blood sugar levels regulated by pancreatic hormones insulin and glucagon

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