S. MORRIS 2006

Main functions:

1. Transports gases (from the respiratory system), nutrient molecules and waste materials (from the digestive system)

2. Regulates internal temperature and transports chemical substancesthat are vital to health from one part of the body to another

3. Protects against blood loss form injury and against disease-causingmicrobes or toxic substances introduced into the body

Components

1. Heart – muscular organ that pumps blood to lungs and body

2. Blood vessels – system of hollow tubes through which blood moves

Heart + blood vessels = cardiovascular system

3. Blood – fluid that transports nutrients, oxygen, carbon dioxide

Types of circulatory systems:

1. Open circulatory system: blood flows freely within the body cavity and makes direct contact with organs and tissuesex. Invertebrates such as insects, crustaceans

2. Closed circulatory system: keeps blood physically contained withinvessels and separate from other body tissues

The heart

4 chambers (top and bottom, right and left)

Atria: 2 top chambers (atrium) fill with blood returning fromthe body or the lungs

Ventricles: 2 bottom , receive blood from atria and pump it out to the body or the lungs

atria and ventricles separated by a thick muscular wall called septum

Contracts and relaxes rhythmically and involuntarily without becoming tired.

Made up of cardiac muscle.

Keeps blood flowing (by pumping) in one direction and keeps the oxygen-rich blood separate from the oxygen-poor blood.

The Heart

Receives blood coming back from the body and pumps it out to the lungs.

Vena Cavae (2 large blood vessels) open into the right atrium.

Superior Vena Cava collects oxygen-poor blood coming from the tissues in the head, chest, and arms.

Inferior Vena Cava collects oxygen-poor blood from the tissues elsewhere in the body.

The Right Side of the Heart

The oxygen poor blood flows from the right atrium into the right ventricle and then out into the pulmonary trunk.

It then travels to the pulmonary arteries and then onto the lungs for gas exchange.

The pulmonary arteries carry blood from the heart to the lungs and are the only arteries to carry oxygen-poor blood.

Receives oxygen-rich blood from the left and right lungs and pumps it out to the body.

Pulmonary Veins carry oxygen-rich blood from lungs to the left atrium. They are the only veins to carry oxygen-rich blood.

The left atrium pumps blood into the left ventricle where the blood going to the body leaves through the aorta.

The aorta is the largest vessel in the body.

The Left Side of the Heart

Lungs

Body cells

Our circulatory system is a double circulatory system.

This means it has two parts parts.

the right side of

the system

deals with

deoxygenated

blood.

the left side of

the system

deals with

oxygenated

blood.

The heart has four valves inside of it to ensure the blood flows in the correct direction.

Atria and ventricles are separated by atrioventricular valves. Right side is called the tricuspid valve because it has 3 flaps. Left side is called bicuspid valve because it has 2 flaps. (also

called mitral valve)

Other valves are called semilunar valves because of their half-moon shape. They carry blood away from heart (pulmonary arteries and aorta).

Heart Valves

Arteries Carry blood away from the heart Smaller-diameter arteries are called arterioles

Veins Carry blood toward the heart Smaller-diameter veins are called venules

Capillaries Joins the arteries and arterioles with venules and veins.

One-cell thick and facilitate gas exchange.

Blood Vessels

Elastic walls allow artery to expand as a wave of blood flows through it during the contraction of the ventricles and then snap back when the ventricles relax.

When you measure your pulse, you’re feeling the rhythmic expansion and contraction of an artery as blood passes through it.

Arteries

The ARTERY

thick muscle and elastic fibres

Arteries carry blood away from the heart.

the elastic fibres allow the artery to stretch under

pressure

the thick muscle can contract to push the

blood along.

Have thinner walls than arteries and a larger inner circumference.

Veins are less elastic than arteries.

Muscle contractions keep blood flowing through veins (not contraction of the veins).

Have one-way valves to keep blood flowing in one direction (very important in legs because they ensure blood moves up your leg against gravity).

Veins

The VEINVeins carry blood towards from the heart.

thin muscle and elastic fibres

veins have valves which act to stop the blood from going in the wrong direction.

body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel.

The CAPILLARYCapillaries link Arteries with Veins

the wall of a capillaryis only one cell thick

they exchange materials between the blood and other body cells.

The exchange of materials between the blood and the body can only occur through capillaries.

It’s called a double-circulatory system.

Blood is pumped through one circuit between the heart and the lungs and it’s pumped through a second circuit between the heart and the rest of the body.

The Mammalian Circulatory System

The movement of blood from the heart to the lungs and then from the lungs back to the heart.

Heart to lungs carries waste carbon dioxide (blue in the diagram).

As it passes through lungs, gas exchange occurs and carbon dioxide is replaced with oxygen.

Oxygen-rich blood returns to heart (red).

Pulmonary Circulation

The movement of oxygenated blood from the heart to the tissues and organs throughout the body.

After circulating throughout the body the blood returns to the heart carrying waste carbon dioxide from the body’s tissues.

The blood then re-enters pulmonary circulation.

80-90% of your blood is in systemic circulation.

Systemic Circulation

The movement of blood through the heart.

Cardiac Circulation

Temperature regulation

Vasodilation: An increase in blood flow by widening or dilating the vessels

Occurs when the core body becomes hot

Vasoconstriction: decrease in blood flow by narrowing or constricting blood vessels near surface of skin

Helps to conserve heat

Blood pressure As blood passes through the vessels in body, exerts

pressure against the vessel walls

When ventricles contract and force blood into pulmonary arteries and aorta, pressure increases

Systolic: maximum pressure during ventricularcontraction

Diastolic: lowest pressure before the ventriclescontract