BIO12 - PROCESSES AND RANDOM STUFF

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What are the 4 main processes of digestion? (4)

• INGESTION: intake food

• DIGESTION: polymers → monomers

• ABSORPTION: absorb nutrients

• ELIMINATION: excrete waste

How does the liver, pancreas, and gall bladder help digestion (1) (1) [2] (1) [3]

• Liver makes bile

• Gall bladder stores bile

  • Released into duodenum from common bile duct

    • Digests fat

• Pancreas makes pancreatic juice

  • Released into duodenum from common bile duct

  • Neutralizes chyme

  • Chemically digests sugars, fats + proteins

Swallowing process (4)

• Tongue pushes bolus to throat

  • Triggers swallowing reflex

• Soft palate pushes upwards

  • Blocks nasal passages

• Bolus pushes epiglottis over glottis

  • Blocks trachea

• Upper esophageal sphincter relaxes

  • Food enters esophagus

What are the 2 types of digestion (2)

• Chemical

  • Uses enzymes

• Mechanical

  • Physically breaks food → smaller pieces

Role of epithelial cells in stomach (2)

• Secretes mucus

  • Stops it from eating itself

• Not enough or hole in coat = ulcer

  • Hole usually caused by H. pylori

Role of gastric glands in stomach (2)

• Secretes gastric juice into stomach

  • Responds to gastrin

• Digests proteins → polypeptides (hydrolysis)

  • Pepsin digests other enzymes

    • Ex. salivary amylase + pathogens

What is gastric acid made of + what does each components do (2)

• HCl

  • Makes pepsinogen acidic

• Pepsinogen

  • HCl breaks it down into pepsin

What does pepsin do in the stomach? (2)

• Digests proteins → polypeptides

• Digests enzymes

  • Ex. salivary amylase + pathogens

What causes high surface area in the small intestine? (2)

• Fold-ception

  • Microvilli → villi → folds

• Narrow diameter

  • Lower Vol:SA ratio = easier diffusion

    • Ex. enzyme secretion + food absorption

What forms the hepatic portal vein? (1)

• Fusion of capillaries from small intestine + spleen

Hepatic portal system (5)

1) Nutrients absorbed in small intestine with villi

• Ex. glucose, AAs, nucleotides

2) Nutrients gets absorbed into the capillaries

• Fuses into hepatic portal vein

3) Nutrients travels to liver through HPV

4) Liver screens + processes nutrients

5) Blood returns back to circulation via HPV

How are lipoproteins made? (2)

• Glycerol + fatty A. diffuse through villus

• Converted to fat, packed w/ cholesterol + coated w/ protein + sent to lacteal

  • At epithelial cells

• Empties in blood w/ lymph fluid

What do lipoproteins do? (1)

• Sent to cell that need fat

  • Fatty As, triglycerides, cholesterol

How does the pancreas secrete juice (2)

• Chyme in duodenum releases secretin into blood

• Secretin carried into pancreas

  • Stimulates production

What is pancreatic juice made of? (2)

• Bicarbonate

  • Reacts w/ HCl = pH 2.5 → 8-9

• Enzymes

  • Only works at pH 8-9

How does the body regulate blood sugar (1) (4) (2)

• Negative feedback loop

HIGH:

• Pancreas releases insulin

• Insulin simulates muscle, fat, + liver cells

• Increases transport of glucose out of blood

• Glucose enters cells → glycogen

LOW:

• Pancreas detects + releases glucagon

• Liver + muscle cells convert glycogen → glucose

What is intestinal juice made of + function (2)

• Made of enzymes + mucus

• Protects + lubricates lumen (inside of intestine)

What causes appendicitis? (3)

• Inside of appendix is blocked

• Infections in digestive tract

  • Virus, bacteria, or parasites

• Blocked/trapped stool between caecum + appendix

What does the large intestine do to chyme? (5)

• Absorbs H₂O, Na⁺, + others ions back into blood

  • Hardens chyme

• Bacteria (E. Coli) breaks down food more

  • Releases vitamin K (blood clotting), Bs, AA, + growth factors

  • Symbiotic relationship

• Moves chyme into rectum (peristalsis)

• Stretch receptors tell brain when rectum is full

• Feces leave through anus (peristalsis again)

Common ailments of large intestine (2) [2] (3) [2] (1)

CONSTIPATION:

• Not enough water in feces

• Food doesn’t move fast enough

  • Can be from low fiber

    • Fiber hold on to water

DIARRHEA:

• Too much water in feces

• Too much fiber, anxiety, laxatives, parasites, toxins

• Antibiotics

  • Kills “good bacteria”

  • Causes dehydration, hemorrhoids, loss of vitamins (E.coli) + salts

HEMORRHOIDS:

• Broken vein in rectum

Bile (4)

• Made in the liver

• Secreted into duodenum

• pH = 8

• Fat → fat droplets

  • Increase SA for lipase to interact

What path does bile take in the body (1)

• Gall bladder → bile duct → duodenum

How do the different components of pancreatic juice help with digestion? (2)

• NaHCO₃ neutralizes acidic chyme

• Enzymes digest proteins, sugars + fats

How does the stomach make chyme? (3)

• Mixes food w/ gastric acid

• Takes 3-4 hours

  • Depends on size + composition of food