The HeartGR 12 A

General functions of the cardiovascular system

1. Transports nutrients and oxygen to the cells

2. Removes carbon dioxide and waste products from the cells

3.Carries blood to parts of the body

4. Returns excess tissue fluid to the

circulation

NUTRIENTS

Components of the cardiovascular system

1. Blood – a liquid connective tissue that can transport nutrients, oxygen and waste products

2. Heart – pumps blood

3. Blood vessels – passageways that transport blood

Types of blood vessels

1. Arteries carry blood away from the heart

a. Arteries and branch into smaller vessels called arterioles

2. Capillaries – tiny blood vessels where nutrients and gases are exchanged

3. Veins carry blood back to the heart

a. Small veins are called venules

Label the diagram

General Structure and Functions of the Heart

A. The heart is a specially shaped muscle

1. It is about the size of a fist and contains a 4 chambers

General Structure

A. The heart is surrounded by a serous membrane known as the pericardium

1. The fibrous pericardium is the tough outer layer

General Structure

The parietal pericardium is fused to the inner surface of the fibrous pericardium

General Structure

3. The visceral pericardium is fused to the surface of the heart

General Structure

4. Between the visceral and serous pericardium is a fluid-filled cavity called the pericardial cavity

5. The visceral and parietal pericardium makes up the serous pericardium

General Structure

The heart wall consists of three layers

1. The outer layer, the epicardium, or the visceral pericardium

2. The middle layer, the myocardium, and is cardiac muscle

3. The inner layer, the endocardium is epithelial tissue

General Structure

The heart is located slightly left of the center of the chest

1. The base of the heart is proximal to the head; the apex of the heart is distal

General Structure

There are four chambers in the heart

1. The two upper chambers are called atria (right atrium and left atrium)

General Structure

2. The two lower chambers are called ventricles (right ventricle and left ventricle)

General Structure

3. The chambers on the left are separated from the chambers on the right by a wall called the septum

a. The interatrial septum separates the atria

b. The interventricular septum separates the ventricles

Cardiac Cycle

Heart movements, the cardiac cycle, are divided into two phases

1. Systole is contraction

a. Blood is ejected

2. Diastole is relaxation

a. chambers fill with blood

Cardiac Cycle

Right heart

1. The right atrium is a collecting chamber where blood is returned to the heart after the trip around the body

a. The two large veins that return blood to the right atrium are the superior and inferior vena cava

2. The blood travels from the right atrium through a one-way valve called either the atrioventricular valve (AV valve) or the tricuspid valve, and into the right ventricle

3. When the right ventricle is full of blood, the heart contracts

Cardiac Cycle

The Right Heart, continued

4. The right pulmonary artery goes to the right lung; the left pulmonary artery goes to the left lung

5. Blood then returns to the heart via the left and right pulmonary veins

Cardiac Cycle

a. Pulmonary arteries are the only arteries in the body that carry deoxygenated blood

i. They carry blood away from the heart towards the lungs to become oxygenated

b. Pulmonary veins are the only veins in the body to carry oxygenated blood

i. They collect oxygenated blood from the lungs and return it to the left side of the heart for distribution to the body

Cardiac Cycle

Left heart

1. The pulmonary veins return blood to the left atrium

2. Once the left atrium is full, blood flows through the left AV valve (also called the mitral valve or bicuspid valve) and into the left ventricle

3. The left ventricle squeezes, forcing the mitral valve closed, and ejects blood through the aortic semilunar valve to the ascending aorta and then out to the rest of the body

Cardiac Cycle

D. After the blood is ejected from the ventricles, the heart enters a resting period called diastole

1. The chambers fill with blood during diastole, or the relaxation phase

2. The blood is ejected during systole, or the contraction phase

3. Both atria fill at the same time, both ventricles fill at the same time, and both ventricles eject blood at the same time when the heart contracts

Mechanics of contraction

1. The heart has to contract in a certain way to make sure all blood is squeezed out during each contraction

2. Contraction begins at the apex and travels upward

3. How much pressure the heart squeezes against affects the thickness of the heart

a. Higher pressures are generated in the ventricles to move blood

i. the ventricular walls are thicker than the atrial walls

b. The left side of the heart must pump blood throughout the entire body

(through the systemic circulation), while the right side of the heart

pumps only to the lungs

Mechanics of contraction

Blood Supply to the Heart – The Coronary Arteries

A. A portion of the newly oxygen-enriched blood leaving the heart is diverted from the aorta by the right and left coronary arteries

1. These arteries continuously divide into smaller branches, forming a web of interconnections known as anastomoses, that consistently supply the heart muscle with a rich supply of blood

Blood Supply to the Heart – The Coronary Arteries

B. The right coronary artery provides blood for the right ventricle, posterior portion of the interventricular septum, and inferior parts of the heart

C. The left coronary artery provides blood to the left lateral and anterior walls of the left ventricle and portions of the right ventricle and interventricular septum

• Now, let’s watch a quick video to review.Video: Heart and circulatory system — How they work - MayoClinic.com