Circulation

1
The Circulatory System
Ch 18
2
Components of the Human Circulatory System

• The Heart
• Blood Vessels
• Blood
• Lymphatic Vessels
• Lymph

3
Functions of the Circulatory System

• Transport oxygen to cells
• Transport nutrients from the digestive system to
  body cells
• Transport hormones to body cells
• Transport waste from body cells to excretory
  organs
• Distribute body heat

4

• Energy Requirements
• lots of mitochondria
• aerobic respiration

5

• Mechanisms and events of contractions
• All or none law- at organ level, not cellular
  level
• Means of stimulation- autorhythmicy
• Length of refractory period- cardiac (250ms),
  skeletal (1-2ms)

6
Location of Heart
Location of Heart
7
Layers of Cardiac Tissue

• Visceral pericardium
• Outer protective layer composed of a serous
  membrane
• Includes blood capillaries, lymph capillaries,
  and nerve fibers.

8
Layers of Cardiac Tissue

• Myocardium
• Relatively thick.
• Consists largely of cardiac muscle tissue
  responsible for forcing blood out of the heart
  chambers.
• Muscle fibers are arranged in planes, separated
  by connective tissues that are richly supplied
  with blood capillaries, and nerve fibers.

9
Layers of Cardiac Tissue

• Endocardium
• Consists of epithelial and connective tissue that
  contains many elastic and collagenous fibers.
• Connective tissue also contains blood vessels and
  some specialized cardiac muscle fibers called
  Purkinje fibers.
• Lines all of the heart chambers and covers heart
  valves.

10
Pericardial Cavity
11
Layers of Cardiac Tissue
12
Heart Anatomy
13
Heart Anatomy
14
Heart Anatomy
http//www.youtube.com/watch?vtBQa8IBzP6I
15
Heart Anatomy
Left ventricle
Right ventricle
Interventricular septum
16
Circulation
17
Mechanisms Events of Contraction

• Means of stimulation
• Organ vs motor unit contraction
• Length of absolute refractory period

18
Microscopic Anatomy of Cardiac Muscle

• Cardiac muscle cells are striated, short, fat,
  branched, and interconnected
• Connective tissue matrix (endomysium) connects to
  the fibrous skeleton
• T tubules are wide but less numerous SR is
  simpler than in skeletal muscle
• Numerous large mitochondria (2535 of cell
  volume)

19
Nucleus
Intercalated discs
Cardiac muscle cell
Desmosomes
Gap junctions
(a)
Figure 18.11a
20
Microscopic Anatomy of Cardiac Muscle

• Intercalated discs junctions between cells
  anchor cardiac cells
• Desmosomes prevent cells from separating during
  contraction
• Gap junctions allow ions to pass electrically
  couple adjacent cells
• Heart muscle behaves as a functional syncytium

21
Microscopic Anatomy of Cardiac Muscle
22
Microscopic Anatomy of Cardiac Muscle
23
VALVES
Pulmonary valve
Myocardium
Aortic valve
Tricuspid (right atrioventricular) valve
Area of cutaway
Mitral valve
Tricuspid valve
Mitral (left atrioventricular) valve
Myocardium
Tricuspid (right atrioventricular) valve
Aortic valve
Mitral (left atrioventricular) valve
Pulmonary valve
Aortic valve
Pulmonary valve
Aortic valve
Pulmonary valve
Area of cutaway
(b)
Fibrous skeleton
Mitral valve
Tricuspid valve
(a)
Anterior
Figure 18.8a
24
VALVES
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Chordae tendineae attached to tricuspid valve flap
Papillary muscle
(c)
Figure 18.8c
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pulmonary arteries
aorta
pulmonary arteries
pulmonary vein
superior vena cava
left atrium
left ventricle
inferior vena cava
right ventricle
28
Heart Valves
29
Contraction Cycle of the Heart
30
Contraction Cycle of the Heart
31
Contraction Cycle of the Heart
32
Cardiac Output
CO the vol. of blood ejected from the l. or r.
ventricle into the aorta or pulmonary trunk each
min. CO SV x HR SV stroke vol. the vol of
blood ejected from the ventricle during each
contraction (ml/beat) HR heart rate
beats/min, at rest 60, exercise 100
33
Cardiac Output (at rest)
SV 75 ml/beat HR 75 beats/min CO 75 ml/b
x 75 b/min CO 5250 ml/min 5.25 L/min
34
Cardiac Output (exercise)
SV 100 ml/beat HR 100 beats/min CO 100
ml/b x 100 b/min CO 10 L/min
35
Electrical Conductivity of the Heart
36
Nerve Innervation
pons
Vagus nerve from medulla (parasympathetic
division) ? acetylcholine (slows heart)
Cardioacceleratory center in medulla
(sympathetic) ? adrenaline from adrenal glands
(speeds up heart)
medulla oblongata
vagus
37
Electrocardiogram (ECG)
0.1 sec
0.3 sec
0.4 sec

• P atrial depolarization 0.1 sec atria
  contracts
• QRS ventricular depolarization ?ventricles
  contract (lub), contraction stimulated by Ca
  uptake
• T ventricular repolarization ? ventricles relax
  (dub)

38
Excitation of the Heart
R
Depolarization
SA node
Repolarization
T
P
Q
S
1
Atrial depolarization, initiated bythe SA
node, causes the P wave.
Figure 18.17, step 1
39
R
Depolarization
SA node
Repolarization
T
P
Q
S
1
Atrial depolarization, initiated bythe SA
node, causes the P wave.
R
AV node
T
P
Q
S
2
With atrial depolarization complete,the
impulse is delayed at the AV node.
Figure 18.17, step 2
40
R
Depolarization
SA node
Repolarization
T
P
Q
S
1
Atrial depolarization, initiated bythe SA
node, causes the P wave.
R
AV node
T
P
Q
S
2
With atrial depolarization complete,the
impulse is delayed at the AV node.
R
T
P
Q
S
Ventricular depolarization beginsat apex,
causing the QRS complex.Atrial repolarization
occurs.
3
Figure 18.17, step 3
41
Depolarization
Repolarization
R
T
P
Q
S
Ventricular depolarization iscomplete.
4
Figure 18.17, step 4
42
Depolarization
Repolarization
R
T
P
Q
S
Ventricular depolarization iscomplete.
4
R
T
P
Q
S
Ventricular repolarization beginsat apex,
causing the T wave.
5
Figure 18.17, step 5
43
Depolarization
Repolarization
R
T
P
Q
S
Ventricular depolarization iscomplete.
4
R
T
P
Q
S
Ventricular repolarization beginsat apex,
causing the T wave.
5
R
T
P
Q
S
Ventricular repolarization iscomplete.
6
Figure 18.17, step 6
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(a) Normal sinus rhythm.
(b) Junctional rhythm. The SA node is
nonfunctional, P waves are absent, and
heart is paced by the AV node at 40 - 60
beats/min.
(d) Ventricular fibrillation. These
chaotic, grossly irregular ECG deflections
are seen in acute heart attack and
electrical shock.
(c) Second-degree heart block. Some P waves
are not conducted through the AV node
hence more P than QRS waves are seen. In
this tracing, the ratio of P waves to
QRS waves is mostly 21.
Figure 18.18
45
Heart Sounds

• Two sounds (lub-dup) associated with closing of
  heart valves
• First sound occurs as AV valves close and
  signifies beginning of systole
• Second sound occurs when SL valves close at the
  beginning of ventricular diastole
• Heart murmurs abnormal heart sounds most often
  indicative of valve problems

46
Coronary Artery Disease(CAD)

• Arteriosclerosis
• HDL vs LDL

47
Homeostatic Imbalances

• Angina pectoris
• Thoracic pain caused by a fleeting deficiency in
  blood delivery to the myocardium
• Cells are weakened
• Myocardial infarction (heart attack)
• Prolonged coronary blockage
• Areas of cell death are repaired with
  noncontractile scar tissue

http//www.youtube.com/watch?vl36zIKP53Ls
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Coronary Artery Disease(CAD) Diagnosis

• Stress test
• Echocardiography
• http//youtu.be/DuanD-z45tw
• Cardiac catheterization
• Coronary angiography

49
Cardiac Catheterization
50
Coronary Artery Disease(CAD) Treatment

• Coronary bypass grafting (CABG)
• Percutaneous transluminal coronary angioplasty
  (PTCA)

51

• Coronary bypass grafting (CABG)

52

• Percutaneous transluminal coronary angioplasty
  (PTCA)

53
Automated External Defibrillator AED
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Heart Anatomy
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Inquiry

1. Name the 2 pacemakers of the heart.
2. What is the QRS wave?
3. What is the middle layer of heart tissue called?
4. What is the parietal pericardium?
5. Why is the left ventricle thicker walled than the
   right?
6. What blood vessel returns blood from the lungs to
   the heart?
7. What is the function of the chordae tendinae?
8. How does the heart avoid going into tetanus?
9. What function does serous fluid serve?