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The Heart

The Heart. Mary Beth Vogel, BSN, RN-C. Useless Facts!. The human heart creates enough pressure to squirt blood 30 feet There are 60,000 miles of blood vessels in the human body – enough to circle the earth twice! The aorta is almost the diameter of a garden hose

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The Heart

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  1. The Heart Mary Beth Vogel, BSN, RN-C

  2. Useless Facts! • The human heart creates enough pressure to squirt blood 30 feet • There are 60,000 miles of blood vessels in the human body – enough to circle the earth twice! • The aorta is almost the diameter of a garden hose • 20% more people die from heart attacks on Mondays than any other day of the week

  3. Location, Size, Position • Located in thoracic cavity btwn lungs in mediastinum • Two thirds to the left of midline and one third to the right • Apex is just above the diaphragm; base is at the top • Size and shape of a closed fist • Apical pulse: btwn ribs 5 & 6, midpt of L clavicle (5th intercostal space, midclavicular line)

  4. Heart Facts • Begins beating at 4 weeks gestation • Beats over 100,000 times/day • 72 bpm = 103,680 b/24h and 2,000 gallons of blood daily • In a 70-year lifetime, an average human heart beats more than 2.5 billion times, pumping approximately 1 million barrels of blood. • Myocardium: cardiac muscle

  5. Heart Anatomy

  6. 1. Membranes • Heart is enclosed in pericardial membranes • Fibrous Pericardium: sac surrounding the heart; outermost layer • Parietal pericardium: outer layer; lines fibrous pericardium • Visceral pericardium/epicardium: inner layer ; surface of myocardium • Serous fluid btwn layers prevents friction • Why is serous fluid btwn layers important?

  7. Endocardium: simple squamous epithelial tiss that lines the inside of the hearts chambers • This smooth tiss prevents clot formation • Endocardium also lines valves and major vessels that are assoc w/ heart

  8. Cardiac Membrane Disorders • Pericarditis—inflammation of the pericardium • Pericardial effusion: accumulation of fluid btwn parietal and visc layers • Cardiac tamponode—compression of the heart caused by fluid building up between the visceral and parietal pericardium • Endocarditis: inflammation of endocardium

  9. 2. Chambers • 4 total • Lined w/ endocardium • Two upper chambers are called atria (receiving chambers)—right and left atrium • Two lower chambers are called ventricles (discharging chambers) – right and left ventricle • Heart is a double sided pump; intercalated discs allow it to pump as a unit • Wall of each chamber composed of myocardium

  10. 3. Septum • Septum: wall that seperates chambers • Interatrial: btwn 2 atria • Interventricular: btwn 2 ventricles • Septal defects: structural defects of septum; often congenital • VSD, ASD

  11. 4. Valves • Four valves keep blood flowing through the heart; prevent backflow • Two atrioventricular (AV) and two semilunar (SL) valves • 2 AV: separate the atria and ventricles: a. Tricuspid: at the opening from the R atrium into the R ventricle b. Bicuspid (mitral): at the opening of the L atrium into the L ventricle • 2 SL: Btwn vent and the major vessels they empty into a. Pulmonary semilunar: at the beginning of the pulmonary artery b. Aortic semilunar: at the beginning of the aorta http://www.getbodysmart.com/ap/circulatorysystem/heart/anatomy/valves/tutorial.html

  12. cardiac Valve Disorders • Incompetent valves: “leak,” allowing some blood back into the chamber from which it came • Stenosed: narrowed thus decreasing bld flow; cause for murmurs (abnormal, extra sound) • RHD: strept inf that damages myocardium and/or valves. C/b rheumatic fever 1-5 wks post strept • MVP: incompetence of mitral valve; edges extend into the left atrium when the left vent contracts

  13. Mitral Valve Stenosis

  14. Heart Sounds • Noise prod during cardiac cycle • Two distinct sounds in every heartbeat: “lub-dub” • Sound is created by closing of valves • First (lub) sound is caused by closure of AV valves during contraction of vent (vent systole); longer/louder (aka S1) • Second (dub) sound is caused by closure of the semilunar valves during relaxation of vent (vent diastole) (S2) • Pulse deficit: apical – radial (seen in cv disease)

  15. Heart Action • Systole: contraction • Diastole: relaxation • Atrial systole is followed by ventricular systole • Efficient pumping of chambers = rhythmic pumping action • Valves control direction of bld flow • Asystole

  16. Heart Anatomy Review! • What is the difference btwn epicardium and endocardium? • Name the structures btwn the 2 atria and ventricles • Where is apical pulse heard (precisely)? • Give the names and precise locations of all valves • Define systole • What precisely creates the lub dup sounds?

  17. Blood Flow Through the Heart • Heart acts as two separate pumps: R atrium and vent perform diff functions from L atrium and vent • Both sides pump simultaneously • R side of the heart rec deoxygenated bld from body and pumps it to lungs to pick up O2 and dump CO2 • L side of the heart rec oxygenated bld from the lungs and pumps it to the body • Both atria contract together; then both vent • Bld flow is passive from atria to vent but bld is actively pumped from vents to aorta and pul art; thus ventricles are more critical to survival

  18. Systole/Diastole

  19. Blood Vessel Anatomy/Vocab • Arteries: carry oxygenated bld away from heart; elastic and lined w/ smooth musc; distrib nut and O2 to body’s cells • Arterioles • Veins: carry deoxygen bld back to heart; 1 way valves prevent back flow; less elasticity than art thus more prone to clots • Venules

  20. Capillaries: microscopic vessels connect art/vein and allow for gas/nutrient exchange • Artery and Vein layers: • Tunica externa: outer conn tiss layer • Tunica media: mid layer of sm musc tiss (more in art) • Tunica intima: endothelial inner layer (simple squamous epithelial tiss)

  21. Vessel Disorders: • Aneurysm: abnormal weakening/widening in the wall of an art • AAA • Arteriosclerosis: thickening of art wall d/t fat/Ca deposits (hardening of arteries) • Varicies: varicose veins. Bld pools in superficial veins • Phlebitis: vein inflamm • Thrombophlebitis: phlebitis c/b clot (DVT)

  22. Path of Blood Flow Through the Heart: • http://www.medtropolis.com/VBody.asp • Venous/deoxygenated blood enters R atrium through sup and inf vena cava • Deox bld passes from R atrium through tricuspid to R ventricle • Deox bld passes from R ventricle through pulmonary semilunar valve to pulmonary artery and to lungs

  23. In the lungs, CO2 is dumped/O2 picked up • Oxygenated bld travels from lungs to L atrium via 4 pulmonary veins • Oxy bld passes through bicuspid (mitral) valve to L vent • Oxy bld in L vent is pumped through aortic semilunar valve into aorta and is distributed to the body

  24. Blood Flow Thru Heart

  25. Circulation • Systemic Circulation: circ of bld throughout the body • Aorta: 1st vessel of systemic circ • Sup/inf vena cava: last vess of sys circ • Pulmonary Circulation: bld flow to and from lungs • Pul Art: 1st vess of pul circ • Pul veins: last vess of pul circ • Where is B/P highest and lowest? • Others: coronary, portal, fetal

  26. The Aorta

  27. Blood Pressure • B/P gradient: (aorta=100mmHg; vc=0mmHg) and is impt to maintain circulation • Factors that influence B/P: bld volume (cardiac output is @ 5L/min), hrt rate, bld viscosity, peripheral resistance • CVP: B/P w/in R atrium – inf lg periph veins • HTN: > 140/90 (preHTN = 120-139/80-89); normal = < 120/80 • Risk factors: age, race, genes, obesity, stress, Ca def, smoking, sedentary

  28. Circulatory Shock • Lack of bld flow and delivery of O2 to cells • Cardiogenic: hrt failure • Hypovolemic: loss of bld vol • Neurogenic: widespread vasodilation d/t sympathetic ns disruption • Anaphylactic: allergy causes vasodilation • Septic: toxins cause vasodilation

  29. Coronary Circulation • Coronary arteries: • Bld supply for the myocardium • R&L coronary arteries (R&L main) are 1st branch from aorta • L Main primary branches: circumflex and LAD • These are most likely to be affected by coronary artery disease (CAD) • CAD dx by cardiac cath • http://www.crozer.org/medinfo/a_playr/player/cath/p_cath.htm#cath_h

  30. Coronary arteries

  31. Coronary veins: • Collect the oxygen-poor blood from myocardium • Coronary veins empty blood directly into the right atrium through the coronary sinus • Coronary sinus is a small hole in the right atrium protected by a flap of tissue

  32. Coronary arteries and veins

  33. Coronary sinus

  34. Coronary Artery Disorders • MI: blockage of blood flow through the coronary arteries can cause ischemia (lack of O2 causing tiss impairment): prolonged ischemia = infarct (area of necrosis) • S/S: chest, jaw, shoulder pain, n/v, SOB, diaphoresis • Tx: prevention, CABG • Predisposing factors: genes, HTN, DM, smoking, poor diet, high LDL, obesity, sedentary lifestyle

  35. 2. Angina pectoris: chest pain d/t lack of O2 to myocardium. d/t a narrowing of the coronary art from arteriosclerosis • S/S: usually occurs during exertion, severe emotional stress, or after a heavy meal • Tx: nitroglycerin • 3. Arteriosclerosis: hardening/thickening of walls of arteries • Fatty deposits, calcification of wall of art or thickening of the muscular wall of art from chronic HTN • Tx: variety of meds

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