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Ch 11: The Heart
Cardiovascular System
The Cardiovascular System
This is a closed
system composed
of:
1
...
Blood Vessels
▪ allow blood to
circulate to all
parts of body
Vascular = Blood vessels
The Cardiovascular System
Functions:
1
...
Remove carbon dioxide and other
waste products
Size
▪
About the size of your fist
Location
▪
Thoracic cavity
▪
Medial to the lungs
▪
Superior to the diaphragm
▪
Posterior to the sternum
▪
Pointed apex directed toward left hip,
base pointed to right shoulder
▪
mediastinum
The Heart: Coverings
There are two coverings around heart:
1
...
Serous Pericardium
▪
Inside covering; deep to the fibrous pericardium
▪
a serous membrane
a) Parietal pericardium - outside layer; lining the inner
surface of the fibrous pericardium
b) Viseral pericardium – physically attached to the
heart; also called epicardium
▪ Serous fluid fills the cavity in between
The Heart: Heart Wall
There are three layers
in the heart wall:
Epicardium
1
...
▪
Middle layer
▪
Mostly cardiac muscle
3
...
2
...
4
...
Superior vena cava
2
...
Pulmonary trunk
4
...
Left pulmonary artery
6
...
Two Left pulmonary
veins
8
...
Pulmonary Circuit
▪
▪
2
...
Oxygen-poor blood flows through the inferior and superior venae cavae into the right atrium
2
...
Right ventricle forcefully pumps blood through a valve to pulmonary trunk (which divides into right
and left pulmonary arteries) to lungs
4
...
Oxygen-rich blood from lungs flows through the 4 pulmonary veins into the left atrium
6
...
Left ventricle forcefully pumps blood through a valve to aorta to all tissues in the body
8
...
Bicuspid valve (left)
2
...
Pulmonary semilunar
valve (right ventricle
and pulmonary
artery)
2
...
4
Operation of AV Valves
▪ Ventricles contract
forcing blood against
AV valve flaps
▪ AV valves close
▪ Chordae tendineae
tighten
▪ prevents valve flaps
from everting into atria
Figure 11
...
4
Operation of Semilunar Valves
▪ Ventricles relax
▪ Pressure falls
▪ Blood flows back from
arteries a little
▪ Push against the flaps
▪ Closes semilunar valve
Figure 11
...
Atria contract simultaneously
2
...
6
The Heart: Conduction System
▪ Heart beats are controlled by an intrinsic…
“conduction system”
▪ Allows heart muscle cells to contract, without nerve impulses
▪ Special tissue found no where else in body
The Heart: Conduction System
Consists of:
1
...
Atrioventricular node
▪ causes atria to contract
3
...
Bundle branches
5
...
5