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Final Exam
-3 hours 120 multiple choice (all lectures
after 17 February to the last lecture of the
course inclusive)
-4 short answer Questions (15 points
each) (all lectures for course)
Lecture 3
INGESTION/DIGESTION/
ABSORPTION/TRANSPORT/
METABOLISM/EXCRETION
11 JANUARY 2017
Overview of lecture 3
1) INGESTION
2) DIGESTION
3) ABSORPTION
4) TRANSPORT
5) METABOLISM
6) EXCRETION
7) REGULATION OF IDATME
INGESTION
• mouth- chewing and swallowing
• oral or nasal tube
• intravenous
DIGESTION
-process by which food is broken down into
absorbable units
-muscular action of digestion
-peristalsis
-stomach action-churning
-segmentation –small intestine
-sphincters-opening and closing valves
http://nutrition.jbpub.com/resources/animations.cf
m?id=1&debug=0
-secretions of digestion
Fig. 3-1, p. 71
DIGESTIVE GLANDS AND THEIR
SECRETIONS (ENZYMES)
-saliva
-gastric – water, HCl and pepsin-proteins
-pancreatic juice/intestinal enzymes
carbohydrases
lipases
proteases
file:///D:/Media/Animations/chapter3/Digestive_Sandwich/0308.html
Link only available in class
ABSORPTION
I) 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 simple and facilitated
diffusion or active transport with the
transport discussed below
II) ANATOMY-goblet cells/crypts/villi and
microvilli
Fig. 3-10, p. 79
TRANSPORT
defined
getting nutrients, via blood or
lymphatic systems, to where needed,
when needed, in the form needed
and in the correct quantities needed.
WWFQ
ANATOMY OF TRANSPORT
TWO ROUTES
-BLOOD AND LYMPH
ANATOMY OF TRANSPORT
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
ANATOMY OF TRANSPORT
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
file:///D:/Media/Animations/chapter3/Vascular_System/311.html
Link only available in class
METABOLISM
collection of all the reactions and their regulation
that go on in the body
constant anabolism and catabolism
METABOLISM
ANABOLISM – BUILDING UP
eg -amino acids to protein into muscle
-glucose into glycogen
-(carbohydrate storage)
-fatty acids into triglycerides (fat storage)
METABOLISM
CATABOLISM- TEARING DOWN
eg -muscle to protein to amino acids
-carbohydrate (glycogen into glucose)
-triglycerides into fatty acids
METABOLISM
ANABOLISM AND CATABOLISM
-assisted by vitamins, minerals
-water used in some catabolic reactions to
split molecules
-water formed by catabolism sometimes
-water formed in some anabolic reactions
Fig. 10-13, p. 347
Fig. 10-13, p. 347
Fig. 10-13, p. 347
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
-all hinges on homeostasis- define-maintenance of constant internal
conditions
-can be disrupted by
physical immaturity,
aging, illness, nutrition
REGULATION OF IDATME
INGESTION
FOOD INTO BODY- demanded by
hunger signals (really metabolic signals)
indicating dropping supplies of nutrients
INGESTION REGULATION LEADS
TO DIGESTION REGULATION
REGULATION OF IDATME
DIGESTION
-e.g. stomach pH homeostasis – pH 1.5
hormonal/neuronal regulation-important for digestion
REGULATION OF IDATME
Digestion regulation continued
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
Fig. 3-1, p. 71
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
-also neuronal regulation of peristalsis
-digestion regulation leads to absorption regulation
REGULATION OF IDATME
Absorption (transport across the small
intestine into blood or lymph)
-simple diffusion, facilitated diffusion,
active transport
REGULATION OF IDATME
ABSORPTION
-simple - move with concentration gradient
(regulation- high in small intestine
and low on other side) – e.g. water and
small lipids go across this way
-facilitated - move with concentration gradienthigh in small intestine and low on
other side-presence of carrier
(regulation -amount and activity of
carrier)- e.g. fructose and water
soluble vitamins go across this way.
REGULATION OF IDATME
ABSORPTION continued
-active - move against a concentration gradient
low in small intestine and high on
other side - a carrier and energy
required (regulation-amount and
activity of carrier and sufficient
energy) -e.g. calcium, amino
acids and glucose go across this
way.
REGULATION OF IDATME
ABSORPTION REGULATION LEADS TO
TRANSPORT REGULATION
REGULATION OF IDATME
Metabolism
-enzymes run the show
-enzymes in humans are proteins
(always) that allow reactions to go faster
than they would without the enzymes
-supply of and demand for metabolic
products control enzymatic rates
-high demand with low supply leads to faster
enzymatic rates
-low demand with high supply leads to
slower enzymatic rates
-metabolism regulation leads to excretion regulation
REGULATION OF IDATME
EXCRETION
-dumping of metabolic waste products
-primarily done by liver and kidneys
and intestine
ultimately regulates ingestion since retention of
metabolic waste products variously upsets
metabolism and may make one feel bloated or
nauseous with possible vomiting
Regulation of IDATME
•
•
•
•
•
•
ingestion regulates digestion
digestion regulates absorption
absorption regulates transport
transport regulates metabolism
metabolism regulates excretion
excretion regulates ingestion
So we have now gone full circle
Summary of lecture 3
1) INGESTION
2) DIGESTION
3) ABSORPTION
4) TRANSPORT
5) METABOLISM
6) EXCRETION
7) REGULATION OF IDATME
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