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Unit 2A Human Form & Function Body systems The heart & circulation
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
