Part 3 Flashcards
what is the GI track?
vast body surface area exposed to external environment
sees FOOD as well as potentially TOXIC/infectious agents and has MECHANISMS to deal with them
MUSCULAR SPHINCTERS AND VALVES partially separate the tube
large SURFACE AREA to villi and microvilli
resident GUT MICROBIOME
INTRINSIC NERVOUS SYSTEM
what are the FOUR properties of the GI track?
MOTILITY
SECRETION
INGESTION
ABSORBTION
describe CEPHILIC digestion
PHYSICAL and CHEMICAL
begins in the mouth
simulated by SYMPATHETIC and PARASYMPATHETIC nervous system
amylase and lipase (no protein breakdown)
describe GASTRIC digestion
secretory cells of gastric MUCOSA
influence of PARASYMPATHETIC nervous system
increases INTESTINAL and GLAND activity
relaxes SPHINCTERS
digestion of PROTEINS and FATS
describe the SMALL INTESTINE
villi increases surface area
secretions into the lumen of the small intestine upon the opening of the pyloric sphincter (bicarbonate, digestive enzymes, bile)
digestive enzymes anchored on lumen
describe the ACCESSORY ORGANS to DIGESTION
PANCREASE: contributes inactive DIGESTIVE ENZYMES
GALLBLADDER stores BILE made in the LIVER used for FAT DIGESTION
what are the types of CARBOHYDRATES?
MONOSACCARIDES = glucose, fructose, and galactose
DISACCARIDE = sucrose, maltose and lactose
POLYSACCARIDES = starches, fiber, and glycogen
describe LACTOSE INTOLERANCE
glucose and galactose transported by ACTIVE TRANSPORT
fructose absorbed by FACILLITATED diffusion
deficiency in LACTASES enzyme = lactose intolerance
describe PEPTIDE and AMINO ACID transport
PROTEINS broken down in smaller PEPTIDES
PEPTIDASE breaks down peptides into AAs
transported via BLOODSTREAM to PRODUCE ENERGY or MAKE PROTEINS
describe FAT EMULSIFICATION
BILE aids in lipid digestion through EMULSIFICATION
bile salts are AMPHIPHATIC
LIPASES act on emulsified fat
how are LIPIDS ABSORBED and TRANSPORTED?
absorbed as FATTY ACIDS and MONOGLYCERIDES
reassembled into TRIGLYCERIDES and CHYLOMICRONS (first absorbed by LYMPHATIC system)
re-enter circulation near THORACIC DUCT near heart
describe LARGE INTESTINE ABSORBTION
any unabsorbed nutrients, hormones, fibre, microbes, cellular debris, excretion products from the liver
absorbs WATER and SIMPLE IONS
MICROBES digest and absorbs chemicals via FERMENTATION
produce SOME VITAMINES (K and B) as a byproduct of metabolism
produce gasses during digestion
describe substrate oxidation and ATP producing pathways
GLUCOSE and FATTY ACID metabolism produce most ATP
some ATP produced by GLYCOLOSIS and KREBS CYCLE
produce NADH and FADH2 which supply PROTONS and ELECTRONS to ETC
describe ANAEROBIC respiration
ATP produced from phosphocreatine degradation
end product is lactate
describe FAT energy storage
stored as triglycerides in adipocytes
describe CARBOHYDRATE storage
glycogen in liver (150g)
muscle (350g)
blood (30g)
describe PROTEIN storage
large potential energy
only used in starvation or caloric restriction
describe the pros and cons of CARBS as FEUL
generate ATP faster than fat
generate ATP anaerobically
stores water
describe the pros and cons of FAT as FEUL
doesn’t hold water
cannot produce ATP anaerobically
most abundant energy reserve
what is the ABSORBATIVE state?
first 3-4 hours after a meal
nutrients are STORES (anabolism)
what is the POSTABSORPTIVE state?
macronutrients are mobilized for energy (CATABOLIC)
glucose spared for NERVOUS system
describe BLOOD GLUCOSE REGULATION
normal fasting glucose: 4.5-5mmol/L
free fatty acid range: 0.2-2mmol/L
HYPERGLYCEMIA: glucose > 7mmol/L
HYPOGLYCEMIA: glucose < 3.5 mmol/L
how is GLUCOSE REGULATED?
INSULIN is released when glucose levels are ELEVATED
GLUCAGON released when glucose levels are LOW
describe SUBSTRATE use during exercise
prolonged, lower intensity –> plasma derived substrates, mostly free fatty acids, also some blood glucose
increased intensity –> mobilize energy stores within muscle (glycogen and triglycerides)
