Presentation on theme: "Nutrition and Digestion Why do all living things need food? How do they get food? How do they break it down so it can enter their cell(s)? How does the."— Presentation transcript:
Nutrition and Digestion Why do all living things need food? How do they get food? How do they break it down so it can enter their cell(s)? How does the food get to every cell in multicellular organisms?
Producers vs consumers Autotrophs: Make own food Chemosynthesis (Archaea) Photosynthesis (Protists, plants) Heterotrophs: Cannot make own food Intracellular (within cell, Amoeba, Paramecium) Extracellular (outside cell, molds, Hydra)
How is surface area increased? How is the increased surface area of the intestine an adaptation?
Earthworm Mouth – ingests & moistens food Pharynx – muscular contractions pull food from mouth Esophagus – muscular contractions push food to crop Crop – storage organ Gizzard – gravel & muscular contractions grind food to small particles Intestine – enzymes digest food into small molecules which are absorbed through intestinal walls. Anus – expels undigested material or “castings"
Physical vs. Chemical Digestion Physical Food is broken down into smaller pieces – increasing surface area for chemical digestion Chemical Enzymes cause large molecules break down into smaller molecules that can pass through the plasma membrane
Food intake patterns Chunk feeders Take in food in large pieces Require structures for physical/mechanical digestion, e.g., teeth, gizzard Require enzymes to provide chemical digestion, e.g., amylase, pepsin, lactase
Food intake patterns Filter feeders Feed on microorganisms and/or nutrients floating in water Sessile or slow-moving Take water into body; filter out food; expel water Include bivalves (clams, oysters) and baleen whales
Sponges Cells with flagella draw water through pores =food particles are filtered out
Mouth– physical and chemical digestion Teeth grind food into smaller pieces to increase surface area 3 pairs of Salivary glands secrete saliva Moistens food Starch amylase maltose (polysaccharide) (disaccharide)
Pharynx & Esophagus Peristalsis – contractions of smooth muscle move food to stomach
Stomach Physical digestion: Churning Chemical digestion: Pepsin + hydrochloric acid break protein down into polypeptides. Storage: Releases chyme slowly into small intestine pH = 2 Mucous layer protects stomach from digestion! rugae
Small intestine Digestion is completed – Fats are emulsified by bile and then digested by lipase. Nutrients are absorbed through walls of villi into bloodstream
Pancreas secretes pancreatic fluid containing enzymes: Trypsin – proteins to peptides Amylase – starch to maltose Lipase – fats to fatty acids + glycerol Liver produces bile which is stored in the gall bladder (emulsifies fats) Accessory Glands
Large intestine Water and salts are reabsorbed. What can be dangerous about having diarrhea? Feces stored in rectum – eliminated through anus. anus