Unit 3: Digestion Flashcards
Homeostasis
Maintain steady state, equilibrium, through negative feedback (thermoregulation, pH, osmoregulation)
Set point > stimulus > sensor > response > set point
Exchange
High surface area = faster diffusion
Nutrients
Food- energy, building blocks
Essential nutrients:
Amino acid- protein
Fatty acid- lipids
Vitamins
Minerals
Digestion
Catabolic, breaking compounds down to raw building blocks (monomers)
Oral Cavity
Mechanical digestion (teeth)
Salivary glands- saliva, amylase (lubrication, antibacterial, pH buffer, chem digestion)
Tongue shapes bolus of food
Before Stomach
Epiglottis- elastic cartilage blocks off trachea when swallowing
Esophagus- sphincter guides food to stomach
Stomach Gastric juices
In Gastric Pits:
Parietal cells- make H+ and Cl-
Chief cells- make pepsinogen
(inactive forms)
Food triggers Gastrin. Gastrin activates Chief cells and Parietal cells, and HCL denatures proteins and turns pepsinogen into pepsin, which digests proteins. (positive feedback)
Stomach
Bolus becomes chyme, mucus lining buffers walls, stomach sphincter releases chyme into duodenum
After stomach (in duodenum), From pancreatic duct
Bicarbonate, trypsin/chymotrypsin, breaks proteins
Liver & Gallbladder
Detoxifies, regulates nutrients through negative feedback produces bile into duodenum (break down fats)
Gallbladder- stores concentrated bile
Small Intestine
Epithelium has villi (fingerlike projections) which have microvilli on the cell surface
Maximizes surface area for absorption of nutrients, which are packaged into water-soluble structures
Nutrients enter capillaries in villi, which feed into the hepatic portal vein (to liver for detoxification)
Cecum
“Dead end” in large intestine that houses bacteria which break down plant fibers/cellulose
Colon
Absorbs water through osmotic pressure
Positive feedback mechanism vs Negative feedback mechanism
Positive- amplifies a change
Negative- reduce a change
Temperature Regulation (Negative Feedback)
Body temp increases: Sweat releases heat, which cools body
Body temp decreases: Muscles shiver, which heats body
Blood Glucose Regulation (Negative Feedback)
Blood glucose increases: Pancreases secretes insulin, glucose gets stored as glycogen inside liver, blood glucose falls
Blood glucose decreases: Pancreas secretes glucagon, glycogen inside liver gets broken down, blood glucose rises
