Chapter 20 Cardiac
Ventricles
two inferior DISCHARGING chambers
eject blood into arteries
ventricles
two RECEIVING chambers of heart
Atria
receive blood from veins that return blood to the heart
Atria
Intercalated disc
tranverse thickening of sarcolemma that connect the ends of cardiac cells together
Contains desomomes and a Gap Junction
Intercalated Disc
Demosomes
holds fibers together
Gap Junction
allow action potential to flow from one muscle fiber to neighboring cellls so the all contract at the same time called FUNCTIONAL SYNCTIUM
prevents prolaspe of AV valves on systole (ventricular contraction)
cordae tendinease/papillary muscle
heart strings
cordae tendinease
tendons that are attached to the triscuspid valve which are attached to papillary muscles
chordae tendinease
receives blood from superior and inferior vena cava and the coronary sinus
R Atrium
Coronary Sulcus
lies deep and encircles most of the heart
marks the division between the artria and ventricles
coronary sulcus
Auricle
protrudes off each atriym anteriorly
purpose to increase the capacity of the atrium and to increase the volume of blood it contains
Auricle
Oxygenate Blood
L Ventricle
Right and Left arteries
supply the myocardium w/blood
Deoxygenated Blood
R ventricle
Pericardium
membrane that surrounds and protects the heart
Fibrous Pericardium
superficial, composed of inelastic, dense, irregular connective tissue
prevents overstretching of the heart, provides protection and anchors the heart to the mediastinum
fibrous pericardium
facilitates the movement of blood
Fibrous pericardium
Serous pericardium
depper, thinner membrane that forms a double layer around the heart
Outer membrane (serous pericardium)
parietal; attache to the fibrous pericardium
Inner layer (serous pericardium)
visceral; one of the heart wall layers and is infused to the heart surface
"epicardium"
inner layer of serous prericardium (visceral)
Pericardial Cavity
small space between the parietal and visceral layers of the serous pericardium
pericardial fluid
inside of pericardial cavity; lubricating serous fluid
reduces friction between layers as heart moves
pericardial fluid
Heart Location
in the mediastinum on the superior surface of diaphragm
Epicardium (heart layer)
external layer
contains an outer layer and inner layer
Epicardium
provides smooth, slippery covering to the outside of heart
epicardium
Myocardium (heart layer)
composed of cardiac muscle
consumes the most energy
Myocardium
responsible for pumping action of heart
Myocardium (heart layer)
Edocardium (heart layer )
simple, squamous epithelium
"endothelium"
Edocardium (heart layer)
provides a smooth lining for the heart chambers and covers heart valves
Endocardium
decreases function when blood flows through the heart
Endocardium
Right Ventricle
receives blood from the right atrium thru the triscupsid valve; anterior surface of heart
Pulmonary Trunk
located in right ventricle
large artery that receives blood from pulmonary valve and then splits into the right and left pulmoary arteries which conveys blood to lungs
Pulmonary Trunk
Left Atrium
forms most of the base of heart
receives blood from the lungs through four pulmonary veinsq
left atrium
Ligamentum Arteriosum
temp vessel of fetus that shunts blood from pulmonary trunk into aorta
thickest chamber of heart
Left ventricle
contains biscuspid valve, aortic valve, right and left coronary arteries
Left ventricle
Right and Left coronary arteries
receives blood from the aorta that supply the myocardium
trabeculae carneae
increases contractility and stroke work
ridges formed by cardiac muscles bundles
trabeculae carneae
Interventricular septum
separates the right and left ventricle
Bicuspid (Mitral) valve
blood passes through this valve into the left ventricle
prevents back flow from left ventricle to the left atrium
Bicuspid (Mitral) valve
found in the left atrium
Bicuspid (Mitral) valve
Triscupid valve
prevents back flow from the right ventricle to the right atrium
located in right atrium
Tricuspid Valve
Aortic Semilunar Valve
prevents back flow from aorta to the left ventricle
Pulmonary Valve
prevents back flow of blood from pulmonary trunk to right ventricle
cardivascular center
nervous system regulation of the heart
located in the medulla center
cardiovascular center
cardioaccelerator/cardiohibitory center
cardiovascular center
Sinoatrial node (SA)
in right atrial wall
where cardiac excitation begins
Sinotrial node (SA)
spontaneous deplorization of SA node
pacemaker potential
spontaneous deplorization of SA nde and when thresholds is reached, action potential is initiated
pacemaker potential
natural pacemaker
sets the rhytm for heart contraction
period of maintained deplorization
plateau
partially due to opening of voltage-gated slow Ca++ channels (Ca++ inflow balances the K+ outflow)
plateau
P wave
signifies depolarization of SA node
QRS complex
signifies ventricular depolarization
T wave
signifies ventricular repolarization
Korotkoff sounds
fist sound occurs as AV valve closes and signifies beginning of ventricular systole, second sound occurs when SL valve close at the beginning of ventricular diastole
Stroke volume
amount of blood pumped out of the ventricle on beat
volume of blood ejected from the left or right ventriclr into aorta or pulmonary trunk each minute
cardiac output
CO(ml/min)=SV(ml/beat) x HR (beats/min)
Cardiac Output
Frank-Starling Law of the Heart
the more the heart muscle is stretched(filled) before contraction (during diastole) the more forcefully the heart will contract during systole
"preload is proportional to end diastolic volume"
Frank-Starling Law of the heart
Aortic Valve
blood passes thru it to the ascending aorta
located in Left ventricle
Aortic Valve
SNS (reg of the heart)
norepinephrine binds to beta 1; speeds deplorization in SA and AV node fibers; enhances Ca+ entry which increases contractility
Parasympathetic Nervous System (heart regulation)
reaches heart thru vagus nerve; vagal axon release acetycheline which decrease HR by slowing spontaneous depolarization in autorhythmic fibers
Hormones (reg of heart)
epineprine, norepinephrine, and thyroid hormone increase HR and contractility
Cations (reg of heart)
excess Na+ ions block Ca+ in flow resulting in decrease in HR and contration; exccess K+ blocks generation of action potential
Age
fetus has fastester HR, decreases with age
Exercise (reg of heart)
increase HR, trained athletes can have a slow HR
Body temp
heart rate increase with increased body temp
CHF
inability of the heart to provide specific pump actions to maintain blood flow to meet the needs of body
CAD
accumulation of athersclerotic plagues in coronary arteries
Myocardial infarction
complete obstruction of coronary
Autorhythmic
self excitable
Conduction system
route for propogating action potentials through heart muscles
1. sinoatrial (SA) node 2. AV node 3. Bundle of his 4. Bundle branches 5. Purkinje fibers
the conduction system
Afterload
higher ventricular pressure pushes the semilunar valves open and the pressure that must be overcame to open the valves
an increase in afterload causes a decrease in...
stroke volume
Systole
period of contraction
Diastole
period of relaxation
can damage heart
HTN and atherosclerosis can cause an increase in afterload
Atrial systole
atria are contracting, ventricles are relaxed
forces blood thru the open AV valves into the ventricles
Atrial systole
atrial systole
the end is also the end of ventricular diastole
QRS complex
beginning of ventricular depolarization
ventricular systole
ventricles are contracting, atria are relaxed
the pressure rises in the ventricles pushing blood against the AV valves CLOSING them
ventricular systole
End-systolic volume
remaining blood volume (about 60ml)
T wave
beginning of ventricular repolarization
Stroke volume
volume ejected per beat by each ventricle and is equal to the end diastoliv volume minus end-systolic volume
Pulmonary Circulation
sends deoxgenated blood from the right ventricle to the lungs and oxygenated blood back to left atrium