Digestive system master honors 20016

 What is digestion?
 What happens to food after you swallow it?
 How does your digestive system work?
 What is the difference between mechanical and chemical digestion?
 What are the organs of the digestive system? (in order)
 How does each digestive system organ relate to each other?
 What are accessory organs? How do they contribute to the digestive
system?
 What role do enzymes play in digestion?
 What is a nutrient?
 How does your body get the necessary nutrients it needs to survive.
02/24/16 12:51cottingham

 How can the digestive system be negatively affected?
 What are some disorders that effect the digestive system?
 What foods does the USDA recommend eating?
 What is a food pyramid?
 How can what you eat help/hurt your overall health?

 Nutrition
 Roughage
 Ingestion
 Digestion -mechanical and chemical
 Egestion – defacation, feces!
 Absorption
 Tract
 Alimentary Canal
 Mouth
◦ Teeth
◦ Tongue
◦ Saliva
 Esophagus
 Peristalsis
 Epiglottis
 Stomach
◦ Cardiac and pyloric sphincter
◦ Hydrochloric acid
 Small Intestine
◦ Villi
◦ Microvilli
◦ Lacteal
 Large Intestine
◦ Colon
◦ Rectum
 Gall Bladder
 Liver
 Pancreas
 Appendix

 Nutrient – substances in foods that the human
body can digest.
◦ Uses for metabolism
 Roughage – “dietary fiber” indigestible material
that passes through the digestive system
 Needed for proper digestive muscle function.
 Proper “elimination” of food wastes.

 What are the four organic molecules?
 Carbohydrates
 Lipids
 Proteins
 Nucleic Acids
 MUST BE DIGESTED TO BE ABSORBED AND
USED BY THE DIGESTIVE SYSTEM!

 What are the three inorganic molecule that you
take in as part of food?
 Water
 Vitamins
 Minerals
 Are small molecules that can be absorbed
without needing to be digested!

Essential Vitamins and Minerals

 What are enzymes? How do they work?
 Enzymes are proteins that lower the energy of
activation and allow chemical reactions to occur
within living organisms.

 What is digestion?
 Breaking food down into smaller molecules.
 This can be done by physically pounding the molecules, or
chemically breaking the molecules apart.
 What is the medical term for anything digestive?
◦ GASTRO – Greek Origin
 What sort of molecules help with chemical
digestion?
◦ Enzymes
 Which reaction is involved in digestion, hydrolysis
or dehydration synthesis?
◦ Hydrolysis

 What is the difference between intracellular and
extracellular digestion?
 Intracellular digestion occurs within the cell. It
occurs in most plants and protists
 Extracellular digestion occurs outside of the cell.
Occurs in animals and fungi
 Comparative digestion in different animals…

1. Ingestion
2. Digestion (enzymatic hydrolysis)
3. Absorption
4. Assimilation
5. Egestion

 Physical digestion – caused by movement
 Chemical Digestion – enzymes, water, acids
 Accessory glands:
◦ Salivary glands
◦ Pancreas
◦ Liver
◦ Gallbladder

 Organs Includes:
◦ Tongue – mixes/moves chewed food
◦ Teeth – breaks food down
◦ Enzymes:
 Salivary Amylase – begins digestion of polysaccharides
(starch).
◦ Chewed and swallowed food: Bolus

 Tract – the continuous tube from the esophagus
to rectum (alimentary canal)
 Pharynx – begins digestive tract
◦ Receives air from the nasal cavities and food from the
mouth
◦ Epiglottis – prevents food from moving into the trachea
◦ Swallowing
 A reflex action
 Soft palate closes off the nasopharynx
 Trachea moves up causing the epiglottis to cover the glottis

 Muscular tube…connects mouth to stomach.
(epiglottis)
 PERISTALSIS – (rhythmic) muscular movement of
food thru the digestive tract after swallowing.
 No chemical action. No digestion.

 J – shaped muscular
organ. Thick walled
 Chemical and physical
digestion
 Sphincter – cardiac and
pyloric
 Stores food
 Begins protein
digestion.

 Stomach lining:
◦ Secretes mucous (pyloric
gland)
 Contains Gastric Glands:
◦ Secretes HCl – activates
pepsin; kills bacteria.
◦ Secretes Pepsin (gastric
protease) begins protein
digestion.
 Stomach processes food in
2-6 hours
 Semisolid food: chyme.

 Small diameter….6.5 meters long
 Some physical; mostly chemical digestion.
 Receives secretions from the liver/ gall bladder
and pancreas.
 3 sections: duodenum, jejunum, ileum
 Absorption of nutrients begins in the lining of the
small intestine.

 When food is present:
◦ Peristalsis occurs to:
 Squeeze chyme through the small intestine
 Mix chyme and enzymes
 physical digestion
 Speed up absorption – allows digested nutrients to contact
inner SI wall.
 Duodenum – most chemical digestion
 Pancreas – secretes liquid to neutralize acidic
chyme. (duct)

 Protein –
 Trypsin (pancreas) continues protein digestion.
 Peptidase (small intestine) completes protein digestion
 Fat –
 Bile – (liver) not an enzyme. Breaks down large fat molecules
– emulsify – increase surface area for enzyme action
 Lipase – (pancreas) digests fats.
 Carbohydrates
 Amylase (pancreas) continues starch digestion
 Maltase, lactase, sucrase (small intestine) completes
carbohydrate digestion (into glucose).

 Wall of the small intestine has circular folds with
fingerlike projections, called VILLI.
 The epithelial cells of each villus have extensions
called microvilli.
 Function:
◦ increase the small intestine's surface area for nutrient
absorption.
 Each Villus
 blood vessels ( amino acid, glucose, vitamin, mineral absorption)
 Lacteals ( fat absorption)

 Occurs at the cell level
 Nutrients converted into the substances the body
needs to survive….
◦ Glucose – ATP
◦ Amino Acids – Protein
◦ Fats – Cell Membranes

 Larger diameter…shorter tube (1.5m)
 Main Sections: Colon and Rectum
 No Digestion!
 Functions:
◦ Reabsorbs water.
◦ Absorption of some vitamins from intestinal bacteria (K
and B)
◦ Elimination (egestion) of Waste (Feces)

Largest gland in the body – 4 “lobes”
 Functions:
◦ Filters blood of “poisons”
◦ Maintains blood glucose levels (glycogen)
◦ Produces bile

 Attached to liver.
 Stores bile

 Produces enzymes and
hormones
 Enzymes for all major
food groups
 Enzymes travel to Sm.
Intestine through ducts.

 Constipation – condition by which feces is
eliminated infrequently and with difficulty.
 Excess removal of water
 Slow peristalsis
 Diarrhea – occurs when too little water is removed
 Often associated with infection
 Can result in severe dehydration

 Open sores on the interior
wall of the digestive tract.
 Usually in the stomach or
small intestine.
 Usually associated with the
over-production of gastric
juices.

 Infection of the appendix
 Sometimes caused by a
small blockage of feces
which causes a bacteria
buildup.
 An infected appendix that
bursts can be fatal
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 Small, hard
particles of
cholesterol that
block the bile
duct (in the gall
bladder.)

 The Wall of the Digestive Tract
◦ Muscularis-
 Two layers of smooth muscle
 Longitudinal, outer layer runs along length of gut
 Circular, inner layer encircles tube
◦ Serosa and Mucosa
 Serosa - A thin membrane lining the digestive tract –
outer
 Mucosa – lines inner digestive tract – secrete mucus

Digestive system master honors 20016

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Digestive system master honors 20016