C IRCULATORY SYSTEMS IN ANIMALS Biology ATAR Unit2 Chapter 11 Pages Heinemann Chapter 9, pages (handout)

Gastrovascular cavity Open circulatory system Tubular heart Ostia Open-ended vessels Interstitial fluid Closed circulatory system Heart Arteries Arterioles Capillaries Venules Veins Blood Multicellular organisms need a circulatory system to deliver nutrients and O2 and remove waste products and CO2 Organisms have different types of systems because of their size, their environment and their activity or metabolic rate KeywordsMaking connections

C IRCULATORY SYSTEMS Types of structures 1. Gastrovascular cavity 2. Open system 3. Closed system Function The circulatory system moves O 2 from the respiratory surface to the body tissues and removes CO 2 from the body tissue to the respiratory surface. It also transports nutrients, hormones and waste around the body where necessary.

G ASTROVASCULAR CAVITY : C NIDARIANS The gastrovascular cavity is responsible for both the digestion of food and the transport of nutrients throughout the body. The cavity has only one opening to the environment. Food goes in and waste comes out that same opening.

O PEN CIRCULATORY SYSTEM : I NSECTS An open circulatory system consists of a dorsal tubular heart (s) that, when it contracts, forces the fluid out of open- ended blood vessels This fluid flows through the spaces in the body and bathes the tissues and organs before returning through holes ( ostia ) to the heart. The fluid moves at low pressures and slow circulation speeds The fluid is not like blood, but like interstitial fluid Example: insects, snails

O PEN CIRCULATORY SYSTEM : I NSECTS These body fluids contain nutrients which are obtained from the digestive system They also contain metabolic wastes, which are disposed of by the excretory system. The insect has a separate respiratory system to exchange gases (O 2 and CO 2 ). In most insects, O 2 is delivered directly to the muscles through the tracheal system.

C LOSED CIRCULATORY SYSTEMS : L ARGE A QUATIC & T ERRESTRIAL ORGANISMS A closed circulatory system carries fluid within a network of arteries, capillaries and veins The fluid (blood) has the capacity to deliver nutrients and O 2 to cells and remove waste products and CO 2 from cells Blood does not leave the capillaries and does not come into direct contact with other body tissues Blood is oxygenated as it flows through the lungs Blood is moved through the system by a muscular heart The heart has 3 or 4 chambers separated by valves Example: reptiles, mammals, fish

C LOSED CIRCULATORY SYSTEMS

SUMMARY: O PEN & CLOSED CIRCULATORY SYSTEMS OPENCLOSED Transport fluidNo specialised transport fluid (interstitial fluid) Blood HeartSimple one or two chambered heart Three or four chambers with valves VesselsOpen-ended, of different lengths Arteries, arterioles, capillaries, venules, veins PressureVery low pressuresArteries – high pressure Veins – low pressure Time taken to circulate Long circuit timeShort circuit time ExamplesSnails, arthropodsBirds, fish, mammals