Understanding Small Intestine Anatomy and Digestion Processes

1. Chap 22 – Digestion continued *Learning Objectives continued…

2. Review 1. How do villi & microvilli increase surface area in the small intestine? And how does that contribute to absorption of nutrients?

3. Small Intestine Specialized Structures in the Wall, pgs 799 - 801 Instructions: Do you already know what these do? Spend a few minutes reading up on & defining the following structures in your notes. Be ready to share responses with classmates. • 5 unique structures: 1. lacteals 2. intestinal crypts (or Crypts of Lieberkuhn) 3. Paneth cells 4. Peyer’s patches 5. duodenal (Brunner’s) glands

4. Small Intestine Lining & Specialized Structures

5. Small Intestine Gross Anatomy • Half the diameter of the large intestine (1.5 inches) • 11-12 ft long • Comprised of: _______ (8 ft long running from the duodenum to the ileum) _____ (12 ft long which is connected to the large intestine at the _______ valve) or area where ileum connects to large intestine • Jejunum & ileum hang in sausage-like coils held in place by _________ (supportive lining) mesentery

6. Digestion in the Small Intestine continued • Huge job remaining! • Remaining _____, ______, ____ & ______ acids must be digested • Occurs with help from liver, gallbladder, and pancreas

7. Liver, pg 802 - 805 right • The largest gland in the body • Superficially has four lobes – ________, _____, ________, and ____________. • Responsible for: • Production of _____ • Processing bloodborne nutrients • Storage of fat-soluble vitamins • Detoxification left caudate quadrate Action Item: Define “bile” now in your notes. Definition is found on page 805.

8. Bile • A yellow-green, _______ solution containing bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and electrolytes • Bile salts are cholesterol derivatives that: • Emulsify ____ • Facilitate ____ and ________ absorption • Help solubilize cholesterol • The chief bile pigment is _________, a waste product of heme bilirubin

9. Gallbladder • Thin-walled, green muscular sac on the ventral surface of the liver • _____ and concentrates bile by absorbing its water and ions • When released, bile enters the _________

10. Pancreas • Location • Lies deep to the greater curvature of the stomach • The head is encircled by the duodenum and the tail abuts the spleen • Exocrine function • Secretes pancreatic juice which breaks down all categories of foodstuff • _____ (clusters of secretory cells surrounding ducts)

11. Pancreas continued • Active enzymes secreted • Amylase (digests ______), lipases (digests ____), and nucleases (digests _____ ____) • Also bicarbonate-rich pancreatic juice (to help neutralize acids)

12. Review (Thus Far) *See handout. Complete now; will check answers after you have completed

13. Large Colon • Has three unique features: • ______ ____ – three bands of longitudinal smooth muscle in its muscularis • _______ – pocketlike sacs caused by the tone of the teniae coli • _________ ___________ – fat-filled pouches of visceral peritoneum

14. Large Intestine continued • Is subdivided into the cecum, appendix, colon, rectum, and anal canal • The saclike cecum: • Lies below the ileocecal valve in the right iliac fossa • Contains a wormlike vermiform _________ True function of appendix recently discovered: http://www.abc.net.au/news/stories/2007/10/10/2055374.htm

15. Large Intestine 101 Gross Anatomy Label ONLY structures circled in red on our practice diagram.

16. Functions of Large Intestine • Other than digestion of enteric _______, no further digestion takes place • Vitamins, water, and electrolytes are ___________ • Its major function is propulsion of fecal material • Though essential for comfort, the colon is ___ essential for life

17. Bacteria Flora of the Gut • Microorganisms perform a host of useful functions, such as ________ unused energy substrates, and _________ growth of harmful species • Release bi-products (i.e., gas) as they digest left-over food particles