All MCQs

Inflammation recruits defenses and supports repair, but excessive or chronic inflammation can injure tissues and disturb normal function.

Intact skin is a major barrier to pathogen entry. Cuts allow microbes to bypass this first line of defense.

Secretions such as tears and saliva contain antimicrobial substances and wash microbes from surfaces. These are innate barrier defenses.

Leukocyte numbers often rise during infection as the immune system responds to pathogens. Interpretation depends on species and condition.

Different animal groups use body fluids for transport of nutrients, wastes, gases, hormones, or immune components. The exact composition and pathways vary.

Without circulation, internal transport depends on diffusion, which becomes inefficient over long distances. This limits body size and activity.

Large capillary surface area and short diffusion distance maximize exchange of gases, nutrients, and wastes between blood and cells.

Arteriole constriction reduces local perfusion. Less warm blood reaches the tissue, making it cooler and paler.

Vasodilation increases vessel diameter, reducing resistance and often increasing blood flow to a tissue.

Cardiac output is the volume of blood pumped per minute and equals heart rate times stroke volume. It is a core determinant of blood flow.

Blood circulation transports heat within the body. Ectotherms use behavior and circulation to manage body temperature.

The left ventricle pumps oxygenated blood into the aorta and systemic arteries, supplying the body.