Transcript PowerPoint to accompany - shsbiology / FrontPage

Chapter 15
Cardiovascular System
1
Size of Heart
Average Size of Heart
• 14 cm long
• 9 cm wide
2
Heart
• Hollow, fist-sized muscular
organ
• Located slightly to left of
body’s midline
• Acts as dual pumping system
3
Location of Heart
• posterior to sternum
• medial to lungs
• anterior to vertebral column
• base lies beneath 2nd rib
• apex at 5th intercostal space
• lies upon diaphragm
4
Coverings of Heart
5
Pericardium
• Fibrous sac that covers heart
–2 portions
–Fibrous pericardium-external sac
• Tough, white, fibrous tissue; fits
loosely around heart
• Protects heart & serous membrane
–Serous pericardium: internal sac
6
Serous Layer
• Serous layer - a smooth inner sac with
lubricated surfaces which allow movement
– parietal layer - lines the inner surface of
the fibrous pericardium
– visceral layer - covers the entire surface
of the heart
• The potential space between the parietal
and visceral layers of the serous
pericardium is the pericardial cavity.
7
8
9
10
*Image courtesy Indigo Instruments. Visit indigo.com for
more original content like this.
11
Heart Wall: Layers
•Endocardium
•Myocardium
• Epicardium
12
13
14
Wall of the Heart
15
Wall of the Heart
16
Heart Chambers
Right Atrium
• receives blood from
• inferior vena cava
• superior vena cava
• coronary sinus
Right Ventricle
• receives blood from
right atrium
Left Atrium
• receives blood from
pulmonary veins
Left Ventricle
• receives blood from
left atrium
17
Heart Valves
18
Coronal Sections of Heart
19
Heart Valves
Tricuspid Valve
Pulmonary and Aortic Valve
20
Skeleton of Heart
• fibrous rings to which the heart valves are attached
21
Path of Blood
Through the Heart
22
Path of Blood
Through the Heart
23
Blood Supply to Heart
24
Blood Supply to Heart
25
Angiogram of Coronary Arteries
26
Heart Actions
Atrial Systole/Ventricular Diastole
Atrial Diastole/Ventricular Systole
27
Cardiac Cycle
Atrial Systole/Ventricular Diastole
• blood flows passively into ventricles
• remaining 30% of blood pushed into ventricles
• A-V valves open/semilunar valves close
• ventricles relaxed
• ventricular pressure increases
28
Cardiac Cycle
Ventricular Systole/Atrial diastole
• A-V valves close
• chordae tendinae prevent cusps of valves from
bulging too far into atria
• atria relaxed
• blood flows into atria
• ventricular pressure increases and opens semilunar
valves
• blood flows into pulmonary trunk and aorta
29
Heart Sounds
Lubb
• first heart sound
• occurs during ventricular systole
• A-V valves closing
Dupp
• second heart sound
• occurs during ventricular diastole
• pulmonary and aortic semilunar valves closing
Murmur – abnormal heart sound
30
Heart Sounds
31
Cardiac Conduction System
32
Cardiac Conduction & Control
• Intrinsic: internally generated
control
• Extrinsic: control from outside heart
• Heart rate controlled by both
– A.N.S.: can fine tune heart
– S.N.S.-can accelerate heart rate
– P.S.-can slow heart rate
– Hormones-can influence heart rate ex.
epinephrine
33
Intrinsic Control
• Sinoatrial node (S.A)
• Atrioventricular Node (A.V.)
• Bundle of His
• Purkinje Fibers
34
Sinoatrial Node
• The natural pacemaker of the heart
• Location - junction of superior vena cava and
right atrium
• Impulse for contraction begins at the SA node
and are conducted to the AV node by atrial
mycardial fibers (internodal tracts)
• The SA node is supplied by both divisions of the
ANS
35
Atrioventricular Node
• Located in lower right
interatrial septum
• Impulse slows
• Slowing allows atria to
contract & ventricle to fill
with blood
36
37
Bundle of His
• Originates in AV. Node
• Divides into left and right
branches
• Impulse from AV. Continues
into left and right bundle
branches
38
Purkinje Fibers
• Connect bundle branches to lateral
walls of ventricle
• Impulse moves through Purkinje fibers
reaching ventricle muscles
• Stimulation of ventricle muscles begins
in intraventricular septum & moves
downward
• Depolarization of ventricles &
contraction
39
40
41
42
43
44
45
46
47
Cardiac Conduction System
48
Electrocardiogram
• recording of electrical changes that occur in the myocardium
• used to assess heart’s ability to conduct impulses
P wave – atrial depolarization
QRS wave – ventricular depolarization
T wave – ventricular repolarization
49
Electrocardiogram
50
Electrocardiogram
A prolonged QRS complex may result from damage to the A-V
bundle fibers
51
Cardiac Cycle
52
Clinical Application
Arrhythmias
Ventricular fibrillation
• rapid, uncoordinated
depolarization of ventricles
Tachycardia
• rapid heartbeat
Atrial flutter
• rapid rate of atrial
depolarization
53
Regulation of Cardiac Cycle
Autonomic nerve impulses alter the
activities of the S-A and A-V nodes
54
Regulation of Cardiac Cycle
Additional Factors that Influence HR
• physical exercise
• body temperature
• concentration of various ions
• potassium
• calcium
• parasympathetic impulses decrease heart action
• sympathetic impulses increase heart action
• cardiac center regulates autonomic impulses to the heart
55
56
Blood Vessels
• arteries
• carry blood away from ventricles of heart
• arterioles
• receive blood from arteries
• carry blood to capillaries
• capillaries
• sites of exchange of substances between
blood and body cells
• venules
• receive blood from capillaries
• veins
• carry blood toward ventricle of heart
57
Arteries
Artery
• thick strong wall
• endothelial lining
• middle layer of smooth
muscle and elastic tissue
• outer layer of connective
tissue
• Carry blood away from
heart
•Vascular resistance low
•Mean arterial pressure =
100mmHg
58
59
Arterioles
Arterioles
• thinner wall than artery
• endothelial lining
• some smooth muscle
tissue
• small amount of
connective tissue
• helps control blood flow
into a capillary
• Mean pressure =85mmHg
60
Arteriole
• smallest arterioles only have a few smooth muscle fibers
• capillaries lack muscle fibers
61
Venules
Venule
• thinner wall than arteriole
• less smooth muscle and elastic tissue than arteriole
•Carry blood away from capillaries to veins
•BP 15mmHg when blood returning to heart
62
Veins
Vein
• thinner wall than artery
• three layers to wall but middle layer is poorly developed
• serves as blood reservoir
•Carry blood from venules to heart
• have valves =prevent backflow of blood
•Mean pressure =less than 15mmHg
63
64
65
66
Walls of Artery and Vein
67
Capillaries
• smallest diameter blood vessels
• extensions of inner lining of arterioles
• walls are endothelium only; single layer
• semipermeable
• sinusoids – leaky capillaries
•Join arterioles & venules
•Vascular resistance low = 35mmHg
68
Capillary Network
69
70
Exchange in the Capillaries
• water and other substances leave capillaries because of net outward pressure
at the capillaries’ arteriolar ends
• water enters capillaries’ venular ends because of a net inward pressure
• substances move in and out along the length of the capillaries according to
their respective concentration gradients
71
Venous Valves
72
Characteristics of Blood Vessels
73
Blood Volumes in Vessels
74
Arterial Blood Pressure
Blood Pressure – force the blood exerts against the
inner walls of the blood vessels
Arterial Blood Pressure
• rises when ventricles contract
• falls when ventricles relax
• systolic pressure – maximum pressure
• diastolic pressure – minimum pressure
75
Pulse
• alternate expanding and recoiling of the arterial wall
that can be felt
76
Factors That Influence
Arterial Blood Pressure
77
Control of Blood Pressure
Controlling cardiac output and peripheral resistance
regulates blood pressure
78
Control of Blood Pressure
If blood pressure rises, baroreceptors initiate the
cardioinhibitory reflex, which lowers the blood pressure
79
Control of Blood Pressure
Dilating arterioles helps regulate blood pressure
80
Venous Blood Flow
• not a direct result of heart
action
• dependent on
• skeletal muscle
contraction
• breathing
• venoconstriction
81
Pulmonary Circuit
• consists of vessels that carry blood from the heart to the lungs
and back to the heart
82
Blood Flow Through Alveoli
• cells of alveolar wall are tightly joined together
• the high osmotic pressure of the interstitial fluid draws
water out of them
83
Systemic Circuit
• composed
of vessels that lead from the
heart to all body parts (except the lungs)
and back to the heart
• includes the aorta and its branches
• includes the system of veins that return
blood to the right atrium
84
Major Vessels of Arterial System
85
Abdominal Aorta and Its Major
Branches
86
Arteries to Neck, Head, and
Brain
87
Cerebral Arterial Circle
• Circle of Willis
• formed by anterior and posterior cerebral arteries, which
join the internal carotid arteries
88
Arteries to Shoulder
and Upper Limb
89
Arteries to the Lower Limb
90
Major Vessels of the Venous
System
91
Major Veins of the Brain, Head
and Neck
92
Veins from the Upper Limb and
Shoulder
93
Veins That Drain the Thoracic
Wall
94
Veins That Drain the Abdominal
Viscera
95
Veins of the Lower Limb and
Pelvis
96
Life-Span Changes
• cholesterol deposition in blood vessels
• heart enlargement
• death of cardiac muscle cells
• increase in fibrous connective tissue of the heart
• increase in adipose tissue of the heart
• increase in blood pressure
• decrease in resting heart rate
97