the heart Flashcards
overview
- The right side receives oxygen-poor blood from the body and tissues and then pumps it to the lungs to pick up oxygen and dispel carbon dioxide
- its left side receives oxygenated blood returning from the lungs and pumps this blood throughout the body to supply oxygen and nutrients to the body tissues
strongest part of the heart
-left ventricle
the heart simplified
- cone shaped
- 4 chambers - two atria and two ventricles
- double pump - the ventricles
systemic circulation
-blood vessels that transport blood to and from all the body tissues
pulmonary circulation
blood vessels that carry blood to and from the lungs
-much less pressure then systemic circulation
base
-top of heart
apex
-tip of heart
location of heart
In mediastinum -> behind sternum and pointing left, lying on the diaphragm
weight of heart
It weighs 250-350 gm (about 1 pound)
pericardium layers
- Three layered:
- Fibrous pericardium
- Serous pericardium of layers (2) & (3)
- Parietal layer of serous pericardium
- Visceral layer of serous pericardium = epicardium: on heart and is part of its wall (Between the layers is pericardial cavity)
- Serous pericardium of layers (2) & (3)
myocardium
-muscle of the heart
epicardium
-visceral layer of serous pericardium
endocardium
-layer lining the chambers
layers from out to in
- epicardium
- myocardium
- endocardium
interatrial septum
-divides the left and right ventricles
atrium
- prime the ventricles
- makes sure ventricles are able to enough contract blood
interventricular septum
-separate left and right ventricles
tricuspid valve
-from right atrium to right ventricle
pulmonary or pulmonic valve
-right ventricle to pulmonary trunk (R and L branch)
semilunar valves
-pulmonic and aortic valves
mitral valve (bicuspid)
-left atrium to left ventricle
aortic valve
-left ventricle to aorta
flow
-Body to right heart to lungs to left heart to body
-Body, then via vena cavas and coronary sinus to RA, to RV, then to
lungs via pulmonary arteries, then to LA via pulmonary veins, to LV, then to body via aorta
-From body via SVC, IVC & coronary sinus to RA; then to RV through tricuspid valve; to lungs through pulmonic valve and via pulmonary arteries; to LA via pulmonary veins; to LV through mitral valve; to body via aortic valve then aorta
relative thickness of muscular walls
- LV thicker than RV because it forces blood out against more resistance;
- systemic circulation is much longer than the pulmonary circulation
- Atria are thin because ventricular filling is done by gravity, requiring little atrial effort
heartbeat
a single sequence of atrial contraction followed by ventricular contraction
systole
contraction
diastole
filling
normal heart rate
60-100
tachycardia
greater than 100
bradycardia
-slower than 60
S1 : Heart sound
-S1 is the closing of AV (Mitral and Tricuspid) valves at the start of ventricular systole
S2 : Heart sound
- S2 is the closing of the semilunar (Aortic and Pulmonic) valves at the end of ventricular systole
- Separation easy to hear on inspiration therefore S2 referred to as A2 and P2
murmurs
- the sound of flow
- Can be normal
- Can be abnormal
places to auscultate the heart
-Routine places are at right and left sternal border and at apex
electrical conduction signal
- specialized cardiac muscle cells that carry impulses throughout the heart musculature, signaling the chambers to contract in the proper sequence
- can create its own signal
- originates in the SA node
- AV node delays enough for the atria to contract before the ventricles
- bundle of his
- right and left bundle branches
- right and left ventricles
- purkinje fibers
SA node
- sinoatrial
- in wall of right atrium
- sets basic rate (60-100)
- is the normal pacemaker
- impulse from SA to atria
- impulse also to AV node via internodal pathway
atria
-contract top down
ventricle
-contract bottom up
AV node
In interatrial septum
-40-60
AV bundle (bundle of his)
- Into interventricular septum
- Divides R and L bundle branches become subendocardial branches (“Purkinje fibers”)
contractions being at the
apex
autonomic innervation
- Sympathetic -> Increases rate and force of contractions
- Parasympathetic (branches of Vagus nerve) -> Slows the heart rate
AV node
40-60