Blood Osmosis and Ultra-Filtration Quiz

Blood Vessels and Fluid Transport

• The transport of water and fluids between intravascular and extravascular spaces is controlled by hydrostatic and oncotic pressures.
• The movement of substances across blood vessels is controlled by diffusion, filtration, and reabsorption.

Blood Composition

• Blood plasma and red blood cells constitute about 6-10% of the body weight.
• Physiological factors that increase blood volume include increased aldosterone secretion and antidiuretic hormone (ADH) secretion.
• Pathological factors that decrease blood volume include hemorrhage and dehydration.

Osmosis and Ultrafiltration

• Ultrafiltration is the filtration of plasma through the capillary wall, driven by hydrostatic pressure.
• Osmosis is the movement of water from an area of high concentration to an area of low concentration through a selectively permeable membrane.

Regulation of Red Blood Cell Volume

• The main function of regulating red cell volume during hemorrhage is to maintain blood viscosity and prevent circulatory shock.
• The primary function of regulating plasma volume by rapid mechanisms is to maintain blood pressure and prevent hypovolemic shock.

Erythrocyte Characteristics

• Erythrocytes are biconcave disks in humans and some other animals.
• In camelids, erythrocytes are elliptical in shape.
• Cholesterol is impermeable to the cell membrane of erythrocytes.
• The plasticity of the cell membrane of erythrocytes allows them to change shape to fit through narrow capillaries.

Blood Cell Functions

• An increased packed cell volume (PCV) indicates dehydration or polycythemia.
• The PCV is the ratio of the volume occupied by the RBCs to the volume of the whole blood.
• Mast cells and basophils release histamine, which increases capillary permeability and attracts neutrophils to the site of inflammation.
• Neutrophils phagocytose bacteria and foreign particles during the inflammatory response.
• Macrophages engulf and digest bacteria and foreign particles during the inflammatory response.
• Monocytes mature into macrophages, which play a key role in the inflammatory response.