AISD - 2009

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Function: to provide oxygen gas need for cellular respiration and remove carbon dioxide from the body
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Invertebrate Organs:
◦ gills and trachae
Main Vertebrate Organs:
◦ Nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, lungs, gills, diaphragm

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Whether they live in water or on land, all animals must respire.
◦ To respire means to take in oxygen and give off carbon dioxide.
Some animals rely of simple diffusion through their skin to respire.
While others…
Have developed large complex organ systems for respiration.

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Invertebrate respiratory organs have
◦ large surface areas
◦ Are in contact with air or water
◦ If require diffusion they must be moist.

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Aquatic animals have naturally moist respiratory surfaces, and some respire through diffusion through their skin.
◦ Example: jellyfish and anemones
Some larger aquatic animals like worms and annelids exchange oxygen and carbon dioxide through gills.
◦ Gills are organs that have lots of blood vessels that bring blood close to the surface for gas exchange.

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Terrestrial invertebrates have respiratory surfaces covered with water or mucus. (This reduces water loss)
There are many different respiratory specialized organs in terrestrial invertebrates.
◦ Spiders use parallel book lungs
◦ Insects use openings called spiracles where air enters the body and passes through a network of tracheal tubes for gas exchange
◦ Snails have a mantel cavity that is lined with moist tissue and an extensive surface area of blood vessels.
How does respiration in aquatic invertebrates differ from that in terrestrial invertebrates?

Figure 29–9 Invertebrate Respiratory
Systems
Gill
Siphons
Tracheal tubes
Mollusk
Movement of water Insect Spiracles
Airflow
Spider
Book lung

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Chordates have one of two basic structures for respiration:
◦ Gills – for aquatic chordates
 Example: tunicates, fish and amphibians
◦ Lungs - for terrestrial chordates
 Examples: adult amphibians, reptiles, birds, and mammals

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Water flows through the mouth then over the gills where oxygen is removed
Carbon dioxide and water are then pumped out through the operculum

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As you move from amphibians to mammals the surface area of the lungs increases
◦ Insures a greater amount of gas exchange (or a two way flow of air).
Birds, by contrast have lungs and air sacs which have only a one-way flow of air.
◦ This allows for them to have constant contact with fresh air.
◦ This adaptation enables them to fly at high altitudes where there is less oxygen.

Nostrils, mouth, and throat
Trachea
Lung
Air sac
Salamander Lizard Primate Pigeon

Figure 37-13 The Respiratory System

Section 37-3
System
Oxygen-rich air from environment
Nasal cavities
Pharynx Trachea Bronchi
Bronchi Bronchioles
Oxygen and carbon dioxide exchange at alveoli
Trachea Pharynx
BIG
QUESTION
…
WHY DO ANIMALS BREATHE?
Nasal cavities
Alveoli
Carbon dioxide-rich air to the environment
Bronchioles