Blood sugar levels regulated by pancreatic hormones insulin and glucagon

Obtaining essential nutrients

Storing protein for growth

Can be obtained by eating a diet of corn and beans

Body cannot make these

Vitamins: non-energy foods, organic moleculesrequired in small amounts, regulate body functions

Minerals: non-energy foods, inorganic molecules required in small amounts, regulate body functions

FOOD TYPES & FEEDING MECHANISMS

Suspension feeders

Substrate feeders

Fluid feeders

Bulk feeders

Intracellular Digestion•Sponges•Heterotrophic protists

FOOD PROCESSING•Ingestion•Digestion•Absorption•Enzymatic hydrolysis

Extracellular Digestion

•Occurs within compartments that are continuous with the outside of the animal’s body

•Specialized cells secrete enzymes

•Gastrovascular cavity with single opening – Cnidarians

•Platyhelminthes?

•Alimentary canal - Nematodes, Annelids, Mollusks, Arthropods, Echinoderms, Chordates

Complete Digestive System:mouth, pharynx, crop, gizzard, intestine, anus

PHYSICAL DIGESTION

• Mastication – chewing• Deglutition – swallowing• Peristalsis – wave like muscle

contractions through alimentary canal

• Segmentation – mixing food & enzymes

• Emulsification – bile from liver breaking large lipids into small lipids

CHEMICAL DIGESTION

• Carried out by hydrolases• Proteins → amino acids

• Carbohydrates → disaccharides• Disaccharides →

monosaccharides• Lipids → glycerol + 3 fatty acids• Nucleic acids → nucleotides

Alimentary canal? Accessory organs?

Oral cavity: begins physical digestion (chewing) and chemical digestion of carbohydrates (salivary amylase)Note epiglottis & peristalsis

STOMACH•Begins breakdown of proteins•Gastrin•Pepsinogen → pepsin•HCl•Mucus•Chyme•Pyloric sphincter•Cardiac sphincter

•NOTE

Makes bile

Stores bile

Secretes sodium bicarbonate and enzymes

Accessory organs: liver, gall bladder, pancreas

Hormones:•Secretin•Cholecystokinin

Enzymatic Digestion - Human

Activation of protein digesting enzymes in small intestine

Break down large polypeptides into shorter chains

Enteropeptidase – triggers activation of enzymes

ABSORPTION OF NUTRIENTSCapillaries: monosacch., aa., minerals, vitamins, water, some glycerolLacteals: fatty acids & most glycerol

*

INTESTINESSmall Intestine:• Length (6 m); surface area (300 m2)• Duodenum (digestion)• Jejunum & Ileum (absorption)• Hepatic portal system Large Intestine (colon): • Ascending, Transverse, Descending,

Sigmoid• Cecum, Appendix, Rectum, Feces• Absorption of water• Bacteria

Dentition & Diet

•Canines – killing & ripping

•Incisors – biting

•Molars - grinding

Longer intestine for processing fibrous diet

Cecum – fermentation chamber housing symbiotic bacteria

Ruminant digestion – most elaborate adaptation of all herbivores; aided by symbiotic bacteria and protists