heart and blood vessels

blood vessels and homeostasis

Blood vessels help regulate body processes by either dilating (widening) or constricting (narrowing). This changes the amount of blood flowing to particular organs. For example, dilation of blood vessels in the skin allows more blood to flow to the surface of the body. This helps the body lose excess heat. Constriction of these blood vessels has the opposite effect and helps the body conserve heat.

types of blood vessels

There are three major types of blood vessels: arteries, veins, and capillaries. You can see each type in Figure 18.5. You can watch a good video introduction to the three types at this link: MEDIA Click image to the left or use the URL below. URL: Arteries are muscular blood vessels that carry blood away from the heart. They have thick walls that can withstand the pressure of blood pumped by the heart. Arteries generally carry oxygen-rich blood. The largest artery is the aorta, which receives blood directly from the heart. It branches to form smaller and smaller arteries throughout the body. The smallest arteries are called arterioles. Veins are blood vessels that carry blood toward the heart. This blood is no longer under pressure, so veins have thinner walls. To keep the blood moving, many veins have valves that prevent the backflow of blood. Veins generally carry oxygen-poor blood. The smallest veins are called venules. They merge to form larger and larger veins. The largest vein is the inferior vena cava, which carries blood from the lower body directly to the heart. Capillaries are the smallest type of blood vessels. They connect the smallest arteries (arterioles) and veins (venules). Exchange of substances between cells and the blood takes place across the walls of capillaries, which may be only one cell thick.

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how blood flows through the heart

Blood flows through the heart in two paths. Trace these two paths in Figure 18.4 as you read about them below. You can also learn about how blood flows through the heart with this rap: MEDIA Click image to the left or use the URL below. URL: 1. One path of blood in the heart is through the right atrium and right ventricle. The right atrium receives oxygen- poor blood from the body. It pumps the blood into the right ventricle. Then the right ventricle pumps the blood out of the heart to the lungs. This path through the heart is part of the pulmonary circulation. 2. The other path of blood in the heart is through the left atrium and left ventricle. The left atrium receives oxygen-rich blood from the lungs. It pumps the blood into the left ventricle. Then the left ventricle pumps the blood out of the heart to the rest of the body. This path through the heart is part of the systemic circulation.

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structure of the heart

The heart has four chambers, or rooms, which you can see in Figure 18.3. Each chamber is an empty space with muscular walls through which blood can flow. The top two chambers of the heart are called the left and right atria (atrium, singular). The atria of the heart receive blood from the body or lungs and pump it into the bottom chambers of the heart. The bottom two chambers of the heart are called the left and right ventricles. The ventricles receive blood from the atria and pump it out of the heart, either to the lungs or to the rest of the body. Flaps of tissue called valves separate the hearts chambers. Valves keep blood flowing in just one direction through the heart. For example, a valve at the bottom of the right atrium opens to let blood flow from the right atrium to the right ventricle. Then the valve closes so the blood cant flow back into the right atrium.

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blood vessels

Blood vessels are long, tube-like organs that consist mainly of muscle, connective, and epithelial tissues. They branch to form a complex network of vessels that run throughout the body. This network transports blood to all the bodys cells.

how the heart beats

To move blood through the heart, cardiac muscles must contract in a certain sequence. First the atria must contract, followed quickly by the ventricles contracting. This series of contractions keeps blood moving continuously through the heart. Contractions of cardiac muscles arent under voluntary control. They are controlled by a cluster of special cells within the heart, commonly called the pacemaker. These cells send electrical signals to cardiac muscles so they contract in the correct sequence and with just the right timing.

diseases of the cardiovascular system

Diseases of the heart and blood vessels are called cardiovascular diseases. The leading cause of cardiovascular disease is atherosclerosis. Atherosclerosis is a condition in which a material called plaque builds up inside arteries. Plaque consists of cell debris, cholesterol, and other substances. As plaque builds up in an artery, the artery narrows, as shown in Figure If plaque blocks coronary arteries that supply blood to the heart, coronary heart disease results. Poor blood flow to the heart may cause chest pain or a heart attack. A heart attack occurs when the blood supply to part of the heart muscle is completely blocked so that cardiac muscle cells die. Coronary heart disease is the leading cause of death in U.S adults.

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cardiovascular health

Diseases of the cardiovascular system are common and may be life threatening. A healthy lifestyle can reduce the risk of such diseases developing.

the heart

The heart is a muscular organ in the chest. It consists mainly of cardiac muscle tissue. It pumps blood by repeated, rhythmic contractions. This produces the familiar lub-dub sound of each heartbeat. For a good video introduction to the heart and how it works, watch this entertaining Bill Nye video: MEDIA Click image to the left or use the URL below. URL:

keeping the cardiovascular system healthy

Many factors influence your risk of developing cardiovascular diseases. Some of these factors you cant control. Older age, male gender, and a family history of cardiovascular disease all increase the risk and cant be controlled. However, you can control many other factors. To reduce the risk of cardiovascular disease, you can: avoid smoking. get regular physical activity. maintain a healthy percent of body fat. eat a healthy, low-fat diet. get regular checkups to detect and manage problems such as high blood pressure and high blood cholesterol.

instructional diagrams

No diagram descriptions associated with this lesson

questions

Which blood vessels carry blood away from the heart?

-->  a. arteries

b. veins

c. venules

d. two of the above

__disorder that occurs when plaque blocks coronary arteries

a. right atrium

b. pacemaker

c. left ventricle

d. heart attack

e. right ventricle

f. left atrium

-->  g. coronary heart disease

__chamber of the heart that receives oxygen-poor blood from the body

-->  a. right atrium

b. pacemaker

c. left ventricle

d. heart attack

e. right ventricle

f. left atrium

g. coronary heart disease

The left atrium of the heart receives blood from the

-->  a. right ventricle.

b. right atrium.

c. left ventricle.

d. lungs.

The right ventricle pumps blood to the

-->  a. left ventricle.

b. right atrium.

c. right ventricle.

d. lungs.

__chamber of the heart that pumps blood out of the heart to the rest of the body

a. right atrium

b. pacemaker

-->  c. left ventricle

d. heart attack

e. right ventricle

f. left atrium

g. coronary heart disease

__chamber of the heart that receives oxygen-rich blood from the lungs

a. right atrium

b. pacemaker

c. left ventricle

d. heart attack

e. right ventricle

-->  f. left atrium

g. coronary heart disease

Which blood vessels contain valves?

-->  a. veins

b. arteries

c. arterioles

d. capillaries

__event in which blood supply to the heart is blocked so cardiac muscle cells die

a. right atrium

b. pacemaker

c. left ventricle

-->  d. heart attack

e. right ventricle

f. left atrium

g. coronary heart disease

Which factors are associated with an increased risk of cardiovascular diseases?

-->  a. older age

b. female gender

c. low blood pressure

d. two of the above

__chamber of the heart that pumps blood out of the heart to the lungs

a. right atrium

b. pacemaker

c. left ventricle

d. heart attack

-->  e. right ventricle

f. left atrium

g. coronary heart disease

__cluster of cells in the heart that control contractions of cardiac muscles

a. right atrium

-->  b. pacemaker

c. left ventricle

d. heart attack

e. right ventricle

f. left atrium

g. coronary heart disease

Blood in the pulmonary circulation passes through the right and left atria.

-->  a. true

b. false

Each time the heart beats, the ventricles contract first, followed by the atria.

a. true

-->  b. false

Veins must have muscular walls to withstand the pressure of blood pumped by the heart.

a. true

-->  b. false

Arteries generally carry oxygen-rich blood.

-->  a. true

b. false

When blood vessels dilate, it increases the amount of blood they can carry.

-->  a. true

b. false

Blood in an atrium always flows next to

-->  a. a ventricle.

b. an artery.

c. the lungs.

d. a vein.

In the pulmonary circulation, blood flows through the

a. right atrium.

b. right ventricle.

c. lungs.

-->  d. all of the above

The pacemaker controls the beating of the heart with

a. enzymes.

b. hormones.

-->  c. electrical signals.

d. valves.

Tissues that make up blood vessels include

a. muscle tissues.

b. connective tissues.

c. epithelial tissues.

-->  d. all of the above

Muscular blood vessels that generally carry oxygen-rich blood are

a. veins.

-->  b. arteries.

c. capillaries.

d. venules.

The largest vein in the body is the

a. aort

b. arteriole.

-->  c. inferior vena cava.

d. none of the above

Which statement about capillaries is false?

a. The walls of capillaries may be just one cell thick.

b. Capillaries connect arterioles and venules.

c. The exchange of substances between cells and the blood takes place across capillary walls.

-->  d. Capillaries contain valves to prevent the backflow of bloo

Blood flows through the heart in two paths

-->  a. true

b. false

A valve prevents blood from flowing from a ventricle to an atrium.

-->  a. true

b. false

The systemic circulation includes the right atrium and right ventricle.

a. true

-->  b. false

The aorta is a large blood vessel that carries blood to the heart.

a. true

-->  b. false

Veins have thicker walls than arteries.

a. true

-->  b. false

One way that blood vessels help maintain homeostasis is by dilating or constricting.

-->  a. true

b. false

The leading cause of cardiovascular disease is atherosclerosis.

-->  a. true

b. false

diagram questions

No diagram questions associated with this lesson