What are nutrients?• Essential substances that your body

needs in order to grow and stay healthy

What is a Nutrient?

Nutrients

• Some provide energy. • All help build cells and

tissues, regulate bodily processes such as breathing.

• No single food supplies all the nutrients the body needs to function.

Nutrients in the Human Diet

• Macronutrients– Water– Amino Acids and Proteins– Lipids– Carbohydrates

• Micronutrients– Vitamins– Minerals

Six categories of nutrients:

Healthy Diets Require:

• Water

• Carbs, Proteins, Lipids, Amino Acids

• Vitamins:

- water-soluble (thiamine, riboflavin, folic acid)

- fat-soluble (Vitamin A, D, E, K)

• Minerals (Fe, Ca, P, Na, K)

Water• Solvent in which the chemistry of life occurs

– cell chemistry occurs in an aqueous medium– water carries essential nutrients to cells– water carries metabolic wastes away from cells– hydrolysis & dehydration reaction– stabilizes body temp

Carbohydrates

• Energy Metabolism– catabolism of glucose during cellular

respiration yields ATP for energy-requiring activities

– glucose stored as glycogen in the liver and muscle cell fibers

Carbohydrates• Dietary Fiber

– water-insoluble fiber adds bulk to fecal matter facilitating its passage through and elimination from the digestive system

– water-soluble fiber may absorb dietary cholesterol, reducing its absorption by the digestion tract

Wheat Seed

Wheat Seed

Lipids• Triglycerides (Fats)

– energy storage molecules– protect and cushion delicate body organs– source of the raw materials for the

construction of phospholipids– unsaturated versus saturated fats

Lipids• Saturated Fats

– Solid at RT– Milk, cheese, meat– Not good for you

• Unsaturated Fats– Liquid at RT– Distorted double bounds– Canola, olive, peanut oil– Better choice

Lipids• Steroids (e.g., cholesterol)

– precursor molecules for steroid hormones, vitamin D, bile salts

– fundamental component of plasma membranes (influence membrane fluidity)

– HDL-cholesterol versus LDL-cholesterol

Proteins

• Enzymes • Structural proteins (shape and

form of cells and tissues)• Hormones• Immunoglobulins (antibodies)

Essential Amino Acids

• Tryptophan• Methionine• Valine• Threonine

• Phenylalanine• Leucine• Isoleucine• Lysine

• Histidine(infants)

Complete ProteinsVersus

Incomplete Proteins

• Vegetarian diet may result in protein deficiency

• Need essential amino acids– beans lysine – corn the methionine

Vitamins• Organic compounds needed by

the body in small, but essential amounts

• Cannot be synthesized by the body in sufficient amounts

• Function in a variety of ways in metabolic reactions

• Thirteen known vitamins

Water-Soluble Vitamins

vsWater-Insoluble

Vitamins

Water-Soluble Vitamins

Pantothenic acid

Biotin

B12 (cyanocobalamin)

Folic acid

C (ascorbic acid)

B1 (thiamin)

B2 (riboflavin)

Niacin

B6 (pyridoxine)

Water-Insoluble Vitamins

A (retinol)DEK

Minerals

• Essential inorganic elements• Involved in a variety of

metabolic processes• Major minerals versus trace

minerals

Major MineralsCalcium

PhosphorusMagnesiumSodiumPotassiumChlorine

Trace Minerals

IronIodineFluorideZincCopper

Manganese

Cobalt

Selenium

Chromium

• An animal whose diet is missing one or more essential nutrients.

Giraffe eats bone to get phosphorus nutrient

Malnourishment

Giraffe eats bone to get phosphorus nutrient

• Impaired cognitive development

• Won’t attain full height

• More susceptible to disease and infection

Malnourishment

• Healthy diets requires essential amino acids otherwise protein synthesis is retarded.

• Special adaptations during molting (non-feeding time)– uses their muscle proteins

as a source of amino acids to make new proteins

Feeding Types:

• Herbivores

• Carnivores

• Omnivores

• Detritivores

Some Feeding TypesSome Feeding TypesMany species don’t fit into convenient categories

• Algal Grazers and Browsers• Suspension Feeding• Filter Feeding• Deposit Feeding• Benthic Animal Predators• Plankton Pickers• Corallivores• Piscivores• Omnivores• Detritivores• Scavengers• Parasites• Cannibals• Ontogenetic dietary shifts

Fig. 41-6a

Humpback whale, a suspension feeder

Baleen

Fig. 41-6b

Leaf miner caterpillar,a substrate feeder

Caterpillar Feces

Fig. 41-6c

Mosquito, a fluid feeder

Fig. 41-6d

Rock python, a bulk feeder

Deep sea gulper

Large expandable stomach

Overview of Food Processing

The four main stages of food processing:

1. Ingestion

2. Digestion

3. Absorption

4. Elimination

Digestion occurs in specialized compartments

The simplest digestive compartments are food vacuoles; it is a process termed intracellular digestion

Gastrovascular cavity

Complete Digestive Tracts (Alimentary Canal)

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 41.13

Digestive ProcessDigestive Process

1.1. IngestionIngestion2.2. PropulsionPropulsion3.3. Mechanical DigestionMechanical Digestion

• MasticationMastication• Churning food in stomachChurning food in stomach

4.4. Chemical digestionChemical digestion5.5. AbsorptionAbsorption6.6. DefecationDefecation

incisors

cuspid

premolars

molars

TeethTeeth

enameldentinpulp cavity

root canal

bone

blood vessels

crown

neck

root

• Dentition, an animal’s assortment of teeth, is one example of structural variation reflecting diet.

Salivary GlandsSalivary Glands

Salivawatermucin

amylase

The Tongue

Taste BudsTaste Buds

Circumvallate Papilla

Filiformpapilla

Fungiformpapilla

Connective tissue Tongue epithelium

Salty- metallic ions

Sweet- sugarSweet- sugar

Sour- HSour- H++

Bitter- alkaloidBitter- alkaloid

Why are they important?

Umami- savory/meatyUmami- savory/meaty

Peristalsis

The Stomach

esophaguscardiac sphincter

pyloric sphincterduodenum

Stomach Secretions

Gastric Gland:Gastric Gland:Mucus cellsMucus cellsChief cellsChief cells

Parietal cellsParietal cells

Mucous neck cells- found in upper region of gastric glands produce• mucous

 Parietal cells- in gastric gland of mucosa

produce• HCl – kills most bacteria• Intrinsic factor (required for absorption of vit. B12 in sm intestine, which is needed for producing mature erythrocytes)

 Zymogenic (chief) cells-

produce• pepsinogen (inactive form of pepsin, which becomes active in presence of HCl) • rennin (milk digestion in children) protein digestion

 

Enteroendocrine cells in stomach mucosaproduces:

• Gastrin- regulates stomach secretions and mobility

• Histamine- activates parietal cells to release HCl• Endorphins- natural opiates• Serotonin- causes contraction of stomach

muscle• Cholecystokinin (CCK)- (in duodenal mucosa)

many functions and affects many organs• Somatostatin- (stomach and duodenal mucosa)

- inhibits gastrin, pancreatic secretions, inhibits GI blood flow in sm intestine…

Gastric ulcers- erosion of stomach wall; pain occurs 1-3 hrs after eating--- new research90% of recurrent ulcers due to bacterial infection (Helicobacter pylori), which destroys mucous protective barrier; use antibiotic therapy to kill bacteria

Pancreatic Enzymestrypsin

chemotrypsin

carboxypeptidase

amylase

phospholipase

lipase

nucleases

lumenmuscle layers

foldsvilli

Intestinal StructureIntestinal Structure

epithelial cells

capillaries

lacteal

Intestinal VillusIntestinal Villus

Intestinal Membrane Enzymes

disaccharidasesdisaccharidasesaminopeptidaseaminopeptidase

dipeptidasesdipeptidasesnucleotidasesnucleotidasesnucleosidasesnucleosidases

Figure 41.16 The duodenum

Bilebile saltsbile salts

bile pigmentsbile pigments

cecum appendix

ascending colon

transverse colon

descending

colon

sigmoidal

colon

rectum

internal anal sphincter external anal sphincter

anal canal

• The length of the vertebrate digestive system is also correlated with diet.

• Cellulose is difficult to digest• Termites have symbiotic

bacteria• Some bacteria and protists

have enzymes that hydrolyze cellulose

Symbiotic microorganisms aid in digestion

Moment of Zen