renal Flashcards

1
Q

What four systems are involved in excretion?

A

urinary, respiratory, digestive and integumentary

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2
Q

microscopic filtering units of the kidneys composed of renal corpuscle, renal tubules and a rich blood supply?

A

The nephron

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3
Q

What is the functional unit of the kidney?

A

The nephron

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4
Q

Where are the nephrons located?

A

mostly in the renal cortex with some tubules extending into renal pyramids of the medulla

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5
Q

What four processes are required for urine formation?

A

glomerular filtration
tubular reabsorption
tubular secretion
excretion

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6
Q

Define glomerular filtration.

A

glomerular filtration of water and solutes from the glomerular capillaries blood into Bowman’s capsular space
non-selective filter

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7
Q

Define tubular reabsorption.

A

tubular reabsorption of useful substances from renal tubules filtrate into the peritubular capillaries blood

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8
Q

Define tubular secretion and then excretion.

A

tubular secretion of waste products from the peritubular capillaries blood into the renal tubules filterate. Excretion then occurs as urine.

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9
Q

What is the ‘filtration membrane’ fromed from? What is the glomerular capillary hydrostatic pressure?

A

formed by the glomerular capillary wall and the visceral layer of Bowman capsule
60 mmHg

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10
Q

What does GFR stand for and what is the average L/day?

A

glomerular filtration rate

180 L/day

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11
Q

What is the equation for filtration fraction?

A

GFR/Renal Plasma Flow

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12
Q

In comparison to the glomerular capillary pressure; what is the blood capillary pressure in other parts of the body?

A

Ranges form 7-17 mmHg; opposed to the 60 mmHg in the glomerular capillary

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13
Q

What is used to calculate the net filtration pressure (NFP)?

A
Blood hydrostatic pressure (BHP), Colloid osmotic pressure (COP), and the capsular pressure (CP)
BHP 60 mmHg OUT
COP -32 mmHg IN
CP -18 mmHg IN
= 10 mm Hg OUT
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14
Q

What is fluid in the capsular space called and what does it NOT consist of?

A

glomerular filtrate- no blood cells, plasma proteins or fatty acids

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15
Q

What does glomerular filtrate contain?

A

metabolic wastes such as urea & uric acid

useful substances such as water, organic nutrients & electrolytes

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16
Q

Regulation is done by controlling the amount of glomerular blood flow. what effect does dilation of the afferent arteriole and constriction of efferent arteriole have on the GFR?

A

increase in GFR

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17
Q

Regulation is done by controlling the amount of glomerular blood flow. what effect does constriction of the afferent arteriole and dilation of efferent arteriole have on the GFR?

A

decrease in GFR

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18
Q

What 3 hormones DECREASE GFR?

A

NE, Epi, and endothelin

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19
Q

What 3 hormones INCREASE GFR?

A

PG, bradykinin, and enothelial-derived NO

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20
Q

What is autoregulation of GFR?

A

regulation of GFR by the juxtaglomerular/ macula densa apparatus that is found in every nephron

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21
Q

What is neural regulation of GFR?

A

sympathetic nervous system stimulation during exercise or in circulatory shock that DECREASES GFR

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22
Q

In tubular reabsorption, what is ultrafiltration?

A

Bulk flow- from the interstitial fluid through the peritubular capillary wall into the blood

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23
Q

In tubular reabsorption, what is transport maximum?

A

the amount of substance that can be transported before the transport proteins for that substance becomes fully saturated

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24
Q

How many liters of urine are excreted a day? How manyliters of water are reabsorbed per day?

A

1-2 liters of urine excreted/ day

148-178 liters of water are reabsorbed /day

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25
Q

Where does most of the water reabsorption take place?

A
  • 65% in the proximal convoluted tubules (PCT)
  • 15% in descending limb of loop of Henle (LOH)
  • 10% in distal convoluted tubules (DCT)
  • 10% in collecting ducts (CD)
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26
Q

How much water is reabsorped in the ascending loop of Henle?

A

NONE

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27
Q

What is passive water reabsorption coupled to?

A

passive water reabsorption by osmosis is coupled to sodium reabsorption

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28
Q

What is considered the ‘obligatory’ water reabsorption?

A

80%- in PCT and descending LOH

29
Q

What water channel aids ‘obligatory’ water reabsorption? is it always open?

A

Aquaporin I

yes, it is always open

30
Q

What is the ‘facultative’ water reabsorption?

A

20%- in DCT and CD

-this is variable depending on degree of body hydration

31
Q

Facultative water reabsorption is controlled by what?

A

ADH activation of Aquaporin 2

32
Q

What is the renal clearance of creatinine?

A

filtration only

33
Q

What effect does ADH have on the cells of the DCT and CD?

A

makes their cells more permeable to water by activation of aquaporin 2

34
Q

In regards to urine concentration; when is the secretion of ADH stimulated and where?

A

when the body water content decreases, the hypothalamic osmoreceptors are activated and secretion of ADH from the posterior pituitary is stimulated

35
Q

How does urine dilution occur?

A

when body water content increases, the hypothalamus stops secreting ADH causing the DCT and CD to become less permeable to water reabsorption. Aldosterone secretion is also decreased and less salt and water is reaborbed this leads ton large volume of light colored urine

36
Q

What is the minimum urine volume that must be excreted by the kidneys to get rid of metabolic waste and excess ions per day? Why is there a need for a minimum?

A

0.5 liters/ day
kidneys cannot get rid of excess metbolites and ions without water
‘we would be like a salt shaker’

37
Q

Why can we control (to some extent) when we pee?

A

The external urethral sphincter is made of skeletal muscle and is controlled by the punendal nerve

38
Q

what is the process for the micturition reflex?

A

singlas from sensory stretch receptors in bladder–> pelvic nerve afferent fibers–>n sacral spinal cord–> pelvic nerve motor fibers–> detrusor mucles contraction and internal urethral sphincter relaxtion–>’feeling you need to pee’

39
Q

What is atonic bladder?

A

also called overflow incontinence, destruction of sensory nerve fibers abolish the micturition reflex contractions, this causes the bladder to fill and start dripping
usually caused by syphilis and sacral nerve injury

40
Q

What is automatic bladder?

A

loss of conscious control of urination due to spinal cord injury above the sacral region

41
Q

What is uninhibited neurogenic bladder?

A

The loss of inhibitory signals to the bladder promote frequent urination can be due to nerve damage, UTIs, pregnancy
urge to go never goes away

42
Q

Potassium secretion is increased by what 4 factors?

A

increased extracellular potassium, increased tubular flow rate, aldosterone, alkalosis

43
Q

How much filtered calcium is reabsorbed? where does most of the reabsorption occur?

A

99%
65% proximal convoluted tubule
30% LOH

44
Q

How is phosphate reulated in the renal system?

A

by an overflow mechanism

80% is reabsorbed in the proximal convoluted tubules

45
Q

How is magnesium excretion increased and how is it regulated?

A

inc Mg+ conc, inc Ca2+ conc, inc extracellular fluid
regulated by changing tubular reabsorption: 65% reabsorption in LOH
25% in PCT

46
Q

In what sceraios might blood AND ECF volumes be increased?

A

CHF and increased vascular capacity

47
Q

In what scenarios would ECF be increased but not blood volume?

A

liver cirrhosis (decreased plasma proteins synthesis), nephrotic syndrome (loss of plasma proteins in the urine)

48
Q

What three systems regulate acid-base balance in the body fluids?

A

the buffer system
the respiratory system
the kidneys

49
Q

What is the bicarbonate buffer system equation?

A

CO2+ H2O H2CO3 H+ + HCO3

NaHCO3 Na+ HCO3

50
Q

What is the phosphate buffer system?

A

NaH2PO4 NaHPO4 + H+

51
Q

What is the protein buffer system?

A

Hb+ H+ HHb

52
Q

What is the cause of respiratory acidosis?

A

respiratory center damage, respiratory obstruction, lung tissue destruction, gas exchange impairment

53
Q

What is the cause of respiratory alkalosis?

A

hyperventilation, high altitude

54
Q

What is metabolic acidosis and what are the causes of it?

A

decreased ECF bicarb concentration

can be caused by kidney failure, diarrhea, diabetes mellitus, ingestion of acids

55
Q

What is metabolic alkalosis? What can the causes be?

A

Increased ECF bicarb conc
can be caused by diuretics treament, alkaline, drugs ingetion, excess aldosterone secretion, gastric acid loss with vomiting

56
Q

How is acidosis corrected?

A

Renal commpensation– excrete acidic urine, reabsorb and make new bicarb
respiratory- inc rate of breathing

57
Q

How is alkalosis corrected?

A

renal- decreased H+ excretion, increased bicarb excretion

respiratory- decreased rate of breathing

58
Q

treatment for acidosis?

A

sodium bicarb, sodium lactate, or sodium gluconate

59
Q

treatment for alkalosis?

A

ammonium chloride

60
Q

when are diuretics used?

A

alleviate vascualr hypervolemia, edema, CHF, hypertension

61
Q

What is the mechanism of action for diuretics?

A

osmotic effects, interference with membrane protein transporters, enzyme inhibition or hormone receptor blockage

62
Q

Central diabetes insipidus is a kidney disease where what occurs?

A

failure of hypothalamus to priduce ADH or posterior pituitary to release ADH

63
Q

What is nephronic diabetes insipidus?

A

inability of kidney tubules to respond to ADH stimulation

64
Q

Azotemia/ Uremia definition?

A

retention of water, eletrolytes and waste products into the blood

65
Q

What is nephrotic syndrome?

A

protein excretion in the urine

66
Q

In regards to acute kidney injury; what is the difference between prerenal, intrarenal and postrenal?

A

prerenal- caused by decreased blood supply
intrarenal- caused by kidney diseases and tissue abnormalities
postrenal- caused by any urine outflow obstruction

67
Q

What is chronic kidney disease?

A

irreversible loos of functional nephrons to less than 25% of normal due to blood, kidneys or urinary tract disorders

68
Q

What is end-stage renal failure?

A

kidney transplant or dialysis is required for life