fluid and electrolytes

Question 1

how much does adult water account for in bodyweight?

Answer 1

60% for males and 50% for females

Question 2

what percentage of water is an infant composed of?

Answer 2

75%

Question 3

what are the two main fluid compartments?

Answer 3

intracellular fluid and extracellular fluid

Question 4

what percentage of water does extracellular fluid account for?

Answer 4

40%

Question 5

what percentage of water does intracellular fluid account for?

Answer 5

60%

Question 6

what percentage of body water is in the plasma?

Answer 6

8%

Question 7

what percentage of body water is in the interstitial fluid?

Answer 7

32%

Question 8

what percentage of body water is in the cytosol?

Answer 8

60%

Question 9

what is the major cation of the ECF?

Answer 9

Na+

Question 10

what is the major cation of the ICF?

Answer 10

K+

Question 11

what is the major anion of the ECF?

Answer 11

Cl-

Question 12

what is the major anion of the ICF?

Answer 12

HPO42-

Question 13

what two tasks are involved to maintain fluid homeostasis?

Answer 13

• maintaining water balance within cells

- maintaining water balance in plasma

Question 14

what is maintained between narrow limits in the ECF composition?

Answer 14

• water balance
• water intake= output
• must maintain solute concentration

Question 15

what are the percentages of water input sources?

Answer 15

• 60% fluids (approx 1500ml)
• 30% food (approx 750ml)
• plus 10% from cellular metabolism

Question 16

what are changes in osmolarity detected by?

Answer 16

osmoreceptors in the hypothalamus

Question 17

what organ primarily controls fluid and electrolyte homeostasis?

Answer 17

kidneys

Question 18

where is the thirst centre located?

Answer 18

hypothalamus

Question 19

what is the hypothalamic thirst centre stimulated by?

Answer 19

• 1-2% change in osmolarity

- 5-10% change in plasma volume

Question 20

what are feedback mechanisms that inhibit thirst?

Answer 20

• moistening of mucosa
• stretch receptors of stomach and intestine
• decrease in osmolarity

Question 21

what does ADH inhibit?

Answer 21

diuresis

Question 22

what does ADH work to do?

Answer 22

maintains electrolyte balance of ECF by conservation of water at kidneys decreasing urine output

Question 23

where is ADH made, stored, and released from?

Answer 23

posterior pituitary

Question 24

where is aldosterone synthesised and secreted by?

Answer 24

adrenal cortex

Question 25

what is aldosterone stimulated by?

Answer 25

angiotensin II plus elevated K+ in ECF

Question 26

what is dehydration?

Answer 26

when water output exceeds water intake

Question 27

what can losses in ECF be due to?

Answer 27

- severe burns - severe vomiting and diarrhea - profuse sweating - low water intake - haemorrhage

Question 28

where is water lost from dehydration?

Answer 28

from ECF

Question 29

what happens to cells during dehydration?

Answer 29

dehydrate and crenate

Question 30

what does dehydration result in?

Answer 30

hypernatremia (high Na+ in ECF)

Question 31

what are the early signs of dehydration?

Answer 31

- increased thirst - dry mucous membrane - dry flushed skin

Question 32

what occurs if dehydration is prolonged?

Answer 32

- confusion, disorientation - hypovolaemia - hypovolaemic shock (esp. hemorrhaging)

Question 33

what is hormonal systems are activated by decreased blood volume and pressure?

Answer 33

- RAAS - aldosterone secretion - ADH secretion - sympathetic NS

Question 34

what is hypotonic hydration?

Answer 34

when water intake exceeds water output

Question 35

when does hypotonic hydration occur?

Answer 35

renal insufficiency and rapid excess water ingestion

Question 36

what does hypotonic hydration result in?

Answer 36

hyponatremia (low Na+ in ECF)

Question 37

what happens to cells during hypotonic hydration?

Answer 37

cells swell and lysis is possible

Question 38

what is oedema?

Answer 38

an abnormal accumulation of fluid in the interstitial space

Question 39

what is caused by?

Answer 39

- increases in capillary hydrostatic pressure - increases in capillary permeability - decreases in colloid osmotic pressure

Question 40

what is lymphoedema?

Answer 40

accumulation of ISF due to surgically removed or blocked lymph glands

Question 41

what is pH regulated by?

Answer 41

- chemical buffer system - respiratory regulation - renal mechanism

Question 42

what is the slowest of the pH regulators?

Answer 42

renal takes hours or days but is the most potent

Question 43

what is a chemical buffer?

Answer 43

a substance that minimises changes in pH by binding or releasing free H+ ions

Question 44

what are the three main chemical buffer systems?

Answer 44

- carbonic acid-bicarbonate ion - phosphate buffer - protein buffer

Question 45

if pH drops does the carbonic acid-bicarbonate buffer system bind or release H+?

Answer 45

bind

Question 46

if pH rises does the carbonic acid-bicarbonate buffer system bind or release H+?

Answer 46

releases

Question 47

does the respiratory regulator of pH have more or less capacity than the chemical buffering system?

Answer 47

more

Question 48

what do the kidneys work to do during renal mechanism of pH?

Answer 48

- remove acids produced by metabolic reactions in the body | - conserve or renew acids when needed

Question 49

what is the renal mechanism able to do?

Answer 49

- conserve HCO3- and generate new HCO3- | - excrete HCO3-

Question 50

will HCO3- be reabsorbed or secreted if pH drops?

Answer 50

reabsorbed

Question 51

will HCO3- be reabsorbed or secreted if pH increases?

Answer 51

secreted

Question 52

will H+ be absorbed or secreted if pH drops?

Answer 52

secreted

Question 53

will H+ be absorbed or secreted if pH increases?

Answer 53

absorbed

Question 54

what is the absolute limit of blood pH?

Answer 54

6.8-7.8 (ideally 7.4)

Question 55

when does respiratory acidosis occur?

Answer 55

when hypoventilation causes retention of CO2 leads to carbonic acid excess and a decrease in pH

Question 56

when does metabolic acidosis occur?

Answer 56

with an excess of fixed acids in the body leads to a decrease in pH