transport in animals

Question 1

what is single circulation

Answer 1

when blood passes through the heart one time, eg in fish

Question 2

what is double circulation

Answer 2

when blood passes through the heart twice eg in mammals

Question 3

what si the structure and functin of arteries

Answer 3

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

Question 4

what is the structure and functions of veins

Answer 4

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

Question 5

what are venules

Answer 5

venules are small blood vessels which collect blood leaving the capillaries, these lead tot he veins

Question 6

what are arterioles

Answer 6

when arteries reach an organ they split into smaller vessels, they can constrict and allow blood to flow

Question 7

how are the capillaries adapted for effective transport of oxygen

Answer 7

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

Question 8

what is tissue fluid

Answer 8

it is a combination of oxygen water and nutrients, it allows substances to be transported into the cells

Question 9

what is pressure filtration

Answer 9

when substances move into the tissue fluid from the capillaries

Question 10

what is a network of capillaries called

Answer 10

a capillary bed

Question 11

right artium

Answer 11

de-oxygenated blood flows in via the vena cava

Question 12

right ventricle

Answer 12

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

Question 13

left atrium

Answer 13

oxygenated blood from the lungs enters the left atrium from the pulmonary vein

Question 14

left ventricle

Answer 14

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

Question 15

where are the walls of the heart the thickest

Answer 15

the left ventricle

Question 16

what are the easiest blood vessels to identify when dissecting the heart

Answer 16

the conorary artery and the aorta

Question 17

what are the stages of the cardiac cycle

Answer 17

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

Question 18

what causes the heart to beat

Answer 18

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

Question 19

what does the p wave represent

Answer 19

it represents the depolarisation as the impulse passes from the SAN to the AVN

Question 20

what is the QRS complex

Answer 20

represents the depolarisation of the ventricles as the impulse passes from the bundle of his and the perkiji fibres

Question 21

what does the t wave represent

Answer 21

the repolarisation of the ventricles

Question 22

what does the pause on the ecg show

Answer 22

the impulse is held at the AVN before it moves down the bundle of his to depolarise the ventricles

Question 23

what makes an abnormal ecg trace

Answer 23

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

Question 24

what does affinity mean in the context of haemoglobin

Answer 24

it is attracted to oxygen, when red blood cells reach the lungs, oxygen binds to haemoglobin, this forms oxyhaemoglobin

Question 25

what is partial pressure

Answer 25

the concentration of an element in a cell

Question 26

when the partial pressure of oxygen is high what happens to the affinity of haemoglobin to oxygen

Answer 26

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

Question 27

what is the chloride shift

Answer 27

chloride ions move into the haemoglobin to reduce the amount of bicarbonate ions in the cell, this maintains the cells neutrality