Exchange of carbon dioxide and oxygen for photosynthesis and cellular respiration
Respiratory Medium
Air
Terrestrial animals and plants.High oxygen concentration.
Respiratory surface loses water.
Water
Aquatic animals and plants.Keeps respiratory surface moist.
Oxygen concentration much lower than air.
Respiratory Surface: Thin membrane rich in blood supply.
Skin: moist epithelium with a capillary network under the surface.
Gills: evaginations of body surface exposed to water.
Tracheae: chitin-lined air tubes leading inward from the body surface.
Spiracles: entrance to tracheae.
Lungs: invaginations of body surface
alveoli: microscopic pockets of epithelium.
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 ? pharynx ? larynx ? trachea ? bronchi ? bronchioles ? alveoli
Passageway lined with mucous membrane.
Ciliated cells move mucus and trapped particles to the throat to be eliminated.
The Respiratory System
Breathing
Inspiration
Diaphragm contracts.Pressure in lungs and alveoli decreases. Lungs expand.
Air rushes into lungs.
Expiration
Elastic recoil of lungs increases pressure, forcing air out.Diaphragm returns to relaxed position.
Control of breathing: brainstem.
Factors that Affect Breathing
Presence of carbon dioxide in the blood.Degree to which lung tissue stretched.
Emotional state.
Transport of Gases
Oxygen
Hemoglobin (98%).Dissolved in plasma (2%).
Carbon dioxide
Bicarbonate ions (70%).Carbaminohemoglobin (23%).
Dissolved in plasma (7%).
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.