Module 3-Section 1 - Exchange and Transport - Flashcards in A Level and IB Biology

Single-Cellular Organisms

High Surface Area:Volume Ratio Short Diffusion Distance Doesn't need a exchange system as oxygen and carbon dioxide can diffuse through thin membrane.

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Multi-Cellular Organisms

Low Surface area: Volume ratio Large distance between cells and oxygen outside the body Use oxygen faster, so release more carbon dioxide Need a specialized exchange exchange system to efficiently get oxygen around the body

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Features of a Specialized Exchange System

Thin surface area-Shorter diffusion distance. Ventilated - To increase efficiency. Good blood Supply - Replace oxygen - Maintain a concentration gradient. Large Surface Area - Lots of space to diffuse oxygen in and carbon dioxide out.

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Trachea Structure

C-Shaped Cartiledge-Provides support. Elastic Fibres-Fibres recoil pushing air out when exhaling Ciliated Epithelium (contains Goblet Cells)- Secrete mucus to stop micro-organisms reaching alveoli. Smooth muscle-Allows diamet

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Broncus Structure

Cartiledge-Provides support. Elastic Fibres -Fibres recoil pushing air out when exhaling. Smooth muscle-Allows diameter to be controlled. Ciliated Epithelium (contains Goblet Cells)- Secrete mucus to stop micro-organisms reac

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Bronchiole Structure

Ciliated Epithelium (contains Goblet Cells)- Secrete mucus to stop micro-organisms reaching alveoli. Smooth muscle-Allows diameter to be controlled. Elastic Fibres - Fibres recoil pushing air out when exhaling.

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Alveolus structure

Elastic Fibres -Fibres recoil pushing air out when exhaling. Alveolar Epithelium

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Insiration

1.Intercoastal muscles contract-causes rib cage to move up and out. 2.Diaphragm contracts-causes it to move down and flatten 3.Thorax volume increases 4.Air Pressure decreases 5.Air flows in

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Expiration

1.Intercoastal muscles relax-causes rib cage to move in and down 2.Diaphragm relaxes-Becomes curved again 3.Thorax volume decreases 4.Air pressure increases 5.Air flows out

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Spirometer

1. Breathe in 2. moves oxygen chamber as breathe it in 3.Creates spirometer trace 4.Carbon dioxide absorbed by soda lime

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Ventilation in Fish

1.Buccal Cavity floor falls 2.Volume increases 3.Air pressure decreases 4.Buccal cavity floor raises 5.Opperculum opens-allows water to flow through gill filaments then leave 6.Volume decreases 7.Air Pressure increases

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Gas Exchange in Fish - Gills

1.Water passes through gills 2.Gill filaments and gill plates increase surface area 3.Gill plates has lots of capillaries and thin layer of cells to speed up diffusion between water and blood

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Counter-Current system

Water flows one way and Blood the other to maintain the concentration gradient, so maximum oxygen diffuses into the blood

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Gas Exchange in Insects

1.Air moves in through spiracles to tracheae 2.Oxygen travels down conc gradient into cells 3.Carbon dioxide moves toward spiracles to be released 4.Tracheoles contain fluid in which oxygen and Carbon dioxide diffuse in this and into cells

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Ventilation in Insects

Rhythmic abdominal movements change volume in body and moves air in and out of spiracles (In larger flying insects use wing movements to pump thorax too)

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Module 3-Section 1 - Exchange and Transport

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