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Biology - Chapter 19-29 > Chapter 27 - Fluid, Electrolyte, and Acid-Base Homeostasis > Flashcards

Chapter 27 - Fluid, Electrolyte, and Acid-Base Homeostasis Flashcards

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1
Q

What is intracellular fluid?

A

Fluid within body cells (cytosol)

- 66% of body fluid is intracellular

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2
Q

What is extracellular fluid?

A

Fluid outside of body cells
- 33% of ALL body fluid is extracellular
(- 80% is interstitial fluid)
- 20% is plasma (in the blood)

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3
Q

What is interstitial fluid?

A

Extracellular fluid that occupies space between cells
- includes lymph, cerbrospinal fluid, synovial fluid, aqueous humor, vitreous body, endolymph, perilymph, pleural, pericardial and peritoneal fluids

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4
Q

What percentage of lean adults is composed of fluids? Males? Females?

A

Males are 60% fluid

Females are 55% fluid

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5
Q

What are two barriers that separate intracellular fluid, interstitial fluid and blood plasma?

A
  1. Plasma membrane of individual cells

2. Blood vessel walls

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6
Q

What is fluid balance?

A

When the required amounts of water and solutes are present

- correctly proportioned

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7
Q

What is the primary means of water movement between intracellular fluid and interstitial fluid?

A

Osmosis

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8
Q

What are electrolytes?

A

Inorganic compounds that dissociate into ions

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9
Q

What are the three sources of water for the body?

A
  1. Ingested liquids (1600 mL per day)
  2. Ingested solids (700 mL per day)
  3. Metabolic water (200mL per day)
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10
Q

What is metabolic water?

A

Water that is produced in the body

- mainly when electrons are accepted by oxygen during aerobic cellular respiration

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11
Q

What are the fours ways that the body is able to lose water?

A
  1. Excretion by kidneys (1500 mL per day)
  2. Skin evaporation (600 mL per day)
  3. Lung exhalation (300 mL per day)
  4. Feces (100 mL per day)
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12
Q

What is known as the thirst center and what does it do?

A

Hypothalamus

- governs the urge to drink

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13
Q

What is dehydration?

A

Water loss > water gain

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14
Q

How is excess body water or solutes mainly controlled?

A

In the urine

  • Na+ and Cl- are important ions
  • water follows solutes in osmosis
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15
Q

What are the three pathways in which dehydration stimulates thirst?

A
  1. Dry mouth, from decreased flow of saliva
  2. Increased blood osmolarity, stimulates osmoreceptors in hypothalamus
  3. Decreased blood volume, decreased blood pressure, kidneys release renin –> increased angiotensin II formation, stimulates hypothalamus
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16
Q

What regulates how much Na+ and Cl- is lost through urine?

A

Hormones!

- angiotensin II, aldosterone and atrial natriuretic peptide

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17
Q

What is the major hormone that regulates water loss?

A

Antidiuretic hormone (ADH) (vasopressin)

  • more water reabsorption in the kidneys
  • triggered by thirst, decrease in blood volume, hyperventilation, vomiting, diarrhea
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18
Q

What is the effect of angiotensin II on water levels in the body?

A

Stimulates secretion of aldosterone

- reduces loss of water in urine

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19
Q

What is the effect of aldosterone on water levels in the body?

A

Promotes urinary reabsorption of Na+ and Cl-, increases water reabsorption by osmosis
- reduces loss of water in urine

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20
Q

What is the effect of atrial natriuetic peptide (ANP)?

A

Promotes natriuresis, elevated urinary excretion of Na+ and Cl-, accompanied by water
- increases loss of water in urine

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21
Q

How does a change in osmolarity of INTERSTITIAL fluid change cell size?

A

Increase in osmolarity = draws water out of cells, they shrink
Decrease is osmolarity = draws water INTO cells, they swell

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22
Q

What is water intoxication?

How does it occur?

A

When someone drinks more water then the kidneys can process (15 mL per minute)
- state in which excessive body water causes cells to swell dangerously

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23
Q

What are the four functions of electrolytes?

A
  1. Control the osmosis of water between fluid compartments
  2. Help maintain the acid-base balance
  3. Carry electrical current
  4. Serve as co-factors for enzyme activity
24
Q

What is the main difference in composition between the extracellular fluids (blood plasma and interstitial fluid)?

A

Blood plasma contains many protein anions, interstitial fluid contains very few

25
Q

What is the most abundant cation and anion in extracellular fluid?

A

Na+ and Cl-

26
Q

What is the most abundant cation and anion in intracellular fluid?

A

K+ and HPO4-2

27
Q

What are the functions of sodium in the body?

A
  1. Generation and conduction of action potentials
  2. Maintains electrolyte balance
    - controlled by aldosterone (increases renal reabsorption of NA+), ADH (decrease Na+ but retaining more water) and ANP (increases Na+ excretion)
28
Q

What are the function of chloride in the body?

A
  1. Balance levels of anions
  2. Part of gastric juices
    - ADH regulates Cl- by controlling water retention/loss
29
Q

What are the functions of potassium in the body?

A
  1. Resting membrane potential
  2. Repolarization phase of action potentials
  3. Maintains normal intracellular volume
  4. Helps regulate pH of body fluids
    - controlled by aldosterone
30
Q

What is the function of bicarbonate in the body?

HCO3-

A
  1. Increases blood flows through capillaries
  2. Helps maintain correct balance of anions
    - kidneys regulate HCO3-
31
Q

What is the function of calcium in the body?

A
  1. Forms bones
  2. Role in blood clotting
  3. Neurotransmitter release
  4. Maintenance of muscle tone
  5. Excitability of nervous and muscle tissue
32
Q

What is the function of phosphate in the body?

A
  1. Important buffer of H+ in body fluids
33
Q

What are the three main systems that help balance H+ levels in the body?

A
  1. Buffer systems
  2. Exhalation of carbon oxide
  3. Kidney excretion of H+
34
Q

How do buffer systems act to balance out H+ levels?

A

Quickly bind temporarily to H+

- raise pH of body fluids without removing H+ from the body

35
Q

How does the exhalation of carbon dioxide affect H+ levels?

A

Increasing rate and depth of breathing = more CO2 is exhaled
- this reduces the level of carbonic acid in the blood, which raises blood pH
(reduces blood H+ level)

36
Q

How does kidney excretion of H+ affect the H+ levels in the body?

A

The slowest mechanism but only way to eliminate acids other than carbonic acid
- through their excretion in urine

37
Q

What does a buffer system consist of?

A

Weak acid and weak base (salt)

- converts strong acids and bases into WEAK ACIDS AND BASES

38
Q

What happens during the protein buffer system?

A

The free carboxyl group (-COOH) acts like an acid by releasing H+ when pH rises
- free H+ can then react with excess OH- to form water
The free amino group (NH2) can act as a base by combining with H+ when pH falls
- forms NH3

39
Q

What functions as an important buffer in red blood cells?

A

Hemoglobin

40
Q

What is the carbonic acid-bicarbonate buffer system based on?

A

Bicarbonate ion (HCO3-) = acts as a weak BASE
- picks up excess H+ to form carbonic acid
Carbonic Acid (H2CO3-) = acts as a weak ACID
- can lose an H+ to form the bicarbonate ion

41
Q

What is important to note about the carbonic acid-bicarbonate buffer system?

A

Cannot protect against pH changes due to respiratory problems in which there is an excess or shortage of CO2
- b/c CO2 and water combine to form H2CO3

42
Q

How does the phosphate buffer system function?

A

OH- + H2PO4- (weak acid) –> water + HPO4-2 (weak base)
OR
H+ + HPO4-2 (weak acid) –> H2PO4- (weak acid)

43
Q

Why is the phosphate buffer system important?

A

Important regulator of pH in the cytosol

44
Q

How does the exhalation of carbon dioxide affect pH?

A

An increase in CO2 concentration = lower pH, more acidic

A decrease in CO2 concentration = raises pH, more basic

45
Q

What acid combines with carbon dioxide during the exhalation of carbon dioxide to affect pH levels?

A

H2CO3 (carbonic acid)

46
Q

What happens to pH levels if you slow your breathing? Speed up your breathing?

A

Slow breathing = less CO2 exhaled, increase H+, more acidic, lower pH
Fast breathing = more CO2 exhaled, decrease H+, more basic, higher pH

47
Q

How do the kidneys function to excrete H+?

A

Renal tubules secrete H+ into urine and reabsorb HCO3- so it is not lost in urine

48
Q

What is acidosis?

A

When blood pH is BELOW 7.35

  • causes depression of CNS
  • disoriented, coma
49
Q

What is alkalosis?

A

When blood pH is ABOVE 7.45

  • over excitability of CNS
  • convulsions, muscle spasms
50
Q

What is compensation?

A

The physiological response to an acid-base imbalance

  • acts to normalize arterial blood pH
  • can be partial or complete
51
Q

What is respiratory compensation?

A

Hyperventilation or hypoventilation can help bring pH back toward the normal range
- occurs if imbalance due to metabolic causes

52
Q

What is renal compensation?

A

Changes in secretion of H+ and reabsorption of HCO3- can reverse changes
- due to RESPIRATORY causes

53
Q

What is respiratory acidosis?

A

Abnormally HIGH partial pressure of CO2

  • inadequate exhalation of CO2 causes the blood pH to drop (acidic)
  • causes include: emphysema, pulmonary edema, injury, airway obstruction
  • renal compensation: excrete H+ and reabsorp HCO3-
54
Q

What is respiratory alkalosis?

A

Abnormally LOW partial pressure of CO2

  • increase in pH (basic)
  • results in hyperventilation
  • causes: high altitude, pulmonary disease, stroke
  • renal compensation: decrease excretion of H+
  • breathe into a paper bag!
55
Q

What is metabolic acidosis?

A

LOW HCO3- level

  • causes blood pH to decrease
  • causes: diarrhea, renal dysfunction, accumulation of another acid, failure of kidneys to excrete H+
  • respiratory compensation may bring back to normal levels
56
Q

What is metabolic alkalosis?

A

HIGH HCO3- levels

  • from excessive intake of alkaline drugs or excessive vomiting (loss of HCl)
  • HYPOventilation may restore it

Biology - Chapter 19-29 (11 decks)

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