Biology *1080 Lecture 16 Flashcards

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1
Q

What is the GI tract?

A

Aids to digest and absorb ingested nutrients, and to excrete waste products of digestion.

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2
Q

What does the GI tract consist of?

A

Oral cavity, esophagus, stomach, small intestine, colon and rectum

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3
Q

What does the GI system do?

A

It “sees” not only our food, but toxic substances and infectious agents

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4
Q

How does the GI tract deal with toxic substances?

A

Vomit and Diarrhea

T-cells localized in the intestinal mucosa

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5
Q

How long is the GI tract?

A

28 ft and folded extensively in the abdominal cavity

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6
Q

Why is the SA large in the GI tract?

A

Due to lots of villi/microvilli (finger-like projections)

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7
Q

What is the variable transit time for ingested meal?

A

30-80 hours

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8
Q

What stays longer in the GI tract?

A

Fibre, where as carbs go quicker through GI tract

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9
Q

What does the GI tract house?

A

Gut microbiome (bacteria) to protect against pathogenic microbes that enter/reside in the tract (breakdown of indigestible food)

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10
Q

What is the GI tract controlled by?

A

Intrinsic nervous system - opening and closing of sphincters

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11
Q

Motility in GI tract

A

Peristalsis (involuntary) - constriction and relaxation of the muscles in the GI tract

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12
Q

Secretion in GI tract

A

Saliva, mucous

Antibodies (protect against antigens)

Digestive enzymes

Bile (breaks down fatty acid)

Bicarbonate (glycerine and three fatty acids)

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13
Q

Digestion in GI tract

A

Break down of food

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14
Q

Absorption in GI tract

A

Water (large intestine)

Nutrients (small intestine)

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15
Q

What is the cephalic phase of digestion and absorption?

A

Secretions initiated by the sight, smell, thought or taste of food (related to the head)

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16
Q

Mechanical digestion

A

Physically breaking down (i.e, chewing)

17
Q

What are the three glands in your mouth?

A

Parotid Gland

Sublingual Gland

Submandibular Gland

18
Q

What is salivary secretion under control by?

A

Autonomic control (stimulated by sympathetic and parasympathetic nervous system)

19
Q

What does salivary secretion do?

A

Softens and Lubricates food

Provides enzymes such as amylase (breaks down carbs/starches) and lipase (lipid break down)

20
Q

What is the influence of the parasympathetic system on digestion?

A

“Rest and digest” - increases intestinal and gland activity, and relaxes sphincter muscles in the GI tract

21
Q

What do parietal cells secrete?

A

Gastric Acid

Intrinsic Factor

22
Q

What stimulates parietal cell secretion?

A

Acetylcholine

23
Q

What do chief cells secrete?

A

Pepsin

Gastric Lipase

24
Q

What stimulates chief cells secretion?

A

Acetylcholine

25
Q

What is the function of secretion from chief cells?

A

Digests proteins and fats

26
Q

What do G cells secrete?

A

Gastrin

27
Q

What stimulates G-cell secretion

A

Acetylcholine

28
Q

What does not get digested in the stomach?

A

Carbohydrates (remember amylase is not found in stomach)

29
Q

What is the main contributor of digestive enzymes?

A

Pancreas

30
Q

What are enzymes related from the pancreas in the form of?

A

Trypsinogen (inactive)

31
Q

Where is trypsinogen activated in?

A

In the small intestine by enterokinase in the brush border of duodenum to form trypsin (protein digestion)

32
Q

What does the Gallbladder store?

A

Bile - fat digestion

33
Q

Where is bile produced from?

A

Liver

34
Q

What are the three main parts of the small intestine in order?

A

Duodenum, jejunum, ileum

35
Q

What is the benefits of small intestine mucosa (villi) ?

A

Villi increase surface area to promote nutrient absorption

36
Q

What are the secretions into the lumen of the small intestine upon the opening of the pyloric sphincter?

A

Bicarbonate

Digestive Enzymes (from pancreas)

Bile Acids (from liver/gal bladder)

37
Q

What are the digestive enzymes anchored on the luminal surface?

A

Disaccharides (carbs)

Amino peptidases (proteins)

38
Q

What happens to people who have celiac disease?

A

The vili in their small intestine become flatten (decrease in SA)

A decreased SA causes a decrease in nutrient absorption resulting in many nutrient deficiencies

39
Q
A