Lecture 2c
18 September 2015
Ingestion
Digestion
Absorption
Metabolism
Transport
Excretion
Common digestive tract problems
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
INGESTION
a) Mouth-open, chew and swallow
b) Tube feeding
c) IV and catheter
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
http://nutrition.jbpub.com/resources/animations.cfm?id=1&debug=0
-sphincters
-secretions of digestion
Fig. 3-1, p. 71
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
E:\Media\Animations\chapter3\Digestive_Sandwich\0308.html
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
Fig. 3-10, p. 79
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
anatomy of transport
two routes
-blood and lymph
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
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
E:\Media\Animations\chapter3\Vascular_System\311.html
file:///E:/Media/Animations/chapter3/Vascular_System/311.html
Metabolism
Building up - requires energy
Tearing down- gives energy
Tearing down-provides building blocks to
build up
-also leads to excretion
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
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
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
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
Regulation of IDATME
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•
•
•
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Ingestion regulates digestion
Digestion regulates absorption
Absorption regulates transport
Transport regulates metabolism (WWFQ)
Metabolism regulates excretion
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
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
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 defecteliminate other causes
ulcers-gastric or peptic (duodenal)-cell erosion
-cause-not stress or spicy foods
-H. pylori story
-AIDS drugs
-solution-avoid pertinent infections
disorders causing excessive gastric acid secretion
treat via- antibiotics
- withdrawl of offending
foods
-withdrawal of caffeine
or
alcohol on a
case by case basis
Next lecture
Carbohydrates-structure and classification
-IDATME of carbohydrate