The Circulatory System: Blood Vessels and Circulation

This set of flashcards covers key terms and concepts related to the anatomy and physiology of the circulatory system, specifically focusing on blood vessels and circulation.

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that carry blood back to the heart.

Capillaries

Small blood vessels that connect the smallest arteries to the smallest veins, facilitating the exchange of substances.

Tunica interna (tunica intima)

The inner layer of blood vessel walls, consisting of simple squamous epithelium that acts as a selectively permeable barrier.

Tunica media

The middle layer of blood vessel walls composed of smooth muscle, collagen, and elastic tissue; controls blood vessel diameter.

Tunica externa (tunica adventitia)

The outermost layer of blood vessels made of loose connective tissue that anchors the vessel and provides passage for small nerves and lymphatic vessels.

Aneurysm

A weak point in an artery or heart wall that forms a bulging sac that may rupture.

Baroreceptors

Sensory structures in arterial walls that monitor blood pressure and help regulate heart rate and blood vessel diameter.

Chemoreceptors

Sensory structures that monitor blood chemistry and can adjust respiration rates and vascular resistance.

Continuous capillaries

The most common type of capillary with endothelial cells forming a continuous tube with small gaps allowing some solute movement.

Fenestrated capillaries

Capillaries with filtration pores that allow for rapid absorption and filtration, found in organs such as kidneys.

Sinusoids

Irregular capillaries found in the liver, bone marrow, and spleen, permitting the passage of large molecules and cells.

Gross anatomy of veins

Veins are generally thin-walled, flaccid, and can collapse when empty, having a greater capacity for blood than arteries.

Portal system

A system where blood flows through two consecutive capillary networks before returning to the heart.

Hydrostatic pressure

The pressure that drives fluid out of capillaries and is higher at the arterial end compared to the venous end.

Colloid osmotic pressure (COP)

The pressure that draws fluid into capillaries, primarily influenced by plasma proteins.

Capillary exchange

The process of fluid and solute movement across capillary walls facilitating nutrient and waste exchange.

Edema

The abnormal accumulation of excess fluid in tissues, often caused by increased capillary filtration or reduced reabsorption.

Vasomotion

The process of blood vessel contraction (vasoconstriction) and expansion (vasodilation) to regulate blood pressure and flow.

Skeletal muscle pump

A mechanism aiding venous return where contracting muscles compress veins.

Cardiac suction

A mechanism that helps draw blood into the atria during ventricular contraction.

Hypertension

A chronic condition characterized by elevated blood pressure.

Atherosclerosis

A disease characterized by the buildup of lipids in artery walls, leading to reduced blood flow.