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

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

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)

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

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

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

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

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

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

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

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