Digestive System

Vocabulary

• __________ - life function by which humans use for energy, growth, and repair

• ___________- mouth • ___________- wave of muscular contractions• __________- microscopic parts that help with

absorption in the small intestine• ____________- bile movements (semi solid

stored in rectum)• _____________ - splitting by adding water

(break down od big pieces into smaller ones)

Let’s Review

• One of the Life Process that are similar in ALL Living things is nutrition. – Nutrition is needed for growth, repair, and

energy. – In order for us to us nutrition we need to break

down the nutrients into small enough pieces that they can reach each cell.

– Our bodies need a healthy diet this includes the right amount of protein, carbs, fats, and minerals

So how do we get these nutrients in our bodies?

I Don’t know!!! Let me sleep!

OOOOHHHH. I

know….Digestive System

Digestive System Overview

• There are four parts to digestion

1. __________- taking in food

2. ___________- mechanical and chemical breakdown of food so that it can be absorbed by the cells

3. ______________: cells lining the digestive tract take up (absorb) small nutrient molecules

4. ________________: undigested material passes out of the digestive tract

There are two ways digestion breaks up the food

• 1. Mechanical digestion – physical breakdown of large pieces of food into smaller ones

• 2. Chemical digestion – hydrolysis – the splitting of large molecules into small, molecules with the use of water and enzymes ( in other words; breaking complex molecules into simple ones)

The process of chemical digestion ( hydrolysis) is controlled by enzymes

Examples of Chemical Digestion:

• 1. Carbohydrates+ water -> simple sugars (glucose for instance)

• 2. Proteins+ water -> amino acids

• 3. Lipids+ water -> 3 fatty acids +gylcerol

How Does Our Digestive system

work?

HUMAN DIGESTIVE SYSTEM

• The digestive system is a one way food tube that goes from the Oral Cavity to the rectum.

• This one way track is called the GI track (gastrointestinal)

Oral Cavity

• Oral Cavity is a fancy name for a mouth– Used to ingest (take in

food)

• Teeth - function in mechanical breakdown of food, increases surface area of food for enzyme action

• Tongue -

Teeth &Tongue

• Teeth - function in mechanical breakdown of food, increases surface area of food for enzyme action

• Tongue acts as a plunger to push food back into the throat (pharynx) taste buds are located on the surface of the tongue

• The enzyme reaction is caused by saliva

• Saliva is secreted (let out) by the salivary glands

• The saliva’s job is to begin the Chemical digestion of carbohydrates etc..

Pharynx

• Pharynx is another name for the throat – The tongue pushes

the food to the back of the throat

• This starts the swallowing

• food is now in the form of a bolus

– Epiglottis: flap that prevents choking

Esophagus

• Esophagus: muscular tube that moves food from mouth to the stomach by process of peristalsis: wave of muscular contractions that moves chewed food to stomach

Stomach

• Stomach: J-shaped, sac-like , muscular organ

• mechanically churns food into a liquid and begins chemical digestion

• lining secretes gastric juice,

• stomach empties in about 2-6hrs.,

• food now liquid called chyme

Gastric Juice

• Components of gastric juice:– 1. water-solvent– 2. mucus-lubrication– 3. enzyme that begins chemical digestion of

protein– 4. hydrochloric acid (HCl)

Small Intestine • the major organ of chemical digestion

and nutrient absorption,• long twisted tube with small diameter, • enzymes and fluids needed to

complete chemical digestion come 3 separate sources:

– 1. intestine itself– 2. pancreas-. Small intestine– 3. liver-> gallbladder->small intestine

• Main organ for absorption

• Villi: fingerlike projections that increase surface area of small intestine contain a network of capillaries for absorption of amino acids and simple sugars into blood, center contains lymph vessel called lacteal which absorbs fatty acids

Large Intestine

• The food now goes into the large intestine – It gets the food that has

not been digested – Usually in a liquid state – NO digestion occurs here – Reabsorbs the water and

solidifies the waste – known as feces

• the feces are stored at the lower end of the Long Intestine called the rectum

– Leaves the body through the anus

Accessory Organs to the digestive system

• Even though not part of the food tube there are important organs for digestion

• This includes – Liver – Gallbladder – Pancreas

Liver

• largest internal organ (has many functions outside digestion)– Makes bile ~ bile NOT

an enzyme,) • Bile breaks down

lipids- breaks them into smaller droplets to increase the surface area for enzymes (lipases) to act on fats

Gallbladder

• small storage sac for bile, carries bile to small intestine

Pancreas

• Pancreas: located near small intestine– Produces juices, enzymes,

and fluids• These enzymes are

important to break down complex molecules into soluble end products

– Such as » Glucose » Amino acids » Fatty acids » Glycerol

Digestive Homeostasis Disorders

• 1.Constipation– person has uncomfortable or infrequent bowel movements results from sluggish peristalsis that allows excess water to be removed from feces (fecal matter hardens)- may result from insufficient fiber in diet

• 2. Diarrhea– opposite of constipation– associated with intestinal disturbances caused by infections or stress– prolonged diarrhea may result in severe dehydration

• 3. Gall stones– small hard particles made of cholesterol which form & collect in gall bladder- may block the bile duct and cause pain

• 4. acid reflux -backflow of stomach contents upward into esophagus

• 5. appendicitis- inflammation of appendix