system overview and the heart Flashcards
what are the components of the circulatory system
Heart
Blood vessels
Bloos
what are the rolls of arteries
Low resistance tubes to cary blood to organs
pressure reserve
what is the roll of arterioles
provide resistance to control where blood glows
control aterial blood pressure
what is roll of Capillaires
Major site of nutrient, metabolic end products, fluid exchange between blood and tissue
what is the roll of venules
Site of nutrient, metabolic, and fluid exchange betwen blood and tissues
what is the roll of veins
low resistance for flow back to heart
capacity for blood to be adjusted to faciliate flow
what is the liquid portion of blood
Plasma
what is found in the plasma
dissolved nutrients, ions, waters, gases, other substances
- similar to interstitial fluid at capillaries
what does the blood constist of
Formed elements (cells and cell fragments) Liquid (plasma)
what cells are included in blood
RBC white blood cells - neutrophils - B cells - T cells - monocytes - eosinophils - baseophils Platelets
what s the meatocrit
Percent of blood that is RBCs
what is the average hematocrit
45%
- higher for men
- lower for women
- no idea why
what is the roll of blood
Nutreints and wastes
Hormones/info
thermal regulation - water caries a lot of heat
what is the total volume of blood equal to
Plasma+ buffy coat+ erythrocytes
what is the equation for a hematocrit
erythrocyte volume/ total volume
is fully oxygenated blood red or blue
It is red
what does the R and L sides of the heart pump
R: pulmonary
L: systemic
what is microcirculation
Aterioles
Capillaries
Venules
exchange of O2, CO2, nutrients, and metabolic end products occure at what level
Capillaries and Interstitial fluid via diffusion
do all organs receive the same amount of blood at rest
No
what is the flow equation
change in pressure/Resistance
how is resistnace related to radius
Inversely to Radius^4
what is the biggest determinant of blood flow
resistnace via change in radius
does absolute pressure control blood flow
No, only the pressure difference
valve between the R atrium and the R ventricle
Right AV valve
(tricupsid)
valve between the R ventricle and pulmonary circuit
Pulmonary semilunar valve
valve between the Left atrium and the Left ventricle
Left AV valve
bicuspid
valve betweent he Left ventricle and aorta
aortic semilular valve
what do the valves do aside from controlling the direction of blood flow in the heart
electrically insulate the heart
how is cardiac muscle different from skeletal muscle
branches
Intercallated disks with gap junctions
each myocyte contracts with each heart beat
what do the gap junctions of cardiac muscle do for them
Electrically couple the heart together
why does each myocyte contract together
because the heart is electrically coupled together ( no recruitment like in skeltal muscle)
where are muscarinic receptors in the heart
only on the atria
how does the parasympathetic system act on the heart
Via the vagus nerves to release acetylcholine on muscarinic receptors on the atria
how does the sympathetic system act on the heart
Via thoracic spinal nerves to release norepinephrine to act on beta-adrenergic receptors on the atria and the ventricles
what does the parasympathetic system do for the heart
act on the atria to decrease HR
what does the sympatheic system do for the heart
Act on the atria to increase HR
act on the ventricles to increase contractility
what aside from the nervous system can act on the heart
Epinephrine from the blood stream binds to Beta adrenergic receptors to increase HR and contractility
how does electricity flow through the heart
SA node AV node Bundle of His R and L bundle branches Purkinji fibers
where is the SA node found
in the right atrium
where does sinus rhythm begin
in the SA node
what is the roll of all other aspects of the hearts conduction system
bring electricity to the apex to do ventricular contraction upward
what happens if the cells of the SA node go away
heart continues to depolarize, but lacks sinus rhythm
how much of the conducting system must be gone for the heart to no longer pump
all of it must be gone
what causes the rapid depolarization phase of myocardium
rapid opening of voltage gated sodium channels
what causes the plateau phase of myocardial cells
slow but prolonged opening of voltage gated calcium channels
Closure of potassium channels
what is needed for the atrium and ventricles to coordinate their contractions
The AV node
what is the P wave
atrial depolarization
what is the qRS wave
ventricular depolarization
what is the T wave
repolarization of the ventricles
where is the SA node in the EKG
not present, too small to ilicit a response
why don’t we see atrial repolarization
occures during ventricular contraction, so it is not seen
what are the characteristics of ventricles contraction
contract together and efficienctly
what fibers are responsible for ventricular contraction
R and L bundle branches
purkinji fibers
what is the slowest part of atrial contraction
AV node(1.2seconds) to allow for atria to contract completelyq
what causes the repolarization phase of myocardial contraction
Opening of potassium channels
what causes the resting membrane potential of myo
Potassium
can a myocyte depolarize alone
No, b/c it has a true resting membrane potential
what is the resting membrane potential of myocytes
-80mV
what kind of potential does the SA node have
Pacemaker potential
what leads to the pacemaker potential of nodal cells
Na ions leaking through F-type channe
what is responsible for the rising phase of nodal cells
rapid opening of voltage gated Ca channels
what is responsible for the repolarization phase of nodal cells
Reopening of potassium channels
closing of ca channels
what channels are needed for the pacemaker potential
F type Channels
what does an EKG that is mising every other QRS and T mean
AV node could not be repolarized due to refractory period
what does it mean when an EKG has QRS randomly associated with P at different times
Atria and ventricles could not be coupled
what does excitation contraction coupling link
cardiac muscle cell AP to contraction via control of Ca within myocardium
what is trigger calcium
Calcium from outside the cell that causes the sarcroplasmic reticulum to release Ca
what does trigger calcium bind to
ryanodine receptors on the external surface of the sarcoplasmic reticulum
what channels allow trigger calcium to enter the cell
L-type Ca channels in T-tubules
what is needed for excitation contraction coupling in Myocardium
needs extracellular ca to depolarize and release Ca from the SR
how is skeletal ca different from cardiac
skeletal needs voltage gated Ca release
why do ventricular cells have such a long Ap compared to skeletal muscles
Plateu phase from trigger calcium
what is the importance of the plateau phase for myocardial cells
makes long refractory period to ensure no heart teatanus
- allow blood to fill ventricles
