Blood Vessel Characteristics lecture study guide

Carries blood to the heart

veins

Most often shown deoxygenated

veins

Has only one layer

Capillary

Usually high in carbon dioxide

Vein

Lowest pressure within

Vein

More circular lumen

Artery

Has valves

Veins

Carries blood away from heart

Artery

Most often both oxygenated and deoxygenated

Capillary

Has a thick muscle layer

Artery

Has many anastomoses

Capillary

Needs help moving blood

Vein

Has sphincters

Capillary

Has the slowest velocity

Capillary

Where exchange of nutrients occurs

Capillary

Most often oxygenated

Artery

Has two elastic layers

Artery

Highest pressure within

Artery

Flatter lumen

Vein

Has a shunt

Capillary

A small artery leading to a capillary bed is called an

Arteriole

A small vein leading away from a capillary bed is called a

Venule

What is function of the tunica intima?

Provides a smooth, low friction surface that allows blood to flow smoothly through the lumen

What are the 2 functions of the tunica media?

- Withstand High blood pressure

- Constrict and dilate vessels

What are the 2 functions of the tunica externa?

Support and protect vessels

What are vasa vasorum and where are they located?

"Vessels of the vessels." tiny arteries and veins Located within the tunica externa

What are the 2 functions of the vasa vasorum?

To nourish the blood vessels with oxygen and nutrients and remove waste

What vessels have the broadest range of pressures because they can vasodilate and vasoconstrict?

Arterioles (pressure drops from 80 to 35 as they regulate flow

What is the upper and lower ranges of pressure in the capillaries?

Upper range: 35 (arterial end)

Lower range: 20 (venous end)

Do you remember why the capillaries have this range?

The higher pressure at the start forces nutrients and oxygen out to the cells, while the lower pressure at the end lets waste and carbon dioxide flow smoothly back into the blood

Since veins have such a low pressure, what are the 3 ways venous blood needs help in returning blood to the heart?

- Skeletal muscle contraction (squeezes veins when you move)

- Valves preventing backflow

- Breathing (inhaling creates low pressure in the chest, pulling blood upward)

What are varicose veins caused by?

- Caused by internal venous valves that becomes weakened, damaged, floppy. Allowing blood to flow backward and pool up in vessel

• Leaking valves due to long periods of standing

- Pregnancy

- Overweight

- Hereditary.

What kind of cells make up a capillary?

Simple squamous endothelial cells

What makes sure these cells can maintain a circular shape?

Pericytes (A thin basement membrane and isolated smooth muscle)

What are 2 benefits of anastomoses?

• Allows blood to reach and supply every individual cell in the body

• Slows down the velocity of blood flow to allow time for diffusion - also provide alternative pathways if one path is blocked

Why do we want the speed of blood flow to be the slowest in the capillaries?

Because of all the anastomoses, we want time to absorb nutrients and get wastes out

What is a sphincter?

A ring shaped muscle that relaxes or tightens to open or close a passage or opening of body

Are precapillary sphincters on the arterial or venous end of the capillary bed?

At beginning, arterial end

If the precapillary sphincters are open, the capillary bed is ______ with blood. This is called _______

Filled, perfusion

If the precapillary sphincters are closed, the capillary bed is ______. This means the capillaries are using a single pathway called a ____. to move blood quickly from artery to vein.

bypassed/empty, vascular shunt

Give a situation when the precapillary sphincters to your intestines would be open:

• After eating a large meal, when your body needs blood in the GI tract to absorb nutrients

Give a situation when the precapillary sphincters to your intestines would be closed:

• During exercise, stress, studying -> blood needs to be diverted to your skeletal muscle or brain instead

Why isn't eating and exercising good to do close together?

• Body gets confused on where to send blood. It tries to split the supply between the digestive system and your working skeletal muscle doing the splits blood flow, leaving muscle with insufficient oxygen/waste removal = severe cramps

How could this also apply to studying?

• If you try to study after eating, your precapillary sphincters will open inside the digestive system to process food. This leaves oxygen-rich blood available for your brain making you feel sluggish.