• dissolved in plasma - ions, proteins, blood cells
• 45% of plasma volume is cellular elements, the remainder is plasma
• precapillary spihincter- adjusts blood flow into capillaries. smooth muscle fiber wraps around capillary
• gastrovaacular cabity - allcells are exposed to steps of digestion. ingestion og food in cavity, fragmented by enzymes. only one opening to environment, with food in and out there.
• factors that increase heart rate
• sterlings law, law of continuity
• diastole vs systole
• trace path of red blood cell from heart to systemic to heart
• four ways blood gets back to heart
• three gradients in capillaries
• blood pressure at capillary ends
• four components of blood
• hemocrit
• LYMPHATIC SYSTEM READING
• open circulatory - molluscs, arthropods, pumps blood into cavity called hemocoel, surrounds organs and returns to heart thru ostia (openings) . hemolymph is pumped thru blood vessel that empties into body cavity. low blood pressure, animals w low metabolisms. the hemolyph is shared with interstital fluid. and sloshes around hemocoel. the hemolymph can be pushed around withmuscle contraxtions no arteries or veins to pump hemolymph
• cardiac output- stroke volume x heart rate
• closed - all vertebrates, circulates blood to heart, organs then back . heart plumps thru vessels separate from interstitial fluid. pulmonary and systemic circulation. blood remains in vessels with high blood pressure
• advantage of open system - less energy needed for distribution. slow metabolism, small body

of closed system - faster level of distribution. moves, digests, wastes more rapidly,

• hemolymph - circulating fluid in bodies of some invertebrates
• inorganic salts in athe form of dissoved ions (blood electrolytes). dissolved in plasma, which is 90% water. some of these ions buffer blood, salt maintain osmotic balance.
• platelets - fragments o cells involved in clotting
• red blood cells/erythrocytes - O2 transport. the biconcave shape increases surface area, enhancing rate of O2 diffusion. lack nuclei, leaves more space for hemoglobin. lack mitochondria, ATP made via anaerobic metabolism. oxygen transpor would be less efficient if aerobic. each hemoglobin can bind up to 4 oxygens. as red blood cells pass thru capillary beds of respitory organs, O2 diffuses into red blood cells and bhinds to hemoglobin. in systemic capillaries, O2 dissociates from hemoglobin and diffuses into body cells.
• leukocytes- white blood cells. fight infections
• gas exchange - uptake of O2 from environment, discharge of CO2 to environment.
• partial pressure - pressure exerted by a gas in mixture of gasses, or gasses dissolved in liquid.
• partial pressure of O2 - 0.21 (b/c atmosphere is 21% O2) x 760 mm Hg (atmospheric pressure at sea level)
• when water exposed to air, eq is reached when partial pressure of water= PP of air. but the concentrations are different. after calculating pp, we can predict net result of diffusion o gas exchange (gas goes rom high pressure to low)
• respitory medium - air or water
• air is easier bc less dense/viscous, so easier to be used by small passageways (does not have to be so efficient)
• gas exchange w water- amount of O2 dissolved in water is less than in air. the warmer and saltier the water is the less dissolved O2. greater density = marina nimals need more energy for gas exchange
• respitory surfaces must always be moist. movement of O2 and CO2 across moist resp surfaces is dependent on diffusion.
• gas exchange increases when area is large, path for diffusion is short. so resp surfaces have to be large and thin
• gills - outfoldings of the body that are suspended in the water

and often have a total surface area larger than the rest of the body's exterior.

• ventilation - movement of resp medium over the resp surface. this maintains pp gradients of CO2 and O2 across the gill.
• arrangement of capillaries in fish gill allows or countercurrent exchange. this increases gill gas exchange efficiency.blood flows in direction opposite to that of water over the gills. partial pressure gradient favors the diffusion of O2 from water to blood exists along the entire length of the capillaries in gills. blood flowing thru the capillaries within the lamellae picks up O2 from the water.
• gills cannot be used on land bc the expansive surface of wet membrane exposed to air would dry out and lose a lot of water thru evaporation. resp system must be moist, so our resp system is inside.
• tracheal system in insects- air tubes that branch out thruout the body (trachae). finer branches extend close to surface, gas is exchanged by diffusion across moist epithelium that lines tips of tracheal branches. tracheal system brings air within short distance of every body cell, this transports O2 and CO2 without participation of open circ system. small insects use diffusion to bring in O2 and drive out CO2, but larger ones need to ventilate their tracheal system with rhythmic movements that compress and extend the air tubes. ex. flying insect consumes a lot more O2 than it does at rest. related to bioenergetic.
• lungs- vertebrates that lack gills have lungs. amphibians have lubgs but are small and they rely more on their skin for exchange.
• when food is swallowed, the larynx moved upward and tips to epiglottis over the glottis (opening of the trachea). this allows food to go down esophagus and into stomach. when not swallowing. glottis is open to enable breathing; from larynx to trachea. vocal cords are in the larynx. trachea go into 2 bronchi, one to each lung. within the lung, bronchi to bronchioles.
• gas exchange occurs in alveoli, air sacs clustered at tips of branchioles. large total surface area. O2 entering the alveoli dissolves in moist lining and diffuses across epithelium into a web of capillaries surrounding the alveoli. CO2 diffuses from the capillaries across epitherlium of alveolus, then into air space
• how mammal breathes
• negative pressure breathi ng- pulling air into lungs. using contractions to expand thoracic activy. lower air pressure in lungs below that of the air outside body. thus the outside has higher pressure, and gasses go from high pressure to low, so air outside goes into lungs. in exhalation, the muscles contracting cavity relax, and volume of cavity is reduced. increases air pressure in alveoli forces air up breathing tubes and out of body, inhalation is always active, exhalation is passive'
• diapraghm - sheet of skeletal muscle
• inhalation - rib cage expands, rib muscle and diapgrahm contract
• exhalation - rib cage getsbsmaller and rib muscl and disgraphm relax
• blood flowing thru alveolar capillaries has lower PO2 and higher PCO2 than the air in alveoli. so CO2 diffsues down partial pressure graient from blood to air in evleoli. O2 dissolves from the air into the fluid that coats the alveolar epithelium and diffuses into blood.