Unit 5

Cardiovascular System

Introduction A. The cardiovascular system consists of the heart and three types of blood vessels.

- arteries- capillaries- veins

B. A functional cardiovascular system is vital for supplying oxygen and nutrients to tissues and removing wastes from them.

C. Deoxygenated blood is carried by the pulmonary circuit to the lungs, while the systemic circuit sends oxygenated blood to all body cells.

Structure of the Heart

A. The heart is a hollow, cone-shaped, muscular pump within the thoracic cavity.

B. Size and Location of the Heart 1. The average adult heart is 14 cm long and 9 cm wide.

2. The heart lies in the mediastinum under the sternum; its apex extends to the fifth intercostal space.

Structure of the Heart

Remember the perimysium?

C. Coverings of the Heart1. The pericardium encloses the heart.2. It is made of two layers: the outer, tough connective tissue fibrous pericardium surrounding a more delicate visceral pericardium (epicardium) that surrounds the heart.

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Structure of the Heart

D. Wall of the Heart

1. The wall of the heart is composed of three distinct layers.

- epicardium

- myocardium

- endocardium (the endocardium contains the Purkinje fibers)

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What are Purkinje Fibers?

• Located in the inner ventricular walls of the heart, just beneath the endocardium. These fibers are specialized myocardial fibers that conduct an electrical stimulus or impulse that enables the heart to contract in a coordinated fashion.

Chambers of the HeartChambers of the Heart

• The heart contains four The heart contains four compartments called compartments called chamberschambers..

• The two upper chambers The two upper chambers are called the right and are called the right and left left atriumsatriums..

• The two lower chambers The two lower chambers are called the right and are called the right and left left ventriclesventricles, they are , they are separated by a separated by a septum septum with anwith an apex apex at the base.

Atrium

Atrium

Ventricle

Ventricle

Anatomy of the HeartAnatomy of the Heart

• The atrioventricular valves (AV valve) separate the atrium and ventricle on each side of the heart.

• The AV valves have flaps of tissues, called leaflets or cusps, which open and close to ensure that the blood flows only in one direction and does not backflow into the atriums.

Anatomy of the HeartAnatomy of the Heart

• The AV valve on the right side of the heart is called the tricuspid valve because it has three leaflets (cusps).

• The AV valve on the left side of the heart is called the bicuspid valve (or mitral valve) because it has two leaflets.

Atrium

Atrium

Ventricle

Ventricle

Bicuspid ValveTricuspid

ValveSeptu

m

Apex

Blood Vessels

• The blood vessels form a closed tube that carries blood away from the heart, to the cells, and back again.

– Arteries/Arterioles– Capillaries– Veins/Venules

ArteriesArteries• Arteries – Blood vessels that carry blood Arteries – Blood vessels that carry blood away from the away from the

heartheart. They have . They have thick, elasticthick, elastic walls made of connective walls made of connective tissue and smooth muscle tissue.tissue and smooth muscle tissue.

Main Arteries Connected to the Main Arteries Connected to the HeartHeart

• The right ventricle of the The right ventricle of the heart is connected to the heart is connected to the pulmonary arterypulmonary artery (moves (moves blood toward the lungs).blood toward the lungs).

• The left ventricle of the The left ventricle of the heart is connected to the heart is connected to the aortaaorta (move blood toward (move blood toward other body tissues).other body tissues).

Atrium

Atrium

Ventricle Ventricl

e

Aorta

Pulmonary Artery

ArteriesArteries

• As the arteries extend away from the heart, they branch out into smaller arteries called arterioles.

• The smaller arteries’ walls are composed of large amounts of smooth muscle instead of the elastic tissue.

• Arterioles branch into smaller vessels called capillaries.

CapillariesCapillaries

• Capillaries – Arteries and veins are Capillaries – Arteries and veins are connectedconnected by by microscopic blood vessels. The walls of microscopic blood vessels. The walls of capillaries are only capillaries are only one cell thickone cell thick. Nutrients and . Nutrients and oxygen oxygen diffusediffuse from body cells into capillaries. from body cells into capillaries.

Capillaries• The semi-permeable membrane of capillary

walls allows nutrients, oxygen, and water to diffuse from the blood to the tissues.

• Waste products, like carbon dioxide, diffuse from the tissues into the blood.

Capillaries

• Once blood passes through the capillary beds, it begins its return to the heart.

• Capillaries unite to form small veins called venules.

• The venules join together to form larger veins, which have thin walls and are collapsible.

Blood VesselsBlood Vessels

• Veins – Blood vessels that carry Veins – Blood vessels that carry blood back blood back to the heartto the heart. Veins have one-way valves that . Veins have one-way valves that keep blood moving toward the heart.keep blood moving toward the heart.

Main Veins that are Connected to Main Veins that are Connected to the Heartthe Heart

• The The superior vena cavasuperior vena cava returns blood from your returns blood from your head and neck.head and neck.

• The The inferior vena cavainferior vena cava returns blood from your returns blood from your abdomen and lower abdomen and lower body.body.

Atrium

Atrium

Ventricle Ventricl

e

Inferior Vena Cava

Superior Vena Cava

Main Veins that are Connected to Main Veins that are Connected to the Heartthe Heart

• Right and left Right and left pulmonary veinspulmonary veins bring bring blood from lungs back blood from lungs back to the heart. to the heart.

RightAtrium

LeftAtriu

m

RightVentricl

e

LeftVentricl

e

Pulmonary VeinsPulmonary

Veins

Veins• Veins have valves that aid the return flow of blood and

prevent the blood from reversing flow.

• These valves allow for muscle contractions and movement of body parts.

• The valves also assist the return flow of blood to the heart when blood pressure is low.

RightAtrium

LeftAtriu

m

RightVentricl

eLeft

Ventricle

Pulmonary VeinsPulmonary

Veins

Inferior Vena Cava

Superior Vena Cava Aorta

LeftPulmonary

Artery

Bicuspid ValveTricuspid

ValveSeptu

m

Apex

Aortic Valve

PulmonaryValve

RightPulmonary

Artery

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The Largest Heart and Blood Vessels

Parts of the Circulatory System

The total circulatory system is divided into two main parts:

• Pulmonary circulation

• Systemic circulation

Pulmonary Circulation System

Red portion of heart and red blood vessels carry oxygen-rich blood.

Blue portion of heart and blue blood vessels carry oxygen-poor blood.

Pulmonary circulation:

takes the blood from the heart to the lungs

blood is oxygenated, then its returned to the heart

The main parts of the pulmonary circulation system include the:

- Heart- Pulmonary Arteries- Pulmonary Veins- Alveolar Capillaries

Pulmonary Circulation Pulmonary Circulation

Pulmonary Circulation Pulmonary Circulation

Oxygen Poor Blood

Oxygen Rich Blood

Picks up oxygen from the LUNGS

1. Unoxygenated blood enters the right atrium:

-From upper body via superior vena cava

-From lower body via inferior vena cava.

Flow of Blood in Pulmonary Circulation

2. From atrium, blood goes thru tricuspid valve into right ventricle.

3. Ventricle contracts, pushed blood into pulmonary artery.

4. Pulmonary artery branch apart, sending blood to the right or left lung.

Flow of Blood in Pulmonary Circulation

5. At lung, blood becomes oxygenated by diffusion between the alveoli and capillaries.

Flow of Blood in Pulmonary Circulation

Flow of Blood in Pulmonary Circulation

6. Oxygenated blood goes back to the heart through the pulmonary vein.

- Pulmonary veins returns blood into the left atrium.

The Flow of Blood Through the Systemic Circulatory System

Systemic Circulation:Systemic Circulation: takes takes oxygen-rich bloodoxygen-rich blood from from heart to all heart to all organsorgans and body tissues and body tissues

oxygen-poor blood returns to the heart. oxygen-poor blood returns to the heart. This is the largest section of your circulatory This is the largest section of your circulatory system. system.

The main parts of the pulmonary circuit are the:- Aorta - Veins- Capillaries- Arteries

Systemic CirculationSystemic Circulation

Oxygen Rich Blood

Oxygen Poor Blood

Gives Oxygen to Body Cells

1. Oxygenated blood from left atrium goes thru bicuspid valve to left ventricle.

Flow of Blood in Systemic Circulation

2. Ventricle contracts, pushes blood into aorta under high pressure.

Flow of Blood in Pulmonary Circulation

Flow of Blood in Systemic Circulation

3. Aorta sends blood throughout body to be used by all body cells.

- Blood gets filtered in the kidneys.

4. Blood becomes deoxygenated by diffusion in the capillaries.

5. Deoxygenated blood goes back to the heart via the two vena cava.

Flow of Blood in Systemic Circulation

In the pulmonary system, un-oxygenated blood is carried by the pulmonary arteries and oxygenated blood is carried by pulmonary veins.

In the systemic system, arteries carry oxygenated blood and veins carry un-oxygenated blood.

Don’t Forgot…

Coronary Circulation• The left and right coronary arteries immediately branch

from the aorta and carry fresh blood to the heart muscle itself.

• The coronary veins quickly return that blood back to the heart.

Heart Action

A. The cardiac cycle consists of the atria beating in unison (atrial systole) followed by the contraction of both ventricles, (ventricular systole) then the entire heart relaxes for a brief moment (diastole).

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Cardiac Cycle

1. During the cardiac cycle, pressure within the heart chambers rises and falls with the contraction and relaxation of atria and ventricles.

2. When the atria fill, pressure in the atria is greater than that of the ventricles, which forces the A-V valves open.

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Heart Sounds

1. Heart sounds are due to vibrations in heart tissues as blood rapidly changes velocity within the heart.

2. Heart sounds can be described as a "lubb-dupp" sound.

Heart Sounds

3. The first sound (lubb) occurs as ventricles contract and A-V valves are closing.

4. The second sound (dupp) occurs as ventricles relax and aortic and pulmonary valves are closing.

Electrocardiogram1. An electrocardiogram is a recording of

the electrical changes that occur during a cardiac cycle.

a. The first wave, the P wave, corresponds to the depolarization of the atria.

b. The QRS complex corresponds to the depolarization of ventricles and hides the repolarization of atria.

c. The T waves ends the ECG pattern and corresponds to ventricular repolarization.

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What is a Heart Attack

• Heart attacks most often occur as a result of coronary heart disease, in which a waxy substance called plaque (plak) builds up inside the coronary arteries.

• When plaque builds up in the arteries, the condition is called atherosclerosis (ath-er-o-skler-O-sis). The buildup of plaque occurs over many years.

What is a Heart Attack

• Eventually, an area of plaque can rupture (break open) inside of an artery. This causes a blood clot to form on the plaque's surface. If the clot becomes large enough, it can mostly or completely block blood flow through a coronary artery.

• If the blockage isn't treated quickly, the portion of heart muscle fed by the artery begins to die. Healthy heart tissue is replaced with scar tissue. This heart damage may not be obvious, or it may cause severe or long-lasting problems.

Coronary Artery Stint Surgery

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Blood Pressure

• The surge of blood that occurs with ventricular contraction can be felt at certain points in the body as a pulse.

Irregular Heart Rate

• Pulse rate is recorded by an electrocardiogram (EKG). It is a recording of the electrical changes that occur during a cardiac cycle.

Irregular Heart Rate

• Slow Heart Rate– bradycardia

• Rapid Heart Rate– tachycardia

• Blood pressure or hypertension, is the force of blood against the inner walls of blood vessels anywhere in the cardiovascular system, although the term "blood pressure" usually refers to arterial pressure.

Means ARTERY….refers to blood leaving the

heart!

Blood Pressure

Blood Pressure

• Blood pressure is highest as its leaves the heart through the aorta and gradually decreases as it enters smaller and smaller blood vessels (arteries, arterioles, and capillaries)

Blood Pressure

• Arterial Blood Pressure - Arterial blood pressure rises and falls following a pattern established by the cardiac cycle.

a.During ventricular contraction, arterial pressure is at its highest (systolic pressure).

b.When ventricles are relaxing, arterial pressure is at its lowest (diastolic pressure).

Blood Pressure Readings

• Normal blood pressure less than 120/80

• Pre-hypertension 120-139/ 80-89

• High blood pressure (stage 1) 140-159/90-99

• High blood pressure (stage 2) higher than 160/100

Risks of High Blood Pressure

• According to research studies, the risk of dying of a heart attack is directly linked to high blood pressure, particularly systolic hypertension. The higher your blood pressure, the higher the risk.

• Maintaining lifelong control of hypertension decreases the future risk of complications such as heart attack and stroke.

Causes of High Blood Pressure

• Age: The older a person is, the greater the likelihood that he or she will develop high blood pressure,

• Race: African Americans develop high blood pressure more often than Caucasians.

• Socioeconomic status: High blood pressure is found more commonly among the less educated and lower socioeconomic groups.

• Family history (heredity): The tendency to have high blood pressure appears to run in families.

Causes of High Blood Pressure

• Birth control pills (oral contraceptive use): Some women who take birth control pills develop high blood pressure.

• Lack of exercise (physical inactivity): A sedentary lifestyle contributes to the development of obesity and high blood pressure.

• Medications: Certain drugs, such as amphetamines (stimulants), diet pills, etc.

• Gender: Generally men have a greater likelihood of developing high blood pressure than women.

• Obesity: As body weight increases, the blood pressure rises.

• Sodium (salt) sensitivity: Some people have high sensitivity to sodium (salt), and their blood pressure increases if they use it.

• Alcohol use: Drinking more than one to two drinks of alcohol per day.

Causes of High Blood Pressure