The heart is protected by rib cageThe heart is protected by rib cage

• locate between two lungs

• made of cardiac muscle

• protected by pericardium and rib cage

contracts and relaxes continuously to

provide (pumping force)

The mammalian heartThe mammalian heartHeartHeart

Heart – External View

Blood vessel

CardiacMuscle

Coronary artery and

vein

Vertical section of the HeartVertical section of the Heart

Left auricle

Left ventricle

Right auricle

Right ventricle

bicuspidvalve

Valve – prevent back flow of blood from

……………… to ……………..

Arteries

VeinsVeins

To lungsTo body

deoxygenated blood oxygenated blood

Pulmonary arteryAorta

Pulmonary veinsVena

cava

septumtricuspid valve

Semi-lunar valves

Oxygenated blood

Higher oxygen concentration

Lower carbon dioxide

concentration

Deoxygenated blood

Lower oxygen

concentration

Higher carbon dioxide

concentration

Full of Oxygen

Full of carbon dioxide

The cardiac cycleThe cardiac cycle (the sequence of events that takes place in one heart beat)

Auricle

Ventricle

0 0.2 0.4 0.6 0.8s

The heart beats as the cardiac muscles in its wall contracts (systole) and relaxes (diastole).

Auricle

Ventricle

0 0.2 0.4 0.6 0.8s

Auricular systole (0 –0.1s)

contraction of the two auricles, squeezing blood into the ventriclesAV valves (open), semi-lunar valves (close)

Auricle

Ventricle

0 0.2 0.4 0.6 0.8s

Ventricular systole (0.1 –0.4s)

contraction of the two ventricles, forcing blood out of the ventricles into the arteries AV valves (close), semi-lunar valves (open)

Auricle

Ventricle

0 0.2 0.4 0.6 0.8s

Diastole ( 0.4 - 0.8s )

all four chambers relax, allowing blood to flow into the auricles again.AV valves (open), semi-lunar valves (close)

Changes in blood pressure in the heart during one cardiac cycle.

bicuspid valve close

P(V) < P (A)P(V) > P (A)

bicuspid valve open

Heart beat rate = 60 / 0.8 = 75 beats / min

1st heat sound

Heart attackHeart attack

Fatty substances in blood

cover the inner wall of arteries

Plaque is formed and the

arteries become narrower

This reduce the amount of

blood flowing

Normal arteryNormal arteryArtery with fatty depositsArtery with fatty deposits

Formation of blood clotFormation of blood clot

fatty substances

blood flow restricted

(artery blocked by blood clot)

heartheart

Heart attackHeart attack

Same parts of heart muscle get

too little nutrients and oxygen

Heart beat is upset

HEART ATTACK

if coronary artery is blocked

damaged heart muscle