Animal NutritionAnimal NutritionChapter 41Chapter 41

NutritionNutrition Intake of food from external environmentIntake of food from external environment

A balanced diet provides fuel for cellular A balanced diet provides fuel for cellular work and the materials needed to work and the materials needed to construct organic moleculesconstruct organic molecules

Proper diet needed in order to maintain Proper diet needed in order to maintain homeostasis (balanced internal environ.)homeostasis (balanced internal environ.)

NutritionNutrition Nutrition satisfies three needs of animals: Nutrition satisfies three needs of animals:

– fuel (chemical energy) for metabolism fuel (chemical energy) for metabolism

–the organic raw materials (carbon the organic raw materials (carbon skeletons)skeletons)

–essential nutrientsessential nutrientssubstances animals can’t make substances animals can’t make themselves from themselves from anyany raw material raw material

–must obtain in food from must obtain in food from environmentenvironment

Energy (ATP)Energy (ATP)

Remember, cell resp. releases ATP Remember, cell resp. releases ATP by oxidizing food moleculesby oxidizing food molecules

–ATP powers basal or resting ATP powers basal or resting metabolism, as well as activity, metabolism, as well as activity, and, in endothermic animals, and, in endothermic animals, temperature regulationtemperature regulation

Biosynthesis and Energy StorageBiosynthesis and Energy Storage More calories than needed to produce ATP, More calories than needed to produce ATP,

excess can be used for biosynthesisexcess can be used for biosynthesis– growth in size, reproduction, or stored in growth in size, reproduction, or stored in

energy depotsenergy depots In humans, the liver and muscle cells store In humans, the liver and muscle cells store

energy as glycogen (polymer of glucose energy as glycogen (polymer of glucose units)units)

If glycogen stores are full and caloric intake If glycogen stores are full and caloric intake still exceeds caloric needs, excess stored as still exceeds caloric needs, excess stored as fatfat– Basis for recent low-carb diet trendBasis for recent low-carb diet trend

Regulation of Glucose Levels (ie: blood sugar)Regulation of Glucose Levels (ie: blood sugar)

High Glucose (High Blood Sugar)High Glucose (High Blood Sugar)

–Pancreas secretes Pancreas secretes insulininsulin promotes glucose storage as promotes glucose storage as glycogen in liver/muscles)glycogen in liver/muscles)

Low Glucose (Low Blood Sugar)Low Glucose (Low Blood Sugar)

–Pancreas secretes Pancreas secretes glucagonglucagonpromotes the breakdown of glycogen promotes the breakdown of glycogen and release of glucose into bloodand release of glucose into blood

Glucose Regulation (Pancreas)Glucose Regulation (Pancreas)

UndernourishmentUndernourishment When not receiving enough calories, the When not receiving enough calories, the

body breaks its energy stores down body breaks its energy stores down

–Body first depends on liver stores, then Body first depends on liver stores, then muscle and fat glycogenmuscle and fat glycogen

–Average adult has enough fat stores for Average adult has enough fat stores for weeks of starvationweeks of starvation

Severe malnutrition leads to loss of Severe malnutrition leads to loss of muscle mass and loss of brain proteinsmuscle mass and loss of brain proteins

–Brain damage, death, or permanent Brain damage, death, or permanent disability possibledisability possible

OvernourishmentOvernourishment

Leads to obesity (excess fat stores)Leads to obesity (excess fat stores)

–Leads to serious health issues, Leads to serious health issues, especially cardiovascular disease and especially cardiovascular disease and deathdeath

Excess carbs leads to storage as fat Excess carbs leads to storage as fat moleculesmolecules

Hormones are involved in the regulation Hormones are involved in the regulation of fat storageof fat storage

You are What you Eat You are What you Eat In addition to needing energy, you must In addition to needing energy, you must

take in certain molecules needed as raw take in certain molecules needed as raw materials (mostly C-skeletons) for materials (mostly C-skeletons) for important biomoleculesimportant biomolecules

essential nutrientsessential nutrients

–must obtain from environmentmust obtain from environment

–Can’t make on their ownCan’t make on their own

–Species specificSpecies specific

–Ex: vitamin C not important in all Ex: vitamin C not important in all species, very important in humans species, very important in humans

MalnourishmentMalnourishment Diet lacking in one or more essential Diet lacking in one or more essential

nutrientsnutrients

Even possible for an overnourished Even possible for an overnourished individual to be malnourishedindividual to be malnourished

Much more common in humans Much more common in humans than undernourishmentthan undernourishment

Amino AcidsAmino Acids Animals require about 20 amino acids for Animals require about 20 amino acids for

protein synthesisprotein synthesis Can make about half from raw materials Can make about half from raw materials

(provided enough nitrogen)(provided enough nitrogen) Essential Amino AcidsEssential Amino Acids Must be Must be

obtained in preassembled formobtained in preassembled form Protein deficiencyProtein deficiency

–Missing one or more amino acids in dietMissing one or more amino acids in diet–Most common form of malnourishmentMost common form of malnourishment

Complete/Incomplete ProteinsComplete/Incomplete Proteins Complete ProteinsComplete Proteins

– Provide all essential amino acidsProvide all essential amino acids

– Meat, eggs, cheese (animal products)Meat, eggs, cheese (animal products)

Incomplete ProteinsIncomplete Proteins– Lacking one or more essential amino acidsLacking one or more essential amino acids

– Corn, rice, etc all lack an essential amino Corn, rice, etc all lack an essential amino acidacidStaples in 3Staples in 3rdrd World Countries World Countries

Overcoming Incomplete ProteinsOvercoming Incomplete Proteins Eat a Eat a

complementary mix complementary mix of veggies that of veggies that cover the essential cover the essential amino acidsamino acids

Eating the right mix Eating the right mix of incomplete of incomplete proteins is as proteins is as effective as eating effective as eating complete proteinscomplete proteins

Fatty AcidsFatty Acids

Most fatty acids can be synthesizedMost fatty acids can be synthesized

There are a few essential fatty acids There are a few essential fatty acids (usually unsaturated)(usually unsaturated)

Deficiencies are rareDeficiencies are rare

VitaminsVitamins Required in relatively trace Required in relatively trace

(minimal) amounts(minimal) amounts However, deficiencies can have However, deficiencies can have

drastic effectsdrastic effects 13 vitamins essential to humans 13 vitamins essential to humans

–water-soluble vitamins water-soluble vitamins

–fat-soluble vitaminsfat-soluble vitamins

Water Soluble VitaminsWater Soluble Vitamins

Fat Soluble VitaminsFat Soluble Vitamins

MineralsMinerals Simple inorganic nutrientsSimple inorganic nutrients Usually required in small amountsUsually required in small amounts Ex: CaEx: Ca+2+2 and PO and PO44

-3-3 required for bones required for bones

Ex: Iron needed for hemoglobin, Ex: Iron needed for hemoglobin, cytochrome complex (ETC)cytochrome complex (ETC)

NaNa++,, KK++ and Cl and Cl-- needed for osmotic needed for osmotic balance and transportbalance and transport

MineralsMinerals

Types of NutritionTypes of Nutrition

–HerbivoresHerbivores (gorillas, cows, hares) (gorillas, cows, hares) eat mainly autotrophs (plants, algae)eat mainly autotrophs (plants, algae)

–CarnivoresCarnivores (sharks, hawks, spiders, (sharks, hawks, spiders, and snakes) and snakes) eat other animals eat other animals

–OmnivoresOmnivores (humans) (humans) consume consume animal and plant or algal matteranimal and plant or algal matter

Suspension Feeders Suspension Feeders sift small food sift small food

particles from the particles from the waterwater

Ex: baleen Ex: baleen whales, clamswhales, clams

Deposit Feeders (e.g., earthworms)Deposit Feeders (e.g., earthworms)

Eat their way through dirt or Eat their way through dirt or sediments extract partially decayed sediments extract partially decayed organic material consumed along organic material consumed along with the soil or sedimentswith the soil or sediments

Substrate FeedersSubstrate Feeders Live in or on their Live in or on their

food sourcefood source Ex: Maggots Ex: Maggots

consuming a consuming a decaying carcassdecaying carcass

Ex: Leaf Miner Ex: Leaf Miner (right) burrows (right) burrows through leafthrough leaf

Fluid FeedersFluid Feeders Suck nutrient-rich fluids from a living Suck nutrient-rich fluids from a living

host host Often considered parasitesOften considered parasites Ex: Mosquitoes and leaches suck blood Ex: Mosquitoes and leaches suck blood

from animalsfrom animals Ex: Aphids tap the phloem sap of plantsEx: Aphids tap the phloem sap of plants Ex: Hummingbirds and bees are good Ex: Hummingbirds and bees are good

fluid feeders (nectar)fluid feeders (nectar)

Bulk FeedersBulk Feeders Most animals eat Most animals eat

relatively large relatively large portions of food portions of food when availablewhen available

This is sort of a This is sort of a take it while you take it while you can get it approach can get it approach to nutrition b/c food to nutrition b/c food can be scarcecan be scarce

Ingestion Ingestion Take Food In Take Food In

Act of eatingAct of eating

First stage of food processingFirst stage of food processing

Food molecules cannot be used “as-is” Food molecules cannot be used “as-is” and must be digested in order for the and must be digested in order for the cells to make use of them as nutrientscells to make use of them as nutrients

Digestion Digestion Break Food Down Break Food Down

Why is food digested??Why is food digested??

–Polymers in food molecules too large to Polymers in food molecules too large to pass into cellspass into cells

–Macromolecules in food are not exactly Macromolecules in food are not exactly what makes up the animal eating themwhat makes up the animal eating themHowever, animals all use common However, animals all use common monomers to assemble monomers to assemble macromoleculesmacromolecules

DigestionDigestion Break food down into small, absorbable Break food down into small, absorbable

moleculesmoleculesPolysaccharides and disaccharides Polysaccharides and disaccharides are split into simple sugars.are split into simple sugars.

Fats are digested to glycerol and fatty Fats are digested to glycerol and fatty acids.acids.

Proteins are broken down into amino Proteins are broken down into amino acids.acids.

Nucleic acids are cleaved into Nucleic acids are cleaved into nucleotidesnucleotides

Enzymatic HydrolysisEnzymatic Hydrolysis Reverse process as dehydration synthesisReverse process as dehydration synthesis Enzymes are used to cleave polymers into Enzymes are used to cleave polymers into

monomersmonomers Specific enzymes digest the specific Specific enzymes digest the specific

classes of macromoleculesclasses of macromolecules Chemical digestion (enzymes) is generally Chemical digestion (enzymes) is generally

preceded by mechanical digestion preceded by mechanical digestion (chewing, gizzard) (chewing, gizzard)

Absorption and EliminationAbsorption and Elimination Useful nutrient molecules are absorbed Useful nutrient molecules are absorbed

and used by the animaland used by the animal

Molecules that have little use in the Molecules that have little use in the organism are eliminated as wasteorganism are eliminated as waste

DigestionDigestion Specialized organs perform the various Specialized organs perform the various

digestion of food moleculesdigestion of food molecules

Keeps organisms from digesting their own Keeps organisms from digesting their own cellscells

Intracellular DigestionIntracellular Digestion Food vacoules break down particles via Food vacoules break down particles via

hydrolytic enzymeshydrolytic enzymes Sole digestion of many protistsSole digestion of many protists

Food Vacuole DigestionFood Vacuole Digestion

Extracellular DigestionExtracellular Digestion

Takes place outside of cellsTakes place outside of cells Fungi release enzymes into the soil Fungi release enzymes into the soil

that digest their food before it enters that digest their food before it enters themthem

Allows smaller single-celled organisms Allows smaller single-celled organisms to consume larger food molecules than to consume larger food molecules than phagocytosisphagocytosis

Gastrovascular CavitiesGastrovascular Cavities Single opening Single opening

digestive systemsdigestive systems Food enters mouth, Food enters mouth,

is digested in GV is digested in GV cavity, and cavity, and undigested undigested material is material is eliminated back eliminated back through the mouththrough the mouth

Cnidaria, flatwormsCnidaria, flatworms

Alimentary Canals (complete digestive tube)Alimentary Canals (complete digestive tube)

Mouth, digestive tube (stomach, Mouth, digestive tube (stomach, gizzard, intestines), and anusgizzard, intestines), and anus

Runs in one direction, food processed Runs in one direction, food processed differently in different compartmentsdifferently in different compartments

Mouth Mouth Pharynx Pharynx Esophagus Esophagus Crop/Gizzard/Stomach (species dep.) Crop/Gizzard/Stomach (species dep.) Intestines Intestines Anus Anus

Alimentary CanalsAlimentary Canals

Human DigestionHuman Digestion

–5 to 10 seconds in esophagus 5 to 10 seconds in esophagus

–2 to 6 hrs in the stomach being 2 to 6 hrs in the stomach being partially digestedpartially digested

–5 to 6 hrs in small intestine (final 5 to 6 hrs in small intestine (final digestion and nutrient absorption) digestion and nutrient absorption)

–12 to 24 hours after consumption, 12 to 24 hours after consumption, undigested material eliminated undigested material eliminated through large intestine and anusthrough large intestine and anus

Human Digestive SystemHuman Digestive System

Levels of OrganizationLevels of Organization

Cells are the basic functional unitCells are the basic functional unit

Cells Cells Tissues Tissues Organs Organs Organ Organ Systems Systems Organism Organism

TissuesTissues Epithelial tissue covers the surface of the Epithelial tissue covers the surface of the

body and lines the inside of organs body and lines the inside of organs simple epithelium - simple epithelium - single layer of cells;single layer of cells;

stratified epitheliumstratified epithelium - multiple tiers of - multiple tiers of cellscells

The shapes of cells:The shapes of cells:

cuboidalcuboidal (like dice) (like dice)columnarcolumnar (like bricks on end) (like bricks on end)

squamoussquamous (flat like floor tiles) (flat like floor tiles)

MusclesMuscles Many muscles are involved in digestionMany muscles are involved in digestion Some are voluntarily controlled (skeletal Some are voluntarily controlled (skeletal

muscle) and others are involuntarily muscle) and others are involuntarily controlled (smooth muscle)controlled (smooth muscle)

Skeletal Skeletal Striated, voluntary, found in Striated, voluntary, found in muscles and other voluntarily controlled muscles and other voluntarily controlled sphincterssphincters

Smooth Smooth Not striated, involuntary, Not striated, involuntary, peristalsisperistalsis

Cardiac Cardiac Found in the heart, involuntary Found in the heart, involuntary

Oral Cavity (Mouth)Oral Cavity (Mouth) Begins physical (chewing) and chemical Begins physical (chewing) and chemical

digestion of fooddigestion of food Salivary amylase breaks down starchSalivary amylase breaks down starch Enzyme released in response to food Enzyme released in response to food

presencepresence Chewing increases surface area for Chewing increases surface area for

chemical digestionchemical digestion Saliva also lubricates food for passage Saliva also lubricates food for passage

through esophagusthrough esophagus

PharynxPharynx

Between the mouth and the esophagusBetween the mouth and the esophagus Epiglottis Epiglottis Flap of skin that keeps the Flap of skin that keeps the

bolus (food ball) from “going down the bolus (food ball) from “going down the wrong pipe”wrong pipe”

When swallowing, the epiglottis covers When swallowing, the epiglottis covers the trachea and diverts food into the the trachea and diverts food into the esophagusesophagus

EpiglottisEpiglottis

EsophagusEsophagus Top muscles are voluntary (part of Top muscles are voluntary (part of

swallowing you control)swallowing you control)

Involuntary series of muscle contractions Involuntary series of muscle contractions (peristalsis) move food from mouth to (peristalsis) move food from mouth to stomach after it passes into esophagus stomach after it passes into esophagus from pharynxfrom pharynx

StomachStomach Chemical and mechanical digestion Chemical and mechanical digestion

(involuntary) proceed in the stomach(involuntary) proceed in the stomach

Elastic walls and folds allow the stomach Elastic walls and folds allow the stomach to churn about 2 L of food/liquid at a timeto churn about 2 L of food/liquid at a time

Secretes gastric juice (pepsin + HCl) that Secretes gastric juice (pepsin + HCl) that chemically digestschemically digests

Gastric JuiceGastric Juice–HCl provides acidic environment for HCl provides acidic environment for

pepsin and kills bacteria ingested with pepsin and kills bacteria ingested with foodfoodHCl converts pepsinogen (inactive) to HCl converts pepsinogen (inactive) to pepsin (active)pepsin (active)

–Pepsin is an enzyme that hydrolyzes Pepsin is an enzyme that hydrolyzes proteinsproteins

–Chief cells secrete pepsinChief cells secrete pepsin

–Parietal cells secrete HClParietal cells secrete HCl

StomachStomach

Stomach lining replaced by mitosis every Stomach lining replaced by mitosis every three daysthree days

Lining of mucus keeps the pepsin from Lining of mucus keeps the pepsin from digesting the stomach walldigesting the stomach wall

H. pyloriH. pylori Acid-resistant bacteria that causes human Acid-resistant bacteria that causes human

ulcersulcers

Small IntestineSmall Intestine Food (now chyme) passes through the Food (now chyme) passes through the

pyloric sphincter into the small intestinepyloric sphincter into the small intestine Small intestine is about 6m (20feet) in Small intestine is about 6m (20feet) in

length in adult humanslength in adult humans Most of the digestion and absorption Most of the digestion and absorption

occurs in the small intestineoccurs in the small intestine Adapted to maximize absorptive surface Adapted to maximize absorptive surface

areaarea

DuodenumDuodenum First 25 cm of small First 25 cm of small

intestineintestine Chyme mixed with Chyme mixed with

digestive juices digestive juices from the pancreas, from the pancreas, liver, gall bladder, liver, gall bladder, and gland cells of and gland cells of the intestinal wallthe intestinal wall

pH becomes more pH becomes more basic than stomach basic than stomach was due to was due to pancreatic pancreatic secretionssecretions

BileBile

Produced by the liverProduced by the liver Stored in the gallbladderStored in the gallbladder Aid in the emulsification (digestion) Aid in the emulsification (digestion)

and absorption of fatsand absorption of fats

Digestive Enzyme Specificity (location and substrate)Digestive Enzyme Specificity (location and substrate)

Starch DigestionStarch Digestion Begins in the mouth with Begins in the mouth with salivary salivary

amylaseamylase Continues in the small intestine with Continues in the small intestine with

amylase.amylase. AmylaseAmylase breaks polysaccharides into breaks polysaccharides into

disaccharides (sucrose and maltose)disaccharides (sucrose and maltose)

–Maltase and sucrase then break them Maltase and sucrase then break them into monomers of glucose and/or into monomers of glucose and/or fructose for use in cellular respirationfructose for use in cellular respiration

Protein DigestionProtein Digestion TrypsinTrypsin is the major enzyme that is the major enzyme that

breaks down proteins in the breaks down proteins in the duodenumduodenum

Proteins are broken down into their Proteins are broken down into their amiono acidsamiono acids

Other enzymes act upon the Other enzymes act upon the polypeptides produced by trypsin if polypeptides produced by trypsin if trypsin doesn’t completely digest to trypsin doesn’t completely digest to amino acidsamino acids

Protein DigestionProtein Digestion TrypsinTrypsin is is

secreted as secreted as inactive inactive trypsinogen by trypsinogen by pancreaspancreas

Intestinal Intestinal enzymes activate enzymes activate trypsintrypsin

Nucleic Acid DigestionNucleic Acid Digestion

First, nucleases break down DNA and First, nucleases break down DNA and RNA into nucleotides RNA into nucleotides (Pi+sugar+base)(Pi+sugar+base)

Other enzymes then break down the Other enzymes then break down the nucleotides into Pi, sugars, and nucleotides into Pi, sugars, and nitrogenous bases for reassembly into nitrogenous bases for reassembly into new nucleotidesnew nucleotides

Fat DigestionFat Digestion Fat does not get digested until the Fat does not get digested until the

small intestinesmall intestine Bile released by the gallbladder Bile released by the gallbladder

emulsifies the fatsemulsifies the fats

–EmulsificationEmulsification Separate fats into Separate fats into tiny dropletstiny droplets

Lipases then hydrolyzes the fats into Lipases then hydrolyzes the fats into fatty acids and glycerolfatty acids and glycerol

Small IntestineSmall Intestine Most of the digestion occurs in the Most of the digestion occurs in the

duodenumduodenum

Jujenum and ileum function mainly as Jujenum and ileum function mainly as absorptive surfacesabsorptive surfaces

–Absorption of nutrients and waterAbsorption of nutrients and water

–Small intestine has approx. same Small intestine has approx. same surface area as a tennis court to surface area as a tennis court to increase absorptionincrease absorption

AbsorptionAbsorption Folds and projections increase the SI surface areaFolds and projections increase the SI surface area Villi and microvilli are projections that increase SAVilli and microvilli are projections that increase SA LactealsLacteals

–Networks of blood vessels (capillaries) that absorb nutrients Networks of blood vessels (capillaries) that absorb nutrients across intestinal wallacross intestinal wallOnly 2 layers of cells separate lacteals from lumen of intestineOnly 2 layers of cells separate lacteals from lumen of intestine

AbsorptionAbsorption Depending on the size and charge of the Depending on the size and charge of the

nutrient involved, absorption can either be nutrient involved, absorption can either be passive or active passive or active

People eating a good diet absorb about People eating a good diet absorb about 85% of the organic nutrients they 85% of the organic nutrients they consumeconsume

Cellulose (plant cell walls) is indigestible Cellulose (plant cell walls) is indigestible and becomes roughage of fecesand becomes roughage of feces

Digestion is a very energetically and Digestion is a very energetically and chemically efficient process chemically efficient process

Hormones and DigestionHormones and Digestion

The sight, smell, or taste of food The sight, smell, or taste of food causes the brain to send a causes the brain to send a chemical signal to the digestive chemical signal to the digestive organs to prepare to digestorgans to prepare to digest

Hormones in the various organs Hormones in the various organs cause the secretion of the cause the secretion of the necessary digestive juicesnecessary digestive juices

The Large Intestine (Colon)The Large Intestine (Colon) Major function is reabsorption of waterMajor function is reabsorption of water b/t SI and LI, 90% of Hb/t SI and LI, 90% of H22O reabsorbedO reabsorbed

Peristalsis moves feces through the Peristalsis moves feces through the colon towards the rectumcolon towards the rectum

DiarrheaDiarrhea Too little H Too little H22O reabsorbedO reabsorbed

ConstipationConstipation Too much H Too much H22O O

reabsorbedreabsorbed

Intestinal BacteriaIntestinal Bacteria E coli is the main bacteria found in the E coli is the main bacteria found in the

intestineintestine Most of the bacteria live off of excess Most of the bacteria live off of excess

nutrients and release vitamins for usnutrients and release vitamins for us Bacteria are also involved in the Bacteria are also involved in the

regulation of water reabsorptionregulation of water reabsorption

–This is why antibiotics can cause This is why antibiotics can cause diarrheadiarrhea

FecesFeces Feces contain the undigested Feces contain the undigested

materials being eliminated by the materials being eliminated by the organismorganism

They often contain a lot of cellulose They often contain a lot of cellulose and saltsand salts

They are stored in the rectum and They are stored in the rectum and eliminated through the anuseliminated through the anus

Two sphincters (one voluntary, one Two sphincters (one voluntary, one not) control defecationnot) control defecation

DentitionDentition

Teeth are adapted to the type of Teeth are adapted to the type of food the organisms consumefood the organisms consume

For example, horses have large For example, horses have large flat teeth for grinding grasses flat teeth for grinding grasses while wolves have sharp teeth to while wolves have sharp teeth to tear at prey fleshtear at prey flesh

Humans show intermediate Humans show intermediate dentition because we have dentition because we have evolved as omnivoresevolved as omnivores

DentitionDentition

Length of Digestive SystemLength of Digestive System Since vegetation Since vegetation

has cell walls, has cell walls, herbivores have herbivores have longer alimentary longer alimentary canals to allow for canals to allow for adequate nutrient adequate nutrient extractionextraction

Takes longer to Takes longer to extract nutrients extract nutrients from plantsfrom plants

SymbiosisSymbiosis Animals that do not have enzymes to Animals that do not have enzymes to

digest cellulose form relationships digest cellulose form relationships with bacteria that do have these with bacteria that do have these enzymesenzymes

–Ex: HorseEx: Horse The bacteria break down the cellulose The bacteria break down the cellulose

and the simpler sugars are absorbed and the simpler sugars are absorbed by the animalby the animal

RuminantsRuminants Deer, cattle, sheepDeer, cattle, sheep As the animal eats grasses, the As the animal eats grasses, the

grasses pass through structures grasses pass through structures (rumen, reticulum) where (rumen, reticulum) where microorganisms digest cellulosemicroorganisms digest cellulose

After being processed by After being processed by microorganisms, the food passes microorganisms, the food passes through to be fully digested and through to be fully digested and absorbedabsorbed

RuminantsRuminants