Sec 30.4: Blood Vessels and Transport Flashcards
What are the 3 types of blood vessels and what is their role?
Arteries, Veins, and Capillaries; they act as transportation networks for the blood
What do arteries do?
They carry oxygenated blood away from the heart to body cells
Why do arteries need to be strong and flexible?
Because the blood carried is under great pressure
What are the 3 layers that compose the arteries’ thick walls?
The innermost layer consists of endothelium coated with a protein that prevents blood from clotting
The middle layer is a thick band of smooth muscle and elastic fibers
The outer layer consists of connective tissue and elastic fibers
What is the function of elastic fibers?
They allow the arterial wall to expand and contract to help move blood through the arteries
What are arterioles?
They are smaller arteries that contain the same 3 layers but with thinner outer and middle layers.
What do veins do?
They carry deoxygenated blood from the body cells to the heart
What does their structure reflect?
That blood is under less pressure when returning to the heart
How are veins structured?
- have larger diameters and thinner walls than arteries
- contain valves that prevent blood from flowing backwards
- their walls are thinner than arteries and do not expand and contract
How do skeletal muscles help maintain circulation?
They push against veins so valves open and blood moves toward the heart
What are venules?
They are small veins that join larger veins to capillaries
What do capillaries do?
They carry blood between blood cells
What are their walls made of?
Epithelium
How are they strctured?
- They do not contain muscle cells or elastic fibers
- Their one-cell-thick walls allow materials to diffuse into and out of the blood quickly and easily
What happens as a result of high metabolic activity in the lungs, kidneys, liver,etc.?
Capillaries form dense networks called capillary beds that move a great deal of blood into and out of organs
What is blood presure?
It is the force with which blood pushes against the wall of an artery. A healthy blood pressure is 120/70 mm Hg
What is systolic pressure?
It is the top and higher #, and it is the amount of pressure on the walls of an artery when the left ventricle contracts to pump blood through the body.
What is diastolic pressure?
It is the bottom and lower #, and it is the pressure in the artery when the left ventricle relaxes
What does blood pressure depend on?
It depends on how elastic and unblocked the arteries are and on the strength of the heart’s contractions
What happens when the arteries become less elastic or more blocked?
Blood flow is reduced; the heart must pump harder, and blood pressure rises
How does blood pressure rise naturally?
With activity, stress, and strong emotions
What is hypertension?
It is a condition where people have permanently high blood pressure, which can lead to a heart attack or a stroke
When does a heart attack occur?
When the arteries to the heart muscle are damaged or blocked
When does a stroke occur?
It occurs when blood flow to the brain is interrupted
How can you lower blood pressure and reduce the risk of circulatory disease?
By weight loss, proper diet, and exercise, or medications in the extreme condition
What increases the risk of developing circulatory diseases?
Smoking, lack of exercise, excessive weight, long-term stress, and a diet low in fruits/vegetables (high in saturated fats)
What is arteriosclerosis?
It is a circulatory disease where the artery walls become thick and inflexible
What is atherosclerosis?
It is a circulatory disease where blood flow is partially/fully blocked by plaque
What is plaque?
It is a sticky material that collects on the walls of arteries
What can arteriosclerosis and atherosclerosis lead to if untreated?
They can lead to heart attack, stroke, or disease, and they are warning signs of high blood pressure
What is balloon angioplasty?
It is a surgical technique where blocked arteries supplying the heart muscles can be opened by a device threaded into the artery and then inflated to squeeze the obstruction against the wall.
If balloon angioplasty does not work, what can be done then?
Bypass surgery
What is bypass surgery?
It is an operation where a healthy blood vessel from another part of the body (usually the leg) is attached to the artery on either side of the blockage so blood can bypass it.
