Bio2 Lecture 14

Bio2 Lecture 14 - Bio2 Lecture 14 Digestion(ch 45 Digestion...

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Bio2 Lecture 14 3/8/05 Digestion (ch. 45) - Digestion – heterotrophs take in and break down complex organic molecules into smaller molecules that can be taken into cells - This is how heterotrophs get their energy - Food food broken down for cellular respiration get ATP hydrolysis of ADP + P Gives off heat Work gets done work so we can run the systems of the body, make compounds, grow and repair tissues - Phagocytosis – done by organisms like amoeba, they engulf their food, called intracellular - Spongocoel – Sponges absorb food when the water passes through it, also intracellular - Gastrovascular Cavity – incomplete digestive system, hydra does this as do medusa, only has one opening, serves as mouth and anus - Gastrovascular Cavity – incomplete digestive system, done by flat worms, gets nutrients through absorption - One way tube – complete digestive system, by round worms and nematodes, one of the simplest systems, done by coelomates - One way tube – complete system, done by humans Food Processing - Ingestion – Getting food inside of us - Digestion – taking a hamburger and breaking it down mechanically as well as chemically, first in our mouths, then in our stomachs - Absorption – The food particles are broken down at the level where they can be absorbed - Elimination – Different from excretion, which is metabolic waste, this is solid waste - Food passes in sequence through the GI tract (Gastrol intestinal tract) - Mouth Pharynx esophagus (throat) esophagus stomach (where digestion occurs) small intestine large intestine rectum anus - Accessory organs: assist in digestion o Salivary gland – helps to break down carbohydrates o Liver – produces bile o Pancreas – produces enzymes o Gall bladder – stores bile Walls of the digestive system - First layer is mucosa , the inside layer, and the opening is the lumen, this is where food particles will be, what surrounds the food particles - There are villa on the mucosa which helps in absorption - Then is submucosa which has blood vessels, lymph vessels, and nerves, once food is digested it gets absorbed through submucosa
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