1. Animal Structure and Function
Digestive
Circulatory and Respiratory
Excretory
Nervous
Muscular
Endo, repro, develop
Immune

2. DIGESTIVE SYSTEM

3. “tube within a tube”
This

4. “tube within a tube”
Develops from this

5. Coelom and germ layers

6. Don’t be grossed out but…
ECTODERM
DIGESTIVE TRACT (inside tube)
MESODERM
ENDODERM

7. Purpose for digestive system
To break down food into useable nutrients that can be absorbed and transported to cells throughout body
Remember – we are heterotrophs!

8. We need…
water, salts
Vitamins and minerals – to maintain overall health
Macromolecules
Carbs for energy
Proteins for building and repairing of tissues
Lipids for stored energy source, brain development (babies), essential for fat-soluble vitamins

11. ANATOMY- know pathway food travels

12. PHYSIOLOGY of human digestive tract
Two main parts
Alimentary canal – the tube or pathway that the food travels through
Accessory glands – outside of the “tube” but aid in digestion by secreting enzymes into the tract

13. Accessory glands
Fill in the enzymes they secrete as we go through the whole process
Salivary gland –
Pancreas –
Liver –
Gall bladder –

14. Oral Cavity – physical (teeth grinding)
and chemical digestion (saliva)
Saliva = key enzyme is amylase which breaks down starch and glycogen into smaller carbs and maltose also contains:
mucin (glycoprotein to protect lining of mouth)
buffers and antibacterial agents

15. Pharynx
Pharynx – passageway for both air into lungs and food into esophagus
epiglottis – blocks trachea when swallowing so bolus (food ball) enters the esophagus

16. Esphagus peristalsis starts here
bolus must pass through the esophageal sphincter

17. Stomach
gastric juice
pepsin
mucous

18. Small Intestines – the main player

19. Inside lining of Small Intestine
MAJOR SURFACE AREA FOR MAJOR ABSORPTION!

20. Enzymes secreted into S.I.- you tell me their functions
pancreatic amylases from the pancreas
disaccharidases from the lining
trypsin and chymotrypsin from the pancreas
exopeptidases from intestinal lining
lipase from the pancreas
bile from the gall bladder

21. Control of pancreatic enzymes
Why secrete the inactive forms?
Trypsinogen
Chymostrypsinogen
HINT: once activated they break down proteins and your tissues contain a lot of…

22. Asorption of nutrients in the small intestine
capillaries receive – carbohydrates and proteins
Nutrient rich blood from S.I. is carried via hepatic portal vessel to the liver
Liver is in charge of distributing nutrients to blood (and rest of body

23. Asorption of nutrients in the small intestine
Lacteals receive – packaged lipids
These lead to the lymphatic system which carries the lipids to the heart

24. Large Intestine water reabsorption
salt excretion - if salt content is too high in blood
eliminate undigested food- feces formation and elimination

25. Large Intestine

26. Reclaiming Water in The L.I.
If lining of LI is infected with bacteria or virus – water unable to be reabsorbed so fecal material is watery =
diarrhea
If too much water is reabsorbed or sluggish peristalsis =
constipation

27. Radiological Images of GI Tract

28. Homeostasis and Control of Digestive System
Nervous system
Smelling, tasting and seeing (hearing the sizzle?) all stimulate the secretion of gastric juices

29. Negative feedback
Gastrin is secreted when food is present in the stomach
Gastrin increases the secretion of gastric juices
When the pH gets too low – gastrin secretion stops which in turn slows down gastric juice production (which caused the pH to lower in the first place)

30. Hormonal Control
PANCREAS
bicarbonate
SECRETIN

31. Hormonal Control
Bile
Pancreatic Enzymes
CCK

32. Comparative Physiology

33. HERBIVORE OR CARNIVORE?

34. Who’s GI Tract? Check text

35. The End!
Oh the pictures I could have put on this last slide!