1. What is CVD Flashcards
What is a mass flow system?
the transport of substances in the flow of a fluid e.g the circulatory system
Why do animals have a heart and circulatory system?
For mass transport to overcome limitations of diffusion in meeting the requirements of the organism.
Which type of blood enters the right side of the heart?
Deoxygenated
Which type of blood enters the left side of the heart?
Oxygenated
Describe the blood flow sequence through the heart.
vena cava (from body), right atrium, AV valves, right ventricle, semi-lunar valve, pulmonary artery (to lungs) pulmonary vein (from lungs), left atrium, AV valves, left ventricle, semi-lunar valve, aorta (to body)
What is an implication of a faulty heart valve?
leakage
Cardiac muscle contract myogenically. What is meant by myogenic?
The contraction is automatic with no nerve impulse required
Describe the order of the cardiac cycle
Atrial systole, ventricular systole, diastole
Describe atrial systole
Blood under low pressure flows into both atria.
As they fill the pressure on AV valves increases.
Blood forces the valves open and leaks into ventricles.
Atria contract forcing remaining blood out.
Describe ventricular systole
Ventricles contract from the base upwards increasing pressure.
AV valves are forced shut due to the pressure on them to prevent back flow and blood is forced out into the arteries.
Describe diastole
Atria and ventricles relax lowering the pressure in atria and ventricles.
The semi-lunar valves close to prevent back flow
The coronary arteries fill
Low pressure in atria helps draw blood back to the heart.
How is a heartbeat initiated?
SAN/pacemaker (located in the right atrium) starts waves of depolarisation, causing a contraction.
The waves spread and are prevented from reaching ventricles by a band of fibres with high electrical resistance.
The AVN in the septum conducts waves through the ventricles shortly after atria contraction.
The waves are passed onto the purkyne fibres.
The ventricles then contract from the base upwards
Why is waters solvent properties a benefit?
Allow chemicals to dissolve easily so biochemical reactions can occur in the cytoplasm
Why do ionic molecules dissolve easily in water?
When broken apart the ions are attracted to the oppositely charged water molecule part
Polar molecules that also easily dissolve in water are said to be..
hydrophillic
Name a non-polar, hydrophobic substance.
Lipids
Why is waters high SHC a benefit for organisms?
It warms up and cools down slowly so organisms can maintain a steady temperature even when the ambient temperature is constantly changing
Describe and explain the structure of an artery.
Narrow lumen
thick walls- withstand pressure
middle coat with lots of collagen and elastic tissue- for elastic recoil to minimise damage
no valves
Describe and explain the structure of a vein.
wide lumen
thinner walls
less collagen and elastic tissue
valves- pressure is low so prevents back flow
What is assisted flow in the veins?
Pressure in the veins is low so the flow is helped by the contraction of skeletal muscles.
Describe and explain the structure of a capillary.
One cell thick cell walls to allow for easy diffusion.
Blood pressure is low to assist with diffusion
no valves
