THE HUMAN DIGESTIVE SYSTEM

THE HUMAN DIGESTIVE SYSTEM

The Human Digestive System We will divide the Human Digestive System into two main topics: 1. Nutrition and what our body needs 2. How the human body breaks down food and makes it available for use by ALL CELLS.

How do living things get energy? 1. They get their energy from food or photosynthesis 2. After food is broken down in the body, it can be used in respiration to produce energy 3. The slow burning of food in your body is called oxidation 4. Some energy is given off as heat. 5. The waste products are carbon dioxide and water.

Calories The amount of energy required to raise one gram of water by one degree Celsius. You don t have to copy this down but, 1000 (Scientific) Calories equals 1 Food Calorie.

Different foods give off different amounts of energy. Fat Protein Carbohydrates 9 calories of energy/gram 4 calories of energy/gram 4 calories of energy/gram Boys your age need about 2800 calories/day Girls your age need about 2400 calories/day

Nutrition Require Nutrients which are found in food Nutrients are needed for energy, There are 6 kinds of nutrients: Carbohydrates Fats Proteins Vitamins Minerals Water growth, and all other life processes

Carbohydrates Carbohydrates are your main source of energy There are three kinds of carbohydrates: Simple (Sugars) Complex (Starches) Fiber

Types of Carbohydrates Sugar (Simple) Sugar like candy Used quickly by your body Gives your body short, quick bursts of energy Starch (Complex) Starches like bread and pasta Gives your body energy over long periods of time. Fiber Helps move food through your digestive system (and prevent constipation)

Fats Fats are found in: Steak, Ice Cream, Peanuts, Bacon, Oil, Lard, etc These are energy storage nutrients. The stored energy in fats is used if energy from carbohydrates is used up. Fats are used for insulation: to keep you warm Fats are used to protect/cushion your organs. 2 Types: Saturated Fats Unsaturated Fats

Protein Proteins are the building blocks of living material. You get protein from: Milk, fish, cheese, peanuts, eggs, and meat. Proteins are used for: 1. Energy 2. Growth and Repair (building tissues and muscles) 3. Making Enzymes: substances that regulate/control chemical activity. 4. Hormones: the chemical messengers of the endocrine system

Protein continued The building blocks of proteins are Amino Acids. Proteins are formed when smaller amino acid molecules join together. There are about twenty (20) amino acids. Twelve (12) are made in the body. Eight (8) must be taken into the body

Minerals Minerals are inorganic nutrients that help regulate chemical reactions and are needed by the body to develop properly Each Mineral has a different job: Iron Calcium Zinc Iodine Forms red blood cells, which carry oxygen throughout the body Build strong teeth and bones Aids in protein formation Controls body growth and oxidation of food

What happens when you don t get enough Iodine?

A condition called Goiter!

Vitamins Nutrients that are needed in small amounts (micronutrients) for growth, regulation of body functions, and prevention of diseases You get most of the vitamins you need from food. Exception: Vitamins D and K are made in your body If you don t get enough vitamins you get a deficiency Vitamin B 2 Vitamin C Vitamin A Helps release energy from nutrients Growth and repair of body tissue. Lack of Vit. C leads to scurvy Enhances night vision, and maintains skin and bones.

Water All the chemical reactions in the body take place in water. Water carries nutrients to and from the organs It helps your body maintain its temperature You get water from the foods you eat and the fluids you drink. Your body is about 50%-60% water.

The Ever Evolving Food Pyramid

How do we break down food? Mechanical Digestion Breakdown food physically, using pressure to break apart larger chunks. Example: Chemical Digestion Breaking down food using water, enzymes, acids, etc Example: You body uses mechanical digestion to increase the surface area of food, which speeds up chemical digestion.

How do we move food? Using muscles we can control Chewing and Swallowing Using muscles out of our control Stomach Churning Peristalsis: A wavelike muscle contraction to squeeze food through a tube. http://www.westga.edu/~lkral/peristalsis/index.html http://www.innerbody.com/anim/mouth.html

The Digestive Pathway Mouth (Food) Mechanical Dig Teeth Chemical Dig Salivary Glands Saliva with Ptyalin Throat / Pharynx (Bolus) A tube to transport food water and air

The Digestive Pathway Mouth (Food) Throat / Pharynx (Bolus)

The Digestive Pathway Epiglottis (Bolus) Directs: Air to Lungs Water to Food to (Respiratory System) Stomach (Digestive System) Stomach (Digestive System)

The Digestive Pathway Epiglottis (Bolus) Source centerforsoundsleep Source mycotopia

The Digestive Pathway Esophogus (Bolus) Moves the bolus using Peristalsis Source centerforsoundsleep Source mycotopia

The Digestive Pathway The Stomach Mechanical Dig Churning (Bolus) Chemical Dig HCl to digest Carbs. (Hydrochloric Acid) Pepsin to digest Proteins (Enzyme)

The Digestive Pathway Small Intestines (Chyme) Moves food using Peristalsis Increases surface area with villi Digestion of Fats begin here First section: The duodenum Chemically breaks down food using secretions from the: Pancreas Liver

The Digestive Pathway Small Intestines & The Accessory Organs The Pancreas and Liver Pancreas Liver Secretes Pancreatic juices to breakdown nutrients Creates Bile: Breaks down Fats Stored in Gall Bladder

The Digestive Pathway Small Intestines Second Section (Chyme) Now that your food is FULLY BROKEN DOWN (digested) Nutrients are absorbed by the villi What increases the rate/amount of absorption? The villi s shape increase the surface area The intestines are looonng. The chyme is pushed through by peristalsis.

The Digestive Pathway Large Intestines Now that your food is FULLY ABSORBED Reabsorbes: Water Vitamin B & K (Feces)

The Digestive Pathway Rectum Anus Feces is stored here Feces is expelled here

Epiglottis Tongue Salivary Gland Esophagus Liver Gall Bladder Stomach Bile Duct Duodenum Pancreas Small Intestines Villi Appendix Anus Rectum Large Intestines

http://www.innerbody.com/anim/mouth.html