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Test 2 Material
Terms in this set (56)
Valve between LA and LV
Left atrioventricular valve, bicuspid valve, mitral valve
Valve between RA and RV
Right atrioventricular valve, tricuspid valve
low Oxygen, makes mouth and fingernails look blue, the blue is wavelengths of light (different O2 concentrations reflect light differently)
How does the heart get oxygen?
Blood from left ventricle goes to coronary arteries, then to capillaries, coronary veins and coronary sinus
two capillary beds joined in unison
3 in the body
1) hypothalamic-hypophyseal portal system (connects hypothalamus and anterior pituitary)
2) Kidneys (connects afferent and efferent arterioles)
3) hepatic portal system (digestive tract to liver)
signal for contraction originates within the heart, therefore it can contract without any outside signal
unstable membrane potential of myocardial autorythmic cells, starts at -60mV. When a pacemaker potential depolarizes to threshold, the auto rhythmic cell fires an action potential
Calcium induced-calcium released
Calcium enters myocardial contractile cell through L-type Ca2+ channel=>calcium is then released from the ryanodine receptor (RyR) in the sarcoplasmic reticulum=>
Force of Heart contractions determined by
amount of Ca2+ bound to troponin, which enhances the ability of myosin to form cross bridges with actin
I sub f channels
permeable to K+ and Na+ and they allow current flow, this is was causes the unstable membrane potential of myocardial auto rhythmic cells (-60mV)
How do catecholamines affect the rate of depolarization in cells?
They bind to B1 and B2 receptors of auto rhythmic cells which increases the Na+ and Ca2+ influx, this increases the rate of depolarization
cell junctions between cardiac cells
1)desmosomes-force transferred to an adjacent cell
2) gap junctions-electrically connect cardiac cells and allow depolarization to happen quickly
What sets the pace of the heart?
SA (sinoatrial node)
AV node delay
slows down transmission of action potentials so that the atria can complete their contraction before ventricular contraction begins
Electrocardiogram (ECG or EKG)
shows that summed electrical activity generated by all cells of the heart
faster than normal heart rate (higher than 100bpm)
slower than normal heart rate (lower than 60bpm)
irregular heart beat
When does most of the blood enter the ventricles?
When the atria is relaxed! The last 20% enters the ventricle when the atria contract
"lub" and "dup" sound of the heart
"lub"-when the AV valves close
"dup"-when semilunar valves are forced closed
is there a valve between the atria and the venae cave?
NO! results in some back flow
isovolumic ventricular contaction
builds up pressure in the ventricles until the pressure in the LV is higher than aortic pressure, this open the semilunar valve and push blood into the arteries
semilunar valves close when..
ventricles repolarize and their pressure decreases, when it falls below arterial pressure, blood flows into the cusps of semilunar valves and they shut
end-diastolic volume (EDV)
maximum amount of blood that fills the heart, at the end of ventricular relaxation
about 135mL in a 70kg man
end-systolic volume (ESV)
minimum volume of blood the ventricle contains, more than half of the blood is still in the ventricle after contraction.
This acts as a safety margin, if we need more blood for any reason, a harder contraction will result in a decrease of ESV
about 65mL in a 70kg man
amount of blood pumped by one ventricle during a contraction (average about 70mL)
this increases during exercise
Heart Rate x Stroke Volume
-measures the effectiveness of the heart
average is about 5L/min
How does EDV affect contractility?
If EDV is greater and more blood has flowed into the heart, the muscle stretches and ejects more forcefully, increasing contractility
degree of myocardial stretch before contraction
What contributes to venous return?
1) skeletal pump- contraction or compression of veins returning to heart
2)respiratory pump- pressure changes in abdomen and thorax during breathing (enlarged thoratic cavity during respiration develops a sub atmospheric pressure, which decreases pressure in inferior vena cava, which moves blood from theoretic veins to vena cava
3) sympathetic innervation of veins
What increases contractility?
increasing the amount of Ca2+ available for contraction
catecholamines on B1 receptors cause Ca2+ channels to open
they are positive inotropic effects
any chemical that affects contractility (can be positive or negative)
What can help with heart failure?
Heart failure-cannot contract forcefully
cardiac glycoside-it decreases the removal of Ca2+ from the cytosol by depressing the Na+-K+-ATPase of all cells (which can be toxic), but they also decrease the function of NA+-Ca2+ exchanger (NCX), which increases cytosolic Ca2+ and causes a more forceful contraction
What can increase after load?
elevated arterial blood pressure! After load is the EDV and any resistance that the ventricle experienced while trying to displace blood that is already in the aorta
membranous fluid-filled sac that they heart is encased in
collagenous tendon that the flaps in the AV valve attach to
provide stability for the chordae tendineae
part of intercalated disk, transfers force from cell to cell
the only pathway through which action potentials can reach contractile fibers of the ventricles
Conducting system of the heart
SA node-internodal pathways-AV node-AV bundle-Bundle branches- Purkinje fibers- depolarization wave spreads upward from the apex
The force/tension created by striated muscle is directly correlated to what?
the starting length of the sarcomere (aka EDV)
site of variable resistance in CV
they can vasodilate or vasoconstrict
volume reservoir and pressure reservoir in CV
systemic veins serve as a volume reservoir, systemic arteries serve as a pressure reservoir
where does exchange between the blood and the cells take place?
the inner lining of all blood vessels, secretes paracrine signals and helps regulate blood pressure
when relaxed, blood flowing into a met arteriole is directed into adjoining capillary beds. If constricted, met arteriole blood bypasses the capillaries and goes directly to the venous circulation
skeletal muscle pump
skeletal muscles compress the veins and force blood toward the heart
what is the primary determinant of velocity of flow
What are the muscles of inspiration
3) external intercostals
What are the muscles of expiration
2) abdominal muscles
percentage of red blood cells to total blood volume
double membrane surrounding the lung, it is like a fluid-filled balloon surrounding an air-filled balloon
anatomic dead space
conducting airways that don't exchange gases with the blood
Which is more water-soluble? CO2 or O2?
in CO2 transport from cells after cellular respiration to venous blood, 70% of the CO2 is converted to bicarbonate. The chloride shift is chloride entering the red blood cell so that bicarbonate can move into the plasma
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