Intro to CVS Flashcards
why do we need the CVS?
→pump blood through the lungs and carry oxygen
→transport nutrients to the muscles and organs
→circulate hormones and immune mediators
→connection to the lymphatic system
→ human reproduction
→ temperature regulation
what is passive diffusion?
→random, undirected thermal movement of molecules.
what is the equation for passive diffusion?
→ time needed to diffuse a given distance is proportional to the square of the distance: t ∝ d².
what is the main method of molecule movement within the CVS and what does it provide?
→CVS uses convection
→ movement by a pressure gradient
→ It provides fast and directional transport
→diffusion is still crucial for transport over short distances.
what is the significance of having pressure differences?
→output of blood at high pressure creates a pressure difference with distant blood vessels.
→This pressure difference drives blood flow.
where does cardiac output go?
→blood is distributed to various parts of the body, such as the kidneys, liver and GI
what are the brain and myocardium relative to other tissues?
→relatively underperfused.
what controls cardiac output?
→filling pressure (Starling’s Law)
→sympathetic and parasympathetic autonomic nerves
→chemical factors and hormones (eg. adrenaline)
equation for calculating cardiac output?
→Cardiac Output = Heart Rate x Stroke Volume
→CO = HR x SV
why are blood flow and blood pressure important ?
→Blood flow and blood pressure are critical for correct bodily functioning
→ linked in the proper distribution of blood
what happens if there is poor perfusion of the kidney?
→ renal failure and death
equation for calculating blood flow?
→Blood flow = (Pa - Pv)/resistance
→Pa is the pressure at the artery, while Pv is the pressure at the vein.
what is blood flow proportional to and inversely proportional to?
1) proportional to pressure across the blood vessel
2) inversely proportional to the resistance of the blood vessel
why does blood slow down in the capillaries?
→to allow for gaseous/nutrient exchange to occur.
equation for calculating blood velocity?
→Blood velocity (cm/s) = blood flow (cm³/s) / cross-sectional area (cm²)
→To calculate cross-sectional area, we do the number of vessels times the πr² per vessel.
describe in series blood circulation
→same blood supply between organs
→lower perfusion pressures
→medically significant if the first organ is being underperfused
describe parallel blood circulation
→cardiac output is split up
→safeguards O₂ supply in organs
→most organs are supplied this way
what are differences between the structures of arteries and veins?
ARTERIES:
→ thicker elastic wall to maintain blood pressure
→ have high pressure that ensures blood flows in one direction
VEINS:
→thinner elastic walls
→ have valves to ensure no blood backflow
what are elastic vessels?
ELASTIC VESSELS: ARTERIES
what are resistance vessels?
RESISTANCE VESSELS: ARTERIOLES
what are exchange vessels?
EXCHANGE VESSELS: CAPILLARIES
what are capacitance vessels?
CAPACITANCE VESSELS: VENULES AND VEINS
where is most of the blood volume distributed?
→mostly found in large and small veins and venules. →Systemic veins and venules serve as a reservoir, holding about 65% of the volume.
What do large arteries do?
→Large arteries accomodate stroke volume
→convert intermittent ejection into continuous flow
What do resistance vessels do?
→Control arterial blood pressure and regulate local blood flow
What do exchange vessels do?
→Nutrient delivery to cells and tissues for water and lymph formation, and removal of metabolic waste
What do capacitance vessels do?
→Control the filling pressure and provide a reservoir of blood, so the veins can constrict and send blood to the heart if needed
