Cardiovascular 1 Flashcards
What are the 2 circulatory systems?
Pulmonary and systemic
What is the role of the pulmonary system?
supplies lungs with deoxygenated blood via pulmonary arteries
What is the role of the lungs?
oxygenates blood and removes CO2
What is the role of the pulmonary vein?
Receives oxygenated blood from left side of heart
What is the role of the left Side of the heart?
pumps oxygenated blood into aorta and around body via several parallel circuits
Where does deoxygenated blood from the body go to?
returns to right side of heart via vena cava
List all the types of vessels?
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
List the structures of artery wall
what do the arteries do?
carry blood form the heart and they’re thick walled and elastic
what can we feel when feeling the pulse?
you can feel the stretching of the vessel wall with each heart contraction
what happens when the arteries relax between each beat ?
can cause the stored blood to continue to flow between each heart beat
Describe the capillaries ?
- highly branched
- thin walled
- increase SA of gas electrolyte exchange between tissues and blood
what do w have between the capillaries ?
arterioles (baby arteries)
role of arterioles ?
can constrict or dilate to control blood flow to a specific tissue
where does blood flow from capillaries ?
venules and then to the thin walled, highly compliant veins (pressure gradient)
what is the pressure like once blood reaches the veins ?
very low ( the heart doesn’t suck blood towards it as this would collapse the thin walled veins )
what do veins have that prevent back flow?
valves
What are the 4 things that can contribute to blood flow back to the heart via venous return?
1) intermittent contraction of skeletal muscles eg. leg muscles
2) increases and decreases in thoracic pressure when we breath
3) the diaphragm compressing the abdominal veins with each breath
4) increase in blood in veins as we get closer to heart as more blood has returned from the tissue via the venues
heart anatomy
List the different valves?
- tricuspid
- mitral
- pulmonary
- aortic
what are the atrioventricular valves ?
- tricuspid
- mitral
where do the anterioventricular valves sit between?
between an atrium and an ventricle
where does the tricuspid valve sit between?
between RA and RV
where does the mitral valve sit between?
between LA and LV
Where does the pulmonary valve sit between?
pulmonary artery and RV
where does the aortic valve sit between ?
Aorta and LV
What specialised structures do valves have to stop backwards blood flow?
little papillary muscles that contract to prevent valves opening in wrong direction
what is systole?
heart contraction
what is diastole?
heart relaxation
what happens during diastole? (3)
- AV valves are open ( tricuspid and mitral)
- aortic/ pulmonary valves closed
- blood flows from atria to ventricles
what happens during systole? (7)
1) atria contract which pushes last bits of blood into the ventricles from the atria
2) this causes higher pressure in ventricles than the atria and therefore closes T and M valves
3) papillary muscles contract to prevent these valves closing too far or opening in other direction
4) atria refill with blood from VC and PV
5) ventricles contract which further increases ventricular pressure and pushes aortic and pulmonary valve open
6) once pressure in arteries increase enough and pressure is higher than in ventricles this pushes aortic and pulmonary valves closed again and ventricles relax
7) the pressure in ventricles thus become lower than the atrial pressure which pushes the AV valve open = now in diastole
simplified version of systole
what is the Frank Starling Mechanism?
- heart adapts such that it can always pump the blood that is returned to it by the venous onwards
- the greater it is stretched, the stronger it contracts (upto a point due to intrinsic properties of the cardiac muscle cells and the overlap of myosin and actin)
what controls the relaxation and contractions of the heart muscle to cause diastole and systole?
electrical activity that spreads between muscle cells
where does electrical conductivity start?
SAN (in the RA)
what happens In the SAN?
the cells have an intrinsic timer that causes ion permeability
what does ion permeability cause in SAN?
the sinus node creates a depolarisation that spreads across the atria to the AVN
what is the annulus fibrosis?
a non conductive fibrous tissue found In the AVN
what does the depolarisation need in order to progress to the ventricles
needs to pass through AVN due to non conductive fibrous tissue called annulus fibrosis
what does the AVN do?
slows the spread of current and then propagates it between the ventricles via the bundle of his and then to the purkinje fibres
where is the bundle of his located?
between the ventricles
what happens when the atria are depolarised ?
they contract
why is the delay in the AVN important ?
allows for the contraction of the atria to have time to fill the ventricles before they in turn are depolarised contract and push blood around the body
how do we measure the flow of current around the heart?
ECG by using electrodes
what do electrodes do?
detects the direction and amount of current flowing thru the heart
what is a 12 lead ECG?
provides 12 (planes of direction) directional views of electricity across the heart