41 lecture presentation

CAMPBELL
BIOLOGY
Reece • Urry • Cain • Wasserman • Minorsky • Jackson
© 2014 Pearson Education, Inc.
TENTH
EDITION
41
Animal Nutrition
Lecture Presentation by
Nicole Tunbridge and
Kathleen Fitzpatrick

The Need to Feed
 Food is taken in, taken apart, and taken up in the
process of animal nutrition
 In general, animals fall into three categories
 Herbivores eat mainly plants and algae
 Carnivores eat other animals
 Omnivores regularly consume animals as well as
plants or algae
 Most animals are also opportunistic feeders

Figure 41.1

Concept 41.1: An animal’s diet must supply
chemical energy, organic molecules, and
essential nutrients
 An animal’s diet must provide
 Chemical energy for cellular processes
 Organic building blocks for macromolecules
 Essential nutrients

Essential Nutrients
 Materials that an animal cannot assemble from
simpler organic molecules are called essential
nutrients
 These must be obtained from an animal’s diet
 There are four classes
 Essential amino acids
 Essential fatty acids
 Vitamins
 Minerals

Figure 41.2
Vitamin B3
Iron
Linoleic acid
NADH
Fatty acid desaturase
ESSENTIAL
AMINO ACIDS
Phospholipids
-Linoleic acid
Prostaglandins
Gly
Ile
Leu
Phe
Phe
Tyr
Glu

Essential Amino Acids
 Animals require 20 amino acids and can
synthesize about half from molecules in their diet
 The remaining amino acids, the essential amino
acids, must be obtained from food in
preassembled form
 Meat, eggs, and cheese provide all the essential
amino acids and are thus “complete” proteins

 Most plant proteins are incomplete in amino acid
composition
 Individuals who eat only plant proteins need to eat
specific plant combinations to get all the essential
amino acids
 Some animals have adaptations that help them
through periods when their bodies demand
extraordinary amounts of protein

Essential Fatty Acids
 Animals can synthesize most of the fatty acids
they need
 The essential fatty acids must be obtained from
the diet and include certain unsaturated fatty acids
(i.e., fatty acids with one or more double bonds)
 Deficiencies in fatty acids are rare

Vitamins
 Vitamins are organic molecules required in the
diet in very small amounts
 Thirteen vitamins are essential for humans
 Vitamins are grouped into two categories: fat-
soluble and water-soluble

Table 41.1

Minerals
 Minerals are simple inorganic nutrients, usually
required in small amounts
 Ingesting large amounts of some minerals can
upset homeostatic balance

Table 41.2

Dietary Deficiencies
 Malnutrition is a failure to obtain adequate nutrition
 Malnutrition can have negative impacts on health
and survival

Deficiencies in Essential Nutrients
 Deficiencies in essential nutrients can cause
deformities, disease, and death
 Cattle, deer, and other herbivores can prevent
phosphorus deficiency by consuming concentrated
sources of salt or other minerals
 “Golden Rice” is an engineered strain of rice with
beta-carotene, which is converted to vitamin A in
the body

Figure 41.3

Undernutrition
 Undernutrition results when a diet does not
provide enough chemical energy
 An undernourished individual will
 Use up stored fat and carbohydrates
 Break down its own proteins
 Lose muscle mass
 Suffer protein deficiency of the brain
 Die or suffer irreversible damage

Assessing Nutritional Needs
 Many insights into human nutrition have come
from epidemiology, the study of human health and
disease in populations
 Neural tube defects were found to be the result of
a deficiency in folic acid in pregnant mothers

Figure 41.4
Vitamin supplements
(experimental group)
No vitamin supple-
ments (control group)
141
204
1
12
Group
Number of
Infants/Fetuses
Studied
Infants/Fetuses
with a Neural
Tube Defect
Results

Concept 41.2: The main stages of food
processing are ingestion, digestion, absorption,
and elimination
 Ingestion is the act of eating or feeding
 Strategies for extracting resources from food differ
widely among animal species

Figure 41.5
Mechanical
digestion
Chemical
digestion
(enzymatic
hydrolysis)
Nutrient
molecules
enter
body cells
Undigested
material
INGESTION
DIGESTION
ABSORPTION
ELIMINATION
1
2
3
4

Suspension Feeders
 Many aquatic animals are suspension feeders,
which sift small food particles from the water

Figure 41.6a
Filter feeding
Baleen

Video: Shark Eating a Seal

Video: Lobster Mouth Parts

Substrate Feeders
 Substrate feeders are animals that live in or on
their food source

Figure 41.6b
Substrate
feeding
Caterpillar
Feces

Fluid Feeders
 Fluid feeders suck nutrient-rich fluid from a living
host

Figure 41.6c
Fluid feeding

Bulk Feeders
 Bulk feeders eat relatively large pieces of food

Figure 41.6d
Bulk feeding

 Digestion is the process of breaking food down
into molecules small enough to absorb
 Mechanical digestion, such as chewing, increases
the surface area of food
 Chemical digestion splits food into small
molecules that can pass through membranes;
these are used to build larger molecules
 In chemical digestion, the process of enzymatic
hydrolysis splits bonds in molecules with the
addition of water

 Absorption is uptake of nutrients by body cells
 Elimination is the passage of undigested material
out of the digestive system

Digestive Compartments
 Most animals process food in specialized
compartments
 These compartments reduce the risk of an animal
digesting its own cells and tissues

Intracellular Digestion
 In intracellular digestion, food particles are
engulfed by phagocytosis
 Food vacuoles, containing food, fuse with
lysosomes containing hydrolytic enzymes
 A few animals, such as sponges, digest their food
entirely by this mechanism

Extracellular Digestion
 Extracellular digestion is the breakdown of food
particles outside of cells
 It occurs in compartments that are continuous with
the outside of the animal’s body
 Animals with simple body plans have a
gastrovascular cavity that functions in both
digestion and distribution of nutrients

Figure 41.7
Mouth
Tentacles
Food
Epidermis Gastrodermis
Digestive enzymes
are released from a
gland cell.
Enzymes break
food down into small
particles.
Food particles are
engulfed and digested
in food vacuoles.
1
2
3

Video: Hydra Eating Daphnia (Time Lapse)

 More complex animals have a digestive tube with
two openings, a mouth and an anus
 This digestive tube is called a complete digestive
tract or an alimentary canal
 It can have specialized regions that carry out
digestion and absorption in a stepwise fashion

Figure 41.8
Esophagus
Esophagus
Esophagus
Crop
Crop
Crop
Gizzard
Gizzard
Intestine
Intestine
Anus
Anus
Anus
Mouth
Mouth
Mouth
Stomach
Foregut Midgut Hindgut
Rectum
Gastric cecae
(a) Earthworm
(b) Grasshopper
(c) Bird
Pharynx

Concept 41.3: Organs specialized for sequential
stages of food processing form the mammalian
digestive system
 The mammalian digestive system consists of an
alimentary canal and accessory glands that
secrete digestive juices through ducts
 Mammalian accessory glands are the salivary
glands, the pancreas, the liver, and the gallbladder

 Food is pushed along by peristalsis, rhythmic
contractions of muscles in the wall of the canal
 Valves called sphincters regulate the movement
of material between compartments

Figure 41.9
Tongue
Salivary
glands
Oral cavity
Pharynx
Esophagus
Sphincter
Liver
Stomach
Gall-
bladder
Small
intestine
Pancreas
Pancreas
Small
intestine
Large
intestine
Large
intestine
Gall-
bladder
Stomach
LiverSphincter
Esophagus
Rectum
Anus
Mouth
Anus
Rectum
Salivary
glands
Duodenum of
small intestine

The Oral Cavity, Pharynx, and Esophagus
 The first stage of digestion is mechanical and
takes place in the oral cavity
 Salivary glands deliver saliva to lubricate food
 Teeth chew food into smaller particles that are
exposed to salivary amylase, initiating breakdown
of glucose polymers
 Saliva also contains mucus, a viscous mixture of
water, salts, cells, and glycoproteins

 The tongue shapes food into a bolus and provides
help with swallowing
 The throat, or pharynx, is the junction that opens
to both the esophagus and the trachea
 The esophagus connects to the stomach
 The trachea (windpipe) leads to the lungs

 The esophagus conducts food from the pharynx
down to the stomach by peristalsis
 Swallowing causes the epiglottis to block entry to
the trachea, and the bolus is guided by the larynx,
the upper part of the respiratory tract
 Coughing occurs when the swallowing reflex fails
and food or liquids reach the windpipe

Figure 41.10
Tongue
Pharynx
Glottis
Larynx
Trachea
Bolus of
food
Epiglottis
up
Esophageal
sphincter
contracted
Esophagus
To
lungs
To
stomach
(a) Trachea open
Epiglottis
down
Glottis up
and closed
Esophageal
sphincter
relaxed
(b) Esophagus open

Digestion in the Stomach
 The stomach stores food and begins digestion of
proteins
 The stomach secretes gastric juice, which
converts a meal to chyme

Chemical Digestion in the Stomach
 Gastric juice has a low pH of about 2, which kills
bacteria and denatures proteins
 Gastric juice is made up of hydrochloric acid (HCl)
and pepsin
 Pepsin is a protease, or protein-digesting
enzyme, that cleaves proteins into smaller
peptides

 Parietal cells secrete hydrogen and chloride ions
separately into the lumen (cavity) of the stomach
 Chief cells secrete inactive pepsinogen, which is
activated to pepsin when mixed with hydrochloric
acid in the stomach
 Mucus protects the stomach lining from gastric
juice

Figure 41.11
Stomach
Gastric pit
on the interior
surface of
stomach
Gastric gland
Mucous cell
Chief cell
Parietal cell
Epithelium
Pepsinogen
Chief
cell
Pepsin
(active
enzyme)
Parietal
cell
HCl
Cl−
H+
1
2
3

Figure 41.11a
Gastric pit
on the interior
surface of
stomach
Gastric gland
Mucous cell
Chief cell
Parietal cell
Epithelium

Figure 41.11b-1
Pepsinogen
Chief
cell
Production of gastric
juice
Parietal
cell
HCl
Cl−
H+
1
1
Pepsinogen and
HCl secreted into
lumen

Figure 41.11b-2
Pepsinogen
Chief
cell
juice
Parietal
cell
HCl
Cl−
H+
1
1
Pepsinogen and
HCl secreted into
lumen
HCl converts
pepsinogen to
pepsin.
2
2
Pepsin
(active
enzyme)

Figure 41.11b-3
Pepsinogen
Chief
cell
juice
Parietal
cell
HCl
Cl−
H+
1
1
Pepsinogen and
HCl secreted into
lumen
HCl converts
pepsinogen to
pepsin.
2
2
Pepsin
(active
enzyme)
Pepsin activates
more pepsinogen,
starting a chain
reaction.
3
3

 Gastric ulcers, lesions in the lining, are caused
mainly by the bacterium Helicobacter pylori

Stomach Dynamics
 Coordinated contraction and relaxation of stomach
muscle churn the stomach’s contents
 Sphincters prevent chyme from entering the
esophagus and regulate its entry into the small
intestine

Digestion in the Small Intestine
 The small intestine is the longest compartment of
the alimentary canal
 Most enzymatic hydrolysis of macromolecules
from food occurs here

Figure 41.12
ORAL
CAVITY,
PHARYNX,
ESOPHAGUS
STOMACH
SMALL
INTESTINE
(enzymes
from
pancreas)
SMALL
INTESTINE
(enzymes
from
intestinal
epithelium)
CARBOHYDRATE DIGESTION
PROTEIN DIGESTION
NUCLEIC ACID DIGESTION FAT DIGESTION
Polysaccharides
(starch, glycogen)
Disaccharides
(sucrose, lactose)
MaltoseSmaller
polysaccharides
Salivary amylase
Pancreatic amylases
Disaccharides
Disaccharidases
Monosaccharides
Proteins
Pepsin
Small polypeptides
Pancreatic trypsin and
chymotrypsin
Smaller
polypeptides
Pancreatic carboxypeptidase
Small peptides
Dipeptidases, carboxy-
peptidase, and
aminopeptidase
Amino acids
DNA, RNA
Pancreatic
nucleases
Nucleotides
Nucleotidases
Nucleosides
Nucleosidases
and
phosphatases
Nitrogenous bases,
sugars, phosphates
Fat (triglycerides)
Pancreatic lipase
Glycerol, fatty acids,
monoglycerides

Figure 41.12a
ORAL CAVITY, PHARYNX, ESOPHAGUS
CARBOHYDRATE
DIGESTION
Polysaccha-
rides
(starch,
glycogen)
Disaccha-
rides
(sucrose,
lactose)
MaltoseSmaller
polysaccharides
Salivary amylase

Figure 41.12b
STOMACH
CARBOHYDRATE
DIGESTION
ProteinsDisaccha-
rides
(sucrose,
lactose)
MaltoseSmaller
polysaccha-
rides Pepsin
Small
polypeptides
PROTEIN
DIGESTION

Figure 41.12c
SMALL INTESTINE (enzymes from pancreas)
CARBOHYDRATE
DIGESTION
Smaller
polypeptides
Disaccha-
rides
(sucrose,
lactose,
maltose)
Disaccharides
Smaller
polysaccha-
rides
Pancreatic
amylases
Small
polypeptides
PROTEIN
DIGESTION
NUCLEIC ACID
DIGESTION
FAT
DIGESTION
Pancreatic
trypsin and
chymotrypsin
Pancreatic
carboxy-
peptidase
Small
peptides
Amino
acids
DNA, RNA
Nucleotides
Fat
(triglycerides)
Pancreatic
lipase
Glycerol,
fatty acids,
monoglycerides
Pancreatic
nucleases

Figure 41.12d
SMALL INTESTINE (enzymes from intestinal epithelium)
CARBOHYDRATE
DIGESTION
Disaccha-
rides
(sucrose,
lactose,
maltose)
Monosaccharides
Disaccharidases
PROTEIN
DIGESTION
NUCLEIC ACID
DIGESTION
Nucleosidases
and
phosphatases
Dipeptidases,
carboxypeptidase,
and aminopeptidase
Small
peptides
Amino acids
Nucleotides
Nucleotidases
Amino acids
Nitrogenous bases,
sugars, phosphates

 The first portion of the small intestine is the
duodenum, where chyme from the stomach mixes
with digestive juices from the pancreas, liver,
gallbladder, and the small intestine itself

Pancreatic Secretions
 The pancreas produces proteases trypsin and
chymotrypsin that are activated in the lumen of the
duodenum
 Its solution is alkaline and neutralizes the acidic
chyme

Bile Production by the Liver
 In the small intestine, bile aids in digestion and
absorption of fats
 Bile is made in the liver and stored in the
gallbladder
 Bile also destroys nonfunctional red blood cells

Secretions of the Small Intestine
 The epithelial lining of the duodenum produces
several digestive enzymes
 Enzymatic digestion is completed as peristalsis
moves the chyme and digestive juices along the
small intestine
 Most digestion occurs in the duodenum; the
jejunum and ileum function mainly in absorption of
nutrients

Absorption in the Small Intestine
 The small intestine has a huge surface area, due
to villi and microvilli that are exposed to the
intestinal lumen
 The enormous microvillar surface creates a brush
border that greatly increases the rate of nutrient
absorption
 Transport across the epithelial cells can be
passive or active depending on the nutrient

Figure 41.13
Vein carrying
blood to liver
Blood
capillaries
Epithelial
cells
Large
circular
folds
Muscle layers
Villi
Intestinal
wall
Nutrient
absorption
Lacteal
Lymph
vessel
Villi
(toward
capillary)
LumenEpithelial
cells
Microvilli
(brush border)
at apical (lumenal)
surface
Basal
surface

BioFlix: Membrane Transport

 The hepatic portal vein carries nutrient-rich blood
from the capillaries of the villi to the liver, then to
the heart
 The liver regulates nutrient distribution,
interconverts many organic molecules, and
detoxifies many organic molecules

 Epithelial cells absorb fatty acids and
monoglycerides and recombine them into
triglycerides
 These fats are coated with phospholipids,
cholesterol, and proteins to form water-soluble
chylomicrons
 Chylomicrons are transported into a lacteal, a
lymphatic vessel in each villus
 Lymphatic vessels deliver chylomicron-containing
lymph to large veins that return blood to the heart

Figure 41.14
LUMEN
OF SMALL
INTESTINE
Epithelial
cell
Triglycerides
Fatty
acids Monoglycerides
Triglycerides
Phospholipids,
cholesterol,
and
proteins
Chylomicron
Lacteal
Triglycerides
are broken
down to fatty
acids and
monoglycerides
by lipase.
Monoglycerides
and fatty acids
diffuse into
epithelial cells
and are reformed
into triglycerides.
Triglycerides are
incorporated into
chylomicrons.
Chylomicrons
enter lacteals
and are carried
away by lymph.
1
2
3
4

Figure 41.14a
LUMEN
OF SMALL
INTESTINE
Epithelial
cell
Triglycerides
Fatty
acids Monoglycerides
Triglycerides
Triglycerides
are broken
down to fatty
acids and
monoglycerides
by lipase.
Monoglycerides
and fatty acids
diffuse into
epithelial cells
and are reformed
into triglycerides.
1
2

Figure 41.14b
Triglycerides
Phospholipids,
cholesterol,
and
proteins
Chylomicron
Lacteal
Triglycerides are
incorporated into
chylomicrons.
Chylomicrons
enter lacteals
and are carried
away by lymph.
3
4

Processing in the Large Intestine
 The colon of the large intestine is connected to
the small intestine
 The cecum aids in the fermentation of plant
material and connects where the small and large
intestines meet
 The human cecum has an extension called the
appendix, which plays a minor role in immunity

Figure 41.15
Ascending
portion
of colon
Small
intestine
Appendix
Cecum

 The colon completes the reabsorption of water
that began in the small intestine
 Feces, including undigested material and bacteria,
become more solid as they move through the
colon

 Feces are stored in the rectum until they can be
eliminated through the anus
 Two sphincters between the rectum and anus
control bowel movements

Concept 41.4: Evolutionary adaptations of
vertebrate digestive systems correlate with diet
 Digestive systems of vertebrates are variations on
a common plan
 However, there are intriguing adaptations, often
related to diet

Dental Adaptations
 Dentition, an animal’s assortment of teeth, is one
example of structural variation reflecting diet
 The success of mammals is due in part to their
dentition, which is specialized for different diets
 Nonmammalian vertebrates have less specialized
teeth, though exceptions exist
 For example, the teeth of poisonous snakes are
modified as fangs for injecting venom

Figure 41.16
Carnivore Herbivore
Omnivore
Key Incisors Canines Premolars Molars

Stomach and Intestinal Adaptations
 Many carnivores have large, expandable
stomachs
 Herbivores and omnivores generally have longer
alimentary canals than carnivores, reflecting the
longer time needed to digest vegetation

Figure 41.17
Small
intestine
Carnivore
Stomach
Cecum
Colon
(large
intestine)
Small intestine
Herbivore

Figure 41.17a

Figure 41.17b

Mutualistic Adaptations
 The coexistence of humans and many bacteria
involves mutualistic symbiosis
 Some intestinal bacteria produce vitamins;
intestinal bacteria also regulate the development
of the intestinal epithelium and the function of the
innate immune system
 Using a DNA sequencing approach based on the
polymerase chain reaction, scientists have found
more than 400 bacterial species in the human
digestive tract

Figure 41.18
Uninfected
individuals
Individuals
with H. pylori
infection
H. pylori
Percentofsampledstomachbacteria
Phylum
100
80
60
40
20
0

Figure 41.18a
H. pylori

Mutualistic Adaptations in Herbivores
 Many herbivores have fermentation chambers,
where mutualistic microorganisms digest cellulose
 The most elaborate adaptations for an herbivorous
diet have evolved in the animals called ruminants

Figure 41.19
Reticulum
Esophagus
Rumen
Omasum
Abomasum
Intestine
4
3
2
1

Concept 41.5: Feedback circuits regulate
digestion, energy storage, and appetite
 The processes that enable an animal to obtain
nutrients are matched to the organism’s
circumstances and need for energy

Regulation of Digestion
 Each step in the digestive system is activated as
needed
 The enteric division of the nervous system helps to
regulate the digestive process
 The endocrine system also regulates digestion
through the release and transport of hormones

Figure 41.20
Gallbladder
1 2
3
Liver Food
Stomach
Gastric
juices
Gastrin
Pancreas
Duodenum of
small intestine
Bile
CCK
Chyme
HCO3
, enzymes
Secretin
CCK
Secretin
and CCK
Gastric
juices
Stimulation
Inhibition

Figure 41.20a
Gallbladder
Liver Food
Stomach
Gastric
juices
Gastrin
Pancreas
Duodenum of
small intestine
Stimulation
Inhibition
1

Figure 41.20b
Stimulation
Inhibition
2
Bile
CCK
Chyme
HCO3
, enzymes
Secretin CCK

Figure 41.20c
Stimulation
Inhibition
3
Secretin
and CCK
Gastric
juices

Regulation of Energy Storage
 The body stores energy-rich molecules that are
not needed right away for metabolism
 In humans, energy is stored first in the liver and
muscle cells in the polymer glycogen
 Excess energy is stored in fat in adipose cells
 When fewer calories are taken in than expended,
the human body expends liver glycogen first, then
muscle glycogen and fat

Glucose Homeostasis
 Glucose is a major fuel for cellular respiration and
a key source of carbon skeletons for biosynthesis
 The hormones insulin and glucagon regulate the
breakdown of glycogen into glucose
 The liver is the site for glucose homeostasis
 A carbohydrate-rich meal raises insulin levels,
which triggers the synthesis of glycogen
 Low blood sugar causes glucagon to stimulate the
breakdown of glycogen and release glucose

Figure 41.21
Secretion
of insulin
by beta
cells of the
pancreas
Transport of
glucose into
body cells
and storage
of glucose
as glycogen
Secretion of
glucagon by
alpha cells
of the
pancreas
Breakdown of
glycogen and
release of
glucose into blood
Blood glucose
level rises.
Blood glucose
level falls.
Insulin
Glucagon
Blood glucose
level rises
(such as after eating).
Blood glucose
level falls
(such as after fasting).
NORMAL BLOOD
GLUCOSE
(70–110 mg glucose/
100 mL)

BioFlix: Homeostasis: Regulating Blood Sugar

 Insulin acts on nearly all body cells to stimulate
glucose uptake from blood
 Brain cells are an exception; they can take up
glucose whether or not insulin is present
 Glucagon and insulin are both produced in the
islets of the pancreas
 Alpha cells make glucagon and beta cells make
insulin

Diabetes Mellitus
 The disease diabetes mellitus is caused by a
deficiency of insulin or a decreased response to
insulin in target tissues
 Cells are unable to take up enough glucose to
meet metabolic needs
 The level of glucose in the blood may exceed the
capacity of kidneys to reabsorb it
 Sugar in the urine is one test for diabetes

 Type 1 diabetes is an autoimmune disorder in which
the immune system destroys the beta cells of the
pancreas
 It usually appears during childhood
 Type 2 diabetes is characterized by a failure of target
cells to respond normally to insulin
 Excess body weight and lack of exercise significantly
increase the risk of type 2 diabetes
 It generally appears after age 40, but may develop
earlier in younger people who are sedentary

Regulation of Appetite and Consumption
 Overnourishment causes obesity, which results
from excessive intake of food energy with the
excess stored as fat
 Obesity contributes to diabetes (type 2), cancer of
the colon and breasts, heart attacks, and strokes
 Researchers have discovered several of the
mechanisms that help regulate body weight

 Hormones regulate long-term and short-term
appetite by affecting a “satiety center” in the brain
 Ghrelin, a hormone secreted by the stomach wall,
triggers feelings of hunger before meals
 Insulin and PYY, a hormone secreted by the small
intestine after meals, both suppress appetite
 Leptin, produced by adipose (fat) tissue, also
suppresses appetite and plays a role in regulating
body fat levels

Figure 41.22
Satiety
center
Ghrelin
Insulin
Leptin
PYY

Figure 41.UN02a
Genotype Pairing (red type
indicates mutant genes)
Average Change
in Body Mass
Subject (g)
Subject Paired with
(a)
(b)
(c)
(d)
ob
+
/ob
+
, db
+
/db
+
ob
+
/ob
+
, db
+
/db
+
ob/ob, db
+
/db
+
ob/ob, db
+
/db
+
ob
+
/ob
+
, db
+
/db
+
ob
+
/ob
+
, db/db
ob/ob, db
+
/db
+
ob/ob, db
+
/db
+
8.3
38.7
8.2
−14.9*
* Due to pronounced weight loss and weakening, subjects in this pairing were
remeasured after less than eight weeks.

Figure 41.UN02b

Figure 41.UN03
Stages of food
processing
Undigested
material
INGESTION
(eating)
DIGESTION
(enzymatic breakdown
of large molecules)
ABSORPTION
(uptake of nutrients
by cells)
ELIMINATION
(passage of undigested
materials out of the
body in feces)
1
2
3
4

Figure 41.UN04
Veins to heart
Lymphatic system
Hepatic portal vein
Liver
Mouth
Esophagus
Stomach
Lipids
Absorbed food
(except lipids)
Absorbed
water
Secretions
from
salivary
glands
Secretions
from
gastric
glands
Small intestine
Secretions from liver
Secretions from pancreas
Large
intestine
Anus
Rectum

Figure 41.UN05

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41 lecture presentation