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ISAP > Break It Down And Suck It Up > Flashcards

Break It Down And Suck It Up Flashcards

1
Q

What types of regulation are there in the digestive system?

A
  • Nervous (local and general).

- chemical (production of hormones, production of paracrine chemicals).

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2
Q

What does parasympathetic input stimulate?

A
  • muscle contraction.

- secretion.

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3
Q

What does sympathetic input regulate?

A
  • muscle contraction.
  • secretion.
  • decreases blood flow to GIT.
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4
Q

Enzymes of chemical digestion in the mouth?

A
  • a-amylase.

- lingual lipase.

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5
Q

Function of a-amylase in oral cavity?

A

Begins starch digestion into disaccharides maltose and isomaltose.

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6
Q

Function of lingual lipase?

A

Begins breakdown of triglycerides into fatty acids and glycerol.

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7
Q

What are the extrinsic paired salivary glands?

A

Parotid, submandibular and sublingual.

-produce 1-1.5L/day.

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8
Q

What are the paired extrinsic salivary gland secretion controlled by?

A

Mainly parasympathetic nervous system:

  • facial nerve.
  • glossopharyngeal nerve.
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9
Q

Composition of extrinsic paired salivary gland secretions?

A
  • 99.5% water, 0.5% solutes.

- salts, mucin, lysozyme, amylase, lipase, IgA.

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10
Q

Intrinsic salivary glands (lingual and buccal)?

A

The tongue and oral cavity mucosa.

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11
Q

What are the functions of saliva?

A
  • lubricates food, helps form boils for easier swallowing.
  • dissolves food chemicals for tasting.
  • bicarbonate buffers acidic foods.
  • chemical digestion (enzymes).
  • antomicrobial: lysozyme, IgA, defending.
  • protects mouth from infection with its rinsing action.
  • calcium and phosphate for maturation of teeth enamel.
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12
Q

What gastric gland cells are in the stomach?

A
  • mucous neck.
  • parietal (oxyntic).
  • chief (zymogenic).
  • endocrine.
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13
Q

Parietal cell secretion?

A

HCL and intrinsic factor.

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14
Q

Chief cell secretion?

A

Pepsinogen, gastric lipase.

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15
Q

Endocrine cell secretions in the stomach?

A

Regulatory hormones.

  • g cells: secrete gastrin.
  • enterocheomaffin-like cells.
  • somatostatin-containing cells.
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16
Q

Enterochromaffin-like cells function.

A

Histamine stimulates acid secretion.

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17
Q

Somatostatin-containing cells.

A

Secrete somatostatin that inhibited gastrin and insulin secretion.

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18
Q

What is chyme?

A

Ingested food plus stomach secretions.

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19
Q

Role of mucus in stomach?

A
  • protects from acidic chyme and enzyme pepsin.

- irritation of stomach mucosa causes greater mucus.

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20
Q

Role of intrinsic factor in stomach?

A
  • binds with vitamin B12 and helps its absorption across terminal ileum.
  • B12 necassary for DNA synthesis.
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21
Q

Role of HCL in stomach?

A
  • kills bacteria.
  • stops carbohydrate digestion by inactivating salivary amylase.
  • denatures proteins.
  • helps convert pepsinogen to pepsin.
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22
Q

Role of pepsinogen in the stomach?

A
  • packaged in zymogen granules, released by exocytosis.

- pepsin catalyses breaking of covalent bonds in proteins.

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23
Q

Phases of stomach digestion (3)?

A
  • cephalic phase.
  • gastric phase.
  • intestinal phase.
24
Q

Outline the cephalic phase of digestion.

A
  1. Sight, taste, smell, thought of food, tactile sensations in mouth -> stimulate medulla oblongata.
  2. Impulses via vagus nerves to stomach -> enteric plexus neurons activated.
  3. Stimulate secretion of HCL and pepsin, gastrin and histamine (paracrine).
  4. Gastrin travels via circulation back to stomach -> gastrin and histamine stimulate further secretion of HCL and pepsin.
25
Q

What is the role of the cephalic phase?

A

Prepares stomach for food.

Excitatory-minutes

26
Q

Outline the gastric phase of digestion (excitatory and continuing 3-4 hours).

A
  1. Distension of stomach activates parasympathetic reflex action potentials via vagus nerves to medulla oblongata.
  2. medulla oblongata stimulates further stomach secretions.
  3. Distension also stimulates local (enteric) reflexes that amplify stomach secretions.
  4. Gastrin travels via blood back to stomach and with histamine (paracrine) stimulates secretion.
27
Q

Outline the intestinal phase of digestion (long, hours).

A 
Enterogastric reflex:
Chyme in duodenum:
i) with pH <2
OR
ii) containing lipids
28
Q

The enterogastric reflex inhibits gastric secretions by three mechanisms. These are?

A
  1. Vagal sensory input to medulla from duodenum -> stops secretion of pepsin and HCL.
  2. Local reflexes inhibit gastric secretion.
  3. Secretin and cholecytokinin produced by duodenum decrease gastric secretion in stomach.
29
Q

Absorption of nutrients by stomach.

A

Generally very little.

  • water.
  • electrolytes.
  • some drugs (especially aspirin) and alcohol.
  • fat content in the stomach slows the passage of alcohol to the intestine, (where absorption is more rapid).
30
Q

Role of paneth cell in small intestine.

A

Secretes lysozyme and is capable of phagocytosis.

31
Q

Role of enteroendocrine cell in small intestine.

A

Secretes secretin, cholecystokinin or glucose-dependent insulinotropic peptide.

32
Q

What cells are in the small intestine (4)?

A
  • microvilli.
  • goblet cells.
  • enteroendocrine cell.
  • paneth cell.
33
Q

Secretions in the small intestine (3).

A
  • intestinal juice (success entericus).
  • duodenal (brunner’s) glands in submucosa.
  • digestive (brush border) enzymes.
34
Q

Role of intestinal juice in small intestine.

A

Empty into tubular glands (crypts) of lieberkuhn:

  • water.
  • electrolytes.
  • mucus.

Dilution and lubrication.

35
Q

Role of duodenal (brunner’s) gland in submucosa of small intestine.

A

Alkaline mucus to neutralise acidic chyme from stomach.

36
Q

Digestive (brush border) enzymes and their role in the small intestine.

A
  • disaccharidases: break down disaccharides to monosaccharides.
  • peptidases: hydrolyse peptide bonds.
  • nucleotidases: hydrolyse nucleotides to pentose sugar, phosphate, nitrogenous bases.
37
Q

How is intestinal secretion and motility regulated?

A
  • enteric (local) reflexes: respond to presence of chyme.
  • segmentation depends on distension which sends impulses to the enteric plexus and CNS.
  • parasympathetic impulses increase motility.
  • sympathetic impulses decrease motility.
38
Q

Role of enteric (local) reflexes on intestinal secretion and motility.

A

Respond to the presence of chyme:

  • increase intestinal motility.
  • enterogastrones.

-vasoactive intestinal peptide.

39
Q

Role of vasoactive intestinal peptide?

A
  • stimulates the production of intestinal juice.
  • dilates intestinal capillaries.
  • relaxes SI smooth muscle.
40
Q

Pancreatic secretions have two portions. What are they?

A
  1. Aqueous portion.

2. Enzymatic portion from acini.

41
Q

Aqueous portion of pancreas.

A
  • columnar epithelium lining smaller ducts.
  • water.
  • Na+, K+, HCO3-, pH 8.
  • bicarbonate.
  • secretin stimulates.
42
Q

What does bicarbonate in the aqueous portion of the pancreas do?

A
  • raises duodenal pH.
  • inhibiting pepsin.
  • proper pH for pancreatic enzymes.
43
Q

What does the enzymatic portion from acini cells in the pancreas secrete?

A
  • pancreatic amylase (starch).
  • pancreatic lipases (lipids).
  • trypsinogen (protein).
  • chymotrypsinogen (protein).
  • procarboxypeptidase (protein).
  • deoxyribonucleases (DNA).
  • ribonucleases (RNA).
  • trypsin inhibitor.
  • CCK stimulates.
44
Q

Control of pancreatic secretion.

A
  • vagus nerves: secretion of enzymes.
  • secretin: acidity in duodenum causes increased NaHCO3 release.
  • CCK: fats and proteins -> increased digestive enzyme release.
  • glucose-dependent insulinotropic peotide (GIP).
45
Q

Liver products.

A

Bike salts, bilirubin, cholesterol, fats, fat-soluble hormones, lecithin.

46
Q

What do bile salts do?

A

Emulsify fats (most reabsorbed in the ileum).

47
Q

What affect does secretin have on bike?

A

Stimulates bile secretions.

-increases water and bicarbonate ion content of bile.

48
Q

Carbohydrate metabolism in liver.

A
  • gluconeogenesis (protein and glycerol to glucose).
  • glycogenesis (stored as glycogen).
  • glycogenolysis (glycogen back to glucose).
49
Q

Lipid metabolism in liver.

A
  • synthesis of cholesterol.
  • synthesis of lipoproteins.
  • stores some triglycerides.
  • breaks down some fatty acids -> ATP.
50
Q

Protein metabolism in liver.

A
  • deamination.
  • converts toxic ammonia to urea.
  • synthesises plasma proteins.
  • converts one amino acid into another (transaminations).
51
Q

What is deamination.

A

Removes amine group from amino acids for gluconeogenisis.

52
Q

Other liver functions.

A
  • detoxifies the blood.
  • removes waste products.
  • releases bile salts, to help digestion by emulsification.
  • stores fat soluble vitamins: A, D, E, K.
  • stores iron and copper.
  • kupffer cells phagocytose.
  • activates vitamin D.
53
Q

Chemical digestion in large intestine.

A

NO enzymes, only mucus.
Bacteria:
-ferment undigested CHOs.
-convert undigested proteins into simpler substances.
-turn bilirubin into simpler substances.
-produce vitamins K and B7 (biotin) in colon.

54
Q

What causes the gallbladder to contract and release bile into the duodenum?

A

Vagus nerve.

55
Q

What is a micelle?

A

Bike salts which surround a fatty acid.

ISAP (13 decks)

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