Transcript Ch 20 – The Heart

Ch 20 – The Heart
Anatomy
I. Size- clenched fist
II. Location
A. in the mediastinumarea between the lungs
B. inside a sac named
the pericardium
1. pericardium has
layers
a. fibrous
b. parietal
c. visceral
-also forms the outer
layer of the heart called
epicardium
Anatomy
III. Description of heart
A. Hollow, muscular
• Outer layerepicardium
• Middle layermyocardium
• Inside layerendocardium
Anatomy
B. 4 chambered
1. Atria(um)- Top
a. Right- blood from the body cells via the
systemic system
- enters via vena cava
b. Left- blood from the lungs via the pulmonary
system
- enters via pulmonary veins
2. Ventricles -bottom
a. Right- blood exits to the lungs
- via pulmonary arteries
b. Left- blood exits to all other body parts
- so there is a thick muscular wall
- exits heart via aorta
C. Summary-human heart is a double pump
having two separated sides
•
1. Right receives deoxygenated blood
and sends it to the lungs.
•
2. Left receives oxygenated blood and
sends it to the body.
Anatomy
D. Evidence of Walls
1. External
a. Coronary sulcus- fills
with fat
2. Internal= septa
a. Interatrial- thin muscle
• Fossa ovalis- hole that
shows connection of
atria in fetus
b. Interventricular- thick
muscle
Anatomy
F. Valves- connect chambers
1. Atrioventricular valves;
a. Right= tricuspid valve
b. Left-= Mitral valve
(bicuspid)
2. Opening and closing –
a. controlled by papillary muscles on
ventricular walls
b. Attach to cusps of valves via chordae
tendineae (heart strings)
c. make “lub” sound when closing
G. Valves –connect to bl.v leading out of
heart
-make “dub” sound when closing
1. pulmonary (semilunar) valve- between
right ventricle and pulmonary artery
2. aortic (semilunar) valve -between left
ventricle and aorta
-Color Plate # 49, and 50
IV. Coronary Circulation
A. Coronary Arteriesbranch off aorta and
take oxygenated bl. to
heart tissue
1. corona = crown
2. right and left
coronary arteries
IV. Coronary Circulation
3. Clinical considerations
a. ischemia- reduced coronary
circulation due to plaque,
can lead to…
b. angina- pain in chest
c. thrombosis- clot
Treated w/- catheters, angioplasty, CABG
See page 667-668 and discuss.
IV. Coronary Circulation
B. Cardiac Veins- return deoxygenated bl.
collected in heart tissue via great cardiac
vein to coronary sinus
1. Sinus
a. on posterior side
b. between right atrium and vena cava
C. Color plate #52
V. Heartbeat
A. Involves 2 cell types
1. Contractile Cells
a. propel bl.
b. 99% of heart
c. respond to action potential
d. invol.
e. striated (z lines)
f. branched w/ intercalated discs
g. all together act like 1 giant cell called
synctium
2. Specialized Cells of Conducting System
1. control and coordinate contractile
cells
VI. Cardiac ConductionA. heart beats out of body!
Intrinsic- has its own system of stimulating
muscle cells
1.Sinoatrial node- SA node
a. called pacemaker
b. initiates the heart beat
c. in rt. atrial muscle
2.Internodal Fiber bundles
a. carries impulse to next node thru
conduction cells in atria
VI. Cardiac Conduction3.Atrioventricular Node
a. located b/t/w rt. atrium & ventricle
b. impulse delays here(due to smaller diameter)
to give atria time to completely contract
4. Atrioventricular bundle
a.also called Bundle of His
b. carries impulse to ventricular muscle walls
via. Interventricular septum
c. @ bottom impulse branches out
5. Purkinje Fibers
a. spread impulse through ventricle
b. cause muscle cells to contact
*See plate 51
Sequence the following parts of
the conduction system from
impulse generation to
ventricular contraction
AV node, perkinje fibers, internodal tracts,
interventricular fibers, SA node
VII. Cardiac Cycle
A. Repeated contractions
B. 2 main parts
1. Systole- contraction
a. bl. pushed out of chamber
b. top # in B.P.
2. Diastole- relaxation
a. bl. fills chamber
b. bottom # in B.P.
VIII. Impulse Conduction
• A. measured w/ electrocardiograph
1. reading is electrocardiogram
•
ECG or EKG
•
2. see plate 51
•
3. x axis= time
•
Y axis= depolarization
• B. Basic Features
•
1. P wave- depolarization of atria
•
2. QRS complex- depolarization of ventricle
•
3. T wave- repolarization of ventricles
• C. Other features
•
1. QT interval- vent. Contraction + relaxation
+atria relax
•
2. ST interval- time to repolarize ventricles
• D. Arthymias- abnormal cardiac activity
1. bradycardia- slow
•
2. tachycardia- fast
- Due to
•
a. damage to myocardium
•
b. pacemaker damage
•
c. drugs
•
d. electrolyte imbalance
IX. Calculating Cardiac output
• A. Cardiac OutputVol. of bl. pumped from heart in one
min
• B. Stroke VolumeAmt of bl. fr. 1 ventricle in 1 heart beat
• C. Calculate Cardiac Output
Stroke vol. X beats/min=C.O.