More on digestion!

On saturday, we continued to talk about the digestive system. How do we measure the energy in food? Calories (Cal = kilocalories) - measurement of energy in food Calorie definition.
Where is energy stored= in matter!

Why do we need matter?
1. growth
2. tissue repair
3. copy DNA (we have to get some amino acids from other organisms)
Where does the matter go if you lose weight? 
CO2 (exhaled out), waste, water

The basic nutrient categories are listed below
Protein - 4 cal/g
Carbohydrates - 9 cal/g
Fats - 9 cal/g
Nutrients without calories but are necessary
Vitamins/Minerals 0 cal/g
H20 0 cal/g

The 4 stages of digestion
Ingestion - Taking food in involves oral cavity (Salivary Glands, Tongue, Teeth)
Digestion - Breakdown of food into small molecules
         a. Mechanical - Chew/Churn makes pieces smaller - increases surface area!
         (Why is increasing surface area so important??)
         b. Chemical - rearrange atoms so enzymes, chemicals have more surface area to work on!
Absorption - absorbs nutrients/water into blood (which moves them around the body)
Elimination - Release of undigested material (ex. non soluble fiber from plants, and other material (ex. dead cells)


Two 'sections' of the digestive system.
Alimentary Canal - tube made up of several organs where digestion happens. starts at the mouth --> pharynx --> esophagus --> stomach -->small intestine --> large intestine (colon) --> rectum --> anus. Food enters all these organs

Lined by epithelial tissues that secrete mucus which lubricates the channel and in the stomach helps prevent acids from destroying it.

Accessory (or Auxiliary) Organs -  organs that are part of the digestive system (food does NOT enter). These organs secrete enzymes and other digestive juices which are then put into the alimentary canal to aid digestion. (ex = salivary glands and amylase, pancreas, liver, gall bladder, appendix)