Unit 2

• Salivary Glands

  • Produces amylase to digest starch
  • Produces liquid to lubricate food
• Gastric Glands

  • Produces mucus to protect stomach
  • Produces pepsin to digest proteins
• Liver

  • Produces bile to emulsify fat
  • Breaks down RBCs
  • Stores excess nutrients (eg. Glucose for glucoreg.)
  • Detoxifies blood
• Gall Bladder:

  • Stores bile
• Pancreas

  • Produces digestive enzymes
  • Produces insulin (lowers) and glucagon (increases) to regulate sugar levels
  • Produces sodium bicarbonate to neutralize stomach acid
• Small Intestine

  • Duodenum
  • Jejunum
  • Ileum
• Epiglottis

  • Prevents food from entering trachea
• Ingestion

  • Taking in food
• Digestion

  • Breaking food particles so they can be transported into the blood stream
  • Complex -> small
  • Mechanical and chemical
• Absorption

  • Passing nutrients from Digestive tract -> blood stream
  • Villi in the small intestine
• Egestion

  • Elimination of undigested material
• Peristalsis

  • Wavelike contractions of muscle
  • Moves materials along alimentary canal
• Stomach Contractions

  • Mixing movements
  • via stomach muscles
• Chewing (Mastication)

  • Swallowing is easier
  • Increases surface area for digestion
• Bolus Formation

  • Tongue balls up food into a bolus
  • Pushes into back of oral cavity
• Peristalsis breaks food into smaller pieces as a side effect
• Stomach Contractions

  • Muscles mix and grind food
• Chyme

  • Bolus mixed with hydrochloric acid
  • In the stomach
• Emulsification

  • Bile rips large fat droplets into smaller pieces
  • Bile is a detergent (soap)
  • Occurs in the small intestine
• Hydrochloric acid has a pH of 2
• Mechanical Digestion

  • Process of breaking down large food particles into smaller food particles
• Chemical Digestion

  • Process by which food is chemically changed into small molecules
  • Absorbed by the small intestine
• Chemical digestion occurs b/c of enzyme action on food particles
• Enzymes

  • Proteins that change the rate of a reaction without being changed
• Lock and Key Model (eg. starch)

  • Enzyme (salivary amylase)
  • Substrate (starch) binds to the active site
  • Enzyme-subtrate complex formed
  • Products created from substrate (glucose)
  • Enzyme is unchanged
• Saliva in the Mouth

  • Saliva breaks starch down into simple sugars
  • Saliva contains amylase
• Gastric Juice in Stomach

  • Gastric glands secrete pepsin which breaks protein down
  • Pepsin works at a low pH -> stomach contains hydrochloric acid (pH 2)
• Digestive Juice in Small Intestine

  • Main site of chemical digestion
  • Enzymes made in the pancreas
  • Carbohydrases
  • Lipases
  • Proteases
• Large Intestine

  • Cecum
  • Ascending
  • Transverse
  • Descending
• Alimentary Canal|

  • Mouth
  • Esophagus
  • Cardiac sph.
  • Stomach
  • Pyloric sph.
  • Small int.
  • Large int.
  • Rectum
  • Anal sph.
  • Anus
• Factors affecting enzyme activity

  • Temp.
  • pH
  • Substrate concentration
• Denaturation occurs if temp. Is too high or too low - causes bonds within enzyme to break
• pH / temp too high or low -> enzyme denaturation
• Sodium Bicarbonate

  • Neutralizes chyme leaving the stomach
• Insulin lowers blood glucose
• Glucagon increases blood glucose
• Hypoglycemia

  • Cause: not eating
  • Change: blood sugar drops
  • Receptor: Glucoreceptors in blood vessels
  • Control Center: Hypothalamus / Pancreas
  • Effector: Pancreas (Islets of Langerhans) release glucagon
  • Change: Glucagon converts glycogen to glucose in liver
  • Normal conditions
• Hyperglycemia

  • Cause: eating
  • Change: blood sugar increases
  • Receptor: Glucoreceptors in blood vessels
  • Control Center: Hypothalamus / Pancreas
  • Effector: Pancreas (Islets of Langerhans) release insulin
  • Change: Insulin converts glucose to glycogen in liver
  • Normal conditions
• Islets of Langerhans in the pancreas release insulin and glucagon into the bloodstream
• Type 1 Diabetes

  • No insulin prod.
  • Insulin injections