(1) Digestion Flashcards
Feeding Mechanisms
- Suspension feeding/ filter feeding (porifera)
- Deposit Feeding (annelida)
- Selective Feeding
Digestive Systems
- Incomplete
- Complete
Incomplete Digestive System
only one opening =mouth/anus
Example: planaria, cnidaria
Complete Digestive System
Separate anus and mouth, one way flow
Example: mollusks, annelids
Intracellular Digestion
Protista, Porifera
Extracellular Digestion
Arthropoda, Chordata
Intracellular & Extracellular Digestion
Cnidaria, planaria, roundworm
Hydrolases
Hydrolytic enzymes that break organic molecules by addition of water
Food movement through alimentary canal
- Cilia: Platyhelminthes, Nematoda, most mollusks
- Segmentation: mixing in intestine and stomach
- Peristalsis (around/spreading): movement through intestine
Metazoan Alimentary Canal
- Reception
- Conduction
- Storage and early digestion
- Grinding
- Terminal digestion and absorption
- Water absorption, concentration of solids
Receiving (alimentary canal)
a) ingestion, chewing, swallowing
b) salivary gland secretions
- lubricate
- initial hydrolysis
c) avoid choking
-epiglottis
Conduction and storage (alimentary canal)
a) transport to the stomach
b) crop- storage in many invertebrates and birds
Grinding & Early digestion (alimentary canal)
a) gizzard (grinding)
-muscular stomach subdivision
- birds and annelids, insects
- stones and grit swallowed, or hard lining
b)stomach (initial protein digestion)
- Cellulase not produced by metazoans, endosymbionts provide for some
- Gastric Juices: pepsin and HCL
Pepsin
splits protein
HCL Gastric Juice
kills bacteria, activates pepsin
Terminal Digestion & absorption
the small intestine does MOST digestion/breakdown and absorption
- pancreatic juice
- bile
- membrane enzymes
- absorption
Bicarbonate (Pancreatic Juice)
neutralizes acidic chyme = liquified food
Trypsin/chymotrypsin (Pancreatic Juice)
proteases = protein digestion
Lipase (Pancreatic Juice)
lipids fatty acids and glycerol
Amylase (Pancreatic Juice)
carbohydrates
Nucleases (Pancreatic Juice)
RNA and DNA, nucleotides
Aminopeptidase (Membrane Enzymes)
terminal amino acids. breaking protein to amino acids
Sucrase (Membrane Enzymes)
sucrose -> glucose + fructose
Lactase (Membrane Enzymes)
lactose -> glucose + galactose
Alkaline Phosphate (Membrane Enzymes)
phosphates compounds
Absorption
- Passive transport
- Active Transport
Water absorption & solids concentration (alimentary canal)
large intestine
Regulation of Food intake
- Hypothalamus (hunger center), monitors blood glucose
- Stretching of stomach and duodenum
- Brown fat (placental mammals): nonshivering thermogenesis
Nutritional Requirements
- Carbohydrates: energy and building block
- Protein: mostly for building blocks. Amino Acids = essential, we have to ingest it
- Lipids: energy and building block
- Minerals: anion and cations; building blocks, physiology
- Vitamins: simple organic molecules essential in diet
- Water: solvent
