8. unit 2a heart circulation

8/3/2019 8. Unit 2A Heart Circulation

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Unit 2A

Human Form & Function

Body systems

The heart & circulation


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Exterior view of theheart

Image created by Patrick Lynch

Pulmonary

arteryLeft atriumPulmonaryvein

Leftventricle

Rightventricle

Inferiorvena cava

Superior

vena cava

Aorta

Right atrium


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Section through theheart Aorta

Left atrium

Pulmonary vein

Bicuspid valve

Left ventricle

Right atrium

Right ventricle

Inferior vena cava

Superior venacava

Pulmonary artery

Semilunar valve

Tricuspid valve

Septum

The Miles Kelly Art library, Wellcome Images


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The chambers

The heart consists of four muscularchambers.

The two on the LHS are separated

from the two on the right by theseptum.

The upper chambers - the atria

receive blood.

The lower chambers - the ventricles

are the pumping chambers.


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The chambers

Leftatrium

Leftventricle

Right atrium

Right ventricle

Septum

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


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The blood vessels

Aorta

Pulmonaryvein

Inferior vena

cava

Superior venacava

Pulmonary

artery



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The blood vessels

Carries From To

Vena cava Deoxygenatedblood

The body Rightatrium

Pulmonaryartery

Deoxygenatedblood

Rightventricle

The lungs

Pulmonaryvein

Oxygenatedblood

The lungs Left atrium

Aorta Oxygenatedblood

Leftventricle

The body


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The valves

Aortic

semilunarvalve

Bicuspid

atrioventricularvalve

Pulmonic

semilunarvalve

Tricuspidatrioventricular

valveChordaetendinae



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The valvesThe direction of the blood flow iscontrolled by four valves.

The atrioventricular valves are heldin position by strong tendons, thechordae tendinae (tendineae).

The heart soundslubb dubb result from the valves snapping

shut.


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Blood circulation through the heart

To thebody

From thelungs

From the

upperbody

To thelungs

From thelowerbody

From thelungs



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Heart beatThe heart contains specialised conductive

tissue which regulates the heartbeat.

The sinoatrial node (SA node or

pacemaker) is a cluster of specialisedcardiac cells in the wall of the right atriumwhich initiates the heartbeat.

The atrioventricular node (AV node) is thesecondary pacemaker which regulates the

beating of the ventricles.


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Conductive tissue

Sinoatrial (SA)node thepacemaker

Atrioventricular(AV) node

Perkinje fibres



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The circulatory system

The blood vessels &

circulation


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The blood vessels

Arteries - muscular bloodvessels that carry blood awayfrom the heart.

Arterioles small arteriesthat direct blood flow tovarious tissues.


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Capillaries

microscopicblood vessels that connect

arterioles and venules. They

enable the exchange ofsubstances between bloodand surrounding tissues.


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Venules

small veins.

Veins - blood vessels thatcarry blood toward the

heart.


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Arteries, veins and capillaries


Artery

Arteriole

Capillarybed

Vein

Venule


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Blood vessels - structure

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

Tunica interna(endothelium)

Tunica media

Tunica externa



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Blood vessels -structure

Arteries Capillaries Veins

Tunica interna Present Present Present

Tunica media Well

developed

None Relatively thin

Tunicaexterna

Relatively thin None Welldeveloped


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Arteries and veins

VEIN

ARTERY

Notice the

relatively thinwall and largelumen.

Notice therelatively thick,muscular walland small lumen.

G. Meyer

ANHB, UWA


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Veins contain valves toprevent the back flow

of blood

ValveopenValve

closed


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Section through a vein showing avalve


Valve


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



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A capillary bed

Jean Wade and Linda Sharp, Wellcome Images

Artery Vein

Capillaries


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Capillaries

Capillary

G. Meyer

ANHB, UWA L. Slomianka

ANHB, UWA


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Medical Art Services, Munich, Wellcome Images

The

circulatorysystem


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Double circulation

Humans, like all mammals, have a

double circulation:

The systemic circulation

andThe pulmonary circulation.


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The pulmonarycirculation

The pulmonary circulationtakes deoxygenated blood from

the right ventricle to the lungsand returns oxygenated bloodto the left atrium.

The right ventricle is the pumpfor the pulmonary circulation.


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The systemiccirculationThe systemic circulationtakes oxygenated blood from theleft ventricle to all the tissues ofthe body and returnsdeoxygenated blood to the right

atrium.The left ventricle is the pump for

the systemic circulation.


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Double circulationLUNGS

Pulmonary circulation

HEART

Systemic circulationOTHERPARTSOF THEBODY


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LUNGS


HEART

Leftatrium

Rightventricle

Pulmonaryvein

Pulmonaryartery


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Systemic circulation

HEART

Systemic circulation

ALL PARTSOF THEBODY

Left ventricle

Rightatrium

AortaVena

cava

M j i


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Major arteries

HEART

Carotid A

Subclavian AAorta

Renal A

Commoniliac A

Femoral A

Celiac A

Mesenteric A

The Sourcebook of Medical Illustration (The

Parthenon Publishing Group, P. Cull, ed., 1989)


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Major veinsJugular V

Subclavian V

Inferior venacava

Superior venacava

Renal V

Commoniliac V

Hepatic V

HEART



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Study Guide

Read:

TEXT BOOK

Chapter 6

Complete:

Activity 6.1

RQ 1-12

8. unit 2a heart circulation

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