How Do You Build the Molecules of Life? Better Known as Organic Molecules and Digestion…

Living Creatures Have Organization All organisms are made of the same collection of chemicals, which are organized into… Molecules Made up of proteins, fats, carbohydrates, and nucleic acids

Molecules are then organized into… Organelles & Cells, specifically… Plant Cells & Animal Cells Living Creatures Have Organization

Going from a cell to baby…. The original fertilized egg has to divide into groups of cells The groups of cells work together to perform the same function and form tissue Living Creatures Have Organization

Tissue is then organized into… Organs & Organ systems Respiratory, Circulatory, Digestive, etc. Living Creatures Have Organization

Making the Body Systems Work Animals make energy using food and oxygen Animals build bodies using: Food for raw materials Amino acids, sugars, fats, nucleotides ATP energy for synthesis But where do we get the raw material from? Food we eat! O2O2 Food ATP

Getting & Using Food Ingest: Taking in food Digest Mechanical digestion Breaking up food into smaller pieces Chemical digestion Breaking down food into molecules small enough to be absorbed into cells Enzymes are proteins that help to speed up the breaking down process Absorb: Absorb across cell membrane Diffusion Active transport Eliminate: Undigested material passes out of digestive system intracellular digestion extracellular digestion

Digestive Systems – Many Forms

Ingestion Starts Digestion Mouth Mechanical Digestion Chemical Digestion Saliva -Enzyme digests starch Slippery protein Protects soft lining of digestive system Lubricates food for easier swallowing

Oral Cavity Upper lip Lower lip Uvula Tongue Palate

Salivary Glands Scattered throughout oral cavity Functions: Hydrolysis Dissolve things Moisten food and mouth Composition of saliva pH (Slightly acidic) Produce ml a day 99% of saliva is water Salivary amylase begins breakdown of starch

Esophagus Moves both air and food Epiglottis, a flap of tissue, prevents food from entering the trachea Food enters the esophagus instead Muscular contractions and relaxations called peristalsis moves food through the esophagus

Stomach Can stretch to hold 2 L of food “Growling” is contracting of stomach muscle Three layers of muscle churn the food Gastric pits in the stomach secrete acidic digestive fluid Mucus protects the stomach lining – ulcers are a breakdown of this protective lining Mixed food particles and gastic fluid is called chyme Fundus Duodenum Esophagus Body Pylorus

Stomach Disinfect food HCl = pH 2, will kill bacteria Chemical Digestion Digestion of proteins by pepsin, a gastric protease, into peptides. Gastric lipase- pH 5-6, splits lipids

Liver Produces bile to break up fats Bile is composed of bile acids and salts, phospholipids, cholesterol, pigments, water, and electrolyte chemicals Bile stored in gallbladder until needed Large organ right of the stomach Stores glucose, makes proteins, breaks down toxins – including alcohol

Pancreas Lies behind the stomach Produces sodium bicarbonate, to neutralize stomach acid to protect the small intestine Produces insulin in the Islets of Langerhans, specialized cells in the pancreas Pancreatic juices: Pancreatic amylase – breaks down all starches Trypsin, Chymotrypsin – separates amino acids (proteins) Pancreatic lipase - breaks down lipids Nucleases - break down nucleic acids Islet of Langerhans

Gallbladder A pear shaped sac on underside of the right lobe of the liver. About 7-10cm long. Ducts Hepatic ducts Cystic ducts Common bile ducts Function Store and concentrate bile by absorbing water Contracts and releases bile to duodenum when needed

Small Intestine Nearly 7 m in length Three sections: Duodenum (25 cm), Jejunum (2.5 m) and Ileum (4 m) Intestinal Juices Maltase, sucrase, lactase – break down carbohydrates Aminopeptidase, Dipeptidase – break down amino acids (proteins) Deoxyribonuclease, ribonuclease- break apart sugars and nucleic acids

Duodenum First section of small intestines Receives acid food from stomach Mixes with digestive juices from: Pancreas Live Gallbladder

Absorption by Small Intestines Highly folded lining of the small intestine is called villi, which are covered in microvilli Give a surface area about 250 square meters (area of a tennis court) 90% of all nutrients are absorbed in the small intestine, 10% in stomach and large intestine. Carbohydrates: absorbed on surface of villi. Proteins: amino acids are transported by active transport into the capillaries Water absorption: absorption accomplished by osmosis Lipids: lipase breaks down glycerol Circular creases with villi

Colon Also known as large intestine Four parts – ascending colon, transverse colon, descending colon and sigmoid colon Waste solidifies into feces and >90 % water is reabsorbed Diarrhea: not enough water absorbed Constipation: too much water absorbed Rectum Sigmoid Descending colon Transverse colon Ascending colon Anus

You’ve Got Company! Living in the large intestine is a community of helpful bacteria Escherichia coli (E. coli) produce vitamins vitamin K; B vitamins generate gases by-product of bacterial metabolism methane, hydrogen sulfide

stomach  kills germs  break up food  digest proteins  store food mouth  break up food  digest starch  kill germs  moisten food small intestines  breakdown food - proteins - starch - fats  absorb nutrients pancreas  produces enzymes to digest proteins & carbs liver  produces bile - stored in gall bladder  break up fats large intestines absorb water

Appendix Vestigial organ located behind the ascending portion of colon Darwin suggested it might been used to digest cellulose Scientists are now studying how it might influence the immune system

Rectum Last section of colon Eliminate feces which are undigested materials extracellular waste mainly cellulose from plants masses of bacteria

Length of Digestive System Herbivores & Omnivores Long digestive systems Harder to digest cellulose Carnivores Short digestive systems Protein easier to digest

Teeth Carnivore sharp ripping teeth “canines” Herbivore wide grinding teeth molars Omnivore both kinds of teeth

Vegetarian Diets Need to make sure you get enough protein 20 amino acids to make protein 10 amino acids humans can produce 8 “essential amino acids” come from food Grains (like corn) have 6 (missing 2) Beans (like soybean & red beans) have 6 (missing different 2) Mix beans & grains for complete group of amino acids Rice & Beans Tofu & Rice Peanut Butter & Bread

Feedback: Maintaining Homeostasis Balancing glucose levels in blood pancreas insulin liver takes up glucose for storage cells take up glucose from blood liver releases glucose to blood depress appetite stimulate hunger glucagon