In order for your body to get energy the food we eat must pass through the digestive system It is in charge of breaking down food into small enough parts to be used by cells
Take the crackers you have in front of you and chew them up well..BUT DO NOT SWALLOW THEM!!!! Hold them in your mouth for 5 minutes….starting…. Answer the questions as you go.
How did the crackers taste as you first chewed them?
Describe how the taste changed as you neared the 5-minute mark?
What do you think caused the any changes you experienced?
Mechanical – the physical breakdown of food into very small pieces Chemical – breakdown of large particles into smaller particles using ENZYMES.
The digestive system is merely a pathway where food follows long tubes with a few compartments It starts at the mouth and finishes in the rectum
This is the first stage of digestion that occurs in this pathway Mechanical digestion occurs with the chewing of the food using teeth Saliva in the mouth moistens food and adds an enzyme called salivary amylase.
When your food is fully chewed your tongue pushes it to the back of your throat Swallowing pushes the food down your throat into your esophagus The food is pushed towards your stomach by wave-like movement called Peristalsis They are caused by the contracting and relaxing of muscle tissue around the esophagus
Deals with the arriving food with a few processes; ◦ The muscular stomach wall churns food back and forth ◦ This mixes the food with the secretions from the wall of the stomach, called GASTRIC JUICE
Gastric Juice is made up of ◦ Mucus ◦ Hydrochloric Acid ◦ Water ◦ Digestive Enzymes
The Hydrochloric Acid and enzymes help chemically breakdown the larger particles The mucus helps prevent the gastric juices from digesting the stomach itself The stomach slowly releases the food, which is now a liquid, into the small intestines
The average length of an adult human male is about 22 feet 6 inches or 6.9 meters In women it is 23 feet 4 inches or 7.1 meters
Chemical digestion continues in the small intestines The PANCREAS sends in more digestive enzymes to further help the breakdown The small intestines itself releases more enzymes to assist the pancreas
Once the food has been broken up the small intestines absorbs as much as it can To catch as much as possible the intestines use VILLI – finger like projections that absorb nutrients The absorbed nutrients go directly into the blood stream
The liver produces BILE Bile is stored in the GALL BLADDER The gall bladder sends bile into the small intestines to assist in more chemical digestion
When food reaches large intestines mechanical and chemical digestion is complete They absorb water, vitamins and minerals Whatever is left forms into feces and is stored in the rectum