Week 1 Renal

Question 1

Water is added to the body by two major sources?

Answer 1

(1) it is ingested in the form of liquids or water in food, which together normally add about 2100 ml/day to the body fluids
(2) it is synthesized in the body by oxidation of carbohydrates, adding about 200 ml/day. These mechanisms provide a total water intake of about 2300 ml/day.

Question 2

Breakdown of the body fluid compartments?

Answer 2

60/40/20/16/4

Question 3

Plasma & interstitial (extracellular) fluids are similar in composition?

Answer 3

Highly permeable capillary membrane
Protein level > in plasma because of low membrane permeability

Question 4

Intracellular Fluid

Answer 4

Separated by cell membrane
Highly permeable to water not electrolytes (semi-permeable)

Question 5

What is the Gibbs Donnan Equilibrium

Answer 5

-when two solutions are separated by a membrane that is permeable to some ions but is not to others an electrochemical equilibrium is established
-electrical and chemical energies on either side of the membrane are equal and opposite to each other

Question 6

Conservation of mass principle

Answer 6

the total mass of a substance after dispersion in the fluid compartment will be the same as the total mass injected into the compartment.
If none of the substance leaks out of the compartment, the total mass of substance in the compartment (Volume B × Concentration B) will equal the total mass of the substance injected

Question 7

Describe the fluid exchange and osmotic equilibrium

Answer 7

-Distribution of fluid between intracellular & extracellular compartments determined by osmotic effect of small solutes.
-Electrolytes or small ions (i.e.: sodium & chloride) determine distribution of fluids across the semi-permeable cell membrane
-Osmotic factors cause fluids to shift between compartments

Question 8

What is the rate of osmosis?

Answer 8

The rate of diffusion of water is called the are of osmosis

Question 9

What is the osmolality?

Answer 9

Osmoles / kg of water

Question 10

What is osmolarity?

Answer 10

Osmoles / liter of solution

Question 11

What is osmosis?

Answer 11

-the net diffusion of water across a selective membrane
-high water concentration to low water concentration

Question 12

What is osmotic pressure?

Answer 12

-refers to the amount of pressure required to prevent osmosis
-Pressure applied in opposite direction of osmosis

Question 13

Total osmolarity of both the interstitial fluid and plasma, and intracellular fluid?

Answer 13

Total osmolarity of each compartment @ 300 mOsm/L

Question 14

Net effect of an isotonic solution?

Answer 14

increase in extracellular fluid volume

Question 15

Net effect of a hypertonic solution?

Answer 15

an increase in extracellular volume (greater than the volume of fluid added), a decrease in intracellular volume, and a rise in osmolarity in both compartments

Question 16

Net effect of a hypotonic solution?

Answer 16

Both the intracellular and the extracellular volumes are increased by the addition of hypotonic fluid, although the intracellular volume increases to a greater extent.

Question 17

What is hyponatremia and what are some conditions that can cause it?

Answer 17

Hyponatremia: excess water and loss of sodium
Conditions that can cause:
-diarrhea and vomiting
-diuretic abuse
-Addisons disease (decreased secretion of the hormone aldosterone, impairs the ability of the kidneys to reabsorb sodium and can cause a modest degree of hyponatremia)
-excess water retention (ADH)

Question 18

Causes of Hypernatremia?

Answer 18

-inability to secrete antidiuretic hormone, which is needed for the kidneys to conserve water. As a result of lack of antidiuretic hormone, the kidneys excrete large amounts of dilute urine (a disorder referred to as“central” diabetes insipidus
-kidneys cannot respond to antidiuretic hormone, causing a type of“nephrogenic” diabetes insipidus.

Question 19

Two general causes of extracellular edema?

Answer 19

1. Abnormal leakage from plasma
   -Excessive capillary filtration rate
   -Filtration dependent on permeability & surface area of capillary
   -Starling factors: hydrostatic pressure & colloid osmotic pressure
   -Histamine release- anaphylaxis
2. Lymphatic failure to return fluids to blood
   -Lymphatic blockage preventing return of proteins to plasma
   -Increased interstitial colloid osmotic pressure
   -Cancer, surgery, infection (filaria nematodes)

Question 20

Abnormal leakage from plasma overview?

Answer 20

Increased capillary filtration coefficient

Increased capillary hydrostatic pressure

Decreased plasma colloid osmotic pressure
Calcium channel blockers primarily arterial dilate compared to venous dilation which can cause edema

Question 21

Edema caused by heart failure?

Answer 21

Blood flow to the kidneys is reduced and this reduced blood flow stimulates secretion of renin, causing increased formation of angiotensin II and increased secretion of aldosterone, both of which cause additional salt and water retention by the kidneys

Question 22

Other causes of extracellular edema?

Answer 22

-Increased capillary pressure
Retention of sodium & water
High venous pressure
-Decreased arteriole resistance
Decreased plasma proteins
Loss of proteins
Failure to produce proteins
-Increased capillary permeability
Immune reactions
Infection & toxins
Burns & ischemia
-Blockage of lymphatic return

Question 23

Safety factors that prevent edema?

Answer 23

1. The safety factor caused by low tissue compliance in the negative pressure range is about 3 mm Hg.
2. The safety factor caused by increased lymph flow is about 7 mm Hg.
3. The safety factor caused by washdown of proteins from the interstitial spaces is about 7 mm Hg.
   Therefore, the total safety factor against edema is about 17 mm Hg.

Question 24

What percentage of cardiac output is the kidneys?

Answer 24

22% (1100ml/min)

Question 25

What is the nephron?

Answer 25

Functional unit of the kidney

Question 26

What are cortical nephrons

Answer 26

Short loops of Henle, extend to outer medulla
Outnumber juxtamedullary nephrons ~7:1

Question 27

What are Juxtamedullary nephrons?

Answer 27

Extend deep into medulla with long loops of Henle
Play a big role in concentrating urine
Few juxtamedullary nephrons

Question 28

Which nephrons comprise the largest percentage in the human kidney?

Answer 28

cortical nephrons

Question 29

Interstitial space compliance is _____________ as a defense mechanism against edema.

Answer 29

low

Question 30

The osmolarity of plasma is primarily due to?

Answer 30

80%: Sodium and chloride

Question 31

Parts of the loop of henle?

Answer 31

consists of a thin descending limb
a thin ascending limb
a thick ascending limb

Question 32

What percent of nephrons are juxtamedullary?

Answer 32

15%

Question 33

The relative amounts of extracellular fluid distributed between the plasma and interstitial spaces are determined mainly by the balance of?

Answer 33

sodium and chloride

Question 34

The greatest blood flow per gram of tissue goes to which organ?

Answer 34

kidney

Question 35

Which value below is closest to normal serum osmolarity?

Answer 35

300