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Cardiovascular System
Consists of the heart and blood vessels. The heart pumps
blood through vessels and deliver the blood to all the body's
organs and then return it to the heart. The broader term,
circulatory system includes the blood.
TERM 2
Pulmonary Circuit
DEFINITION 2
Carrier blood to the lungs for gas exchange and returns it to
the heart. The right side of the heart supplies the pulmonary
circuit. It receives blood that has circulated through the body,
unloaded its O2 and nutrients and picked up co2 and other
wastes.
TERM 3
Pulmonary Circuit (II)
DEFINITION 3
It pumps the O2 poor blood into large artery (pulmonary
trunk) which divides it into right/left pumonary arteries.
These transport blood to the air sacs (aveoli) of the lungs,
where CO2 is unloaded and O2 is picked up. The O2rich blood
flows by the way of the pulmonary veins to the left side of the
heart. RIGHT SIDE: CO2 Rich blood, O2 Poor blood
TERM 4
Systemic Circuit (II)
DEFINITION 4 After circulating through the body, the now deoxygenated systemic blood returns to the right side of the heart through 2 veins: superior vena cava (draining the upper body) and inferior vena cava (draining everything below the diaphram). The major arteries and veins entering and leving the heart are called great vessels (great arteries and veins) b.c. of their large diameters. TERM 5
Sytemic Circuit
DEFINITION 5 Supplied blood to every organ of the body, including other parts of the lungs and the wall of the heart itself. The left side supplied the systematic circuit. Blood leaves its way by the aorta which takes a sharp inverted U (aortic arch) and passes down, posterior to the heart. It gives off arteries that supply the head, neck , and upper limbs. Then it travels through the thoracic and adominal cavities and issues smaller arteries to the other organs before branching into lower limbs. LEFT SIDE: O2 Rich, CO2 Poor blood
Heart
Located in the throacic cavity in the mediastinum, bt. lungs
and deep to the sternum. Tilted towards the left. The broad
superior portion is the base, which is the point of attatchment
for the great vessels. The inferior end tapers to a blunt point,
the apex, immediately above the diaphram. Size of one's fist.
TERM 7
Pericardium
DEFINITION 7 Double-walled sac in which the heart is enclosed. The outer wall, is the pericardial sac (parietal pericardium) which has a touch superficial fibrous layer of dense irregular connective tissue and a thin deep serous layer. The serous layer turns inward at the base of the heart and forms the visceral pericardium (epicardium) as part of the heart wall. The sac is held by ligaments to the diaphram and firbous c.tissue. The peri isolates the heart from other thoracic organs and allows it room to expand, yet resist excessive expansion. TERM 8
Pericardium (II)
DEFINITION 8 B.t. parietal and visceral membranes is a space called pericardial cavity which containspericardial fluid (by pericardiac sac) inside borth layers to prevent layers from rubbing together and cushioning for heart when it expands. In pericarditis, inflammation of the pericardium, the membranes become roughened and produce painful friction rub with each heartbeat. TERM 9
Epicardium
DEFINITION 9
Serous membrane of the external heart surface made up of
simple squamous epithelium overlying a think layer of
areolar tissue. In some places it is thick layer of adipose
tissue while in other areas it is fat-free and translucent.. The
largest branches of the coronary blood vessels travel through
the epicardium.
TERM 10
Endocardium
DEFINITION 10
Lines the anterior of the heart chambers made up of simple
squamous epithelium overlying a thin areolar tissue layer,
but has NO adipose tissue. It also covers the valve surfaces
and is continous w/ the endothelium of the blood vessels.
Sulci
Grooves that mark the boundaries of the 4 chambers. They are largely filled by fat and the coronoary vessels. 1coronary (atrioventricular) sulcus encircles the heart near the base and separates the atria above from the ventricles below. 2Anterior interventricular sulcus dive 2 ventricles and 3Posterior interventricular sulcus overlie the interventricular septum (wall) that divides the r+l ventricles. TERM 17
Interatrial septum & Interventricular
septum
DEFINITION 17 Wall that seperates R+L atria. 2) more muscular, vertical wall b.t. ventricles. The right ventricle pumps blood only to the lungs and back to the left atrium, so its wall is moderately muscular. The wall of the left ventricle is 2-4 times as thick b.c. it bears the greatest workloads of all 4 chambers pumping blood trhough the entire body. Both ventricles exhibit internal ridges called trabeculae carnea. TERM 18
Valves
DEFINITION 18
There is a valve bt. each atrium and its ventricle and another
at the exit from each ventricle into its great artery but the
heart has NO valves where the great veins empty into the
atria. Each valve consists of 2 or 3 fibrous flaps of tissue
called cusps or leaflets, covered w/ endocardium.
TERM 19
Valves (II)
DEFINITION 19 Atrioventricular (AV) valves regulate the openings bt. the atria and ventricles. The right AV (tricuspid) valve has 3 cusps and the left AV (bicuspid) has 2. The left AV valve is aka the mitrial valve since it resembles a miter, pope hat. Stringy tendinous cords (chordae tendianea) resemble the shroud lines of a parachute, connect the valve cusps to conical papillary muscles on the floor of the ventricle. They prevent the AV valves from flipping inside out or bulging into the atria when the ventricles contract. TERM 20
Valves (III)
DEFINITION 20 The semilunar valves (pulmonary and aortic valves) regulate the flow of blood from the ventricles into the great arteries. The pulm.valve controls the opneing from the right ventricle into the pulmonary trunk, and the aortic valve controls the opening from the left ventricle into the aorta. Each has 3 cusps. These valves have no tendinous chords. They dont open and close by any muscular effort of their own. The cusps are pushed open&closed by changes in blood pressure that occur as the heart chambers contract and relax.
Coronary Circulation
Coronary circulation is the circulation of blood in the
blood vessels of the heart muscle (myocardium).
The vessels that deliver oxygen-rich blood to the myocardium
are known as coronary arteries. The vessels that remove the
deoxygenated blood from the heart muscle are known as
cardiac veins.
TERM 22
Left Coronary Artery (anterior interventricular
branch)
DEFINITION 22 Travels through the coronay sulcus under the left auricle and divides into 2 branches: 1Anterior interventricular branch - travels down the to the apex,and joins the posterior interventricular branch. AKA left anterior descending (LAD) branch. It supplies blood to both ventricles and the anterior 2/3 of the interventricuar septum. AKA widow maker b.c if the artery gets abruptly and completely occluded it will cause a massive heart attack that will lead to death. TERM 23
Left Coronary Artery (circumflex branch)
DEFINITION 23
2 circumflex branch -cont. around the left side of the heart
in the coronary sulcus. Give oss a left marginal branch that
gives blood to the left ventricle. It provides blood to the left
atrium and posterior wall of the left ventricle.
TERM 24
Right Coronary Artery (right marginal branch)
DEFINITION 24 Supplies the right atrium and sinoatrial node (pacemaker) cont. long the coronary sulcus and under the right auricle and gives off two branches: 1Right Marginal Branc - runs toward the apex of the heart and supplies to the lateral aspect of the right atrium and ventricle. It cnt. aruond the right margin of the heart to the posterior side and sends small branch to the atrioventricular node and then gives off a large posterior interv. branch (next slide) TERM 25
Right Coronary Artery (posterior
interventricular branch)
DEFINITION 25
This branch travels down the corresponding sulcus and
supplies the posterior walls of both ventricles as well as the
posterior walls of both ventricles as well as the posterior
portion of the interventricular septum. it ends by joining the
anterior interventricular branch of the LCA.
Cardiac Conduction System (steps 1-3)
1Sinoatrial (SA) Node- patch of the modified cariocytes in the right atrium, under the epicardium near the superior vena cava. This is the pacemaker that initiates each heartbeat and determines heart rate. 2.Signals from the SA onde spread throughout the atria. 3.The atrioventricular (AV) Node is fires. This node acts as an electrical gateway to the ventricles. The fibrous skeleton acts s an insulator to prevent currents from getting to the ventricles by any other route. TERM 32
Cardiac Conduction System (steps 4-5)
DEFINITION 32
- The AV bundle or bundle of His is the pathway by which signals leave the AV node. The bundle forks into right and left bundle branches which enter the interventricular septum and descend toward the apex. 5)Purkinje fibers are nervelike processes that arise from the lower end of the bundle branches and turn upward to spread throughout the ventricular myocardium. The fibers distribute the electrical excitation to the cardiocytes of the ventricles. TERM 33
Pacemakers
DEFINITION 33
Used for people who have heart problems that cause their
heart to beat too slowly Caused by a slow heartbeat are
sinus node disease and heart block. It's an artificial device for
stimulating the heart muscle and regulating its contractions.
TERM 34
Defibrillators
DEFINITION 34
An electrical device that provides a shock to the heart when
there is life-threating arrhythmia (irregular heartbeat)
present or stopped. Larger than pacemaker
TERM 35
Systole/Diastole
DEFINITION 35
Contraction of the heart. Relaxation of the heart.
Sinus Rhythm
The normal heartbeat triggered by the SA node. 70-80times
p/min (60-100bpm). Premature vetricular contraction (PVC)
or extrasystole: stimuli like caffeine causes other parts of the
conducion system to fire before the SA node does, setting an
extra heartbeat.
TERM 37
Ectopic Focus
DEFINITION 37
Any region of spontaneous firing other than the SA node. If
SA node is damaged, an ectopic focus will take over. The
most common is the AV node whch provides a nodal rhythm.
If neither AC or SA node work, other ectopic foci fire rates
from 20-40bpm. But the nodal rhythm is too little flow of
blood to brain, which calls for an artificial pacemaker.
TERM 38
Arrhythmia
DEFINITION 38
Abnormal cardiac rhythm, Ine cause of this is a heart block-
the failure of any part of the cardiac conduction system to
transmit signals, usually as a result of disease and
degeneration of conduction system fibers. Damaged to the
AV node causes total heart block causing the ventricles to
beat at their own rhythm.
TERM 39
Pacemaker Physiology
DEFINITION 39
The SA node fires spontaneously at regular intervals. It
doesn't have a stable resting membrane potential. It starts at
about -60mV and dirfts upward showing a gradual
depolarization called the pacemaker potential. This results
from a slow inflow of Na+ w/o compensating outflow of K+.
TERM 40
P.P. (2)
DEFINITION 40 When the pacemaker potential reaches a threshold of -40mV, voltage fates calcium channels open and Ca+ flows in from the extracellular fluid. This produces the rising (depolarizing) phase of the action potential (slightly 0mV).At this point, K+ channels open and K+ leaves the cell. This makes the cystol increasignly negative and creates the falling (repolarization) phase of the action potential.
Cardiac Cycle
consists of one complete contraction and relaxation of all
four chambers of the heart.
TERM 47
Fluid is governed by 1Pressure, 2Resistance
DEFINITION 47
1.Impels a fluid to move 2.Opposes flow.
TERM 48
Pressure
DEFINITION 48
Measured by a manometer. Expressed in mm Hg. Blood
pressure is measured with a ashygmomanometer
TERM 49
Pressure Gradients
DEFINITION 49
Different between more pressure at one point than another.
Fluids always flow down their pressure gradients, from the
high pressure point to the low pressure point. PRESSURE IS
INVERSELY PROPRTIONAL TO VOLUME. In heart, it is between
atria and ventricles
TERM 50
Pressure Gradients and Flow
DEFINITION 50 Pulling the syringe will increase volume, decrease pressure and pressure inside syrringe is lower than outside, the pressure gradient caues air to flow inward until te pressures are equal (filling of an expanding heart chamber). Pusing the syringe will decreased volume, increase pressure, air flows out until the pressures are equal (ejection of blood from a contracting heart chamber) In both cases, fluids flow down their pressure gradients.
Valves and pressure
They are just soft flaps of connective tissue with no muscle.
THey dont exert any effort of their own but are opened and
closed by the changes in blood pressure on the upstream and
downstream sides of the valves. Look at pg 736 picture (or
on PP)
TERM 52
Valvular Stenosis
DEFINITION 52
Valves aren't working properly
TERM 53
Cardiac Cycle Phase 1
DEFINITION 53
Ventricular filling:
TERM 54
Cardiac Cycle Phase 2
DEFINITION 54 Iso(same)volumetric contraction: Atria repolarize, relax and remain in diastole of rest of cardiac cycle. Ventricles depolarize, generate QRS complex, and begin to contract. Pressue in the ventricles rises and reverses the pressure gradient bt. atria and ventricles. The AV vavles close up. Even tho the ventricles contract, they don't eject blood yet and there is no change in volume. Ths is bc. pressure in the aorta and pulmonary trunk are gerater than pressures in the respective ventricles and they opposed the opening of the semilunar valves. The cardiocytes exert force, but with all 4 valves closed, the blood cannot go anywhere. TERM 55
Cardiac Cycle Phase 3
DEFINITION 55
Ventricular Ejection: Ejection of blood begins when
ventricular pressure exceeds arterial pressure and forces the
semilunar valves open. Rapid ejection-blood spurts out of
each ventricle and then flows out more slowly under slower
pressure (reduced ejection). T wave occurs late here.
Stroke Volume
Volume of blood pumped from one ventricle of the heart with
each beat. 3 variables govern it. PRELOAD, CONTRACTTILITY,
AFTERLOAD. Increased preload or contractility increases
stroke volume, whereas increased afterload opposes the
emptying of the ventricles and reduces stroke volume.
TERM 62
Preload
DEFINITION 62
The amount of tension in the ventricular muocardium
immediately before it begins to contract. SV is proportional
to the end diastolic volume (EDV).
TERM 63
Contractility
DEFINITION 63
Refers to how hard the myocardium contracts for a given
preload. It describes the increase caused by factors that
make the cardiocytes more responsive to stimulation.
TERM 64
Afterload
DEFINITION 64
Sum of all the forces that the ventricles have to overcome to
pump blood in the aorta and pulmonary trunk. (def-sum of all
the forces a ventricle must overcome before it can eject
blood)
TERM 65
Cardiac Tamponade
DEFINITION 65
Compression of the heart by an abnormal accumulation of
fluid or clotted blood in the pericadial cavity, intefering with
ventricular filling and potentially leading to heart failure.
Pericarditis
Inflammation of the pericardium. Often uknown cause, but
usually from infection.
TERM 67
Ventricular Septal Defects
DEFINITION 67
One or more holes in the wall (interventricular septum) that
seperates the right and left ventricles of the heart. Can be
congenital (present from birth)
TERM 68
Atrial Septal Defects
DEFINITION 68 Same but in the atria. Normally there is an opening bt. the upper chambers of the heart (Atria) to allow blood to flow aroun the lungs, this opening usually closes around the time when the baby born. If the opening does not close, the hole is called this. ASD.If the blood continues to flow between the 2 heart chambers, its called a shunt. Over time, there will be less oxygen in the blood that goes into the body.
