3.2 transport in animals Flashcards
Define tachycardia
heart beats too fast
Define bradycardia
heart beats too slow
Define ectopic
heart skips a beat or extra beat is added
Define fibrilliation
heart contracts at an irregular way
Define systole
ventricles are contracted
Define diastole
ventricles are relaxed
What is the tunica intima made up of in an artery
endothelial layer, connective tissue layer, elastic fibres
Function of the tunica intima in the artery
reduce friction
What is the tunica media made out of in the artery
elastic lamellae, connective tissue, smooth muscle
Why is the tunica media layer thick in the artery
- withstand high pressures
- contract and narrow lumen for reduced blood flow
Function of elastic tissues in the tunica media in the artery
recoil and change blood pressures
What is the tunica adventita made out of in the artery
collagen
Function of collagen in the tunica adventita in the artery
protects blood vessels from over stretching
Function of a larger lumen in a vein
- ensures blood returns to the heart
- reduces friction between the blood and endothelial layer
- more volume of blood carried
Why is the tunic media poorly developed
do not need to withstand high pressures
Where is the bicuspid valve found
between the left atrium and left ventricle
Where is the tricuspid valve found
between the right atrium and right ventricle
Where is the aortic valve found
between the left ventricle and aorta
Where is the pulmonary valve found
between the right ventricle and pulmonary valve
What happens during atrial systole
- the walls of the atria contract
- atrial volume decreases = artial pressure increases
- pressure in the atria rises above the ventricles forcing the AV valve open
- blood moves into the ventricles
What happens during ventricular systole
- walls of the ventricles contract
- ventricular volume decreases = ventricular pressure increases
- pressure in the ventricles rises above artia
- AV valves close
- pressure in the ventricles rises above the aorta and pulmonary artery
- SL valves open so blood is forced out
What happens during diastole
- both the atria and ventricles are relaxed
- pressure in the ventricles drop below aorta and pulmonary artery so SL valves close
- atria fills with blood
- pressure rises in the atria and the AV valves open
- cycle is repeated
Cardiac output
heart rate x stroke volume
Define myogenic
heart beats without any help of an external stimulus
What does the SAN do
initiates a wave of depolarisation that causes the atria to contract
What does the AVN do
causes a delay so the ventricles contract after the atria
What do the purkyne fibres do
initiate depolarisation of the ventricles from the apex (bottom)
What is the P wave on an electrocardiogram
causes by the depolarisation of the atria, resulting in atrial systole
What is the QRS complex on an electrocardiogram
causes by the depolarisation of the ventricles, resulting in ventricular systole
What is the T wave on an electrocardiogram
causes by the repolarisation of the ventricles, resulting in ventricular diastole
What happens when oxygen binds to haemoglobin
forms oxyhaemoglobin
What is cooperative binding
when an oxygen molecule can bind more easily to the iron in the haem group
How are hydrogen carbonate ions formed
- carbon dioxide diffuses into the erythrocyte to combine with water
- red blood cells contain carbonic anhydrase - catalyses a reaction between carbon dioxide and water to form carbonic acid
- this readily disassociates into hydrogen (H+) and biocarbonate ions (HCO3-)
- biocarbonate ions are pumped out of the cell in exchnage with chlorine ions
What is the purpose of haemoglobin in the carriage of carbon dioxide
act as a buffer
What do H+ ions do in the carriage of carbon dioxide
- bind to haemolgobin to form haemoglobinc acid (prevents H+ ions changing the pH of the erythrocyte)
What happens in the chloride shift
- hydrogen carbonate ions are moved out from the red blood cell via a transport protein in the membrane
- negatively charged chloride ions are transported into the red blood cells (prevent electrical inbalance)
What does a shift to the left on a carriage of oxygen graph mean
increased affinity of oxygen
What does a shift to the right mean on a carriage of oxygen graph
decreased affinity of oxygen
Define affinity
strength of which two molecules bind to each other
When is haemoglobin considered saturated
when all four of its binding sites are taken up with oxygen
Process of oxygen association to haemoglobin
- due to the shape of the haemoglobin molecule it is difficult for the first molecule to bind therefore it takes longer
- the first oxygen changes the shape so it is easier for the next oxygen to bind
- as it approaches saturation it takes longer as there is a shortage of binding sites
Why does foetal haemoglobin have a higher affinity
- the placenta has a low pO2 so the mothers haemoglobin dissociates quicker
- higher affinity means the foetus can pick up the oxygen at lower pO2
Define hydrostatic pressure
pressure exerted by a fluid
Define oncotic pressure
osmotic pressure exerted by plasma proteins within a blood vessel
What happens at the ateriole end of the capillary
- hydrostatic pressure is greater than the oncotic pressure so fluid is forced out
What happens at the venule end of a capillary
- hydrostatic pressure is lower than the oncotic pressure so fluid is forced into the blood
Define odema
when too much fluid is pushed outside so it accumlates around the capillary
What does the lymphatic system do
maintains correct pressure gradient for the movement of tissue fluid
