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Food and Digestion
Complete unit planner by writing today’s activities and homework in the appropriate spaces.
Answer the following question as today’s bellringer: Think back over our study of the circulatory system. It’s major purpose was to transport needed materials to cells and tissues throughout the body. How might the circulatory system and the digestive system work together to accomplish this?
Food and Digestion - Food and Energy
Carbohydrates
In addition to providing energy, carbohydrates provide the raw materials to make cell parts.
Food and Digestion - Food and Energy
Fats
Many foods contain saturated, unsaturated, and trans fats. Unsaturated fats are considered to be more healthful than saturated fats and trans fats.
Food and Digestion - Food and Energy
Proteins
Proteins are needed for tissue growth and repair. They also play an important role in chemical reactions within cells.
Food and Digestion - Food and Energy
Vitamins and Minerals
Vitamins act as helper molecules in a variety of chemical reactions in the body.
Food and Digestion - Food and Energy
Vitamins and Minerals
Nutrients that are not made by living things are called minerals.
Minerals are present in soil and are absorbed by the roots of plants.
Thus, how do you obtain minerals in your diet?
Food and Digestion - Food and Energy
Water
Water is the most important nutrient because the body’s vital processes – including chemical reactions such as the breakdown of nutrients – take place in water.
Food and Digestion - The Digestive Process Begins
Functions of the Digestive System
The digestive system has three main functions. First, it breaks down food into molecules the body can use. Then, the molecules are absorbed into the blood and carried throughout the body. Finally, wastes are eliminated from the body.
Food and Digestion - The Digestive Process Begins
Methods of the Digestion
Mechanical digestion – foods are physically broken down into smaller pieces
Chemical digestion – chemicals produced by the body break down foods into their smaller
chemical building blocks
Food and Digestion - The Digestive Process Begins
The Mouth
Both mechanical and chemical digestion begin in the mouth.
Food and Digestion - The Digestive Process Begins
The Mouth
The shape of an enzyme molecule is specific to the shape of the food molecule it breaks down. Here an enzyme breaks down a starch into sugars.
Food and Digestion
INDEPENDENT PRACTICE… Draw a Venn diagram comparing and contrasting mechanical and chemical digestion.
Food and Digestion
TICKET OUT… Which of the following activities represent mechanical digestion and which represent chemical digestion:
1. The teeth cut and grind food2. The stomach churns food3. Enzymes in saliva break down carbohydrates in food4. Enzymes break down proteins in food
Food and Digestion
Protein Digestion
A scientist performed an experiment to determine the amount of time needed to digest protein. He placed small pieces of hard-boiled egg white (a protein) in a test tube containing hydrochloric acid, water, and the enzyme pepsin. He measured the rate at which the egg white was digested over a 24-hour period. His data are recorded in the graph.
- The Digestive Process Begins
Food and Digestion
Protein Digestion
Percentage of egg white digested
Reading Graphs:
What do the values on the y-axis represent?
- The Digestive Process Begins
Food and Digestion
Protein Digestion
About 14 hours
Interpreting Data:
After about how many hours would you estimate that half of the protein was digested?
- The Digestive Process Begins
Food and Digestion
Protein Digestion
About 70%
Interpreting Data:
How much digestion occurred in 16 hours?
- The Digestive Process Begins
Food and Digestion
Protein Digestion
From 13 to 16 hours
Drawing Conclusions:
During which four-hour period did the most digestion take place?
- The Digestive Process Begins
Food and Digestion
Complete unit planner by writing today’s activities and homework in the appropriate spaces.
Answer the following question as today’s bellringer: Describe as best you can the process that turns food into nutrients that cells can use.
A Great Illustration of Digestion
Food and Digestion - The Digestive Process Begins
The Epiglottis and the EsophagusThe epiglottis is flap of cartilage located in the throat behind the tongue and in front of the larynx.
When a person swallows the epiglottis folds backward to cover the entrance of the larynx so food and liquid do not enter the windpipe and lungs.
Food and Digestion - The Digestive Process Begins
The Epiglottis and the Esophagus
The esophagus is a muscular tube that extends from the neck to the abdomen and connects the back of the throat to the stomach.
The esophagus squeezes the mass of food with rhythmic muscle contractions called peristalsis. Peristalsis forces the food into the stomach.
Peristalsis Demo
Food and Digestion - The Digestive Process Begins
The Stomach
Most mechanical digestion and some chemical digestion occur in the stomach.
Food and Digestion
“The Stomach”
Mechanical and chemical digestion takes place in the stomach.
Food is squeezed by muscular contractions.
Tiny glands in the stomach produce enzymes and acid.
Food is reduced to a soupy mixture called chyme.
- Final Digestion and Absorption
Food and Digestion - Final Digestion and Absorption
The Small Intestine
The small intestine is the part of the digestive system where most chemical digestion takes place.
Food and Digestion - Final Digestion and Absorption
The Small Intestine
Tiny finger-shaped projections called villi line the inside of the small intestine. Villi absorb nutrient molecules. The molecules pass from the villi into blood vessels.
Food and Digestion
“The Small Intestine”
Chemical digestion takes place in the small intestine.
Food mixes with enzymes and secretions.
Starches, proteins, and fats are digested chemically.
Enzymes and secretions are produced by the small intestine, liver, and pancreas.
- Final Digestion and Absorption
Food and Digestion - Final Digestion and Absorption
Most commonly known as the
colon…
The Large Intestine
Food and Digestion
Graphic Organizer
Esophagus pushes food from mouth to stomach.
In the mouth, the teeth break food into smaller pieces and saliva begins to break down starches.
Large intestine absorbs water and eliminates waste.
In the stomach, food is churned and mixed with digestive juices that break down protein.
In the small intestine, almost all chemical digestion and absorption occurs.
Food and Digestion
TICKET OUT… Identify each of the following statements as true or false…
1. Digestion begins when food reaches the stomach.2. Breaking, crushing, and mashing food is an example of chemical digestion.3. Saliva contains enzymes, which begin the chemical digestion of food.4. The esophagus connects the mouth with the small intestine directly.
