transport in animals Flashcards
what is single circulation
when blood passes through the heart one time, eg in fish
what is double circulation
when blood passes through the heart twice eg in mammals
what si the structure and functin of arteries
arteries transport blood away from the heart around the body, they have thick walls to be able to maintain high pressure, they have elastic fibres which allow the arteries to stretch
what is the structure and functions of veins
the veins transport blood from the body to the heart, the lumen of the veins are larger than the arteries which allow the blood to flow at a low pressure, they also have valves which prevent back-flow of blood
what are venules
venules are small blood vessels which collect blood leaving the capillaries, these lead tot he veins
what are arterioles
when arteries reach an organ they split into smaller vessels, they can constrict and allow blood to flow
how are the capillaries adapted for effective transport of oxygen
they have a large surface area which means that gas exchange is more efficient, the walls of the capilaries are one cell thick this means that there is a short diffusion pathway
what is tissue fluid
it is a combination of oxygen water and nutrients, it allows substances to be transported into the cells
what is pressure filtration
when substances move into the tissue fluid from the capillaries
what is a network of capillaries called
a capillary bed
right artium
de-oxygenated blood flows in via the vena cava
right ventricle
when the walls contract in the right atrium, deoxygenated blood flows into the right ventricle, atrio-ventricular valves prevent back-flow, the walls of the right ventricle contract and then blood is pumped out of the heart via the pulmonary artery, the semi-lunar valves prevent backflow
left atrium
oxygenated blood from the lungs enters the left atrium from the pulmonary vein
left ventricle
when the walls of the left atrium contract the oxygenated blood flows in through the bicuspid valve, when the left ventricle contracts the blood leaves the heart via the aorta at a high pressure
where are the walls of the heart the thickest
the left ventricle
what are the easiest blood vessels to identify when dissecting the heart
the conorary artery and the aorta
what are the stages of the cardiac cycle
atrial contraction-blood flows from the left atrium and blood from the body flows into the right atrium, when the atria contract blood is forced into the ventricles, as the ventricles are relaxed they fill with blood
ventricular contraction-the atria relax and the ventricles start to contract, this causes the pressure inside of the ventricles to increase, the pressure shuts the AV valves so there is no back-flow, the blood is forced out of the ventricles through the pulmonary artery and aorta
relaxation-blood flows back into the ventricles and atria
what causes the heart to beat
The SAN is in the right atrium, it acts as the pacemaker and transmits waves along the walls of the atria at regular intervals, the electrical waves cause the right and left atrium
to contract, this forces blood into the ventricles, the electrical activity passes through the AVN to the bundle of his, the electrical energy passes to the perkinji fibres, as the waves pass through the perkiji fibres, the ventricles contract together and the blood is forced out of the heart
what does the p wave represent
it represents the depolarisation as the impulse passes from the SAN to the AVN
what is the QRS complex
represents the depolarisation of the ventricles as the impulse passes from the bundle of his and the perkiji fibres
what does the t wave represent
the repolarisation of the ventricles
what does the pause on the ecg show
the impulse is held at the AVN before it moves down the bundle of his to depolarise the ventricles
what makes an abnormal ecg trace
the frequence of the PQRST cycly shows the heart rate, this can show if a persons heart rate is too high or too low, it will also show irregular heartbeats
what does affinity mean in the context of haemoglobin
it is attracted to oxygen, when red blood cells reach the lungs, oxygen binds to haemoglobin, this forms oxyhaemoglobin
what is partial pressure
the concentration of an element in a cell
when the partial pressure of oxygen is high what happens to the affinity of haemoglobin to oxygen
when the partial pressure of oxygen is high then haemoglobin has a high affinity so it will more easily bind to the haemoglobin, if the partial pressure is low then it will have a low affinity for oxygen and therefore dissociate
what is the chloride shift
chloride ions move into the haemoglobin to reduce the amount of bicarbonate ions in the cell, this maintains the cells neutrality
