Blood Sugar LevelsHomeostasis via Negative Feedback

Obesity may be gene related

• Leptin leptin levels appetite - loss of body fat leptin levels and appetite

and wt gain

• potential medications for obesity

• An animal whose diet is missing one or more essential nutrients is said to be malnourished.

Giraffe eats bone to get phosphorus nutrient

• Vegetarian diet may result in protein deficiency

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

• 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

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

– dietary fiber

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

• 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)

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

Minerals

• Essential inorganic elements

• Involved in a variety of metabolic processes

• Major minerals versus trace minerals

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

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

Salivary Glands

Salivary Glands

Saliva

watermucin

amylase

The Tongue

Taste Buds

papilla

taste bud

taste pore

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

• Many of the protein-digesting enzymes, such as aminopeptidase, are secreted by the intestinal epithelium, but trypsin, chymotrypsin, and carboxypeptidase are secreted in inactive form by the pancreas.– Another intestinal enzyme,

enteropeptidase, converts inactive trypsinogen into active trypsin.

– Active trypsin then activates the other two.

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

Fig. 41.18

Pancreatic Enzymestrypsin

chemotrypsin

carboxypeptidase

amylase

phospholipase

lipase

nucleases

lumenmuscle layers

foldsvilli

Intestinal StructureIntestinal Structure

epithelial cells

capillaries

lacteal

Intestinal VillusIntestinal Villus

stomach

duodenum pancreas

pancreatic duct

common bile duct

gallbladder

liver

Bilebile saltsbile salts

bile pigmentsbile pigments

Intestinal Membrane Enzymes

disaccharidasesdisaccharidasesaminopeptidaseaminopeptidase

dipeptidasesdipeptidasesnucleotidasesnucleotidasesnucleosidasesnucleosidases

cecum appendix

ascending colon

transverse colon

descending

colon

sigmoidal

colon

rectum

internal anal sphincter external anal sphincter

anal canal

• Dentition, an animal’s assortment of teeth, is one example of structural

variation reflecting diet.

Deep sea gulper

Large expandable stomach

• 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