3.1.2 transport in animals NOT ON MOCK Flashcards
Why do multicellular organisms require transport systems
They are large so have a small surface area to volume ratio and therefore have high metabolic rates. And the demand for oxygen is high, so need a specialised system to ensure a strong supply to all respiring tissues
Summarise the different types of circulatory systems
Open: blood can diffuse out of vessels e.g. insects
Close to: blood confined to vessels e.g. fish, mammals
Single: blood passes through pump once per circuit of the body
Double: blood passes through heart twice per circuit of the body
Relate the structure of arteries to their function
thick, muscular walls to handle high-pressure without tearing. Elastic tissue allows recoil to prevent pressure surges and narrow lumen to maintain pressure
Relate the structure of veins to their function
Thin walls due to lower pressure. Valves to prevent back flow of blood. Have less muscular and elastic tissue as they don’t have to control blood flow
Relate the structure of capillaries to their function
Was only one cell thick so they have a short diffusion pathway, very narrow so can permit tissues and red blood cells can lie flat against the wall, effectively delivering oxygen to tissues, also highly branched which means they have a large surface area
Relate the structure of arterioles and venules to their function
They branch off arteries and veins in order to feed blood into capillaries. They are smaller than arteries and veins so that the change in pressure is more gradual
What is tissue fluid
A watery substance containing glucose, amino acids, oxygen and other nutrients. It’s supplies these to the cells, while also removing any waste materials
What types of pressure influence formation of tissue fluid
hydrostatic pressure: higher at arterial end of capillary than Venous end
Oncotic pressure: changing water potential of the capillaries as water moves out, induced by proteins in the plasma
how is tissue fluid formed
As blood is pumped through increasingly small vessels, hydrostatic pressure is greater than oncotic pressure, so fluid moves out of the capillaries. It then exchanges substances with the cells
How does tissue fluid differ from blood and lymph
Tissue fluid is formed from blood, but does not contain red blood cells, platelets and other various solutes usually present in blood. It contains less oxygen, nutrients and more products
Describe what happens during cardiac diastole
The heart is relaxed. Blood enters the atria, increasing the pressure and pushing open the atrioventricular valves. This allows blood to flow into the ventricles. Pressure in the heart is lower than in the arteries, so semilunar valves remain closed
Describe what happens during atrial systole
The atria contract, pushing any remaining blood into the ventricles
Describe what happens during ventricular systole
The ventricles contract. Pressure increases, close in the atrioventricular valves to prevent back flow and opening the semilunar valves. Blood flows into the arteries
How do you calculate cardiac output
Cardiac output is heart rate multiplied by stroke volume
What does myogenic mean
The hearts contraction is initiated from within the muscle its self, rather than by nerve impulses
Explain how the heart contracts
SAN Initiates and spreads impulse across the atria, so they contract. AVN Receives, delays and then conveys the impulse down the bundle of his. Impulse travels into the purkinye Fibres which branch across the ventricles so they contract from the bottom up
Describe types of abnormal activity that may be seen on an ECG
tachycardia: fast heartbeat
bradycardia: slow heartbeat
fibrillation : irregular, fast heartbeat
ectopic: early or extra heartbeats
Describe the role of haemoglobin
Present in red blood cells. Oxygen molecules bind to the haem groups and are carried around the body, then released where they are needed in respiring tissues
How does partial pressure of oxygen affect oxygen haemoglobin binding
As partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin. When partial pressure is low, oxygen is released from haemoglobin
What do oxyhaemoglobin dissociation curve show
Saturation of haemoglobin with oxygen ( in percentage), plotted against partial pressure of oxygen in kilopascals. Curves further to the left show the haemoglobin has a higher affinity for oxygen
describe the bohr effect
As partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape. The affinity of haemoglobin for oxygen therefore decreases, so oxygen is released from haemoglobin
Explain the role of carbonic anhydrase in the Bohr effect
Carbonic anhydrase is present in red blood cells. Convert carbon dioxide to carbonic acid, which dissociate to produce H + ions. these combine with a haemoglobin to form haemoglobinic acid. Encourages oxygen to dissociate from haemoglobin
Explain the role of bicarbonate ions in gas exchange
Produced alongside carbonic acid. In the lungs, carbonate ions are converted back to carbon dioxide which we breathe out
Describe the chloride shift
The intake of chloride ions across a red blood cells membrane. This repolarises the cell after bicarbonate ions have diffused out
How does fetal haemoglobin differ from adult haemoglobin
The partial pressure of oxygen is low by the time it reaches the fetus, therefore fetal haemoglobin has a higher affinity for oxygen then adult
ppq: Why is the delay between excitation of atria and ventricles essential
To allow time for the atria to fully contract/empty and the ventricles to fill so that ventricles don’t contract to early
ppq: the purkyne tissue carries the Excitation wave down the septum to the apex of the heart. Explain why the excitation wave is carried to the apex
So that ventricular contraction starts at the apex, the bottom, to push blood upwards
ppq: Describe and explain what happens to the blood plasma along the capillary
Plasma moves out of the capillary and forms tissue fluid. Plasma proteins remain in the capillary as they are too large to pass through capillary wall. The fluid moves down pressure gradient and hydrogen pressure is greater than water potential
ppq: Describe how the action of the heart is initiated and coordinated
SAN Initiates excitation which spreads over atrial wall . Atrial systole Occurs and contraction is synchronised. There is a delay at AVN and excitation spreads down septum. Ventricular systole occurs from apex
ppq: What is the name given to a trade show in the electrical activity of the
Electro cardiogram
ppq: State to affects of digitalis on the activity of the heart
Heart rate is slower, diastole Longer, ventricle takes longer to contract
ppq: describe the roles of SAN AND AVN In coordinating the cardiac cycle
SAN initiates heart beat and sends impulse over atria. AVN delays impulse and sends impulse down the septum
ppq: How is hydrostatic pressure generated in the heart
Contraction of ventricle wall ventricular systole
ppq: Explain why the hydrostatic pressure of the blood drops as blood moves away from the heart
There are more smaller vessels that have larger total surface area which reduces resistance to bloodflow as artery stretch and loss of plasma from capillaries
ppq: Explain why it is important that the pressure changes as blood flows from the aorta to the capillaries
The capillary walls are thin and high-pressure would damage the capillary wall
ppq: Suggest two advantages of keeping the blood inside vessels
It maintains high blood pressure and blood moves quicker
ppq: Explain how pressure changes in the heart bring about the closure of the atrioventricular valve bicuspid
Tissue requires more oxygen for aerobic respiration and it produces more carbon dioxide. less haemoglobin available to combine of oxygen as involved in transport in carbon dioxide so bohr shift cause more oxygen to be released
ppq: describe and explain how substances That are dissolved in the blood plasma into the tissue fluid from the capillaries
They enter by diffusion from an area of high concentration to low. Hydrostatic pressure in the capillary is higher than in tissue fluid and is more permeable and the fluid is forced out of the capillary
ppq: Which to circulatory system is best described mammalian blood circulatory system
Close and double circulatory system
ppq:Explain what causes the pressure to fluctuate as the blood flows along the aorta
systole Increases pressure, diastole decrease his pressure and ventricular systole increases pressure
ppq: Explain why the fetal haemoglobin curve is to the left of the adult haemoglobin curve
The placenta has low partial pressure of oxygen an adult haemoglobin will release oxygen in the presenter. So fetal haemoglobin picks up more oxygen an adult as it has a high affinity for oxygen even when little is available
ppq: State one difference between fetal haemoglobin an adult and give a reason why this difference is essential to the fetus
Fetal haemoglobin has a higher affinity for oxygen and this is essential because the fetal haemoglobin must be able to bind to oxygen in lower partial pressure in the placenta when the adult Oxy haemoglobin dissociates
ppq:Explain why tissue fluid does not contain erythrocytes
The gaps are too small and erythrocytes are too large to fit between the gaps
ppq:Describe the role of haemoglobin in transporting oxygen around the body
Haemoglobin has a high affinity for oxygen and the oxygen binds to haemoglobin in the lungs to make Oxy haemoglobin. Oxygen is then released in tissues when needed
ppq: List the events that occurred during the cardiac cycle
Atrial walls start to relax, ventricle walls start to contract, S a node generates electrical signals, walls of atria contract, AV node receive electrical signals from SA node, electrical signals transmitted down septum, ventricle walls start to contract, AV valves close, ventricle walls relax, semilunar valves close
ppq: Describe how the hydrogen carbonate ions are produced in the erythrocytes
Carbon dioxide enters into the white blood cells and combined with water to create carbonic anhydrase which catalyses and convert carbon dioxide to carbonic acid, which dissociates to produce H plus ions.
ppq: Name the effect that high concentrations of carbon dioxide in the blood reduce the amount of oxygen transport to buy haemoglobin, and explain why occurs
bohr effect and it occurs to reduce the affinity of haemoglobin for oxygen and alter the shape of haemoglobin
