Part 3

Question 1

what is the GI track?

Answer 1

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

Question 1

what are the FOUR properties of the GI track?

Answer 1

MOTILITY
SECRETION
INGESTION
ABSORBTION

Question 2

describe CEPHILIC digestion

Answer 2

PHYSICAL and CHEMICAL
begins in the mouth
simulated by SYMPATHETIC and PARASYMPATHETIC nervous system
amylase and lipase (no protein breakdown)

Question 3

describe GASTRIC digestion

Answer 3

secretory cells of gastric MUCOSA
influence of PARASYMPATHETIC nervous system
increases INTESTINAL and GLAND activity
relaxes SPHINCTERS
digestion of PROTEINS and FATS

Question 4

describe the SMALL INTESTINE

Answer 4

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

Question 5

describe the ACCESSORY ORGANS to DIGESTION

Answer 5

PANCREASE: contributes inactive DIGESTIVE ENZYMES
GALLBLADDER stores BILE made in the LIVER used for FAT DIGESTION

Question 6

what are the types of CARBOHYDRATES?

Answer 6

MONOSACCARIDES = glucose, fructose, and galactose
DISACCARIDE = sucrose, maltose and lactose
POLYSACCARIDES = starches, fiber, and glycogen

Question 7

describe LACTOSE INTOLERANCE

Answer 7

glucose and galactose transported by ACTIVE TRANSPORT
fructose absorbed by FACILLITATED diffusion
deficiency in LACTASES enzyme = lactose intolerance

Question 8

describe PEPTIDE and AMINO ACID transport

Answer 8

PROTEINS broken down in smaller PEPTIDES
PEPTIDASE breaks down peptides into AAs
transported via BLOODSTREAM to PRODUCE ENERGY or MAKE PROTEINS

Question 9

describe FAT EMULSIFICATION

Answer 9

BILE aids in lipid digestion through EMULSIFICATION
bile salts are AMPHIPHATIC
LIPASES act on emulsified fat

Question 10

how are LIPIDS ABSORBED and TRANSPORTED?

Answer 10

absorbed as FATTY ACIDS and MONOGLYCERIDES
reassembled into TRIGLYCERIDES and CHYLOMICRONS (first absorbed by LYMPHATIC system)
re-enter circulation near THORACIC DUCT near heart

Question 11

describe LARGE INTESTINE ABSORBTION

Answer 11

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

Question 12

describe substrate oxidation and ATP producing pathways

Answer 12

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

Question 13

describe ANAEROBIC respiration

Answer 13

ATP produced from phosphocreatine degradation
end product is lactate

Question 14

describe FAT energy storage

Answer 14

stored as triglycerides in adipocytes

Question 15

describe CARBOHYDRATE storage

Answer 15

glycogen in liver (150g)
muscle (350g)
blood (30g)

Question 16

describe PROTEIN storage

Answer 16

large potential energy
only used in starvation or caloric restriction

Question 17

describe the pros and cons of CARBS as FEUL

Answer 17

generate ATP faster than fat
generate ATP anaerobically
stores water

Question 18

describe the pros and cons of FAT as FEUL

Answer 18

doesn’t hold water
cannot produce ATP anaerobically
most abundant energy reserve

Question 19

what is the ABSORBATIVE state?

Answer 19

first 3-4 hours after a meal
nutrients are STORES (anabolism)

Question 20

what is the POSTABSORPTIVE state?

Answer 20

macronutrients are mobilized for energy (CATABOLIC)
glucose spared for NERVOUS system

Question 21

describe BLOOD GLUCOSE REGULATION

Answer 21

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

Question 22

how is GLUCOSE REGULATED?

Answer 22

INSULIN is released when glucose levels are ELEVATED
GLUCAGON released when glucose levels are LOW

Question 23

describe SUBSTRATE use during exercise

Answer 23

prolonged, lower intensity –> plasma derived substrates, mostly free fatty acids, also some blood glucose
increased intensity –> mobilize energy stores within muscle (glycogen and triglycerides)

Question 24

what are SINGLE NUCLEOTIDE POLYMORPHISMS (SNPs)?

Answer 24

a difference in a SINGLE NUCLEOTIDE
most frequent source of POLYMORPHIC changes
distinguishes one individual from another

Question 25

how does the GENOTYPE relate to MORTALITY?

Answer 25

increased inflammatory cytokines, such as IL-6
SNP in the promoter of IL-6 is associated with increased IL-6

Question 26

how does MITOCHONDRIAL DAMAGE relate to AGING?

Answer 26

damage to mitochondrial genome occurs 10x more frequently than nuclear genome
damages occurs from ROS
DNA polymerase gamma: proofreads and repairs DNA damage
errors in DNA replication become more frequent with age

Question 27

what is CALORIC RESTRICTION

Answer 27

reduction in food intake by 20-40%
severe food restriction extended healthy lifespan of rats
no evidence in humans