Opening ActivityDirections:

After you eat the snack provided, write the following parts of the digestive system in the order your snack passes through your body. Do not include accessory organs within your list. Not every part will be used.

THE WINNING GROUP GETS 5 EXTRA CREDIT POINTS ON THEIR

QUIZ

• Duodenum• Pharynx• Stomach• Jejunum• Mouth• Colon

• Esophagus• Anus

• Salivary glands• Ilium

• Pancreas

The Digestive System

By: Rebecca DePalma, Elisha Son, & Connor Kuykendall

Function

Turning food into the energy you need to

survive and packaging the residue for waste

disposal

Organs of the Digestive SystemLocation and Function

Salivary Glands

MouthPharyx

Esophagus

Liver

Stomach

PancreasSmall intestine

Large intestine

RectumAnus

Gallbladder

Function: Mouth

Mechanical breakdown of food, chemical digestion of carbs

Function: Pharynx

Connects mouth to esophagus

Function: Esophagus

Peristalsis pushes food to stomach

Function: Stomach

Mixes food with secretions to begin protein digestion

Function: Small Intestine

Mixes food with pancreatic juice and bile, breakdown of food molecules

Small Intestine Breakdown

•Duodenum - fixed portion of the small intestine, first portion following the stomach; 25 cm long •Jejunum - next portion, making up 2/5 of the small intestine •Ileum - the remainder of the small intestine•Mesentery - double-layered fold of peritoneal membrane; suspends intestines from the posterior abdominal wall•Intestinal villi - tiny projections of mucous membrane, greatly increasing the surface area of the lining, aiding absorption; numerous in the duodenum

Function: Large Intestine

AKA Colon; Absorbs water and electrolytes to form feces (indigestible materials in preparation

for elimination)

Function: Rectum to Anus

Regulates elimination of feces

Accessory OrgansFunction: Salivary

Glands

Secretes saliva

Accessory OrgansFunction: Liver

Produces bile which emulsifies fat

Accessory OrgansFunction: Gallbladder

Stores bile and introduces it into the small intestine

Accessory OrgansFunction: Pancreas

Produces/secretes pancreatic juice into small intestine

Structure of Alimentary Canal•Consists of 4 distinct layers; mucosa, submucosa, muscular layer, and serosa

1. Mucosa:• Formed by surface epithelium, underlying

connective tissue, and a small amount of smooth muscle

• In certain regions, the mucosa is folded with tiny projections that extend into the passageway (lumen)

• Lumen increases absorptive surface area• Mucosa protects the tissues underneath it

and carries on secretion and absorption• Has glands that are tubular invaginations

into which the lining of the cells secrete mucus and digestive enzymes

2. Submucosa•Consists of loose connective tissue, glands, blood vessels, lymphatic vessels, and plexus•Plexus – nerves organized into a network • Its vessels nourish surrounding tissues and carry away absorbed materials

3. Muscular Layer•Produces movement of the tube•Consists of 2 layers of smooth muscle tissue + some nerves organized into a plexus•Circular fibers – fibers of the inner layer that encircle the tube•Contraction of circular fibers result in a decrease in diameter of the tube• Fiber of the outer muscular coat run lengthwise•When these longitudinal fibers contract, the tube shortens

4. Serosa•AKA serous layer•Visceral peritoneum has a serous layer, or outer covering, of the tube•The cells of the serosa protect underlying tissues•Also secretes serous fluid which moistens and lubricates the tube’s outer surface so that organs within the abdominal cavity slide freely against one another

Movements of the TubeTwo motor functions:

1. Mixing movements• occurs when smooth muscles in small segments of the tube contract rhythmically• ex: muscular contractions to mix food with digestive juices

2. Propelling movements• includes peristalsis (wavelike motion)• ring of contraction appears in the wall of the tube• pushes tubular contents ahead of it (think of it as a propeller)

Digestive Enzymes• Digestion enzymes are enzymes

that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body• Aid in the digestion of food

Digestive Enzymes cont.Where are they found?

• Stomach secreted by cells lining the stomach

• Pancreatic juice secreted by pancreatic exocrine cells

• Saliva secreted by the salivary glands

• Small and large intestinal secretions

Products of Digestion: Absorption Locations

Food:• Stomach -

enzymatic digestion of proteins

• Small Intestine -main site of

nutrientabsorption

Water:• Large Intestine -

absorbs water and electrolytes

•Vitamins & Minerals• Small intestine -

absorbs these, organic

substrates, and ions

Absorption Mechanisms• Water:

-Osmosis• Electrolytes:

-Diffusion, active transport• Monosaccharides:

-Facilitated diffusion, active transport• Fatty acids and glycerol:

-Facilitated diffusion• Amino acids:

-Active Transport

Carbohydrate Digestion To Cells

• Breaks down glycogen to glucose• Converts non-carbohydrates to glucose• Polymerizes glucose to glycogen

Protein Digestion To Cells

• Deaminates amino acids • Forms urea• Synthesizes plasma proteins• Converts certain amino acids to other amino acids

Lipid Digestion To Cells• Oxidizes fatty acids• Synthesizes lipoproteins, phospholipids, and cholesterol• Converts portions of carbohydrate and protein molecules into fats

Diseases of the System:

• Hiatal hernia:o portion of the stomach protrudes through a weakened area of the

diaphragm o results: gastric juices regurgitate into the esophagus, causing

heartburn, difficulty in swallowing, or ulceration, and blood loss • Ulcers:

o open sore in the skin or mucous membrane resulting from localized tissue breakdown

o caused by the bacteria, helicobacter pylori o cures: acid reducing drugs and antibiotics

• Tonsillitis:o infected tonsils tend to swello may swell to the point where they block the passageways of the

pharynx and interfere with breathing and swallowingo may have to get them removed if patient is non responsive to

antibiotics

Diseases of the System:

• Jaundice:o turns the skin and whites of the eyes yellowo reflects buildup of bile pigmentso obstructive jaundice: bile ducts are blockedo hepatocellular jaundice: liver is diseasedo hemolytic jaundice – red blood cells are destroyed toorapidly

• Cystic fibrosis: o abnormal chloride channels in cells in various tissues draw

water inward from interstitial spaceso dies out secretions in the lungs and pancreas, leaving a sticky

mucus behind

• Acute pancreatis: o extremely painful conditiono results from a blockage in the release of pancreatic juiceso Alcoholism, gallstones, certain infections, traumatic injuries, or

the side effects of some drugs can cause pancreatis

Nutrition• Adequate diets provide sufficient energy, essential

fatty acids, amino acids, vitamins, and minerals• Food pyramid: carbs, fruits, vegetables, protein,

dairy, fats/oils/sweets

Nutrition•Individual requirements vary based on age, sex, growth rate, levels of stress, etc...•Malnutrition – lacking essential nutrientsEx: anorexia, bulimia •Normally active people (3x per week) would need more calories than a person who doesn’t exercise at all•Your body needs to replace burned calories by obtaining more nutrients and carbs