Human Circulatory System

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

HUMAN CIRCULATORY SYSTEM Various organs involved in the human circulatory system are: → Heart → Arteries → Veins → Capillaries In circulatory system, heart acts as a pump to push out blood thru blood vessels. → Arteries → Veins → Capillaries Arteries

→ thick walled → carry blood from heart to all parts of the body → carry oxygenated blood except pulmonary artery → situated deep inside the body.

Veins

→ thin walled → carry deoxygenated blood except vein → present superficial in body → carry blood from body parts to heart.

STRUCTURE OF HEART Shape

– Triangular

Types of muscle

– Cardiac

Size

– Equal to ones clenched fist.

Chambers – 4 2 upper → Atria • Right • Left 2 lower → Ventricles • Right • Left Valves 2 types → AV valves (Atrio ventricular) → Semilunar valves AV valves separate atria from respective ventricles. They are of 2 types: (1) Tricuspid valve (Rt. sided) (2) Bicuspid valve (Lt. sided)

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STEPS … A T C Y P r og r am _______________________________________________________________________________________ Function of valves → To prevent the backflow of blood into atria when ventricles contract to LECTURE NOTES – BIOLOGY

pump blood out of the heart. Outer covering of Heart → Pericardium (a sheath of tissue which protects heart) Functioning of heart Beating of heart circulates blood in the body. Heart beats non – stop due to rhythmic contraction & relaxation of heart muscles. * Two atria contract together & relax together. Two ventricles contract together & relax together. Contraction of 2 atria is immediately followed by contraction of 2 ventricles. See diagram for structure (internal) & function of heart (Double circulation)

Pulmonary Artery (To Lungs) Venacava

Aorta (To Body) Pulmonary Vein (from Lungs)

V3

V4 Right atrium

Left atrium V1

V2 Right Ventricle

Left Ventricle SEPTUM Muscular wall PERICARDIUM

Outlet Value

Inlet Value

V3 = Aortic semi lunar Value

V1 = Tricuspid value

V4 = Aortic semi lunar Value

V2 = Bicuspid Value

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Right Side of Heart

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Left Side of Heart

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STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

Diagram of Human Heart Showing STRUCTURE

+

Functioning of Heart

(3) Pulmonary Artery ( Deoxygenated Blood)

LUNGS

Left Atrium

Right Atrium

(5)

(2)

V1

V2 (1)Vena cava (Deoxygenated Blood)

(3) Pulmonary Artery (Deoxygenated Blood)

Right ventricle

Right ventricle

(5) Aorta (Oxygenated Blood)

Heart Body Organs Diagram Showing Double Circulation in Heart

* Read it stepwise Double circulation = Systemic circulation step 4 – 6 + Pulucuary circulation step 1 – 3 Heart Beat → One complete contraction & relaxation of heart is called a heart beat. 1 t is usually 70 – 72 times/ min. Heart beats faster during exercise to meet the energy requirements of body in this condition. ECG → Electro – Cardio – Gram An instrument which can record electrical changes during heart beat to detect the normalacy of heart beat.

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