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Flashcards in Chapter 20 Deck (100)
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Three parts of the blood vessel wall are?

Tunica interna (endothelium) - inner layer

Tunica media - middle layer

Tunica externa- outer layer


This layer lines the inside of the vessel

This layer is simple squamous epithelium overlying a basement membrane

This layer Is a selectively permeable barrier to materials entering or leaving the bloodstream

Tunica interna


This layer is made of smooth muscle, collagen and elastic tissue

This layer strengthens the vessel and changes the diameter of the blood vessel

Tunica media


This layer is made of loose connective tissue

This layer anchors the vessel and provides passage for small nerves, lymphatic vessels and smaller blood vessels

Small blood vessels called vasa vasorum supply blood to the outer wall of larger vessels

Tunica externa


These carry blood away from the heart



There are three types of arteries, what are they?

Conducting (elastic or large) arteries

Distributing (muscular or medium) arteries

Resistance (small) arteries


The aorta, pulmonary trunk, Common iliac, common carotid, and subclavian arteries, are what type of arteries?

Conducting arteries


- These arteries are smaller branches that distribute blood to specific organs

- There Tunica media has layers of smooth muscle allowing vasomotion

Distributing arteries


- Small arteries, the smallest are arterioles (constriction going on)

Resistance arteries


- Short vessels that link arterioles and capillaries

- Each forms a pre-capillary sphincter, which is smooth muscle that encircles the entrance to one capillary and can shut off
blood through the capillary bed


Meta= between


A weak point in an artery or in the heart wall is called a?



These exchange vessels, they are called?



There are three types of capillaries, what are they?

Continuous capillaries

Fenestrated capillaries

Sinusoids (discontinuous capillaries)


- These capillaries are endothelial cells from a continuous tube

- They're found in most tissues

- Small solutes pass-through, but larger particles are held back

- In the brain blood vessel cells are tightly joined in and form the blood brain barrier

- They have pericytes, which are cells with tendrils that wrap around capillaries and regulate permeability, they contribute to
growth and repair

Continuous capillaries


- Cells that have filtration pores

- These pores allow rapid passage of small molecules, but retain larger molecules

- They are found in the kidneys, endocrine glands, small intestine and choroid plexus

Fenestrated capillaries


- Irregular blood-filled spaces

- Found in the liver, bone marrow and spleen

- Endothelial cells are separated by wide gaps so blood cells and proteins can pass through



- Capillaries are organized into networks called these?

- 10-100 capillaries supplied by single metarteriole

- metarteriole Continues as a thoroughfare channel and leads to a venule

- Capillaries branch off proximal end and empty into the distal end

- When sphincters are closed, blood bypasses the capillaries and flows through the thoroughfare channel to the venule

Capillary beds


- These carry blood back to the heart, what are they?

- expand easily to accommodate increased blood volume

- low blood pressure, about 10 mm Hg



There are five types of veins, what are they?

Postcapillary venules

Muscular Venules

Medium veins

Venous sinuses

Large veins


- These are small veins that receive blood from capillaries

- They are porous and also exchange fluid

Postcapillary venules


- These receive blood from postcapillary venules

- Contain one or two layers of smooth muscle

Muscular venules


- Infolding of their tunica interna form venous valves

- Valves keep the blood from dropping down with the pool of gravity

Medium veins


- Veins with thin-walls, large lumen and no smooth muscle

Venous sinuses


- They have smooth muscle in all three tunics

- Venae cavae, pulmonary, internal jugular, and renal veins

Large veins


The flow of blood back to the heart is achieved by five mechanisms, this process is called?

venous return


These Allow blood to flow in only one direction?

Venous valves


There is a venous pressure gradient from venules to the heart favoring the flow of blood to the heart, this is called?

Pressure gradient


Blood from the head and neck returns to the heart by flowing down through large veins, this is called?



In the limbs, the veins are surrounded by muscles which squeeze the blood out of the vein when the muscles contract, this is called?

Skeletal muscle pump


When you inhale the thoracic cavity pressure drops and the abdominal cavity pressure raises putting pressure on the abdominal inferior vena cava and creating a pressure gradient toward the heart, this is called?

Thoracic (respiratory) pump