Transcript 21 - El Camino College

POWERPOINT® LECTURE SLIDE PRESENTATION
by LYNN CIALDELLA, MA, MBA, The University of Texas at Austin
Additional Text by J Padilla exclusively for Physiolgy at ECC
UNIT 4
21
PART A
The Digestive System
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
DEE UNGLAUB SILVERTHORN
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
FOURTH EDITION
Basic Processes of the Digestive System
Ingestion
Mechanical
Digestion
Chemical
Digestion
Absorption
Defication
Peristalsis
(motility)
Secretion
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-1
Digestion and Absorption
A villus and a crypt in the small intestine- stem cells in crypt
helps to replace the stomach lining. Crypts are used for
peptide absorption in newborns.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-13
Carbohydrate Digestion
American diets
are rich in
starch and
sucrose. Can
only absorb
monsacchirdes.
Cellulose is not
digestable
(fiber).
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-14
Carbohydrate Absorption in the Small Intestine
Glucose &
galactose
move via
transporter
and depend
on ion
movemnt.
Intestinal
cells use
glutamate as
an energy
source to
not consume
glucose.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-15
Enzymes for Protein Digestion
Endopeptidases
(proteases) break down
polypeptides to smaller
peptide fragments that
are then broken down by
exopeptidases in amino
acids. Endopeptidases
are usually released in an
inactive form
(proenzymes) that once
activated have a different
name: pepsin, trypsin,
and chymotrypsin.
*egg protein is the easiest
to digest and absorb
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-16
Peptide Absorption
Amino acids and
small peptides cross
the cell through
transporter proteins.
Larger peptides are
endocytosed.
Permeability of
peptides increases in
pregnant and
nursing women and
in newborns.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-17
Digestion and Absorption
Triglycerides digest into monoglycerides and free fatty
acids – lipases free the fatty acid chains, phospholipase
digest glycerol, and free cholesterol is not digested.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-18
Digestion and Absorption of Fats
Bile salts break down
large fat droplets are to
increase surface area
for digestion. This
forms an emulsion in
which colipase is
needed for lipase to
digest the fat and form
micelles. Fat diffuses in
and cholesterol is
moved by a transporter.
Chylomicrons form
inside cells and move
into lacteals. Some
smaller fatty acids
move into capillaries
Large fat droplets
from stomach
Bile salts
from liver
1
Emulsion
Bile salts
recycled
Lipase
2
and colipase
Micelles
Lumen of
small intestine
3a
3b
1 Bile salts from liver coat
fat droplets.
2 Pancreatic lipase and
colipase break down
fats into monoglycerides
and fatty acids stored
in micelles.
3a Monoglycerides and
fatty acids move out of
micelles and enter cells
by diffusion.
Smooth
ER
4 Triglycerides + cholesterol + protein
Cells of
small
intestine
Chylomicron
Golgi
apparatus
4 Absorbed fats combine
with cholesterol
and proteins in the
intestinal cells to form
chylomicrons.
5
Interstitial
fluid
Capillary
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
3b Cholesterol is
transported into cells
by a membrane
transporter.
Lacteal
Lymph
to
vena
cava
5 Chylomicrons are
released into the
lymphatic system.
Figure 21-19
Digestion and Absorption of Fats
Large fat droplets
from stomach
Bile salts
from liver
1
Emulsion
Lipase
2
and colipase
Micelles
1 Bile salts from liver coat
fat droplets.
2 Pancreatic lipase and
colipase break down
fats into monoglycerides
and fatty acids stored
in micelles.
Lumen of
small intestine
Cells of
small
intestine
Interstitial
fluid
Capillary
Lacteal
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-19, steps 1–2
Digestion and Absorption of Fats
Large fat droplets
from stomach
Bile salts
from liver
1
Emulsion
Lipase
2
and colipase
Micelles
Bile salts
recycled
Lumen of
small intestine
1 Bile salts from liver coat
fat droplets.
2 Pancreatic lipase and
colipase break down
fats into monoglycerides
and fatty acids stored
in micelles.
3a Monoglycerides and
fatty acids move out of
micelles and enter cells
by diffusion.
3a
Cells of
small
intestine
Interstitial
fluid
Capillary
Lacteal
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-19, steps 1–3a
Digestion and Absorption of Fats
Large fat droplets
from stomach
Bile salts
from liver
1
Emulsion
Lipase
2
and colipase
Micelles
Lumen of
small intestine
3a
Bile salts
recycled
3b
1 Bile salts from liver coat
fat droplets.
2 Pancreatic lipase and
colipase break down
fats into monoglycerides
and fatty acids stored
in micelles.
3a Monoglycerides and
fatty acids move out of
micelles and enter cells
by diffusion.
Smooth
ER
4 Triglycerides + cholesterol + protein
Cells of
small
intestine
Chylomicron
3b Cholesterol is
transported into cells
by a membrane
transporter.
4 Absorbed fats combine
with cholesterol
and proteins in the
intestinal cells to form
chylomicrons.
Interstitial
fluid
Capillary
Lacteal
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-19, steps 1–4
Digestion and Absorption of Fats
Large fat droplets
from stomach
Bile salts
from liver
1
Emulsion
Bile salts
recycled
Lipase
2
and colipase
Micelles
Lumen of
small intestine
3a
3b
1 Bile salts from liver coat
fat droplets.
2 Pancreatic lipase and
colipase break down
fats into monoglycerides
and fatty acids stored
in micelles.
3a Monoglycerides and
fatty acids move out of
micelles and enter cells
by diffusion.
Smooth
ER
4 Triglycerides + cholesterol + protein
Cells of
small
intestine
Chylomicron
Golgi
apparatus
4 Absorbed fats combine
with cholesterol
and proteins in the
intestinal cells to form
chylomicrons.
5
Interstitial
fluid
Capillary
3b Cholesterol is
transported into cells
by a membrane
transporter.
Lacteal
Lymph
to
vena
cava
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
5 Chylomicrons are
released into the
lymphatic system.
Figure 21-19, steps 1–5
Digestion and Absorption
The role of bile salts in emulsions and micelles
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-20
Digestion and Absorption
 Nucleic acids are digested into nitrogenous bases and
monosaccharides – all components are absorbed by transport mechanisms,
they are not considered a calorie source and make up a small % of the diet.
 Intestine absorbs vitamins and minerals – some vitamins must be
coupled with fats or proteins to be better absorbed.
 Fat-soluble absorbed with fats – excessive quantities and cause
toxicity. Incorrect fat ingestion can cause vitamin deficiency.
 Water-soluble by mediated transport – (C and most B vitamins), can
be excreted if there is excess
 Vitamin B12 when complexed to intrinsic factor and absorbed in
ileum – found in meats, sea food, and milk products.
 Mineral by active transport – Fe and Ca absorption is based on
need. Fe is absorbed as heme and Ca absorption is hormone
mediated or by passive movement.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Digestion and Absorption
NaCl reabsorption
in the small
intestine and
colon
Three transporters
are used to absorb
sodium so water
can move in too.
Ion movement
includes Cl-, H+,
K+, andHCO3-
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 21-21