Biology 1012: Chapter 43: Animal Nutrition - Part II
The Digestive System (continued)
Exiting the stomach
Pyloric Sphincter Relaxes (slightly)
Peristalsis pushes stomach contents to duodenum.
How is acid neutralized?
The Small Intestine
Basic Structure
· Lumen
· Villi
o Capillaries
o Lacteal
· Micro villi
How much surface area is in small intestine?
Protein Digestion
Stomach (Beaumont)
HCl
Denatures proteins
Pepsin
Cleaves peptides from proteins
Pancreatic Proteases
Cleave amino acids form peptides
Activation of Intestinal Proteases
How does the digestive system know WHEN to release secretions?
Nerves
Hormones
Secretin
Other Hormones Controlling Digestion
Cholecystokinin (CCK)
source - duodenum
effect: gall bladder releases bile
Enterogastrone
source: duodenum
effect: inhibits peristalsis
Gastrin
source: - stomach (G cells)
effect: release of HCl and pepsinogen
Lipid Digestion
Bile salts emulsify
Lipase
Carbohydrate Digestion
Salivary Amylase
Pancreatic Amylase
Carbohydrate broken into monosaccharides
Glucose Absorption
Na+/Glucose Cotransporter into intestinal lining
Glucose diffuses into capillary
Water follows by osmosis
Large Intestine
Appendix (caecum)
Colon
water re-absorption
Aquaporins (water channels)
salt excretion
Feces
Rectum
2 sphincters
Glucose Homeostasis
Glucose Glycogen
Hormones: Insulin and Glucogon
Make sure you know how this cycle works.
Diabetes Mellitus
Type I: Cant Synthesize insulin
Type II: Defective insulin receptors
Glucose-starved cells consume their own proteins.
Tissues waste away
Leading cause of:
kidney failure, blindness, and amputation
Link between obesity and Diabetes
Whats the cause?