Haemodynamics Flashcards
difference between serum and plasma
- serum is blood without the clotting factors and so the haematocrit forms a clot ; whilst plasma doesnt
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what causes the viscosity of the blood
- protein and cellular components
what can change WB viscosity?
what can increased b viscocity and thickness cause?
what can cause minor changes in blood viscosity?
- leukaemia, polycythaemia ( b cancer which causes ^ RBC made)
- gangrene = death of tissue due to cut off blood supply
- C-reactive proteins CRP (measured for inflammation) , acute phase proteins
whats haemodynamics? and what dicates it ?
how does blood flow?
- movement of blood
- metabolic demands of the body
- from region of high to low pressue
whats the types of blood flow and the differences between them?
- LAMINAR ; organised streamline blood flow movement, silent. there are concentric fluid layers where the middle being the quickest since they experience the least resistance from the surrounding bv wall
- TURBULENT ; which is disorganised due to stenosis / occulsion, noisy = bruit can be heard and thrill can be felt
label this graph and what is x? alsio what can you say about the energy of turbulent flow?
what happens in stenosed arteries
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- energy is lost becase the pressure increases beyond which flow can match linearly
- turbulent flow d changing direction of the vessel (branching)
what way does fluid (blood) flow?
what does flow and pressure in circulation do? and why?
- high pressure region to low pressure region
- pulsates to maintain b supply
pressure
-force per unit area (mmHg)
whats the formula for flow
- flow = k(triangleP)
- k = conductance (measure of ease of flow)
- triangle P = pressure gradeint
- flow = triangle P/R
what is resistance?
- measure of difficulty of flow
- reciprocal of K (since K= flow)
- k- (1/k)
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whats the formular for resistanc and flow and what does it mean?
R=triangleP/K
-difference in mean pressure needed to move one unit of flow in steady speed mmHg min/L
what is darcy’s law
Flow =triangle P/R
describe the relationship between resistance and flow using this graph and formula
- since resistance is reciprocal of flow at anygiven pressure gradient increase in flow will cause decrease resistance
- pressure gradient is directlyaffected by flow since b flow is dependent on the gradeint
what happens in turbulent flow? can it follow this graph?
no it cant follow this graph because with turbulent flow theres a decrease in blood flow, and so greater resistance
- also d to the pulsatile nature of flow in large arteries alters it so it requires larger greater pressure gradient for a given flow
what factors affect resistance?
P law?
what change c biggest change in flow ?
-what decrease % c 1/2 flow?
- diameter(lumen)
- length of vessel
- viscosity of blood
- Poiseuille’s law
- R = n(viscosity of blood)L/ pie R^4
- changing the diameter of the lumen alittle will result in great changes because radius is the power of ^4so will have a big impact on flow
- 19% in radius = 1/2 flow
whats Poiseuille’s law like in Aorta? small arteries? pulmonary system?
what anatomical feature of the heart demonstrates the pulmonary system’s pressure?
- aorta ; large diameter R low length short
- smaller arteries ; High R (because biggest difference in vessel class from aorta which is carries blood at a high pressure to the arterioles ) length long diameter small
- pulmonary system ; lowest R, shorter lumen/ wider vessels
- the thinner walls of the Rv
Whats velocity in terms of fluid and units?
formula?
what is v related to r?
cross section higher in the capillaires or aorta?
is velocity higher in the capillaries / aorta? and why is this important?
- distance fluid can move in a given time (cm/s)
- F = V x A (A = cross sectional area of bv = pie r^2)
- v - inversely proportional to r^2 so v = 1 / r2 (s if diametre of lumen decrases the velocity will increase)
- higher in the capilaries because cross sectional area takes into account the number of vessel,and theres a higher number of capillaires compared to aorta, so effectively their cross section is greater than the aorta which is just 1
- lower in the capilaries because allows the movement of nutrients and fluids to the surrounding cells
describe the velocity blood vessel table
describe this graph ?
formula for pulse pressure ? and MAP?
below what pressure causes what?
- PP =SBP-DBP
- MAP = DBP + (SBP-DBP) / 3 (time weighted not just average of DBP and SBP)
- below 70mmHg = organ perfusion imparement
whats TPR? and the formula?
whats the formula for Mean aortic pressure in terms of TPR
MAP in refernce to it?
what determines MAP
total peripheral reistance = resistance in all systemic vasculature excluding pulmonary vasculator
- TPR = mean aortic pressure - central venous pressure / cardiac output (CVP is 0) so….TPR = Mean aortic pressure / cardiac output
- MAP = TPR x CO
- CO = SV x HR
what happens in terms of pressure changes in ; haemorrhage and age increase?
- Haemorrhage = decrease in pressure / age = stiffening of the aorta so decrease in pressure
differnce between a bounding pulse and palpating pulse?
what is the effect of hot bath on bp?
what can be hear and felt with b flow measure?
x sounds?
- strong pulse pressure graph
- vasodilation = decreased pp
- bruit = heard
- thrill = felt
- korotkoff sounds
steps for BP measure?
image
effect of gravity on blood flow?
- gravity maintains blood flow from heart to feet, so when standing = poolung of blood in lower regions of body
- postural hypotension = dizziness upon standing due to pooling of blood in lower so decrease SV= decrease cardiac output resulting in lower bp = transient arterial hypotension
what level is bp readings considered to be at
level of the heart since bp readings changes in respect of their location d to the effect of gravity
