Heart - Lecture 16
Anatomy & Physiology 220 with Tomco at Brigham Young University
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heart
functions as pump
mediates between the systemic and pulmonary circuit
atria
top receiving chambers
ventricles
bottom pumping chambers
pulmonary circuit
vessels that carry blood to and from lungs
right atria and ventricle
systemic circuit
vessels that carry blood to and from body tissues
left atria and ventricle
base
posterior and superior surface of heart
apex
anterior and inferior and points to left hip
fibrous pericardium
attached to diaphragm
pericardial cavity
space between parietal and visceral layers
contains serous fluid
pericardium
functions:
prevents undesired movement, overfilling of heart, reduces friction
pericarditis
inflammation of pericardium
epicardium
visceral pericardium; most superficial layer
myocardium
forms bulk of heart
cardiac muscle
deep to epicardium
infarctions occur here in this layer
endocardium
lines heart chambers
covers valves
deepest layers
fibrous skeleton
functions:
separates atria and ventricle
anchors heart valves
provides electrical insulation between atria and ventricles
provides framework for attachment of cardiac muscle tissue
right atrium
receiving chamber for oxygen poor blood from systemic circuit
right ventricle
pump of the pulmonary circuit
left atrium
posterior surface of heart
receives oxygen rich blood from lungs
left ventricle
most muscular of chambers (3x thicker than right ventricle)
forms apex and inferior surface of heart
pump of systemic circuit
aortic semilunar valve
valves
can be cuspid/semilunar
composed of dense connective tissue
permits passage of blood
prevents backflow of blood
cardiac muscle tissue
fibers are short, branched, striated, and contain 1-2 nuclei
joined by intercalated discs (gap junctions; desmosomes)
more mitochondria and ATP than skeletal muscle
cardiac cycle
period of time from start of one heartbeat to initiation of next
all chambers experience alternate periods of contraction and relaxation
systole
contraction of a heart chamber
diastole
relaxation phase of a heart chamber
conducting system
specialized cardiac muscle cells that carry impulses throughout the heart musculature
steps of conducting system
1. sinoatrial node - sets rate for heart to beat
2. atrioventricular node - slows conduction of impulse as it travels from a/v
3. AV bundle - conduct impulse into in/ven septum
4. r/l bundle branches - impulse goes to apex
5. purkinje - heart contracts
coronary plexus
sympathetic and parasympathetic innervation
sympathetic innervation
T1-T5
increases rate and force of heart contraction
parasympathetic
medulla oblongata and vagus nerve X
decreases rate of heart contraction
heart failure
progressive weakening of heart
weak ventricles, failure of ventricles to empty completely, overfilling, congestive heart failure
congestive heart failure
heart enlarges greatly, pumping efficiency progressively declines, pulmonary edema
cause unknown
Myocardial infarction
caused by blockage of coronary artery
lack of blood flow to a region of myocardium causes heart muscle to die (due to oxygen deprivation)
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