Week 1 - Salt & Water Handling

Question 1

What determines extracellular fluid volume?

Answer 1

Sodium content (total body sodium content)

Question 2

What determines intracellular fluid volume?

Answer 2

Sodium concentration

Question 3

What are some effectors of Na+ regulation?

Answer 3

RAAS
PGs (PGI2)
Renal sympathetic nerves
ANP
NO

Question 4

What is an example of ANP?

Answer 4

Uroguanylin

Question 5

What does increased Na+ content cause?

Answer 5

edema

Question 6

What does decreased Na+ content cause?

Answer 6

Hypovolemia or shock

–> Can lead to low Na+ concentration (via ADH induced H2O retention)

Question 7

What does increased water content cause?

Answer 7

Intracellular edema (due to hyponatremia?)

Question 8

What does decreased water content cause?

This is the least common of Na+/water imbalances

Answer 8

Sudden drop in water content can cause osmotic demyelination (don’t need to know the details of this yet)

Question 9

What is being sensed in Volume Regulation?

Answer 9

Effective circulating volume

Question 10

What is being sensed in Osmoregulation?

Answer 10

Plasma osmolarity - intracellular osmolarity

Question 11

What are the sensors for Volume Regulation? (3)

Answer 11

Carotid sinus
Atria
Renal Circulation

Question 12

What is the sensor for Osmoregulation?

Answer 12

Hypothalamus

Question 13

What are some effectors of Volume Regulation?

Answer 13

Sympathetic Nerves
RAAS
ANP
Pressure Natriuresis
ADH

Question 14

What is the main effector of Osmoregulation?

Answer 14

ADH

Question 15

What is effected in Volume Regulation?

Answer 15

Sodium excretion

Question 16

What is effected in Osmoregulation?

Answer 16

Water excretion (via ADH)
Water intake (thirst)

Question 17

What is the concentrating segment of the nephron? Why?

Answer 17

The descending limb (because water is reabsorbed here)

Question 18

What is the diluting segment of the nephron? Why?

Answer 18

The ascending limb (because Na+ & K+ & Cl- are all being reabsorbed)

Question 19

Where does ADH act?

What does it do?

Answer 19

Collecting duct

Either permits or does not permit reabsorption of water

Question 20

What would cause ADH release to be inhibited?

Answer 20

Drinking a big glass of water

Question 21

What is the sympathetic innervation to the kidneys?

Answer 21

Afferents from T10-L1

Question 22

What is the parasympathetic innervation to the kidneys?

Answer 22

Vagus (CN X)

Question 23

Where is referred kidney pain usually felt?

Answer 23

Dermatomes T10-T12 on the back, “flank pain”

Question 24

Where are the venous sensors for Na+ regulation?

What do they detect?

Answer 24

Right Atrium (detect stretch)
 & Pulmonary Receptors (sense early pulm edema)

Question 25

What happens after the right atrial stretch receptors are activated?

Answer 25

• stimulates release of ANP
• inhibits ADH
• decrease in vascular resistance

Question 26

What are the pulmonary receptors?

What happens when they are activated?

Answer 26

Nerves adjacent to the pulmonary capillaries.

- inhibit SNS

Question 27

What is tonicity?

Answer 27

the effective osmolality

Question 28

What is osmolality?

Answer 28

The amount of osmotically active particles in solution divided by mass of solvent (water)

Question 29

What are effective osmoles?

Answer 29

solutes that cannot move across cell membranes

Question 30

At any given time, what percent of the body’s blood volume is located in the venous system?

Answer 30

70%

Question 31

What are 4 causes of metabolic acidosis?

Answer 31

Ketoacidosis
Lactic acidosis
Renal Failure
Toxins/OD