topic 8 - exchange and transport in animals

describe the need to transport oxygen into organisms

• oxygen is transported INTO organisms

• by diffusion

• for cells to complete aerobic respiration

describe the need to transport carbon dioxide out of organisms

• carbon dioxide is transported OUT OF organisms

• by diffusion

• as it is a waste product of aerobic respiration

describe the need to transport water into organisms

• water is transported into organisms

• by osmosis

• for osmoregulation

• for cell and bodily reactions to occur

describe the need to transport dissolved food molecules into organisms

• multicellular organism take in food by eating

• food is broken down in the digestive system

• dissolved food molecules are transferred INTO the bloodstream at the small intestine

• by diffusion

• dissolved food molecules in the bloodstream can be transported to all the cells in the body

• for cell reactions

describe the need to transport mineral ions into organisms

• mineral ions are absorbed into the organism

• by active transport

• for the activation of enzymes and membrane function

describe the need to transport urea out of organisms

• urea is a waste product of the liver

• it is toxic to the body

• it is transported to the kidneys by the circulatory system

• it is ultra filtrated by the blood and ends up in the bladder as urine

state which sub-cellular structure exchange of substances occurs in

cell surface membrane

state the 3 types of transport processes

• diffusion

• osmosis

• active transport

which types of organism has a very large surface area : volume ratio

unicellular organisms

what does a large surface area : volume ratio mean

• surface of the organism

• to the centre

• is very small

what does the large surface area : volume ratio of unicellular organisms mean

• they do not need to have specialist exchange surfaces

• or transport systems

• as diffusion, osmosis and active transport through the cell membrane occur

• at a sufficient rate

• to meet the needs of the organism

what’s the relative size of the surface area : volume ratio of multicellular organisms

small

state the transport systems in animals

blood and circulatory system

state the transport systems in plants

• xylem

• phloem

state the function of xylem

• moves water and mineral ions

• from the roots

• to shoots and leaves

state the function of phloem

• moves sugars and amino acids

• to where they are needed

• in the plant

state the function of the circulatory system

• blood carries

  • oxygen

  • glucose

  • carbon dioxide

  • water

  • waste around the body

state why multicellular organisms need exchange surfaces

• they have a small surface area : volume ratio

• so exchange surfaces are needed

• in order to carry out

• diffusion, osmosis and active transport

• at a sufficient rate

state exchange surfaces in animals

• lungs and alveoli - gas exchange

• small intestines and villi - absorption of digested food

state exchange surfaces in plants

• roots and root hairs - mineral ions and water are absorbed

• leaves - gas exchange

state how multicellular organisms maximise the exchange of materials

• have large surface areas

• very thin barriers to separate 2 regions

state why having a large surface area maximises the exchange of materials

increase the rate of transport

state why having very thin barriers to separate 2 regions maximises the exchange of materials

provides as short a diffusion path as possible

state how multicellular organisms maximise the exchange of materials

• have large surface areas

• very thin barriers to separate 2 regions

• large network of blood vessels throughout the body

• ventilates gas exchange surfaces

state why having a large network of blood vessels maximises the exchange of materials

• reduces the distance of exchange of materials between cells and the bloodstream

• moves substances towards or away from exchange surfaces to maintain concentration gradients

state why having ventilated gas exchange surfaces maximises the exchange of materials

maintains concentration gradients

explain how the lungs are adapted for gas exchange by diffusion

• the lungs are the gas exchange surface in the humans

• the lungs contain many rounded alveolar sacs

• which act to increase the surface area : volume ratio of the lungs

• to increase the rate of gas exchange

explain how the alveoli are adapted for gas exchange by diffusion

• thin single layers of cells

  • to minimise diffusion distance

• ventilated

  • maintains high levels of oxygen and low levels of carbon dioxide in the alveolar air space

• good blood supply

  • ensures constant supply of blood high in carbon dioxide and low in oxygen

• layer of moisture on alveolar surface

  • helps diffusion as it causes gases to dissolve

explain how surface area affects the rate of diffusion

• a bigger cell or structure has a smaller surface area : volume ratio

• which slows down the rate at which substances can move across its surface

• thus increasing surface area : volume ratio increases the rate of diffusion

state which cells are adapted to increase surface area

• root hair cells in plants

• cells lining the ileum in animals

explain how concentration gradient affects the rate of diffusion

• larger concentration gradient on either side of the membrane

• causes faster movement across it

• this is because on the side with the higher concentration

• more random collisions will occur against the membrane

explain how diffusion distance affects the rate of diffusion

smaller diffusion distance causes faster transport to occur

state which structures are adapted to have smaller diffusion distance

• walls of

• blood capillaries and alveoli

• are only one cell thick

• to ensure faster rate of diffusion

explain how temperature affects the rate of diffusion

• higher temperature means the molecules move faster

• as they have gained more kinetic energy

• this results in more collision of molecules against the cell membrane

• causing a faster rate of movement/spreading across them

state Fick’s law equation

rate of diffusion ∝ (surface area x concentration difference) / thickness of membrane

explain how the structure of erythrocytes are related to its function

• STRUCTURE

  • biconcave discs

  • contain no nucleus

  • contain lots of haemoglobin protein

• FUNCTION

  • erythrocytes are specialised cells that carry oxygen to respiring cells

  • the haemoglobin binds to oxygen to form oxyhaemoglobin

  • having no nucleus allows more space for more haemoglobin protein

  • the biconcave disc shape gives erythrocytes a large surface area : volume ratio - maximises diffusion of oxygen in and out

state what erythrocytes are

red blood cells

explain how the structure of lymphocytes are related to their function

• STRUCTURE

  • large cells

  • contain a big nucleus

  • highly specific structures

  • clear, non-granular cytoplasm

• FUNCTION

  • lymphocytes are part of the body’s immune system to defend against pathogenic microorganisms

  • they produce antibodies to destroy pathogenic cells

  • they produce antitoxins to neutralise toxins released by pathogens

  • clear, non-granular cytoplasm allows for lymphocytes to be easily identified using a microscope

explain how the structure of phagocytes are related to their function

• STRUCTURE

  • large cells

  • contain a big, multi-lobed nucleus

  • highly specific structures

  • granular cytoplasm

• FUNCTION

  • carry out phagocytosis by engulfing and digesting pathogens

  • phagocytes have sensitive cell surface membranes that detect chemicals produced by pathogenic cells

  • release digestive enzymes when encountering a pathogen

  • their multi-lobed nucleus and granular cytoplasm makes them easy to distinguish using a microscope

state what lymphocytes and phagocytes are

white blood cells

explain how the structure of plasma is related to its function

• STRUCTURE

  • straw coloured liquid

• FUNCTION

  • suspends the other components of blood within it

  • transports carbon dioxide

    • carbon dioxide is dissolved in plasma to form hydrogen carbonate ions

    • these ions are transported from respiring cells to the lungs

  • transports digested food and mineral ions

    • dissolved food molecules absorbed from the small intestine are delivered to the requiring cells around the body by plasma

  • transports urea

    • urea is the waste substance produced in the breakdown of proteins into amino acids by the liver

    • urea is dissolved in the plasma and transported to the kidneys where it exits the body through the bladder

  • transports hormones

    • hormones are released into the plasma from the endocrine organs

    • they’re delivered to target tissues/organs in the body

  • transports heat energy

    • heat energy is synthesised in respiration

    • where it is transferred in plasma to cooler parts of the body or skin

    • where the heat can be dissipated

explain how the structure of platelets is related to its function

• STRUCTURE

  • fragments of cells

• FUNCTION

  • when the skin is broken, platelets arrive to stop the bleeding

  • a series of reaction occur within the plasma

  • platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin

  • which forms an insoluble mesh across the wound

  • this traps red blood cells at the wound site, forming a clot

  • this clot eventually dries and develops into a scab which protects the wound from bacteria enetering

explain why blood clotting is important

• prevents continued/significant blood loss from wounds

• scab formation prevents entry of pathogenic microorganisms

• remains in place to allow new skin to grow unharmed

state the 3 types of blood vessel

• arteries

  • arterioles - small arteries that branch into venules

• veins

  • venules - small veins

• capillaries

explain how the structure of arteries are adapted to their function

• STRUCTURE

  • thick, muscular walls containing elastic fibres

  • narrow lumen

• FUNCTION

  • carries blood at high pressure and rapid speed away from the heart

    • thick, muscular walls allow the artery to withstand and maintain the high blood pressure as it recoils after the blood has passed through

    • narrow lumen helps to maintain high blood pressure

  • carries oxygenated blood (except the pulmonary artery)

explain how the structure of veins are adapted to their function

• STRUCTURE

  • thin walls

  • large lumen

  • contain valve

• FUNCTION

  • carries blood at low pressure towards the heart

    • large lumen reduces resistance to blood flow under low pressure

    • valves prevent backflow of blood as it is under low pressure

  • carries deoxygenated blood (except the pulmonary vein)

explain how the structure of capillaries are adapted to their function

• STRUCTURE

  • thin walls - one cell thick

  • ‘leaky’ walls

• FUNCTION

  • carries blood at low pressure within tissues

    • capillaries walls are thin and ‘leaky’ to allow substances to easily diffuse in and out of them

    • ‘leaky’ walls allows blood plasma to leak out and form tissue fluid surrounding cells

  • carries both oxygenated and deoxygenated blood

  • carries blood at low speed

explain how the structure of heart is related to its function

• STRUCTURE

  • double pump

  • 2 ventricles

  • septum

  • coronary arteries

  • cardiac muscle tissue

  • valves

• FUNCTION

  • oxygenated blood enters from the left side of the heart and is pumped to the rest of the body

    • left ventricle has a thicker muscle wall than the right ventricle as it pumps blood at high pressure around the entire body

  • deoxygenated blood enters from the right side of the heart and is pumped to the lungs

    • right ventricle has a thinner muscle wall than the left ventricle as it pumps blood at low pressure to the lungs

  • septum separates the two sides of the heart to prevent the mixing of oxygenated and deoxygenated blood

  • coronary arteries supply the cardiac muscle tissues of the heart with oxygenated blood

    • this happens as the heart is a muscle that needs a constant supply of oxygen and glucose for aerobic respiration to allow for continued muscle contraction

  • valves prevent blood flowing backwards

describe the pathway of blood through the heart

• deoxygenated blood coming from the body flows through the vena cava into the right atrium

• the atrium contracts, forcing the blood through the tricuspid valve into the right ventricle

• the right ventricle contracts to push blood through the semilunar valve into the pulmonary artery

• blood travels to the lungs and moves through capillaries past the alveoli where gas exchange takes place

  • low blood pressure on the right side of the heart prevents damage to the pulmonary capillaries

• oxygenated blood returns to the heart via the pulmonary vein to the left atrium

• the atrium contracts and forces the blood through bicuspid valve into the left ventricle

• the left ventricle contracts and blood is forced through the semilunar value and out through the aorta

  • thicker muscles walls of the left ventricle produce a high enough blood pressure to allow the blood to travel through the whole body

describe the circulatory system

• circulatory system consists of closed network of blood vessels connected to the heart

• oxygenated blood is carried away from the heart and towards organs in arteries

• arteries narrow to arterioles and then further to capillaries as they pass through organs

• in the organs, the respiring cells use up the oxygen bound to haemoglobin on red blood cells

• the capillaries then widen to venules then further to veins as they move away from organs

• veins carry deoxygenated blood back towards the heart

state the function of lymphatic vessels

• network of vessels

• that collects all excessive tissue fluid

• that leaks out the ‘leaky’ capillary walls

• and delivers this fluid back to the circulatory system

state the blood vessels that direct blood TOWARDS the HEART

• vena cava

• pulmonary vein

state the blood vessels that direct blood TOWARDS the LUNGS

pulmonary artery

state the blood vessels that direct blood TOWARDS the KIDNEY

renal artery

state the blood vessels that direct blood AWAY FROM the HEART

• aorta

• pulmonary artery

state the blood vessels that direct blood AWAY FROM the LUNGS

pulmonary vein

state the blood vessels that direct blood AWAY FROM the KIDNEYS

renal vein

describe cellular respiration

• exothermic reaction

• that occurs continuously

• in living cells

• to release energy

• for metabolic processes

describe the process of aerobic respiration

• aerobic respiration requires oxygen

• it is the complete breakdown of glucose

• to release a relatively large amount of energy

• for use in cell processes and reactions

• carbon dioxide and water are produced as waste products

state aerobic respiration definition

• chemical reaction in cells

• that uses oxygen

• to break down nutrient molecules

• to release energy

describe the process of anaerobic respiration

• anaerobic respiration doesn’t require oxygen

• it involves the incomplete breakdown of glucose

• so it releases a relatively small amount of energy

• to use in cell processes

• different breakdown products are formed based on the organism

state anaerobic respiration definition

• chemical reaction in cells

• that breaks down

• nutrient molecules

• to release energy

• without oxygen

describe anaerobic respiration in animals

• anaerobic respiration takes place in muscle cells during vigorous exercise

• during vigorous exercise, animal muscles have a higher demand for energy

• when oxygen runs out for aerobic respiration, glucose is broken down without it

• producing lactic acid instead

• glucose has not been fully broken down meaning there is still energy stored within the bonds of lactic acid molecules

• anaerobic respiration releases less energy than aerobic respiration

state the word and symbol equation for anaerobic respiration in animals

describe lactic acid and oxygen debt

• lactic acid builds up in muscles cells and lowers the pH of muscle tissues

  • acidic conditions can denature the enzymes in cells

• lactic acid will eventually be metabolised using oxygen to produce carbon dioxide and water as waste products

• the amount of energy required to metabolise the lactic acid is ‘oxygen debt’

• the process of metabolising the lactic acid is ‘repaying the oxygen debt’

describe anaerobic respiration in plants and fungi

• plants and yeast can respire without oxygen

• breaking down glucose in the the absence of oxygen

• to produce ethanol and carbon dioxide

• anaerobic respiration in yeast cells is fermentation

state the symbol equation for anaerobic respiration in fungi

describe the method to investigate the production of carbon dioxide in respiration

1. measure out 10cm³ of hydrogen carbonate indicator into 3 boiling tubes

2. put a layer of cotton wool into each boiling tube

3. place 10 germinating seeds in tube A

4. place 10 dead seeds in tube B

5. place 10 glass beads in tube C

6. seal each tube with a rubber bung

7. after 3 hours, observe the colour of the indicator

8. tube A should turn yellow as the seeds are respiring and producing carbon dioxide

9. tube B should remain orange as the dead seeds produce no carbon dioxide

10. tube C should remain orange as there is no living material in the tube

state the results of hydrogen carbonate indicator

• low carbon dioxide levels - purple

• atmospheric carbon dioxide levels - orange

• high carbon dioxide levels - yellow

describe the method to investigate the production of heat in respiration

1. set up 2 flasks, one containing dead seeds, one containing germinating seeds

2. ensure the cotton wool is plugging the top of each flask

3. hold the thermometer in place with the cotton wool

4. invert the flasks

5. record the initial temperature of both flasks

6. after 4 days, record the final temperature

7. the thermometer in the flask with the germinating seeds should show an increase in temperature

   1. because the seeds in this flask are respiring and producing heat energy in the process

   2. showing that respiration is an exothermic reaction

8. the flask with the dead seeds should remain at room temperature

   1. because the seeds are not respiring as they were dead, meaning temperature will remain the same as the exothermic reaction isn’t occurring

state the equation for cardiac output

cardiac output = stroke volume x heart rate

state the width of a whole capillary

only 5-10 micrometres

state what a constant flow of blood in the capillary does to concentration gradients between capillaries and cells

maintains a steep concentration gradient

stroke volume definition

volume of blood pushed out of a ventricle into an artery

cardiac output definition

volume of blood pushed into the aorta per minute

heart rate definition

number of beats per minute

state what factors cause cardiac output to change

• exercise

• fight or flight

• anticipating exercise