Cardiovascular System- The Heart


The Heart
  
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Cardiology
 
The study of the heart
The heart beats about
 
100,000 times a day or 35 milion beats a year
Porpels blood through appr.
 
120,00 km of vessels
Two- thirds of the heart lies to the
 
left of the midline
Where does the heart lie
 
Mediatinum
Shape and size of heart
 
Holoow, cone-shaped, about the size of a closed fist
Apex
 
the pointed end on the diaphragm that is directed anterior, inferior, and to the left
Base
 
broader, superior, and directed posterior and to the right
Surface Projection
 
Surface projection is the outlined shape of an organ on the surface of the body Anterior surface Inferior surface Right border Left (pulmonary) border
Intervernticular Septum
 
Seperates the two ventricles
Pericadium- Two layers
 
membrane (sac) that surrounds and protects the heart, it has two layersFibrous pericadriumSerous Pericadium
Fibrous Pericardium
 
superficial layer, tough, inelastic, prevents overstretching, provides protection, and anchors the heart in place
Serous
 
deeper layer, thin; (i) parietal layer - fused to the fibrous pericardium (ii) visceral layer (or epicardium) adheres to the heart itself
Epicardium
 
external layer, composed of mesothelium and connective tissue
Pericardial Cavity
 
between the two layers) is filled with pericardial fluid which reduces friction
Myocardium
 
middle layer, muscular pumping layer, 95% of the heart wall
Endocardium
 
inner layer, consists of a layer of endothelium covering connective tissue, continuous with the endothelium of the blood vessels connected to the heart
Endocarditis
 
inflammation of the endocardium
Cardiac Muscle Characteristics
 
Intercalated discs Desmosomes Gap junctions Sarcoplasmic reticulum
4 chambers of the heart
 
Two superior Chambers- right and left artiaTwo inferior chambers right and left ventricles powerful pumping chambers
Pulmonary Pump
 
right atrium and right ventricle, moves deoxygenated blood through the lungs
Systemic pump
 
left atrium and left ventricle, pumps oxygenated blood to all systems of the body
Three major grooves Sulci
 
Coronay SulcusAnterior Interventricular SuclusPosterior Interventricular suclus
Coronay Sulcus
 
- encircles most of heart, demarcates the atria from the ventricles
Anterior Interventricular Suclus
 
marks the external boundary between right and left ventricles
Posterior Interventricular suclus
 
marks the external boundary between ventricles on the posterior surface
Right Atrium- Receives deoxygenated blood from three veins
 
Superior Vena CavaInferoir Vena CavaCoronary SInus
Superior Vena Cava (SVC)
 
- drains blood from parts of the body superior to the heart
Inferior Vena Cava (IVC)
 
brings blood from all parts of the body inferior to the diaphragm
Coronary sinus
 
receives blood from most of the vessels draining the wall of the heart
Pectinate Muscles
 
Anteroir wall that has interal muscular ridges
Interatrial septum (wall)
 
Seperates the atria
Fossa Ovals
 
oval depression on the septum, remnant of the foramen ovale, a hole between the chambers during fetal development
Blood flows from the right atrium into the right ventricle through
 
the tricuspid valve (or right atrioventricular valve)
Forms most of the anterior surface of the heart
 
Right Ventricle
Trabeculae
 
Inner surface lined with ridges
Chordae tenineae attach the
 
Tricuspid valve cusps to the papillary muscles
The blood passes through the ____ on its way to the lungs
 
pulmonary valve
The blood continues through the _____ which divides into the right and left ___ supplying blood to the right and left lungs for purposes of gas exchange only
 
pulmonary trunk, pulmonary arteries
Left Atrium
 
Forms most of the base of the heart Pulmonary veins carry oxygenated blood (two from each lung)
Bicuspid valve also called
 
mitral valve or the left atrioventricular valve
Left Ventricle
 
Thickest part of the heart Contains trabeculae carneae as well as papillary muscles and chordae tendineae that control inversion of the cusps of the mitral valve Blood passes from the left ventricle into the aorta(largest vessel in the body) by way of the aortic valve
The __ and ______ arteries branch from the _____ to supply the walls of the heart
 
Right, left coronary artieries, ascenfing aorta
The rest of the blood passes into the arch of the aorta and ____ (consisting of ___ aorta and ____ aorta)
 
Descending aorta, thoracic aorta and abdimonal aorta
The ____ , during fetal life, shunted blood from the pulmonary trunk into the aorta leaving the remnant _____ arteriosum
 
ductus arteriosus, ligamentum
Myocardial Thickness and Function The atria
 
thin-walled as they deliver blood under less pressure
Myocardial Thickness and Function- The ventricles
 
have thick walls since they pump blood at a higher pressure and over greater distances The right and left ventricles eject equal amounts of blood
Myocardial Thickness and Function
 
The left ventricle is thicker because it pumps under higher pressure and over a greater distance than the right ventricle
Fibrous Skeleton of the Heart
 
Dense connective tissue (NOT BONE) embedded in the walls of the heart Consists primarily of four fibrous rings that surround the heart valves Prevents overstretching of the valves as blood passes through them
Prevents overstretching of the valves as blood passes through them
 
1. right atrioventricular fibrous ring 2. left atrioventricular fibrous ring 3. pulmonary fibrous ring 4. aortic fibrous ring
The four heart valves prevent
 
blackflow of blood in the heart ater blood passes through them
Atrioventricular (AV) valves
 
tricuspid valve between the right atrium and the right ventricle bicuspid (mitral) valve - between the left atrium and the left ventricle
Two Semilunar (SL) vavles each having three cusps
 
Allow ejection of blood from the ventricles into aorta and pulmonary trunk Prevent backflow of blood into the heart
Pulmonary valve between
 
right ventricle and pulmonary trunk
Aortic valve between
 
left ventricle and aorta
The hear pumps blood into two circuits arranged in series
 
Systematic circulationPulmonary Circulation
Systematic circulation
 
left side of heart receives oxygenated blood from the lungs Pumps this blood into the aorta which branches into systemic arteries that carry blood to all organs except alveoli of the lungsSystemic veins return deoxygeneated blood to the right atrium
Pulmonary Circulation
 
the right ventricle pumps blood into the pulmonary trunk which branches into the pulmonary arteries This blood goes to the pulmonary capillaries where the blood becomes oxygenated Pulmonary veins carry the oxygenated blood to the left atrium
Two Coronary artieries
 
Left and Right coronary artery
Left coronary artery
 
Anterior interventricular Circumflex branch
Right coronary artery
 
Posterior interventricular Marginal branch
Three coronary veins
 
Great cardica veinAnterior cardiac veinMiddle cardiac vein
Great cardiac vein
 
follows the course of the anterior interventricular artery and then the circumflex artery around to the posterior of the hear where it empties into the coronary sinus
Anterior Cardiac vein
 
joins with the small cardiac vein to empty into the coronary sinus
Middle Cardiac Vein
 
empties into the coronary sinus
Coronary circulation
 
Anastomoses are connections between parallel arteries or veins Coronary sinus is a large thin walled vain on the posterior side of the heart that collects all coronary circulation blood
Cardiac Conduction System
 
Autorhythmic cells Pacemaker Conduction system
AS nodes fires
 
spontaneoulsy 90-100 times per minute
AV node firs
 
at 4-50 times per minute
If both AV and SA nodes are suppressed fibers in verntricles by themselves fire
 
only 20-40 times per minute
Artificial pacemakers needed
 
if pace is too slow
Ectopic pacemakers
 
Extra beats forming at other sites caffine and nicotine increases activity
Electrocardiogram-ECG or EKG
 
Action potentials of all active cells can be detected and recorded
P Wave
 
Atria depolarization
P to Q interval
 
Conduction time from atrial to ventricular excitation
QRS complex
 
Ventricular depolarization
T wave
 
Ventriucular repolarization
Cardiac Cycle (Heartbeat
 
Consists of all the events associated with one heartbeat Normally the atria contract while the ventricles relax and vice versa
Systole
 
the contraction phase of a heart chamber
Diastole
 
the relaxation phase of a heart chamber
Cardiac Cycle-major phases
 
At 75 beats/min, one cycle requires 0.8 sec. systole (contraction) and diastole (relaxation) of both atria, plus the systole and diastole of both ventricles
End diastolic volume (EDV
 
volume in ventricle at end of diastole, about 130ml
End systolic volume (ESV)
 
volume in ventricle at end of systole, about 60ml
Stroke volume (SV)
 
the volume ejected per beat from each ventricle, about 70ml SV = EDV - ESV
Blood pressure in aorta is
 
122 mm Hg
Blood pressue in pulmonary trunk is
 
30 mm Hg
Ventricular Pressures
 
Differences in ventricle wall thickness allows heart to push the same amount of blood with more force from the left ventricle The volume of blood ejected from each ventricle is 70ml (stroke volume)
Cardiac Output
 
Amount of blood pushed into aorta or pulmonary trunk by ventricle Determined by stroke volume and heart rate
CO = SV x HR
 
at 70ml stroke volume & 75 beat/min----5 and 1/4 liters/min entire blood supply passes through circulatory system every minute
Cardiac reserve is maximum output/output at rest
 
average is 4-5 while athlete is 7-8
Heart sounds
 
auscultation
Lubb S1
 
due to blood turbulence caused by closing of the AV valves
Second sound dupp S2
 
due to blood turbulence cause by closing of the semilunar valves
The sounds are best heard over
 
the chest at areas slightly away from the actual location of the valves
Risk factors for heart disease
 
Risk factors in heart disease: high blood cholesterol level high blood pressure cigarette smoking obesity & lack of regular exercise. Other factors include: diabetes mellitus genetic predisposition male gender high blood levels of fibrinogen left ventricular hypertrophy
Plasma Lipids and Heart Disease
 
Risk factor for developing heart disease is high blood cholesterol level. promotes growth of fatty plaques Most lipids are transported as lipoproteins
Most lipids are transported as lipoproteins
 
low-density lipoproteins (LDLs) high-density lipoproteins (HDLs) very low-density lipoproteins (VLDLs)
HDLs
 
remove excess cholesterol from circulation
LDLs
 
are associated with the formation of fatty plaques
VLDLs
 
contribute to increased fatty plaque formation
There are two sources of cholesterol in the body:
 
in foods we ingest formed by liver (genetic predisposition)
Desirable Levels of Blood Cholesterol for Adults
 
TC (total cholesterol) under 200 mg/dl LDL under 130 mg/dl HDL over 40 mg/dl Normally, triglycerides are in the range of 10-90 mg/dl. Among the therapies used to reduce blood cholesterol level are exercise
Coronary Artery disease
 
Heart muscle receiving insufficient blood supply narrowing of vessels---atherosclerosis, artery spasm or clot atherosclerosis--smooth muscle & fatty deposits in walls of arteries Treatment drugs, bypass graft, angioplasty, stent

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