cardiovascular system the heart. both sides (now)
TRANSCRIPT
Cardiovascular System
The HeartThe Heart
Both Sides (now)
Functions of the Heart
Generating blood pressureRouting blood
–Heart separates pulmonary and systemic circulationsEnsuring one-way blood flow
–Heart valves ensure one-way flowRegulating blood supplyChanges in contraction rate and force match blood delivery to changing metabolic needs
Size, Shape, Location of the Heart
Size of a closed fist
Shape–Apex: Blunt rounded point of cone–Base: Flat part at opposite of end of cone
Located in thoracic cavity in mediastinum
Pericardium
Heart WallThree layers of tissue–Epicardium: This serous membrane of smooth outer surface of heart–Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contracting–Endocardium: Smooth inner surface of heart chambers
Heart Wall
External Anatomy
• Four chambers– 2 atria
– 2 ventricles
• Major veins– Superior vena
cava
– Pulmonary veins
• Major arteries– Aorta
– Pulmonary trunk
External Anatomy
Coronary Circulation
Heart ValvesAtrioventricular
– Tricuspid
– Bicuspid or mitral
Semilunar– Aortic
– Pulmonary
Prevent blood from flowing back
Heart Valves
Function of the Heart Valves
Blood Flow Through Heart
Systemic and PulmonaryCirculation
Heart Skeleton
Consists of plate of fibrous connective tissue between atria and ventricles
Fibrous rings around valves to support
Serves as electrical insulation between atria and ventricles
Provides site for muscle attachment
Conducting System of Hearthttp://www.youtube.com/watch?v=te_S
Y3MeWys&feature=related
Electrical PropertiesAction potentials are:
Sodium ions enter the cell and begin the depolarization
Calcium ions follow and extend the depolarization even further.
Once Calcium stops moving inward, Potassium ions move out and repolarization begins
Specific to the Heart...
•Action Potential is:–Rapid depolarization of heart muscle–Rapid, partial early repolarization of heart muscle –Via Voltage-gated channels–CONFUSED?
Refractory PeriodThe important part of
this cycle is the period where the cells reset and prepare for the next wave. This is called the refractory period because the cells are refractory to (or unaffected by) further stimulation
Refractory Period
• The time between • Absolute: Cardiac muscle cell completely insensitive to further stimulation• Relative: Cell exhibits reduced sensitivity to additional stimulationLong refractory period prevents tetanic contractions
Imagine, if you will, a toilet.
When you pull the handle, (initiate an impulse) water floods the bowl(kinda' like contraction!). This event takes a couple of seconds and you cannot stop it in the middle. Once the bowl empties, the flush is complete. Now the upper tank is empty. If you try pulling the handle at this point, nothing happens (absolute refractory?) Wait for the upper tank to begin refilling (Potassium moves back). You can now flush again, but the intensity of the flushes increases as the upper tank refills (relative refractory...)
ECGAction potentials through myocardium during cardiac cycle produces electric currents than can be measured
Pattern
– P wave
Atria depolarization-firing
– QRS complex
Ventricle depolarization
Atria repolarization
T wave:
Ventricle repolarization-reloading
PQRSTthe P-Wave, representing the impulse across the atria to the A/V Node;The QRS representing the impulse as it travels across the ventricles;the T-Wave, representing the repolarization of the ventricles
Cardiac Arrhythmias
• Tachycardia: Heart rate in excess of 100bpm• Bradycardia: Heart rate less than 60 bpm• Atrial Fibrillation:
describes a condition in which the atrial tissue randomly generates action potentials from many different regions
Alterations in Electrocardiogra
m
Cardiac Cycle
Heart is two pumps that work together, right and left halfRepetitive contraction (systole) and relaxation (diastole) of heart chambersBlood moves through circulatory system from areas of higher to lower pressure.
–Contraction of heart produces the pressure
Cardiac Cycle
Heart Sounds• First heart sound or “lub” (S1-closing
of the tricuspid and mitral valves)– Atrioventricular valves and surrounding fluid vibrations
as valves close at beginning of ventricular systole
• Second heart sound or “dub” (S2- closing of the pulmonic and aortic valves as blood leaves right and left ventricles)– Results from closure of aortic and pulmonary semilunar
valves at beginning of ventricular diastole, lasts longer
• Third heart sound (occasional)
– Caused by turbulent blood flow into ventricles and detected near end of first one-third of diastole
Location of Heart Valves
Heart Homeostasis• Effect of blood pressure– Baroreceptors monitor blood pressure
• Effect of pH, carbon dioxide, oxygen
– Chemoreceptors monitor • Effect of extracellular ion concentration– Increase or decrease in extracellular K+
decreases heart rate
• Effect of body temperature– Heart rate increases when body
temperature increases, heart rate decreases when body temperature decreases
Effects of Aging on the Heart
Gradual changes in heart function, minor under resting condition, more significant during exerciseHypertrophy of left ventricleMaximum heart rate decreasesIncreased tendency for valves to function abnormally and arrhythmias to occurIncreased oxygen consumption required to pump same amount of blood
Pathology (1)
Cardiomyopathy- disease of the heart musclePhlebitis - inflammation of a veinAneurysm - local widening of an arteryCyanosis- bluish color of skinIschemia- diminished blood flowAngina - chest pain
Pathology (2)Petichiae- small, pinpoint hemorrhagesCoronary Artery Disease-blocked arteries leads to ischemiaCongestive heart failure- inability of heart to pump adequatelyClaudication- pain and weakness in a limb as result of decreased blood flow
END
Let’s Do Respiratory!