Transport in Animals Flashcards
What are the function of heart strings (tendinius cords)
they prevent AV valves from turning inside out as ventricular pressure increases
Describe the cardiac cycle.
COCO
- left ventricle contracts and pressure in ventricle increases above atrium so AV VALVE CLOSES
- pressure in ventricle increases above aorta so SV VALVE OPENES and blood flows into aorta
- pressure in aorta increases over ventricle so SV VALVE CLOSES
- ventricle relaxes and pressure falls below that of the atrium so AV VALVE OPENES
cycle repeats
what is the equation for cardiac output?
cardiac output (cm3 min-1) = stroke volume(cm3) x heart rate(min-1)
What is the stroke volume?
volume of blood expelled from the left ventricle of the heart per contraction
What is the heart rate?
number if contractions (beats) per minute
Why does the stroke volume increase during exercise?
- the rate which venous blood returns to heart increases
- increased blood flow causes cardiac muscle to contract more strongly
- they pump out an increased volume of blood per beat (high stroke volume)
How does regular exercise reduce resting heart rate?
- heart muscle produces stronger contractions and ventricles become larger in size
- leads to increased stroke volume
What artery and vein does blood leave/enter the kidney
- renal vein
- renal artery
Which veins and artery does blood leave/enter the liver?
- haptic vein
- haptic artery
What is the function of arteries?
carry blood AWAY from heart at high blood pressure
Describe the stretch snd recoil mechanism?
- aorta has a lot of elastic tissue so when the left ventricle contacts the aorta stretches
- when the ventricle relaxes artery wall recoils and forces blood to body tissues
- this provides smooth flow of blood and maintains a relatively high blood pressure when ventricle relaxes
What are some properties of the arteries?
• thicker wall and smaller lumen than veins
• contain more elastic fibres and smooth muscle fibres
• no valves
• transport blood at higher pressure than veins
• carry oxygenated blood
What is the function of atrioles?
- control flow of blood to different tissues/organs by contraction/relaxation of smooth muscles
- they can withstand high pressure in main arteries and
- higher possession if elastic fibres and smooth muscle fibres
What is the function of veins?
Carry blood TOWARDS heart under low pressure
What are some properties of veins
- thinner walls than arteries
- less elastic and smooth muscle fibres that arteries
Why do veins have a larger lumen?
So at low pressures blood flows back to the heart at the same rate that it leaves
How is venous return achieved in veins?
by the contraction of skeletal muscles that surround veins
- when they contract they compress veins and push blood along
Describe the capillaries
- wall is one endothelial cell thick thus short diffuse pathway
-gapsbetween endothelial cell increases permeability
- many capillaries and theyre branches so large surface area for exchange
What gives capillaries a short diffusion pathway?
- no cells are far from a capillary
- red blood cells squeezed against capillary wall
What is the function of blood capillaries?
- supply cells with oxygen, glucose amino etc and remove waste products
How is tissue fluid formed?
• at the arteriole end of a capillary
- high hydrostatic pressure causes filtration of blood plasma
- water, glucose amino etc are forced out the capillary
- large plasma protein remain
- low WP in the capillary, and osmotic pressure smaller than hydrostatic pressure
- so net movement is OUT capillary to form tissue fluid
How is tissue fluid reabsorbed?
• at venule end of capillary
- high frictional resistance due to loss of fluid
- thus low hydrostatic pressure
- large plasma protein remaining in blood maintain a low WP in capillary than tissue fluid
- osmotic pressure is greater than hydrostatic pressure so water is reabsorbed into capillary via osmosis
- remaining tissue fluid enters lymph nodes capillary
- lymph vessels eventually drain in blood
What is heamoglobin?
an iron containing pigment which combines with oxygen to form oxygen haemoglobin
describe haemoglobin’s structure
four haem units and four polypeptide chains (quaternary structure)
