1. Chap. 19– The Heart (Cardiology)

2. Chap. 19 (Heart) Study Guide
Critically read Chapter 19 pp before 19.5 “Blood Flow” section
Comprehend Terminology (those in bold)
Study-- Figure questions, Think About It questions, and Before You Go On (section-ending) questions
Do Testing Your Recall— 1, 2, 4-8, 11-19
Do True or False– 1-4, 7, 9-10
Do Testing Your Comprehension-- #1 2 2

3. What are you going to do with your heart?
“The best and most beautiful things in the world cannot be seen or even touched—they must be felt with the heart.”
--Hellen Keller
“Happiness comes only when we push our brains and hearts to the farthest reaches of which we are capable.”
--Leo C. Rosten

4. I. Overview of cardiovascular system

5. § Introduction The circulatory system—
Three component: the pump, the passageway, and the transport medium
What are they respectively?
The pump--
The passageway--
The transport medium--

6. § Two circuits in the cardiovascular system (1)
Pulmonary circulation—
Function?
The route?
R. ventricle  Pulmonary arteries  Lungs  Pulmonary veins  L. atrium
Figure 19.1

7. Pulmonary circulation Right side of heart Lungs Pulmonary capillaries
veins
Pulmonary
arteries
= O2-poor blood
= O2-rich blood
Right side of
heart

8. § Two circuits in the cardiovascular system (2)
Systemic circulation—
Functions?
The route? (Students work on it.)
Starts which chamber of the heart?  Major vessels? Destinations?  Two major veins?  Ends at which chamber of the heart?
Fig. 19.1

9. Systemic circulation Left side of heart Systemic veins Systemic
= O2-poor blood
= O2-rich blood
Systemic
veins
Systemic
arteries
Systemic
capillaries
Organ
systems

10. II. Gross anatomy of the heart

11. § Shape and size of the heart
Base – broad superior portion
Apex - inferior end (a blunt point)
3.5 in. wide at base, 5 in. from base to apex, and 2.5 in. anterior to posterior
weighs 10 oz (300 gram; size of your fist)
Fig. 19.2

12. Aorta Superior vena cava Base of heart Apex of heart Diaphragm
Next Topic
Diaphragm

13. § Heart Position (1)

14. § Heart Position (2)

15. § Heart Position (3)

16. § Pericardial sac (pericardium) -1
Def. the double-walled, membranous covering that encloses the heart
Function– Friction free
Peircardial fluid— Figure x
Cardiac Disorders here (Table 19.3):
Pericarditis– inflammation here
Pericardial effusion– fluid in pericardial cavity
Cardiac tamponade– accumulation of fluid here

17. Figure x
Pericardial cavity
Heart

18. § Pericardial sac (pericardium) - 2
Parietal pericardium– 2 SUBLAYERS
A-outer, tough/fibrous layer (CT) + B-deep thin serous layer– turns inward forms #2 below
Visceral pericardium (a.k.a. epicardium of heart wall)
INNER, thin, smooth, moist serous layer
covers heart surface
Pericardial cavity: between above
filled with ____________________
Fig. 19.3

19. Functions? 3 1 2

20. § Heart Wall (from outermost layer)
Epicardium (a.k.a. visceral pericardium)
serous membrane covers heart
Myocardium
thick muscular layer
fibrous skeleton - network of collagenous and elastic fibers (special section for this one)
Endocardium - smooth inner lining
What type of epi.? Simple _________ epi.
Continuous with endothelium cells . . .
Fig. 19.3

21. 2 3 1

22. § Fibrous skeleton of the heart (1)
What is it? Four CT rings fuse with . . .
Structure details– Four fibrous rings, surrounds the 4 valves; in sheets of tissue that interconnect these rings
Location? In the walls between …
Figure 19.8

23. Fibrous skeleton including fibrous rings
(Rear)
Fibrous skeleton including fibrous rings
Right AV valve
Left AV valve
Aortic valve
Pulmonary semilunar
valve
Ventricular
myocardium
(Front)

24. § Fibrous skeleton of the heart (2)
Functions–
1. Structure support-- firm base of the heart valves and openings of great vessels
2. It anchors the cardiac muscle
3. An electrical insulator:
Separate the atria from the ventricles and direct A.P. to specific pathways

25. Checkpoint Questions
Does most of the heart lie to the right or left of the median plane?
Name, in order, the three layers of the heart wall beginning with the outermost layer.

26. § Heart Chambers 4 chambers— 3 sulci (grooves)— on the surface
A. right and left ATRIA
auricles? Ear-like structures . . .
B. right and left VENTRICLES
3 sulci (grooves)— on the surface
Largely fat and coronary blood vessels
A. Atrioventricular (coronary) sulcus-
B+C. Anterior and posterior interventricular sulci
Figure 19.5 a+b

27. Coronary sulcus?
Anterior view

28. Posterior view

29. § Heart Chambers – Internal (Fig. 19.7)
Interatrial septum
wall that separates atria
Pectinate muscles
internal ridges of myocardium in right atrium and both auricles; absorber)
Interventricular septum
wall that separates ventricles
Trabeculae carneae
internal ridges in both ventricles absorber)
Wave/sound absorber

31. Checkpoint Questions
Which heart chamber has the thickest walls? What is the significance of this structural difference?
Do the atrial pectinate muscles more nearly resemble the ventricular papillary muscles or the trabeculae carneae?

32. blood from the atria to ventricles . . .
§ Heart valves (1)
Two atrioventricular (AV) valves—
A. Right AV valve– also called the tricuspid valve
B. Left AV valve– also called . . .
Function--
blood from the atria to ventricles . . .
Figure 19.8 (a,b)

33. Superior views of these valves – next slide
Aorta
Pulmonary artery
Superior vena cava
Pulmonary valve
Pulmonary veins
Pulmonary veins
Left atrium
Left AV valve
Right atrium
Aortic valve
Chordae tendineae
Right AV valve
Papillary muscle
Left ventricle
Right ventricle
Interventricular septum
Inferior vena cava
Superior views of these valves – next slide

34. Right AV valve Left AV valve
Aortic/pulmonary valve

35. Heart valves (2) Chordae tendineae— Structure–
Fibrous cords anchor the cusps to the ventricle walls via papillary muscles
Function–
Prevent valves from being _________
Figure 19.7, 19.8

36. Right atrium
Chordae tendineae
Right AV valve
Direction of
backflow of
blood
Septum
Right ventricle
Papillary muscle

37. Right AV valve seen from within the right ventricle

38. § Heart valves (3)
Semilunar valves include: One ______ valve and one __________ valve
Where are they located respectively?
Major arteries leave the ventricles
How to prevent them from everting?
Anatomical structure— leakproof “seam”
Function– (of all valves)
Ensure unidirectional flow of blood
Figure 19.7 and Fig. Z

39. Next slide Aorta Pulmonary artery Pulmonary valve Aortic valve
Superior vena cava
Pulmonary valve
Pulmonary veins
Pulmonary veins
Left atrium
Left AV valve
Right atrium
Aortic valve
Chordae tendineae
Right AV valve
Papillary muscle
Left ventricle
Right ventricle
Interventricular septum
Inferior vena cava

40. (Pulmonary trunk or Aorta) (Right or Left Ventricle)
Direction of backflow of blood
Leakproof
“seam”
Aortic valve
(Right or Left Ventricle)

41. § Valve Mechanics (Fig. 19.9, 19.19)
Ventricles filling & isovolumetric contraction
AV valves open (semilunar valves close); blood flows from atria to ventricles (v. fillings)
AV valves open/closed (circle one)—S1
ventricle pressure continues to rise
Momentarily before ventricle ejection
Ventricles ejection & isovolumetric relaxation
semilunar valves open (AV valves close);
ventricle ejection; ventricle pressure drops
semilunar valves open/closed (circle one)—S2
Isovolumetric relaxation

42. Operation of Atrioventricular Valves

43. Operation of Semilunar Valves

44. Before You Go On (p. 730)
Reminder: Remember to go over each question of Before You Go On in the text.
P. 730– Trace the flow of blood through the heart, naming each chamber, valve, and the great vessels in order (from the superior vena cava to the aorta). Do it yourself. Fig is a great figure to help you with this. \

45. Fig. 19.9 Pathway of blood flow through the heart
Figure 19.10
Fig Pathway of blood flow through the heart

46. III. The Coronary Circulation

47. § Coronary arteries
Right C.A.
Left C.A.

48. § Coronary Arterial Supply
1. Left coronary artery (LCA)– 2 branches
1A--anterior interventricular branch
supplies blood to interventricular septum and anterior walls of both ventricles
1B--circumflex branch (Fig a+b)
passes around left side of heart in coronary sulcus, supplies left atrium and posterior wall of left ventricle; it gives off a left marginal branch (1C)
2. Right coronary artery (RCA)– 2 branches
2A--right marginal branch
supplies lateral side of R atrium and ventricle
2B--posterior interventricular branch
supplies posterior walls of ventricles

49. 1B 2A 1A

50. 1B 1C 2A 2B

51. § Anastomoses of coronary arteries
Definition (Anastomosis) – a point where two blood vessels join/merge; this is arterial anastomoses
Where? Anterior interventricular branch of LCA joins the posterior interventricular branch of RCA
Function– provide collateral (alternative) routes of blood supply to a tissue (the heart)
Fig. x

53. Chest pain and Heart Attack
Angina pectoris--
partial obstruction of coronary blood flow can cause chest pain
pain caused by ischemia, often activity dependent
Myocardial infarction (heart attack)--
complete obstruction causes death of cardiac cells in affected area
pain or pressure in chest that often radiates down left arm

54. § Venous Drainage of Heart
10% drains directly into right atrium and ventricle via multiple thebesian veins
90% returns to right atrium via: (Fig )
A. great cardiac vein
blood from anterior interventricular sulcus
B. middle cardiac vein (post. interventricular v.)
from posterior sulcus
C. left marginal vein
The above three (A, B, C) empty into the coronary sinus before emptying into the ____________ (which chamber of the heart?)

55. A

56. A C B
or posterior interventricular v.

57. IV. Cardiac conduction system

58. § 19.3 Cardiac muscle & conduction system
Heart has its own pacemaker, nerves MODIFY the heart rate & contraction strength.
Beat rhythmically, _________beats per min.
Pacemaker? Where? (next slide)
Myogenic and autorhythmic
Regulation by autonomic nerve system

59. § Cardiac Conduction System (1)
Properties
myogenic - heartbeat originates from within ____________________
Originated from what cells (1% of heart cells)?
cardiac muscles become specialized into autorhythmic cells (cardiac conduction system)
What do autorhythmic cells do?–
regular, spontaneous depolarization
Components
next slide

60. Cardiac Conduction System (2)– Autorhythmic cells
SA (sinoatrial) node: pacemaker, initiates heartbeat, sets heart rate; where?
AV node: electrical gateway to ventricles; where?
fibrous skeleton– insulates atria from ventricle
AV bundle: pathway for signals from AV node
Right and left bundle branches: divisions of AV bundle that enter interventricular septum
Purkinje fibers: upward from apex spread throughout ventricular myocardium
Fig X

61. Cardiac Conduction System1 2 4 3 5

62. Students-- work on this one at home
Interatrial
pathway
3. Atrioventricular
(AV) node
1. Sinoatrial
(SA) node
4. Bundle of His or AV bundle
Right
atrium
5b. Left branch
of bundle of His
2. Internodal
pathway
Left
ventricle
5a. Right
branch
of bundle
of His
6. Purkinje
fibers
Right
ventricle

63. Checkpoint Question
Which chamber of the heart is first to receive the electrical signal that induces the heart to contract?

64. V. Cardiac muscle

65. § Cardiac vs. skeletal m.(1)
Cardiac M. (cardiocyte)
Fibers & their control
Fibers independent
Voluntary
Interlocking cells; (next)
Involuntary
Nervous control by
Somatic motor neurons
Autonomic nervous sys.
Initiation of contraction
Requires input from motor neurons
by autorhythmic cells in heart

66. § Cardiac vs. skeletal m.(2)
Cardiac myocytes—size, thickness etc.
T (transverse) tubules– smaller
Presence of intercalated discs– (see next slide)
Mitochondria—
Myoglobin and glycogen--

67. § Intercalated discs (of cardiac muscle cells)
Def. specialized zigzag structures joining cardiac muscle cells end to end
Containing three distinctive features not found in skeletal muscle; what are they?
Figure a-c

68. Figure 19.11a light micrograph
Next slide

69. One myocyte is shown (colored).

70. Structure of an intercalated disc2 1 3
1-- interdigitating folds
2—mechanical junctions– two types; fascia adherens and desmosomes
3—electrical (gap) junctions--

71. Desmosome Fascia adherens Plasma membranes of adjacent
cardiac muscle fibers
Desmosome
Fascia adherens
Action
potential
Gap junction
Intercalated disc

72. § Intercalated discs Function of interdigitating folds--
Functions of fascia adherens and desmosome –
Types of adhering junction
Mechanically, hold cells together

73. § Intercalated discs Functions of gap junction (connexons):
Allows action potentials to spread . . .
Therefore, cardiac cells form functional syncytia— cardiac cells excited and contract as a single unit
Q--Does the atria and the ventricle each form a separate unit?

74. VI. Electrical activity of heart (autorhythmic cells)

75. § 19.4 Heart Autorhythmic Cells
Two types of cardiac muscle cells:
1% are autorhythmic cells (our focus on this section)–
Function?
AP— Yes
Contraction– No
99% --contractile cells
AP— No initiation of own Action Potential
Contraction– Yes

76. § Heart autorhythmic cells
Autorhythmic cells act as pacemaker:
How? Their m. potential slowly depolarizes (drifts) between AP, until …
Figure 19.13

77. Pacemaker potentials & action potentials of the SA nodeB C A
Pacemaker potentials & action potentials of the SA node

78. § Heart autorhythmic cells
Details of pacemaker activity: (vs. AP in nerve and skeletal m.):
Slow depolarization:
i. K+ voltage-gated channels slowly close
ii. (No voltage-gated Na+ channels), instead sodium leak channels are used; So, sodium ions move in/out
iii. Transient Ca+2 channels open—Calcium ions move inward
All these make the inside becomes depolarized Thus, pacemaker p. toward threshold

79. § Heart autorhythmic cells
Rising phase of the action potential:
Once, reach threshold p., long-lasting Ca+2 channels open; . . .
Influx of calcium ions
The falling phase:
as usual, potassium ions efflux

80. § Heart autorhythmic cells
Autorhythmic cells are self excitable:
Without nervous stimulation
They initiate AP cyclically, which trigger rhythmic beating
Each depolarization of SA node sets off one heartbeat (every 0.8 sec.)
They form the conduction system of the heart (see Figure 19.12)
It excites the other components in the system

81. § Heart autorhythmic cells
The spread of cardiac excitation:
In a coordinated sequence:
A-First, atrial excitation– From SA node to atria; How? through gap junctions; via internodal and interatrial pathways as well; Result– a single smooth contraction of the pair of atria (Fig. Y)
B-Second, from the atria to the ventricles—
AV node is the only point of electrical contact from the atria to the ventricles
C-Finally, ventricular excitation--
from AV node to the bundle of His, . . .
Result– a single smooth contraction in ventricles

82. Interatrial pathway 1st beat SA node Internodal pathway Bundle AV node
Right atrium
Left atrium
1st beat
SA node
Internodal
pathway
Bundle
of His
AV node
2nd beat
Purkinje
fibers
Right ventricle
Left ventricle

83. VII. contractile activity of heart

84. Our focus

85. § Cardiac contractile cells
Action potential is initiated by: the pacemaker cells
3 phases:
Rising
Plateau …

86. § Cardiac contractile cells
The detail of action potential:
Rising phase
Massive sodium ions influx causes depolarization and AP
Plateau phase
Primarily caused by opening of calcium channels
Also caused by temp. reduction in outflow of _____________ ions

87. § Cardiac contractile cells
Falling phase
Primarily caused by ____________ outflow
Closing of calcium channels contribute to this as well

88. Review slide— ID A, B, C, D, E below

89. § Cardiac contractile cells
Action potential
Contractile response
Contractile response
Compare to skeletal muscle:
Longer period of cardiac contraction
Longer refractory period
How? Why? (next)
Refractory period

90. § Cardiac contractile cells
Longer period of cardiac contraction
3x longer compared to skeletal m.
Caused by entry of calcium ions which induce more calcium ions release from the sarcoplasmic reticulum
Purpose– this increased contractile time ensures emptying blood into ventricles and arteries
Fig (skeletal muscle)

91. In skeletal muscle Latent period Contraction time Relaxation time
twitch
Contractile
response
Action
potential
Stimulation

92. § Cardiac contractile cells
Longer refractory period
Caused chiefly by inactivation of the sodium ion channels
Consequences/Purpose– Cardiac muscle cannot be re-stimulated until contraction is almost over, therefore summation and tetanus of cardiac m. is impossible
This ensures . . .
Compared to Fig (Shown previously; in skeletal m.)

93. § ECG (Electrocardiogram)
Def. A record of the overall electrical activity in all the cardiac muscle cells from the body surface
NOT a recording of a single action potential in a single cell
ECG recording represents . . .electrical activity detected by electrodes at 2 different points
Figure (ECG)

95. § ECG (Electrocardiogram)
Components of the ECG correlate to cardiac events (Fig in the next slide)
P wave— atrial depolarization when the electrical impulse spreads across the atria
QRS complex—
T wave— ventricular repolarization R T P P Q S

96. P T
QRS