Topic 4) Gas exchange and transport

Elisa de Toro Arias
Mind Map by Elisa de Toro Arias, updated more than 1 year ago
Elisa de Toro Arias
Created by Elisa de Toro Arias about 4 years ago


AS - Level A Level – Biology Mind Map on Topic 4) Gas exchange and transport, created by Elisa de Toro Arias on 04/05/2016.

Resource summary

Topic 4) Gas exchange and transport
1 4. 1 – Surface area to volume ratio
1.1 Smaller, single-celled organisms
1.1.1 Surface area : volume = large Surface area in contact with outside is very large, in comparison to volume inside organism Big surface area where diffusion can occur
1.2 Bigger, multi-cellular organisms
1.2.1 Surface area : volume = smaller Increased distance between outside and inside of organism Substances do not diffuse to cells fast enough Need specialised gas exchange (eg. lungs) + mass transport system (eg. circulatory system)
1.2.2 Higher metabolic rate
1.3 Determines whether diffusion alone will allow substances to move in and out of cells
2 4.2 – Cell transport mechanisms
2.1 Fluid mosaic model of cell membrane
2.1.1 Lipoprotein bilayer Mosaic = scattered proteins Fluid = lipids + proteins able to move past each other in linear plane
2.1.2 COMPONENTS Carbohydrate polymers Glycolipids when attached to phospholipids Glycoproteins when attached to proteins Enzymes Attached to membrane → carry out metabolic reactions Cholesterol molecules Disturbs the close-packing of the phospholipids → increasing flexibility of membrane Proteins TYPES Integral proteins Partially or totally buried within lipid bilayer Peripheral proteins Superficially attached to lipid bilayer FUNCTIONS Channel proteins Allow movement of molecules that are too large/too hydrophilic to pass through membrane directly Carrier proteins Use E (= ATP) to actively move substances across the membrane
2.2 Movement
2.2.1 BY PASSIVE TRANSPORT Diffusion Free movement of particles (l or g state) down a concentration gradient Facilitated diffusion Diffusion that takes place through carrier proteins/protein channels Protein-line pores of cell membrane make it possible Osmosis Movement of solvent molecules down a concentration gradient, through partially permeable membrane E = kinetic
2.2.2 BY ACTIVE TRANSPORT Active transport Movement of substances across cell membranes, against a concentration gradient, using proteins in the bilayer which act as carrier proteins – these use energy in the form of ATP. ATP Common intermediate between energy-yielding reactions + every-requiring reactions/processes Formed from ADP through phosphorylation, which requires E (E used = energy released in respiration/ energy trapped in illuminated chloroplasts) Hydrolysis of ATP → provides accessible E for biological processes
2.2.3 BY BULK TRANSPORT Occurs through movement of vesicles of matter across cell membrane = cytosis Vesicles = membrane-bound organelles containing liquid or solid particles Uptake = endocytosis Export = exocytosis
2.3 Properties of transported material
2.3.1 Size Molecules too big to pass through carrier proteins/through membrane itself (eg. some proteins) → bulk transport
2.3.2 Solubility Particles with limited solubility → transported slowly When dissolved → dissociate into charged ions (= mobile + smaller)
2.3.3 Charge Structure of cell membrane makes it difficult for charged particles to pass through → electrostatic attractions/repulsions → prevents free movements Most ions + charged particles pass through membrane using specialised protein channels
3 4.3 – Gas exchange
3.1 Insects
3.1.1 Insects have no transport system so gases need to be transported directly to the respiring tissues.
3.1.2 Exoskeleton → made of chitin → impermeable to oxygen → barrier for gas exchange Spiracles in trachea (= valves connected to outside atmosphere) Gas exchange along trachea occurs in tracheoles → v thin walls → allows diffusion Oxygen High concentration of O2 in external atmosphere ≠ Low concentration O2 in tracheoles Carbon Dioxide Low concentration of CO2 in external atmosphere ≠ High concentration CO2 in tracheoles
3.2 Fish
3.2.1 Gills (specialised gas-exchange organs) → composed of thousands of filaments → covered in feathery lamellae (few cell thick + contain blood capillaries) Large surface area + short distance for gas exchange Blood flows through capillaries in opposite direction to flow of water over gills = counter-current flow system Maintains a concentration gradient along whole length of blood-water boundary
3.3 Mammals
4 4.4 –Circulation
4.1 Advantages of a double circulation
4.2 The Blood
4.3 Arteries, Veins and Capillaries
4.4 The Heart
4.4.1 CARDIAC CYCLE Periods of contraction = systole Periods of relaxation = diastole 1) Diastole ATRIA + VENTRICLES are RELAXING Blood flows from major veins (VENA CAVA + PULMONARY VEINS) into ATRIA, then into VENTRICLES, via ATRIOVENTRICULAR VALVES OPEN atrioventricular valves → PRESSURE in the ATRIA is GREATER than that in the VENTRICLES CLOSED semi-lunar valves → PRESSURE in VENTRICLES is LOWER than that in MAIN ARTERIES 2) Atrial Systole BEGINNING of the MUSCLE CONTRACTION ATRIA CONTRACT → pushes MORE BLOOD into the VENTRICLES 3) Ventricular Systole VENTRICLES CONTRACT → increase in VENTRICULAR PRESSURE → blood pushes against ATRIOVENTRICULAR VALVES → snap shut → PREVENTS blood from FLOWING BACK into ATRIA PRESSURE in VENTRICLES continues to INCREASE until it is GREATER than that in MAIN ARTERIES → SEMILUNAR VALVES are forced OPEN → blood RUSHES OUT of VENTRICLES out of heart into ARTERIES VENTRICLES finished contracting → MUSCLES relax + PULLED BACK by ELASTIC TISSUE → DECREASES the PRESSURE in VENTRICLES → causes SEMILUNAR VALVES to SHUT + ATRIOVENTRICULAR VALVES to OPEN → so DIASTOLE PHASE can proceed once more → CARDIAC CYCLE restarts
4.4.3 STRUCTURE Right hand side → pumps deoxygenated blood to the lungs in the pulmonary artery → to pick up O2 + release CO2 Left hand side → oxygenated blood returns here via the pulmonary vein Blood pumped to the body in the aorta → returning to the right hand side of the heart in the vena cava → to start the cycle again 4 chambers → 2 atria above 2 ventricles (eg. Left atrium + Left ventricle) Atria = receive blood as it enters heart Ventricles = pump blood out heart Valve between left atrium + left ventricle = tricuspid valve Valve between right atrium + right ventricle = bicuspid valve Valves = prevent backflow of blood Valves are held open or closed by tendons → attached at the other end to the papillary muscles in ventricle walls Muscle of the heart = cardiac muscle Made of tightly connecting cells → allows rapid ion transport from cell to cell → allows smooth, efficient waves of depolarisation → to produce contractions (and repolarisation to bring about relaxation), which pass through the heart ∴ tissue = myogenic (doesn't need electrical impulses from nerve to make it contract) Supplied with O2 + nutrients by coronary arteries
4.5 Exchange in tissues –Tissue Fluid & Lymph
5 4.5 – Transport of gases in blood
5.1 Haemoglobin
5.2 Partial pressures
5.3 Oxygen dissociation curves
6 4.6 – Transfer of materials between the circulatory system and cells
7 4.7 – Transport in plants
7.1 Xylem
7.2 Phloem
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