why do we crave pizza so? how does a pizza help you make brain cells?

Why do we crave pizza so?

Why do we crave pizza so?

How does a pizza help you make brain cells?

Or a lean fish help a bear make fat?

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


Video: Lobster Mouth Parts


Video: Shark Eating a Seal

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


Essential Nutrients

• There are four classes of essential nutrients:1. Essential amino acids

2. Essential fatty acids

3. Vitamins - organic

4. Minerals - inorganic



What is the problem with a vegan diet?

• 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


What is the problem with a vegan diet?

Table 41.1

Table 41.2

Figure 41.3

Why is this fella licking the ground?

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


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


Video: Hydra Eating Daphnia

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 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


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


Why doesn’t the stomach digest itself?

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


Polysaccharides

Salivary amylase


Maltose

Stomach


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


Polysaccharides

Salivary amylase


Maltose

Pancreatic amylases

Disaccharides

Smallintestine(enzymesfrompancreas)

Stomach


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


Polysaccharides Disaccharides

Salivary amylase


Maltose

Pancreatic amylases

Disaccharides

Disaccharidases

Monosaccharides

Smallintestine(enzymesfromepithelium)

Smallintestine(enzymesfrompancreas)

Stomach


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


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?


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


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

http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?9apmembrane

• 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


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?


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


Symbiotic bacteria and digestion

https://www.youtube.com/watch?v=oAQubtm-IPg

• 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


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

Smallintestine Stomach

Cecum

Carnivore

Colon(largeintestine)

Small intestine

Herbivore

Reticulum

Esophagus

OmasumAbomasum

Intestine

Rumen1 2

34

Figure 41.18

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


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


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


Blood sugar regulation bioflix

http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?9aphomeostasis

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.

Faulty appetite-regulating hormones can lead to obesity

Satiety center

Ghrelin

Insulin

Leptin

PYY

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

What is the point, evolutionarily, of binge eating?

Dentition and diet.

Carnivore

Herbivore Omnivore

MolarsPremolarsCaninesIncisorsKey

•See 10-1, and also 10-2

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.

why do we crave pizza so? how does a pizza help you make brain cells?

Documents

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organic carbon

organic nitrogen

classes of essential

pregnant motherscan

chemical energy

human nutrition

brain cells