Nutrient Absorption

How many different systems do you see? Digestive-Breaks down and absorbs nutrients 2. Respiratory- absorbs oxygen 3. Circulatory – transports nutrients

glucose + oxygen carbon dioxide + water + energy C6H12O6 + 6O2 6 CO2 + 6H2O + 36 ATP glucose + oxygen carbon dioxide + water + energy 1. Where does the glucose come from? Food 2. Where does the oxygen come from? Breathing 3. What are the final products of cellular respiration? CO2, H2O, ATP 4. In which organelle does this take place in our cells? Mitochondria

Evolutionary Trends of the Digestive System Types of digestive systems: Filter feeder Digestive cavity: 1 opening (Gastrovascular cavity) Digestive tract: 2 openings Description of system Aquatic animals that strain tiny floating organisms from water Digestive chamber with food entering and waste exiting through one opening. 2 openings: mouth, anus. Picture of system   Examples Sponges Jellyfish, Sea Anemone, Corals, Portuguese Man-of-War, Planaria (flatworm) Snails, oysters, squid, octopus, starfish, sand dollar, crayfish, spiders, crabs, butterflies, humans

Function of The Digestive System The function of the digestive system is to help convert foods into simpler molecules that can be absorbed and used by the cells of the body; eliminates waste.

The Digestive System (aka. Alimentary Canal) Includes: Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine/Colon Rectum (Accessory organs: salivary glands, liver, gallbladder, pancreas)

The Mouth Teeth Cutting, tearing, and crushing food into small fragments. Begins the process of mechanical digestion or physical breakdown. Saliva Secreted by the salivary glands. Helps moisten the food and make it easier to chew. Contains amylase, a digestive enzyme that begins the breakdown of carbohydrates. Begins the process of chemical digestion, where chemicals breakdown the large pieces into smaller pieces.

The Esophagus Bolus – Chewed clump of food. From the throat, the bolus passes through the esophagus, or food tube, into the stomach. Food travels through the esophagus to the stomach by smooth muscle contractions (wave-like) called peristalsis. The epiglottis (small flap covering the trachea) separates the food from air when swallowing

The Stomach Food from the esophagus empties into a large muscular sac called the stomach. The stomach continues the mechanical and chemical digestion of food. Mechanical: Stomach muscles contract to churn and mix stomach fluids and food, gradually producing a mixture known as chyme. Chemical: Gastric glands release mucous to protect the stomach wall Gastric glands produce hydrochloric acid and pepsin, which begins the complex process of protein digestion. Amylase is denatured by the stomach acid so carbohydrate breakdown does not occur in the stomach.

The Small Intestine Most of the chemical digestion and beginning absorption of the food you eat occurs in the small intestines.

The Small Intestine Divided into three parts: Together average about Duodenum Jejunum Ileum Together average about 6 meters (19.7 ft) long.

Duodenum The first of three parts of the small intestine. It is where almost all of the digestive enzymes enter the intestine. The pancreas and the liver release digestive enzymes and fluids to help with digestion in the small intestine.

Absorption in the Small Intestine By the time chyme enters the jejenum and the ileum parts of the small intestine, much of the chemical digestion has been completed. Chyme is now a rich mixture of medium and small nutrient molecules.

Absorption in the Small Intestine The small intestine is specially adapted for absorption of nutrients. The folded surfaces of the small intestine are covered with fingerlike projections called villi. Villi increases the surface area for absorption of nutrients

Absorption of Nutrients in the Small Intestine Nutrients are absorbed through the wall of the small intestine directly into the capillaries (blood) by the process of diffusion. Diffusion – movement of substances from an area of high concentration to an area of low concentration

Absorption in the Small Intestine By the time food is ready to leave the small intestine, it is basically nutrient-free. The complex organic molecules have been digested and absorbed, leaving only water, cellulose, and other undigestible substances behind.

The Large Intestine When the chyme leaves the small intestine, it enters the large intestine, or colon. Primary Function: Remove water from the undigested material that is left. The concentrated waste material (feces) that remains after the water has been removed passes through the rectum and is eliminated from the body. http://www.youtube.com/watch?v=Z7xKYNz9AS0

Click on picture

Accessory Structures of Digestion Pancreas Liver Gallbladder Salivary Glands

Pancreas Located just behind the stomach. Gland that serves three important functions: Produces insulin that regulate blood sugar levels. Produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acids. Produces sodium bicarbonate, a base that neutralizes stomach acid so that these enzymes can be effective.

Liver Assisting the pancreas is the liver, a large organ located just above and to the right of the stomach. Produces bile; to help digest fats Bile acts like a detergent, dissolving and dispersing the droplets of fat found in fatty foods. Makes it possible for enzymes to reach the smaller fat molecules and break them down. Bile is stored in a small, pouch-like organ called the gallbladder.

Gallbladder A pouch like organ that stores the bile http://www.youtube.com/watch?v=iCyk-670bdw (dr. oz) A pouch like organ that stores the bile The bile is brought to the small intestine by the bile duct 20 million ppl get gallstones, small hard mineral deposits due to excess cholesterol buildup

Salivary Glands There are 3 salivary glands: Parotid gland – largest of the salivary glands that secretes saliva to assist with chewing and swallowing; located in the cheek area inferior to the ear Submandibular gland – secretes amylase to help breakdown starches in the mouth; located below and inferior to the parotid gland Sublingual gland – secretes mucous that helps coat the food being swallowed; located in front of the submandibular gland on the floor of the mouth

Levels of Organization Digestive System Levels of Organization epithelium, villi, smooth muscle Mouth, esophagus, stomach, small & large intestines, etc… digestive Epithelial cells, Liver cell, stomach cell, pancreatic cell, etc….

A. SALIVARY GLANDS B. MOUTH C. ESOPHAGUS D. STOMACH F. LARGE INTESTINE E. SMALL INTESTINE H. ANUS G. RECTUM

Digestive System Disorders Peptic Ulcer Hole in the stomach wall Most peptic ulcers are caused by bacteria and most can be cured by antibiotics. Diarrhea or Constipation If not enough water is absorbed by the large intestine, diarrhea occurs. If too much water is absorbed from the undigested materials, constipation occurs. http://www.youtube.com/watch?v=cdijh32NiLs (constipation)