1. Savannah Halil & Katie Lahey
Respiratory System
is the sequence of events that results in gas exchange between the body’s cells and the environment
Savannah Halil & Katie Lahey

2. gas exchange gas exchange surfaces rely on 3 things moist environment
thin surface
large surface in relation to the body
different types of animals and structures have different forms of a “respiratory system”
hydras
earthworms
fish
insects
terrestrial vertebrates

3. Hydras some animals have a larger surface area compared to their size
therefore, it is more efficient to exchange gases directly with the environment
(4.B.2 cooperative interactions within organisms promote efficiency in the use of energy and matter)
the outer layer is in contact with the environment
while gases are exchanged in the inner layer (Gastrovascular cavity)

4. Insects tracheae- a system of air tubes
allows oxygen to access cells without entering blood
all internal organs lie in the hemocoel
contains hemolymph
mixture of blood and lymph
break into tubes called tracheoles
oxygen flows almost directly into mitochondria

5. other methods? evidence that tracheae may expand and contract
comparable to the human lung
larger insects have air sacs (thin-walled and flexible) near major muscles
contraction and relaxation empties and draws in oxygen
if an insect or larvae lives in water than a spiracle is not used
instead diffusion across a body wall supplies the tracheae with oxygen
Example: mayfly and stonefly
4.A.4: Organisms exhibit complex properties due to interactions between their constituent parts

6. Earthworms
segmented worms (annelids) also provide adequate surface area for external respiration
its capillaries come close enough to the surface that gases can be exchanged
2.A.3 Organisms must exchange matter with the environment to grow, reproduce, & maintain organization
It is important for the worm to keep the surface of its body moist
fluid is secreted from pores
adapted to stay in damp soil during the day

7. terrestrial vertebrates
2.D.2: Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments.
lungs are divided into small passageways and spaces
human lungs surface area is 50 times the skins surface area
air is richer in oxygen than water but can also dry out the lungs
lungs are deep in the thoracic cavity to protect them from drying out
also protected from mucus, dust and food by the cilia
warmed and humidified before reaches lungs

8. food and oxygen air and food pathways cross in the pharynx
passes from pharynx through glottis (opening into larynx, voice box)
also where voice box is located
larynx and trachea are always open
held open by nine cartilages
when food is swallowed the larynx rises, the glottis is closed by tissue called the epiglottis and enters the esophagus

9. trachea
divides into 2 primary bronchi, which resemble the trachea in structure
enter left and right lungs
continues into smaller passages called bronchioles
each bronchiole terminates into air pockets, or sacs, called alveoli
these structures make up the lungs and is where the internal gas exchange takes place

10. Fish
2.D.2: Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments.
Mouth and gills work in unison
mouth opens: opercula closes
mouth closes: opercula opens
so in detail…
the operculum protects several layers of gills
2. each gill has two rows of gill filaments
3. each filament is divided into capillary laden lamellae. (the blood flows in the opposite direction of the water)
4. gas is exchanged b/w the capillaries in the lamellae and the water that flows b/e the lamellae

11. How is it exchanged?
countercurrent exchange-two fluids flowing in opposite directions
in lamellae: oxygen rich water flows over the gills while blood within the capillaries flows opposite
with this kind of flow, water with a higher oxygen content is encountered
80%-90% of dissolved oxygen in water is extracted