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Anatomy & Physiology II > Urinary System & Fluid Balance - Exam 3 > Flashcards

Urinary System & Fluid Balance - Exam 3 Flashcards

1
Q

What are the basic parts of a nephron?

A
  • Renal Corpuscle- contains the glomerular capsule and glomerulus
  • Proximal Convoluted Tubule- S-shaped tube located closest to the glomerulus
  • Nephron Loop / Loop of Henle - includes the ascending and descending limbs
  • Distal Convoluted Tubule - S-shaped tube located furthest from the glomerulus
  • Collecting Duct- trunk-like tube
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2
Q

What are the two different classes of nephrons?

A

Cortical nephron

Juxtamedullary nephron

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3
Q

What are the characteristics of cortical nephrons?

A
  • account for 85% of nephrons in the kidney
  • located entirely in the cortex
  • short nephron loop
  • glomerulus further from cortex-medulla junction
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4
Q

What are the characteristics of juxtamedullary nephrons?

A
  • originate close to the cortex-medulla junction
  • important in kidney’s ability to produce concentrated urine
  • long nephron loops
  • glomerulus closer to cortex-medulla junction
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5
Q

What components make up the filtration membrane?

A

fenestrated capillaries
basement membrane
podocytes

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6
Q

What is glomerular filtration rate (GFR)?

A

volume of filtrate formed each minute

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7
Q

What factors influence GFR?

A
  • hydrostatic pressure in glomerulus
  • hydrostatic pressure in capsule
  • colloid osmotic pressure
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8
Q

If there is a fall in blood pressure, what can be done to increase GFR?

A
  1. Myogenic Mech. - smooth muscle dilates to increase blood flow, increases GFR
  2. Tubuglomerular Mech. - macula densa cells detect low levels of NaCl due to longer filtration time, which causes vasodilation to allow for more blood flow and increased GFR
  3. Neural Controls - norepinephrine is released which causes vasoconstriction, which increases peripheral resistance and brings BP back up
  4. RAAS - granular cells release renin and catalyzes the formation of angiotensin II. This increases aldosterone secretion which increases blood volume, and causes vasoconstriction
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9
Q

Where does most reabsorption occur in the nephron?

A

proximal convoluted tubule

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10
Q

What provides the energy and means for reabsorbing almost every other substance, including water?

A

reabsorption of sodium by primary active transport

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11
Q

How does the initial active transport of sodium influence the reabsorption of other substances (water, glucose, amino acids etc.)

A
  • via secondary active transport

- apical carrier moves sodium down it’s concentration gradient as it cotransports another solute

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12
Q

What is tubular secretion?

A

excretion of unwanted substances that were reabsorbed

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13
Q

Why is tubular secretion important?

A
  • disposes of substances that are tightly bound to plasma proteins (drugs, metabolites)
  • eliminate undesirable substances or end products (urea, uric acid)
  • ridding body of excess potassium
  • controls blood pH
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14
Q

What are the renal functions?

A
  • excretion of wastes, H2O, drugs, excess electrolytes/macros
  • endocrine function - hormone release
  • regulation- solute, water, blood pH
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15
Q

What are the three major renal processes?

A
  • glomerular filtration
  • tubular reabsorption
  • tubular secretion
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16
Q

Glomerular filtration is a passive process driven primarily by what?

A

gradients

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17
Q

Glomerular capillaries are subject to high what?

A

blood pressure

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18
Q

How is net filtration pressure (NFP) measured?

A

outward pressures - inward pressures

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19
Q

What are the factors that maintain blood pressure?

A

cardiac output
peripheral resistance
blood volume

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20
Q

GFR must be relatively constant to do what?

A

maintain kidney function

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21
Q

What is the consequence of having a GFR that is too high or too low?

A

too high = lose too much

too low = too much absorption time

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22
Q

What triggers renin release?

A
  1. reduced stretch of granular cells AKA low BP

2. direct and indirect stimulation of granular cells

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23
Q

What are the direct and indirect stimulators of granular cells?

A

Direct - SNS triggers renal sympathetic nerves to active Beta-adrenergic receptors that cause granular cells to release renin
Indirect - low blood pressure causes vasoconstriction and slow filtrate movement, decreasing sodium concentration. Macula densa cells sense low sodium concentration and signal release of renin by releasing less ATP and/or prostoglandin PGE2

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24
Q

What are the effects of angiotensin II (Ang II) on systemic blood pressure?

A
  1. increasing peripheral resistance

2. increasing blood volume

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25
Q

Ang II increases peripheral resistance by doing what?

A

vasoconstriction

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26
Q

Ang II causes an increase in blood volume, which results in what?

A

-release of aldosterone, which increases sodium retention

release of ADH from posterior pituitary, which increases water retention

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27
Q

What is blood volume?

A

determined by the amount of water and sodium digested, excreted by kidneys in urine, and lost through GI tract, lungs and skin

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28
Q

Ang II can affect GFR by doing what?

A

constriction of efferent arterioles, which increases glomerular hydrostatic pressure, which increases GFR

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29
Q

When does tubular reabsorption occur?

A

as soon as filtrate enters the proximal convoluted tubule

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30
Q

What are the two routes of tubular reabsorption?

A

transcellular

paracellular

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31
Q

What is transcellular reabsorption?

A

across/through the cell

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32
Q

What is paracellular reabsorption?

A

alongside the cell

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33
Q

What transport types does tubular reabsorption utilize?

A

active and passive transport

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34
Q

What are the two phases of sodium reabsorption?

A
  1. primary active transport

2. secondary active transport

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35
Q

The secondary active transport of sodium aids in what?

A

reabsorption of nutrients, water, and ions

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36
Q

How does the movement of sodium aid in moving water and negatively charged ions?

A

movement of sodium establishes a strong osmotic gradient, and water moves via osmosis into peritubular capillaries. Aquaporins aid this process, and aid in obligatory water reabsorption

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37
Q

How does the movement of water help drive the reabsorption of solutes from the filtrate?

A

as water leaves the tubules, concentration of solutes increases and if able to, they follow their concentration gradients as well

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38
Q

How do the kidneys influence osmolality?

A

kidney functions to keep osmolality constant by regulating urine concentration

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39
Q

Why is regulating osmolality important?

A

prevents cells (especially in brain) from shrinking or swelling from osmotic movement of water

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40
Q

What are the three key players of osmolality?

A

long nephron loops
vasa recta
collecting ducts

41
Q

What is the long nephron loops orientation in the osmotic gradient?

A

create the gradient

countercurrent multipliers

42
Q

What is the vasa recta’s orientation in the osmotic gradient?

A

preserve the gradient

countercurrent exchangers

43
Q

What is the collecting duct’s orientation in the osmotic gradient?

A

use gradient to adjust osmolality

44
Q

What are the mechanisms that cause an increase in osmolality (and gradient) in the medulla?

A
  • dehydration
  • increase in osmolality
  • causes ADH release from posterior pituitary
  • increases number of aquaporins in collecting duct
  • causes increase in water absorption
  • creates small volume of concentrated urine
45
Q

What influence does ADH have on the kidney and urine concentration?

A
  1. Overhydration
    - ADH production decreases and osmolality falls
  2. Dehydration
    - ADH production increases and osmolality increases
46
Q

What influence does aldosterone have on the kidney and urine concentration?

A

If aldosterone is present during overhydration, it can further dilute the urine

47
Q

The three key players and how they affect the gradients of the kidney team together to form what?

A

medullary osmotic gradient

48
Q

What structure does the urine travel through after expulsion from the kidney?

A

ureters — bladder — urethra

49
Q

What is the chemical composition of urine?

A

95% water, 5% solutes

50
Q

What are the normal solutes present in urine in decreasing concentration?

A 
Urea
Sodium
Potassium 
PO4(3-)
SO4(2-)
creatinine
uric acid
calcium
magnesium
HCO3(-)
51
Q

What is urine used for?

A

to test for pathologies

52
Q

What does the process of micturition (urination) involve?

A
  1. contraction of detrusor muscle (smooth muscle)
  2. opening of internal urethral sphincter (smooth muscle)
  3. opening of external urethral sphincter (skeletal muscle)
53
Q

How does the brain receive urination signals?

A

signals of fullness from bladder are sent to pons and higher brain centers

54
Q

What happens to cells if they are surrounded by a hypertonic solution?

A

cells shrink as water moves to area of lower concentration

55
Q

What happens to cells if they are surrounded by a hypotonic solution?

A

cells swell as water moves to area of lower concentration (the cell)

56
Q

What are the major locations of sodium?

A

blood plasma

interstitial fluid

57
Q

What are the major locations of potassium?

A

intracellular fluid

58
Q

What are the major locations of calcium?

A

blood plasma

interstitial fluid

59
Q

What are the major locations of chloride?

A

blood plasma

interstitial fluid

60
Q

What are the major locations of bicarbonate ions?

A

blood plasma

interstitial fluid

61
Q

What are the major locations of proteins?

A

blood plasma

intracellular fluid

62
Q

How is metabolism a source of water?

A

water is a by-product of oxidation of carbs and fatty acids

water released from break down of glycogen

63
Q

What is the hormonal response to a rise in osmolality?

A

stimulate secretion of ADH

increases water absorption and concentrated urine

64
Q

What is the hormonal response to a decrease in osmolality?

A

suppresses ADH release

decreases water absorption and produces less concentrated urine

65
Q

What are the resulting effects of hypotonic hydration on osmolality and cells?

A

hyponatremia (low ECF sodium concentration)

  • promotes net osmosis into cells
  • causes cells to swell and decreases osmolality
66
Q

What are the general causes of edema?

A

increased fluid out
decreased fluid returning to blood
blocked removal of excess interstitial fluid

67
Q

How is estrogen linked to fluid retention during a female’s menstrual cycle?

A

estrogen is like aldosterone, increasing the amount of NaCl reabsorbed. Water follows NaCl, causing increased fluid retention

68
Q

How can hyperkalemia lead to sudden cardiac death ? (think action potentials)

A

increased extracellular potassium reduces myocardial excitability
suppressed impulse generation by SA node, resulting in eventual cardiac death

69
Q

What gland and hormone regulates calcium levels in the blood?

A

parathyroid hormone released by parathyroid glands

70
Q

How much of your body weight is composed of intracellular fluid?

A

40% of body weight

71
Q

How much of your body weight is composed of interstitial fluid?

A

80% of ECF

ECF makes up 20% of body weight

72
Q

How much of your body weight is composed of plasma?

A

20% of ECF

73
Q

Water is the universal what?

A

solvent

74
Q

Solutes are classified as what?

A

nonelectrolytes and electrolytes

75
Q

Electrolytes dissociate into what?

A

ions

76
Q

Nonelectrolytes are what kind of chemical compound?

A

mostly organic

no charged particle created

77
Q

Osmotic and hydrostatic pressure regulates what?

A

continuous exchange and mixing of fluids

78
Q

Change in solute concentration = change in what?

A

water flow

79
Q

Osmolality is maintained at what level?

A

280-300 mOsm

80
Q

What is obligatory water losses?

A

insensible water loss from lungs, skin, feces, urine

81
Q

What is dehyration?

A 
ECF water loss due to 
hemorrhaging
severe burns
prolonged vomiting
diarrhea
profuse sweating
water deprivation
82
Q

What can dehydration lead to?

A 
weight loss
fever
mental confusion
hypovolemic shock
loss of electrolytes
83
Q

Why can dehydration lead to a dry/”cotton” mouth?

A

loss of water in saliva and mucosa

decreased saliva production

84
Q

Can water kill you?

A

Yes, drinking too much water can cause cells to swell, and could later cause cerebral edema

85
Q

What is the treatment option for hypotonic hydration?

A

administration of IV hypertonic saline to reverse osmotic gradient

86
Q

What are electrolytes?

A

salts
acids
bases
some proteins

87
Q

Salts are involved in what?

A

fluid movement
provide minerals for excitability
secretory activity

88
Q

How do salts enter and leave the body?

A

enter - foods, fluids, small amounts during metabolic activities
loss- perspiration, feces, urine, vomit

89
Q

99% of the body’s calcium is found where?

A

bone

90
Q

The calcium in ECF is important for what?

A

blood clotting
cell membrane permeability
secretory activities
neuromuscular excitability

91
Q

How does PTH promote an increase in calcium?

A
  1. Bone - PTH activates osteoclasts which causes release of calcium into blood
  2. Kidneys - PTH increases calcium reabsorption and decreases phosphate reabsorpion
  3. Small Intestine - PTH enhances intestinal absorption of calcium
92
Q

How does progesterone alter sodium?

A

decreases sodium reabsorption (blocks aldosterone)

93
Q

What is the normal pH values for arterial blood, venous blood and interstitial fluid, and ICF?

A

arterial blood - 7.4
venous blood and IF- 7.35
ICF - 7.0

94
Q

What is alkalosis/alkalemia?

A

arterial pH greater than 7.45

95
Q

What is acidosis/acidemia?

A

arterial pH less than 7.35

96
Q

Most hydrogen is produced by metabolism via what?

A
  • lactic acid from anaerobic respiration of glucose
  • fatty acids and ketone bodies
  • conversion of CO2 to HCO3
97
Q

What is a system of one or more compounds that act to resist pH changes when strong acid or base is added?

A

chemical buffer systems

98
Q

What are the types of chemical buffer systems and which one is the most important?

A

bicarbonate, phosphate, and protein buffer systems

Bicarbonate buffer system is most important

Anatomy & Physiology II (15 decks)

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