The Cardiovascular System 2 Flashcards
explain congestive heart failure
impaired ability of heart to pump blood so it backs up
explain systemic edema
occurs when right ventricle is impaired
more blood remaining in systemic circulation
explain pulmonary edema
occurs when left ventricle is impaired
more blood remains in pulmonary circulation and in lungs
define cardiomegaly
heart becomes enlarged due to high blood pressure and/or coronary heart disease
less overlap of myofilaments so less forceful contraction
define hypertrophic cardiomyopathy
heart walls grow inwards which narrows opening for blood to pass through
decreases cardiac output
what does the right marginal branch supply
right heart boarder
what does the posterior interventricular artery supply
posterior left and right ventricles
what does the circumflex artery supply
left atrium and ventricle
what does the anterior interventricular artery supply
anterior surface of ventricles and most of interventricular septum
when is the coronary circulation flowing
between heart contractions
define arterial anastomoses
connections between vessels allowing blood to arrive by more than one route
aka detour
do all coronary veins dump into the coronary sinus
no, some dump directly into the right atrium
define coronary heart disease
when cholesterol deposits in the heart arteries (atherosclerosis) and causes inflammation
define coronary spasm
sudden narrowing of vessels caused when muscles in your heart’s arteries suddenly tighten up and restrict blood flow
leads to angina or myocardial infarction
define angina pectoris
chest pain caused by reduced blood flow to the heart
can be caused by coronary artery disease that flares during strenuous activity
felt on left side of body and is treated with vascular dilation
define myocardial infarction
heart attack
sudden and complete occlusion of coronary artery
amount of dead tissue determines severity
what are cardiac conducting cells and what do they do
form the conduction system of the heart
only 1% of all cardiac cells
don’t contract because they don’t have sarcomeres
initiates and propagates action potentials
what are cardiac contractile cells and what do they do
initiate action potentials and contract
99% of cardiac cells
contractile cells with sarcomeres
generate force to push blood out of heart
what are gap junctions and what do they do
protein pores between sarcolemma of adjacent cells
allows flow of ions and action potential between the cardiac contractile cells
what are some features of cardiac contractile cells
short
branched
interconnected
uninucleated
striated
supported by endomysium (areolar connective tissue)
what are some features of the sarcolemma
plasma membrane of a sarcomere
forms t-tubules extending into sarcoplasmic reticulum that overlie Z-discs
what are some features of the sarcoplasmic reticulum
surrounds bundles of myofilaments (myofibrils)
stores calcium
no terminal cisternae or triads
what are some features of myofilaments
arranged in sarcomeres
thin and thick filaments
organization gives striated appearence
what is the functional unit of muscle contractile cells
sarcomeres
when is the optimal length of a sarcomere in a cardiac contractile cell vs skeletal muscle cell
cardiac muscle cell: when ventricles are stretching and filling
skeletal muscle cell: at rest
difference in the length-tension relationship
what do intercalated discs do
link cardiac contractile cells together mechanically and electrically
have desmosomes and gap junctions
what are desmosomes
mechanical junctions between protein filaments to prevent cardiac muscle cells from pulling apart
act like Velcro
what does myoglobin do
globular protein that binds oxygen when the muscle is at rest
what does creatine kinase do
catalyzes the transfer of phosphate from creative phosphate to ADP yielding ATP and creatine
what is the main function of the conduction system
allows impulses to travel much faster to cause effective pumping
define autorhythmicity
ability of cardiac conducting cells to spontaneously depolarize
no need for brain’s input
what is the sequence of excitation
SA node, AV node, atrioventricular bundle, right and left bundle branches, and purkinje fibers
what are some features of the SA node
found in the superior right atrium near the opening of the superior vena cava
primary pacemaker that initiates and sets heartbeat
initiates depolarization
what prevents the SA node from making the heart beat 100 bpm
nerves (vagal tone) in the heart
parasympathetic activity that keeps our resting heart rate slower
what does the internodal pathway do
pathway between SA and AV node that allows the action potential to travel between the two
what does the Bachmann’s bundle do
allow action potentials to spread from right to left atrium
allows the atria to depolarize together
what are some features of the AV node
found on the floor of the right atrium
passes depolarization to the ventricles
why is there a 0.1 second delay before the AV node sends the action potential to the AV bundle
AV node has fewer gap junctions
AV node fibers have a smaller diameter which means a slower conduction speed
delay allows atria to contract and finish ventricular filling
what are some features of the atrioventricular bundle
aka bundle of His
goes from AV node, through right ventricle, and into the interventricular septum where it divides into left and right bundle branches
what are some features of right and left bundle branches
found along the interventricular septum and excites its cells
sends impulses towards heart apex
what are some features of the purkinje fibers
run along the margin of the ventricles
spreads action potentials through the ventricles towards the base of the heart
what are the two events of heart contraction
conduction system that initiates and propagates action potentials (depolarization)
cardiac contractile cells that contract
what is pacemaker potential and in which cardiac cell would you find this
spontaneously changing membrane potentials that initiate action potentials
found in cardiac conducting cells
define action potential
sequence of changes in the voltage across a membrane to trigger rhythmic contractions of heart
occurs at threshold
explain the electrical events of cardiac contractile cells
explain electrical events of cardiac conducting cells
explain the mechanical events of cardiac contractile cells
define tetany
sustained contraction
only seen in skeletal muscle cells
explain the absolute refractory period of cardiac cells
cardiac muscle cells have long absolute refractory periods meaning cell cannot fire new action potential during refractory
longer refractory period because of plateau
allows the heart to relax and fill
what is excitation contraction coupling in skeletal muscle
acetylcholine causes action potential to begin excitation contraction coupling
calcium released from sarcoplasmic reticulum due to voltage changes (voltage activated calcium release (VACR))
what is excitation contraction coupling in cardiac muscle
action potential originates spontaneously in heart’s SA node
calcium released from sarcoplasmic reticulum is used for muscle contraction, very little comes from extracellular fluid (calcium activated calcium release (CACR))
what is the optimal length of a sarcomere
when there is a maximum overlap of actin and myosin
most amount of cross bridges can be formed
explain why cardiac contractile cell’s optimal sarcomere length is when the heart is filling
heart fills and stretches, more stretching means more cross bridge formation, more cross bridge formation means more forceful contraction, more forceful contraction means more stroke volume, more stroke volume means more cardiac output
define functional syncytium
another word for heart chamber
named this way because it functions as a singular unit
define ischemia
poor blood flow, specifically to the heart muscle cells in our case
explain the differences and similarities between the electrical events of both conducting and contractile cells
conducting: no resting phase (unstable resting membrane potential), RMP is -60 mV, threshold is -40mV, T-type channels
contractile: plateau phase, immediate rapid depolarization, stable resting membrane potential, RMP is -90 mV, no t-type channels
where is the cardiovascular control center located
medullar oblongata
what are the three parts of the cardiovascular control center
cardioinhibitory center (CI)
cardioacceleratory center (CA)
vasomotor center (VM)
where does the cardiovascular control center receive signals from
afferent nerves from:
higher brain centers
proprioreceptors (position)
baroreceptors (stretch)
chemoreceptors (chemicals)
along which pathways does the cardiovascular center send signals out to the peripheral nervous system
efferent nerves
parasympathetic (vagus and vasomotor nerves)
sympathetic (cardiac accelerator nerves)
explain how the cardioinhibitory center (CI) works
parasympathetic center
decreases heart rate by inhibiting SA and AV node via the vagus nerve
right vagus nerve does SA node
left vagus nerve does AV node
**has no effect on strength of contraction
explain how the cardioacceleratory center (CA) works
sympathetic center
increases heart rate and contraction strength by stimulating SA node, AV node, and muscle contractile cells using sympathetic cardiac nerves
explain how the vasomotor center (VM) works
sympathetic center
affects constriction and dilation of systemic vessels
most blood vessel smooth muscle cells have a1 adrenergic receptors
some blood vessel smooth muscle cells have b2 adrenergic receptors
NE and EPI bind to a1 to cause vasoconstriction
NE and EPI bind to b2 to cause vasodilation
