1. Digestion – “How do we acquire…”

2. Diary of a toast you are about to eat
Mouth
Anus
Mouth
Epiglottis
large intestine
Esophagus
pyloric sphincter
cardiac sphincter
stomach
small intestine
tongue
pharynx
rectum
anus

3. Two modes of digestion Mechanical Chemical
Breaking down of food physically
Increases Surface area
Chemical
Enzymes break down organic molecules into smaller pieces
Use two different colours to label where these two modes of digestion occur

4. Job of Salivary glands Three pairs of salivary glands secrete juices
Sides of the face: below & in front of the ears
Ducts open on the inner surface of cheek
Beneath the tongue
Beneath the floor of oral cavity
Ducts open under the tongue
Saliva contains salivary amylase
Starts to break down starch

5. Chewing & swallowing in detail
In the Pharynx: food & air passage cross
Trachea in front of esophagus
Swallowing = reflex action (done without conscious thought)
To stop food going up the nose: Soft palate moves back to close off the nasopharynx
To stop food going into the lungs: Trachea moves up under the epiglottis to cover the glottis (opening to voice box/”larynx”)
Swallowing & breathing does not occur simultaneously

7. Job of the Esophagus Transfer food from mouth to stomach
“Sphincters” = muscles encircling tubes that can act as valves
Heartburn = when stomach contents escape into the esophagus
Vomiting = abs (abdominal muscles) & diaphragm propels stomach contents up

8. Job of the Stomach (“gastric”)
25cm (10 inches) in length
Can hold up to 4 liters!!!
Both Mechanical & Chemical digestion:
Muscular wall – churns to mix food with gastric juice
Produces juices – gastric glands produce gastric juice
Empties in about 2-6 hours

9. Entrance & Exit Doors of the Stomach

10. Job of the Stomach (“gastric”)
Pepsinogen
Turns into pepsin with help of HCl
Hydrochloric acid / HCl
Kills most of the bacteria at pH 2
Breaks down connective tissue of meat
Mucus
Think layer of mucus protects wall

11. What do these organs look like in real life?
Look at the microscopic slides of:
Salivary glands
Esophagus
Stomach
Draw what you see
Label parts using the internet/textbook
Relate structure to function

14. Job of the Small Intestine
Smaller diameter than the large intestine
Length?
6 meters (18 ft) in length
“Duodenum” = first 25cm of small intestine
Receives Bile from Liver
Receives Pancreatic juice from the Pancreas
Full of villi: microscopic extensions called microvilli
Absorbs nutrients

15. Villus in detail Blood capillaries absorbs sugars and amino acids
Lacteal absorbs lipoprotein droplets
Glycerol & fatty acids enter epithelial cells / lining where they are packaged into lipoprotein droplets

16. Job of the Large Intestine
Larger in diameter than the small intestine
Absorbs water, salts and some vitamins
Stores indigestible material
Bacteria living in it break down indigestible material & produce some vitamins (i.e. vitamin K = important for blood clotting)
Bacteria from yogurt can increase the amount of bacteria living here

17. Large Intestine in detail

18. Poop ¾ Water ¼ Solids (Bacteria, fiber, other indigestible materials)
BROWN because of broken down bilirubin (breakdown product of hemoglobin) & oxidized iron in hemoglobin
¾ Water
¼ Solids (Bacteria, fiber, other indigestible materials)
Bacteria reacting with indigestible materials cause FART and SMELLY POOP
“Defecation Reflex:” stretching of rectum wall → Nerve impulses to spinal cord → Contraction of rectal muscle & Relaxation of internal anal sphincters

19. Other Poops
Diarrhea
Infection of the lower intestinal tract: Increase in peristalsis
Water not absorbed
Nervous stimulation
2. Constipation
Inhibition of defecation

20. What do these organs look like in real life?
Look at the microscopic slides of:
Duodenum
Small intestines
Large intestines
Draw what you see. Is there a significant difference among the three parts?
Label parts using the internet/textbook
Relate structure to function