Transport in IB Biology HL

Flashcards on Transport in IB Biology HL

Circulatory System

An integral part of maintaining homeostasis by transporting blood, vital nutrients, and important molecules throughout the body.

Capillaries

Primary sites of material exchange (gases, nutrients, and wastes) between the blood and tissues or alveoli.

Capillary Wall Thickness

One-cell thick (only endothelium) to minimize diffusion distance.

Capillary Lumen Diameter

Extremely narrow (just wide enough for a red blood cell) to maximize surface area contact and slowing flow for exchange.

Capillary Branching

Extensive networks (capillary beds) to increase surface area and ensure all cells are near a capillary.

Capillary Fenestrations

Small pores in endothelial cells to facilitate exchange of larger molecules like hormones or plasma proteins.

Arteries

Transport blood away from the heart at high pressure (typically oxygenated except for pulmonary artery).

Veins

Return blood to the heart at low pressure (typically deoxygenated except pulmonary vein).

Arteries Lumen Diameter

Narrow

Veins Lumen Diameter

Wide

Arteries Wall Thickness

Thick

Veins Wall Thickness

Thin

Arteries Wall Layers

3 (tunica intima, media, externa)

Veins Wall Layers

3 (same tunica intima, media, externa)

Arteries Muscle & Elastic Fibers

Abundant (especially in tunica media)

Veins Muscle & Elastic Fibers

Sparse

Arteries Valves

Absent

Veins Valves

Present (prevent backflow)

Arteries Function

Transporting blood away from the heart, under high pressure.

Veins Function

Transporting blood back to the heart, under low pressure.

Arteries Wall Layers

tunica interna (or tunica intima), tunica media, tunica externa

Tunica interna

lines the lumen (inner space) of the blood vessel and provides a smooth surface for blood to flow with low resistance.

Tunica media

Provides support for the vessel and change vessel diameter to regulate blood flow and blood pressure.

Tunica externa

connective tissue with varying amounts of elastic and collagenous fibers that attach the vessel to the surrounding tissue.

Elastic fibers in arteries

allow the artery wall to expand and recoil with each pulse of blood from the heart, propelling the blood towards the capillaries.

Muscle fibers in arteries

can contract and relax to adjust diameter of the artery lumen, regulating blood flow and blood pressure in the vessel.

Vein valves

prevent the backflow of blood.

Coronary arteries

supply oxygenated blood to the heart muscle itself.

Coronary occlusion

is the partial or complete blockage of blood flow in a coronary artery.

Myocardial infarction (MI)

Heart attack

Atherosclerosis

the buildup of cholesterol, fat, and other substances (plaque) inside artery walls.

Thrombosis

the formation of a blood clot (thrombus) within a blood vessel, usually due to the rupturing of a plaque.

Embolism

the movement of a blood clot through narrow blood vessels, blocking blood flow past the clot.

Coronary heart disease (CHD)

the result of the decreased blood flow to the heart muscle due to coronary occlusion.

Epidemiology

the study of the cause and spread of disease in a population.