Unit 1: CV System Part C Flashcards
Why is a hydraulic pump required?
In order to sustain the pressure gradients needed to create the blood flow necessary to transport material (nutrients, gases, wastes, etc.) throughout the body
Even when the heart is removed from the body, it can…
continue to beat on its own, without any need for nervous stimulation
List the 5 features of the heart structure?
a. Four chambers
b. Walls of each chamber are composed of 3 layers
c. Pericardial sac
d. Heart Valves
e. fibrous skeleton
What are the 4 chambers of the heart?
i. Left and right atria
ii. Left and right ventricles
List the 3 layers that compose the walls of each chamber
i. Endocardium
ii. Myocardium
iii. Epicardium (= visceral pericardium)
Endocardium
inner epithelial lining of the heart (continuous with lining of blood vessels)
Myocardium
cardiac muscle cells joined together by intercalated disks that contain gap junctions that allow ions to flow directly between cells (electrical coupling)
Ø 99% of cells are normal contractile cells
Ø1% of cells are non-contractile cells referred to as “autorhythmic cells” that form a network called the conduction system
Epicardium
= visceral pericardium)
Øepithelial lining covering the outer surface of the heart
Pericardial sac
Surrounding and protecting the heart
____ of cells are normal contractile cells
99%
____ of cells are non-contractile cells referred to as “_________” that form a network called the ___________.
1%
autorhythmic cells
conduction system
What is the pericardial sac formed from?
formed from parietal pericardium fused to the fibrous pericardium (thick layer of connective tissue)
What does the pericardial sac prevent?
Prevents overdistension of the heart and anchors it to surrounding structures
Where is the pericardial cavity space?
between pericardial sac and epicardium)
What does the pericardial cavity space contain?
contains serous fluid that reduces the friction resulting from contractions
Heart Valves
passive unidirectional valves (open in response to
changes in pressure) that prevent the backflow of blood from the ventricles to the atria or from the large vessels to the ventricles
What do heart valves open in response to?
(open in response to changes in pressure)
Where are the Atrioventricular valves located?
between atria and ventricles
What are the 2 kinds of Atrioventricular valves and where are they located?
Ø tricuspid valve between right atrium and right ventricle.
Ø Bicuspid valve between left atrium and left ventricle
Describe how pressure causes valves to open and close in the ventricles
High pressure in the ventricles due to ventricular contraction closes them.
When ventricles relax, pressure in the ventricles falls below that in the atria and the valves open
Where are the semilunar valves located?
between ventricles and larger arteries
What are the 2 kinds of semilunar valves and where are they located?
aortic semilunar valve between left ventricle and aorta.
pulmonary semilunar valve between right ventricle and pulmonary trunk
High pressure in the ventricles due to ventricular contraction opens them.
When the ventricles relax, pressure in the ventricles falls below that in the
large vessels, and the higher pressure in the aorta/pulmonary trunk closes
the semilunar valves
Fibrous skeleton
connective tissue rings
Describe the function of the Fibrous skeleton
i. Prevent collapse of valve openings. .
ii. Physically and electrically separate atria from the ventricles, allowing atria to contract as a unit to push blood down into ventricles, and allow ventricles to contract as a unit to push blood upwards into the major
blood vessels (aorta and pulmonary trunk/arteries.
