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THE CARDIOVASCULAR SYSTEM:
HEART FACTS:
(^) The heart beat approximately 72 beats per minute in the human adult but can increase to rates of 200 beats per minute during exercise. (^) The heart pumps approximately 5.6 liters of blood around your body 3 times a minute at a rate of 70 mL per contraction. (^) The heart has pumped about 1 million barrels of blood by age 76 ( super tankers) or about 1500 gallons/day. (^) Enough energy is generated by the heart in one day to drive a car 20 miles. (^) The heart beats on the average of:
- (^) 72 times per minute
- 4320 times per hour
- 103,680 per day
- 725,760 per week
- 37,739,520 per year
- 2,868,203,520 at age 76
HEART ANATOMY:
(^) Approximately the size of your fist. (^) It is the strongest muscle of your body. (^) Location:
- (^) Superior surface of diagram
- Slightly left of the midline
- Anterior to the vertebral column, posterior to the sternum
ANATOMY: COVERINGS OF THE HEART
(^) PERICARDIUM: a double-walled sac around the heart composed of:
- A superficial fibrous pericardium
- A deep two-layer serous pericardium (^) The parietal layer lines the internal surface of the fibrous pericardium (^) The visceral layer or epicardium lines the surface of the heart (^) They are separated by the fluid-filled pericardial cavity
- Protects the anchors the heart
- Prevents overfilling of the heart with blood
- Allows for the heart to work in a relatively friction-free environment you need to know this
HEART WALL - THREE LAYERS:
- EPICARDIUM: visceral layer of the serous pericardium
- MYOCARDIUM: cardiac muscle layer forming the bulk of the heart (^) Fibrous skeleton of the heart - crisscrossing, interlacing layer of the connective tissue
EXTERNAL HEART: POSTERIOR VIEW
GROSS ANATOMY OF HEART: FRONTAL – bottom of right atrium there is a hole – coronary sinus – make sure you mark it once notes are printed
- AORTIC SEMILUNAR valve lies between the left ventricle and the aorta
- PULMONARY SEMILUNAR valve lies between the right ventricle and pulmonary trunk HEART VALVES
ATRIOVENTRICULAR VALVE FUNCTION
SEMILUNAR VALVE FUNCTION:
HEART SOUNDS:
- HEART SOUNDS (LUB – DUP) are associated with closing of heart valves 1. *First sound occurs as AV valves close and signifies beginning of systole(contraction) (LUB)
PATHWAY OF BLOOD THROUGH THE HEART AND LUNGS:
- Right Atrium -> tricuspid valve -> right ventricle - Right ventricle -> pulmonary semilunar valve -> pulmonary arteries -> lungs - Lungs -> pulmonary veins -> left atrium - Left atrium -> bicuspid valve -> left ventricle - Left ventricle -> aortic semilunar valve -> aorta - Aorta -> systemic circulation
Pathway of Blood Through Heart and Lungs
EXTERNAL HEART: VESSELS THAT SUPPLY/DRAIN THE HEART
(ANTERIOR VIEW):
- ARTERIES: right and left coronary (in atrioventricular groove), marginal, circumflex, and anterior interventricular arteries - VEINS: small cardiac, anterior cardiac and great cardiac veins
CORONARY CIRCULATION:
- Coronary circulation is the functional blood supply to the heart muscle itself - Anastomosis-Collateral routes ensure blood delivery to heart even if major vessels are occluded
*marginal branch – need to know for lecture
*anterior descending artery
ANASTAMOSIS: junction of vessels
- Connection between blood vessels that allow blood to flow to and away from tissues if a vessel gets blocked Be able to identify the veins
MICROSCOPIC ANATOMY OF HEART MUSCLE:
- Cardiac muscle is striated, short, fat, and branched, and interconnected - The connective tissue endomysium acts as both tendon and insertion - Intercalated discs anchor cardiac cells together and allow free passage of ions - Heart muscle behaves as a functional syncytium
MICROSCOPIC ANATOMY OF HEART intercolated disk – have a strong contraction. Increase strength
CARDIAC MUSCLE CONTRACTION:
- Heart Muscle: - Is stimulated by nerves and is self-excitable (automaticity) - Contracts as a unit
- Cardiac muscle contraction is similar to skeletal muscle contraction
HEART PHYSIOLOGY: INTRINSIC CONDUCTION SYSTEM:
- AUTORHYTHMIC CELLS: Initiate action potentials Have unstable resting potentials called pacemaker potentials Use calcium influx (rather than sodium) for rising phase of the action potential
HEART EXCITATION RELATED TO ECG
EXTRINSIC INNERVATION OF THE HEART:
- Heart is stimulated by the sympathetic cardioacceleratory center - Heart is inhibited by the parasympathetic cardioinhibitory center
Extrinsic Innervation of the Heart
ELECTROCARDIOGRAPHY:
- Electrical activity is recorded by electrocardiogram (ECG) - P Wave corresponds to depolarization of SA node - QRS Complex corresponds to ventricular depolarization - T Wave corresponds to ventricular repolarization
- Ventricular systole-contraction
- Isovolumetric relaxation
PHASES OF THE CARDIAC CYCLE:
- Ventricular Filing – mid-to-late diastole - Heart blood pressure is low as blood enters atria and flows into ventricles - AV valves are open, the atrial systole occurs
- Ventricular Systole: - Atria relax - Rising ventricular pressure results in closing of AV valves - Isovolumetric contraction phase - Ventricular ejection phase opens semilunar valves
- Isovolumetric Relaxation: early diastole
- Ventricles Relax Backflow of blood in aorta and pulmonary trunk closes semilunar valves
CARDIAC OUTPUT (CO) AND RESERVE:
- CO is the amount of blood pumped by each ventricle in one minute - CO is the product of heart rate (Pulse) and stroke volume (SV) - Pulse or heart rate is the number of heart beats per minute - SV is the amount of blood pumped out by a ventricle with each beat - Cardiac reserve is the difference between resting and maximal CO
