Exam 2 Flashcards
Cardiovascular system
Base of the heart
Superior. Major vessels. 1.2 cm to left. 3rd costal cartilage.
Apex of the heart.
Pointed tip. Inferior. 12.5 cm from base. 7.5 cm to left. 5th intercostal space.
The heart is a ___ sided pump with ____ chambers
2 ; 4
Right atrium _____ blood ____
receives ; from systematic circuit
Right ventricle ____ blood ______
pumps ; into pulmonary circuit
Left atrium _____ blood _____
receives ; pulmonary circuit
Left ventricle _____ blood _____
pumps ; into systematic circuit
The heart is located in the ______ and is enclosed by the ________
mediastinum ; pericardial cavity
Mediastinum
space or region in thorax between 2 pleural cavities (between the lines)
Pericardium
Sac like structure wrapped around heart
Fibrous pericardium
outermost layer; dense fibrous tissue that extends to sternum and diaphragm
Serous pericardium
2 layers. outer layer lines fibrous pericardium. inner serous layer covers surface of heart
Pericardial cavity
space between serous layers; 15-50 mL of pericardial fluid, lubricates movement of heart
Cardiac tamponade
excess accumulation of pericardial fluid
Epicardium
Visceral layer of serous pericardium.
Myocardium
middle layer
Endocardium
innermost layer, simple squamous epithelium and areolar tissue. covers chambers, vessels, and heart valves.
Atrial musculature
Located in myocardium. wrap around atria in figure 8 pattern
Ventricular musculature
In myocardium. surrounds both ventricles.
Cardiac muscle
Smaller than skeletal. 10-20 um diameter; 50-100 um length, intercalated discs. intercellular connections. single, centrally located nucleus. striated. almost totally dependent on aerobic metabolism (needs oxygen for energy). Abundant mitochondria and myoglobin (Stores O2). extensive capillaries.
Intercalated discs
branching interconnections between cells. attached by desmosomes and gap junctions.
Gap junctions
allow action potentials to spread cell to cell; allows all interconnected cells to function together as single unit = a functional syncytium
Auricle of each atrium
expandable pouch
Coronary sulcus
Anterior view. groove separating atria and ventricles
Ligamentum arteriosum
Anterior view. fibrous remnant of fetal connection between aorta and pulmonary trunk
Pulmonary veins
Posterior view. return blood to left atrium
superior and inferior venae cavae
posterior view. retuning blood to right atrium
Coronary sinus
Posterior view. returns blood from myocardium to right atrium.
posterior inter-ventricular sulcus
posterior view. groove between 2 ventricles
Left and right coronary arteries
arise from ascending aorta; fill when ventricles are relaxed (diastole)
Myocardial blood flow may increase to ___ times the resting level during maximal exertion
9
Right coronary artery
-right atrium, parts of both ventricles, parts of cardiac (electrical) conducting system. follows the coronary sulcus (groove between atria and ventricles) main branches: 1. marginal arteries (right ventricle supply) 2. posterior inter ventricular artery (posterior depending) - this runs in posterior IV sulcus; supplies IV septum
Left coronary artery
supplies left ventricle, left atrium, inter-ventricular septum. -main branches: 1. anterior inter ventricular artery (left anterior depending artery): follows anterior IV septum, supplies IV septum. 2. circumflex artery: follows coronary sulcus to the left, meets benches of right coronary artery posteriorly; marginal artery off circumflex supplies posterior of left ventricle.
Coronary circulation - veins (anterior)
- great cardiac vein ( in anterior IV sulcus): drains areas supplied by the anterior IV artery, empties into coronary sinus
- anterior cardiac veins: drain anterior surface of right ventricle, empty directly into right atrium
Coronary circulation - veins (posterior)
- coronary sinus- expanded vein that empty into right atrium
- posterior vein of left ventricle - drains area supplied by circumflex artery
- middle cardiac vein - drains area supplied by posterior IV artery; empties into coronary sinus
- small cardiac vein: drains posterior of right atrium/ ventricle, empties into coronary sinus.
Blood flow through the coronary circuit is maintained by changing _____ and _____
blood pressure ; elastic rebound
left ventricular relaxation
pressure decreases, aortic walls recoil (elastic bound) pushing blood in both directions (forward into systematic circuit and back into coronary arteries)
left ventricular contraction
forces blood into aorta, elevating blood pressure, stretching aortic walls
Atrium
receives blood
Ventricle
pumps blood out of heart
Right and left atria are separated by the _____
interatrial septum
Right and left ventricles are separated by the ______
interventricular septum
Semilunar valves
at exit from each ventricle; allow only one-way blood flow from ventricle out into aorta or pulmonary trunk
Right atrium
receives Deoxygenated blood from vena cava and coronary sinus. (from systematic circuit) -fossil ovals: eminent of fetal foramen ovale that allowed fetal blood to pass between atria; closes at birth. passes to right ventricle to pulmonary circuit.
Left atrium
receives oxygenated blood from pulmonary veins. sends to left ventricle to systematic circuit.
pectinate muscles
muscular ridges located inside both atria along the anterior atrial wall and in the auricles
right ventricle
thinner wall; minimal effort. receives blood from right atrium through tricuspid valve or right atrioventricular valve, with contraction blood exits through left pulmonary valve (semilunar) into pulmonary trunk
left ventricle
much thicker than right. 4-6 times the pressure of right; sends blood to entire systematic circuit. reduces right ventricular volume, aiding its emptying. receives blood from left atrium through mitral valve or bicuspid. with contraction blood exits through aortic valve (semilunar ) into the ascending aorta.
trabecular carnae
muscular ridges inside both ventricles
Valve structure: cusps attach to tendon-like connective tissue bands called _____
chorde tendineae
chorde tendineae are anchored to thickened cone shaped _____
papillary muscles
moderator band
thickened muscle ridge providing rapid conviction path; tenses papillary muscles just before ventricular contraction; prevents slamming or inversion of AV valve
Artia have ____ workloads. walls ______
similar; about the same thickness
Venticles have _____ workloads
different.
When ventricles are relaxed they ____
fill. AV valves open. chord tendineae are loose. semilunar valves closed.
When ventricles contract they ______
empty. AV valves close, papillary muscles tighten chord tendinae so cusps cant invert into atria, prevents backflow. semilunar valves open.
Cardiac cycle
period between start of one heartbeat and the next
heart rate
number of beats per minute
Two ____ contract to fill ventricles
atria
Two ______ contract to pump blood into pulmonary and systematic circuits
ventricles
Systole
blood leaves chamber
diastole
chamber refills
sequence of contractions
- Atria contract together first (atrial systole)
Push blood into the ventricles
Ventricles are relaxed (diastole) and filling - Ventricles contract together next (ventricular systole)
Push blood into the pulmonary and systemic circuits
Atria are relaxed (diastole) and filling.
Typical cardiac cycle lasts 800 msec
Cardiac cycle is in detail is on slides 57-64
powerpoint.
Dicrotic notch
a valley in pressure tracing
S1 Lubb
when AV valve closes; marks start of ventricular contraction
S2 dupp
when semilunar valves close
s3 and s4
very faint, rarely heard in adults. s3= blood flowing through ventricles. s4= atrial contraction
cardiac output
amount of blood pumped from the left ventricle each minute. determined by heart rate and stroke volume. precisely adjusted to meet needs of tissues.
audtorhythmicity
cardiacs muscles ability to contract at its own pace independent of neural or hormonal stimulation
conducting system
5 steps. network of specialized cardiac muscles cells ( pacemaker and conducting cells) that initiate / distribute a stimulus to contract
Conducting system step 1
sinoatrial node: pacemaker. each heartbeat begins with AP generated here. in posterior wall of right atrium, near superior vena cava. impulse is initiated here and spreads through adjacent cells. 60-100 bpm.
Conducting system step 2
Internodal pathways: formed by conducting cells. distribute through both atria
Conducting system step 3
Atrioventricular node: at junction between atria and ventricles. relays signals from atria to ventricles. has pacemaker cells that can take over pacing if SA node fails. AV pacing is slower. 40-60 bpm
Conducting system step 4
AV bundle: conducting cells transmit signal from AV node down through IV septum. usually only electrical connection between atria/venticles
Conducting system step 5
bundle branches: right and left branches. left are larger. conducting cells transmit signal to apex of heart, then spreading out in ventricular walls
Conducting system step 6
Purkinje fibers: radiate upward through ventricular walls. large diameter conducting cells. propagate action potentials as fast as myelinated neurons. stimulate ventricular myocardium and trigger contraction
P wave
atrial depolarization
QRS complex
ventricular depolarization. ventricles contract after R peak,
T wave
ventricular repolarization
P-R interval
start of atrial depolarization to start of ventricular depolarization
Q-T interval
ventricles undergo single cycle.
ECG’s are valuable for detecting
arrhythmias
Cardiac arrhythmias
abnormal patterns of cardiac electrical activity
premature atrial contractions
occur in healthy people, stews, caffeine, various drugs increase permeability of the SA pacemaker.
paroxysmal atrial tachycardia
premature atrial contraction triggers flurry of arial activity ventricles keep pace. heart rate jumps to about 180 bpm
atrial fibrillation
up to 500 bpm. atria quiver-not organized contraction. ventricular rate cannot follow, may remain fairly normal. atria nonfictional but ventricles remain fairly normal. person may not realize.
premature ventricular contraction
purkinje cell or ventricular myocardial cell depolarizes, triggers premature contraction. cell responsible is called exotic pacemaker . increased by epinephrine, drugs, or ionic changes that depolarize cardiac muscle cells
ventricular tachycardia
4 or more PVCs without intervening normal beats. multiple PVCs and Vtach may indicate serious cardiac problems
ventricular fibrillation
fatal because ventricles quiver quicker but cannot pump any blood. cardiac arrest.
pacemaker potential
the gradual spontaneous depolarization . cells are in SA and AV nodes
Pacemaker in SA node
80-100 times/min. establishes heart rate. SA node brings AV node cells to threshold before they reach it on their own, thus SA node paces the heart
Parasympathetic stimulation decreases heart rate. t or f
true
ACh from parasympathetic neurons:
opens K+ channels in plasma membrane, hyper polarizes membrane, slows rate of spontaneous depolarization, lengthen repolarization
Sympathetic influence
increase heart rate. binding of norepinephrine to beta1 receptors opens ion channels. increases depolarization, decreases repolarization
resting heart rate
varies with age, general health and physical condition. normal is 60-100 bpm.
bradycardia
hr is slower than normal <60
tachycardia
hr is faster than normal >100
heart failure
conditions in which the heart cannot meeting the demands of peripheral tissues
blood vessels
conduct blood between the heart and peripheral tissues
capillaries
exchange substances between blood and tissues, interconnect smallest arteries and smallest veins . thin walls allow easy diffusion
pulmonary circuit
p arteries to p capillaries to p veins
systematic circuit
s arteries to s capillaries to s veins
there are four layers of arteries and veins t or f
false ; 3
tunica intima
innermost. elastic fibers.
tunica media
middle. smooth muscles. contraction=decrease in vessel diameter or vasoconstriction. relaxation=increase or vasodilation.
tunica externa
outermost. collagen and elastic fibers. in veins, thicker than media (contains networks of elastic fibers and bundles of smooth muscle) anchors vessel to surrounding tissue
elastic arteries
large vessels that recoil when heart beats pulmonary trunk, aorta, and branches
muscular Arteies
medium. blood to skeletal muscles and internal organs
arterioles
poorly defined externa. 1-2 smooth muscle cells thick
venules
small veins. those smaller than 50 um lack a media and resemble capillaries. collect blood from capillaries
medium sized veins
2-9 mm in internal diameter. thin media with smooth muscle and collagen. thickest layer is externa
large veins
contain all 3 vessel wall layers. superior and inferior vena cava.
capillary bed
interconnected network of capillaries. connections between arterioles and veils . can be supplied by more than one artery. allows continuous delivery of blood to capillary bed even if one artery is blocked. can be bypassed by arteriovenous anastomosis that directly connects arteriole to venue. this is regulated by sympathetic intervention.
collaterals
multiple arteries
fusion is an example of
arterial anastomosis
anastomosis
joining of blood vessels
metarteriole
initial segment of connection passageway. contains smooth muscle that can change the vessels diameter and adjust flow rate
thoroughfare channel
most direct passageway through capillary bed
precapillary spinchters
bands of smooth muscle that contract and relax to control flow into the capillary bed
vasomotion
cycles of contraction and relaxation
The venous system has low pressures and contains almost one-thirds of the body’s blood volume t o f
false. its 2/3s
Flow through blood vessels is influenced by
resistance
Capillary exchange
diffusion between blood and interstitial fluid. involves a combo of diffusion , osmosis and filtration
Blood pressure in veins is maintained by
valves and muscular compression of peripheral veins
As blood moves towards the heart vessels get ____ and resistance ____
larger / decreases
Central regulation
- Involves neural and endocrine mechanisms
- Makes coordinated adjustments to heart rate, stroke volume, peripheral resistance, and venous pressure so cardiac output is sufficient
Decreasing diameter _____ resistance and ____ pressure and _____ flow
increases / decreases / decreases
heart generates pressures of about 130 mm hg t or f
false, 120
At start of peripheral capillaries pressure is ___, at the venues pressure is ___
35 mm hg / 18 mm hg. pressure drops at each branching in arterial system.
flow ___ in venous system
accelerates. theres lower resistance bc of larger diameters
systolic pressure
pressure rises, contraction
diastole pressure
relaxation
pulse pressure
largest minus smallest. systolic minus diastolic
mean arterial pressure .
diastolic pressure plus pulse pressure / 3. 90 + (120-90) divided by 3
capillary hydrostatic pressure
pushes water and small molecules out of the blood stream into interstitial fluid . larger molecules such as plasma proteins remain in blood
