1. THE CIRCULATORY SYSTEM
Ch. 18 The HEART

3. ASSIGNMENT: Most Of The Anatomy We Have Already Done In The Lab, So Make Sure To Do The * of slide 1 through 29.
As I Will Likely Not Take The Time To Review This Material.

4. *PARTS OF THE CARDIOVASCULAR SYSTEM
*1. *2. *3.

6. I. Heart Anatomy Midsternal line 2nd rib Sternum Diaphragm
*A. Size, Location, and Orientation
*Size:
*Location:
*Orientation of Apex & Base
STUDY QUESTION EXAMPLES:
1. Describe the Heart’s Size, Location, Orientation, Coverings, and Wall Layers
Midsternal line
2nd rib
base
Sternum
Diaphragm
Point of
maximal
intensity
(PMI)
apex

7. B. Coverings of the Heart
2A Review See text p. 18
*Serous Membranes
- *P_________
- *V_________
- *for Heart named:
*Cavity
- * and that cavity
is in the M____________________
(page 665)

8. 1. *Pericardium: Description = double-walled sac
B. Coverings of Heart …
1. *Pericardium: Description = double-walled sac
Fibrous pericardium – Function: Protection & Anchoring
Parietal pericardium
Visceral Pericardium
= epicardium = is the same as the Visceral Pericardium
*Serous fluid:
Outer
Sac
Inner
Sac
Figure 11.1a–b

9. The Heart = pump of the cardiovascular system
Superior
vena cava
Aorta
Parietal
pleura (cut)
Pulmonary
trunk
Left lung
Pericardium
(cut)
Apex of
heart
Diaphragm
(c)
Figure 18.1c

10. C. *Layers of the Heart Wall
1. *Epicardium
2. *Myocardium
What type of tissue:
3. *Endocardium – endothelium: is what type of tissue
Figure 11.2b

11. D. Fibrous Cardiac Skeleton (page 666)
Connective Tissue
*Thickest in what areas and why?
Electrical Characteristics:
*Can action potentials pass through it?
Importance: limits the spread of action potentials through the cardiac muscle to certain areas, or pathways (… in “III-A. Electrical Events”)
2. What is the Fibrous Skeleton and what is its purpose?
Cardiac
muscle
bundles

12. E. Chambers and Associated Great Vessels Overview
*Atria:
*Auricles
*Ventricles:
*Interatrial & Interventricular Septa: location & description?
*Sulci = describe?
Coronary Sulcus = Atrio- Ventricular Sulcus
*Anterior Interventricular Sulcus: location? What is within it?
*Posterior Interventricular Sulcus: same questions as above?

13. E. Chambers and Associated Great Vessels … 1. *Atria
*Pectinate Muscles
Fossa Ovalis adult, indents in
Foramen Ovale: hole with flap to bypasses RV & lungs in fetus
Right
*Superior Vena Cava: Blood from where to where?
*Inferior Vena Cava: same?
Coronary Sinus: collects blood from Coronary veins
Left
*Pulmonary Veins: from where to where?

14. 2. *Ventricles& Blood & Vessels– 2 pumps
Right vs. Left
*Shapes:
*Thickness, why?
*Trabeculae carneae
*Papillary Muscles
*Right: Pulmonary Trunk blood goes where?
*Left: Aorta– Blood goes where?
*Coronary Arteries: Branch of ?
Blood goes where?
2. *Ventricles& Blood & Vessels– 2 pumps
Figure 11.4

15. F. Pathway of Blood Through the Heart
1. 2 PUMP SYSTEM two circulations
Blood Flow Direction:
Pulmonary Circulation: Blood vessels from R Ventricle  Lungs  Left Atria
Systemic Circulation: Blood vessels from Left Ventricle  Body  Right Atria
Blood Vessels in Pathway:
Sup & Inf Vena Cava & Coronary Sinus  RA  RV  Pulmonary Trunk  Pulmonary Arteries  Lungs  Pulmonary Veins  LA  LV Aorta  Cells & Coronary Arteries
5. Describe the path a blood cell would take starting with the Right Atria and ending back at the RA.

16. G. *Coronary Circulation =?
*Coronary Arteries:
a) *Supply the heart muscle w what?
b) *Branch from:
2. *Branches of the Left Coronary Artery =
3. *Branches of the Right Coronary Artery =
Figure 11.2a

17. Left coronary artery Right coronary artery Right marginal artery
Aorta
Left
coronary
artery
Right
coronary
artery
Right
marginal
artery
Circumflex
artery
Anterior
interventricular
artery
Posterior
interventricular
artery
Figure 18.7a

18. (b) The major cardiac veins
Aorta
G. Coronary Circulation … 5. Cardiac Veins - *Function? Coronary Sinus = pouch that collects deoxygenatied blood from the coronary veins
Pulmonary Trunk
Superior
vena cava
Great
cardiac
vein
Anterior
cardiac
veins
Coronary
sinus
Small cardiac vein
Middle cardiac vein
(b) The major cardiac veins
Figure 18.7b

19. 6. Homeostatic Imbalances STUDENTS DO
*Angina pectoris
*Myocardial Infarction (heart attack)

20. 3. Umbilical Cord with Umbilical Artery and Veins
H. FETAL CIRCULATION
*Lungs are functional?
1. Alteration of Atrial
Blood Flow
Foramen Ovale
After Birth = Fossa
Ovalis
Alteration of Blood Flow
from Pulmonary Trunk
Ductus Arteriosis duct moves blood out of Pulmonary trunck
Ligamentum Arteriosum
3. Umbilical Cord with Umbilical Artery and Veins

21. I. Heart Valves 1. Function: prevent backflow of blood
2. * Atrioventricular (AV) valves—between what cavities?
*Bicuspid (mitral) valve __________ side
*Tricuspid valve ___________side
Parts: Cusps, Chordae Tendinae, Papillary muscles
*When ventricles contract: these valves do what?
Students Do

22. *Parts: Describe and give function
H. Heart Valves …
*Parts: Describe and give function
Cusps
Chordae Tendinae
Papillary muscles
*What happens to these valves when the atria and then the ventricles contract?

23. 3. Operation of the AV valves
H. Heart Valves …
3. Operation of the AV valves
Returning blood fills relaxed atria and ventricles– open AV valves
AV valves open
Ventricles
(a)
Figure 11.5a, step 1

24. Operation of the AV valves …
Returning blood fills relaxed atria and ventricles (open AV valves)
Atria contract – more blood forced into ventricles– AV valves still open
AV valves open
Relaxed
Ventricles
(a)
Figure 11.5a, step 2

25. Chordae tendineae prevent valve flaps from everting
Operation of the AV valves …
Chordae tendineae prevent valve flaps from everting
Ventricles contract, blood forced against AV flaps / into arteries
AV valves close preventing backflow to atria (LUB of LUB-dup sound)
(a)
Figure 11.5a, step 4

26. H. Heart Valves … 4. Semilunar valves Function:
Pulmonary semilunar valve – __R_side
Aortic semilunar valve – __L_side
*When Ventricles contract, what happens to valve?
3 cusps each
Figure 11.2c

27. 5. Operation of the semilunar valves
Aorta
As ventricles contract semilunar valves are forced open
Pulmonary trunk
Semilunar valve open
(b)
Figure 11.5b, step 1

28. All this to ensure that…
Operation of the semilunar valves …
As ventricles relax, blood flows back from arteries, forcing semilunar valves to close
All this to ensure that…
Aorta
Pulmonary trunk
Semilunar valve open
‘dup’ of LUB-dup sound
Semilunar valve closed
(b)
Figure 11.5b, step 2

29. II. Cardiac Muscle Fibers—Histology A
II. Cardiac Muscle Fibers—Histology A. Microscopic Anatomy of Cardiac Cells
*Review Skeletal Muscles (Text pages )
*Number of nuclei?
*Sarcolemma =
*Myofibrils =
*Sarcoplasmic Reticulum =
*Sarcomeres =
*T-tubules =
*Triads =
Sarcomere
Skeletal Muscle Cell
Thick Myofilaments
Thin Myofilaments
Myofibrils
Scaroplasmic Reticulum
T Tubules

30. A. Microscopic Anatomy of Cardiac Cells…
1. *Cardiac muscle cell characteristics: (text pp )
2. Endomysium anchored to: Fibrous Skeleton .
3. T tubules: Fewer Triads? None .
4. SR simpler  Source of Ca+2: from outside cell
5. Mitochondria: Many & Large to resist fatigue
Mitochondrion
Intercalated
disc
Cardiac
muscle cell
T tubule
Sarcoplasmic
reticulum
Z disc
Nucleus
Sarcolemma

31. A. Microscopic Anatomy of Cardiac Cells …
6. *Intercalated discs = Desmosomes (tight anchoring) & Gap Junctions (help electrical stimulation to move quickly from cell to cell)
7. Functional Syncytium: as a single coordinated unit
Autorhythmic Cells = Pace-Maker Cells: special self- excitable cardiac muscle cells
Function: stimulates heart contraction
8. Long Absolute Refractory Period
Function: to prevent tetany
Desmosomes
Gap junctions
Intercalated discs

32. III. Heart Physiology A. Mechanism and Events of Contraction
1. *Review of Skeletal Muscle Cells
*Depolarization-via AP
Proceeds down T tubules
Causing SR to
release Ca+2
*Repolarization occurs while
*Excitation-Contraction
Coupling occurs
Ca+2 attaches to Troponin
Myosin Cross-bridges form
Thin Myofilament slides inward
Sarcomeres shorten Cells shorten  Muscle shortens
*Na+-K+ pump redistributes ions & SR reabsorbs Ca+2

33. Have gap junctions between cells (intercalated discs)
2. Differences between skeletal and cardiac muscle contraction physiology– Cardiac cells have:
Have gap junctions between cells (intercalated discs)
Source of Ca+2: mostly extracellular through Ca+2 channels which then stimulate SR to release Ca+2
Supply of ATP: Aerobic Respiration only
No Tetany
Have Pace-Maker cells which initiate the contraction cycle
Cells contract together as a unit
Muscle Tension
Skeletal Fibers Cardiac Cells

34. 3. Mechanism and Events of Cardiac Cell Contraction
a. Stimulus: comes from Autorhythmic Cells  Pacemaker Potential
b. Action Potential– initiated by Pacemaker Potential
c. Depolarization in Cardiac Muscle Cells 1 in figure
i) Na+ channels open
ii) slow Ca2+ channels open 
iii) Influx of extracellular Ca2+ causes Depolarization
Na+
Slow Ca2+
Ca2+

35. d. Excitation- Contraction coupling
iv) Contraction begins as Ca+2 attaches to Troponin …
v) Plateau Phase
Ca+ channels slowly begin to close
Contraction
K+ channels closed
e. Repolarization
Ca channels close
K+ channels open
Ca+ pumped back to SR and extracellular
Muscle Contraction ends
Figure AP in Cardiac Muscle Cells
2 in figure 3
/Contraction
Cardiac Muscle
3 in figure

36. d. Excitation- Contraction coupling …
f. Hyperpolarization– NO g. Na-K+ Pump redistributes ions and SR reuptake Ca+2
Figure AP in Cardiac Muscle Cells 3
/Contraction
Cardiac Muscle

37. B. Electrical Pathway: 1. Setting the Basic Rhythum
III. Heart Physiology …
B. Electrical Pathway:
1. Setting the Basic Rhythum
a. Not Dependent on: Nerves
b. Intrinsic Conduction System
= Autorhythmic Cells: Non- Contractile & all linked together
In SA node, these cells have an unstable resting potential due to leaking in of Na+
Functions:
i) Initiate & Distribute Electrical Impulses
ii) Coordinate and Synchronize Cardiac contractions
SA Node
AV Node

38. 2. Sequence of Excitation
i) Sinoatrial (SA) node– Function: initiate contraction causing Atria to contract first
Location: superior Right Atrium
Intrinsic Rate: 100 = too fast: so vagus nerve slows it down to Normal 75 beats/min = Sinus Rhythm
Moves to: AV node
Atrioventricular (AV) node– functions: autorythmic cells are slow (0.1 s) to respond so Atria finish contracting
Location: Interatrial septum, inferiorly and just above Tricuspid Valve

39. 2. Sequence of Excitation …
iii) Atrioventricular Bundle = AV bundle (bundle of His) 
Location: Very short in: Interventricular Septum
iv) Bundle branches: carry impulses what direction: to bottom of Ventricles at Apex
Purkinje fibers:
Location: At apex and into Ventricular cardiac cells
Function: Delivers electrical stimulations to ventricles which results in their contraction

40. Action potential succession during one heartbeat.
Superior vena cava
Right atrium
sinoatrial (SA)
node (pacemaker)
generates impulses. 1
Internodal pathway
Impulses
pause (0.1 s) at
atrioventricular
(AV) node. 2
Left atrium
atrioventricular
(AV) bundle
connects atria
to ventricles. 3
Purkinje
fibers
bundle branches
conduct impulses thru
interventricular septum. 4
Inter-
ventricular
septum
Purkinje fibers
depolarize contractile
cells of both ventricles. 5
(a) Anatomy of the intrinsic conduction system showing the
sequence of electrical excitation

41. A. Electrical Events … 5. Electrocardiography
= Picks up: Electrical activity of contractile & non-contractile cardiac cells
i) Electrodes, Leads: pick up electrical activity
Clinically: 12 leads
ii) Electrocardiogram, ECG or EKG = 3-Lead: voltage difference between 2 points
Vertical axis = voltage amplitude
Horizontal axis = Time
Figure 18.6 Electrocardiogram
P =
QRS =
T =

42. An electrocardiogram (ECG a.k.a. EKG) tracing
QRS complex
Sinoatrial
node
Ventricular
depolarization
Ventricular
repolarization
Atrial
depolarization
Atrioventricular
node
S-T
Segment
P-Q
Interval
Q-T
Interval
0.1
Atria Contracting
Ventricles Contracting

43. Sequence of deflection waves of an ECG tracing
Depolarization R
Repolarization P T Q S
Ventricular depolarization is
complete. 4 R P T Q S
Ventricular repolarization begins
at apex, causing the T wave. 5 R P T Q S
Ventricular repolarization is
complete. 6

44. Electrocardiography …Waves & Intervals– sequence of
SA node
Depolarization
Repolarization P T Q S
Atrial depolarization, initiated by
the SA node, causes the P wave. 1 R
AV node P T Q S
With atrial depolarization complete,
the impulse is delayed at the AV node. 2 R P T Q S
Ventricular depolarization begins
at apex, causing the QRS complex.
Atrial repolarization occurs. 3

45. C. Heart Sounds: Valves Students do
Know:
Heart Murmur
Incompetent
Stenotic
Aortic valve sounds heard
in 2nd intercostal space at
right sternal margin
Pulmonary valve
sounds heard in 2nd
intercostal space at left
sternal margin
Mitral valve sounds
heard over heart apex
(in 5th intercostal space)
in line with middle of
clavicle
Tricuspid valve sounds typically
heard in right sternal margin of
5th intercostal space