Transcript The Cardiovascular System

The Cardiovascular System
Learning Outcome
 Show an understanding of the cardiovascular
system
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Describe the structure and function of the heart
Describe the major components of the
circulatory system
Cardiovascular System
 Consists of Heart, Lungs and Vessels
BODY
HEART
Systemic circulation
LUNGS
Pulmonary Circulation
The Heart
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Made of cardiac muscle (myocardium)
Has it’s own blood supply
Two upper thin walled chambers – atria
Two lower thick walled chambers – ventricles
Atria collect blood from the body – attached to
veins
 Ventricles send blood to the body – attached to
arteries
The Heart
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Right side – deoxygenated
Left side – oxygenated
Separated by a thick walled septum
Right atrium and ventricle connected by tricuspid
valve
 Left atrium and ventricle connected by bicuspid
(mitral) valve
 Cuspid valves held shut by Chordae Tendinae
 Left ventricle is thicker than the right
Vessels of the Heart
 Pulmonary artery*
 Pulmonary vein
 Superior and Inferior Vena cava
 Aorta*
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*Semi-lunar valves
Diagram of the Heart
Blood Flow Through the Heart
1.
2.
3.
4.
5.
Vena Cava – Superior/Inferior
Right Atrium
Tricuspid Valve
Right ventricle
Pulmonary Artery
LUNGS
Blood Flow Through the Heart
6. Pulmonary veins
7. Left Atrium
8. Bicuspid/Mitral/Atrioventricular valve
9. Left Ventricle
10. Aorta
MAJOR ORGANS
Control of the Heart
 Myogenic-Initiated from inside the heart as
opposed to nervous stimulus outside
 Initial Stimulus originates in the Sinoatrial
node (SA node) *show location
 Pacemaker determines heart rate
 Wave of excitation across both atria causes
them to contract
Control of the Heart
 Sinoventricular node (SV node)
 Sends waves of excitation along Purkinje Fibres
which collectively make up the Bundle of Hiss.
Along septum, radiate upwards
 Ventricles contract
 Both atria and both ventricles contract at the same
time
 Systole-contraction of heart
 Diastole-Relaxation/filling of the heart
Diagram
 On Board
Vessels of the Cardiovascular
System
 Arteries – Arterioles – Capillaries - Venules Veins
 Different structures and functions
Arteries
 Carry blood Away from the heart, generally
oxygenated there are some exceptions.
 Blood in arteries in under high pressure
 Their structure is related to their function
 Round in structure with relatively thick walls
composed of three layers
Arteries
A. Tunica Intima – Single layer of endothelial
cells
B. Tunica Media – A thick layer containing
elastic fibres and muscle tissues. Closer to
heart more elastic fibres those further away
have more muscle fibre
C. Tunica Externa – Contains collagen fibres
for strength
Diagram of an Artery
Veins
 Carry blood back to the heart (generally
deoxygenated)
 Blood now flowing slowly, smoothly and under low
pressure (structure related to this function)
 Walls are relatively thin compared with arteries
 Still same three layers but the tunica media differs
in size – relatively narrow with few muscle fibres
and elastic fibres
 Semi Lunar valves present along length
Diagram of Veins
Capillaries
 Link the arterial and venous blood supplies
 Blood flow is slow, blood pressure is falling and is
non-pulsatile
 Capillaries form vast networks in all tissues and
organs
 Composed of only the Tunica Intima, only a single
layer of endothelial cells, no elastic fibres and no
muscle tissue
Capillaries
 Exchange of materials between the blood and
the body takes place in the capillary bed
 Diagram of a capillary bed.
Diagram of a Capillary