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What is the function of the heart?
To pump blood throughout the body to all organs
How would we describe the location of the heart?
Mediastinum= extends from the sternum to the vertebrae
Apex of the heart= tip of the left ventricle
Base of the heart= posterior surface
What is the pericardium?
Membrane that surrounds and protects the heart
What are the two main parts of the pericardium?
1. Fibrous pericardium
outer portion=dense irregular connective tissue
a. prevents overstretching of the heart
b. provides protection
c. anchors heart in the mediastinum
2. Serous pericardium=inner portion has two layers
a. viseral pericardium- inner layer aka epicardium
b. parietal pericardium- outer layer
What is the pericardial cavity?
The space that contains the pericardial fluid, which reduces friction between the layers of the serous pericardium as the heart moves
How is the walls of the heart constructed?
A. Epicardium=visceral pericardium
-thin layer of connective tissue
-smooth, slippery texture
B. Myocardium=cardiac muscle 95% ofthe heart wall
C. Endocardium=endothelium
-smooth inner lining that also covers the valves and is continuous with the endothelium that lines the blood vessels 
What are the chambers inside the heart?
A. Atria
1. Function=recieve blood returning to heart
-thinner walls than the ventricles
2. Right atrium
-recieves deoxygenated blood from superior vena cava, inferior vena cava, coronary sinus
3. left atrium
-recieves oxygenated blood from the pulmonary veins
4.auricles=ear like pouches attached to each atrium-added space for blood
What are the ventricles job?
1. function=pump blood away from the heart
-thicker walls than atria
2. right ventricle=pumps blood out the pulmonary trunk to the lungs
3. left ventricle=pumps blood outthe aorta tothe body organs
Why does the left ventricle have a thicker wall than the right ventricle?
Because the left ventricle has to pump blood throught the entire body
What structures separate the right and left side of the heart?
A. interatrial septum
B. Interventriculsr septum
What happens if either septum is incomplete?
There is a decrease flow of blood to the lungs and mixing of both blood (oxygenated and deoxygenated) causes cyanosis
What pathway does blood flow?
coronary sinus, superior vena cava, inferior vena cava->r. atrium->r. ventricle->pulmonary trunk->r. and l. pulmonary arteries->lungs->r. and l. pulmonary veins->l. atrium->l. ventricle-> aorta (systemic circulation)
How do the heart valves control blood flow?
A. Function of the valves
To keep blood from back flow and keep it moving foward
B. Valves are constructed into little cusps that come together during contraction
What are the two groups of valves?
A. atrioventricular valves=between the atria and ventricles (AV valves)
B. semilunar valves=between the ventricles and blood vessels leaving the heart (SL valves)
    Name the two atrioventricular valves?
1. tricuspid valve=right side
2. bicuspid (mitral) valve=left side
How do the AV valves work with ventricle contraction?
The chordae tendineae are slack when the bicupid valve cusps are opened and the papillary muscles are relaxed. When the bicuspid valve is closed  the chordae tendineae tighten and papillary muscle contract and pull on the chordae tendineae
When do the AV valves open?
When the ventricles are relaxed
   Name the semilunar valves
1. pulmonary semilunar valve=between the pulmonary trunk and right ventricle
2. aortic semilunar valve=between the aorta and the left ventricle
How do the semilunar valves work?
When the heart contracts, blood flows through the semilunar valve
When do the semilunar valves open?
When the heart contracts
Why does the heart needs its own blood supply?
A. Coronary circulation
1. coronary arteries- branch of aorta
2. corornary veins- feed into the coronary sinus
B. heart disease
1. plaque
2. blockage
3. Angina
4. Myocardial infarction (MI)
5. bypass
6. angioplasty
7. stent
What are autorhythmic fibers?
-specialized cardiac muscle fibers that are self-excitable
-can generate action potentials with no external stimulus needed
What is the conduction system of the heart?
-network of autorhythmic fibers running through the heart
1. SA node
2. AV node
3. AV bundles (Bundle of his)
4. right and left bundle branches
5. purkinje fibers
What is the sequence of events in the conduction system?
1. sinoartrial node in the wall of the  right atrium depolarizes spontaneously and triggers  an action potential (AP). The AP spreads throughout the bth atria which causes the atria to contract 2. The AP will reach the atrioventricular node
3. The AP will then travel down into the atrioventricular bundle
4. The AP travels down the right snd left bundle branches toward the ventricles
5. Purkinje fibers then carry the AP deep into the myocardium of the ventricles
6. This cause the ventricles to contract 
How does the SA node act as a pacemaker?
Because action potentials spreas through the conduction system and stimulate other areas before the other areas are able tp generate an action potential. Depolarization to threshold spontaeously
How can the AV node be important?
If the SA node isn't working properly AV node kicks as the stand in beating at 60 bmp
What is the job of an artificial pacemaker?
To send out small electrical currents to stimulate the heart to contract
What are heart arrhythmias?
abnormal rthym as a result of a defect in the conduction system
What are some different types of arrhyhmias?
1.heart block- electrical pathway between the atria and ventricle are blocked
A. First degree heart block- AV blocked P-Q interval is prolonged, usually condition through the AV node is prolonged
B. Second degree heart block- Some of the AP from SA node are not conducted through  the AV node "dropped" beats fewer QRS complexes than P waves on ECG
C. Third degree heart block- No SA node action potentials get through the AV node. Autorhymic fibers in the atria and ventricles pace the upper and lower chambers seperately, with complete AV block, ventricular contraction rate is less than 40 beats/min
What is an electrocardiograph?
The machine used to record EKG's
What is Atrial Flutter?
Rapid regular atrial contractions 240-300 beats/min. Acompanied by an AV block in which some of the nerve impulse from SA node are not conducted through AV node
What are the three major deflection waves?
P waves -atrial depoarization
QRS complex- when the ventricles depolarizes
T wave-repolarization of the ventricled
What is a Defibrillator?
A device  that gives electrical shocks, applied via 2 large paddles shape electrodes pressed down against the skin on the chest
What is an electrocardiogram (ECG or EKG)?
A record of the electrical changes occurring as action potential spreads through the heart
What is a cardiac action potential like?
Resting memebrane potential = -90 mV
threshhold level = -75 mV
What are the three major phases in the generation of action potentials in cardiac muscle fibers?
(1)
1. Rapid depolarization ohase
a. voltage-gated fast sodium ion channels open and Na+ rush into the cardiac muscle cell
b. depolarization occurs and the voltage changes to about +30mV
c. Na+ channles close quickly
 
What are the three major phases in the generation of action potentials in cardiac muscle fibers? 
(2)
2. Plateau phase
a. voltage-gated slow Ca++ channels open allow Ca++ to flood into the cardiac muscle cell
b. some voltage-gated K+ channels open about the same time and allow K+ to leave the cardiac muscle
c. this creates a maintained depolarizatoin because Ca++ inflow just balances K+ outflow
What are the three major phases in the generation of action potentials in cardiac muscle fibers?
(3)
3. Repolarization phase
a. slow Ca++ channels close
b. additional voltage K+ channels open
c. more K+ ions leave the cardiac muscle cell
d. membrane potential returns to resting -90 mV
How does action potential travel?
Along the conduction system and spreads out to excite the "working" atrial and ventricles muscle fibers called contractile fibers
How is cardiac muscle contraction similar to skeletal muscle contraction?
AP leads to the mechanical (contraction) after a short delay Ca2+ rises inside a contractile fibers, Ca2+ binds to the regulatory protein tropin which allow the actin and myosin filaments to begin sliding pass one another
How is Aerobic cellular repiration in ATP production in Cardiac musle?
- reaction reqiuring oxygen
-oxygen provided by coronary circulation
-at rest, heart celss use fatty acids and glucose to make ATP
What is Creatine phosphate (CP) with ATP produciton in cardiac muscle?
-used in he same way skeletal muscles do
-creatine kinase (CK)= enzyme released into blood when cardiac cells are injured or dying-occurs during a heart attack
-presence of CK in blood indicates a heart attack has occured 
What are the major phases in the heart function?
A. Systole= contraction phase
B. Diastole= relaxation phase
What is the cardiac cycle? 
all the events associated with one heartbeat
1. atrial systole and diastole
2. ventricular systole and diastole
What is the relationship between volume and pressure?
Inverse relation                            When volume ^ pressure v
When volume v pressure ^
Major events of the cardiac cycle
1-3 Atrial systole
A. Atrial systole=0.1
1. before atrial systole  begins, the ventricles have already filled to abouth 70% of their normal capacity during the diastole of the previouis cycle
2. AV valves open- the atria now contract and this increases the pressure inside the atria-rising pressure inside the atria causes the flaps of the AV valves to be pushed open so the AV valves open
3. now the ventricles finish filling with the remaining 30% of their normal volume as blood flows in from the atria
Each ventricle has 105 milliters of blood
25mL goes into each ventricle (increase in pressure of atriums)
Major events of the cardiac cycle
Ventricular systole (1)
Ventricular Systole=0.3 seconds
(atria are in diastole)
1. Ventricular systoe-First phase
a . Av valves close-
the ventricles begin to contractand as pressure inside the ventricles increases, blood pushes the flaps of the AV valves closed
b. Isovolumetric contractions
-there is a brief period when all four heart valves are closed=isovolumetric contraction
Major events of the cardiac cycle
Ventricular systole (2)
2.Ventricluar systole- second phase
a. semilunar valves open
-pressure inside the ventricles now become greater than the pressure inside the aorta and pulmonary trunk-this causes the SL valves to open
b. Ventricular Ejection
blood now flows out of the ventricles into the aorta and pulmonary trunk
c. END-SYSTOLIC VOLUME= ESV=60ml
ESV= the amount of blood remaining in the ventricles at the end of ventricular systole  
Major events of the cardiac cycle
Ventricular diastole  (1)
Ventricular diastole=0.4 seconds (atria are also in diastole at this time)
1. ventricular diastole-early phase a. semilunar valves
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