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Chapter 19 - Cardiovascular System: The Heart
intensity
a
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apex of heart rests on diaphragm - -
et. Znexinum
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روزمره مردم داریم
heartwall
posterior inne
I. Heart Anatomy A. General
1. size - about the size of your fist; weighs less than 1 lb. 2, location
a. anterior to vertebral column b. posterior to sternum c. flanked laterally by lungs
d. tips slightly to left -oblo 20 B. coverings
1. enclosed by double sac of serous membrane - pericardium
een Garietal layer a. parietat pericardium - 2 layers: fibrous and serous - de
b. visceral pericardium (epicardium) tough Super i eule in 1 to 2. pericardial cavity meal white lepote it's anchors hea
ace tonvict/ a. space between epicandines and serons layer of parietal pericardium b. serous fluid
visceral C. heart wall - 3 layers
1. epicardium 2. myocardium - bulk of heart - layer that actually contracts
3. endocardium - endothelial membrane that lines interior of heart + Code D. chambers = 4.
. filnous skeleton of valves 1. components, Lleyt
a. 2 atria ut.
-superior -receive blood
-small thin-walled b. 2 ventricles ut. +
-inferior -pump blood -on inner walls: trabeculae carnae
papillary muscles -right ventricle
-forms most of anterior surface of heart
-pumps blood into pulmonary trunk and into lungs -left ventricle
-forms heart apex dominates
-pumps blood into aortaestudi
c. associated structures swich - ) -interatrial/interventricular septum - divides heart longitudinally nu E. Great vessels associated with chambers
1. superior/inferior vena cava
a. superior vena cava - returns blood from body areas superior to heartit.
b. inferior vena cava - returns blood from body areas below heart (aut.) 2. coronary sinus - collects blood draining from myocardium itself
3. 4 pulmonary veins- enter left atrium -carries blood from lungs to heart F. Pathway of blood through heart e 1. pulmonary circuit
> a. collects blood returning to heart from body lungs for oxygenation
b. right side of heart
nae inregular muscle tolds- sone
name depends
on which Chamber it
pulmonary trunk pourt. 14tarteries - carta pump blood to
lunges
CA
blood ejects
Att24
blood from left
ventricle to
all body
short route
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Strictly series as ans
I function
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long moute- supplied be entire body in oxu gerente de 25
lots of pressure
Between
ventricle
also helps hold
cu sps Closed
Wet. blood is 0, poor/CO.rich
enters right atrium-right ventricle---pulmonary trunk -->lungs->
pulmonary veins - left atrium systemic circuit
-left side of heart issure -blood O., rich/CO, poor
-leaves lungs-> Pulmonary veins left atrium -> left ventricle-> aorta->
all parts of body -> veins --> superior/inferior vena cava-->right atrium
-walls of left ventricle twice as thick as right one H. Heart valves
3x -blood flows in one direction: atria ventricles-> arteries -enforced by presence of 4 valves: paired atrioventricular and semilunar valves 1. atrioventricular (av) valves
a. prevents backflow of blood into atria when ventricles contract b. right av valve - tricuspid valve - 3 flaps c. left av valve - bicuspid valve (mitral valve) - 2 flaps d. chordae tendineae
-collagen cords
-anchor cusps to papillary muscles e. heart relaxed - av valves hang down into ventricular chamber f. blood flows from atria into ventricles
-Ventricles contract
-blood forced up against valve flaps closing them 2. two semilunar valves
a. between ventricles and arteries b. prevent backflow of blood into ventricles when ventricles relax c. aortic semilunar valve - between left ventricle and aorta d. pulmonary semilunar valve - between right ventricle and pulmonary trunk
e. ventricles contract forcing open semilunar valves, close when ventricles relax eardiac circulation 1. right and left coronary arteries
a. provide functional blood supply of heart b. branch from root of aorta c. left coronary artery divides into anterior interventricular artery and circumflex artery
d. right coronary artery divides into marginal artery and posterior interventricular artery 2. cardiac veins and coronary sinus
a. cardiac veins collect venous blood
b. cardiac veins join to form coronary sinus empties to right atrium 3. disorders
a. angina pectoris
-deficient blood flow to heart -weakens cells, but they don't die myocardial infarction -cells die - infarct
- areas and aut non conspects -heart attack - Euro mong
prolonged
Coronary,
blockage
they don't die adult candiae
mutch is amitotic-
- areas of cell death dependsch repaired af nonconfractice canape
sean tissue effects location efficienen of heart
7 damage
(leftcentricle being more serious)
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domosomes recent
separation of adjacent cells
during contraction I gap junctions allow ons
سے ات مهر 45 ه م ش
mitting the electrices
transmitting the ampulses
membrane
nesting
i
filament
ction - sane sliding
mechanismi
Prateaves-depolarization
2) wave goes down Ttubules
2.) cat binds cultrosporing
II. Heart Physiology
A Properties of cardiac muscle
1. microscopic anatomy
a. striated b. short/fat c. branched d. interconnected by intercalated discs a
-contain desmosomes and gap junctions
-heart works as 1 unit due to gap junctions) gap e. 1-2 large nuclei f. lct matrix - endomysium with lots of capillaries g. matrix connected to dense fct skeleton
-collagen and elastin fibers - link cardiac cells together h. lots of mitochondria 2. energy requirements
a. continual supply of 0.2 for energy metabolism b. relies mostly on aerobic respiration
-a decrease in O, not well tolerated
ses fatty acids most effectively for ATPR 3. mechanism and events of contraction
a. mostly same as skeletal muscle contraction b. differences
-all or none response at organ level - not cellular -can be self-excited with rhythm
-refractory pd. longer - prevents tetanic contraction (heart would stop) B. conduction system of heart - intrinsic
1. components SEE a. sa node - pacemaker (Sino a
b. av node catrioventricular c. av bundle (H;'s bundle) pinterwentniealen sentum
ulse? d. right/left bundle branches e. Purkinje fibers - penetrate into ventricular myocardi SA node a. small mass located in right atrial wall' AL b. depolarizes 70/80 times /minute c. initiates each depolarization wave - moves across heart - sets pace - sinus rhythm
d. depolarization travels to av node - then to all branches and fibers 3. ans (extrinsic) (autonomic nervous sy seu
-speeds up/slows down rate
-sympathetic (1) vs. parasympathetic (1) Chormon 4. defects
a. arrhythmias - irregular heartbeat
b. fibrillation - out of phase contractions - Ma r et circular in dies I was acc. heart block-impaired transmission of impulses from atrium to ventricles (avnede
C. electrocardiography
1. ECG - electrocardiogram - graphic recording of electrical changes during heart activity
de blar122 Hon 2. 3 distinct waves - deflection waves:
a. P wave - impulse from sa node to atria
catrica, contraction-systole Sustele b. ORS complex - ventricles contract (ventricular desdari zat, on necueca
Sostel C. T wave - ventricles repolarize - U ticles relay
3. P to R - from atrial excitation to ventricular excitation
nedes- specializeel
Mie
I
nervelike, non contractile
• Sexton Cardiae calls that
he initiate & distribute
impulses thrownout myocar
heart iheart
del sequential manner from but beatSAS
drum, deplanires contracts
suotum-caune verrichten
characteristic
all
rhyther reled
Acer
contractions - mass of writhing Womens -
reataici medley on Spopun
Necc grasemakacs
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usually & describede ventricular
events
heart totally elated-
quiesceat pd.
ventricular ejection phase
c
me 4. Oto T - from ventricular depolarization to repolarization cuenta E 5. size, duration, and timing of waves - consistent; change in waves - problems
D. cardiac cycle
1. terms
a. systole - contraction pd. (atria and ventricles) b. diastole - relaxation pd. (atria and ventricles) C. cardiac cycle - events occurring during 1 heartbeat
-marked by succession of pressure and blood volume changes within the heart
-each ventricle pumps same volume of blood per heartbeat 2. route of blood
a. pd. of ventricular filling: mid-to-late diastole
-blood flows into atria and ventricles -av valves open -sl valves shut -atria contract - atrial pressure increases -residual blood in atria propelled into ventricles
-atria relax - diastole b. ventricular systole
-atria in diastole -ventricles begin contracting -pressure rises sharply -av valves close -for split second ventricles completely closed - blood volume constant -sl valves open due to more pressure in ventricles than in arteries -blood forced into aorta and pulmonary trunk isovolumetric relaxation: early diastole -ventricles begin to relax -ventricular pressure decreases -sl valves close due to blood pressure decreasing in ventricles causing backflow of
blood (in arteries) towards heart -ventricles once again closed chambers - for split second -miscellaneous
-atria still in diastole -atria filling with blood – therefore pressure on rise in atria -av valves forced open -ventricles begin filling -atrial pressure drops/ventricular pressure rises - completing cycle -flow of blood controlled by pressure changes
-blood flows along a pressure gradient - from higher to lower D. E. Heart sounds
1. normal t a: lub-dup V
b. closing of the valves systole Lub c. 18 sound - av valve close
bile Dup d. 2nd sound - sl valve close 6
2. abnormal
-murmurs
-most often indicates valve problems F. Cardiac output (m/min
1. amt. of blood pumped out by each ventricle per minute CO 2. product of heart rate (hr) and stroke volume (sv)
beats per minute mi/beat
Be influenced by co
peripheral
res.sltumee
blood volume
:
mitral then tricuspid
aortie sh' then palchowary SL
close
25 heats (minute
rom! (beat
roblem - swishing noise
Colml/min) = HR x sr
Co=5250 ml/min.
Beat
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3. stroke volume - volume of blood pumped out by a ventricle with each contraction 4. regulation of heart rate
a. autonomic nervous system regulation by cardiac centers in medulla oblongata
-sympathetic (1) vs. parasympathetic (1)
-predominant influence over heart rate is inhibitory b. chemical regulation
-hormones
-epinephrine
-thyroxine V -ions - Ca+, Na+ , K (electrolyte balance important - if off, can be fatal - heart stops)
C. physical factors: age, gender, exercise, body temperature IV. Aging aspects of heart
temes g. faster A. sclerosis and thickening of heart flaps be
1 - fash LLLIUNCILIIB OLLCAIL laps Add B. decline in cardiac reserve C. fibrosis of cardiac muscle -- arrhythmias D. Atherosclerosis - begins in childhood luck
-smoking -stress
-couch potato / C#-diet - single most important contributor to cardiovascular disease antenne
els in
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O
exeneise - faste
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Fr 7
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of anteny handening beginnings - to cardiovascular disease arxenosclers, s
7 AUKAS
pushits
Co Ou boue
C
levels
all accelerate process
systole (contraction) diastile (relor)
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ECG (EKG)
actrical impulse
electricelin
ventricles
o
seat from sa node to atas atrice dypolerire Connect
Trepi
repolarize the lay-
diastole
Systole
ventrieles depolarize t contract. systole
Q-7-beginning 8
yeargimetall Katrice
eadlarization to
regolarization
P-Q interval beginning of atrial
excitation to beginning of
veutaicela excitation Aro interval - includes atrial depolarization
(comentario e os ante con using 7 impulse S-T entine vintricle myocardium depolaridwal
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