Physiology

Question 1

What is the formula for Total Body Water?

Answer 1

TBW=ECF+ICF+ luminal fluid =.60 x body weight in kg.

Question 2

What is ECF composed of?

Answer 2

3/4 ISF and 1/4 plasma

Question 3

What happens if there is excessive loss of luminal fluid? E.g. losing dilute sweat

Answer 3

Higher salt, smaller compartment of ECF, ICF will decrease to balance it out. ECF and ICF osmolality increases.

Question 4

What is the distribution of Na+, K+, Cl- in body compartments?

Answer 4

• Na+ is half in bone/other and half in ECF
• K+ is mostly in ICF
• Cl- is mostly in ECF

Question 5

What is ECF volume determined by?

Answer 5

Sodium.

Question 6

What happens when excess salt is added to the diet (ignoring thirst)?

Answer 6

Osmolality increases, water moves to the ECF. ECF vol increases, ICF vol decreases.

Question 7

What happens if there is a loss of isotonic fluid? e.g. blood loss

Answer 7

osmolality remains the same. ECF volume decreases

Question 8

What happens after you drink a lot of water after excess salt intake?

Answer 8

Osmolality decreases. Volume in ECF decreases and in ICF increases (returns to original state)

Question 9

Describe the Na, K- ATPase transport system?

Answer 9

Na pump moves Na out and K in.

Question 10

A person has diarrhea and has low bicarbonate levels might have …?

Answer 10

Metabolic acidosis

Question 11

How does the body respond to metabolic acidosis?

Answer 11

-want to decrease CO2–>hyperventilation to lose more CO2

Question 12

A person with COPD is short of breath and is not expelling enough CO2 may have…?

Answer 12

respiratory acidosis.

Question 13

How does the body respond to respiratory acidosis?

Answer 13

-metabolic compensation by increasing acid output and bicarbonate reabsorption

Question 14

What can cause metabolic alkalosis?

Answer 14

• vomiting, gastric suction for loss of acid

- over ingestion of base

Question 15

How does the body respond to metabolic alkalosis?

Answer 15

Hypoventilation to increase CO2

Question 16

What can cause respiratory alkalosis?

Answer 16

Hyperventilation causing loss of CO2

Question 17

How does the body respond to respiratory alkalosis?

Answer 17

Decrease renal output of acid and renal reabsorption of bicarbonate

Question 18

What are some extracellular buffers?

Answer 18

bicarbonate, CO2, plasma proteins, inorganic phosphate

Question 19

What are some intracellular buffers?

Answer 19

bone, proteins, organic and inorganic phosphates

Question 20

What senses low or high Na mass/volume in the body?

Answer 20

stretch receptors in the atria/cardiovasculature and baroreceptors in cariovasculature

Question 21

How does the body respond to low sodium mass/volume?

Answer 21

Increase sodium and volume reabsorption by kidney

Question 22

How does the body respond to high sodium mass/volume?

Answer 22

inhibit renal sodium and volume reabsorption, increase urine output

Question 23

What are the organ systems that help control potassium levels in the body?

Answer 23

gut-senses levels

• muscle-potassium stores, releases K when levels are low
• kidney-excretes K when levels are high

Question 24

What organ systems are responsible for maintaining osmolality?

Answer 24

-brain senses osmolality
-kidneys: dilution or concentration of urine output
-brain regulates thirst output
(vasopression from pituitary=anti diuretic)

Question 25

What organ systems are responsible for maintaining glucose levels?

Answer 25

pancreas-senses ECF glucose, amino acids, and fatty acids. And releases insulin liver-releases glucagon

Question 26

How does the cholera toxin cause diarrhea?

Answer 26

It inhibits Na/H antiporter in intestinal villus cells. Activates chloride efflux through Cl channels.-->reduction of NaCl reabsorption, increase in Cl- secretion leads to diarrhea.

Question 27

How is hyponatremia?

Answer 27

-brain and skull swelling due to excessive water intake

Question 28

What can loss of excessive dilute sweat and ptyalism (excess saliva) do to ICF, ECF?

Answer 28

Decreases ICF and ECF volume, increases osmolality.

Question 29

What does intestinal loss of isotonic NaCl do to ICF and ECF volume and osmolality?

Answer 29

ECF volume decreases ICF volume stays same osmolality statys the same.

Question 30

What is conductance determined by?

Answer 30

The number of open ion channels in the cell membrane

Question 31

What generates voltage differences across membranes?

Answer 31

Different rates of ion diffusion due to difference in size of hydrated ions

Question 32

What does the chord conductance equation measure?

Answer 32

Membrane potential as weighted average of equilibrium potential of each indiv ion

Question 33

Define equilibrium potential difference?

Answer 33

Difference in voltage is that is equal to difference in concentration.

Question 34

What is the mechanism behind high NaCl in sweat of patients with CF?

Answer 34

Defects in Cl channel that reduces membrane permeability to Cl- ions. Cl- not reabsorbed from sweat in sweat glands and Na+ does not follow.

Question 35

What are types of passive transport?

Answer 35

Voltage gated, ligand gated, ion channels

Question 36

What is primary active transport?

Answer 36

E.g. Na+/K -ATPase, requires ATP to pump against electrochemical gradient

Question 37

What is secondary active transport?

Answer 37

Uses potential energy stored in sodium gradient to move Na +another solute across the membrane. E.g. symport: Na/glucose antiport: Na/Ca2+, Na+/H+

Question 38

What are cardiac glycosides?

Answer 38

class of drugs that inhibit Na/K ATPase, includes digitalis and ouabain.

Question 39

What is the mechanism behind CFTR defects in the pancreas?

Answer 39

- Cl-/HCO3- exchanger-Cl- enters the cell (bicarb out) and Cl- recycled out the cell through CFTR - In CF, pancreatic ducts can't secrete enough NaHCO3 and water because Cl- is not being recycled out the cell - pancreatic ducts become clogged

Question 40

How is tracheal epithelia affected in patients with CF? how can it be treated?

Answer 40

- NaCl and water absorption is higher-->airway dehydration - trachea epithelia normally have both absorptive and secretory functions - a drug can inhibit epithelial absorption of NaCl and water without affecting secretory function to promote water retention in trachea

Question 41

What is the major pathways of sodium entry across the apical membrane of absorptive epithelia?

Answer 41

- Na Channel - Na/H antiport - Na/K/2Cl symport - Na/Solute co transport

Question 42

What are the mechanisms of chloride entry across apical membranes?

Answer 42

- Cl channel - Na/K/2Cl symport - Cl/HCO3 antiport