Gas Exchange and Transport

Moist membranes that cover lots of surface area

movement of oxygen or carbon dioxide into/out of cell

Simple gas exchange from fluid in a branching or simple gastrovascular cavites into cells

• gas exchange through skin common is small thin organisms
• Worms have larger surface area with bumps,

• respiratory tubes called trachea open into spiracles
• subdivide into many branches to get close to many cells
• no oxygen carrier or special cells needed, no blood stream intermediate, more fast efficient 
• Direct diffusion of gas limits size

• Usually breathe through skin even though they have small lungs
• Need to be moist

• SA internally is larger than skin via branching or folding
• Do internally because external would dry out on land (ex: birds reptiles)

Use lungs and some use cloaca as secondary and exchange unit

• are homeotherms, maintain constant body temperature
• Use muscle heat to maintain
• Use lungs similar reptiles but also have air sacs which allow fresh to flow through lungs during exhalation

• Use lungs similar reptiles but also have air sacs which allow fresh to flow through lungs during exhalation
• Holds more air than lungs can take in so on exhale old air and inhale has excess air, new air to use air flows only one direction (unlike mammals)

• Breathe in water through branching gastrovascular cavities
• Simple tubular projections from the body with added SA
• Dont have to worry about keeping moist
• Must be more efficient at removing oxygen from water because only holds a fraction of oxygen that air does
• Blood vessel so thin only blood can pass through one cell at a time
• Four gill arches are found on either side of the head in thin filaments just out from each bony arch
• Each filament has 100's of lamellae where diffusion of oxygen into blood happens
• *Key aspect blood is flowing toward head of fish and water flowing toward tail as swims
• Countercurrent exchange

• favors high diffusion
• high oxygen moves along blood across the gill gradient (moves in opposite direction) in order to encounter the highest gradient difference in concentrations
• 

• Circulatory system is needed to bridge gap between lungs and cells
• End in blind sacs called alevoli

Dense net of capillaries which oxygen diffuses and co2 is excreted

• nose to mouth, air entrees pharynx across larynx (lies within tachea)
• trachea goes into two bronchi and further into bronchioles

Thoart

Voicebox

Windpipe

• Deoxygenated blood enters lunch capillary
• Low partial pressure of oxygen
• Inhaled air has high partial pressure
• Therefore oxygen moves into capilariess
• CO2 opposite so it moves out of body

hormone released by kidneys increases red blood cells

Red Blood Cell

Made of four subunits capable of biding to four oxygen molecules

Loading becomes easier after the first oxygen

• Hemigobin losses oxygen more easily in acidic environments
• Carbonic acid from krebs cycles makes more acidic

• An open circulatory system 
• No distrinction between blodd and intestitual fluid (hemolymph)
• Ventilation system in insects is completely distinct
• Tracheal tubes bring oxygen throughout hemolymph to pick up oxygen

• First Closed circulatory system
• Diffusion of gases and nutrients occur into and out of blood
• Blood and interstitial fluid dont mix
• oxygen and nutrients diffuse out of blood into interstitial fluid from fluid to cells

• One atrium where blood is recieved
• One ventrical pumps blood back out of gills
• No oxygened blood flows into heart because only oxygenated by gills 
• Swimming movements help push blood through body
• One circuit out to gills through body and back to heart

• In reptile and amphiians
• Two separate atria and one larger ventricle
• Two circuit-out to lungs 1st then body stop at heart between ciruit, may be an evolutionary development from lungs
• More efficient because blood can be delivery with high velocity for each circuit (stops at heart in between)

• Division that almost cuts ventricle in half
• Progression to four chambers allows for separation of oxygenated and deoxygenated blood

• Mammals and birds
• Double Circuit
• Each side has own pump
• Right pump deoxygenated blood to lungs
• Left side pumps oxygenated to aorta and out of body

• Two upper receiving chambers are artia
• Two lower are ventricles, muscular

• Between artia and Ventricle prevent back flow of blood into atria
• Semilunar valuves in pulmonary artery prevent back flow of blood into lungs

Period between ventricles contracting and forcing blood into luncgs and aorta

ventricles contract and fill with blood

• Force/ area blood exerts on walls of blood vessels
• Systole/Diastole #

Often collapse on themselves when not filled with blood

Contain an open lumen and can contract against themselves to propel blood away from heart

Maiin artery leading away from left ventricle

Small bands of muscles that close off capilaries when not in use (not enough blood in the body to keep them always open)

• Spincters close when cold to restrict heart losse
• More blood near surface means more heat lost

• Keeping lots of blood vessels in extremities open
• Helps sweat and cooling body