Digestive System

Macronutrients (macromolecules):

1. ·Carbohydrates: provide sources of glucose needed for cellular respiration (energy)•sources: breads, cereal, pasta, potatoes...•glucose stored as glycogen in liver •cellulose (plant cell wall) not a human nutrient•broken down into simple sugars

Macronutrients (macromolecules):

2. ·Fats: important in cell membrane structure, surrounds organ and joints, long term energy, hormones•sources: butter, oils, animal fat•saturated fats (bad)...solid at room temp •unsaturated fats (good) ...liquid at room temp•broken down into fatty acids

Macronutrients (macromolecules):

3. ·Proteins: provide structural support; transport proteins move molecules around body (haemoglobin); enzymes speed up chemical reactions•sources: meat, fish, eggs, milk, beans, nuts...•broken down into amino acids •8 essential AAs...ingest

Micronutrients:•Vitamins: organic compounds (CHO elements) ...A,B1,C,D,E•Minerals: inorganic compounds...Calcium, iron, potassium, sodium

•Water: 70% of the body...blood (plasma)=90%- water transports soluble compounds- cooling (sweating)

pg 406#3,4,5Pg 410#1,5,11

Enzymes break down macromolecules by hydrolysis (adding a water molecule breaks bonds between subunits

4 stages of food processing:

4 stages of food processing:

1. Ingestion: the taking in of nutrients

2. Digestion: the breakdown of complex organic molecules into smaller components:•Mechanical=physically breaking molecules up...teeth•Chemical=changing the chemical structure...enzymes

3. Absorption: the taking up of digested molecules from digestive to circulatory system

4. Egestion: the removal of waste from the body

Alimentary canal: •a tube where food is processed: head --->anus•function is the same but the length varies depending on feeding habits. Why rabbit longer?

page 410#13-16

1. The Mouth•Mechanical digestion begins with the teeth physically breaking the food down (smaller to pass)•allow for a greater surface area for chemical digestion•Chemical digestion ·Salivary glands secrete enzyme: salivary amylase·breaks down starch molecules (carbs-simple sugars)·This enzyme works best at a neutral pH. ·Mucus and water added…moisten

2. Esophagus•muscular tube from mouth – stomach•epiglottis closes over the trachea when you swallow •muscle contractions of the walls of the esophagus (called peristalsis) move the food (bolus) along

3. esophageal (cardiac) sphincter•provides some involuntary control of food entering or leaving the stomach

4. Stomach mechanical digestion•through the contraction of the muscles around it•folding called rugae.

4. Stomach: Chemical Digestion

•Pepsin, an enzyme that breaks down proteins to AAs is added (inactive = needs low pH)•Food is “paste like” called chyme

•Hydrochloric acid is added•breaks down fibrous tissue•kills bacteria •lowers the pH…activates pepsin

•Is amylase still functioning??

Mucus is also added to protect the stomach lining

5. Pyloric sphincter•Controls movement of chyme into the duodenum (small intestine)

6 Small Intestine•chyme into the duodenum through pyloric sphincter•release of secretin, a hormone to the pancreas•releases sodium bicarbonate (Na2HCO3)... increases pH of the chyme to 8•activates most intestinal enzymes•pancreas (releases its enzymes: lipases, proteases, and carbohydrases)•gall bladder (stores/releases bile produced in liver)•Bile emulsifies fat (physical breakdown-breaks big blobs into little blobbies

•jejunum and ileum (SI) are primarily for absorption

•finger-like projections: villi increase the surface area for absorption of the digested nutrients•inside each villus is a capillary network for absorbing simple sugars and amino acids•central lacteal for absorbing fat particles

7. Large Intestine

•water and dissolved minerals are absorbed from the undigested food•produce vitamins B and K as waste products (absorbed)•undigersted material=feces

Accessory Organs:

•Salivary Glands: amylase and mucus

•Liver produces bile (fat breakdown...are not lipases)…detoxification (alcohol)

•Gall Bladder stores bile

•Pancreas produces and releases sodium bicarbonate and enzymes

Digestive System Disorders

Peptic ulcerCrohn's diseaseconstipationhepatitiscirrhosispage 422#19-24

endoscopesdiabetes and insulin

page 427#2,3,4,6,13,15

Digestive Review•Macronutrients (Carbohydrates, Proteins, fats);•Micronutrients (vitamins and minerals)•Enzymes, pH and control of enzyme activation•Ingestion, digestion, absorption, egestion•Mechanical and chemical digestion•Anatomy (mouth, pharynx, epiglottis, esophagus, cardiac sphincter, stomach, pyloric sphincter, duodenum, jejunum, ileum, caecum, colon, rectum, anus)•Accessory organs: pancreas, salivary glands, liver, gall bladder•Disorders: Peptic Ulcer, Cirrhosis, Hepatitis, Diabetes

Page 521#1-7,10,12,14,17-22,44,45,47,51,53,57,58,Page 526#1-3,6-10