Digestion

Main Purpose of the Digestive System

• MAIN GOAL: Get usable nutrients out of our food and eliminate waste!

• Secrete enzymes into locations where digestion occurs.

• Digest (break down) food particles into smaller molecules.

• Absorb nutrients & fluids.

Nitty Gritty Terms

Intracellular Digestion:- digestion occurs within the cell

Extracellular Digestion: - digestion occurs outside of the cell in body cavities (ex: sm intestine)

Mechanical Digestion:- changing the size or shape of foods

Chemical Digestion:- changing the chemical composition of foods (ex: converting a protein into several amino acids)

Parts is Parts…Mouth

Salivary Glands

Esophagus

Liver

Gall Bladder

Stomach

Pancreas

Small Intestine Large Intestine

Rectum

Anus

Appendix

Mouth• Teeth

– Mechanical Digestion (Physically breakdown food)

• Tongue– Helps mix food w/ saliva– Aids in swallowing

Salivary Glands• Salivary Glands

– Produce saliva which is water and enzymes.

– The water aids in mechanical digestion of all foods.

– Salivary Amylase is the enzyme found in saliva. It digests complex carbs into glucose. This is chemical digestion.

Esophagus• Muscular tube that connects the

mouth & stomach• Peristalsis is a wave-like

contraction of muscles.• Peristalsis moves food from mouth

to stomach even if you are standing on your head!

Peristalsis YouTube Clip

Stomach• Muscular sac about the size of your fist.• Has a mucus lining to protect from HCl

burns.• High acidity of gastric fluid denatures

proteins & exposes peptide bonds• Mixes food, enzymes (pepsin), and HCl

with muscular contractions.– Chemical digestion of protein– Mechanical digestion of all

Small Intestine• Contains intestinal glands that

secrete digestive enzymes.• Most digestions occurs here and all is

completed here.• Site of nutrient & vitamin absorption• Has villi which are small finger like

projections that increase surface area for absorption of nutrients.

Small Intestine…a bit

more!Roughage: Foods that are coarse and not readily digestible by humans that promotes “normal bowel function”

in other words….it is like a brillo pad for our intestines!!

Fruits, veggies and whole grains provide excellent roughage! You

never want “irregular poop”…especially climbing a mountain!

Large Intestine• Short tube w/ wider diameter.

• No digestion occurs here.• Function is water absorption.• Waste moves via peristalsis.

Rectum• Lower end of large intestine.• Semi-solid waste (feces) stay here

until egested via the anus.

WHY?

Accessory Organs:

These are organs that aid in digestions but do not touch

food.Salivary Glands: produce salivawhich contains water and Salivary Amylase.Salivary Amylase is an___________ that digests___________________.

enzymecarbohydrates

Accessory Organs, con’t• Pancreas: produces enzymes that digest every

type of nutrient.• These enzymes are called proteases, amylases

and lipases. What does each digest?• The enzymes are secreted into the small

intestine.

Accessory Organs, con’t• Liver: produces bile.

– Bile is an emulsifier. It does NOT digest fats, but rather breaks them into smaller “globs”. These smaller globs have more surface area for enzymes to do their jobs.

Gall Bladder: stores bile and secretes it into the small intestine.

Summary of Digestive Fun!Name of Organ Makes

Enzymes? Y or N

Touches food?

Y or N

Chemical made there? Nutrient acted upon?

Mouth No Yes None All - M

Salivary Glands Yes No Saliva, Salivary Amylase All – M, Carbs - C

Esophagus No Yes None None

Stomach Yes Yes HCl, Pepsin All – M, Protein - C

Sm. Intestine Yes Yes Enzymes All - C

Large Intestine No Yes None None

Liver NO No Bile Fats - M

Pancreas Yes No Lipase, Amylase, Protease All - C

Gall Bladder No No None None

Disorders of the Digestive System

Gall StonesGall Stones are small, hard particles usually of cholesterol which block the bile ducts.

OMG!

Ulcers:

Damage to the stomach wall due to the mucus lining thinning or being destroyed and the HCl acid burning the muscles of the wall.

Constipation:Feces (poopie) is too hard because too much water has been

removed. “Nuggets” are too hard and dry to pass smoothly through the rectum and anus!

Don’t strain! It’ll give you hemorrhoids!

Diarrhea:

Feces (again…poopie) has too much water due to the large intestine not reabsorbing enough resulting in runny…or really runny poo.

Any DISEASE or DISORDER is considered a disruption of…

HOMEOSTASIS (also called

DYNAMIC EQUILLIBRIUM)