1. The Cardiovascular system: Heart19
Chapter 11
Pages

2. Chapter 11 Wordbytes Angio-, vascul- = vessel Auri- = ear
Brady- = slow
Cardio-, coron- = heart
-emia = in the blood
Endo- = within
Epi = on top of
Hemangi-= blood vessel
Ische- = to obstruct
Myo- = muscle
Papill- = nipple
Phleb- = vein
Peri = around
Pulmon- = lung
Sphygm- = pulse
Tend- = tendon
Thromb- = blood clot
Ventr- =underside

3. Size, Location, Orientation
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:
Fibrous pericardium-
Inelastic; protects and anchors heart in place
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.

4. Homeostatic Imbalance p.683
Pericarditis  inflammation of pericardium
Creates a creaking sound heard by a stethoscope
Can compress fluid and limit heart’s ability to pump blood

5. p. 682
Figure 15.1

6. 3 Heart Wall Layers: p. 684 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

7. Figure 15.2a

8. Figure 15.2b

9. Figure 15.2c

10. 4 Chambers of Heart
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)

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

12. 4 pulmonary veins enter the left atrium
Transport blood from the lungs back to the heart

13. 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

14. Great Vessels Of Heart- Right p. 687
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

15. Great Vessels –Left p. 687-8 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

16. p
Figure 15.3a

17. p
Figure 15.3b

18. p
Figure 15.3c

19. Blood Supply Of Heart
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

20. Figure 15.5a

21. p. 688
Figure 15.5b

22. Valves p.690
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

23. p. 691
Figure 15.4ab

24. p. 691
Figure 15.4c

25. p. 691
Figure 15.4d

26. Properties of Cardiac Muscle
Striated
Contracts by sliding
Short, fat, branched, interconnected
Contains 1 or 2 centrally located nuclei
Large mitochondria = high resistance to fatigue

27. Conduction System
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

28. Pacemaker 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

29. Figure 15.6

30. Electrocardiogram
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

31. Figure 15.7

32. Cardiac Cycle 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

33. Action Potential Review muscle Heart has addition of External Ca2+
creates a plateau
prolonged depolarized period.
Can not go into tetanus.

34. Figure 15.8

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

36. Controls- Stroke Volume (S.V.)
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

37. Controls- Heart Rate 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- O2, CO2, pH

38. Other Controls Epinephrine & norepinephrine increase H.R.
Hormones:
Epinephrine & norepinephrine increase H.R.
Thyroid hormones stimulate H.R.
Called tachycardia
Ions
Increased Na+ or K+ decrease H.R. & contraction force
Increased Ca2+ increases H.R. & contraction force

39. Figure 15.9

40. Exercise
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

41. Figure 15.10