Circulation Hannah Nevins Bio 1b Spring 2009 Transportation to and from cells Nutrients eg fatty acids glucose Metabolites wastes Hormones signaling cells organs Gases O2 ID: 460862
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Systems of transport within bodies
Circulation
Hannah NevinsBio 1b Spring 2009Slide2
Transportation to and from cells
Nutrients – e.g. fatty acids, glucoseMetabolites – wastesHormones – signaling cells, organsGases – O2,
CO2How are gases carried?Slide3
Circulatory System Components:
Circulatory fluid – carry solutes, gases, immune cells, RBCsVessels – “roads” for transport
Pump – to move fluidValves – to keep flow unidirectional (why?)Slide4
Cell Types: Red & WhiteSlide5
Components of (vertebrate) bloodSlide6
Simple Circulation: Ciliated Systems
Bodies <1 mm don’t need a complex system
Why not?Gastrovascular system is used for circulationCnidarians - Platyhelminthes
–
Ciliated digestive cavity with branching extensionsSlide7
Open Circulatory System:
E.g. Arthropods, MolluscsHemolymph is fluid
Fluid exits dorsal vessel – returns via ostia (veins)Drawbacks:
Backwaters & eddies
Not efficient
Poor oxygenation
Poor diffusion gradients
How can it be improved?Slide8
Open Circulatory System:
Hemolymph is fluidFluid exits dorsal vessel – returns via ostia
(veins)Drawbacks:Backwaters & eddies
Not efficient
Poor oxygenation
Poor diffusion gradients
How
could this system
be improved?Slide9
Open ClosedSlide10
Closed Circulatory System:
More efficient circulation = higher activity levelsSome invertebrates
Annelids - have multiple heartsCephalopods – 3 hearts: one to each gill and 1 for bodySlide11
Hemodynamics:
Capillaries greatly increase area –
Is this important? Why?Velocity changes with distance from heartHigh resistance in capillaries
Pressure varies with cardiac output
**watch movieSlide12Slide13
Venous flow – helped by muscle actionSlide14
Fish
Two-chambered heartDrawbacks:
Systemic blood is not pressurizedAs heart works harder, it gets blood that has reduced O2Slide15
Amphibians & some Reptiles
Two atria & 1 ventricleBlood mixed in ventricle
Greater systemic pressure = > higher activity levelsHeart gets fresher blood-Which of these has a greater density of skin capillaries? Why?Slide16
Variations in the circulatory system:Slide17
Four-chamber heart: Crocodiles, Birds and Mammals
No mixing of oxygenated and deoxygenated bloodWhat is the advantage of this?Slide18Slide19Slide20
Human Circulation:Slide21
Capillaries are everywhere!
2000/ mm2, usually <2% openSurface area = 1000 sq. miles!!(SC Co = 446 sq. mi.)Slide22Slide23Slide24Slide25
Capillary action
One-celled thick -leakyAllows for diffusion of nutrients & gases
Hydrostatic pressure forces blood out…Slide26Slide27
Capillary action
One-celled thick -leakyAllows for diffusion of nutrients & gases
Hydrostatic pressure forces blood outOsmotic pressure recaptures itLymph system captures the rest…