Download Heart Anatomy - Dr. M`s Class

Cardiovascular System Notes:
The Heart
Interesting Cardiovascular System Facts
The human heart creates
enough pressure to squirt
blood 30 feet.
NOTES – THE HEART
• Location:
• cavity between the lungs, 2/3 left of
midsagittal
• roughly the size of a fist
Figure 18.2b Location of the heart in the mediastinum.
Mediastinum
Heart
Left lung
Body of T7
vertebra
Posterior
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Figure 18.2c Location of the heart in the mediastinum.
Superior
vena cava
Pulmonary
trunk
Aorta
Parietal pleura
(cut)
Left lung
Pericardium (cut)
Apex of heart
Diaphragm
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• Heart Anatomy
• PERICARDIUM
• outer membrane of the heart
• 2 layers
1. Parietal pericardium: external
(outer) layer
2. Visceral pericardium (epicardium):
part of the heart wall
• Functions:
• protection – physical barrier
• anchors heart to other structures
• provides lubrication to reduce
friction – allows the heart to beat
easily
• THE HEART WALL
• 3 layers
1. Epicardium: outer portion
(visceral pericardium)
EPICARDIUM
2. Myocardium: middle layer
consists of twisted cardiac
muscle
MYOCARDIUM
• THIS IS THE LAYER THAT
ACTUALLY CONTRACTS
3. Endocardium: inner layer
made of epithelial tissue
ENDOCARDIUM
Figure 18.3 The pericardial layers and layers of the heart wall.
Pulmonary
trunk
Fibrous pericardium
Pericardium
Parietal layer of serous
pericardium
Myocardium
Pericardial cavity
Epicardium (visceral
layer of serous
pericardium)
Myocardium
Endocardium
Heart chamber
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Heart
wall
Homeostatic Imbalance
• Pericarditis
– Inflammation of pericardium
– Roughens membrane surfaces  pericardial
friction rub (creaking sound) heard with
stethoscope
– Cardiac tamponade
• Excess fluid sometimes compresses heart 
limited pumping ability
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The Pulmonary and Systemic Circuits
• Receiving chambers of heart:
– Right atrium
• Receives blood returning from systemic circuit
– Left atrium
• Receives blood returning from pulmonary circuit
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The Pulmonary and Systemic Circuits
• Pumping chambers of heart:
– Right ventricle
• Pumps blood through pulmonary circuit
– Left ventricle
• Pumps blood through systemic circuit
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Figure 18.1 The systemic and pulmonary circuits.
Capillary beds of
lungs where gas
exchange occurs
Pulmonary Circuit
Pulmonary
arteries
Aorta and branches
Venae
cavae
Right
atrium
Right
ventricle
Oxygen-rich,
CO2-poor blood
Oxygen-poor,
CO2-rich blood
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Pulmonary veins
Left
atrium
Heart
Left
ventricle
Systemic Circuit
Capillary beds of all
body tissues where
gas exchange occurs
Figure 18.4 The circular and spiral arrangement of cardiac muscle bundles in the myocardium of the heart.
Cardiac
muscle
bundles
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• HEART CHAMBERS
• 4 chambers
• Atrium (left/right
atria)
• divided by the INTERATRIAL
SEPTUM
• Function of Atria: receives blood
from veins
(pig heart)
• RIGHT ATRIA
• receives blood from superior &
inferior vena cava
• blood that’s been used
• oxygen poor – high in CO2
• LEFT ATRIA
• receives blood from
pulmonary veins
• coming from lungs
• rich in oxygen
• Ventricles
(left/right)
(pig heart)
• muscular pumps – divided by
INTERVENTRICULAR SEPTUM
• RIGHT VENTRICLE
• receives blood from the right atria (O 2
poor)
• pumps blood to the lungs through the
PULMONARY ARTERIES
• LEFT VENTRICLE
• receives blood (O2 rich) from the left
atrium
• pumps blood to the body through the
AORTA
Figure 18.10 Anatomical differences between the right and left ventricles.
Left
ventricle
Right
ventricle
Interventricular
septum
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• Systemic Circulation
• heart – lungs – heart –
body – heart
• HEART VALVES (4)
• allow for “one way” circulation
• 2 Atrioventricular
Valves (AV valves)
1. Tricuspid Valve: between right atria
and right ventricle
2. Bicuspid or Mitral Valve: between
left atria and left ventricle
• heavier & stronger of the two
Figure 18.6a Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Mitral
(left atrioventricular)
valve
Tricuspid
(right atrioventricular)
valve
Aortic valve
Pulmonary valve
Cardiac
skeleton
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Anterior
Figure 18.6b Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Mitral
(left atrioventricular)
valve
Tricuspid
(right atrioventricular)
valve
Aortic valve
Pulmonary valve
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Figure 18.6c Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Chordae tendineae attached
to tricuspid valve flap
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Papillary
muscle
Figure 18.6d Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Opening of inferior
vena cava
Tricuspid valve
Mitral valve
Chordae
tendineae
Myocardium
of right
ventricle
Interventricular
septum
Papillary
muscles
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Myocardium
of left ventricle
• CHORDAE TENDINAE and papillary
muscles stop valves from being folded
backwards
CHORDAE TENDINAE
3. Pulmonary Semilunar Valve: between the
pulmonary artery and right ventricle
4. Aortic Semilunar Valve: between aorta
and left ventricle
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Homeostatic Imbalance
• Two conditions severely weaken heart:
– Incompetent valve
• Blood backflows so heart repumps same blood
over and over
– Valvular stenosis
• Stiff flaps – constrict opening  heart must exert
more force to pump blood
• Valve replaced with mechanical, animal, or
cadaver valve
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Pathway of Blood Through the Heart
• Pulmonary circuit
– Right atrium  tricuspid valve  right
ventricle
– Right ventricle  pulmonary semilunar valve
 pulmonary trunk  pulmonary arteries 
lungs
– Lungs  pulmonary veins  left atrium
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Pathway of Blood Through the Heart
• Systemic circuit
– Left atrium  mitral valve  left ventricle
– Left ventricle  aortic semilunar valve 
aorta
– Aorta  systemic circulation
PLAY
Animation: Rotatable heart (sectioned)
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Coronary Circulation
• Functional blood supply to heart muscle
itself
– Delivered when heart relaxed
– Left ventricle receives most blood supply
• Arterial supply varies among individuals
• Contains many anastomoses (junctions)
– Provide additional routes for blood delivery
– Cannot compensate for coronary artery
occlusion
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Coronary Circulation: Arteries
• Arteries arise from base of aorta
• Left coronary artery branches  anterior
interventricular artery and circumflex artery
– Supplies interventricular septum, anterior ventricular
walls, left atrium, and posterior wall of left ventricle
• Right coronary artery branches  right
marginal artery and posterior interventricular
artery
– Supplies right atrium and most of right ventricle
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Figure 18.11a Coronary circulation.
Aorta
Pulmonary
trunk
Left atrium
Superior
vena cava
Anastomosis
(junction of
vessels)
Left
coronary
artery
Right
atrium
Right
coronary
artery
Right
ventricle
Right
marginal
artery
Circumflex
artery
Posterior
interventricular
artery
The major coronary arteries
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Left
ventricle
Anterior
interventricular
artery
Homeostatic Imbalances
• Angina pectoris
– Thoracic pain caused by fleeting deficiency in
blood delivery to myocardium
– Cells weakened
• Myocardial infarction (heart attack)
– Prolonged coronary blockage
– Areas of cell death repaired with
noncontractile scar tissue
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Microscopic Anatomy of Cardiac Muscle
• Cardiac muscle cells striated, short,
branched, fat, interconnected,
1 (perhaps 2) central nuclei
• Connective tissue matrix (endomysium)
connects to cardiac skeleton
– Contains numerous capillaries
• T tubules wide, less numerous; SR simpler
than in skeletal muscle
• Numerous large mitochondria (25–35% of
cell volume)
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Figure 18.12a Microscopic anatomy of cardiac muscle.
Nucleus
Intercalated
discs
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Cardiac
muscle cell
Gap junctions
Desmosomes
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 from cell to
cell; electrically couple adjacent cells
• Allows heart to be functional syncytium
– Behaves as single coordinated unit
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