Human Digestive System

1
Human Digestive System

• To be used with Digestive System Guided Notes
• Gaccione/Bakka
• Belleville High School

2
Nutrition

• Nutrition process by which
• organisms obtain and utilize
• their food
• Utilizing nutrition - 2 Parts
• 1. ingestion- taking in of food
• 2. digestion- mechanical and
• chemical breakdown of food
• so that it can be absorbed and
• used by the body cells

3
Types of Feeders

• Autotrophs- self feeders-make their own food.
  Example green plants

• Heterotrophs- consumers.
• Depend upon other
• organisms for their food.
• Example Giraffe

4
Types of Nutrients

• Nutrients- substances in food that organisms can
  use
• 2 types - micro macronutrients
• Micronutrients - nutrients needed in small
  amounts by an organism 
• examples
• vitamins (used as coenzymes to help enzymes)
• and minerals

5
Types of Nutrients

• macronutrients-
• nutrients needed in large amounts by an
  organism 
• Large molecules like carbohydrates, fats,
• and proteins that require digestion.

6
Carbohydrates

• Used for
• Energy or energy storage
• Should constitute 50 of the energy for the body.
• Found in fresh fruits and vegetables as well as
  whole grains, pasta rice.
• Provide a source of nondigestible materials
  (roughage or fiber)
• stimulates the muscles of the alimentary canal or
  food tube(esophagus, stomach intestines)

7
Fats

• Used for
• Energy storage
• Protection
• Insulation
• Part of cell membranes
• Fats contain more potential energy per each unit
  of their mass then any other major nutrient.

8
Proteins

• Used for
• Energy
• Growth and repair
• Cell membranes
• Muscle
• Blood (hemoglobin)
• enzymes

9
Other Molecules

• Water, vitamins, and minerals are small molecules
  that can be absorbed without digestion

10
Nutritional requirement

• Calorie used to measure the energy in foods
• Varies on different types of food
• Nutritional requirements (amount of calories
  needed) vary with the human
• 1.)  body weight
• 2.)  age 
• 3.)  activity level
• 4.)  your sex - male or female
• 5.)  natural body efficiency

11
Chemical Digestion

• Hydrolysis the splitting of large, insoluble
  molecules into small, soluble molecules with the
  addition of water
• Regulated by digestive enzymes
• Maltose water ? simple sugars (glucose)
• Starch water ? simple sugars
• Proteins water ? amino acids
• Lipids water  ? 3 fatty acids glycerol

12
Human Digestive Tract

• Human digestive tract aka Alimentary Canal
• consists of a continuous one way food tube
• Gastrointestinal Tract (GI)
• Upper GI -
• mouth, esophagus stomach
• Lower GI -
• small large intestine anus
• Peristalsis
• -- constriction of the esophagus

13
Mouth and Teeth

• Mouth ingests food
• 1minute
• Oral cavity contains the tongue, teeth, and
  salivary gland openings
• Teeth mechanically breakdown food
• increases the surface area of the food
• improves enzyme action

14
Saliva and Tongue

• Salivary glands
• secretes digestive fluid - saliva
• 2 Roles of Saliva
• 1. Provides lubrication for the chewed food
• 2. Contains the digestive enzyme amylase that
  begins the digestion of starch.
• Secretion of saliva is stimulated automatically.
• Tongue acts as a plunger to push food back
• into the throat (pharynx)

15
Esophagus and Stomach

• Esophagus 1 minute
• 10 inch long muscular tube
• its muscular walls move food from the mouth to
  the stomach by peristalsis
• Stomach 2 to 4 hours
• muscular J-shaped sac, size of your fist
• Protein(pepsin) begins its digestion here
• mixes the partially chewed food with gastric juice

16
Inside the Stomach

• Gastric juice
• Contains the following
• 1. Water solvent
• 2. Mucus lubrication
• 3. Hydrochloric acid (HCl) pH2 makes food
  acidic
• Allows the enzyme pepsin to function
• 4. Pepsin gastric protease
• Begins the digestion of protein in the stomach
• Acid Reflux Disease Pepcid AC

17
From the stomach to the SI

• Pyloric sphincter muscular valve between the
  stomach and the small intestine
• regulating the passage of the partially digested
  mass
• Food is held 2-4 hours in the stomach.
• Gastric bypass

18
Small Intestine - 12 hours

• a 20-25 foot long twisted tube of small diameter
  (about 1 inch)
• lined with enzyme secreting intestinal glands
  does most of the chemical digestion
• chemical digestion of carbohydrates, fats(lipids)
  proteins are digested in SI
• accessory structures, the liver, gall bladder and
  the pancreas, empty their secretions into the SI

19
Accessory Structures of SI

• Liver largest body organ
• digestive function is to make bile
• also produces insulin that
• breaks down glucose
• Disorder Hepatitis -
• inflammation of the liver
• transmitted by food or blood

20
Accessory Structures of SI

• Gall bladder small sac beneath the liver
  that stores bile
• Bile emulsifies fats(lipids)
• breaks down fats
• into smaller particles.
• Bile duct carries bile from
• the gall bladder to the S.I.

21
Accessory Structures of SI

• Pancreas located near the small intestine
• pancreatic juice is carried to the SI by the
  pancreatic duct
• Pancreatic juice secretes 3 enzymes that digests
• carbs, fats proteins.

22
Liver, Gallbladder, and Pancreas not part of
the alimentary canal all secrete into the small
intestine
23
Digestion and Absorption of SI

• Intestinal glands line the small intestine
• secrete intestinal juice
• Nearly all digestion occurs in the small
  intestine all digestion is completed in the SI.
  
• intestinal juice contains enzymes to breakdown
  proteins, fats, and carbohydrates

24
Absorption in the SI

• Absorption in the SI
• Absorption occurs directly through the wall into
  blood vessels, without the need for special
  adaptations.
• Villi microscopic fingerlike projections on the
  SI wall
• increase the surface area for nutrient absorption
• contain a capillary and a lymph vessel

25
Villi - a closer look
26
Absorption in the LI - 5 hours

• Large Intestine
• Averages 6 feet in length
• 2.5 inches in diameter
• Sometimes called the colon
• No digestion in the LI
• Appears as an inverted U surrounding the SI
• Undigested food and water enter the large
  intestine where water is absorbed.
•  
• Appendix vestigial organ not needed in human
  digestion
• at the beginning of the LI

27
Removal of Undigested Food

• Strong peristaltic action forces feces out
  through the rectum and the anus.
• Defecation the removal of feces

28
anus - epiglottis - large intestine - stomach -
small intestinemouth - pancreas - appendix -
esophagus - gallbladder - liver
mouth
epiglottis
esophagus
liver
stomach
gallbladder
pancreas
large intestine
small intestine
appendix
anus
29
Digestive Homeostasis Disorders

• Ulcers open sores in the lining of the stomach
  or the small intestine. Mucus normally prevents
  ulcers.
• associated with some kind of irritant or
  bacterial infection

30
Digestive Homeostasis Disorders

• Appendicitis infection and inflammation of the
  appendix

31
Digestive Homeostasis Disorders

• Gallstones small hard particles made of
  cholesterol which form and collect in the gall
  bladder
• may block the bile duct causing pain and
  discomfort
• treated by lasers or surgical removal of the gall
  bladder

32
Digestive Homeostasis Disorders

• Constipation the feces are evacuated
  infrequently and with difficulty
• Caused by sluggish peristalsis that allows excess
  water to be removed from the feces (fecal
  material hardens)
• may result from insufficient roughage in the diet

33
Constipation, cont.

• Treatment for Constipation

34
Digestive Homeostasis Disorders

• Diarrhea opposite of constipation
• - water is not absorbed by the body
• caused by infections or stress
• prolonged diarrhea severe dehydration