Bio Unit 2.3 - Gas Exchange in Animals Flashcards
What kind of SA to volume ratio do large organisms have?
Smaller
What kind of SA to ratio volume do smaller organisms have?
Larger
Why is unicellular amoeba good for effective gas exchange?
Large surface area to volume ratio so diffusion into cell is rapid
Why is thin membrane effective for gas exchange?
Diffusion distance inside cell is short, more rapid diffusion
Why does flatworm being enable effective gas exchange?
Flat - Larger surface area than a spherical organism of same volume
Think - short diffusion pathway, no part of the body is far from surface
Features of earthworm for effective gas exchange?
Cylindrical body, skin is respiratory surface, low O2 requirement, haemoglobin in blood
Features in multicellular organisms not seen in unicellular organisms
Higher metabolic rate, specialised cells, ventilation mechanism, thin respiratory surfaces
What do multicellular organisms need for efficient gas exchange?
Ventilation mechanism, circulatory system, respiratory pigment
3 main types of respiratory surfaces?
Gills, lungs, tracheal systems
All adapted to environmental conditions
Why do land animals have more difficulty with gas exchange than aqua animals?
Land is dry, respiratory surfaces are thin so lots of water can be lost through evaporation
What do gills have?
One way current of water flowing over them, many folds providing large surface area
What do cartilaginous fish (sharks) have instead of bone?
Skeleton of cartilage
Why are cartilaginous fish ventilation systems less efficient than bony fish?
Must keep swimming, parallel flow, oxygen diffuses from out to in, no more concentration gradient (50%), gas exchange does not occur continuously across whole gill lamella
Do bony fish or cartilaginous have a more efficient ventilation system?
Cartilaginous fish system is less efficient than bony fish
What covers the gills of bony fish?
Operculum
What happens when water is taken in to bony fish?
Mouth opens, operculum closes, floor of mouth lowered, volume inside mouth cavity increases, pressure inside mouth decreases, water flows in (external pressure higher than pressure inside mouth)
What do the gill lamellae hold?
Capillaries - gas exchange
What kind of current is in bony fish?
Counter current flow
Why is parallel flow less efficient?
Reduces concentration gradient, less oxygen absorbed, stops at 50%
During inspiration
Diaphragm flattens, diaphragm muscles contract, ribcage moves up and out, external intercostal muscles contract, volume of lungs increase, alveoli expand, alveolar pressure decreases
How is there large surface area in the lungs?
Millions of alveoli
How is there thin barrier to reduce diffusion distance in lungs?
Squamous epithelial tissue in alveolar walls
How is there steep diffusion gradient in lungs?
Oxygen diffuses from air where it is more concentrated to blood where it less concentrated. Difference is concentration gradient
What is surfactant and its function?
Made of moist secretions containing phospholipids and protein, low surface tension and prevents alveoli from collapsing during expiration
What is pleural membrane and its function?
Surround each lung and line thorax, keeps lungs from collapsing. Pleural fluid acts as a lubricant to prevent friction between lungs and inner wall of thorax
How do insects reduce water loss with a waterproof layer?
Exoskeleton made of thin wax layer covering layer of chitin and protein
Why can’t insects rely on simple diffusion through their body surface?
Small surface area to volume ratio
Where does gas exchange occur in insects?
Spiracles, holes open and close
What happens during flight of insects?
Abdomen muscles ventilate tracheae, oxygen dissolves into fluid and diffuses directly into muscle cells.
