ch 5 nutrition - vertebrate physiology · 2015-01-05 · 1/5/15 2 protein$func.on$ 1....

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Part 2: Food, Energy, Temperature

Chapter 5: Nutri:on, Feeding,

Diges:on

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What is nutri.on? •  Study of how organisms use external sources to synthesize chemicals that make up their bodies – How bodies convert food into energy for cell growth and repair

Nutri.on •  Study of how organisms use external sources to synthesize chemicals that make up their bodies Nutrients that

provide energy: 1.  Proteins 2.  Lipids 3.  Carbohydrates 4.  Vitamins 5.  Minerals

Rela.ve amounts of 5 main chemicals in average human

Nutri.on •  Study of how organisms use external sources to synthesize chemicals that make up their bodies Nutrients that provide

energy: 1.   Proteins 2.  Lipids 3.  Carbohydrates 4.  Vitamins 5.  Minerals


Protein •  Made up of amino acids linked with pep.de bonds – Polypep.des (short strings)

– Dipep.des (2 amino acids)

– Tripep.des (3 amino acids)

•  Sequence of amino acids determines protein shape and func.on

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Protein func.on 1.  Speed and regulate biochemical reac.ons –  Enzymes

2.  Fuel locomo.on (muscles) 3.  Determine structure of .ssues (collagen, kera.n) 4.  Control cell membrane func.on and/or

permeability –  Channels, receptors

5.  Transport oxygen (hemoglobin and myoglobin) 6.  An.bodies

Protein challenges 1.  Nitrogen is required for

protein synthesis, but is limi.ng in most ecosystems – “N fixers” convert N to useable form

Protein challenges 1.  Nitrogen is required for

protein synthesis, but is limi.ng in most ecosystems – “N fixers” convert N to useable form

2.  Timing of inges.on –  Not as important as

previously thought

Protein challenges 3.  20-‐22 amino acids

necessary for cell func.ons, but we can’t synthesize all of them –  Complex structure

•  9-‐10 essen:al amino acids must be ingested

•  11-‐12 Non-‐essen:al amino acids can be synthesized •  Condi.onally non-‐essen.al à synthesized under normal metabolic condi.ons

Nutri.on •  Study of how organisms use external sources to synthesize chemicals that make up their bodies Nutrients that provide

energy: 1.  Proteins 2.   Lipids 3.  Carbohydrates 4.  Vitamins 5.  Minerals


Lipids •  Waxes, phospholipids, sterols – Triglycerides: fats, oils

•  Most are fa_y acids – Hydrocarbon chains

•  Degree of satura.on and posi.on of double bond defines func.on – Saturated – all single bonds – Unsaturated – 1 double bond – Polyunsaturated – 2+ double bonds

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Lipid func.ons 1.  Main component of cell membrane

Lipid func.ons 2.  Controls permeability of cell membrane –  Slows evapora.ve water loss –  Allows animals to live on land

Lipid func.ons 3.  Storage compound –  Used for energy

Lipids •  Synthesized from ingested carbohydrates and proteins – Store excess as body fat – This is how we can gain body fat from ea.ng sugar

•  Naming based on posi.on of double bonds •  Essen:al faEy acids can’t be synthesized – Omega-‐3 and Omega-‐6


provide energy: 1.  Proteins 2.  Lipids 3.   Carbohydrates 4.  Vitamins 5.  Minerals


Carbohydrates •  Sugars are easy to obtain – Monosaccharide (fructose, glucose) – Disaccharides (Sucrose) – Polysaccharide (cellulose, starch)

•  Easy to synthesize (from proteins, lipids)

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Carbohydrate diversity defines func.on

1.  Structural support and shape –  Chi.n, cellulose

2.  Storage –  Starch, glycogen

3.  Energy source –  CNS, ATP produc.on

4.  Transport –  Glucose (blood sugar) –  Brings stored compounds to area where used


provide energy: 1.  Proteins 2.  Lipids 3.  Carbohydrates 4.   Vitamins 5.   Minerals


Vitamins •  Organic compounds required in small amounts •  None can be synthesized – Various dietary sources for different vitamins

•  Serve MANY physiological needs!!

Minerals •  Elements that occur in enzymes and other proteins not found in cell cytoplasm –  Iodine for thyroid func.on – Phosphorous to synthesize lipids, nucleic acids, and bone

•  40% of proteins are metalloproteins

The great Serenge. migra.on: A quest for minerals?

•  Wildebeests and zebras migrate 100+ miles every year

•  Soils of SE are rich in necessary minerals – Ca for lata.ng – P and Na for developing young

Video

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Feeding •  Process of obtaining and inges.ng food •  Three main considera.ons

1.  Nutri.onal needs 2.  Feeding mechanisms •  How individuals acquire nutri.onal needs •  Feeding apparatus

3.  Ability to process nutrients

Behavioral selec.on based on nutri.onal needs

•  Wolf spiders preferen.ally select flies to balance their intake of protein and lipid

Feeding •  Process of obtaining and inges.ng food •  Three main considera.ons

1.  Nutri.onal needs 2.  Feeding mechanisms •  How individuals acquire nutri.onal needs •  Feeding apparatus

3.  Ability to process nutrients

Feeding mechanisms •  Mechanism .ed to feeding apparatus •  3 main mechanisms of feeding

1.  Target and ingest individuals 2.  Suspension feeding 3.  Symbio.c microbes

•  Apparatus – Carnivores à teeth – Birds à bills

•  Subtle differences in apparatus allow exploita.on of different food items – Bill shape allows feeding on different seed types

– Grazers– tooth/jaw/lips allow feeding on different plants

Feeding: Individual food items Feeding: Suspension feeding •  Baleen whales, blue whales, whale sharks feed on suspended objects

•  Challenge: Gemng enough food!!

•  Most are generalists – Small but numerous prey

•  Eat lower on food chain – Greater E per unit .me

VIDEO

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Feeding: Suspension feeding •  Suspension feeders use variety of mechanisms – Filter feeders: Baleen whale

VIDEO1

Feeding: Symbio.c microbes •  Foregut and Hindgut fermenta.on

•  We’ll come back to this....

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Diges.on and Absorp.on •  Diges.on: Breakdown of food by enzymes and distribu.on of component chemicals to body .ssues

PROTEINS AMINO ACIDS

VARIOUS CELLULAR PROCESSES

•  Absorp.on: Molecules broken down in diges.on enter living .ssues

Components of the vertebrate diges.ve system

1.  Headgut 2.  Foregut 3.  Midgut 4.  Hindgut


1.   Headgut: Mouth, teeth, etc –  Capture/engulf

food –  Prepare food for

diges.on –  Feeding apparatus

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1.  Headgut 2.   Foregut –  Esophagus: moves

food to stomach –  Stomach: ini.ates

protein diges.on; stores and breaks down food

–  Muscles, acids, diges.ve enzymes aid breakdown


1.  Headgut 2.  Foregut 3.   Midgut: Small

intes:ne –  Diges.on of most

proteins, lipids, and carbohydrates

–  Absorp.on across cell membranes via microvilli


1.  Headgut 2.  Foregut 3.  Midgut 4.   Hindgut: Large

intes.ne –  Stores waste

products –  Completes

absorp.on


1.  Headgut 2.  Foregut 3.  Midgut 4.  Hindgut 5.   Pancreas –  Stomach acids

trigger produc.on and secre.on of diges.ve enzymes


1.  Headgut 2.  Foregut 3.  Midgut 4.  Hindgut 5.  Pancreas 6.   Liver –  Produces and

secretes bile to digest lipids

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Feeding: Fermenta.ve breakdown •  Herbivores •  Diges.on begins in 4-‐chambered stomachs

•  Fermenters have long intes.nes

•  Mammals don’t produce cellulase

Feeding: Fermenta.ve breakdown •  Fermenta.on: Enzyme-‐catalyzed reac.ons that occur without oxygen

•  Anaerobic microbes (fermenters) thrive in gut lumen – Aid in breakdown of cellulose

Feeding: Fermenta.ve breakdown •  Fermenta.on based on where microbes live:

1.  Foregut fermenters –  Herbivores: Sheep,

ca_le, antelope, deer

2.  Hindgut fermenters –  Rabbits, horses,

ostriches, chickens, lizards, turtles

Foregut fermenta.on: Microbe func.ons

1.  Produce cellulase (enzyme that breaks down cellulose)

2.  Synthesize B vitamins and essen.al amino acids –  Remember, we (and herbivores)

can’t make these

3.  Recycle waste products –  Microbes breakdown urea and use

products (NH3) to synthesize proteins

Cellulose

SCFAs, CO2, CH4

N in Urea NH3 Proteins, amino acids

Hindgut fermenta.on: Microbe func.ons

•  Same func.ons, but in enlarged hindgut –  Cecum or colon

•  Fermenta.on occurs aqer moving through stomach and small intes.ne...? –  Waste products of

fermenta.on (proteins) must be eaten again

N in Urea NH3 Proteins, amino acids

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Diges.on and absorp.on •  Nutri.onal value of food is only as good as your ability to digest and absorb the food – Diges.on on it’s own isn’t enough!

•  Diges.on process catalyzed by diges:ve enzymes

Diges.ve enzymes •  Produced throughout diges.ve system

Diges.ve enzymes •  Specific to type of bond they can break – Lactase enzyme breaks bonds in lactose molecules – People who don’t produce lactase can’t break down lactose

Diges.ve enzymes •  Specific to type of nutrient they breakdown

•  Carbohydrate diges.on: disaccharidases •  Protein diges.on: pep.dases

•  Lipid diges.on: lipases, bile salts

Diges.ve enzymes

•  Proteins are so diverse, a single protein may require up to three enzymes to break down!

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Absorp.on •  Transport of chemicals across epithelial cells in diges.ve system

•  Greater surface area à faster absorp.on •  Microvilli on intes.nal lumen

•  Can occur via simple diffusion, facilitated diffusion, or 2° ac.ve transport (requires E) •  Depends on solubility of molecule

Nutri.onal responses at all .me scales Time scale Response(s) Example

ACUTE •  Secrete diges.ve enzymes, acids GI tract func.on aqer a meal

CHRONIC •  Dietary changes can alter amount/type of diges.ve enzyme •  Can alter nutri.onal value of food (more/less available)

1.  Low carb diets à reduce produc.on of carb-‐diges.ng enzymes

2.  Size of GI tract expand/contract based on species requirement

EVOLUTIONARY •  Individuals or popula.ons altered gene expression •  New field of NUTRITIONAL GENOMICS

1.  Diet-‐regulated genes (Type II diabetes)

2.  Hummingbirds produce more sucrase

DEVELOPMENTAL •  Genes expression turned on/off Lactose aqer weaning

BIOLOGICAL CLOCK •  Daily/seasonal changes in enzyme produc.on

1.  Rats -‐ more disaccharidases at night (nocturnal ea.ng)

2.  Seasonal fa_ening of migra.ng birds

ch 5 nutrition - vertebrate physiology · 2015-01-05 · 1/5/15 2 protein$func.on$ 1....

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