What is roughage and if we can't digest it why is it good for us? Also, why can't we digest it?

Background:

Nutrition is the process of taking in molecules (food) from the environment and changing into usable forms. It is one of the life functions that were discussed in chapter 1. Nutrients are substance that can be used in metabolism. There are 6 types of nutrients; carbohydrates, fats, proteins, water, vitamins & minerals. Plants absorb minerals from the ground and animals obtain minerals by eating plants. This fact leads us to two different types of nutrition.

I. Types of Nutrition

A. Autotrophic nutrition: make their own food

1. photosynthesis- get energy from sun
2. chemosynthesis- get energy from organic chemicals

a. example-- bacteria, plants on the bottom of ocean

B. Heterotrophic nutrition: can't make their own food

1. Steps for heterotrophic nutrition

a. Ingestion- bringing food into the organism
b. Digestion- process by which food molecules are broken down & absorbed

1. mechanical digestion- chewing, increases surface area for enzyme action
2. chemical digestion- hydrolysis; carried out by digestive enzymes

c. Egestion- getting rid of indigestible matter; feces or stool

2. The rest of the notes focuses more on heterotrophic nutrition

II. Adaptation for Protazoan Nutrition which belong to the Protist Kingdom

A. Protazoa- unicellular animal-like organisms lacking specialized organs for nutrition

1. digestion occurs within the cell in a food vacuole
2. below you can see a paramecium within the food vacuole of an ameba

III. Adaptation for Organisms of Fungi Kingdom

A. Mushrooms for example use extracellular digestion by secreting enzymes outside its cells where digestion occurs so that absorption can take place into the cell

IV. Adaptation for Animal Nutrition

A. HYDRA- animal which belongs to Phylum Ceolenterata "hollow body cavity"

1. ingestion uses tentacles to capture & sting food, stuff into mouth
2. digestion: begins outside cells in the gastrovascular cavity (extracellular digestion) & then nutrients are absorbed + digestion is completed inside cell (intracellular digestion)

a. phagocytic cells line the digestive cavity & digest food intracellulary

3. one opening serves as both a mouth & anus

 

B. EARTHWORM- animal which belongs to Phylum Annelida "segmented worms"

1. is termed "tube-within-a-tube" body
2. inner tube is the digestive tract or alimentary canal
3. alimentary canal consists of (in order)

a. mouth-pharynx-esophagus-crop-gizzard-intestine-anus

C. GRASSHOPPER- animal which belongs to Phylum Arthropoda "jointed-legged"

1. more advanced digestive system because it contains salivary & other digestive glands that aid in digestion

a. gastric caeca- produces enzymes to help break down food

D. HUMAN DIGESTION SYSTEM (notes are arranged in terms of flow of food through the alimentary canal

1. MOUTH (oral cavity)-

a. mechanical digestion- name teeth
b. chemical digestion- salivary glands (accessory organ) adds saliva, enzyme amylase (start of carbohydrate digestion)

starch (amylose) which is a polysaccharide-----> maltose (disaccharide)

c. Bolus: mass of food that has stuck together in mouth

2. PHARYNX- (back of throat) swallowing reflex

3. ESOPHAGUS (gullet)- tube from mouth to stomach which bolus travels

a. Epiglottis- blocks passage to trachea during swallowing
b. Larynx- voice box at top of trachea which receives air, not food
c. Peristalsis- muscular contractions move food along to cardiac sphincter
d. Cardiac Sphincter- "valve" between stomach and esophagus
e. Vomiting- reverse peristalsis, cardiac sphincter opens and food moves up.

4. STOMACH- thick walled, muscular sac, mechanical & chemical digestion occur here

a. pyloric glands in stomach- secrete mucus which covers the stomach lining & protects it from being digested
b. gastric glands- secrete gastric juice which contain hydrochloric acid (HCI), water (H2O), pepsin or protease (enzymes that digests proteins starts)

1. the thought, sight, smell, taste + touch of food stimulates the flow of gastric juice

c. Chyme- solid food which is turned into a thin soupy acid liquid within stomach
d. Ulcer- the stomach is digesting itself caused by a bacteria
e. Pyloric sphincter- muscle that connects the stomach and small intestine

5. SMALL INTESTINE- 30 feet long, site where most digestion occurs

a. Peristalsis- moves chyme along & mixes it with digestive enzymes
b. intestinal juice is mixture of enzymes produced by intestinal gland
c. Pancreas- accessory gland produces pancreatic juice which is mixture of enzymes added to small intestine
d. Liver- accessory gland produces bile which is a fluid which aids in the breakdown of fats (emulsification); is stored in the gallbladder then released into small intestine
e. contents of small intestine have basic pH because of bile
f. Villi- small finger like projections in the lining of the small intestine which absorb end products of digestion, increase surface area for absorption
g. Appendix: joins small intestine with large intestine; small pouch that plays no part in digestion

6. LARGE INTESTINE- no digestion occurs here, water is reabsorbed

a. bacteria living here makes vitamins
b. feces is formed
c. Rectum: store feces
d. Anus: sphincter opens when stimulated by pressure; peristalsis pushes feces out-EGESTION occurs

Take a Body Quest Quiz on the Digestive System

return to Mr. Buono's syllabus