organisms exchange substances with their environment Flashcards
what surface area: volume do small organisms have?
-large surface area: volume, to allow efficient exchange across the body surface
what surface area: volume do large organisms have?
-small surface area: volume, to allow efficient exchange across the body surface
how do you calculate the surface area and volume?
surface area=
-area of one side x amount of sides
volume=
-length x width x height
what are the features of specialised exchange surfaces? (3)
-large surface area: volume, which increases the rate of exchange
-very thin, providing a short diffusion pathway
-selectively permeable, allows selected materials to cross
how does anaerobic respiration increase gas exchange in insects?
- anaerobic respiration in muscles produce lactate
- lactate in the muscles decrease water potential
- water moves from the tracheoles into the muscle by osmosis
- this decreases the volume of tracheoles
- this draws air into the tracheoles, therefore increasing gas exchange
what are the structures in insects relating to gas exchange? (3)
tracheoles=
-thin, providing a short diffusion pathway
-highly branched, large surface area
exoskeleton=
-prevents water loss
spiracles=
-hairs, preventing water loss
-holes on the surface that can open and close, preventing water loss
-allows oxygen to diffuse into tracheae
what are the three ways gases move in and out the tracheal system in insects?
-along a diffusion gradient
-mass transport
-ends of the tracheoles are filled with water
what are the structures of the gills in fish relating to gas exchange?
gill filaments=
-contain gill lamellae
gill lamellae=
-many of them, large surface area
-very thin, providing a short diffusion pathway
what is counter current flow?
-flow of water over the gill lamellae and the flow of blood travel in opposite directions
-diffusion gradient is maintained throughout the whole gill filament
-if they both flowed in the same direction, far less gas exchange would take place
what is the counter current exchange principle?
-blood that is already loaded with oxygen meets water, which has its maximum concentration of oxygen
-therefore diffusion of oxygen from the water to the blood takes place
-blood with little oxygen in it meets water, which has had most of its oxygen removed
-therefore diffusion of oxygen from the water to the blood takes place
what are three plant adaptations that allow for rapid diffusion?
- small pores called stomata, that are not far from the stoma
-short diffusion pathway - numerous interconnecting air spaces in the mesophyll
-gases can readily come in contact with mesophyll cells - large surface area of mesophyll cells
-rapid diffusion
what are three insect adaptations that reduce water loss?
- small surface area: volume ratio
- waterproof coverings (exoskeleton)
- spiracles (openings of the trachea)
what are five plant adaptations that reduce water loss?
- thick cuticle
- rolling up of leaves
- hairy leaves
- stomata in pits or grooves
- reduced surface area: volume ratio of the leaves
what happens when breathing in (inspiration) in humans?
-ribs move outwards
-exterior intercostal muscle contracts, interior intercostal muscle relaxes
-diaphragm flattens by contracting
-thorax volume increases, therefore pressure in the thoracic cavity decreases
-pressure in the thoracic cavity is lower than the atmospheric pressure
what happens when breathing out (expiration) in humans?
-ribs move inwards
-interior intercostal muscle contracts, exterior intercostal muscle relaxes
-diaphragm pushes up the lungs by relaxing
-thorax volume decreases, therefore pressure in the thoracic cavity increases
-pressure in the thoracic cavity is higher than the atmosphere pressure
what are the structures in the respiratory system?
lungs=
-made up of a series of bronchioles, which end in tiny air sacs called alveoli
trachea=
-flexible airway supported by rings of cartilage
bronchi=
-two divisions of the trachea, each leading to one lung
bronchioles=
-series of branching subdivisions of the bronchi
alveoli
-air sacs at the end of bronchioles
what are the alveoli adaptations in gas exchange?
surrounded by collagen and elastic fibres=
-provides structure and elasticity to the lungs
many of them=
-provides a large surface area
one cell thick=
-short diffusion pathway
surrounded by a large capillary network=
-oxygenated blood can be transported away quickly
capillary’s are very narrow=
-short diffusion pathway
red blood cells are flattened=
-slows them down for more diffusion
what are the structures in the digestive system?
oesophagus=
-carries food from the mouth to the stomach
stomach=
-stores and digests food, especially proteins
small intestine=
-food is further digested by enzymes
large intestine=
-absorbs water
rectum=
-stores faeces before passed into the anus
what are the two types of digestion?
physical=
-teeth
-stomach churns food
-peristalsis in the oesophagus
chemical=
-hydrolyses large, insoluble molecules through enzymes
what happens in the carbohydrate digestion of starch?
enzyme=
-amylase
where is amylase produced=
-salivary glands
-pancreas
bond breaking=
-glycosidic bond
product=
-maltose
what happens in the carbohydrate digestion of maltose?
enzyme=
-maltase
where is maltase produced=
-lining of the ileum (small intestine)
bond breaking=
-glycosidic bond
product=
-alpha glucose
what happens in the carbohydrate digestion of sucrose?
enzyme=
-sucrase
where is sucrase produced=
-small intestine
bond breaking=
-glycosidic bond
product=
-glucose
-fructose
what happens in the carbohydrate digestion of lactose?
enzyme=
-lactase
where is lactase produced=
-small intestine
bond breaking=
-glycosidic bond
product=
-glucose
-galactose
what happens in the lipid digestion?
enzyme=
-lipase
where is lipase produced=
-pancreas
bond breaking=
-ester bond
product=
-glycerol
-fatty acids
what happens in the protein digestion?
enzyme=
-peptidases (umbrella term)
where are peptidases produced=
-pancreas (endo & exo)
-small intestine (exo)
-stomach (endo)
-membrane bound in the ileum (di)
bond breaking=
-peptide bond
product=
-amino acids
what is exopeptidase?
-hydrolyses terminal amino acids (at the end)
what is endopeptidase?
-hydrolyses central peptide bonds
what is dipeptidase?
-hydrolyses dipeptides into amino acids
what is the structure and function of the villi in digestion? (5)
large surface area in small intestine=
-maximises diffusion
thin walls=
-short diffusion pathway
many mitochondria=
-ATP for active transport
muscles=
-moves food
good blood supply=
-transports molecules
what is the absorption of lipids process?
- bile salts emulsify lipids into micelles
- micelles come into contact with epithelial cells in the ileum, they are then broken down into monoglycerides and fatty acids
- these are small and non polar so diffuse across the cell surface membrane
- triglycerides reform in the endoplasmic recticulum and then move into the golgi, where chylomicrons are formed
- chylomicrons move out of the epithelial cells by exocytosis and enter lymphatic capillaries called lacteals
what is the order of the blood flow around the heart?
-deoxygenated blood, vena, cava, right atrium, right ventricle, pulmonary artery, lungs
-becomes oxygenated at the lungs, pulmonary vein, left atrium, bicuspid valve, left ventricle, aorta, body
what are the two types of valves in the heart?
semi-lunar valves=
-in the aorta and pulmonary artery
-prevent backflow of blood into the ventricles when pressure exceeds
atrioventricular valves=
-between atrium and ventricle on both sides
-prevent backflow of blood when contraction of ventricles means ventricular pressure exceeds atrial pressure
-left atrioventricular (bicuspid)
-right atrioventricular (tricuspid)
what is systole and diastole?
systole=
-period of contraction
diastole=
-period of relaxation
-normally lasts longer
what is the cardiac cycle?
-sequence of events repeated by humans around 70 times each minute when at rest
-consists of three stages: atrial and ventricular diastole, ventricular systole and atrial systole
what happens in atrial and ventricular diastole?
relaxation of the heart=
-low blood pressure in heart, blood moves into atria
-AV valves initially closed
-as the atria fill, pressure rises and AV valves open allowing blood to pass into the ventricles
-semi lunar valves close to stop back flow from the aorta
what happens in atrial systole?
contraction of atria=
-atria are filled with blood (high pressure)
-atria both contract, AV valves open
-blood is pushed into the ventricle
-semi lunar valves are closed
what happens in ventricular systole?
contraction of ventricle=
-slight delay to allow ventricles to fill with blood
-ventricle walls contract, increasing the blood pressure within them
-AV valves close preventing backflow of blood into atria
-semi lunar valves open
what are the types of blood vessels?
-arteries, veins, capillaries, arterioles, venules
what is the blood pressure of the blood vessels?
arteries=
high
arterioles=
-lower than arteries
capillaries=
-low
veins=
-low
what is the muscle layer size of the blood vessels?
arteries=
-thick
arterioles=
-thicker than arteries
veins=
-thick
what is the elastic layer size of the blood vessels?
arteries=
-thick
arterioles=
-thinner than arteries
veins=
-thick
what is the overall wall diameter of the blood vessels?
arteries=
-thick
arterioles=
-thick
capillaries=
-thin
veins=
-thin
what is the lumen size of the blood vessels?
arteries=
-thin
arterioles=
-thinner than arteries
capillaries=
-thin
veins=
-thick
what is hydrostatic pressure?
-pressure created by a fluid pushing against the container that it’s within
what is tissue fluid?
-liquid that surrounds cells
-provides: oxygen, amino acids, glucose, ions and fatty acids
what is the tissue fluid formation?
arterial end of the capillary=
1. high hydrostatic pressure
2. plasma and small molecules pushed out into the tissue fluid
3. large molecules (cells and protein) remain in the blood, called ultrafiltration
4. returning fluid goes back into the capillary
venous end of the capillary=
1. low hydrostatic pressure due to water lost to tissue fluid
2. water is forced back into the capillaries due to hydrostatic gradient
3. low water potential in capillaries so water moves back in via osmosis
-some water moves into the lymphatic system, that then drains back into the bloodstream
what is the process of transpiration?
-loss of water vapour through the leaves of plants
1. lower water potential in the atmosphere compared to inside the leaf’s air spaces
-water evaporates out the stomata
2. now a low water potential in air spaces, so water evaporates from the mesophyll cell walls into air spaces
3. water moves from xylem to mesophyll cells (high to low concentration)
-this creates cohesion, tension of water molecules (transpiration pull)
what is the process of translocation?
-process by which organic molecules and mineral ions are transported from one part of a plant to another
at source cells=
1. sucrose is produced in a photosynthetic cell
2. sucrose moves into companion cell by facilitated diffusion
3. sucrose moves into the sieve cell by active transport
4. high sucrose at the top of the phloem, therefore low water potential
-water moves into phloem from xylem by osmosis
-high hydrostatic pressure
at sink cells=
1. decrease of sucrose as it is either stored or used
2. sucrose moves from companion cell into sink cell by diffusion, therefore low water potential
-water moves by osmosis out of the phloem
-decreased hydrostatic pressure
what is the structure and function of sieve and companion cells? (phloem)
sieve cells=
-hollow/few organelles, easier flow of substances
-thick/strong walls, resist pressure
companion cells=
-many mitochondria, site of respiration/ATP
-many ribosomes, site of protein synthesis
what is haemoglobin?
-quaternary protein
-made up of 4 polypeptide chains
-4 oxygen molecules can bind to 1 haemoglobin molecule
-Fe+
what is associating and disassociating?
associating=
-binding of oxygen to haemoglobin
disassociating=
-unbinding of oxygen to haemoglobin
what is affinity (high or low)?
-chemical attraction
what is the role of haemoglobin?
-transport oxygen
-at the lungs, haemoglobin has a high affinity for oxygen (high association)
-at the tissue, haemoglobin has a low affinity for oxygen (high disassociation)
what can oxygen-haemoglobin dissociation curves tell us?
-start at low oxygen saturation at the tissue, where there is a low affinity for oxygen and low partial pressure
-difficult for first oxygen to bind
-after first oxygen binds, quaternary structure of haemoglobin changes and next oxygen binds much easily
-curve starts to increase until it levels off, where 4th oxygen is harder to bind as there is a low probability for it to find the empty slot on the haemoglobin molecule
-at 100% oxygen saturation at the lungs, there is a high affinity and high partial pressure
