Topic 8: Exchange & Transport Flashcards
What are the 6 materials that are exchanged in our body?
- Oxygen
- Dissolves food molecules
- Mineral ions
- Water
- Carbon dioxide
- Urea
How to calculate SA:vol ratio?
SA/volume
What SA:vol ratio does a single celled organism have? Why?
Large ratio
SO substances can diffuse in and out at a high rate and easily reach all parts of the cell
What SA:vol ratio does a multicellular organism have? What is the result of this?
Small ratio - many cells are too far away from the outer surface to get substances in and out this way larger
SO they need specialised exchange surfaces where substances can enter and leave the transport system by diffusion e.g. lungs in mammals - these are adapted to increase their surface area to maximise the rate of diffusion
Why are exchange surfaces and transport systems important?
So needs of every cell can be met
What 3 factors affect the rate of diffusion?
Distance - short distance increases rate of diffusion
Concentration gradient - high concentration gradient increases rate of diffusion
Surface area - large surface area increases rate of diffusion
What is Fick’s law?
Rate of diffusion ∝ (surface area x concentration difference) ÷ thickness of membrane
What has to happen to the factors for rate of diffusion to double?
If surface area or difference in concentration doubles
OR
If thickness of membrane halves
Where does gas exchange take place?
In the alveoli (which are in the lungs)
What does the alveoli look like?
Like a ball with a capillary around it
What happens in the alveoli that creates gas exchange?
CO2 goes into the alveoli from the blood cells in the capillary
O2 from the alveoli goes into the blood cells that are in the capillary
What are the adaptations of the alveoli that allow for gas exchange?
- Big surface area - so a large volumes of the gases can diffuse at once
- Thin walls - so there’s a short diffusion distance
- Good blood supply from the capillary - maintains the CO2 and O2 concentration gradients
- Moist lining - so that the gases can dissolve
What are the four components of the blood?
- Red blood cells (erythrocytes)
- White blood cells
- Platelets
- Plasma
What is the function of the red blood cells?
To carry oxygen around the body
Description/adaptations of the red blood cells?
No nucleus - more room for O2
Contains haemoglobin - binds to O2
Biconcave shape - large surface area so lots of O2 absorbed
What is the function of the white blood cells?
Defends against infection
Phagocytes: engulf and destroy pathogens
Lymphocytes: produces antibodies (attacks pathogens)
Description/adaptations of the white blood cells?
Lymphocytes - have antitoxins and antibodies on their surface
Phagocytes - have an opening where the pathogen is engulfed
What is the function of the platelets?
Help the blood to clot at a wound
Description/adaptations of the platelets?
Are made of fragments of cells
What is the function of the plasma?
Carry everything in the blood
Description/adaptations of the plasma?
Liquid that has everything (white blood cells, red blood cells, glucose, O2 etc.)
What are the 3 types of blood vessels?
- Arteries
- Capillaries
- Veins
What do Arteries do?
Carry oxygenated blood AWAY from the heart
What do Capillaries do?
Carry blood Close to body Cells to exchange substances (e.g. alveoli)
What do veins do?
Carry deoxygenated blood back to the heart
Properties of an artery?
Lumen
Thick muscle and elastic layers - blood pressure is high
Properties of a capillary?
Thin, permeable walls - allows substances to diffuse in and out easily
One cell thick, small
Tiny lumen
Properties of a vein?
Largest lumen
Valves inside it - stop backflow of blood
Thinner walls than the arteries - blood pressure is lower
What is the circulatory system made up of?
Heart
Blood vessels
Blood
What type of circulatory system do humans have? Why?
Double circulatory system because there are 2 routes
Route 1 - heart (right ventricle) —> lungs —> heart
Route 2 - heart (left ventricle) —> rest of body —> heart
What is the way to remember the structure of the heart?
RA | LA
————
RV | LV
What blood vessel does the right atrium connect to?
Vena cava (from body)
What blood vessel does the left atrium connect to?
Pulmonary vein (from lungs)
What blood vessel does the right ventricle connect to?
Pumps the blood through the pulmonary artery (to lungs)
What blood vessel does the left ventricle connect to?
Pumps the blood through the aorta (to body)
What does pulmonary link to?
The lungs
What are properties of the left ventricle?
Thicker than the right ventricle - pumps blood at a higher pressure
What do valves do?
Stop back flow of blood
How to calculate cardiac output?
Cardiac output = heart rate x stroke volume
What type of blood does the right side of the heart pump?
Deoxygenated
Pumps it to the lungs to oxygenate it
What type of blood does the left side of the heart pump?
Oxygenated
Pumps blood all around the body
What is respiration?
The constant exothermic process of transferring energy from glucose, in living cells, where the energy transferred is used for metabolic processes
What is aerobic respiration?
Respiration with oxygen - the most efficient type of respiration as transfers the most energy
What is the equation for aerobic respiration?
Glucose + oxygen —> carbon dioxide + water
(Photosynthesis reversed)
What is anaerobic respiration?
Respiration that occurs without oxygen, it produces less energy and so is less efficient
What is the equation for anaerobic respiration in muscle cells?
Glucose —> lactic acid
What is the equation for anaerobic respiration in plant and fungal cells?
Glucose —> ethanol + carbon dioxide
RATE OF RESPIRATION CORE PRACTICAL: What piece of equipment can be used to investigate the effects of temperature on respiration rate?
Respirometer
RATE OF RESPIRATION CORE PRACTICAL: What is the process of this experiment?
- Set up a test tube and a control tube in a water bath
- In the test tube: soda lime granules (absorb CO2 produced by woodlice), live woodlice on a bit of cotton wool, with a syringe (to set level of fluid in manometer) attached to the bung
- In the control tube: soda lime granules (absorb CO2 produced by woodlice), glass beads (same mass as insects) on a bit of cotton wool
- Attach a manometer between the test tubes
- Inside the manometer, the fluid will move towards the woodlice test tube as they use up oxygen during respiration - this can be exactly measured using a calibrated scale
- Repeat with different temperatures
RATE OF RESPIRATION CORE PRACTICAL: What is the conclusion of this experiment?
Faster rate of oxygen consumption shows a faster rate of respiration - shown by to the fluid in the manometer moving further in a given time
Higher temp, higher respiration rate
RATE OF RESPIRATION CORE PRACTICAL: What is the control, independent and dependent variables in this experiment?
Control v: mass of woodlice, volume of liquid in manometer
Independent v: temperature of water in the bath
Dependent v: distance the fluid moves
