Chapter 20, Lesson 1: General Anatomy of the Blood Vessels

Flashcards from Chapter 20, Lesson 1 of McGraw Hill Anatomy and Physiology, Tenth Edition, by Kenneth S. Saladin.

Blood vessel categories

• Arteries

• Veins

• Capillaries

Arteries

Blood vessel that carries blood away from the heart

Capillaries

Blood vessel that connects small arteries to veins, forming a circuit

Tunics

Vessel wall layers; there are three in total:

• Tunica interna

• Tunica media

• Tunica externa

Tunica interna

The innermost tunic that lines the blood vessel with a selectively permeable barrier and chemical secretions for constriction and dilation

Tunica media

The middle tunic consisting of smooth muscle, collagen, and elastic tissue for strength

Tunica externa

The outermost tunic made of loose connective tissue to connect with other organs as an anchor

Artery classes

Three classes:

• Conducting (elastic or large)

• Distributing (muscular or medium)

• Resistance (small)

Conducting (elastic or large) arteries

The biggest arteries (such as the aorta or common carotid) that expand and recoil with the systole and diastole to regulate pressure

Distributing (muscular or medium) arteries

The arteries that distribute blood to specific organs (such as the brachial, femoral, renal, or spenic)

Resistance (small) arteries

Smaller arteries to smaller areas

Arterioles

The smallest of the resistance arteries with a 200mm diameter

Aneurysm

A weak point in an artery or heart wall that forms a thin-walled, bulging sac that pulses and can rupture or cause pressure

Carotid sinuses

Baroreceptors (blood pressure sensors) in the walls of the internal carotid artery

Carotid bodies

Oval bodies near the branch of common carotids that function as chemoreceptors (chemistry montors) for O₂ and CO₂ respiration rates

Aortic bodies

The one to three chemoreceptors in the aortic arch

Capillaries

The smaller exchange vessels to allow gasses, nutrients, wastes, and hormones pass between blood and tissue fluid

Capillary types

Three types:

• Continuous capillaries

• Fenestrated capillaries

• Sinusoids

Continuous capillaries

The most common capillaries that allow smaller solutes (like glucose) to pass while blocking large molecules (proteins, blood cells, platelets)

Fenestrated capillaries

Capillaries found in organs needing rapid absorption or filtration (kidneys, small intestine) with filtration pores (fenestrations)

Fenestrations

Filtration pores in fenestrated capillaries that only allow very small molecules to pass

Sinusoids

A type of capillary found in the liver, bone marrow, and spleen for irregularly shaped spaces filled with blood, allowing particles to enter circulation

Capilalary beds

Networks of 10 to 100 capillaries - not all are used; 75% of all capillaries are shut down by precapillary sphincters

Precapillary sphincters

Controls flow in capillary beds supplied with blood; relaxation allows flow and contraction constricts entry

Veins

The thin-walled, flaccid vessels that collapse when empty and expand easily for steady, low pressure flow back to the heart

Postcapillary venules

The smallest veins with just a tunica interna, some fibroblasts, and pores for fluid exchange

Muscular venules

Veins that recieve blood from the post-capillary venules up to 1mm in diameter with one to 2 layers of smooth muscle

Medium veins

Veins up to 10mm in diameter with thick tunica media, externa, and interna as a result of venous valves while pumped by skeleta muscles

Varicose veins

The failure of venous valves in the merium veins as a result of blood pooling and distended veins; can happen as a result of hereditary weakness, obesity, and pregnancy

Skeletal muscle pump

Pump that propels venous blood back to the heart using skeletal muscles; found in the gastrocnemius (calves)

Large veins

Veins with a diameter greater than 10 mm with smooth muscle in all three tunics; thick tunica externa - includes the IVC/SVC, pulmonary veins, and internal jugular veins

Hemorrhoids

Varicrose veins of the anal canal