Chap. 19 - The Heart (Cardiology)
Chap. 19 - The Heart (Cardiology)
Chap. 19 - The Heart (Cardiology)
19-1
Chap. 19 (Heart) Study Guide
1. Critically read Chapter 19 pp. 719-739 before
19.5 “Blood Flow” section
2. Comprehend Terminology (those in bold)
3. Study-- Figure questions, Think About It
questions, and Before You Go On (section-
ending) questions
4. Do Testing Your Recall— 1, 2, 4-8, 11-19
5. Do True or False– 1-4, 7, 9-10
6. Do Testing Your Comprehension-- #1
2
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
19-4
§ 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--
19-5
§ Two circuits in the
cardiovascular system (1)
1. Pulmonary circulation—
– Function?
– The route?
• R. ventricle Pulmonary arteries
Lungs Pulmonary veins L. atrium
Figure 19.1
19-6
Lungs
Pulmonary Pulmonary
capillaries circulation
Pulmonary Pulmonary
arteries veins
Right
side of
heart
19-7
§ Two circuits in the
cardiovascular system (2)
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
19-8
Systemic
circulation
Left side
= O2-poor blood
of heart
= O2-rich blood
Systemic
veins Systemic
arteries
Organ Systemic
systems capillaries 19-9
II. Gross anatomy of the heart
19-10
§ 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
19-11
Aorta
Superior
vena cava
Base of
heart
Apex of
heart
Next Topic
Diaphragm
19-12
§ Heart Position (1)
19-13
§ Heart Position (2)
19-14
§ Heart Position (3)
19-15
§ 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
16
here
Figure x
Pericardial
cavity
Heart
19-17
§ Pericardial sac (pericardium) - 2
1. Parietal pericardium– 2 SUBLAYERS
– A-outer, tough/fibrous layer (CT) + B-deep thin
serous layer– turns inward . . . forms #2 below
2. Visceral pericardium (a.k.a. epicardium of
heart wall)
– INNER, thin, smooth, moist serous layer
– covers heart surface
3. Pericardial cavity: between 1 + 2 above
– filled with ____________________
Fig. 19.3
19-18
Functions? 3
19-19
§ Heart Wall (from outermost layer)
1. Epicardium (a.k.a. visceral pericardium)
– serous membrane covers heart
2. Myocardium
– thick muscular layer
– fibrous skeleton - network of collagenous and
elastic fibers (special section for this one)
3. Endocardium - smooth inner lining
– What type of epi.? Simple _________ epi.
– Continuous with endothelium cells . . .
Fig. 19.3
19-20
2
3
1
19-21
§ Fibrous skeleton of the heart (1)
– What is it? Four CT rings fuse with . . .
Figure 19.8
19-22
(Rear)
Fibrous skeleton
Right AV valve including fibrous rings
Left AV valve
Aortic valve
Pulmonary semilunar
Ventricular valve
myocardium
19-23
(Front)
§ 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
19-24
Checkpoint Questions
1. Does most of the heart lie to
the right or left of the median
plane?
2. Name, in order, the three
layers of the heart wall
beginning with the outermost
layer.
19-25
§ Heart Chambers
• 4 chambers—
– A. right and left ATRIA
– auricles? Ear-like structures . . .
19-31
§ Heart valves (1)
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)
19-32
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 AV valve
Aortic/pulmonary
valve
19-34
Heart valves (2)
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 19-35
Right atrium
Chordae
tendineae
Right AV
valve
Direction of
backflow of Septum
blood
Right ventricle
Papillary
muscle
19-36
Right AV valve seen from within the
right ventricle
19-37
§ Heart valves (3)
3.Semilunar valves include: One
______ valve and one __________ valve
A. Where are they located respectively?
• Major arteries leave the ventricles
B. How to prevent them from everting?
• Anatomical structure— leakproof “seam”
C. Function– (of all valves)
• Ensure unidirectional flow of blood
Figure 19.7 and Fig. Z
19-38
Aorta Next slide
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
19-39
(Pulmonary trunk
or Aorta)
Direction of backflow of blood
Leakproof
“seam”
Aortic valve
(Right or Left
Ventricle)
19-40
§ 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 19-41
Operation of Atrioventricular Valves
S1
19-42
Operation of Semilunar Valves
S2
19-43
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. 19.9 is a great figure to
help you with this. 44
Fig. 19.9 Pathway of blood flow through the heart
Figure 19.10
III. The Coronary Circulation
19-46
§ Coronary arteries
2A
1A
19-49
1B
1C 2A
2B
19-50
§ Anastomoses of coronary arteries
1. Definition (Anastomosis) – a point where
two blood vessels join/merge; this is
arterial anastomoses
2. Where? Anterior interventricular branch
of LCA joins the posterior interventricular
branch of RCA
19-55
A
C
B
or posterior interventricular v. 19-56
IV. Cardiac conduction
system
19-57
§ 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
19-58
§ Cardiac Conduction System (1)
I. 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
II. Components
– next slide
19-59
Cardiac Conduction System (2)–
Autorhythmic cells
1. SA (sinoatrial) node: pacemaker, initiates
heartbeat, sets heart rate; where?
2. AV node: electrical gateway to ventricles;
where?
• fibrous skeleton– insulates atria from ventricle
3. AV bundle: pathway for signals from AV node
4. Right and left bundle branches: divisions of
AV bundle that enter interventricular septum
5. Purkinje fibers: upward from apex spread
throughout ventricular myocardium
19-60
Fig. 19.12 + X
Cardiac Conduction System
2
4
3
19-61
5
Students-- work on Interatrial
this one at home pathway
3. Atrioventricular
(AV) node
1. Sinoatrial
(SA) node 4. Bundle of His
or AV bundle
Right
atrium
5b. Left branch
2. Internodal
of bundle of His
pathway
Left
ventricle
5a. Right
branch
of bundle 6. Purkinje
Right fibers
of His ventricle 19-62
Checkpoint Question
Which chamber of the heart is first to
receive the electrical signal that
induces the heart to contract?
63
V. Cardiac muscle
19-64
§ Cardiac vs. skeletal m.(1)
Skeletal M. Cardiac M.
(cardiocyte)
Fibers & their •Fibers •Interlocking
control independent cells; (next)
•Voluntary •Involuntary
Nervous •Somatic motor • Autonomic
control by neurons nervous sys.
Initiation of •Requires input • by
contraction from motor autorhythmic
neurons cells in heart 65
§ Cardiac vs. skeletal m.(2)
1. Cardiac myocytes—size,
thickness etc.
Next slide
19-68
One myocyte is shown
(colored).
19-69
Structure of
2 an
1 intercalated
3
disc
Fascia adherens
72
§ Intercalated discs
3. Functions of gap junction (connexons):
• Allows action potentials to spread . . .
19-74
§ 19.4 Heart Autorhythmic Cells
1. Two types of cardiac muscle cells:
A. 1% are autorhythmic cells (our focus
on this section)–
– Function?
• AP— Yes
• Contraction– No
Figure 19.13
19-76
B
C
19-77
§ Heart autorhythmic cells
3. Details of pacemaker activity: (vs.
AP in nerve and skeletal m.):
A. 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
19-78
threshold
§ Heart autorhythmic cells
B. Rising phase of the action potential:
• Once, reach threshold p., long-
lasting Ca+2 channels open; . . .
• Influx of calcium ions
19-79
§ Heart autorhythmic cells
4.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.)
SA node 1st
beat
Internodal
pathway
AV node Bundle
of His
2nd
Purkinje beat
fibers
19-83
Our focus
19-84
§ Cardiac contractile cells
1. Action
potential is
initiated by:
the
pacemaker
cells
3 phases:
– Rising
– Plateau
–…
85
§ Cardiac contractile cells
2.The detail of action potential:
A.Rising phase
• Massive sodium ions influx causes
depolarization and AP
B.Plateau phase
• Primarily caused by opening of calcium
channels
• Also caused by temp. reduction in outflow of
_____________ ions
86
§ Cardiac contractile cells
C.Falling phase
87
Review slide— ID A, B, C, D, E below
A D
19-88
§ Cardiac contractile cells
Action Contractile
3.Contractile potential response
response
Compare to skeletal
muscle:
• Longer period of
cardiac contraction
• Longer refractory
period
How? Why? (next) Refractory
period
89
§ Cardiac contractile cells
A.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
Contractile
response
Action
potential
19-91
Stimulation
§ Cardiac contractile cells
B.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 . . .
T
P P
Q S
95
P
QRS
19-96