Digestive System Ass.Prof.Dr - PowerPoint Presentation

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Digestive System

Ass.Prof.Dr

. Suhad Faisal

Hatem

The digestive system is a long continuous tube extending from the mouth to the anus .The main organs that make up the digestive system are Oral cavity

Pharynx

Esophagus

Stomach

Small

and large

intestines

Anus

accessory glands

located

within the wall of the tubular portion of the digestive tract

salivary

glands

pancreas

liver

gallbladder

Functions

of the Digestive

System

Ingest

food

Break

down food into

simple nutrient molecules

Absorb

molecules into the bloodstream

Rid

the body of indigestible remains

The organs of the GI tract are lined with mucous membranes that secrete digestive enzymes and absorb nutrients. The organs are also covered by layers of muscle that enable peristalsis

Parts of the Digestive System

1-Mouth

The

digestive process begins in the mouth. Food is partly broken down by the process of

chewing

:

chew your food into pieces that are more easily digested by teethThe major salivary enzyme is amylase. It begins the chemical digestion of carbohydrates by breaking down starch into sugar.tongue : When you swallow, passes the food into your throat and into your esophagus.The tongue helps mix the food with saliva and also helps the swallow. After you swallow, the chewed food passes into the pharynx.

2-EsophagusLocated in your throat near your trachea ,the esophagus receives food from your mouth when you swallow.

The

epiglottis is a small flap that folds over your windpipe as you swallow to prevent you from

choking.

At the end of

the esophagus

, a muscle called a sphincter controls the entrance to the stomach. The sphincter opens to let food into the stomach and then closes again to prevent food from passing back into the esophagus

3-Stomachstomach is a sac-like organ in which food is further digested both mechanically and chemically that food being

mixed with

enzymes

. These

enzymes continue the process of breaking down food into a usable form. Cells in the lining of the stomach secrete a strong

1- hydrochloric acid (kill bacteria and give low acidity )

2-powerful enzymes that are responsible for the breakdown process. Main enzyme is pepsin which digest proteins.When the small intestine is empty, a sphincter opens to allow the partially digested food to enter the small intestine.

Small intestines are roughly 22 feet long. “Small” refers to its diameter, not its length.

Insides are coated with little ‘fingers’ called villi to increase surface area.

Nutrients from the food pass into the bloodstream diffuses through the small intestine walls.

Lipids are first digested here by lipase (enzyme)

Small Intestine

4-Small intestinethe small intestine is a 7 meter

long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver.

Peristalsis

also works in this organ, moving food through and mixing it with digestive juices from the pancreas and liver

.

Made up of three segments -- the

duodenum, jejunum, and ileumduodenum is the first segment of the small intestine. Most chemical digestion takes place here. Lipase ,Maltase, peptidase enzyme secreted by duodenum. In addition to bilejejunum and ileum are mainly responsible for absorption of nutrients into the bloodstream.

Ilem

action reabsorb lipids ,B12,bile salt

Contents of the small intestine start out semi-solid, and end in a liquid form after passing through the organ. Water, bile, enzymes and mucus contribute to the change in consistency

Once

the nutrients have been absorbed and the leftover-food residue liquid has passed through the small

intestine to the large intestine, or colon

the mucous membrane lining

of the

jejunum is covered with millions of microscopic, fingerlike projections called villi

.

Villi contain many capillaries, and nutrients pass from the villi into the bloodstream through the

capillaries.

About 5 feet long.

Accepts what small intestines don’t absorb.

consists

of three

parts

cecum

,

colon

,

rectum

Main Function:

Absorbs water and minerals from the waste matter.

Large Intestine

The

remaining solid wastes are called feces. Feces accumulate in the rectum,

A

sphincter controls the anus and opens to let feces

pass.

Colon The large intestine, or colon, is responsible for processing waste so that emptying the bowels is easy and convenient.

It’s

a 6-foot long muscular tube that connects the small intestine to the rectum

.

The large intestine is made up of the

cecum

, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum.Stool, or waste left over from the digestive process, is passed through the colon by means of peristalsis, first in a liquid state and ultimately in a solid form. It normally takes about 36 hours for stool to get through the colon

RectumThe rectum is a straight, 8-inch chamber that connects the colon to the anus.

The

rectum's job is to receive stool from the colon, let you know that there is stool to be evacuated (pooped out) and to hold the stool until evacuation happens.

When

anything (gas or stool) comes into the rectum, sensors send a message to the brain.

The

brain then decides if the rectal contents can be released or not.If they can, the sphincters relax and the rectum contracts, disposing its contents. If the contents cannot be disposed, the sphincter contracts and the rectum accommodates so that the sensation temporarily goes away.

Anus

The anus is the last part of the digestive tract.

It

is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external).

The

lining of the upper anus is able to detect rectal contents. It lets you know whether the contents are liquid, gas or solid

.The anus is surrounded by sphincter muscles that are important in allowing control of stool.

Function 1

. Directly affects digestion by producing bile.

Bile has digestive enzymes lipase and releases them into the small intestines for digestion.

Function 2.

Processes nutrients in the blood, filters out toxins and waste.

Drinking alcohol, drugs, or taking too many medications damages the liver.

Liver

Accessory

glands

Other organs involved in digestion include the liver, gall bladder, and pancreas. They are called accessory organs because food does not pass through them. Instead, they secrete or store substances needed for digestion.

LiverThe liver is an organ of both digestion and excretion. It produces a fluid called bile, which is secreted into the duodenum

The liver has many functions, but its main job within the digestive system is to process the nutrients

absorbed

from the small intestine.

Bile

from the liver secreted into the small intestine also plays an important role in digesting fat and some vitamins

.The liver is the body's chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals the body needs to function.The liver also detoxifies potentially harmful chemicals. It breaks down many drugs that can be toxic to the body.

a sac-like organ that stores and concentrates bile and then secretes it into

duodenum in the

small

intestine

to

help digest and

absorb fats

Produce lipase to digests lipids

bile

breaks up large globules of lipids into smaller globules that are easier for enzymes to break

down

.

Gall Bladder

Bile also reduces the acidity of food entering from the highly acidic stomach. This is important because digestive enzymes that work in the duodenum need a neutral environment.

The pancreas secretes digestive enzymes into the duodenum that break down protein, fats and carbohydrates

Neutralizes acids that enter small intestine.

The pancreas contributes to the neutral environment by secreting bicarbonate, a basic substance that neutralizes acid.

Regulates blood sugar by producing insulin.

If it doesn’t work right you develop diabetes.

Pancreas

Thank you