Class Notes (806,874)
Canada (492,493)
Biology (2,220)
BIO271H1 (40)
Lecture 6

BIO271 2014 Lecture 6.pdf

12 Pages
Unlock Document

University of Toronto St. George
Christopher Garside

Lecture 6 Respiratory SystemsRespiration external respiration o sequence of events that result in the exchange of oxygen and carbon dioxide between the external environment and the mitochondria external respiration oxygen from the outside into the mitochondriacellular respiration cannot happen without external respirationneed to get oxygen in and carbon dioxide outMitochondrial Respiration o production of ATP by oxidation of carbohydrates amino acids or fatty acids o oxygen as a substrate o oxygen is consumed and carbon dioxide is producedconcentration gradient of oxygen and carbon dioxide these gases diffuse down their concentration gradientsgases do not react according to their concentration they react according to their partial pressures they dissolve and diffuse according to their partial pressures NOT their concentrationsconcentration of gases changes with changes in temperature and solubilitypartial pressures do not changeits the partial pressure of gases not the concentration thats importantgases react according to their partial pressuresunicellular and small multicellular organisms rely on diffusion for gas exchange o diffusion is faster over short distances but very slow over long distances o have to be thin with a large surface area to be able to completely rely on diffusionlarger organisms must rely on a combination of bulk flow and diffusion for gas exchangebulk flow o theres two types of bulk flow and two regions of diffusion o we have bulk flow ventilation diffusion at the pulmonary surface o we have bulk flow through the circulatory system then diffusion at the tissues 1 ventilationmoving medium externalair or water over respiratory surface lung or gillnot necessarily though other organisms can ventilate by moving around in the airpulmonary diffusion has to occur heregets into circulation then circulatory system will carry it around the body to the tissues that require oxygen at the same time picking up carbon dioxide waste products to get it out 2 circulationtransport of gases in the circulatory system peripheral gas exchangediffusion at the periphery tissuesDiffusion Through Water or Airunicellular organisms and small multicellular organisms living in aquatic environments can utilize diffusion gradient to drive gas exchange with the environmentoxygen simply diffuses into oxygen sinks mitochondriaconstantly utilizing oxygenalways a gradient for oxygen to come inanimals that obtain oxygen from air need an additional step gaseous oxygen much first dissolve before it can cross the cell membrane Bulk Flow of Waterdiffusion alone is too slow to maintain the rates of gas exchange needed to support the metabolism of large organisms because diffusion occurs slowly over long distancesstart ventilatingbulk flowno ventilation The oxygen can only diffuse so farlarger organisms rely on a combination of bulk flow and diffusion for gas exchangesponges and cnidarian move the external medium seawater by bulk flow through an internal body cavityoxygen diffuses from the seawater into the cells of the organism and carbon dioxide diffuses out of cells into the seawaterthe seawater circulating through the body cavity by bulk flow carries the carbon dioxide out into the environment Bulk Flow of Airinsects use similar system to bulk flow in watera series of hollow tubes called the trachea penetrates into all parts of the bodyair moves through these tubes either by diffusion of bulk flow and at the tissues oxygen from air dissolves in extracellular fluid and diffuses into the mitochondriawhile carbon dioxide diffuses out of the cells and into the trachea where it moves out to the external environment by diffusion or bulk flow this depends on speciesair into tissue Extra step always where gas needs to dissolve DiffusionGas Transportmany animals have a circulatory system that transports oxygen by bulk flow through the bodyin leeches and earthworms oxygen simply diffuses across the skin and is then carried by bulk flow through the circulatory system VentilationGas Transportanimals with internal gills or lungs move the external medium by bulk flow across the respiratory surface ventilationrespiration is divided into 4 steps 1 ventilation bulk flow of the medium across the respiratory surface 2 pulmonary diffusion diffusion across the surface 3 circulation bulk flow in the circulatory systemhas transport 4 peripheral gas exchange diffusion into the tissuesventilation and circulation is expensivelots of energy requiredneed to power musclesincrease in metabolic ratesrequire more oxygen to supply musclesfor bulk flow to occur you need to create a pressure gradient high pressure to low pressureno control for steps 2 and 4diffusion just happenscontrol only in circulation and ventilationair is a fluidhas to move through tubes to get into lungsPhysics of Fluid FlowLaw of Bulk Flow QPRQflowPpressure dropRresistance due to frictionFlow is directly proportional to the pressure dropgradient of where its flowing point A to Bincrease partial pressure gradient increase flowFlow is inversely proportional to the resistance increase resistancedecrease in flow 4 R8LrLlength of the tubeviscosity of the fluid o increase in viscosity of the fluidincrease in resistancerradius of the tube greatest effect o radius is most importantits to the power of 4changing the radius will significantly affect resistance o ex Half the radiusto get same amount of slowincrease pressure by 16 times power of 4 4 Poiseuilles equation QPr8 LMore detailed version of the bulk law
More Less

Related notes for BIO271H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.