A&p Ii Lecture Exam 4 Ch 24

Front 1

How much of the total body composition is fluid?

Back 1

~50%-60%

Front 2

Define minerals

Back 2

- Inorganic substances
- dissolved within and form ions called electrolytes

Front 3

Two types of fluid compartments

Back 3

- Intracellular fluid (ICF)
- extracellular fluid (ECF)

Front 4

Which is usually more, intracellular fluid or extracellular fluid?

Back 4

Intracellular fluid

Front 5

Intracellular fluid characteristics

Back 5

- Water content varies most here due to variations in tissue type (fat vs. muscle)
- Distinct from ECF due to plasma membrane transport

Front 6

Examples of extracellular fluid

Back 6

- interstitial fluid
- plasma
- cerebral spinal fluid
- lymph

Front 7

Fluid loss occurs....

Back 7

- Urination
- Evaporation from skin
- Evaporation at lungs
- Loss in feces

Front 8

Fluid gain occurs....

Back 8

- water content in food
- water consumed as liquid
- metabolic water produces during catabolism

Front 9

Fluid Shift

Back 9

- Maintain balance of ICF and ECF compartments (osmotic equilibrium)
- Loss of water from ECF is replaced by water in ICF

Front 10

Dehydration

Back 10

- results in long term transfer that cannot replace ECF water loss
- Homeostatic mechanisms to increase ECF fluid volume will be employed

Front 11

Mineral Balance

Back 11

Equilibrium between ion absorption and secretion

Front 12

Where does major ion absorption occur?

Back 12

intestine and colon

Front 13

Where does major ion secretion occur?

Back 13

- kidneys
- sweat glands (variable)

Front 14

Where are ion reserves stored?

Back 14

Skeleton

Front 15

Sodium balance

Back 15

- when sodium gains = losses
- Relatively small changes in Na+ are accommodated by changes in ECF volume

Front 16

Homeostatic responses to sodium changes

Back 16

- ADH: control of water loss/retention by kidneys and thirst
- Fluid exchange between ECF and ICF

Front 17

Hyponatremia

Back 17

- Low ECF sodium concentration
- Can occur from overhydration or inadequate salt intake
- decrease sodium = decrease water

Front 18

Hypernatremia

Back 18

- High ECF sodium concentration
- Commonly from dehydration
- increased sodium = increased water

Front 19

Steps involved to correct minor sodium level rise in ECF

Back 19

1) Homeostasis disturbed (increased NA+ in ECF)
2) Osmoreceptors in hypothalamus stimulated
3) ADH secretion increases (restricts water loss, promotes thirst)
4) Water shifts out of ICF into ECF reducing sodium concentration in ECF
5) Homeostasis restored

Front 20

Steps involved to correct minor sodium level decrease in ECF

Back 20

1) Homeostasis disturbed (decrease NA+ level in ECF)
2) Osmoreceptors in hypothalamus inhibited
3) ADH secretion decreases (suppress thirst, promotes water loss at kidneys)
4) Water loss reduces ECF volume and sodium concentration increases
5) Homeostasis restored

Front 21

When extreme changes in ECF volume caused by disturbances in sodium balance occur what is activated?

Back 21

- Homeostatic mechanisms activated that control blood volume and blood pressure

Front 22

Steps involved to correct extremly high sodium levels in ECF

Back 22

1) Homeostasis disturbed (rising ECF volume by fluid and/or sodium gain)
2) Increased blood volume and atrial distension
3) Natriuretic peptides released by cardiac cells
4) Increased sodium loss in urine, increased water loss in urine, reduced thirst, inhibits release of ADH, aldosterone, epinephrine and norepinephrine
5) Reduced blood volume and blood pressure
6) Falling ECF volume
7) Homeostasis restored

Front 23

What effect does aldosterone have?

Back 23

- Release = conserve sodium (results in increased water retention)
- Inhibit = release sodium (results in decreased water retention)

Front 24

Potassium Balance

Back 24

- Major gains occur during absorption in the digestive tract
- Major losses occur at the kidneys

Front 25

What organs are primarily responsible for regulating the potassium ion concentration level in the ECF?

Back 25

- Kidneys: controlled by aldosterone regulating Na+/K+ exchange in DCT and collecting duct of the nephron.
**Low pH can cause H+ to be substituted for K+

Front 26

Is potassium usually higher in the ICF or ECF? Why?

Back 26

- Potassium is usually higher in the ICF due to the NA+/K+ pump

Front 27

Hypokalemia

Back 27

- Low potassium levels
- Can be caused by: diuretics, aldosteronism (excessive aldosterone secretion)
- Symptoms: muscular weakness, followed by paralysis

Front 28

Hyperkalemia

Back 28

- High potassium levels
- Can be caused by: chronically low pH (H+ being substituted for K+ at Na+/K+ pumps), kidney failure, drugs promoting diuresis (urine production) by blocking Na+/K+ pumps)
- Symptoms: muscular spasm including heart arrhythmias

Front 29

Acid base balance

Back 29

- H+ production = H+ loss

Front 30

How is H+ gained?

Back 30

- CO2 (to carbonic acid) from aerobic respiration
- Lactic acid from glycolosis

Front 31

How is H+ lost?

Back 31

- Respiratory system eliminates CO2
- H+ excretion from kidneys

Front 32

How is H+ stored?

Back 32

- Buffers temporarily store H+

Front 33

3 Classes of acids

Back 33

- Fixed acids: do not leave solution, remain in body fluids until kidney excretion
- Organic acids: participants or bi-products of cellular metabolism. Metabolized rapidly = no accumulation
- Volatile acids: can leave the body by entering the atmosphere at the lungs

Front 34

Acidemia

Back 34

- Acidic
- Acidosis = physiological state
- More common
- Effects: CNS function deteriorates, cardia contractions are weak and irregular, decreased BP

Front 35

Alkalemia

Back 35

- Basic
- alkalosis = physiological state
- dangerous but rare

Front 36

What is the most important factor affecting body pH?

Back 36

- CO2 partial pressure

Front 37

What happens to pH when CO2 levels rise?

Back 37

- More carbonic acid forms
- Additional H+ and bicarbonate ions are released and pH goes down (acidic)

Front 38

What happens to pH when CO2 levels drop?

Back 38

- Carbonic acid dissociates into carbon dioxide and water which removes H+ ions from solution and increases the pH (basic)

Front 39

What is a buffer?

Back 39

- Substance that opposes changes to pH by removing or adding H+

Front 40

What are the 3 major body buffer systems?

Back 40

- Protein buffer system
- Phosphate buffer system
- Carbonic acid bicarbonate buffer system

Front 41

Metabolic acid-base disorder

Back 41

- Production or loss of excessive amounts of fixed or organic acids
- Carbonic-acid bicarbonate system works to counter

Front 42

Respiratory acid-base disorders

Back 42

- Imbalance of CO2 generation and elimination
- Must be corrected by depth and rate of respiration changes

Front 43

What is metabolic acidosis?

Back 43

- Develops when large numbers of H+ are released by organic or fixed acids
- Accommodated by respiratory and renal responses

Front 44

Metabolic acidosis respiratory and renal responses

Back 44

- Respiratory: increased respiratory rate lowers PCO2 (=H+ + HCO3- -->H2CO3 --> H2O + CO2)
- Renal: occurs in PCT, DCT and collecting duct, H+ secreted into urine, HCO3- reabsorbed into ECF (= H2O + CO2 -->H2CO3 --> H+ + HCO3-)

Front 45

What is metabolic alkalosis?

Back 45

- Develops when large numbers of H+ are removed from body fluids
- Kidney H+ secretion declines
- Collecting system transports bicarbonate into urine and retains acid in ECF
- Accommodated by respiratory and renal responses

Front 46

Metabolic alkalosis respiratory and renal responses

Back 46

- Respiratory: Decreased respiratory rate raises PCO2 (= H2O + CO2 -->H2CO3 --> H+ + HCO3-)
- Renal: occurs in PCT, DCT and collecting duct, HCO3- secreted into urine (in exchange for Cl-), H+ actively reabsorbed into ECF (= H2O + CO2 -->H2CO3 --> H+ + HCO3-)

Front 47

What is respiratory acidosis?

Back 47

- CO2 generation outpaces rate of CO2 elimination at lungs
- Shifts bicarbonate buffer system toward generating more carbonic acid (= H2O + CO2 -->H2CO3 --> H+ + HCO3-)
- HCO3- goes into bicarbonate reserves
- H+ must be neutralized by any of the buffer systems:
--Respiratory (increased respiratory rate), renal (H+secreted, HCO3- reabsorbed), Proteins (bond to free H+)

Front 48

What is respiratory alkalosis?

Back 48

- CO2 elimination at lungs outpaces CO2 generation rate
- Shifts bicarbonate buffer system toward generating more carbonic acid
- (=H+ + HCO3- -->H2CO3 --> H2O + CO2) , H+ removed as CO2 exhaled and water formed
- Buffer system responses:
--Respiratory (increased respiratory rate), renal (H+secreted, HCO3- reabsorbed), Proteins (bond to free H+)

Front 49

How does pH affect respiratory rate?

Back 49

- decreased pH = increased respiratory rate
- increased pH = decreased respiratory rate