heart ch 20 m flashcards.txt

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heart wall layers
- epicardium: external layer
- myocardium: cardiac muscle
- endocardium: inner layer
av valves
- from RA to RV: tricuspid valve
- from LA to LV: bicuspid (mitral) valve
Semilunar valves
- exiting the RV: pulmonary valve
- exiting the LV: aortic valve
Right Ventricle

forms ANTERIOR surface of the heart
Left Ventricle
- THICKEST chamber of the heart
- Forms the APEX
- Some blood flows into coronary arteries, rest into the body
thickness of Myocardium

Left ventricle works harder to maintain same blood flow as right
cycle of contraction/relaxing
- When atrium is contracting, ventricle must be RELAXING to obtain the blood (papillary muscles RELAX and Chordae tendinae slack)
- valves open when ventricle pressure exceeds artery pressure. Some backflow is permitted here
SYSTEMIC Circulation
- STARTS with RECEIVING blood from the lungs in LEFT ATRIUM
- Ends with veins leading back to RIGHT atrium
PULMONARY Circulation
- STARTS with blood RECEIVED from RIGHT Atrium
- ENDS with blood taken to LEFT ATRIUM via Pulmonary VEINS
CORONARY ARTERIES

Allow heart muscle to receive Sufficient OXYGEN
Autorhythmic FIBERS
- Specialized cardiac muscle fibers
- 1. Act as pacemaker
- 2. Form conduction system
Conduction pathway
- 1. starts in SA node (RA) & goes thru gap jxns to
- 2. AV node in interatrial septum
- 3. enters AV BUNDLE of His (action potential conducted from atria - ventricles)
- 4. enters thru interventricular septum
- 5. PURKINJE fibers conduct ap to myocardium ---ventricles contract
AV node
- act as pacemaker
- rhythm control
NERVE impulses

modify STRENGTH of each heartbeat, NOT RHYTHYM
Autonomic regulation
- Norepinephrine: in SA & AV node it INCREASES the rate of depolarization
- in contractile fibers it enhances Ca entry to INCREASE contractility
Parasympathetic system

releases Acetylcholine: SLOWS depolarization

Author

rincrocci

70807

Card Set

heart ch 20 m flashcards.txt

Description

heart

Updated

2011-03-05T04:38:29Z

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