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Where is the heart located?
Superior surface of the diaphragm
What is the pericardium?
a double walled sac around the heart
What is the pericardium composed of?
- Superficaial fibrous pericardium
- Serous pericardium
- -parietal layer: lines the internal surface of fibrous pericardium
- -viseral layer/ epicardium: lines the surface of the heart
- Pericardial cavity: contains a film of serous fluid that seperates the parietal and visceral layers
What are the layers of the heart wall?
visceral layer of the serous pericardium (top/ outer layer)
cardiac muscle layer forming the bulk of the heart ( middle layer)
What is the fibrous skeleton of the heart?
criscrossing, interlacing layer of connected tissue
endothelial layer of the inner myocardial suface (inner layer)
What is coronary circulation?
the functional blood supply to the heart muscle itself
_______ ensure blood delivery to the heart even if major vessels are occluded.
What are the valves in the heart in order of the way they are passed?
- Rt. atrium > tricuspid valve > rt ventricle
- Rt. ventricle > pulmonary valve > pulmonary artery
- Lungs> pulmonary veins
- Lt. atrium > mitral/ bicuspid valve > lt. ventricle
- Lt. ventricle > aortic valve > aorta
What is the solid muscle wall in the heart that separates the left and right halves?
How does the blood flow into the heart?
blood enters the heart from the superior and inferior vena cava into the right atrium then passes through the tricuspid valve into the right ventricle. Then it flows into the pulmonary artery passes through the pulmonary valve and then to the lungs. Blood is then pumped into the left atrium through the pulmonary veins. From there the blood passes through the bicuspid/ mitral valve into the left ventricle. it then goes into the aorta and passes the aortic valve and goes to the rest of the body.
What are the areas in which the heart can be heard?
- Aortic valve: 2nd intercostal space at rt. sternal margin
- Pulmonary valve: 2nd intercostal space to the lt. of the sternal margin
- Tricuspid valve: rt. sternal margin of the 5th intercostal space
- Mitral valve: over heart apex (in 5th intercostal space) in line with middle of clavical
Describe cardiac muscle:
striated, short, fat, branched, and interconnected
What does the Sinoatrial (SA) node do?
generates impulses at about 75 times /min
What does the atrioventricular (AV) node do?
recieves the impulses from the SA node at a delayed .1 sec. then it sends the impulses from the artia to the ventricle via the atrioventricular bundle (bundle of His), which splits into 2 pathways in the interventricular septum. The bundle branches carry the impulses towards the apex of the heart and the purkinje fibers carry the impulses to the heart apex and ventricle walls
The heart is stimulated by the ______ cardio-acceleratory center
The heart is inhibited by the __________ cardio-inhibitory center
What are the lub-dub sounds of the heart associated with?
the closing of the heart valves
when does the first sound of the heart occur and what does it signify?
it occurs as the AV valves close and it signifies the begining of ventricular systole
when does the second sound of the heart occur and what does it signify?
it occurs when the Semilunar (SL) valves close and it signifies the begining of ventricular diastole
contractions pf the heart muscle
relaxation of the heart muscle
What are the points of depoloarization and repolarization in heart excitation related to an electrocardiogram (ECG)?
- P: atrial depolarization (SA node depolarization)
- Q, R, S: ventricular depolarization (atrial repolarization-not shown)
- T: ventricular repolarization
What are the phases of the cardiac cycle?
- ventricular filling
- ventricular diastole
- Isometrics relaxation
What is the formua for cardiac output?
CO (ml/min) = HR (heart rate in beats/min) x SV (sroke volume in ml/beat)
what is cardiac output
the amount of blood pumped by each ventricle in 1 min
what is stroke volume?
SV= end diastolic volume (EDV)- end systolic volume (ESV)
what is the end diastolic volume (EDV)?
the amount of blood collected in a ventricle during diastole
what is the end systolic volume (ESV)?
the amount od blood remaining in a ventricle after contraction
what factors affect SV?
- preload: the amount ventricles are stretched by contained blood
- contractablility: cardiac cell contractile force due to factors other than EDV
- afterload: back pressure exerted by blood in the large arteries leaving the heart
What is the Frank -Starling law of the heart?
- preload, or degree of stretch, of cardiac muscle cells before they contract is the critical factor controlling SV.
- slow heartbeat and exercise increase venous return to the heart, increases SV
- blood loss and extremely rapid heartbeat, decrease SV
What extrensic factors influence stroke volume (SV)?
Contractility is the increase in contractile strength, independent of stretch and end diastolic volume (EDV)
Increase in contractility comes from:
- increase in sympathetic stimuli
- certain hormones
- Ca2+ and some drugs
Decrease in contractility comes from:
- increase extracellular K+
- Calcium channel blockers
How do chornotropic factors affect heart rate?
- Positive Chornotropic factors increase heart rate
- Negative Chornotropic factors decrease heart rate
How is the heart regulated by the autonomic nervous system (ANS)?
- Sympathetic nervous system (SNS) stimulation is activated by stress, anxiety, excitement or exercise- increase heart rate
- Parasympathetic Nervous System (PNS) stimulation is mediated by acetylcholine and opposes the SNS- decreases heart rate
- PNS dominated autonomic stimulation, slowing heart rate and causing vagal tone
What is the atrial (Bainbridge) reflex?
- a sympathetic reflex initiated by increase blood in the atria
- causes stimulation of the sinoatrial (SA) node
- stimulated baroreceptors in the atria, causing increase SNS stimulation
How can the heart be chemically regulated?
- hormones, epinephrine and thyroxine, increase HR
- intra- and extra- cellular ion concentrations must be maintained for normal heart functions
What is Congestive heart failure (CHF) caused by?
- coronary atherosclerosis
- persistant high blood pressure
- mutiple myocardial infarcts
- dilated cardiomyopathy (DCM)
What does CHF do to when it happens on the right and left sides?
- Right side- causes a backup of blood (sausage fingers)
- Left side- blood gets in lungs (hard time breathing)
The aspects of a fetal heart:
- right ventricle slightly thicker
- bypass pulmonary circulation
- foramen ovale connect the 2 atria
- ductus arteriosus connects pulmonary truck and the aorta
- foramen ovale closed once 1st solid breath is taken
How does getting to old age affect the heart?
- sclerosis and thickening of valve flaps
- decline in cardiac reserve
- fibrosis of cardiac muscle
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