D IGESTIVE S YSTEM Outcomes to cover - 6 REMEMBER You do not have to copy the information printed in BLUE

M ATTER AND ENERGY EXCHANGE WITHIN DIGESTIVE SYSTEMS HELP TO MAINTAIN HOMEOSTASIS explain, using digestive systems, how different plant and animal systems, including the vascular and nervous systems, help maintain homeostasis (317-1) analyse natural and technological systems related to the digestive system, to interpret and explain their structure and dynamics (116-7) design an experiment, compile and organize data, and demonstrate a knowledge of WHMIS to investigate the effect of specified variables on the effectiveness of an enzyme (212-6, 213-5, 213-9) identify disorders linked to the digestive system and their effect on the homeostasis of the system and the organism as a whole (317-4)

G ENERAL S TEPS Ingestion = food is taken in (eating ) Digestion = Food is broken down into smaller pieces /molecules Absorption = Nutrient molecules are absorbed into body cells Egestion = elimination of undigested material exits the body

T WO T YPES OF D IGESTION Mechanical = Food is broken down into smaller pieces (chemical structure not changed) Chemical = Food is broken down into smaller molecules (chemical structure changed)

I NTRACELLULAR D IGESTION In the animal kingdom, only sponges (Phyla Porifera) do this exclusively. Steps: Cells engulf food via phagocytosis or pinocytosis, forming food vacuole. Lysosomes fuse with food vacuoles to digest food

E XTRACELLULAR D IGESTION All animals - except sponges Digestion begins in a gastric cavity (gut). Advantage of extracellular digestion? animal can take in a lot of food at once and slowly digest it

E XTRACELLULAR D IGESTION Enzymes - break food into smaller molecules. digestion may continue intra-cellularly. Animals that perform extracellular digestion can have a variety of different digestive systems.

G ASTROVASCULAR C AVITY Gastrovascular cavity = digestive sac with a single opening Examples Phyla Cnidarian hydra, jellyfish, anemones, corals

D IGESTION IN G ASTROVASCULAR C AVITIES Tentacles sting prey and stuff it into opening Digestive enzymes are secreted to allow for extracellular digestion food particles are engulfed and digested intracellularly Undigestible material leaves through mouth (no anus)

C OMPLETE D IGESTIVE T RACTS Complete digestive tract = digestive tube running throughout body (alimentary canal) Have both a mouth and an anus

Q UESTION … Why would having a separate entry and exit point be beneficial? digestion can be broken down into steps there can be specialization of digestive tissues for these steps

T ASK Using information provided label the human digestive system Using your text book, answer questions