intro to VC Flashcards
what vein is blood normally taken from in the arm and what does this do
medial cubital vein
blood traveling to sup vena cava
pressure in vena cava (lying and standing)
lying: 3-8mmHg
standing - 0
composition of blood - fluid and cells
55% fluid
45% cells (mainly RBS)
how much protein is in the blood and in what form
70g/L
mainly albumin
partial pressure of venous gases O2 and CO2
pO2 = 40mmHg (150ml/L) pCO2 = 46mmHg (520ml/L)
what occurs a the Q point on an ECG
depolarisation through AV node (slow)
what does an increased after load do on a frank-starling curve and why
shifts curve down
increased resistance
what effect does increasing activity of cardiac sympathetic nerve fibres have on a frank starling curve and why
shifts up
increase CVP, stretchRV, inc pulmonary pressure, increase LV pressure, stretches and beats more forcefully
increases CO
why is low vascular resistance important for venous system
creates large surface area for gas exchange in alveoli
link poiseuilles law to pulmonary vessels
arteries are shorter and have a larger radius
lower resistance
what’s the pressure in the aorta
120/80mmHg
how much of the SV in the aorta is pushed into smaller arteries (forwards)
25%
75% stored in aorta
how is flow maintained during diastole from the aorta
stored energy in the elastic walls = arterial recoil and pushes blood forwards
what happens to pressure across areas of high resistance
falls steeply
what’s the flow rate
5L/min= CO
what is the microcirculation made out of
terminal arterioles, capillaries, post-capillary venules
diameter of microcirculation
3-10 micron
what controls terminal arterioles and what does it so
- local factors
- controls flow through capillary set
what do capillaries and post-capillary venules lack
no smooth muscle
what is the role of lymphatic capillaries
- absorb fluid and protein and return these to the blood
- take up and transport microorganisms to lymph glands
what are the receptors involved in autonomic regulation of the vascular system, and what branch are they from
- SNS - a1 receptors
- PNS - muscarinic and NANC (non-adrenergic, non-cholinergic e.g. NO)
what circulating hormones regulate vascular system
-adrenaline
angiotensin II (vasoconstriction. increase aldosterone synthesis)
vasopressin (anti-diuretic)
what is atherosclerosis
build up of cholesterol rich plaque
cause stenosis of artery
what can thrombosis lead to if uncreated
unstable angina
myocardial infarction: NSTEMI (v narrow artery) or STEMI (completely blocked)
