Lecture 2c 16 January 2015

IngestionDigestionAbsorptionMetabolismTransportExcretionCommon digestive tract problems

   

Overview of lecture 2c

1) ingestion 2) digestion3) absorption4) transport5) metabolism6) excretion7) regulation of IDATME8) common digestive tract disorders

-dysregulation of IDATME

INGESTION

a) Mouth-open, chew and swallow

b) Tube feeding c) IV and catheter

DIGESTIONa) Sequencing of eventsb) 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

carbohydraseslipasesproteases

summary of digestive secretions-pg 74-76

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Absorption

1) define-passage of nutrients from gi tract into blood or lymph

A) simple diffusion-water small lipids/fat solublevitamins

B) facilitated diffusion-fructose/water soluble vitamins

C) active transport-glucose/amino acidsdo 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

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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 homeostasishomeostasis-maintenance of constant internal conditionshomeostasis can be disrupted by physical immaturity,

aging, illness, nutrition

-stomach pH homeostasis – pH 1.5-hormonalregulation-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 chymemaking chyme neutral and thenpyloric 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 enzymesfrom pancreas

bile-fat emulsion-amount under hormonal regulation

fat slows peristalsis-hormonal

digestion regulation leads to absorption regulation

leads totransport regulation

Regulation of IDATME

•Ingestion regulates digestion •Digestion regulates absorption•Absorption regulates transport•Transport regulates metabolism (WWFQ)•Metabolism regulates excretion

Common digestive problemschoking- 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 mealsand a gradual increase in fibre

Common digestive problemsconstipation-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 ingut and rest goes to bacteria that make gas

-solution-change diet

Common digestive problems

heartburn and acid indigestioncause-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

disorders causing excessive gastric acid secretion

treat via- antibiotics

- withdrawl of offending foods

-withdrawal of caffeine or

alcohol on acase by case basis

Next lecture

Carbohydrates-structure and classification

-IDATME of carbohydrate