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BIOL *1080 > Lecture 16 > Flashcards

Lecture 16 Flashcards

1
Q

What does GI stand for

A

The GI (Gastro-intestinal) Tract

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2
Q

What are the 6 components of the GI tract and the sphincters/valces between them

A
  1. Oral cavity
    — Upper esophageal sphincter
  2. Esophagus
    —- Lower esophageal sphincter
  3. Stomach
    — Pyloric sphincter
  4. Small intestine
    —- Ileocecal valve
  5. Colon (large intestine)
    — Anal sphincter
  6. Rectum
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3
Q

What is the purpose of muscle Sphincters and valves

A

Muscle Sphincters and valves particularly segregate functions within the tube

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4
Q

What does the GI tract represent

A

Represents a vast body surface area that is exposed to external environment

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5
Q

The GI tract has unique mechanisms to deal with …

A

Can sense or expel noxious substances
– Through vomit or diarrhea

Specialized populations of T cells localized to the intestinal mucosa
– Eg. peyer’s patches

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6
Q

How long is the GI tract

A

About 28 feet long, folded extensively to fit in abdominal cavity

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7
Q

How large is the luminal surface in the human body

A

Large luminal surface of about 200 to 400 square meters due to lots of villi and microvilli

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8
Q

What is the luminal surface

A

Lumin = space within tubes, tracts, cavities and cells in body

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9
Q

How long does it take meals to go through the GI tract

A

Highly variable transit time for ingested meal (total of 30-80 hours)

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10
Q

What does the gut contain

A

microbiome (bacteria, ext)

–protects against pathogenic microbes that enter/reside in tract

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11
Q

What coordinates the opening and closing of sphincters

A

Intrinsic (AKA enteric) nervous system

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12
Q

What are the 4 processes of the GI tract

A
  1. Mobility
  2. Secretion
  3. Digestion
  4. Absorption
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13
Q

What does the GI tract move

A

Ability of organisms and fluid to move and get around

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14
Q

What does the GI tract secrete

A

Saliva
Antibodies
Digestive enzymes

Bile
Bicarbonate

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15
Q

What does the GI tract absorb

A

Water nutrients

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16
Q

What is the first phase of the GI tract

A

The Cephalic Phase of Digestion and Absorption

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17
Q

What is involved in the Cephalic Phase of Digestion and Absorption

A

Chewing and mechanical absorption

18
Q

Where does the the Cephalic Phase of Digestion and Absorption begin

A

In the mouth

19
Q

What is masticiation

A

Chewing

20
Q

What controls salivary secretions

A

Salivary secretion is under autonomic control (stimulated by sympathetic and parasympathetic nervous system)

21
Q

What is the purpose of salivary secretions

A

Softens and lubricates food

Provides enzymes: amylase and some lipase (but no protein digestion)

22
Q

What are salivary secretions in response to

A

Sensory stimuli (sight, smell, taste)

23
Q

What does salivary secretion prepare the GI tract for

A

Prepares the GI tract for food processing

24
Q

What is the second phase of the GI tract

A

The Gastric Phase of Digestion and Absorption

25
Q

What occurs in The Gastric Phase of Digestion and Absorption

A

Sensory cells of the gastric mucosa increases intestinal and gland activity and relaxes sphincters in the GI Tract

26
Q

What nervous system influences the gastric phase of digestion and absorption

A

The parasympathetic nervous system (“rest and digest”)

27
Q

What is absorbed in the stomach

A

Protein and fat but not carbs

28
Q

Pepsin: what is the release stimulant and role

A

Release Stimulant: acetylcholine acid
Role: Digestions protein

29
Q

Gastric lipase: what is the release stimulant and role

A

Release Stimulant: acetylcholine acid
Role: Digestions fats

30
Q

What are the 4 things acetlycholine stimulates for release

A
  1. Gastric acid
  2. Pepsin
  3. Gastric lipase
  4. Gastrin
31
Q

Where does lipid digestion start

A

Started with lingo lipase in mouth - breaks down large fats such as triglycerides

32
Q

When are gastric lipases secreted

A

Gastric lipases secreted as fat moves to stomach

33
Q

When do bile salts and pancreatic lipase interact with fats

A

Once in duodenum on SI

34
Q

What is the effect of bile salts on fat

A

Bile salts cote fat droplets and causes globules to disperse, making them hydrophilic

35
Q

What is the effect of pancreatic lipase on fats

A

Pancreatic lipase present hydrolyze triglycerides into smaller components (free fatty acids and monoglycerides)

36
Q

What happens to fatty acids and monoglycerides

A

Free fatty acids and monoglycerides absorbed my SI for further processing

37
Q

What is the main contributor of digestive enzymes

A

Pancrease

38
Q

Are enzymes released from the pancreas in active or inactive form

A

Inactive - activated in select regions

39
Q

What does the gallbladder store

A

Stores bile produced in liver

40
Q

What is the importance of the small intestinal mucosa

A

Filled with villi which increase surface area to promote nutrient absorption

41
Q

What 3 things are secreted into the lumen of the SI upon the opening of the pyloric sphincter

A
  1. Bicarbonate - from cells in the internal epithelium and in pancreatic secretions
  2. Digestive enzymes - from the pancreas
  3. Bile acids - from the liver/gallbladder
42
Q

What 2 digestive enzymes are anchored onto the luminal surface of the SI

A

Disaccharidases
Amino peptidases

BIOL *1080 (19 decks)

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