Lecture 1 -- Exam 2 Flashcards
What side of the heart has the highest pressure?
left heart
What side of the heart has oxygenated blood?
left
Which side of the heart has de-oxygenated blood?
right
Do veins or arteries bring blood to the heart?
veins
Do veins or arteries carry oxygenated blood?
arteries
Do veins or arteries take blood away from the heart?
arteries
What chamber of the heart is mainly responsible for pumping the blood?
ventricles
Is diastole relaxed or contracted state?
relaxed
Is systole relaxed or contracted state?
contracted
What are the 2 semilunar valves?
aortic valve
pulmonary valve
What are the 2 AV valves?
mitral valve
tricuspid valve
Where are the semilunar valves located?
between ventricles and arteries
Where are the AV valves located?
between atrium and ventricles
What is the role of the chordae tendineae?
keeps AV valves closed to prevent back flow into the atrium
What is thee role of the papillary muscles?
controls chordae tendineae on the AV valves
When are the chordae tendineae pulled taught like a parachute?
when ventricles contract valve balloons up to prevent blood from going back into the atrium
What are the 4 blood vessel structures?
arteries
arterioles
capillaries
veins
What blood vessel structure is referred to as the “pressure reservoir” and why?
arteries
store pressure generated during systole and release it during diastole
Do arteries stretch to accommodate the pressure during ventricular diastole or systole?
systole
Are arterioles elastic? Why or why not?
No, they have smooth muscle around them that allows for contractions and relaxation
What blood vessel most regulates blood pressure?
arterioles (due to their smooth muscles)
What blood vessel is the site of gas and nutrient exchange with tissue?
capillaries
What blood vessel has only endothelium (no smooth muscle or elastic tissue)?
capillaries (need to diffuse nutrients easily)
Why are capallaries located everywhere?
uses diffusion for exchange of nutrients which only works with short distances
What is the purpose of the pre-capillary sphincters?
diverts blood flow during fight or flight response
What blood vessel has a large diameter and thin walls?
veins
What blood vessel is referred to as the “volume reservoir” and why?
veins
contains the highest volume of blood
Why do veins have valves?
prevent blood from pooling in legs (valves pop opened when muscles contraction)
What blood vessel has valves?
veins
What blood vessel has the most surface area and why?
capillaries
does lots of diffusion
What blood vessel has the highest blood volume?
veins
What are the 4 steps to electrical signals spreading through the heart?
- SA node
- AV node
- His bundle
- purkinje fibers
What node has the slowest conduction in the heart and why?
AV node
allows time for ventricles to fill
What are the 4 steps to a SA node action potential?
- hyperpolarization activates HCN channels– slow entry of Na+ via HCN channels and Ca2+
- depolarization – rapid influx of Ca2+ into cell
- Ca2+ channels close
- repolarization – K+ channels open and K+ leaves cell
How is the SA node trigger to fire an action potential?
spontaneously triggered
due to unstable resting potential due to initial opening of HCN (Na+) channels that sensitive to hyper polarization
HCN channels are sensitive to what 2 things?
- cAMP
- hyperpolarization
What is the process of a SA node action potential in the sympathetic response?
- sympathetic nerves secrete epinephrine
- epinephrine binds to B1 receptor
- adenylate cyclase is stimulated and creates cAMP
- more HCN channels open since more cAMP is present
- faster heart rate
What is the process of a SA node action potential in the parasympathetic response?
- parasympathetic nerves secrete acetyl choline
- acetyl choline binds to M2 receptor
- M2 receptor inhibits adenylate cyclase so no cAMP is made
- less HCN channels open since no cAMP is present (less Ca+ influx)
- lower heart rate
Does adenylate cyclase activity increase or decrease heart rate and why?
increase HR
produces cAMP which opens more HCN channels
During the parasympathetic response, HCN channels only rely on ______________ and not cAMP levels
hyperpolarization
Does cAMP increase or decrease HR?
increase
Does acetyl choline increase or decrease HR?
decrease
What are the 5 steps of Atria/Ventricular action potentials?
- depolarization – Na+ channels open and Na+ enters cell
- Na+ channels close
- repolarization – K+ channels open and K+ leaves cell
- platue phase – Ca2+ channels open and Ca+ enters cell while K+ is still leaving
- repolarization – Ca+ begin to close and K+ channels dominate
What is the absolute refractory period?
Na+ channel are closed and no stimulus can activate a new action potential
What is the effective refractory peroid?
Na+ channels begin to recover (some Na+ influx) but not enough for a new action potential
What is the relative refectory period?
requires a larger than normal stimulus for a new action potential
What is the supranormal refractory period?
membrane is more excitable than normal because membrane potential is closer to threshold than resting potential
* easier to start a new action potential than normal
What is an ECG?
measures differences in skin potentials that reflect electrical activity in the heart (sum of all action potentials)
What happens during the P wave on an ECG?
atrial depolarization (contraction)
What happens during the PR segment on an ECG?
conduction through the AV node and bundles
What happens during the QRS complex of an ECG?
ventricular depolarization (contraction)
What happens during the T wave of an ECG?
ventricular repolarization (relaxed)
During a SA node action potential, the beginning slow influx of Na+ is referred to as…
funny current (If)
Depolarization means contraction of releaxed?
contraction
Repolarization means contraction or relaxed?
relaxed
What is referred to as the volume of blood flowing through any tissue at a given time?
blood flow
What is referred to as the volume of blood circulating through the vessels each minute
cardiac output
What is the equation for cardiac output?
CO = HR x SV
heart rate x stroke volume
What is stroke volume?
the volume of blood pumped out of the heart’s left ventricle during each systolic cardiac contraction
How do you calculate stroke volume?
end diastolic volume - end systolic volume
What is end diastolic and systolic volume?
end diastolic volume: volume of blood in ventricles once they fill (after atrium contracts)
end systolic volume: volume of blood left after ventricle contraction
What 3 things is stroke volume determined by?
- preload
- afterload
- contractility
The higher the resistance to blood flow the _______ the blood flow
smaller
The greater the pressure difference, the __________ the blood flow
greater
Is blood velocity higher or low in narrow tubes?
higher
Fluid flows only if there is a _________ pressure gradient
positive
Fluid flow depends on the magnitude of the ___________ ___________ rather than the overall pressure
pressure gradient
When fluid begins to flow through a system, the pressure falls with distance as energy is lost to ___________
friction
Is the pressure farther away from the heart higher or lower than the pressure near the heart?
lower
The path of blood through arteries to arterioles to capillaries to veins is known as ___________ resistance while the path of blood through just capillary beds is referred to as _________ resistance
series
parallel
Cardiac output depends on what 2 things?
- pressure differences
- vessel resistance flow
What is the main determining facor of blood velocity?
diameter of blood vessel (narrower the faster)
What is total peripheral resistance?
cumulative resistance of thousands of vessels in the body
The total peripheral resistance is roughly equal to resistance of the __________
arteriole (resistance vessel)
What is the one exception to the rule that the total peripheral resistance is roughly equal to resistance of the arterioles
lungs (low pressure system)
What is Poiseuille’s Law?
resistance = 1 / (vessel radius)^4
Small changes in vessel diameter/size has a significant effect on flow _______
rate
If the radius of a vessel is doubled the flow increases or decreases 16-fold?
increases (more open the vessel the more can flow through)
What affects the flow resistance the most?
radius of vessel
What is vascular distensibility?
ability of vessels to stretch under pressure
** all blood vessels are distensible
What blood vessel is the most distensible and why?
veins
contains the most amount of blood
Why won’t you loose much blood if you cut a vein compared to an artery?
veins have lower pressure
Are small or large vessels the dominant contributers to flow resitance?
small
Flow regulation is accomplished by vasodilation and vasoconstriction in the __________
arterioles
Blood flow from areas of _________ to _________ pressure
high to low
Blood flow is opposed by the ____________ of a system
resistance
What 3 factors affect resistance?
radius of vessels
length of vessels
viscosity of blood
What unit is flow measured in?
L/min
mL/min
What unit is velocity measured in?
cm/min
mm/sec
