1. Digestion & Absorption
HLTH 120 N: Lecture 3

2. Objectives Distinguish between appetite and hunger
Identify differences between digestion & absorption
Know the GI organs & how they contribute to digestion, absorption and elimination
Know key enzymes & their role in digestion
Identify major hormones involved in GI regulation
Describe the 4 types of absorption
Explain the structural characteristics of and function of the small intestines lining
Recognize GI diseases & disorders covered in class

3. What’s the Difference?
Hunger
Appetite

4. How is hunger regulated?
The _____________ is signaled by nerve cells and hormones that respond to organs
Nerve cells
Hunger hormones
Respond to blood sugar: ____________________
Give feelings of satiety: leptin, CCK, serotonin
Satiety

5. The fate of food Digestion: Absorption:
Elimination: undigested food & waste are excreted

6. Digestion starts in the mouth
Chewing is
Saliva begins
Amylase -
Bicarbonate neutralizes acids
Food travels as down the ___________ through ____________ (waves of muscular contraction)
Released to the by the esophageal sphincter

7. The stomach Here food is mixed, digested & stored
Gastric glands secrete gastric juices
HCL:
Pepsin:
Gastric Lipase:
Mucous:
Intrinsic Factor: binds to B12
Absorbed:
Food is mixed into chyme which is stored until release by the pyloric sphincter

8. Intestines Small Intestine Large Intestine
3 sections- Duodenum, Jejunum, Ileum
Further breakdown of nutrients
Main role:
Large Intestine
Stores waste ( , toxins, bacteria & water) for excretion

9. Enzymes break food into molecules
Chemical Digestion
Enzymes break food into molecules
Digestive Enzymes Produced in the GI tract
Organ
Enzyme
Action
Mouth
Salivary Amylase
Stomach
Pepsin
Gastric Lipase
Pancreas
Proteases
Pancreatic lipase
Pancreatic amylase
Small Intestine
(enzymes discussed in lecture 4)
Lipase
Sucrase
Maltase
Lactase
Digests sucrose
Digests maltose
Digests lactose

10. Chemical Digestion
Hormones are messengers that send signals to help regulate digestion
They bind to proteins on specific cells to signal a cascade of events

11. Small Intestine Main function is _____________
Large surface area due to its lining:
Villi are
are absorptive cells lining the villi
Lined with projections called
Capillaries and a lacteal are inside each villus
The brush border is composed of microvilli, which greatly increase the surface area

13. Absorption Passive Diffusion: Facilitated Diffusion: Active Transport:
Endocytosis: nutrient is engulfed by the cell membrane
Blood: carries most nutrients
Lymph: carrise most lipids & fat soluble vitamins

14. Absorption Pathways

15. Accessory Organs Pancreas Liver Gallbladder Produces bicarbonate to…
Secretes amylase, lipase & proteases
Secretes insulin & glucagon
Liver
Synthesizes chemicals like bile, aiding fat digestion
Receives products from the portal vein for storage
Blood functions: releases nutrients to blood & filters
Gallbladder
CCK signals release of bile into duodenum

16. GI Disorders
Neuromuscular dysfunction, allergies & intolerances, hormonal imbalance
Belching & Flatulance

17. Heartburn & GERD Heartburn Treatment GERD: painful, chronic heartburn
Excessive HCl
Gastroesophogeal sphincter opens too soon
Treatment
OTC antacids
Swallowing food/air
GERD: painful, chronic heartburn
Over-relaxed or damaged sphincter

18. Ulcers Peptic ulcers: leroded by HCL & pepsin
Most common from: helicobacter pylori
Less common: NSAIDS

19. Food reactions Food Intolerance: Food Allergy: Celiac Disease:
Hypersensitivity reaction of the immune system
Reactions:
Celiac Disease:
Inability to process ___________, causing destruction of intestinal villi & malnutrition
Eliminate wheat, barley, rye

20. Inflammatory Disorders
Crohn’s Disease
Diarrhea, abdominal pain, rectal bleeding, malnutrition & weight loss
How can this impact a child?
Treated with medication, nutrition, surgery
Ulcerative Colitis
Similar to crohn’s disease
Limited to the colon’s inner lining

21. Functional Disorders Diarrhea Constipation
Acute if lasting less than ____________
Chronic has many causes
Treat immediately to avoid dehydration
Constipation
Absence of bowel movement for longer than normal
Nervous System, change in schedule/diet/meds
Irritable Bowel Syndrome (IBS)
Cramps, bloating, diarrhea and/or constipation
Certain foods, interrupted signaling, immunity, etc.

22. Diet Analysis Project: Part 1
Log your food/beverage intake and physical activity for 3 days
2 week days
1 weekend day
Be accurate and specific
I will not be judging your intake! You will be graded on completion of the entire project at the end of the semester