The digestive system
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The Digestive System. Function of the Digestive System. Breaks up food physically and chemically. Stores food for a short period of time. Absorbs the digested foods and passes them into the circulatory system. Stores and eliminates undigested food from the body. Types of Digestion.

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The Digestive System

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The digestive system

The Digestive System


Function of the digestive system

Function of the Digestive System

  • Breaks up food physically and chemically.

  • Stores food for a short period of time.

  • Absorbs the digested foods and passes them into the circulatory system.

  • Stores and eliminates undigested food from the body.


Types of digestion

Types of Digestion

  • Mechanical: The physical breakdown of food by non-enzyme means.

  • Chemical: The use of enzymes to breakdown food.

    • Changes food into aNEWand smaller substance that can travel into the cells.It is chemically different.


Enzymes

Enzymes

Enzymes have a specific

shape and can only do

one special job.

This is called the LOCK

AND KEY THEORY

because they only FIT

into one job

Enzymes work best

at a certain pH and

body temperature.

If the body gets too

hot or too cold, the

enzymes will not work

and we get sick or die


Regents question

Regents Question

Experiments revealed the following information

about a certain molecule:

— It can be broken down into amino acids.

— It can break down proteins into amino

acids.

— It is found in high concentrations in the

small intestine of humans.

This molecule is most likely

(1) an enzyme

(2) an inorganic compound

(3) a hormone

(4) an antigen


Regents answer

Regents Answer

(1) an enzyme


Parts of the digestive system

Parts of the Digestive System


Human digestion

Human Digestion

  • The Mouth

  • Esophagus

  • Stomach

  • Liver and Pancreas

  • Small Intestine

  • Large Intestine

  • Rectum

  • Anus


Mouth

Mouth

  • Both chemical and mechanical digestion occurs here.

  • The teeth and tongue will chop and mix the food.

  • The salivary glands will add enzymes to begin the chemical process.

  • The tongue will direct the moisten food into the gullet.


Esophagus

Esophagus

  • The gullet is the opening to the esophagus.

  • It is 12 inches long and connects the mouth with the stomach.

  • Contains smooth muscles which contract, pulling the food downward (peristalsis).


Stomach

Stomach

  • Stores and digests food.

  • pH of 1-2

  • Enzyme: pepsin which acts on proteins, rennin on dairy

  • HCl is needed to activate pepsin.

  • Mucus covers the inner lining to prevent the acid from eating the tissue.

  • The pylorus connects the stomach to the small intestine.


Regents question1

Regents Question

The diagram below represents two molecules

that can interact with each other to cause a biochemical process to occur in a cell.

Molecule A╞╢Molecule B

Molecules A and B most likely represent

(1) a protein and a chromosome

(2) a receptor and a hormone

(3) a carbohydrate and an amino acid

(4) an antibody and a hormone


Regents answer1

Regents Answer

(2) a receptor and a hormone


Small intestine

Small Intestine

  • It is divided into 3 parts: duodenum, jejunum, and ileum.

  • Most digestion takes place here

  • It is here that all the organic material are broken down into their monomers.

  • They are absorbed by structures called villi and sent into the blood.

  • The undigested food is passed on to the large intestine.


Liver pancreas and gall bladder

Liver, Pancreas, and Gall Bladder

  • These are accessory organs.

  • The liver produces bile which is needed to help digest fat.

  • The gall bladder stores the bile.

  • The pancreas produces enzymes need to finish digesting the main organic foods. It also produces insulin.


Large intestine

Large Intestine

  • Also known as the colon

  • Absorbs excess water from the unused food.

  • E. coli will produce vitamin K.

  • Stores solid waste in the area called the rectum.


Absorption

The small intestine is lined with villi which increase the surface area

Nutrients are absorbed into the blood through the villi and travel the body to be used by the cells

Absorption

The small intestine is longer

but thinner in diameter than

the large intestine


The digestive system

  • http://kitses.com/animation/swfs/digestion.swf


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