cardiovascular Flashcards
a single contraction of the heart
heartbeat
Create and propagate electrical
signals; “pacemaker cell”
specialized conducting cells
99% of all cardiocytes, Perform contractions
Cardiac Muscle and the Heartbeat
contractile cells
Allows the heart to maintain a regular rhythm
cardiac conduction system
“pacemaker” electrical sygnal that causes heartbeat originates within heart
myogenic
regular, spontaneous, depolarization
autorhythmic
modify heart beat
extrinsic nerves
cardiac nerves, directly to ventricular myocardium, spinal cord to cardiac nerves
sympathetic nerves
vagus nerve, slows heart rate to 70-80bpm
parasympathetic nerves
right vagal nerve to SA node, left vagal nerve to AV node
parasympathetic nerves
initiates heartbeat, sets heart rate
SA node
receives signals from SA, electrical gateway to ventricles
AV node
pathway for signals from AV node
AV bundle
divisions of AV bundle that enter inter ventricular septum
Bundle branches
spread signals throughout ventricles
purkinje fibers
travels at 1m/ sec through atria; reaches AV node
SA node
slows signals to 0.05 m/sec
AV node
-90 mv
resting potential
electrical signal causes NA+ to enter cardiocyte, voltage becomes more positive
depolarization
+30 mV
voltage peak
causes a more sustained, longer contraction in heart muscle, allows heart to fully expel blood
plateau phase
k+ exits cell, voltage becomes more negative
depolarization
cause contraction of heart, stimulated by electrical signals from conduction system, different from AP’s in skeletal muscle
action potential in cardiocytes
heart contraction
systole
heart relaxation
diastole
abnormally slow heart rate
bradycardia
abnormally fast heart rate
tachycardia
abnormal cardiac rhythm due to heart block, bundle block or total blockage
arrhythmia
caused by hypoxia, electrolyte imbalance, stimulants, stress
premature ventricular contraction
region of spontaneous firing
ectopic foci
measures electrical activity of the heart
ECG
SA node fires (atrial depolarization)
P wave
delay at AV node
PR segment
ventricular depolarization, also atrial depolarization but signal is obscured
QRS complex
ventricular systole
ST segment
ventricular repolarization
T wave
from start of atrial depolarization to start of QRS complex
P-R interval
from ventricular depolarization to ventricular repolarization
Q-T interval
SA node fires; atrial depolarization begins
P wave
delay at AV node, allows ventricles to fill with blood
P-R segment
beginning of atrial depolarization to beginning of ventricle depolarization
P-R interval
ventricular depolarization
QRS wave
ventricular systole
S-T segment
rapid, fluttering, contractions, no pumping
fibrillation
period between the start of one heartbeat and the beginning of the next
cardiac cycle
pressure of the blood against walls of blood vessels
blood pressure
BP rises
systole
BP falls
diastole
AV valves open, blood flows from a triangle to ventricles (passively fill with blood)
rapid ventricular filling and diastasis
contraction of atria, remains blood in atria is ejected into ventricles (active filling)
atrial systole
atrial systole ends, pressure in ventricles rise, AV valves close (Lub)
isovolumetric ventricular contraction
ventricular systole ends, blood is ejected from ventricles
ventricular ejection
valves close (dup)
ventricular relaxation
total volume of blood in one ventricle following relaxation
end-diastolic volume (EDV)
volume of blood ejected from ventricle
stroke volume (SV)
amount of blood remaining in one ventricle flowing ejection
end-systolic volume (ESV)
EDV (130) - ESV (60) =?
SV (70 ml)
70ml
SV
30 ml
passive filling
40ml
atrial systole
60 ml
ESV
listening to heart sounds via stethoscope
auscultation
sound caused by closing of the AV valves
S1
sounds caused by the closing of the semilunar valves
S2
faint sound associated with blood flowing into the ventricles
S3
faint sound associated with atrial contraction
S4
movement and force generated by cardiac contractions
cardiodynamics
volume pumped by each ventricle in 1 minute
cardiac output
number of beats per minute
heart rate
heart rate X Stroke volume =
cardiac output
affects heart rate and stroke volume indirectly
autonomic nervous sytem
where do cardiac centers affect heart rate
medulla oblongata
change in movement; activity HR rides before metabolic demands arise
proprioceptors
monitor blood pressure, aorta and internal carotid arteries
barorecptors
pH, CO2, oxygen, aortic arch, carotid arteries and medulla oblongata
chemoreceptors
potent cardiac stimulants
neurotransmitters
amount of tension in ventricles due to blood entering the heart
preload
ventricles eject as. such blood as they receive
frank-starling law
how hard the myocardium contracts
inotropy
tubes made of connective tissue and smooth muscle that transport blood through the body
blood vessels
carry blood away from heart
arteries
smallest branches of arteries
arterioles
exchange of gases and nutrients b/t blood and tissue
capillaries
collect blood from capillaries
venules
return blood to heart
veins
carries blood from right ventricle to pulmonary circulation
pulmonary trunk/ arteries
carries blood from left ventricle to systemic circulation
aorta
small, thin, chemical and gases diffuse across walls
capillaries
tonica intima, media, externa
layers of arteries and veins
endothelium, simple squamous epithelium
tunica intima
smooth muscle, constriction and dilation
tunica media
loose connective tissue, passageways for nerves and lymph vessels
tunica externa
exposed to higher BP, thicker walls, elastic, smaller lumen
arteries
valves, thin walls, large lumen, expand easily
veins
enlarging of vessel, relaxation of arterial smooth muscle
vasodilation
narrowing or vessel, contraction of arterial smooth muscle by ANS
vasoconstriction
pulmonary, aorta, carotid, tunica media
conducting arteries
femoral, renal, splenic, smooth muscle
distributing arteries
a bulge in an arterial wall
aneurysm
continuous, fenestrated, discontinuous
3 types of capillaries
tight junctions, intercellular clefts, blood cells cannot pass,
continuous capillaries
filtration pores in endothelial lining, rapid exchange, kidneys, intestines, choroid plexus
fenestrated capillaries
gap between endothelial cells, permit free exchange, liver
sinusoids
interconnected network of capillaries
capillary beds
metarterioles, arteriovenous anastomoses
capillary beds
ring of smooth muscles that controls flow of blood through capillaries
pre-capillary sphincter
collect blood from capillary beds
venules
contains valves, most have names (brachial, saphenous, radial)
medium veins
vena cava, jugular, renal, pulmonary,
large veins
blood returning to heart through veins
venous return
lower BP, more blood volume and gravity push blood backwards in veins
skeletal muscle pump
excess pooling of blood causing stretching of veins
varicose veins
relationship between blood volume and blood pressure
capacitance
maintenance of capillary blood flow in tissues and organs
hemodynamics
amount of blood flowing through a tissue in a given time
blood flow
rate of blood flow per given mass of tissue
perfusion
specifically, peripheral BP
blood pressure
abnormally high BP
hypertension
abnormally low BP
hypotension
keep blood moving during diastole
arterial walls
expansion and recoil maintains steady flow of blood
arterial elasticity
histamine, Bradykinin, NO, prostacylin
vasoactive chemicals
growth of new vessels
angiogenesis
baroreflexes, chemoreflexes, medullary ischemic reflexes
autonomic reflexes
pro hormone produced by liver
angiotensinogen
released in response to low BP
renin
promotes Na+ and water retention
aldosterone
movement of gases, nutrients and waste across capillary walls
capillary exchange
any state where cardiac output insufficient to meet metabolic needs
circulatory shock
inadequate pumping of heart
cardiogenic shock
low blood volume (trauma, burns, dehydration)
hypovelmic shock
poor circulation, extreme dilation
vascular shock
toxins trigger vasodilation and raise capillary permeability
septic shock
obstructed venous return (tumor/aneurysm)
low venous return
blood to and from the lungs
pulmonary circut
blood to and from the rest of the body
systemic circut
serous membrane that covers heart
epicardium
smooth inner lining of the heart
endocardium
attachment for cardiac muscles
myocardium
transfer electrical signals between cells
gap junctions
hold cells together
desmosomes
receive blood returning to the heart
R/L atrium
pump blood out of the heart and into arteries
R/L ventricles
between right atrium and right ventricle
tricuspid valves
between left atrium and left ventricle
bicuspid valve
control flow into great arteries
semilunar valves
between right ventricle and pulmonary trunk
pulmonary semilunar valve
between left ventricle and aorta
aortic semilunar valve
hardened, even calcified, does not close correctly
stenosis
connect AV valves to papillary muscles
chordae tendineae
attach chordae tendinaea; prevent prolapse of AV valves
papillary muscles
muscular ridges in ventricles
trabeculae carnae
muscular ridges in atria
pectinate muscles
receives deoxygenated blood from body and heart
right atrium
blood from head, neck, upper limbs, chest
superior vena cava
blood from trunk, viscera, lower limbs
inferior vena cava
blood returns from heart tissue
coronary sinus
receives blood from right atrium
right ventricle
receives oxygenated blood from lungs
left atrium
receives oxygenated blood from left atrium and sends oxygenated blood to aorta
left ventricle
sends oxygenated blood through entire body
aorta
great cardiac vein, middle cardiac vein, small cardiac vein
major veins of the heart
low supply of nutrients
ischemia
low supply of O2
hypoxia
cell death
infarct
