gas exchange and digestion Flashcards
what is the definition for metabolic rate?
amount of energy expended by that organism in a time period
what is the SA:V in a larger organism?
lower
what is the metabolic rate in a larger organism and why?
the metabolic rate is higher
>require more efficient delivery of oxygen
>more respiration needed
>have more advanced exchange surfaces
what does the definition for metabolic demand?
how much oxygen and nutrient an organism needs to take in daily to respire enough to maintain its metabolic rate
what is the SA:V in a smaller organism?
greater
why is the metabolic rate in a smaller organism lower?
as they loose heat more easily
in terms of per unit of body mass, which organism has a higher metabolic rate? why?
smaller organisms
> loose heat more easily so they need more energy
> higher metabolic rate is required
give 2 physical adaptions in a cold environment
- streamline body (smaller SA:V)
- thick fur (insulate to reduce heat loss)
> smaller mammals with higher SA:V
give a behavioural adaptation in a cold environment
- will eat more food/ hibernate (maintain constant temp so they don’t loose heat as easily)
> smaller mammals with higher SA:V
give 2 physical adaptations in a hot/dry environment
- large ears (increase SA to loose heat to maintain constant temp)
> large organisms with lower SA:V - kidney adaptations (produce less urine, less water is lost)
> small organisms with high SA:V
give a behavioural adaptation in a hot/dry environment
- nocturnal (cooler at night)
give the structures of the fish
gills, gill filaments, gill arch, lamella
what do gills increase?
surface area for water to flow over
what is lamella? what does it also contain?
what occurs in the lamella?
lots of tiny folds on the gill filaments.
> contains lots of capillaries and thin layer of cells
- gas exchange occurs (water flows over them)
what is concurrent flow?
where blood and H2O flow over the lamella in the same direction
> large conc gradient between the blood and H2O (diffusion of oxygen to blood occurs)
> conc decreases until equilibrium is reached (diffusion of oxygen to blood stop)
what is countercurrent flow?
where blood and H2O flow over the lamella in the opposite direction
> diffusion occurs throughout the whole lamella as blood always flows alongside H2O
> maintains steep conc gradient across the whole length of gills
why is there large number of capillaries around lamella
removes oxygenated blood to maintain steep conc gradient
what is the function of the operculum?
ventilation. ensure constant fresh water flow over gills to replace lost oxygen
> maintain steep conc gradient
describe the ventilation within a fish
- mouth opens, operculum shuts.
- water enters the cavity due to decreased pressure, increases the volume.
- mouth shuts, operculum opens
- increased pressure, decreased volume.
- increased pressure forces water out over gills.
give the structures in an insect
trachea, tracheoles and spiricoles
why do insects have tracheoles?
increase the surface area for efficient gas exchange
why can spiracles open and close?
to prevent water lost and keeps the organism waterproof
describe the ventilation of a insect
- muscles contract, compressing trachea.
>maintain steep conc gradient to pump gases out and in body - increases pressure, forces air out of spiracles down the pressure gradient
> increase the removal of CO2 when energy demands increase
what do small intestines contain to maximise absorption of nutrient?
villi
what are the features of villi and how does it contribute to the absorption of nutrients?
- one cell thick (to keep diffusion pathway short)
- lots of capillaries (maintain conc gradient, constantly transporting absorbed nutrients around body)
what are epithelial cells?
cells that line the ileum (intestines)
what are the adaptations of epithelial cells? what are the functions of these?
- microvilli (increase SA for diffusion)
- many mitochondria (provide energy for ATP)
- have membrane bound enzymes as monosaccharides are produced close to the ileum (increase absorption rates)
what enzyme does the salivary glands produce?
amylase
what role does amylase play within the digestive system?
hydrolyse glycosidic bonds within amylose and amylopectin (starch) into maltose
what enzyme does the pancreas produce?
pancreatic amylase which is released into the small intestines
>digestive enzymes for absorption
in the ileum there are membrane bound enzymes, what do they digest?
hydrolyse glycosidic bonds in disaccharides into monosaccharides
how is glucose and galactose transported?
uses sodium ions through co transporter proteins
how is fructose transported?
through facillated diffusion using different transporter proteins
where does protein digestion occur?
small intestines and stomach
what acid does the stomach contain, what is its function?
hydrochloric acid
> creates optimum pH (7) for enzyme pepsin to work
how is pepsin secreted?
secreted from other cells that line the stomach
what are the enzymes that digest proteins?
endopeptidases, exopeptidases and dipeptidases
what is the function of endopeptidases?
hydrolyse peptide bonds in large polypeptide chains into smaller polypeptide chains.
>create more terminal ends for exopeptidases (increase SA)
what is the function of exopeptidases?
hydrolyse terminal peptide bonds between amino acid.
>remove individual amino acids and create smaller polypeptide chains (dipeptide)
what is the function of dipeptidases?
hydrolyse peptide bonds in dipeptides
>creates 2 single amino acids to be absorbed
how are amino acid transported?
through active transport with sodium ions
why is endopeptidase important for digestion?
- hydrolyses peptide bond in the middle of large polypeptide chain
- increase number of terminal ends
- more rapid hydrolysis of polypeptide
what are lipases and what is its function?
lipases are digestive enzymes
> hydrolyse ester bonds in triglycerides
where are lipases produced and where is it released?
produced: pancreas
released: small intestines
where are bile salts produced and where is it released?
produced: liver
released: small intestines
what is the function of bile salts?
- help break down large fat globules by emulsifying them into smaller droplets
how does bile salts effect lipase action?
bile salts speed up the action of lipase by increasing SA of lipids to be exposed to lipase
what is a triglyceride a type of?
lipid
what are the products of triglycerides when they are hydrolysed by the lipase?
monoglycerides and fatty acids (non polar molecules)
are fatty acids lipid soluble? if so, why?
yes
- they can diffuse through the plasma membrane which is made phospolipids
>non polar molecules diffuse thorough membrane
>small enough
what do the products from the hydrolysis of a lipid attach to? what do they form?
they attach to bile salts and form micelles
what is the function of micelles?
they help absorption of fatty acids and monoglycerides in bloodstream
how are fatty acids transported?
by the lymphobic system
describe the lymphobic system (how fatty acids are transported)
- micelles hit the epithelial cell and breakdown
–> so monoglyceride + fatty acid can diffuse across membrane - monoglyceride + fatty acid get transported to the ER
–> recombine to form triglycerides again. - triglyceride gets transported to golgi where they bind with cholestrol and proteins
–> packaged to form chylomicrons - chylomicrons travel in a vesicle to cell membrane and exocytosed from epithelial cell.
- chylomicrons enter lymphatic capillaries called lacteals
–> transport away from small intestines to tissues
–> triglycerides can be hydrolysed again to be used by tissues
