B7.2 Flashcards
definition of the circulatory system
system of tubes (veins, capillaries, arteries) with a pump (the heart) and valves to ensure one way flow of blood
what does double circulatory system mean
blood passes through the heart twice while completing a cycle around a body
what two parts does the double circulatory system consist of
pulmonary circulation and systemic circulation
what is pulmonary circulation
when the heart pumps blood into the lungs, the blood becomes oxygenated and flows back to the heart
what is systemic circulation
the oxygenated blood returning to the heart is then pumped to the rest of the body
how many chambers are there in a double circulatory system
four chambers
how many chambers are there in a single circulatory system
two chambers
what animal is the single circulatory system applied to?
fish
how does single circulatory system work in fish?
blood absorbs the oxygen in fish gills, then it is released in body cells then back to the heart
what are the advantages of double circulatory system over single circulatory system?
- the heart gives pressure to the lungs twice to ensure it reaches the body tissues after it comes back from the lungs –> this allows greater blood flow rate which is much more efficient for metabolically active organs of the body which need oxygen to be delivered quickly
name all the structures of the right side of the heart in the order of blood flow
vena cava, right atrium, triscuspid valve, right ventricle, semi-lunar valve, pulmonary artery
name all the structures of the left side of the heart in the order of blood flow
pulmonary veins, left atrium, bicuspid valve, left ventricle, semi-lunar valve, aorta
what is the function of right atrium
collects deoxygenated blood and pumps it into the right ventricle
what is the function of right ventricle
pumps deoxygenated blood to the lungs
what is the function of triscuspid and bicuspid valve
prevents backflow of blood into the atria when ventricles contract
what is the function of pulmonary artery
carries deoxygenated blood from the right ventricles to the lungs
what is the function of pulmonary veins
carries oxygenated blood from the lungs to the left atrium
what is the function of left atrium
collects oxygenated blood and pumps it into the left ventricle
what is the function of left ventricle
pumps oxygenated blood to the body via the aorta
what is the function of semi-lunar valve
prevents backflow of blood from the arteries to the ventricles
what is the function of aorta
carries oxygenated blood from left ventricle to the rest of the body
what is the septum
a structure that separates the left and right sides of the heart –> makes sure that oxygenated and deoxygenated blood keeps separate
describe the flow of blood in the heart (structures)
- deoxygenated blood enters the heart through the vena cava into the right atrium
- right atrium contracts and blood moves through triscuspid valve into the right ventricle
- the right ventricle contracts and blood exits the heart through semilunar valve into the lungs through the pulmonary artery
- blood becomes oxygenated in the lungs and returns back to the heart through the pulmonary vein and enters left atrium
- left atrium contracts and blood moves through bicuspid valve into the left ventricle
- left ventricle contracts and oxygenated blood exits the heart past the semilunar valve through the aorta and travels around the body, becoming deoxygenated
how is the left ventricle adapted differently to the right side
the wall of the left ventricle is thicker than the right ventricle
why is the wall of the left ventricle thicker than the right ventricle?
so that it can pump blood at a high pressure around the entire body rather than just to the lungs
why are the walls of the ventricles thicker than the walls of the arteries?
arteries only have to pump blood to the ventricles lying below it whilst the ventricles have to pump blood at high pressure to the whole body
why are triscuspid and bicuspid valves not present in arteries?
the pressure in the arteries is high enough that backflow doesn’t occur
how are oxygenated and deoxygenated blood usually delivered to/away from the heart
deoxygenated blood travels in veins to the heart
oxygenated blood travels in arteries away from the heart
how is pulmonary artery, vein different to the usual way oxygenated and deoxygenated blood is delivered
pulmonary artery carries deoxygenated blood from the heart to the lungs
pulmonary veins carries oxygenated blood from the lungs to the heart
define heart rate
measure of how frequently the heart beats (bpm)
how is each pulse of blood created
by one contraction of the ventricles
name the factors in which the resting heart rate may vary
age - children have a faster average than adults
fitness - trained athlete may have low resting rate because their heart contains more muscle and can pump out more blood with each contraction
illness - infection can increase resting rate but some diseases can slow resting heart rate
diet - diets high in salt and caffeine will raise heart rate
why does heart rate increase during activity?
during physical activities, muscles respire to produce energy for movement. Aerobic respiration requires oxygen so the heart needs to pump oxygen around the body quickly which speeds up the heart rate
what are coronary arteries?
branches from the aorta at the point the aorta leaves the heart supply blood to the muscles of the heart
why do hearts require special arteries?
the heart is full of blood, the muscles are so thick and highly active that they need these special arteries to constantly supply them with nutrient and oxygen
how does a heart attack happen?
cardiac muscles depend on the coronary arteries for the supply of nutrients and oxygen
if the coronary arteries get blocked, the cardiac muscles don’t have enough energy for contraction
this damages the heart muscles due to loss of blood supply
what can result from a heart attack?
cardiac arrest - when heart stops beating
what is the main cause of heart attacks?
coronary heart disease
what can cause a blockage in the coronary arteries in coronary heart disease?
build-up of cholesterol and fatty deposits (plaques) in the coronary arteries
how does the build up of plaques in the coronary arteries cause coronary heart disease?
the plaques reduce the diameter of coronary arteries that blood can travel through.
Before heart attack, one of the plaques burst, causing blood clot
the clot completely blocks the artery , cutting the blood supply to part of the heart muscle
name factors that cause CHD
smoking, diet, diabetes, obesity, lifestyle, genes
why does smoking cause CHD
chemicals (nicotine) in tobacco smoke that pass into the blood damage the lining of the arteries
how can diet cause CHD
diet rich in animal fat and salt and cholesterol increases the chance of getting CHD
what are genes that can cause CHD
older age
men have greater risks
african americans have greater risks
describe plasma (functions, what it is)
plasma is mostly water but with many substances dissolved in it (protein, glucose, amino acids)
plasma carries hormones, carbon dioxide , material to be excreted
what is the function of red blood cell
deliver oxygen to tissues in the body
how is a red blood cell adapted to perform its function
- biconcave shape –> increases surface area, allows higher rate of diffusion of oxygen
- don’t have nucleus –> more space for transporting oxygen
- haemoglobin –> proteins that transport oxygen
what is the function of white blood cell
part of the immune system that responds to infection by trying to kill the pathogen
what is phagocytosis?
type of white blood cell that kills pathogens by flowing around it until it is completely enclosed
what is the function of platelets
protects humans from infection by forming blood clots when there is damage to blood vessel
name three different types of blood vessels
arteries, capillaries, veins
describe features, functions, structure of arteries
large blood vessels
carry blood at high pressure which is flowing away from the heart
thick muscular and elastic walls, narrow central space (lumen) through which the blood flows
why do arteries have thick muscle layer
to control the volume of blood by constricting the artery
describe features, functions, structure of veins
large blood vessels (thinner than arteries)
carry blood at low pressure
thin elastic wall and muscle layer
has a large lumen through which blood flows
valves in these veins prevents backflow of blood
describe features, functions, structure of capillaries
tiny blood vessels that exchange substances with tissues such as oxygen, nutrients
carry blood at low pressure in both directions which links the arteries and veins
how are capillaries adapted to perform its function
thin permeable walls consisting of single layer of cells –> reduces distance for diffusion to occur, increases efficiency of exchange
narrow lumen –> allows capillaries to fit into small spaces throughout the body’s tissues
