health course chapter 12

Section 12.1 Your Cardiovascular System

• Your cardiovascular system, or the circulatory system, consists of your heart, blood vessels, and blood.

Functions of the Cardiovascular System

• The main functions of the cardiovascular system include

• delivering materials to cells• carrying wastes away

• In addition, blood contains cells that fight disease.


• Your heart continually pumps the blood in your blood vessels throughout your body.

Delivering Materials

• Many substances that your body needs dissolve in the blood.


• Your cardiovascular system transports wastes from your cells.

Removing Wastes

• Your blood picks up carbon dioxide and transports it to the lungs, where it is exhaled.


• Your blood contains cells that attack microorganisms that cause disease.

Fighting Disease

• It also contains substances that seal cuts.


• Think of your cardiovascular system as a network of blood vessels with two major loops.

The Heart

• The first loop leads from your heart to your lungs.

• Each time the heart beats, strong cardiac muscles push blood through the blood vessels.

• The second loop circles through to the rest of your body.


• Each side of the heart has two chambers: an upper chamber called an atrium (plural, atria) and a lower chamber, or ventricle.

Structure of the Heart

• The atria receive blood entering the heart.

• Blood flows from the atria to the ventricles, which pump blood out of the heart.


4) Right VentricleThe right ventricle pumps oxygen-poor blood to the lungs.

3) Right AtriumThe right atrium receives blood from the body that is low in oxygen and high in carbon dioxide.

The Heart

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1) Major vessel from upper body to heart

2) Vessels from lung to heart

5) The aorta carries blood from the left ventricle to the body.

6) Vessel from heart to lungs

7) Vessels from lung to heart

8) Left AtriumOxygen-rich blood is carried from the lungs to the left atrium.

9) Left VentricleThe left ventricle pumps oxygen-rich blood from the heart.


• The action of the heart has two main phases.Your Heartbeat

• The rate at which your heart muscles contract is regulated by the pacemaker, a small group of cells in the wall of the right atrium.

• Average heart rate varies from one person to the next and from one situation to the next.

• In the first phase, the heart relaxes and the atria fill with blood.

• In the second phase, the heart contracts and pumps blood.


Blood Vessels• Your heart pumps blood through an extensive

network of blood vessels.• The three main types of blood vessels in your

body are• arteries• capillaries• veins


Blood Vessels

Artery

Artery Cross Section

Layer of cells

Connective tissueSmooth muscle


• Blood vessels that carry blood away from the heart are called arteries.

Arteries

• Most arteries carry oxygen-rich blood.

• The largest artery in the body is the aorta (ay AWR tuh).

• Arteries have thick walls that are both strong and flexible.


• Branching from the smallest arteries are capillaries, the smallest blood vessels in your body.

Capillaries

• As blood flows through the capillaries, oxygen and dissolved nutrients diffuse through the capillary walls and into your body’s cells.

• Capillaries are involved in temperature regulation.


• From the capillaries, blood flows into small blood vessels that join together to form veins.

Veins

• Veins are large, thin-walled blood vessels that carry blood to the heart.


Blood Vessels

Capillary

Capillary Cross Section

Single layer of cells

Vein

Layer of cells

Connective tissueSmooth muscle

Vein Cross Section


• Blood pressure is the force with which blood pushes against the walls of your blood vessels.

Measuring Blood Pressure

• Normal Blood Pressure A blood pressure reading is considered normal if it falls within the range of 90/60 to 119/79.

• Low Blood Pressure Blood pressure lower than 90/60 is considered to be low blood pressure.

• High Blood Pressure A person whose blood pressure is consistently 140/90 or greater has high blood pressure, or hypertension.


• The average adult has about 4 to 6 quarts of blood circulating through his or her blood vessels.

Blood

• The four components of blood are• plasma• red blood cells• white blood cells• platelets


• The liquid component of the blood is called plasma.Plasma

• This straw-colored liquid makes up about 55 percent of the blood.

• Plasma is mostly water, with substances such as nutrients, hormones, and salts dissolved in it.


• The cells that carry oxygen from the lungs to all the parts of your body are red blood cells.

Red Blood Cells

• Red blood cells contain hemoglobin, which is an iron-containing substance to which oxygen binds.


• White blood cells help protect you against diseases and foreign substances.

White Blood Cells

• Some white blood cells make chemicals that help your body resist diseases such as cancer.

• Others destroy invading microorganisms by surrounding and consuming them.


• Platelets (PLAYT lits) are cell fragments that play an important role in the blood clotting process.

Platelets

• When you get a cut, platelets stick to the edges of the cut and release proteins called clotting factors.


• A person’s blood type is determined by the proteins present on the surface of the red blood cells.

Blood Types

• Depending on which proteins are present, a person’s blood type can be type A, B, AB, or O.

• A second blood type is determined by the presence or absence of the Rh factor protein.


• After an injury, surgery, or some illnesses, a person may require a blood transfusion.

Transfusions

• During a transfusion, blood from a donor is transferred to the patient’s bloodstream.


Transfusions

Section 12.2 Cardiovascular Health

• Hypertension and high blood cholesterol are two factors that increase your risk of heart attack and stroke.

Cardiovascular Diseases

• Both factors may begin in your teens.


• A person whose blood pressure is consistently 140/90 or greater has hypertension.

Hypertension

• Hypertension damages blood vessel walls due to the increased force of the blood.

• The heart must work extra hard to pump blood through the body.


• Low-density lipoproteins (LDL) carry cholesterol to body tissues for use or storage.

Blood Cholesterol

• High-density lipoproteins (HDL) pick up excess cholesterol from body tissues and artery walls and carry it to the liver.

• Plaque is a substance that builds up in artery walls.

• Atherosclerosis is a condition in which an artery wall hardens and thickens due to plaque buildup.


• As artery walls thicken, blood flow is constricted.Heart Attack and Stroke

• Some cells may not receive adequate oxygen or a blood clot could block the narrowed artery.

• If the artery carries blood to your heart muscles, a heart attack may result.

• If the artery carries blood to your brain, a stroke may result.


• Heart Murmur is an extra sound, in addition to the lub-dub, a doctor hears when listening to a heartbeat.

Other Cardiovascular Disorders

• Opening in Heart Wall is a hole in the wall separating the two atria. Oxygen-rich and oxygen-poor blood will mix in the heart, reducing its efficiency.

• Arrhythmia is an irregular heartbeat.


• Establishing healthy habits now will decrease your risk of serious health problems in the future.

Keeping Healthy

• exercise regularly• To help maintain cardiovascular health, you should

• eat a nutrient-rich, balanced diet• avoid smoking


ExerciseTeens should spend 60 minutes performing physical activity every day, or at least most days.

• Heart muscles strengthen, allowing more blood to be pumped with each beat.

• Blood pressure may decrease.• HDL levels may increase.• Stress levels may lower.


Diet• No matter how much you exercise, you still need to

pay attention to what and how much you eat.

• To reduce your risk of cardiovascular disease• limit your intake of fried or processed foods and

of foods made from animal products• eat high-fiber foods• limit your salt intake


• Tobacco products damage blood vessels and contribute to the development of atherosclerosis and hypertension.

Avoid Smoking

• Smokers are two to three times more likely to have a heart attack than nonsmokers.

Section 12.3 Respiratory Health

• The respiratory system is responsible for bringing oxygen from the outside environment into the body.

The Respiratory System

• It also removes carbon dioxide from the body.


On its way to the lungs, air passes through theThe Pathway of Air

• nose• pharynx• larynx• trachea• bronchi


The Respiratory SystemNose and Nasal CavitiesAir enters the body through two nostrils and then moves into the nasal cavities.

PharynxNext air enters the pharynx, or throat. The mouth also connects to the pharynx.

Epiglottis and LarynxAir travels from the pharynx to the larynx. The larynx contains the vocal cords. When you swallow, the epiglottis seals the larynx to prevent food or liquid from entering the trachea.

TracheaThe trachea, or windpipe, leads from the larynx to the lungs.

LungIn the lungs, bronchi divide like branches of a tree into smaller tubes. At the end of the smallest tubes are the alveoli. Oxygen and carbon dioxide are exchanged in alveoli.

BronchusThe trachea divides into two bronchi (singular, bronchus), which are cartilage-ringed tubes that enter each lung.

CiliaCilia line most of the respiratory tract. Cilia capture mucus that contains dust and microorganisms and sweep it toward your throat to be swallowed.


• At the end of the smallest tubes in the lungs are millions of tiny sacs that look like bunches of grapes.

Gas Exchange

• These sacs, called alveoli (singular, alveolus), are where gases are exchanged between the air and the blood.


Alveoli

Capillary

Blood rich in carbon dioxide

Blood richin oxygen


The breathing process is controlled by the actions of muscles in your ribs and chest.

The Breathing Process

• Inhalation • When you inhale, the diaphragm (DY uh fram), a dome-

shaped muscle that lies below the lungs, flattens.• The chest cavity enlarges, the volume of the lungs

increases, and air flows in.• Exhalation

• When you exhale, or breathe out, the diaphragm moves upward.

• The rib muscles relax and the ribs drop.• These movements make the chest cavity smaller and

squeeze air from the lungs.


InhalationThe volume of the lungs increases, and air flows in.

ExhalationThe volume of the lungs decreases, and air is pushed out.


You can keep your respiratory system healthy byKeeping Healthy

• avoiding tobacco smoke and air pollution• treating asthma if you have it• avoid respiratory infections• get regular exercise• maintain a healthy weight


• The most important think you can do to protect your respiratory system is not to smoke.

Avoiding Smoking and Air Pollution

• It is also important to avoid exposure to air pollutants whenever possible.

• Before exercising outdoors on a hot, sunny day, check local news reports for warnings about air quality.

• Work in a well-ventilated area when you paint or use other chemicals.

• If you do work that generates fumes or dust wear a mask.


• Asthma (AZ muh) is a disorder in which respiratory passageways become inflamed.

Living With Asthma

• During an asthma attack, the passageways narrow until air can barely pass through.

• As a result, the person wheezes, coughs, and has difficulty breathing.


• Avoid Respiratory Infections Bronchitis is an infection that causes the mucous membranes lining the bronchi to become inflamed.

Other Healthful Behaviors

• Get Regular Exercise Exercise helps your lungs become more efficient at taking in oxygen and eliminating carbon dioxide.

• Maintain a Healthy Weight The respiratory system of an overweight person must work harder to deliver adequate oxygen than the system of a normal weight person.

health course chapter 12

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