Unit 2A

Human Form & Function

Body systems

The heart & circulation

Exterior view of the heart

Image created by Patrick Lynch

Pulmonary arteryLeft atriumPulmonary vein

Left ventricle

Right ventricle

Inferior vena cava

Superior vena cava

Aorta

Right atrium

Section through the heart Aorta

Left atrium

Pulmonary vein

Bicuspid valve

Left ventricle

Right atrium

Right ventricle

Inferior vena cava

Superior vena cava

Pulmonary artery

Semilunar valve

Tricuspid valve

Septum

The Miles Kelly Art library, Wellcome Images

The chambersThe heart consists of four muscular

chambers. The two on the LHS are separated

from the two on the right by the septum.

The upper chambers - the atria – receive blood.

The lower chambers - the ventricles – are the pumping chambers.

The chambers

Left atrium

Left ventricle

Right atrium

Right ventricle

Septum

The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)

The blood vesselsAorta

Pulmonary vein

Inferior vena cava

Superior vena cava

Pulmonary artery

The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)

The blood vessels

Carries From To

Vena cava Deoxygenated blood

The body Right atrium

Pulmonary artery

Deoxygenated blood

Right ventricle

The lungs

Pulmonary vein

Oxygenated blood

The lungs Left atrium

Aorta Oxygenated blood

Left ventricle

The body

The valves

Aortic semilunar valve

Bicuspid atrioventricular valve

Pulmonic semilunar

valveTricuspid

atrioventricular valve

Chordae tendinae

The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)

The valvesThe direction of the blood flow is controlled by four valves.

The atrioventricular valves are held in position by strong tendons, the chordae tendinae (tendineae).

The heart sounds – “lubb dubb” – result from the valves snapping shut.

Blood circulation through the heart

To the body

From the lungs

From the upper body

To the lungs

From the lower body

From the lungs

The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)

Heart beatThe heart contains specialised conductive

tissue which regulates the heartbeat.

The sinoatrial node (SA node or pacemaker) is a cluster of specialised cardiac cells in the wall of the right atrium which initiates the heartbeat.

The atrioventricular node (AV node) is the secondary pacemaker which regulates the beating of the ventricles.

Conductive tissue

Sinoatrial (SA) node – the pacemaker

Atrioventricular (AV) node

Perkinje fibres

The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)

The circulatory system

The blood vessels & circulation

The blood vessels

Arteries - muscular blood vessels that carry blood away from the heart.

Arterioles – small arteries that direct blood flow to various tissues.

Capillaries – microscopic blood vessels that connect arterioles and venules. They enable the exchange of substances between blood and surrounding tissues.

Venules – small veins.Veins - blood vessels that

carry blood toward the heart.

Arteries, veins and capillaries

The Miles Kelly Art library, Wellcome Images

Artery

Arteriole

Capillary bed

Vein

Venule

Blood vessels - structure

Arteries & veins have three layers (the tunicae) – the tunica externa, tunica media & tunica interna

Tunica interna (endothelium)

Tunica media

Tunica externa

The Miles Kelly Art library, Wellcome Images

Blood vessels - structure

Arteries Capillaries Veins

Tunica interna Present Present Present

Tunica media Well developed

None Relatively thin

Tunica externa

Relatively thin None Well developed

Arteries and veins

VEIN

ARTERY

Notice the relatively thin wall and large lumen.

Notice the relatively thick, muscular wall and small lumen.

G. Meyer – ANHB, UWA

Veins contain valves to prevent the back flow of

blood

Valve openValve

closed

Section through a vein showing a valve

The Miles Kelly Art library, Wellcome Images

Valve

Capillaries are where the exchange of materials takes place and consist of one layer of cells only

The Miles Kelly Art library, Wellcome Images

A capillary bed

Jean Wade and Linda Sharp, Wellcome Images

Artery Vein

Capillaries

Capillaries

Capillary

G. Meyer – ANHB, UWA L. Slomianka – ANHB, UWA

Medical Art Services, Munich, Wellcome Images

The circulatory system

Double circulation

Humans, like all mammals, have a double circulation:

The systemic circulationand

The pulmonary circulation.

The pulmonary circulation

The pulmonary circulationtakes deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium.

The right ventricle is the pump for the pulmonary circulation.

The systemic circulationThe systemic circulation

takes oxygenated blood from the left ventricle to all the tissues of the body and returns deoxygenated blood to the right atrium.

The left ventricle is the pump for the systemic circulation.

Double circulationLUNGS

Pulmonary circulation

HEART

Systemic circulationOTHER

PARTSOF THEBODY

Pulmonary circulation

LUNGS

Pulmonary circulation

HEART

Left atrium

Rightventricle

Pulmonary vein

Pulmonary artery

Systemic circulation

HEART

Systemic circulation

ALL PARTSOF THEBODY

Left ventricle

Right atrium

AortaVena cava

Major arteries

HEART

Carotid A

Subclavian AAorta

Renal A

Common iliac A

Femoral A

Celiac A

Mesenteric A

The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)

Major veins

Jugular VSubclavian V

Inferior vena cava

Superior vena cava

Renal V

Common iliac V

Hepatic V

HEART

The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)

Study Guide

Read:TEXT BOOKChapter 6Complete:Activity 6.1RQ 1-12