Lecture 10: Fluid Balance

Question 1

Where is the highest volume of water located in the body?

Answer 1

brain & kidneys

Question 2

Where is the lowest volume of water located in the body?

Answer 2

teeth

Question 3

Is 60% of water mostly intracellular or extracellular?

Answer 3

intracellular

Question 4

Where is 40% of water found in the body?

Answer 4

• 8% in blood plasma
• 32% in CSF, lymph, eyes, parietal, peritoneal, synovial fluid

Question 5

Is Na+ extracellular or intracellular?

Answer 5

extracellular

Question 6

Is Cl- extracellular or intracellular?

Answer 6

extracellular

Question 7

Is Mg, potassium, & ATP production extracellular or intracellular?

Answer 7

intracellular

Question 8

Where are most of our extracellular proteins found?

Answer 8

blood plasma

Question 9

How do you gain water?

Answer 9

comsumption & metabolism -> 2.5 L

Question 10

How do we lose water?

Answer 10

• ventilation
• sweat
• urine & feces

Question 11

What occurs if water loss exceeds water gain?

Answer 11

solute conc. increase = dehydration

Question 12

What happens when you get thirsty?

Answer 12

• decrease in blood volume & pressure
• increase in plasma osmolarity ->increase heartrate, release of vasopressin, decrease saliva
• water lost from deep tissues

Question 13

What are osmoreceptors?

Answer 13

• transmit signals to hypothalamus
• triggers thirst response
• triggers salivary glands to reduce secretion
• triggers antidiuretic hormone -> vasopressin

Question 14

What is vasopressin?

Answer 14

• reduces blood flow to extremities & increase blood pressure in arterioles
• acts on collecting ducts of nephrons to increase aaquaporins

Question 15

What are 2 diuretics that inhibit vasopressin?

Answer 15

alcohol & caffeine

Question 16

How do dehydrated kidneys secrete renin?

Answer 16

triggered by macula dense of nephron which monitors NaCl conc.

Question 17

What is the role of renin?

Answer 17

• sodium reabsorption
• water retention

Question 18

What is the role of angiotensin?

Answer 18

• increase aldosterone release form adenal cortex
• triggers vasoconstriction

Question 19

What are ACE inhibitors?

Answer 19

block angiotensin -> NO vasoconstriction -> keeps BP low

Question 20

What is the major cation in extracellular fluid?

Answer 20

Na+
* responsible for most osmotic pressure, cell signaling, membrane pot., thermoregulation

Question 21

What is the major cation in intracellular fluid?

Answer 21

K+
* establishes resting membrane pot. in neurons & muscle fibers

Question 22

How are Na+ & K+ levels regulated?

Answer 22

by aldosterone & angiotensin 2 (responds or low Na+ or high K+)

Question 23

hat is the major anion in extracellular fluid?

Answer 23

Cl-
* maintain neutral charge
* plays role in hyperpolarizing neurons
* needed for neutral charge in blood -> chloride shift (when bicarb comes out & Cl- goes in)

Question 24

What maintains blood pH?

Answer 24

HCO3- (bicarb)

Question 25

What are the roles of Ca2+?

Answer 25

• bone, enamel, dentin
• triggers release of neurotransmitters
• muscle contraction -> binds tropin or calmodulin
• triggers clotting factors
• cofactor to enzymes

Question 26

Where is the majority of HPO4 found?

Answer 26

• bones
• phospholipids, nucleotides, & ATP
• buffers