HESI Cardiovascular system Part 2 Flashcards
Within the intercalated discs, adjacent cells are connected by ___ and ____ ___
desmosomes
gap junctions
action potentials in the heart come form specialized cardiac muscle cells called ______ cells
autorhythmic cells
The autorhythmic cells are concentrated in 2 areas, the ___ __ and the ___ ___
sinoatrial node
atrioventricular node
The sinoatrial node is located in the
right atrium
The atrioventricular node gets its action potential from the
sinoatrial node
The cardiac cycle is initiated by the
sinoatrial node
The atrioventricular node sends action potential to the
atrioventricular bundle (bundle of His)
The ventricles are stimulated by impulses from the ___ ___
atrioventricular bundle
the ___ ___ conduct the action potential from the inter ventricular septum down to the apex and back up through the ventricles
purkinje fibers
the first step in cardiac muscle contraction, depolarization occurs when channels open to allow ___ to enter
Na+
the second step in cardiac muscle contraction, ___ enters the cytosol from the sarcoplasmic reticulum and also form outside the cell
Ca2+
Within the cell, Ca2+ binds to
troponin
Once Ca2+ binds to troponin, this stimulates ___-___ binding which leads to the sliding of actin filaments past myosin filaments
cross-bridge
repolarization occurs as ___ channels opens and ___ diffuses out of the cell
K and K
Compared to skeletal muscle, the refractory period of cardiac muscle is
longer, ensuring each contraction is followed by enough time to allow the heart chamber to refill with blood before the next contraction
In an ECG, the ___ wave is small, representing the depolarization of the atria.
P
During this wave, muscles of the atria are contracting
P
ECG, a rapid down-up-down movement
QRS
Represents the depolarization of the ventricles
QRS
represents the repolarization of the ventricles
T
A contraction event (of either atria or ventricles) is called
systole
a relaxation event is referred to as
diastole
The ___ ventricular relaxation is the period during which the ventricles are released and the AV and semilunar valves are still closed. The volume of the ventricles remains unchanged
isovolumetric ventricular relaxation
Ventricular filling begins as the AV valves open and blood fills the ventricles. The ventricles remain in ___ during this time
diastole
Blood fills the ventricles in 3 phases. First it flows in quick since there’s plenty of space. Second it flows slower since there’s less room. Third, atrial systole forces the last of the blood in. The final amount of blood at this point is called the ___ ___
end-diastolic volume
Ventricular contraction (systole) starts as the action potential form the ___ node enters the ventricle.
AV node
___ contraction occurs when the AV valves are forced shut. During this brief period, while semilunar valves are still closed, the volume of the ventricles remains unchanged
isovolumetric contraction
The amount of blood remaining in the ventricles after relaxing is the ___ ___
end-systolic volume
___ ___ is the volume of blood ejected by each ventricle during a single contraction
stroke volume
___ ___ is the number of heartbeats per minute
heart rate
___ ___ is the volume of blood pumped out of the right or left ventricle per minute
Cardiac output
If you’re in really good shape, your cardiac output while exercising could be 7 times your cardiac output during resting! The ratio between the maximum and resting cardiac output is called the ___ ___
cardiac reserve
a factor of stroke volume is ___, which is the degree to which cardiac cells are stretched by blood entering the chambers
preload
a factor of stroke volume is ___, the degree to which cardiac cells contract as a result of extrinsic influences
contractility
a factor of stroke volume is ___ which is a measure of the pressure that must be generated by the ventricles to force the semilunar valves open
afterload
The greater the after load, the smaller the stroke volume. ___ (which is narrowing of blood arteries) and high blood pressure increase after load and reduce stroke volume
arteriosclerosis
The ___ nervous system may influence heart rate
autonomic
blood vessels have 3 layers, tunica ___, tunica ___, tunica ___
tunica intima
tunica media
tunica adventitia
The inner layer facing the blood
tunica intima
tunica media is made of ___ ___
smooth muscle
tunica adventitia is made of ___ tissue
connective tissue
3 kinds of arteries
Elastic, muscular, arterioles
The biggest kind of artery
elastic artery
capillaries are microscopic with very thin walls, they only have 1 layer which is the tunica ___
intima
type of capillary, the blood vessels between arterioles and venules.
metarterioles (precapillaries)
metarterioles (precapillaries) are not true capillaries because they have __ __
smooth muscle
type of capillary, makes up the bulk of the capillary bed
true capillary
true capillaries don’t have muscle in their walls, but they do have a ring of smooth muscle (fact)
nothing
three kinds of true capillaries
Continuous
Fenestrated
Sinusoidal
most common true capillary
continuous capillary
true capillary with pores (fenestrations)
fenestrated capillary
type of capillary used in the kidney because it is especially porous
fenestrated capillary
true capillary that has large gaps that allow blood cells to pass through. Found in the bone marrow, spleen, liver
sinusoidal capillary
3 kinds of veins
postcapillary venule
venules
veins
type of vein thats very porous with scattered smooth muscle
postcapillary venule
In veins, the tunica intima and tunica media are ___ compared to arteries
thinner
One thing veins have that arteries dont
valves (to prevent back flow)
Many regions of the body receive blood supplies from 2 or more arteries. The points where these arteries merge are called arterial ___
arterial anastomoses
the pressure measured during contraction of the ventricles
systolic pressure
systolic pressure average ___ mm Hg in arteries of the systemic circulation
110
the pressure measured during ventricular relaxation
diastolic pressure
diastolic pressure averages ___ mm Hg
75
Blood pressure is basically ___ mm Hg in the veins
0
Because there’s no blood pressure in the veins, 2 pumps move the blood
muscular pump
respiratory pump
veinous pump, arises from contractions in skeletal muscle surrounding veins (squeezes them and the blood has no where else to go because of the valves)
muscular pump
veinous pump, moves blood by pressure changing during inhalation
respiratory pump
the part of the brain that regulates blood pressure
medulla oblongata
The cardiovascular center receives information about the state of the body from 3 sources
Baroreceptors
Chemoreceptors
Higher brain regions
sensory neurons that monitor arterial blood pressure
Baroreceptors
sensory neurons that monitor levels of CO2 and O2
chemoreceptors
The ___ provide a hormonal mechanism for the regulation of BP by managing blood volume
kidneys
In response to rising blood pressure, cells in kidneys secrete ___ into the blood
renin
___ and ___, hormones secreted by the adrenal medulla, raise blood pressure by increasing heart rate and the contractility of the heart muscles. These hormones are secreted as part of fight-or-flight response
epinephrine and norepinephrine
___ hormone, a hormone made by the hypothalamus and released by the posterior pituitary, raises blood pressure by stimulating the kidneys to retain water
Antidiuretic hormone
___ ___ ___, a hormone secreted by the atria of the heart, lowers blood pressure by causing vasodilation and by stimulating the kidneys to excrete more water and Na+
Atrial natriuretic peptide
