Difference between mechanical and chemical

1

• Difference between mechanical and chemical?
• - Mechanical- breakdown of food by churn or chew
• - Chemical- breakdown of food by enzymes or
  chemicals
• What is an enzyme? Works on specific
  biomolecules (a biomolecule would be a carb,
  protein or fat)
• - speeds up reaction
• - is a protein

2

• Your digestive tract is approximately 9 meters
  (30 feet) in length, open at both ends.
• The large intestine is about 1.5 meters (5 feet)
  long and 6.5 centimeters (2.5 inches) in
  diameter.
• The small intestine is approximately 3 meters (12
  feet) long and 2.5 centimeters (1 inch) in
  diameter in a living person. The small intestine
  will measure nearly twice this length in a
  cadaver when the muscle wall is relaxed

3

• The average human produces 25,000 quarts of
  saliva in a lifetime, enough to fill two swimming
  pool
• Enzymes in saliva only digest starchy foods

4
Mouth

• Digestion mechanical and chemical
• Enzymes salivary amylase (breaks down carbs
  into simple sugars)
• Food when leaves mouth a mushy ball (bolus)

5

• It takes 4 to 8 seconds for food to travel from
  your mouth to your stomach

6
Esophagus

• Takes food from mouth to stomach
• Why does it go down esophagus?
• When you swallow, your epiglottis blocks food
  from traveling down your trachea
• How does food travel down esophagus?
• Peristalsis- waves of muscular contractions that
  moves bolus down
• What controls passage of food from the esophagus
  into the stomach?
• Lower esophagal sphinctor

7

• The stomach can stretch to 50 times its empty
  size and hold about 4.5 quart
• Without enzymes in your stomach, it would take 50
  years to digest a single meal
• Every minute, about one half million damaged
  cells that line the stomach are replace

8
Stomach grinds, digests and stores food for
later digestion

• Type of digestion?
• Mechanical and chemical
• Chemicals present to aid digestion?
• Gastric juice HCl (hydrochloric acid) and
  Pepsin (enzyme that breaks down proteins into
  amino acids)
• What form is food in when it leaves?
• Liquid called chyme
• What controls passage of food?
• Pyloric sphinctor

9

• Water molecules in the gut move at 1,500 miles
  per hour
• Vomiting can empty not only the stomach, but also
  the first foot or so of the small intestine

10
Small Intestine Most absorption and digestion
occurs here

• - 3 main parts?
• duodenum, jejugnum, ileum
• - Type of digestion?
• chemical
• Chemicals present?
• Protease- breaks down proteins
• Lipase and bile - breaks down lipids
• Pancreatic amylase- breaks down carbs
• Purpose of villi?
• Increase surface area of small intestine for
  absorption

11
Small intestine contd

• 3 ways in which small intestine is ideally
  designed
• Villi
• Length
• Folds/surface area

12
(No Transcript)
13

• Human feces is normally 25 dead intestinal
  bacteria

14
Large Intestine

• Reabsorbs water, vitamins/minerals are absorbed
• Rectum- stores feces until it can be eliminated
  through the anus (rectum is just an extension of
  the large intestine, the anus is the opening of
  anal canal to outside
• 3 main functions of large intestine
• Reabsorb water
• Absorb vitamins/minerals
• Produce/store waste

15
Accessory Organs and glands delivers digestive
juices to differents parts of digestive system

• Salivary glands- secrete salivary amylase to
  mouth
• Pancreas- releases digesting enzymes to small
  intestine- pancreatic lipase, pancreatic amylase,
  pancreatic protease
• Liver- produces bile (digests fats) and
  breakdowns toxins
• Gall bladder- stores bile which is then emptied
  into small intestine

16

• This is where the salivary glands are

17

• Location where most absorption and digestion take
  place

18

• At this place, only proteins are digested

19

• Stores bile and empties it in small intestine

20

• The first place that carbohydrates are broken down

21

• This is where reabsorption of water takes place

22

• Makes salivary amylase

23

• Connects the mouth to the stomach

24

• This is where peristalsis occurs

25

• Makes lipase, amylase and protease and releases
  it into the small intestine

26

• This is where the juice is, gastric juice that is
  (pepsin and HCl)

27

• This is where vitamins and minerals are absorbed

28

• This burns when acid from the stomach moves upward

29

• This where the feces are stored until they are
  eliminated from the body

30

• At this place, proteins, lipids, and
  carbohydrates are broken down

31

• Without this, you wouldnt be able to make the
  bolus

32

• Produces bile and breaks down toxins

33

• In this area, you will find villi