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Physiology > Exam 4 - Digestive System 4 > Flashcards

Exam 4 - Digestive System 4 Flashcards

1
Q

Where does nearly all chemical digestion and nutrient absorption occur?

A

in small intestine

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2
Q

Small intestine must have…

A
  • large surface area exposed to chyme
    It is the longest part of digestive tract

“small” refers to diameter not length

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3
Q

Location of small intestine

A

retroperitoneal along w/ pancreas (posterior to stomach)

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4
Q

Jejunum

A
  • found primarily in “umbilical region”

- MOST DIGESTION AND NUTRIENT ABSORPTION OCCURS HERE

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5
Q

Ileum

A

Has PEYER’S PATCHES - clusters of lymphatic nodules

  • ends at ileocecal junction w/ large intestine
  • HAS SPHINCTER KNOWN AS THE ILEOCECAL VALVE THAT REGULATES THE PASSAGE OF FOOD RESIDUE INTO THE LARGE INTESTINE (division from small intestine and large intestine)
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6
Q

What doe the jejunum and ileum have in common?

A

they are both intraperitoneal - are covered w/ serosa

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7
Q

Circular folds

A

involve only mucosa and submucosa (SLOWS CHYME AND PROMOTES MIXING AND ABSORPTION)

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8
Q

Villi

A
  • most nutrients absorbed by blood CAPILLARY

- most fat absorbed by LACTEAL

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9
Q

Microvilli

A
  • is the “brush border” on cells

- BRUSH BORDER ENZYMES USED FOR FINAL STAGES OF DIGESTION

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10
Q

Crypts

A

pores opening between villi (inverse villi that go into the mucosa)

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11
Q

What are crypts comprised of?

A 
Goblet cells (secrete mucus)
Paneth cells (provide antibacterial secretions such as lysozyme, phospholipase, and defensins)
Absorptive cells

cover it
destroy the bad stuff
absorb what’s left

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12
Q

Submucosa

A

(underneath the muscularis layer)

BRUNNER’S (duodenal) GLANDS in submucosa SECRETE BICARBONATE MUCUS

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13
Q

Peyer Patches

A

populations of lymphocytes to fight pathogens (not absorptive since it’s in the submucosa)

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14
Q

Segmentation

A

purpose is to MIX AND CHURN, not to move material along

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15
Q

Peristalsis

A

gradual MOVEMENT of contents towards colon

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16
Q

Chemical digestion of carbohydrates summary (what we’ve done so far)

A

mouth - salivary amylase
esophagus and stomach - N/A (pH is too low_
duodenum - pancreatic amylase

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17
Q

What acts on DISACCHARIDES to make them monosaccharides?

A

brush border enzymes:
Maltase
Lactase
Sucrase

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18
Q

Lactose intolerance

A

exists when lactase is ABSENT and bacteria ferment undigested sugar; leads to excessive intestinal gas and diarrhea

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19
Q

What should you tell someone who has had a diarrhea episode?

A

Tell them to avoid dairy until the gut has healed itself; BRAT diet, bananas, rice, apple sauce, toast

20
Q

What is in cotransport w/ Na?

A

SODIUM-GLUCOSE TRANSPORT PROTEINS (SGLT) in membrane help absorb GLUCOSE and GALACTOSE

21
Q

How is FRUCTOSE absorbed?

A

by FACILITATED DIFFUSION then converted to glucose inside the cell

22
Q

Digestion of proteins in the stomach

A
  • HCl denatures or unfolds proteins

- pepsin turns proteins into peptides

23
Q

Digestion of proteins in the small intestine

A

Trypsin and Chymotrypsin “take over” protein digestion by breaking polypeptides into OLIGOPEPTIDES (small chunks)

24
Q

What breaks down oligopeptides one amino acid at a time?

A

Carboxypeptidase
Aminopeptidase
Dipeptidase

25
Q

from pancreas; removes amino acids from -COOH end

A

Carboxypeptidase

26
Q

from brush border; removes amino acids from -NH2 end

A

Aminopeptidase

27
Q

from brush border; splits dipeptides in middle

A

Dipeptidase

28
Q

Absorption of proteins

A

amino acid cotransporters (active transport w/ Na or H ions / symporters) move into epithelial cells and facilitated diffusion moves amino acids out into blood stream

29
Q

How do infants absorb proteins?

A

by pinocytosis; which allows for absorption of protective maternal IgA (allows for passive immunity)

30
Q

Why do lipids have more complex digestion and absorption?

A

because they’re hydrophobic

31
Q

What increase surface area of exposure for lipases?

A

Lecithin and bile salts (emulsification droplets)

32
Q

Types of lipases

A
  • lingual lipase activated by stomach acid

- pancreatic lipase

33
Q

Fat hydrolysis

A

emulsification droplets acted upon by pancreatic lipase, which hydrolyzes the 1st and 3rd fatty acids from triglycerides, usually leaving the middle fatty acid

34
Q

role of Micelles

A

micelles in the bile pass to the small intestine and pick up several types of dietary and semidigested lipids

35
Q

Important note about micelles

A

micelles start in the bile as ONLY collection of bile acids; they ACQUIRE the lipid core later as they travel down the intestine

36
Q

What are micelles?

A

minute droplets of bile that wrap above products

37
Q

first step of lipid absorption

A

lipids move to surface of intestinal absorptive cells where they leave the micelles and diffuse into cells

38
Q

Chylomicron

A

within the intestinal cells triglycerides are reformed and covered w/ cholesterol “coat” and protein; chylomicron is moved into secretory vesicles and released into core of villus

39
Q

What takes up chylomicrons?

A

chylomicrons are generally too big to enter capillaries so they are taken up by LYMPHATIC LACTEAL

40
Q

Where do chylomicrons travel from lacteal?

A

they travel in lymph system through CISTERNA CHYLI and THORACIC DUCT into LEFT SUBCLAVIAN VEIN

41
Q

Percentage of cholesterol in our bodies

A

15% - ingested

85% - manufactured in LIVER and INTESTINAL MUCOSA

42
Q

Extremely low density; enter lymph

A

Chylomicrons

43
Q

FORM IN WHICH LIPIDS LEAVE THE LIVER; converted to LDL

A

VLDL

44
Q

Where do triglycerides removed from VLDL go to?

A

stored in adipose cells

45
Q

TRANPORTS CHOLESTEROL TO CELLS

A

LDL; cells have LDL receptors; # of LDL receptors become less once cell’s lipid/cholesterol needs are met (if you have excess it will deposit in other areas of the body)

46
Q

TRANSPORTS EXCESS CHOLESTEROL FROM CELLS TO LIVER

A

HDL; gets ride of cholesterol in the body, allows for excretion

Physiology (13 decks)

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