Overview of CVS function Flashcards
What does MAP stand for?
Mean Arterial Pressure
What does CVP stand for?
Central Venous Pressure
The cVS is a ……… flow system
bulk
What does the CVS move around?
CO2, O2, nutrients, waste, metabolites, immune cells, hormones, heat
Right and Left side of heart are in parallel/series? What does that mean about the output of the R/L side? What would happed if there was a problem with this?
In parallel. This means that the output on the R side must equal the output on the L side, otherwise blood will either pool in the pulmonary circulation or the systemic circulation.
Vascular beds in series/parallel? What are the advantages of this?
In parallel, means that each section of the body receives freshly oxygenated blood, also able to redistribute the proportion of blood that goes to each part of the body, eg more to legs when exercising.
Which vascular beds are in series and why?
Gut and liver, because there are a lot of nutrients that come from the gut that are passed onto the liver. The liver also has it’s own extra blood supply via portal system.
Total CO at rest?
5L
What % to brain? Heart? Skeletal muscle? Skin? Kidney? Abdominal organs? Other? Why to these places?
13%, 4%, 20%, 9%, 20%, 24%, 10%. Generally to match the oxygen requirements of the organs/tissues.
Why does the kidneys receive 20% blood but only have 6% oxygen requirement?
Because it is the kidneys job to filter out the blood so to do its job well needs blood flowing through it!
(Dracy’s law) Flow = ?
Change in pressure/ resistance
Pressure difference =
Mean Arterial Pressure (MAP) - Central venous pressure (CVP)
Which vessels dilate/constrict to vascular beds? What are they also known as?
The arterioles. They are also known as resistance vessels (as they can change their resistance)
What is capaticance? Capacitance vessels?
Capacitance is the ability of a vessel to hold blood. The veins are good at this and so they are known as capacitance vessels.
What is the fractional distrrubution of blood?
The percentage of total blood in the body that is in the veins vs the arteries. The amount within the veins can change (eg decrease whilst doing exercise). by constricting or dilating venules/veins to expel some of the capacitance of blood they contain towards the heart.
What are the 2 elastic arteries? What is an elastic artery features?
The Aorta and Pulmonary Trunk
V wide lumen (low resistance), thick wall cont. lots of elastin and therefore is elastic. - imp. to dampen down the pressure variations from the heart.
What type of vessels are arteries? Why?
Muscular arteries - wide lumen, strong (muscular) non-elastic wall to maintain pressure - low resistance conduit (pipes)
What type of vessels are the arterioles? How are they differentiated?
Ressistance vessles. Differentiated by their narrow lumen. Still have thick muscular wall which can control resistance and therefore flow, allowing regional redirection of blood.
What are the exchange vessels called, how thick are the walls? What are the advantages?
Capillaries. Walls are v thin (1 cell thick, 1 layer of endothelial cells) to allow diffusion of substances across, and big surface area to volume ratio.
Features if venules/veins, what are they also known as?
Capacitamce vessels, wide lumen, walls are collapsible and dispensable. 2 functions: Low resistance conduit to get blood back to the heart, and reservoir for blood (capacitance)
What does the septum do?
Divides the left and right sides of the heart
What is the myocardium? Which side is thicker?
The heart muscle (wall of the heart)
What does the pulmonary trunk leave from?
Right ventricle
Valves : leaving left ventricle
Aortic valve (! - enters the aorta)
Leaving right ventricle
Pulmonary valve (shock horror - enters the pulmonary trunk)
What are aortic and pulmonary valves also known as?
Semi-lunar valves
What valve between atrium and ventricles?
On right side (right atrium to right ventricle) = Tricuspid valve (3 cusps)
On left side(left atrium to left ventricle) = Mitral valve (2 cusps)
What makes the valves open/shut?
Passive pressure of blood moving.
What is the purpose of the Chordae Tendinae and papillary muscle?
The Chordae Tendinae is the tendon preventing the valves (tricuspid and mitral) from inverting), the papillary muscle is contracting when the heart contracts as the heart gets smaller to ensure that the chordae tendinae are prevented from inverting even on contraction of the heart.
What is standard stroke volume?
75ml/beat
What is standard CO?
5L/min
Where in the body shows Alpha 1 receptors/B2 receptors for sympathetic innervation?
Every artery has alpha 1 receptors (causing arteriolar constriction) , but the cardiac and skeletal muscle also have many more Beta 2 receptors which swamp the response to constrict by their repsons to dilate
In the injury response, what does it depend upon?
The injury response depends on action potentials invading the terminals of nociceptive C-fibres and triggering the release of substance P - which causes arteriolar dilation.
What contributes to the pace maker potential?
Gradual closing of the leaky K+ channels and opening of the “funny” Na+ channels and T-type Ca2+ channels.
