1. Lecture 2c 19 September 2016 Ingestion Digestion Absorption Metabolism
Transport
Excretion
Common digestive tract problems

2. 8) common digestive tract disorders -dysregulation of IDATME
Overview of lecture 2c
1) ingestion
2) digestion
3) absorption
4) transport
5) metabolism
6) excretion
7) regulation of IDATME
8) common digestive tract disorders -dysregulation of IDATME
   

3. INGESTION
Mouth-open, chew and swallow
Tube feeding
c) IV and catheter

4. DIGESTION a) Sequencing of events b) Digestion
-process by which food is broken down into absorbable units
-anatomy
-function of each of anatomical parts-figure 3-1 Rolfes et al
-mechanics
-muscular action of digestion peristalsis
-stomach action
-segmentation
-sphincters
-secretions of digestion

5. Figure 3.1: The Gastrointestinal Tract.
Fig. 3-1, p. 71

6. digestive glands/secretions (enzymes)
-saliva
-gastric – water, HCl and pepsin-proteins
-pancreatic juice/intestinal enzymes
carbohydrases
lipases
proteases
summary of
digestive secretions-pg 74-76

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8. Absorption
1) define-passage of nutrients from gi tract into blood or lymph
A) simple diffusion-water small lipids/fat soluble
vitamins
B) facilitated diffusion-fructose/water soluble vitamins
C) active transport-glucose/amino acids
do not confuse active transport with the transport discussed below
2) anatomy-goblet cells/crypts/villi and microvilli

9. Figure 3.9: The Small Intestinal Villi.
Absorption of nutrients into intestinal cells typically occurs by simple diffusion or active transport.
Fig. 3-10, p. 79

10. Transport
defined
getting nutrients, via blood or lymphatic systems,
to where needed (W)
when needed (W)
in the form needed (F)
and in the correct quantities needed (Q)
WWFQ

11. anatomy of transport
two routes
-blood and lymph

12. Anatomy
BLOOD ROUTE
Heart to artery to capillaries (intestine) to vein to capillaries (liver)–in liver get detoxification and preparation of nutrients for body use-vein to heart from liver for distribution to the rest of the body .
water soluble nutrients and smaller products of fat digestion go this route

13. Lymph route
Lymph (tissue spaces to blood)
intestine to heart directly for
distribution to rest of body
-larger fat digestion products and fat soluble vitamins (ADEK) use this route

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15. Metabolism
Building up - requires energy
Tearing down- gives energy
Tearing down-provides building blocks to build up
-also leads to excretion

16. Excretion-in whole or as a metabolite
-urine-protein (urea), minerals, water,
carbohydrate, vitamins
-feces-carbohydrates, lipid, vitamins, protein,
water, minerals
-sweat-minerals,water
-saliva?-minerals?, carbohydrates?,
lipids?, protein?, water?,
vitamins?
-breathing-O2 and CO2

17. Regulation of IDATME-pgs 83-86 Rolfes et al.
-all hinges on homeostasis
homeostasis-maintenance of constant internal
conditions
homeostasis can be disrupted by physical immaturity,
aging, illness, nutrition
-stomach pH homeostasis – pH 1.5-hormonal
regulation-important
for digestion

18. function Regulation of IDATME Digestion regulation Pyloric sphincter
hold food ready for duodenum
duodenum has pH sensors
-too acid-close pyloric sphincter
and bicarbonate added to chyme
making chyme neutral and then
pyloric sphincter opens again
why? -pH important for enzyme
function

19. Regulation of IDATME
Digestion regulation continued
hormonal regulation of 3 types of
enzymes- type and amount of enzymes
from pancreas
bile-fat emulsion-amount under hormonal regulation
fat slows peristalsis-hormonal
digestion regulation
leads to absorption regulation
leads to
transport regulation

20. Regulation of IDATME
Ingestion regulates digestion
Digestion regulates absorption
Absorption regulates transport
Transport regulates metabolism (WWFQ)
Metabolism regulates excretion

21. Common digestive problems
choking- epiglottis-tough meats, hot dogs, nuts, grapes
carrots, hard candies, popcorn and
peanut butter
vomiting-cause-gastric irritation
-effects are : dehydration
: nutrient loss (salts)
: teeth damage if excessive
(bulimia)
: aspiration
-solution-replace salts/fluids by oral or IV
diarrhea-cause-infection, drugs, sorbitol, olestra, colitis
-effects-if not reversed get dehydration and nutrient loss
-solutions-oral or IV replacement of fluid and nutrients with low fat small meals
and a gradual increase in fibre

22. Common digestive problems
constipation-cause-failure to respond to defecation
signal
-lack of activity (intestinal muscle tone)
-medications
-tumours
-solution-eat fibre(eg prunes)- attracts water
-drink more water
-eat fat- bile produced-attracts water
belching -cause-swallowing air, gallbladder disease or
peptic ulcer
-solution-medical treatment of cause
gas-cause-carbohydrate rich diet with partial digestion of fibre in
gut and rest goes to bacteria that make gas
-solution-change diet

23. Common digestive problems
heartburn and acid indigestion
cause-acid reflux-anatomical defect
-eat or drink too much
-chew too little
-smoking
-solution- if not an anatomical defect eliminate other causes
ulcers-gastric or peptic (duodenal)-cell erosion
-cause-not stress or spicy foods
-H. pylori story
-AIDS drugs
-solution-avoid pertinent infections

24. disorders causing excessive gastric acid secretion
treat via- antibiotics
- withdrawl of offending
foods
-withdrawal of caffeine or
alcohol on a
case by case basis

25. Next lecture
Carbohydrates-structure and classification
-IDATME of carbohydrate