3-Exchange Flashcards
What’s the relationship between surface area to volume ratio and exchange
Surface area has to be large compared to the volume for effective exchange
How have larger organisms changed to maintain a large surface area to volume ratio
Flattened, cells aren’t far from surface
Specialised exchange surfaces with large surface area eg lungs
Relationship between surface area to volume ration and metabolic rate
Organisms with a high metabolic rate require alot of exchange and need a large surface area to volume ratio
Adaptations of gas exchange across the body of a single cell organism
Small, large surface area to volume ratio
Thin cell surface membrane
Adaptations of gas exchange surfaces in the tracheal system of an insect
Tracheae, network of tubes supported by strengthened rings
Tracheoles, extend throughout body, short diffusion pathway of air to body cells
Spiracles, pores on surface, can be opened for gas exchange and water evaporation or closed preventing water loss by valve,
Adaptations of gas exchange surfaces across the gills of a fish
Gill filaments, stacked
Gill lamellae, at right angles to filament increasing surface area
Counter current flow, blood and water flow over the gill lamellae in opposing directions, diffusion gradient of oxygen is maintained across width of gill lamellae, oxygen constantly brought to exchange surface
Adaptations of gas exchange surfaces in leaves of dicotyledonous plants
Stomata, small pores, not far from cell, short diffusion pathway,
Mesophyll, interconnecting air spaces, large surface area for rapid diffusion
Structural and functional compromises for efficient gas exchange and limiting water loss in terrestrial insects
Reduce water loss
Small surface area to volume ratio, minimise area where water can be lost
Waterproof covering, water can’t be lost
Spiracles, openings of tracheae can be closed to reduce water loss
An insects body can’t be used for gas exchange , internal network of tubes (tracheae)
Structural and functional compromises to ensure efficient gas exchange and limiting water loss in xerophytic plants
Waterproof covering, a waxy cuticle reduces water loss
Rolled/hairy leaves, traps moist air, no water potential gradient, no water loss
Stomata in grooves, trap moist air, decreases water potential gradient
Reduces surface area to volume ratio, small leaves circular in cross section reduces water loss, balanced against surface area for photosynthesis
Structure of the human gas exchange system
Lungs, pair of lobed structures
Trachea, rings of cartilage and muscle lined with ciliated epithelium and goblet cells
Bronchi, each leads to one lung, produce mucus to trap dirt, become smaller
Bronchioles, branched subdivisions lined by muscle cells to control air flow into alveoli
Alveoli, tiny air sacs, collagen elastic fibres allow stretch when inhaling, gas exchange surface
Features of the alveolar epithelium (gas exchange surface)
Thin, partially permeable, large surface area, maintains a high concentration gradient
What’s ventilation/breathing
Movement of air in and out of the lungs
What’s gas exchange
The diffusion of oxygen into the blood and the diffusion of carbon dioxide out of the blood
What’s happens when inhaling
Active process requiring energy
External intercostal muscles contract internal intercostal muscles relax
Ribs are pulled up and out increasing volume in thorax
Diaphragm muscles contract, flattens increasing volume in thorax also
Atmospheric pressure is greater than pressure in the lungs so air is forced into lungs
What happens when exhaling
Passive process
Internal intercostal muscles contract, external intercostal muscles relax
Ribs move down and in decreasing volume in thorax
Diaphragm muscles relax, pushes up decreasing volume in thorax
Pressure in atmosphere is lower than pressure in lungs so air forces out of lungs
Equation for pulmonary ventilation rate (PVR)
PVR= tidal volume x breathing rate
What happens during digestion
Large biological molecules are hydrolysed into smaller molecules, which can be absorbed across cell membranes
How are carbohydrates in mammals digested
Salivary and pancreatic amylase hydrolyse alternate glycosidic bonds between starch molecules to produce disaccharide called maltose
Membrane bound disaccharidase called maltase, produced by the lining of the ileum hydrolyses maltose into the monosaccharide alpha glucose
How are proteins digested in mammals
Endopeptidase, hydrolyse peptide bond between amino acids in the centre of a peptide, forms smaller peptides
Exopeptidase, hydrolyse peptide bonds on terminal amino acids in a peptide, release dipeptides and single amino acids
Membrane bound dipeptidase, hydrolyse the bond between two amino acids in a dipeptide
How are lipids digested in mammals
Emulsification, lipids are split into tiny droplets, micelles by bile salts produced by the liver, increases surface area of lipids, increased action of lipase
lipase produced in pancreas, hydrolyses ester bond in triglycerides forming fatty acids and monoglycerides
What’s haemoglobin
Haemoglobins are groups of chemically similar molecules found in different organisms
A protein with a quaternary structure
What’s the role of haemoglobin and red blood cells in the transport of oxygen
It readily associates with oxygen at the surface where gas exchange occurs
Readily disassociates from oxygen at tissues needing it
Haemoglobin can change in affinity (chemical attraction) under different conditions
