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Physiology 1021 > Gastrointestinal Physiology > Flashcards

Gastrointestinal Physiology Flashcards

1
Q

What are the 4 processes of the digestive system?

A
  1. secretion
  2. digestion
  3. motility
  4. absorption
    diagram page 297
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2
Q

Anatomy of the digestive tract?

A

diagram page 298

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3
Q

What happens in the mouth?

A
  • mechanical and chemical digestion
  • contains salivary amylase that helps with carb digestion
  • babies contain lingual lipase (only active in the stomach) that help break down fat
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4
Q

Anatomy of the upper gastrointestinal tract?

A

diagram page 299

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5
Q

What are the 3 glands in the mouth?

A
  1. parotid gland- secretes watery liquid containing amylase
  2. submandibular gland- secretes a thicker liquid containing mucus and amylase
  3. sublingual gland- secretes more mucus and less amylase
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6
Q

What are the 3 stages of swallowing?

A
  1. voluntary stage- have control
  2. pharyngeal stage- movement of bolus down esophagus
  3. esophageal- movement of bolus through esophagus
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7
Q

How does food move during swallowing?

A

through mastication in the mouth and peristalsis (controlled by medulla oblongata) in the esophagus

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8
Q

What happens in the stomach?

A
  • bolus is liquified to enhance enzymatic digestion

- 2-3L of gastric juices are secreted into the stomach each day

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9
Q

Anatomy of the stomach?

A

diagram page 301

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10
Q

What are the layers of the stomach?

A

diagram page 302

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11
Q

What are the exocrine cells in the stomach?

A
  • mucus neck cells (secretes mucus)
  • chief cells (secretes pepsinogen and gastric lipase)
  • parietal cells aka oxyntic cells (intrinsic factor, H+ and Cl-)
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12
Q

What is the endocrine cell in the stomach?

A

G cell

-secrete hormone gastrin that is involved with gastric motility and function

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13
Q

What are the mechanical digestion types in the stomach?

A
  • propulsion: gentle mixing waves
  • grinding: vigorous mixing from body to pylorus
  • retropulsion: small amounts of chyme enters into the duodenum (30mins)
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14
Q

What are the chemical digestion types in the stomach?

A
  • gastric lipase: breaks down fats
  • lingual lipase: activated by HCl, lipid digestion in babies
  • salivary amylase: inhibited by HCl
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15
Q

What are the different functions of acid in the stomach?

A
  • activates lingual lipase
  • activates pepsin
  • inactivates salivary amylase
  • kills microbes
  • denatures proteins
  • stimulates secretion of hormones
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16
Q

What does the the ending “ogen” mean?

A

means needed to be activated by something in order to work

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17
Q

What does the duodenum do?

A
  • receives enzymes from the stomach first
  • location of enzymes mixing with chyme
  • most digestion occurs here
  • secretions from the liver/ pancreas
  • can increase/ decrease digestion
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18
Q

What does the jejunum do?

A
  • many villi to increase SA of the tube for optimal absorption
  • most absorption occurs here
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19
Q

What does the Ileum do?

A
  • longest segment
  • less villi
  • can absorb nutrients if necessary
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20
Q

Fun facts of the small intestine

A
  • every carb you ingest will be absorbed
  • 98% of proteins are absorbed
  • 95% of fats are absorbed
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21
Q

What are the layers of the small intestine?

A
  1. Mucosa: contains exocrine and endocrine cells, have villi and crypts (increase SA)
  2. Submucosa: identical to stomach
  3. Muscularis: identical to stomach
  4. Serosa: identical to stomach
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22
Q

What is segmentation?

A
  • occurs only in the intestine

- specialized mixing contractions that mix chyme with digestive juices

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23
Q

What is peristalsis?

A
  • movement of the bolus down the esophagus in one direction

- also occurs in the small intestine

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24
Q

What are the exocrine cell types in the intestinal walls?

A
  • absorptive cells: epithelial cells with microvilli
  • goblet cells: secretes mucus to protect cells from acid in stomach
  • intestinal gland cells: secretes intestinal juice that are slightly alkaline
  • paneth cells: secretes lysozyme that kills microbes and breaks down bacteria
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25
Q

What are the endocrine cell types in the intestinal walls?

A
  • S cells: secretes secretin
  • CCK cells: secretes cholecystokinin to gallbladder to release bile and pancreas to release digestive enzymes
  • K cells: secretes glucose dependent insulinotrophic peptide (GIP) that tells pancreas to release insulin
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26
Q

What are microvilli?

A
  • also called brush border
  • increase the SA of the plasma membrane to increase nutrient reabsorption
  • have brush border enzymes
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27
Q

What are brush border enzymes?

A
  • lactase: breaks down lactose
  • sucrase: breaks down sucrose
  • maltase: breaks down maltose
  • aminopeptidase
  • dipeptidase
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28
Q

What is the summary of the small intestine?

A

page 307

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29
Q

What is the summary of the stomach?

A

page 303

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30
Q

What happens in the large intestine?

A
  • main function is to finish absorption
  • nutrients absorbed here are not the same as in the small intestine
  • terminal section is responsible for the production of vitamins and the formation of feces
31
Q

What is the anatomy of the large intestine?

A

diagram page 308

32
Q

What is the motility of the large intestine?

A
  • gastroileal reflex: presence of food in the stomach stimulates the opening of the ileocecal valve
  • haustral churning: mixing of contents from one haustra to the other, improves the reabsorption of water
  • peristalsis and mass peristalsis: unidirectional
33
Q

What does the pancreas do?

A

-endocrine and exocrine functions

34
Q

What are the cellular structures of the pancreas?

A

diagram page 309

35
Q

What are the functions of the exocrine secretions of the pancreas? (ductal)

A

bicarbonate: neutralizes acid from stomach

36
Q

What are the functions of the exocrine secretions of the pancreas? (Acinar/CCK)

A
  • pancreatic amylase: digestion of carbs
  • pancreatic lipase: digestion of fat
  • trypsinogen-> trypsin: digest protein
  • chymotrypsiogen-> chymotrypsin: digest proteins
  • procarboxypeptidase-> carboxypeptidase: digest proteins
  • prophosphlipase-> phospholipase: digest phospholipids
  • procolipase-> colipase: aids in lipid digestion but is not an enzyme

diagram page 310

37
Q

What are the functions of the endocrine secretions of the pancreas? (Islets of Langerhans)

A
  • Insulin: from beta cells, moves glucose into cells of body
  • glucagon: from alpha cells, releases glucose from cell back into blood
  • somatostatin: from delta cells, helps with digestion and metabolism
38
Q

What does the liver do?

A
  • main cell type is hepatocytes
  • secrete bile (enzyme helper)
  • absorption of lipids
  • sinusoids are blood capillaries that receive blood oxygen from the hepatic artery and the portal vein
  • sinusoids join together to deliver blood in a central vein and then to the hepatic veins
  • unique blood supply
39
Q

What is the flow of blood in the liver?

What is the structure of the liver?

A

diagram page 312

40
Q

What are the functions of the liver?

A
  • synthesis of bile salts: help with lipid digestion
  • excretion of bilirubin: waste product of hemoglobin
  • metabolism of carbs, lipids and proteins
  • processing of drugs and hormones
41
Q

What is bile?

A
  • produced by hepatocytes
  • stored in gallbladder
  • released in to the small intestine
  • aids in digestion of lipids but it is because it helps expose more lipids to the enzymes that digest them
  • bile salts make lipids more soluble a process called emulsification
42
Q

What are the components of bile?

A
  • bile salts
  • cholesterol
  • bile pigments (bilirubin)
  • water and ions
43
Q

What does the gallbladder do?

A
  • stores bile
  • becomes more concentrated in the gallbladder (better at digesting fats)
  • CCK contracts the gallbladder
44
Q

What is the structure of the gallbladder?

A

diagram page 314

45
Q

Describe the Cephalic Phase Regulation?

A
  • controlled by the brain, before you eat
    1. stimulus- sight, smell, see food
    2. Neural control- through medulla oblongata, activation of the submucosal plexus neurons (secretions) and myenteric plexus neutrons (motility)
    3. increased secretions in: salivary glands, stomach, small intestine
    4. increased motility in: stomach, small intestine
46
Q

Describe the Gastric Phase Regulation?

A

controlled by stomach

  • stimulus: presence of bolus causing stomach to stretch
  • Neural control: sensory info to the submucosal plexus and to the myenteric plexus
  • Hormonal control: gastrin
  • both cause increase is secretions from: stomach and intestines
  • increased motility in: stomach, gastric emptying
47
Q

Describe the Intestinal Phase Regulation?

A

controlled by small intestine

  • stimulus: presence of chyme in small intestine
  • Neural control: sensory info to submucosal plexus and myenteric plexus
  • hormonal control: secretin (S cells), CCK, GIP (K cells)
  • increase secretions from: intestine and pancreas
  • pancreas releases bicarbonate from ductal cells, enzymes from acinar cells and insulin from beta cells
  • increased motility of intestine and gall bladder
  • also inhibits gastric phase: decreased HCl secretions and motility of stomach, gastric emptying
48
Q

What are simple carbohydrates?

A
  • monosaccharides: glucose, galactose, fructose

- disaccharides: lactose, sucrose, maltose-> body can’t absorb these

49
Q

What are complex carbohydrates?

A
  • starch (plant storage of glucose)

- glycogen (animal storage of glucose)

50
Q

What is the process of carbohydrate digestion?

A

mouth: salivary amylase converting starch into maltose
stomach: salivary amylase is deactivated
small intestine/ pancreas: pancreatic amylase
diagram page 318

51
Q

What is the process of carbohydrate absorption?

A

diagram page 319

52
Q

What are the sources of proteins?

A
  • animal and plant sources
  • AA, 20 different kinds
    • > essential in diet
    • > nonessential body
  • dipeptides: 2 AA together
  • tripeptides: 3 AA together
  • polypeptides: 4 of more AA
53
Q

What are the processes of protein digestion?

A

stomach: pepsin turning polypeptides into smaller peptides
small intestine: amino peptidase, dipeptidase
pancreas: trypsin, chymotrypsin, carboxypeptidase
diagram page 320

54
Q

What is the process of protein absorption?

A

diagram page 321

55
Q

What are the sources of fat?

A
  • triglycerol= glycerol + 3 fatty acids
  • fatty acids vary in length (4-24 carbons, most common is 18)
  • can be saturated (single bonds) or unsaturated (double bonds, the more you have the more liquidy)
56
Q

What is the process of fat digestion?

A

stomach: lingual and gastric lipase
small intestine: most digestion
pancreas: pancreatic lipase and collipase
liver: bile

57
Q

How do bile salts help in fat absorption?

A

-fat forms big droplets because it doesn’t like water
-bile coats the droplets to keep them small
-intestine shakes the fat droplets and makes them smaller
-colipase moves bile salts apart so that pancreatic lipase can chemically digest the fat
-body can only absorb monoglycerides and free fatty acids
-fat doesn’t dissolve in chyme very well
diagram page 323

58
Q

What is the process of fat absorption?

A

diagram page 324

59
Q

What are the 4 sets of reactions that make up cellular respiration?

A
  1. glycolysis: glucose converted into pyruvate (10 steps), ATP
  2. pyruvate metabolism: pyruvate into Acetyl-CoA
  3. Citric Acid Cycle: acetyl CoA metabolized to form ATP and NADH and FADH2
  4. ETC: FADH2 and NADH converted into more ATP
60
Q

What are the 4 fates of glucose?

A
  1. ATP production
  2. AA synthesis: converted to form AA if needed
  3. glycogen synthesis: storage of glucose
  4. Triglyceride synthesis: when glucose is in excess (lipogenesis)
61
Q

Describe glucose uptake in the cells?

A
  • cells of the body take glucose from your blood in order to use for ATP production
  • glucose uniporters
  • move glucose from high to low concentration
62
Q

What is glycogenesis?

A
  • the storage of glucose
    -some cells like skeletal muscle and liver have a large capacity to store glucose as glycogen
    -some cells like the brain cannot store glucose as glycogen
    diagram page 327
63
Q

What is glycogenolysis?

A
  • breakdown of glycogen
  • glycogen is converted into glucose-6-phosphate to be used for ATp production
    -liver is unique because it can continue to form glucose which then can be released into circulation
    diagram page 327
64
Q

What is gluconeogenesis?

A

-formation of new glucose
-liver can create new glucose form non-carb sources
-from AA you eat, lactic acid, glycerol
diagram page 328

65
Q

What are the fates of lipids?

A
  1. stored in adipose tissue as fat deposits
  2. oxidized to produce ATP-> more ATP than glucose
  3. formation of structural molecules (phospholipids, myelin sheath)
66
Q

How are triglycerides stored in the body?

A
  • 98% of our energy source is from triglycerides

- 50% is stored in the subcutaneous layer of our skin

67
Q

What is the process of lipolysis?

A

breakdown of triglycerides into glycerol and fatty acids

diagram page 329

68
Q

What is lipogenesis?

A

-formation of triglycerides from non-lipid sources
-liver and adipose cells can take triglycerides from glucose and AA
diagram page 329

69
Q

What is ketogenesis?

A
  • ketone bodies are formed by the joining of 2 Acetyl CoAs
  • liver cells can make ketone bodies which diffuse into the blood
  • heart and kidney prefer ketones to produce ATP
  • ketones are acidic
  • disrupts homeostasis
70
Q

What is protein anabolism?

A

-formation of proteins from AA

occurs on ribosomes

71
Q

What are the 4 different types of protein?

A
  1. enzymes
  2. hormones
  3. structural components
  4. transporters
72
Q

What is protein catabolism?

A
  • breaking down of proteins into AA

- hepatocytes can convert AA into fatty acids, ketone bodies or glucose

73
Q

What is the absorptive state?

A

when you eat food

diagram page 331

74
Q

What is the post- absorptive state?

A

When you’re hungry

diagram page 332

Physiology 1021 (9 decks)

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