| why do animals have a heart and circulatory system? | to pump blood around the body so that oxygen can diffuse into cells for respiration |
| features of a mass transport system | network of blood vessels to move through
blood as the medium of movement
controlled direction and speed by the heart |
| why is a mass transport system important? | Overcomes the limitation of diffusion in larger organisms
transports substances around the body
allows the exchange of substances to occur |
| properties of water | dipolar molecule
contains hydrogen bonds
high specific heat
cohesive
good solvent |
| why is water dipolar? | water has a permanent dipole
oxygen atom is more electronegative than hydrogen atoms |
| why is the polarity of water important? | allows other polar molecules and ions to dissolve in water |
| what is specific heat capacity? | the amount of heat required to increase the temperature of 1 gram of matter by 1 degree celsius |
| why is water's high heat capacity important? | helps organisms to maintain a constant temperature which is essential for vital process that occur in the body |
| why is water cohesive and why is it important? | strong attraction between water molecules due to its dipolar nature allows it to flow and transport susbstances |
| why is water a good solvent? | water is polar so polar molecules and ions can dissolve in it |
| what are the blood vessels? | arteries, veins, capillaries
transport blood around the body |
| function of arteries | carry oxygenated blood away from the heart and to the body tissues (except the pulmonary artery) |
| structure of arteries | small lumen
smooth inner endothelial lining
thick layer of smooth muscle cells
thick layer of elastic fibre
lots of collagen |
| functions of veins | carry deoxygenated blood from the body to the heart (except the pulmonary vein) |
| structure of veins | wide lumen
inner endothelium lining
thinner layer of smooth muscle cells and elastic fibres
less collagen
valves |
| how is the structure of capillaries related to its function? | as it is one cell thick it allows for the easy metabolic exchange of substances |
| what is the function of the endothelium in blood vessels? | the smooth passage of blood through arteries and veins
short diffusion distance in capillaries |
| what is the function of the smooth muscle cells? | expand and contract to dilate and constrict the lumen which regulates blood pressure |
| what is the function of elastic fibres in blood vessels? | stretch and recoil to maintain blood pressure |
| what is the function of collagen in blood vessels? | to withstand the high blood pressure generated in the blood vessels
provides structural support to the vessels |
| what is the function of valves? | prevents the backflow of blood
they only open one way
if pressure is higher behind the valve it opens and if pressure is higher in front of the valve it is closed |
| features of the heart | vena cava
left and right atria
left and right atrioventricular valves
left and right ventricles
left and right semi lunar valves
pulmonary artery
pulmonary vein
aorta
coronary arteries
septum
cardiac muscle (made of cardiac cells) |
| what processes are involved in the cardiac cycle? | atrial systole
ventricular systole
diastole |
| what does the heart do? | the muscle at the centre of the circulatory system that pumps blood around the body |
| what happens during atrial systole? | the atria contract
AV valves are open and SL valves closed
pressure in atria increases
blood is pushed into the ventricles |
| what happens during ventricular systole? | ventricles contract
AV valves closed, SL valves open
pressure in ventricles increases
blood is pushed up into the pulmonary artery (right) and aorta (left) |
| what happens during diastole? | heart is relaxed
AV valves open
pressure in atria begins to increase |
| how many chambers does the heart have? | 4
2 atria and 2 ventricles |
| what does each side of the heart do? | the right side pumps deoxygenated blood to the lungs
the left side pumps oxygenated blood to the body |
| why does the left side have more cardiac muscle than the right side? | on the left side blood has a longer distance to travel therefore needs to generate higher pressure so that the oxygenated blood can reach all the cells |
| why is the septum important? | it divides the left and right sides
it prevents the mixing of oxygenated and deoxygenated blood
it maintains the concentration gradient of the blood in each side allowing for efficient gas exchange and diffusion |
