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LECTURE PRESENTATIONSFor CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
© 2011 Pearson Education, Inc.
Lectures byErin Barley
Kathleen Fitzpatrick
Animal Nutrition
Chapter 41
Concept 41.1: An animal’s diet must supply chemical energy, organic molecules, and essential nutrients
• An animal’s diet provides:1. Chemical energy, which is converted into ATP
to power cellular processes
2. Organic building blocks, such as organic carbon and organic nitrogen, to synthesize a variety of organic molecules
3. Essential nutrients, which are required by cells and must be obtained from dietary sources
© 2011 Pearson Education, Inc.
Essential Nutrients
• There are four classes of essential nutrients:1. Essential amino acids
2. Essential fatty acids
3. Vitamins - organic
4. Minerals - inorganic
© 2011 Pearson Education, Inc.
• 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
© 2011 Pearson Education, Inc.
What is the problem with a vegan diet?
Assessing Nutritional Needs
What is the difference between malnourishment and undernourishment?
•Insights into human nutrition have come from epidemiology, the study of human health and disease in populations•Example: neural tube defects were found to be the result of a deficiency in folic acid in pregnant mothers
© 2011 Pearson Education, Inc.
Can diet influence the frequency of birth defects?
RESULTS
Group
Number ofinfants/fetuses
studied
Vitamin supplements(experimental group)
No vitamin supplements(control group)
141
204
1 (0.7%)
12 (5.9%)
Infants/fetuseswith a neuraltube defect
Mechanicaldigestion Chemical
digestion(enzymatichydrolysis)
Nutrient moleculesenter body cells
Undigestedmaterial
EliminationAbsorptionDigestionIngestion1 2 3 4
•Concept 41.2: The main stages of food processing are ingestion, digestion, absorption, and elimination
Bulk Feeders
Suspension Feeders and Filter Feeders
Fluid FeedersBaleen
FecesCaterpillar
SubstrateFeeders
Figure 41.6
Figure 41.7
Mouth
Tentacles
Food
Epidermis Gastrodermis
Food particlesengulfed anddigested
Foodparticles brokendown
Digestiveenzymes released1
2
3
Crop
Gizzard
Intestine
Anus
Esophagus
Pharynx
Mouth
(a) Earthworm
Midgut EsophagusCrop
Mouth
StomachGizzard
Intestine
Anus
AnusRectumEsophagus
Crop
HindgutForegut
Mouth Gastric cecae
(b) Grasshopper (c) Bird
Variation in alimentary canals.
Consistent layout of most mammals
Liver
Salivaryglands
Gall-bladder
Esophagus
Pharynx
Oral cavity
Sphincter
Mouth
Stomach
Esophagus
Tongue
Pancreas
SmallintestineLargeintestine
RectumAnus
SphincterStomach
Duodenum ofsmall intestine
Pancreas
Schematic diagramAnusRectum
Largeintestine
SmallintestineLiver
Salivaryglands
Gall-bladder
Tongue
Pharynx
Glottis
Larynx
Bolus offood
Epiglottisup
EsophagealsphinctercontractedEsophagus
To lungs To stomach
Trachea
peristalsis
Tongue
Pharynx
Glottis
Larynx
Bolus offood
Epiglottisup
EsophagealsphinctercontractedEsophagus
To lungs To stomach
Trachea
peristalsis
Tongue
Pharynx
Glottis
Larynx
Bolus offood
Epiglottisup
EsophagealsphinctercontractedEsophagus
To lungs To stomach Relaxedmuscles
Contractedmuscles
Sphincterrelaxed
Stomach
Trachea
peristalsis
Digestion in the Stomach
• The stomach stores food and secretes gastric juice, which converts a bolus to acid chyme
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
Gastric gland
Gastric pits oninterior surface
of stomach
Sphincter
Smallintestine
Epithelium
Mucous cell
Chief cell
Parietal cell
Chiefcell
Pepsinogen
Parietalcell
Pepsin
Folds ofepithelialtissue
Sphincter
Esophagus
Stomach
3
2
1
10
m
HCl
H
Cl
Figure 41.11
Chemical digestion in the human digestive system.
Carbohydrate digestion
Polysaccharides
Salivary amylase
Smallerpolysaccharides
Maltose
Oral cavity,pharynx,esophagus
Figure 41.12-2
Protein digestion
Small polypeptides
Proteins
Pepsin
Carbohydrate digestion
Polysaccharides
Salivary amylase
Smallerpolysaccharides
Maltose
Stomach
Oral cavity,pharynx,esophagus
Figure 41.12-3
Fat digestionNucleic acid digestion
Protein digestion
Fat (triglycerides)DNA, RNA
Nucleotides
Pancreaticnucleases
Pancreatic lipase
Glycerol, fatty acids,monoglyceridesSmall peptides
Pancreatic carboxypeptidase
Smallerpolypeptides
Pancreatic trypsin andchymotrypsin
Small polypeptides
Proteins
Pepsin
Carbohydrate digestion
Polysaccharides
Salivary amylase
Smallerpolysaccharides
Maltose
Pancreatic amylases
Disaccharides
Smallintestine(enzymesfrompancreas)
Stomach
Oral cavity,pharynx,esophagus
Fat digestionNucleic acid digestion
Protein digestion
Fat (triglycerides)DNA, RNA
Nucleotides
Pancreaticnucleases
Pancreatic lipase
Glycerol, fatty acids,monoglycerides
Nucleotidases
Nucleosides
Nucleosidasesandphosphatases
Nitrogenous bases,sugars, phosphatesAmino acids
Dipeptidases, carboxy-peptidase, andaminopeptidase
Small peptides
Pancreatic carboxypeptidase
Smallerpolypeptides
Pancreatic trypsin andchymotrypsin
Small polypeptides
Proteins
Pepsin
Carbohydrate digestion
Polysaccharides Disaccharides
Salivary amylase
Smallerpolysaccharides
Maltose
Pancreatic amylases
Disaccharides
Disaccharidases
Monosaccharides
Smallintestine(enzymesfromepithelium)
Smallintestine(enzymesfrompancreas)
Stomach
Oral cavity,pharynx,esophagus
Figure 41.12-4
• 15 – 32 feet in humans
• 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– Most of nutrient digestion here– Jejunum and ilium mostly extract water– Some nutrients diffuse through membranes, most are pumped against gradient
© 2011 Pearson Education, Inc.
Most of absorption happens in the small intestine
Pancreatic Secretions
• The pancreas produces proteases trypsin and chymotrypsin that are activated in the lumen of the duodenum
• Its solution is alkaline…Why?
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
Figure 41.13 Nutrient absorption in the small intestine.
Vein carryingblood to liver
Muscle layers
Bloodcapillaries
Villi
Intestinal wall
Epithelialcells
Largecircularfolds
Key
Nutrientabsorption
VilliMicrovilli (brushborder) at apical(lumenal) surface
Epithelialcells
Lumen
Basalsurface
Lacteal
Lymphvessel
•membrane transport review bioflix
• 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
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Figure 41.15
Ascendingportionof colon
Smallintestine
AppendixCecum
•90% of water consumed is reabsorbed.•What happens if too much is absorbed? Too little?
•The colon’s primary purpose is to absorb water from chyme.
• There are approximately 500 species of bacteria comprising the gut flora (part of the “human microbiome”) that aid in digestion – 100 trillion cells compared to 10 trillion actual body
cells
Why don’t we eat feces?
© 2011 Pearson Education, Inc.
Symbiotic bacteria and digestion
• There are approximately 500 species of bacteria comprising the gut flora (part of the “human microbiome”) that aid in digestion – 100 trillion cells compared to 10 trillion actual body cells
Why don’t we eat feces? 30% of dry weight of feces is bacteria.
• Dogs and gorillas practice coprophagia for different reasons. Why? proof
© 2011 Pearson Education, Inc.
Symbiotic bacteria and digestion
• Feces are stored in the rectum until they can be eliminated through the anus
• Two sphincters between the rectum and anus control bowel movements, the top being involuntary, the bottom (anus) being voluntary
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
Concept 41.5: Feedback circuits regulate digestion, energy storage, and appetite
• 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
© 2011 Pearson Education, Inc.
Hormonal control of digestion.
Liver
Gallbladder
Food
Stomach
Duodenumof small intestine
Gastricjuices
Pancreas
Bile
Chyme
1 2 3
Gastrin
CCK
Key
StimulationInhibition
HCO3, enzymes
CCKSecretin
Secretinand CCK
Gastricjuices
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 adipose tissue, the most
space-efficient storage tissue
© 2011 Pearson Education, Inc.
Glucose Homeostasis
• Oxidation of glucose generates ATP to fuel cellular processes
• 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
© 2011 Pearson Education, Inc.
Blood sugar regulation bioflix
Figure 41.20
Transport ofglucose intobody cellsand storageof glucoseas glycogen
Breakdownof glycogenand releaseof glucoseinto blood
Homeostasis:70–110 mg glucose/100 mL blood
Stimulus:Blood glucose
level dropsbelow set point.
Pancreassecretesglucagon.
Stimulus:Blood glucose
level risesafter eating.
Pancreassecretesinsulin.
EXPERIMENT
Obese mouse with mutantob gene (left) next to wild-typemouse
RESULTSGenotype pairing
(red type indicatesmutant genes)
Average changein body mass (g)
of subject
8.3
38.7
8.2
14.9*
Paired with
obob , dbdb obob , dbdb
ob ob, dbdb ob ob, dbdb
ob ob, dbdb obob, dbdb
ob ob, dbdb obob, db db
Subject
*Due to pronounced weight loss and weakening, subjects in this pairing werereweighed after less than eight weeks.
Figure 41.22
FRQ du jourHomeostatic maintenance of optimal blood glucose levels has been intensively studied in vertebrate organisms.
(a)Pancreatic hormones regulate blood glucose levels. Identify TWO pancreatic hormones and describe the effect of each hormone on blood glucose levels.
(b)For ONE of the hormones you identified in (a), identify ONE target cell and discuss the mechanism by which the hormone can alter activity in that target cell. Include in your discussion a description of reception, cellular transduction, and response.
(c)Compare the cell-signaling mechanisms of steroid hormones and protein hormones.
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