Medicine Exam Questions (1st Stage)

Homeostasis

• Homeostasis refers to the relative constancy of internal environment composition and functions of an organism.
• It involves the maintenance of a stable internal environment despite changes in the external environment.

Blood Composition

• An adult person's body consists of approximately 60% water.
• Intracellular fluid constitutes approximately two-thirds (2/3) of the total body fluid.
• Extracellular fluid constitutes approximately one-third (1/3) of the total body fluid.
• The extracellular compartment includes the interstitial compartment, intravascular compartment, and intracellular compartment.

Cellular Membrane

• The border between intracellular and extracellular compartments is the cellular membrane.
• The border between interstitial and intravascular compartments is the vascular wall.
• Substances that can pass through the cellular membrane of most cells by simple diffusion include oxygen, carbon dioxide, water, lipophilic substances, and some ions.

Capillary Wall

• Substances that can pass through the capillary wall include oxygen, carbon dioxide, water, glucose, ions, and lipophilic substances.

Physicochemical Constants of Homeostasis

• Three essential physicochemical constants of homeostasis that are most strictly maintained are osmotic blood pressure, oncotic blood pressure, and blood pH level.

Osmotic Blood Pressure

• Normal blood osmotic pressure is 280-300 mosm/L.
• Osmotic blood pressure is created by all substances dissolved in blood plasma.
• The main contribution to osmotic blood pressure is made by Na and Cl ions.

Oncotic Blood Pressure

• Normal blood oncotic pressure is 25-30 mm Hg.
• Oncotic blood pressure is created by blood plasma proteins.
• The main contribution to oncotic blood pressure is made by albumins.

pH Level

• Normal arterial blood pH is 7.35-7.45.
• Net diffusion of water through the cellular membrane occurs when there is a difference in osmotic pressure between the sides of the membrane.
• Acidosis occurs when the arterial blood pH is below 7.35, while alkalosis occurs when the arterial blood pH is above 7.45.

Blood Constituents

• Blood constitutes approximately 6-8% of the body mass.
• Normal blood viscosity is 4.5-5.0, while normal blood plasma viscosity is 1.8-2.2.
• Normal hematocrit values in men are 40-49%, while in women they are 36-42%.
• Normal values of red blood cells count in men are 3.9-5.1 x 10^12/L, while in women they are 3.7-4.9 x 10^12/L.

Red Blood Cells

• Red blood cells membrane destruction with release of hemoglobin into blood plasma is called hemolysis.