Gas Exchange

Gas Exchange

Exchange of carbon dioxide and oxygen for photosynthesis and cellular respiration

Respiratory Surface

Thin membrane rich in blood supply.
Skin: moist epithelium with a capillary network under the surface.
Gills: inward folds of body surface exposed to water.
Tracheae: chitin-lined air tubes leading inward from the body surface.

Spiracles: entrance to tracheae.

Lungs: outward folds of body surface

alveoli: small sacs; functional unit of the lungs.

Gas Exchange in Animals

Porifera: diffusion.
Cnidaria: diffusion.
Platyhelminthes: diffusion.
Nematoda: diffusion.
Annelida: diffusion through skin.
Gastropoda: gills or capillary network in mantle.
Bivalvia: gills.
Cephalopoda: gills.

Crustacea: gills aided by swimmerets.
Arachnida: book lungs.
Insecta: spiracles and tracheae.
Echinodermata: skin gills.
Chondrichthyes: gills.
Osteichthyes: gills covered by operculum.
Amphibia: skin, lungs, gills.

Reptilia: lungs.
Aves: lungs, air sacs.
Mammalia: lungs.
Passage of air: nasal cavity þ pharynx þ larynx þ trachea þ bronchi þ bronchioles þ alveoli
Passageway lined with mucous membrane.
Ciliated cells move mucus and trapped particles to the throat to be eliminated.

The Respiratory System

Gas Exchange In Plants

Root hairs absorb oxygen from the soil and release carbon dioxide by diffusion.
Lenticels in the stem exchange carbon dioxide and oxygen for cellular respiration.
Stomata in the leaves allow gases to enter the leaf. Gases diffuse across moist membranes of mesophyll of the leaf.

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