Chapter 13 Pages

1. Angio- = vessel 2. Auri- = ear 3. Cardio-, cor- = heart 4. -emia = in the blood 5. Endo- = within 6. Epi = on top of 7. Ische- = to obstruct 8. Myo = muscle 9. Papill- = nipple 10.Peri = around 11.Pulmon- = lung 12.Tend- = tendon 13.Ventr- =underside

 About the size of a fist; weighs less than a pound  Found in thoracic cavity between two lungs = mediastinum (medial cavity of thorax) ◦ ~2/3 to left of midline  Surrounded by pericardium: 1. Fibrous pericardium- ◦ Inelastic; protects and anchors heart in place 2. Inside is serous pericardium- double layer around heart ◦ Parietal layer fused to fibrous pericardium ◦ Inner visceral layer adheres tightly to heart ◦ Filled with pericardial fluid- reduces friction during beat.

Pericarditis  inflammation of pericardium –Creates a creaking sound heard by a stethoscope –Can compress fluid and limit heart’s ability to pump blood

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1. Epicardium- outer layer (contains fat) 2. Myocardium- cardiac muscle = bulk of heart; what contracts ◦ Two separate networks via gap junctions in intercalated discs- atrial & ventricular ◦ Networks- contract as a unit 3. Endocardium- Squamous epithelium ◦ Lines inside of myocardium

 2 superior chambers= atria (receiving chambers) ◦ Contains auricles  small, wrinkled, protruding appendages ◦ 2 Parts: ◦ 1.smooth-walled posterior ◦ 2.anterior = ridged by bundles of muscles ◦ Between is interatrial septum ◦ Contains fossa ovalis- remnant of foramen ovalis (opening in fetal heart)

 Blood enters right atria via 3 veins: 1.Superior vena cava (from body regions superior to diaphragm) 2.Inferior vena cava (from body areas below diaphragm) 3.Coronary sinus (collects blood from myocardium)

 4 pulmonary veins enter the left atrium ◦ Transport blood from the lungs back to the heart

 2 inferior chambers = ventricles (discharging chambers = pumps) ◦ Make up most of the mass of the heart ◦ Between is interventricular septum ◦ Right ventricle pumps blood into the pulmonary trunk (to lungs for gas exchange) ◦ Left ventricle pumps blood into the aorta = largest artery in the body  Wall thickness depends on work load ◦ Atria thinnest ◦ Right ventricle pumps to lungs & thinner than left

 Superior & inferior Vena Cavae ◦ Delivers deoxygenated blood to R. atrium from body ◦ Coronary sinus drains heart muscle veins  R. Atrium  R. Ventricle  pumps through Pulmonary Trunk   R & L pulmonary arteries   lungs

 Pulmonary Veins from lungs ◦ oxygenated blood   L. atrium  Left ventricle   ascending aorta  body  Between pulmonary trunk & aortic arch is ligamentum arteriosum  fetal ductus arteriosum remnant

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 Blood flow through vessels in myocardium = coronary circulation  L. & R. coronary arteries ◦ branch from aorta ◦ branch to carry blood throughout muscle  Deoxygenated blood collected by Coronary Sinus (posterior)  Empties into R. Atrium

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 Designed to prevent back flow in response to pressure changes  Atrioventricular (AV) valves ◦ Between atria and ventricles ◦ Right = tricuspid valve (3 cusps) ◦ Left = bicuspid or “mitral” valve ◦ Chordae tendineae – “heart strings” = anchor cusps to muscles  Semilunar valves near origin of aorta & pulmonary trunk ◦ Aortic & pulmonary (semilunar) valves respectively

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 Striated  Contracts by sliding  Short, fat, branched, interconnected  Contains 1 or 2 centrally located nuclei  Large mitochondria = high resistance to fatigue

 1% of cardiac muscle generate action potentials= Pacemaker & Conduction system  Normally begins at sinoatrial (SA) node   Atria contracts   AV node -slows   AV bundle (Bundle of His)   bundle branches  Purkinje fibers   apex and up- then ventricles contract

 Depolarize spontaneously  sinoatrial node ~100times /min  also AV node ~40-60 times/min  in ventricle ~20-35 /min  Fastest one run runs the heart = pacemaker  Normally the sinoatrial node

 Recording of currents from cardiac conduction on skin = electrocardiogram (EKG or ECG)  P wave= atrial depolarization ◦ Contraction begins right after peak ◦ Repolarization is masked in QRS  QRS complex= Ventricular depolarization ◦ Contraction of ventricle  T-wave = ventricular repolarization ◦ Just after ventricles relax

 after T-wave  ventricular diastole ◦ Ventricular pressure drops below atrial & AV valves open  ventricular filling occurs  After P-wave  atrial systole ◦ Finishes filling ventricle (`25%)  After QRS  ventricular systole ◦ Pressure pushes AV valves closed ◦ Pushes semilunar valves open and ejection occurs ◦ Ejection until ventricle relaxes enough for arterial pressure to close semilunar valves

 Review muscle  Heart has addition of External Ca 2+  creates a plateau  prolonged depolarized period.  Can not go into tetanus.

 Cardiac Output (CO) = liters/min pumped  Heart Rate (HR) = beats/minute (bpm)  Stroke volume (SV) = volume/beat  CO = HR x SV

 Degree of stretch = Frank-Starling law ◦ Increase diastolic Volume increases strength of contraction  increased S.V. ◦ Increased venous return  increased S.V.  increased sympathetic activity  High back pressure in artery  decreased S.V. ◦ Slows semilunar valve opening

 Pacemaker adjusted by nerves ◦ Cardiovascular center in Medulla  parasympathetic- ACh slows ◦ Via vagus nerve  Sympathetic - norepinephrine speeds  Sensory input for control: ◦ baroreceptors (aortic arch & carotid sinus)- B.P. ◦ Chemoreceptors- O 2, CO 2, pH

 Hormones: ◦ Epinephrine & norepinephrine increase H.R. ◦ Thyroid hormones stimulate H.R. ◦ Called tachycardia  Ions ◦ Increased Na + or K + decrease H.R. & contraction force ◦ Increased Ca 2+ increases H.R. & contraction force

 Aerobic exercise (longer than 20 min) strengthens cardiovascular system  Well trained athlete  doubles maximum C.O.  Resting C.O. about the same but resting H.R. decreased