BIO Exam 2: Digestion (1) Flashcards
Digestion: Gastrointestinal tract (GI)
Lots of hydrolysis reactions to depolymerize macromolecules
Mouth
Mechanical breakdown of food chewing with teeth and tongue
Increase of Surface Area-to-Volume ratio
Lysozyme cuts peptidoglycanin many bacterial cell walls
Salivary Amylase
cuts glucose a1 → 4 glucose bonds thus, starch is depolymerized to glucose
Salivary Lipase
cuts triglycerides to glycerol and free fatty acids
From Mouth to Stomach: Peristalsis
Wave-like contraction of muscle rings Food is pushed to the stomach
Stomach
gastroesophageal sphincter–>Ring of muscle that opens only briefly->Some digestion, little absorption–>Mucous cells secrete mucus thick material protects stomach cells–>Watery mixture stays in the stomach for hours–>Mixed by muscle contractions of stomach–>Small amounts leave through the pyloric sphincter
Stomach (specific)
Parietal Cells secrete HCl to acidify the stomach to pH2
Protects the body
Denatures proteins which also kills microbes
Helps dissociate large complexes
Pepsin Activation
Chief cells secrete an inactive enzyme, pepsinogen
Activated by acidic condition
Duodenum: Small intestine after stomach
Almost immediately joined by ducts (connections from pancreas liver gall bladder)
Exocrine Pancreas
The pancreas contains two secretory tissues:
Endocrine:
ductless
hormones to blood
Exocrine:
ducts
aids in digestion
Two key exocrine cell types:
Duct Cells (lining the duct)
neutralize acid
Acinar Cells (acinus = raspberry)digestive enzymes
Exocrine Pancreas (Specific)
Acinar Cells secrete digestive enzymes
Trypsin and chymotrypsin are secreted in an inactive form and activated in small intestine low specificity proteases
Pancreatic Amylase cuts glucose a1 → 4 glucose bonds
Pancreatic Lipasere moves fatty acids from triglycerides
Bile Salts
Hepatocytes (liver cells) produce bile
includes key bile salt
amphipathic
Produced continuously
Stored in gallbladder
Released upon eating
Break up fat globules
Higher surface area-to-volume ratio
