Cardiovascular Overview Flashcards
What are the major body fluid compartments?
Intracellular fluid
Extracellular fluid - includes interstitial fluid and plasma
What is the average volume and proportion of intracellular fluid and extracellular fluid?
Intracellular = 2/3 = 30 L
Interstitial Fluid = 1/3 = 15 L (12 L in interstitial fluid and 3 L in plasma)
List three conditions provided by the CV system that are essential for regulating composition of interstitial fluid
- adequate blood flow
- optimal chemical composition
- short diffusion distances
What are the two types of circuits in terms of blood flow?
series circuits and parallel circuits
What type of circuit is used to get blood to the major organs?
parallel circuits - meaning they receive blood of identical composition and flow to individual organs can be controlled independently of the flow to other organs
What is the relationship among blood flow, blood pressure and vascular resistance?
The flow is equal to the pressure differential divided by the resistance to flow
(Q = deltaP/R)
What are the two atricoventricular valves that dictate one-way flow of blood in the heart?
the right atrioventricular valve = tricuspid valve
left atrio-ventricular valve = bicuspid or mitral valve
What valves ensure one-way flow between the ventricles and the arteries?
the semilunar valves = pulmonary and aortic valves
What are the determinants of cardiac output?
stroke volume and heart rate
What are the 5 factors essential to proper ventricular pumping action?
- contraction of individual cells must occur at regular, synchronized rhythms
- valves must be open fully
- valves must not leak
- muscle contractions must be forceful
- ventricles must fill adequately during diastole
What is the relationship between ventricular filling and cardiac output? (Starling’s Law of the Heart)
If the cardiac filling increases during diastole, the volume ejected during systole also increases (heart pumps what it receives)
What is the primary role of the CV system?
to maintain homeostasis in the interstitial fluid
What is transcapillary diffusion? Why is it not good enough?
It’s where solutes are exchanged between the plasma and interstitial fluid as the blood passes through capillaries.
it’s not good enough because it only works over short distances
What factors determine flow?
resistance and pressure difference
How does flow relate to pressure difference?
it’s directly proportional: higher pressure difference, higher flow
How does flow relate to the radius of the blood vessel?
It is directly proportional to the radius to the 4th power, 1:4.
How does flow relate to length of the blood vessel?
Intuitive - it’s inversely proportional to the length
so longer length, lower flow
How does flow relate to viscosity?
It’s intersely proportional - so higher viscosity, lower blood pressure
Which factor has the largest influence on flow in the body: radius, length, viscosity or pressure difference?
radius of the blood vessel - via resistance
What is the heart’s primary job in making sure there’s blood flow?
maintaining appropriate pressure gradients
Newly oxygenated blood from the lungs enters where?
into the left atrium
Deoxygenated blood returns to the heart into what region?
the right atrium
What cells initiate the automatic spontaneous depolarization to generate an AP and heart contraction? Where is it?
pacemaker cells in the SA node (found in the right atrium)
If most cardiac cells will depolarize when a neighbor cell does, why are electrical tracts needed for the whole heart to contract?
because this synsytium with gap junctions does not extend between the atria and ventricles - it’s just connective tissue, so you need tracts to get the message on
What electrical tract connects the right atrium to the left atrium?
Bachmann’s bundle
How does the signal get form the SA node to the atrioventricular node?
through the internodal tracts
What is different about the timing of the contractions triggered by the AV node compared to the SA node?
The RATE will be the same (when controlled by the SA node that is), but there is a slight .1 second delay until after the SA contraction
What bundle will carry the signal down to the apex?
bundle of his
What fibers will take the signal from the bundle of the his back up the lateral aspects?
purkinje fibers
What are the basic parasympathetic nervous system effects on the heart?
decreased heart rate (via SA node)
decreased AP conduction velocity (via AV node)
Decreased force of atrial contraction
What are the basic sympathetic nervous system effects on the heart?
increased HR
increased AP conduction velocity
increased force of contraction
increased rate of contraction and relaxation
Of the three main types of blood vessels, which is the pressure reservoir? which is the site of diffusion? which is the volume reservoir?
pressure reservoir = arteries
diffusion = capillaries
volume reservoir = veins
What type of flow do arteries have? Veins/
Arteries have divergent flow
Veins have convergent flow
What’s the main way sympathetic nerve activity causes a decrease in blood flow?
a reduction in radius of the vessel - the arterioles in particular
In addition to sympathetic nerve activity, what else is arteriolar smooth muscle responsibe to?
local metabolic changes - so an increase in tissue emtabolic rate leads to arteriolar dilation and increased tissue blood flow
