HPi

RESP ALKALOSIS
decrease in CO2. ph goes up H too little.
hyperventilation

Solutions
Resp, not unless hyperventialation was voluntary
Renal: decrease H secretion, and Less HCo3 to blood (lost in urine)

METABLOIC ALKALOSIS
increase in pH, decrease in H other than CO2 change

solution
RESP: decrease ventilation (peripheral) --> central then balances it
RENAL: decrease H secretion and less HCO3 to blood.