Animal Form and FunctionInternal Transport (Circulatory system)

Why do animals NEED an ITS?Cells need a constant supply of

nutrients and oxygenCells produce waste to be

removedSmall organisms can use

diffusion for these “tasks” but that is too inefficient for large organisms.

Functions of an ITSSupplies nutrients, oxygen,

hormones to cellsRemove CO2 and other waste

from cellsMaintain fluid balance,

temperature and defend against infection

What are the main structures of an ITS?Fluid – (ex: blood, haemolymph)

liquid that contains nutrients and wastes and some dissolved gases.

Pump – Heart that circulates the blood.

Vessels – network of vessels that transports blood.

Types of ITS’sOpen circulatory system – -Mainly found in invertebrates (insects, crustaceans, molluscs)-Blood is free to float through tissues of body cavity-Blood pumped by tubular heart-Blood enters through ostia and pumped toward head through dorsal vessel.-Diagram

Types of ITS’sClosed circulatory systems-Earthworms and vertebrates-Blood contained within vessels and pumped by a heart-Exchanges between blood and fluid around cells occurs by diffusion across capillaries.-Can be single or double circulation

Single circuit closed systemFish and earthwormsBlood is returned to heart after

every circulationDiagram:

Double Circuit closed systemMammals and other vertebratesDeoxygenated blood pumped to

lungs where it is oxygenated then returns to the heart where it is pumped again before returning to body to distribute oxygen/nutrients

Diagram

Diagrams you must know

Efficiency of the systemsClosed – single:-Blood loses pressure at gills and flows at low pressure around the body (overcome by swimming)-One circuitClosed – double:-High blood pressure maintained-Lungs circuit separated from body circuit

Pumps (Hearts)Earthworms – 5 “pseudo” hearts

with valves for one way flowInsects – tubular heart running

along dorsal surface, blood enters through ostia and pumped to head

Vertebrates – 2, 3, or 4 chambers. ATRIA collect blood and VENTRICLES pump blood

Vertebrate hearts con’t.Fish – 2 chambered (one A one V)Amphibians – 3 chambered (2 A

one V). Not fully divided, some mixing occurs (overcome by absorption from skin)

Mammals/Birds – 4 chambered (2 A 2 V). Oxygenated and deoxygenated separated.

Diagrams to know

Pigment (all about O2)Note: Haemolymph has NO

pigment because no O2!Haemoglobin – Found in closed

systems. Oxygen binds to IRON. Red when oxygenated, blueish when not.

Haemocyanin – Found in open systems. Oxygen binds to COPPER. Blue when oxygenated, clear when not.

Structure of bloodPlasma – 90% water, 10% proteins/ions

(for pH regulation and membrane permeability)/hormones/dissolved gases/nutrients/wastes

White blood cells and platelets – for defense and immunity (WBCs) and clotting (platelets)

Red blood cells – mainly to transport OXYGEN

Diagram

Components of blood

VesselsArteries - carry blood AWAY from the heart- Elastic and stretchy to withstand

high pressure- Muscle layer to help push blood

through - THICK outer layer- ARTERIOLES are small arteries

that deliver blood to capillaries

VesselsVeins- Return blood to heart (deoxygenated)- Same sort of structure as arteries, but

less elastic tissue- Many have one way valves to prevent

backflow- Blood is at low pressure (after passing

though capillaries- VENULES are small veins that return

blood from capillaries

VesselsCapillaries-VERY SMALL vessels that connect artery and vein systems-allow efficient exchange of gases, nutrients and wastes between tissues-present in the form of “beds”-Fluid leaks out and returned to blood system – some picked up by lymphatic (gland) system.