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The heart is located within…
The mediastinum just above the diaphragm
The heart is enclosed in a…
Pericardium
The heart is a…
Hallow muscle double pump
The heart is divided into…
Four chambers
The left and right chambers of the heart have a…
Collecting chamber (an atrium) and a pumping chamber (a ventricle)
There are three principal circulatory divisions in the cardiovascular system:
Systemic circulation
Pulmonary Circulation
Coronary Circulation
Systemic circulation carries…
Oxygenated blood from the left ventricle through the body, and returns venous blood to the right atrium
Pulmonary circulation carries…
Venous blood from the right ventricle through the lungs (blood undergoes oxygenation) and delivers oxygenated blood through four (4) pulmonary veins into the left atrium
Coronary circulation delivers…
Oxygenated blood for the heart through the coronary arteries
Venous blood from the heart through cardiac veins collects…
Collects into the coronary sinus and empties into the right atrium
Both pumps contract at…
The same time and both sides pump equal amounts of blood with each cycle of contraction and relaxation
Contraction
Systole
Relaxation
Diastole
General Organization of the Circulatory System
Closed system
Heart
Arterial System
Venous System
Microcirculation
Systemic circulation
Pulmonary circulation
Blood movement through the heart goes from the systemic circulation (venous blood) to the…
Superior/ Inferior Vena Cava
From the superior vena cava the blood moves to…
The right atrium
From the right atrium the blood moves to…
Right ventricle
From the right ventricle the blood moves to…
Pulmonary Arteries (L/R)
From the pulmonary arteries the blood moves to…
Pulmonary circulation
From the pulmonary circulation the blood moves to…
The pulmonary veins
From the pulmonary veins the blood moves to…
The left atrium
From the left atrium the blood moves to…
The left ventricle
From the left ventricle the blood moves to…
The aorta
From the aorta the blood moves to…
The systemic circulation (arterial blood)
Heart Wall Morphology
Pericardium
Epicardium
Myocardium
Endocardium
Pericardium
Composed of fibrous pericardium + visceral and parietal layers
Epicardium
Superficial visceral layer of the serous pericardium
Myocardium
Composed of the contractile cells - part which actually contracts
Endocardium
Composed of epithelial and connective tissue + elastic fibers
Skeletal muscles are composed of…
A big number of muscle fibers (cells)
Each muscle fiber has…
The same length as a muscle
Skeletal muscle fibers have a signficant…
Number of nuclei (myonuclei), which are located beneath the sarcolemma
Cardiac muscle cells (myocytes) are arranged in…
Layers and are shorter than skeletal muscles
Cardiac muscles has properties of…
A skeletal muscle and of a smooth muscle
Cardiac muscle cell has only…
1-2 nuclei (myonuclei)
Cardiac muscle cells are connected through…
Intercalated discs
Gap junctions in the intercalated discs are…
Similar to those in the smooth muscles
Cardiac muscle is a…
Syncytium
Gap junctions in intercalated discs provide…
Low electrical resistance
Intercalated discs separate…
Cardiac Cells
The different syncytiums
Artrial Syncytium
Ventricular Syncytium
Myocyte is surrounded by…
The plasma membrane - sarcolemma
Cytoplasm of the cardiac cell contains…
Contractile proteins (Myofilaments)
Myofilaments are composed of…
Actin and Myosin
Actin and myosin have a…
Parallel orientation along the axis of the fiber/myocyte
Thin filament (actin) is anchored to the…
Z-Disc (Z-Line)
Distance between two Z-lines is a…
Functional unit of a cardiac cell -sarcomere
Between myofibrils…
Abundant mitochondria are found
The smooth endoplasmic reticulum is also known a…
Sarcoplasmic Reticulum
The smooth endoplasmic reticulum (sarcoplasmic reticulum) is a…
Storing site of calcium ions in the cell
Electrical Properties of the Cardiac Muscle
Resting membrane potential in cardiac cells (-85 to -95 mV)
Resting membrane potential in conductive fibers (-90 to -100 mV)
Resting potential is stable
The resting membrane potential in cardiac cells…
-85 to -95 mV
The resting membrane potential in conductive fibers…
-90 to -100 mV
Phase 0
DEPOLARIZATION (Na+ enters in about 2 msec)
Phase 1
EARLY REPOLARIZATION (Na+ channels start to incativate)
Phase 2
PLATEAU (Ca2+ enters about 200 msec)
Phase 3
REPOLARIZATION (K+ channels open)
Phase 4
ION DISTRIBUTION RESTORED (Na+/K+ pump)
Action Potential in the Cardiac Muscle
Prolonged action potential and plateau in cardiac muscle
Opening of fast sodium channels (open 1/1000 s) - Phase 0
Opening of slow calcium channels (open 1/10 s) - Phase 2
Maintained a prolonged period of depolarization
Very long (250 ms) refractory period (Impossible to cause stimulation of contractions)
Excitation-Contraction Coupling
Action Potential
Calcium Transients
Resting cytosolic calcium is increased
10% of calcium enters via calcium influx through T-tubules into the sarcoplasmic reticulum
Calcium is released from the sarcoplasmic reticulum
Calcium combines with troponin
Tropomyosin’s inhibition is removed
Criss-bridges are formed
Contraction
Sarcoplasmic reticulum of cardiac cells is…
Less developed than of skeletal muscles
T-Tubules of cardiac cells have…
large diameter (5 times more than of skeletal muscles)
Electronegative mucopolysaccharides bind…
Calcium ions in T-Tubules
T-tubules open directly…
To the outside of the cardiac cells
Extracellular calcium significantly affects…
Cardiac cell contraction
Systole
250-300 ms
Diastole
500-550 ms
Atrial Contraction is initiated by…
Generation of action potential in the sinus node
Atrial Contraction (A-B)
Mitral valve is opened
Aortic valve is closed
75% of blood flows directly from atrias into ventricles
25% of blood flows into ventricles due to atrias contraction
Isovolumic (Isometric) Ventricular Contraction
Mitral valve is closed
Aortic valve is closed
Volume of blood in ventricles remains constant
Ventricles contract. Pressure in the ventricles is building
Ventricular Ejection (Rapid Ejection Period and Slower Ejection Period)
Mitral valve is closed
Aortic valve is opened
Ventricles continue contracting
Isovolumic (Isometric) Ventricular Relaxation
Mitral valve is closed
Aortic valve is closed
Ventricles relaxing
Pressure rapidly drops to diastolic values
Passive Ventricular Filling
Mitral valve is opened
Aortic valve is closed
Blood collects in atrias
Blood fills the ventricles
End Systolic Pressure (ESP)
120 mmHg
End Diastolic Pressure (EDP)
0 mmHg
These volumes are found within the heart…
End Systolic Volume (ESV)
End Diastolic Volume (EDV)
Stroke Volume
65 mL
Sound travels through the…
Chest
When valves close…
Pressure gradient develops
During the cardiac cycle the surrounding tissue, fluids, and blood vessels…
Vibrate
Frequency of heart sounds during the cardiac cycle
3 Hz - 40 Hz - 500 Hz
Normal sounds consists of…
First Heart Sound (S1)
Second Heart Sound (S2)
Third Heart Sound (S3)
Abnormal Sounds
Murmurs of the Heart
The first heart sound (S1) has a…
“LUB” (A-V valves vibration at the beginning of systole) 0.14
The two components of the first heart sound…
Mitral
Tricuspid
The second heart sound (S2) is a…
Higher frequency than the first sound
The second heart sound (S2) has a…
“DUP” (Aortic valves vibration at the end of systole) 0.11s
The two components of the second heart sound (S2)
Aortic
Pulmonic
Third heart sound (S3)
Occasional weak sound, recorded in the phonocardiogram
Dr. Rene Lannec
Discovered the stethoscope (1816)
Cardiac output is…
The amount of blood ejected from the heart
Cardiac Output equals…
Heart Rate x Stroke Volume
Heart Rate is…
68-72 per min
Cardiac Output is determined by…
The autonomic effects upon the SA node
Stroke Volume is…
65-75 mL
The two different controls of the Cardiac Output…
Intrinsic Control (Venous Return)
Extrinsic Control (Sympathetic Stimulation)
Blood Pressure equals…
Heart Rate x Stroke Volume x Resistance
Parasympathetic N.S has…
No effect on stroke volume
The venous return can…
Increase or decrease stroke volume
Autonomic Effects are due to…
Sympathetic and Parasympathetic N.S
