anatomy

Is the central component of the cardiovascular system

Propels blood through the blood vessels

How many gallons of blood does the heart pump per year?

Where is the heart located?

Hollow, cone-shaped organ abou the size of a closed fist

How much of the heart lies to the left of the body's midline?

-dense irregular CT
– protects and anchors the heart, prevents overstretchin

– thin delicate membrane
– contains:
• parietal layer-outer layer
• pericardial cavity with pericardial fluid
• visceral layer (epicardium

Layers of Heart Wall:
• Epicardium– visceral layer of serous pericardium

Layers of Heart Wall:
– cardiac muscle layer is the bulk of the heart

Layers of Heart Wall:
– chamber lining, consists of connective tissue covered with endothelium

Whar are the 4 chambers of the heart?

Right Atrium & Great Vessels:
What are the 3 sources of blood?

What partitions the right atrium?

Right Atrium & Great Vessels:
– Blood flows into right ventricle
– has three cusps composed of dense CT covered by endocardium

Forms most of anterior surface of heart

Right ventricle:
What partitions ventricles?

Right Ventricle:
Blood flows into pulmonary trunk, also known assemilunar valve (three cusps each shaped like half moon)

Forms most of the base of the heart• Receives blood from lungs - 4 pulmonary veins (2 right + 2 left)

Left Atrium:
Blood passes through into left ventricle– has two cusps (looks like Pope’s hat – Mitral valve)

Forms the apex of heart

Left Ventricle:
– blood passes through valve into the ascending aorta
– just above valve are the openings to the coronary arteries

Thickness of __________ varies according to the function of the chamber

Myocardial Thickness and Function:
thin walled, deliver blood to adjacent ventricle

Myocardial Thickness and Function:
Ventricle walls are much ________ and stronger

Myocardial Thickness and Function:
Supplies blood to the lungs (little flow resistance)

Myocardial Thickness and Function:
wall is the thickest to supply systemic circulation

Close preventing backflow of blood into atria
– occurs when ventricles contract, pushing valve cusps closed

Open with ventricular contraction– allow blood to flow into pulmonary trunk and aorta

Valves that close with ventricular relaxation– prevents blood from returning to ventricles, blood fills valve cusps, tightly closing the valves

What type of circuits are there for blood circulation?

– left side of heart pumps blood through body
– left ventricle pumps oxygenated blood into aorta
– aorta branches into many arteries that travel to organs
– arteries branch into many arterioles in tissue
– arterioles branch into thin-walled capillaries forexchange of gases and nutrients
– deoxygenated blood begins its return in venules
– venules merge into veins and return to right atrium

– right side of heart pumps deoxygenated blood to lungs
– right ventricle pumps blood to pulmonary trunk
– pulmonary trunk branches into pulmonary arteries
– pulmonary arteries carry blood to lungs for exchange of gases
– oxygenated blood returns to heart in pulmonary veins

Blood supply to the heart

a very active muscle needs lots of O2

Connections between arteries supplying blood to the same region, provide alternate routes if one arterybecomes occluded

• First branches off aorta
• Left coronary artery
• Right coronary artery

Conduction System of Heart:
– cluster of cells in wall of Rt. Atria
– begins heart activity that spreads to both atria (contract simultaneously)
– contraction of all muscle fibers is assisted by presence of “intercalated discs” (gap junctions)
– excitation spreads to AV nod

Conduction System of Heart:
– Cells in wall (septum) between two atria adjacent to the ventricles
– Fires slower than SA node (allow for emptying of atria

Conduction System of Heart:
Signal travels from AV node along AV bundle (bundle of His) to the ventricle

Conduction System of Heart:
Signal branches into the right and left bundle branches in the interventricular septum

Conduction System of Heart
- conduct signals from bundle branches throughout the ventricular myocardium

– Action potentials of all active cells can be detected and recorded

atrial depolarization

Conduction time from atrial to ventricular excitation

Ventricular depolarization

– ventricular repolarization
– atrial repolarization wave is hidden by QRS wave

Stethoscope
Sounds of heartbeat are from turbulence in blood flow caused by valve closure

– first heart sound (_____) is created with the closing of the atrioventricular valves
– second heart sound (_____) is created with the closing of semilunar valves
– contraction of heart chambers is called systole and relaxation is called diastol

Regulation of Heart Rate:
Nervous control from the cardiovascular center in the ________

Increases heart rate and force of contraction

Impulses decrease heart rate

(pressure receptors, located in the arch of the aorta and carotid arteries) detect change in BP and send info to the cardiovascular center in the brain stem

Affected by hormones
– epinephrine, norepinephrine, thyroid hormones
– ions (Na+, K+, Ca2+)
– age, gender, physical fitness, and temperature

Heart muscle receiving insufficient blood supply
– narrowing of vessels---, artery spasm or clot
– smooth muscle & fatty deposits in walls of arteries
Treatment– drugs, bypass graft, angioplasty, stent

– death of area of heart muscle from lack of O2
– replaced with scar tissue
– results depend on size & location of damage

– use clot dissolving drugs streptokinase or t-PA & heparin
– balloon angioplast

Heart pain from ischemia of cardiac muscle