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Z -Biol 151 > Digestive System > Flashcards

Digestive System Flashcards

1
Q

ingestion

A

introduction of food into stomach

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2
Q

mastication

A

chewing
- chem digestion requires large SA so breaking down large particles mechanically facilitates chem digestion

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3
Q

propulsion

A
  • deglutition : swallowing
  • peristalsis : move material thru digestive tract by waves of circulation smooth muscles ahead of bolus then relaxation waves
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4
Q

local: enteric nervous system

A
  • sensory, motor, and interneurons
  • coordinates peristalsis and regulate local reflexes
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5
Q

general nervous regulation

A
  • Coordination with the CNS.
  • May initiate reflexes because of sight, smell, or taste of food.
  • Parasympathetic primarily
  • Sympathetic input inhibits muscle contraction, secretion, and decrease of blood flow to the digestive tract.
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6
Q

saliva

A
  • compound alveolar salivary glands to make saliva
  • lubrications
  • prevent bacteria infections
  • contain salivary amylase
  • form bolus for swallowing
  • parasympathetic input cause salivary production
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7
Q

salivary glands

A
  • parotid: largest, mostly serous
  • submandibular: serous + mucous,
  • sublingual: small, mostly mucous
  • lingual glands: coiled tubular glands on tongue surface
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8
Q

swallowing: 3 phases

A
  • voluntary: bolus of food moved by tongue from oral cavity to pharynx
  • pharyngeal: reflex, controlled by medulla oblongata, soft palate elevate and upper esophageal sphincter relaxes, food pushed into esophagus by pharyngeal sphincters
  • esophageal: reflex, stretching of esophagus cause ENS to initiate peristalsis
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9
Q

chyme

A

ingested food plus stomach secretions

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10
Q

mucus

A

surface, neck mucous cells
- viscous, alkaline
- protect from acidic chyme and enzyme pepsin
- irritation of stomach mucosa cause greater mucous

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11
Q

intrinsic factor

A

parietal cells.
- Binds with vitamin B12 and helps it to be absorbed.
- B12 necessary for DNA synthesis

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12
Q

HCl

A

parietal cells
- kill bacteria
- stop carb digestion by inactivate salivary amylase
- denature protein
- helps convert pepsinogen to pepsin

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13
Q

pepsinogen

A

packaged in zymogen granules released by exocytosis.
pepsin catalyzes breaking of covalent bonds in proteins
- inactive form of pepsinga

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14
Q

HCl production

A
  • CO2 and H2O make H2CO3 (in presence of CA), extra H forced by ATP (dephosph into ADP) into gastric pit (active transport)
    -K leaves as H enters gastric pit (antiport)
  • HCO3 down conc gradient and out of cell, Cl in (antiport/secondary active transport)
  • Cl down into gastric pit
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15
Q

cephalic phase

A
  • taste/smell food, tactile sensation in mouth or thoughts stimulate medulla oblongata
  • vagus (X) cause increase in saliva production
  • gastrin stimulated to make parietal cells (stomach acid)
    (before food in mouth)
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16
Q

gastric phase

A

arrival of food in stomach
- myenteric and vagovagal reflex
- increase gastrin (HCl) and histamine

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17
Q

intestinal phase

A

further breakdown of food, and absorption
- CCK and secretin released
- sympathetic nervous system (inhibition)
- parasympathetic nervous system (stimulatory)

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18
Q

small intestine

A

most digestion and absorption of nutrients and water
- duodenum: first 25cm
- jejunum: 2.5m
- Ileum: 3.5m (Peyer’s patches)

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19
Q

modifications to increase surface area

A

Increase surface area 600 fold
-Plicae circulares (circular folds)
-Villi that contain capillaries and lacteals. Folds of the mucosa
-Microvilli: folds of cell membranes of absorptive cells

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20
Q

absorptive cells

A

w microvilli, produce digestive enzymes and absorb digested food

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21
Q

goblet cells:

A

produce protective mucous

22
Q

endocrine cells:

A

produce regulatory hormones

23
Q

granular (paneth) cells:

A

protect from bacteria

24
Q

intestinal glands (crypts of Lieberkuhn):

A

tubular glands at base of villi

25
Q

duodenal glands (brunner’s glands):

A

tubular mucous glands enter into intestinal glands

26
Q

jejunum and ileum

A
  • decrease in diameter, thickness as move away from stomach
  • nutrient absorption (jeju)
  • Peyer’s patches: lymph nodes
  • ileocecal junction: ileum meet L int.
27
Q

small intestine secretions

A
  • Fluid (water, electrolytes, mucous)
  • mucous (protect from acid and bacteria)
  • Digestive enzymes:
    disaccharidases: breakdown into mono
    peptidases: hydrolyze peptide bond
    nucleases: break down nucleic acids
  • duodenal glands (stimulated by vagus nerve, secretin)
28
Q

movements in small intestine

A
  • mixing, propulsion over short distance
  • cecal distention cause local reflex, constrict (prevent backflow and too much chyme enter cecum)
29
Q

liver histology

A
  • CT branch from porta to interior
  • lobules: portal triad (hepatic portal vein/artery/duct)
  • central veins unite to form hepatic veins enter inf VC
30
Q

liver parts

A
  • hepatic portal cords composed of hepatocytes
  • hepatic sinusoids: lined w epithelial, Kupffer cells
  • bile canaliculis: btwn cells w/in cords
31
Q

Liver functions

A

liver cell: hepatocyte
- bile production
-storage (glycogen, fat, vitamins, Cu, Fe)
- interconversion of nutrients
- detoxification (ammonia > urea)
- phagocytosis (get rid of old WBC and RBC)
- synthesize blood components

32
Q

bile secretion and release

A

gastrin into blood system to release HCl, pepsinogen
- cholecystokinin excitatory to bile
- secretin excite bile production in gallbladder
- bile, pancreatic secretions raise pH (2-4 for pepsin, 6-8 for others)

33
Q

pancreatic juice

A

aqueous; made by columnar epithelium; raise pH by HCO3 absorb ions
- enterokinase make trypsinogen > trypsin
- trypsin make chymotrypsinogen > chymotrypsin
- chymotrypsin make procarboxypeptidase > procarboxypeptides

34
Q

bicarbonate ion production in pancreas

A
  • CO2 + H20 = H2CO3 > H + HCO3 ; make ATP w H
  • Na down conc gradient antiport/repulsion H out
35
Q

bile

A

made in the liver and stored in the gallbladder
- emulsify fat so enzymes can work

36
Q

Control of pancreatic secretion

A

cholecystokinin and secretin: pancreatic secretions and release HCl

37
Q

cholecystokinin (CCK)

A

A hormone secreted by the small intestine (duodenum) in response to the presence of fats.

  • excites: gallbladder to release bile into small intestine
  • inhibit: gastric emptying
38
Q

secretin

A

A hormone secreted by the small intestine (duodenum) in response to low pH

  • excites: pancreatic fluid and HCO3 secretion
  • inhibits: gastric acid secretion of stomach parietal cells
39
Q

secretions of large intestine

A
  • mucous provides protection
  • pumps: bacteria produce acid and exchange HCO3 for Cl, and Na for H (repulsion as same charge)
  • Flatus
  • Vit K to be reabsorbed
  • Feces (water, undigested food, sloughed off epithelial cells, etc)
40
Q

Colon and rectum

A
  • presence of chyme in duodenum stimulate mass mvmnt
    -Cecum is full the ileocecal valve shuts and mass mvmnts in descending colon
    -Peristalsis move material into intestines once ileocecal valve reopens
    -Rectum pressure determines if bowel mvmnt occur (internal sphincter)
    -Peristalsis food into cecum
41
Q

digestion, absorption, transportation

A

digestion: mechanical and chemical breakdown of food for absorption into circulation
absorption/transport: molec out of digestive tract into circulation for distribution

42
Q

carbohydrates hydrolyzed into monosaccharides

A

-Cotransport = symport (both move in same direction)
-Na down conc gradient and pull monosaccharide into cell (facilitated transport )then into capillary

43
Q

transport lipids across intestinal epithelium

A

-Bile salts (emulsify fatty acid) & monoglycerides diffuse into epithelial cell, then form triglyceride (protein coated (chylomicron) and exocytosied) then into capillary then lacteal (lymphatic system)
-Simple diffusion, micelles, chylomicron, lymphatic system move into liver NOT circ syst

44
Q

chylomicron

A

formed in the intestinal epithelium to transport long-chain triglycerides to the tissues
- 90% triglyceride, 5% cholesterol, 4% phospholipid, 1% protein
- enter blood stream and travel to adipose tissue

45
Q

micelles

A

temporary compounds formed during the fat digestion and absorption process

46
Q

lipoproteins

A

protein and fat clusters that transport fats in the blood
- VLDL
- HDL
- LDL

47
Q

VLDL (very low density lipoprotein)

A

*92% lipid, 8% protein
-Form in which lipids leave the liver
-Triglycerides removed from VLDL and stored in adipose cells. VLDL has been converted to LDL.

48
Q

HDL (High Density Lipoprotein)

A
  • 55% lipid, 45% protein
    -Transports excess cholesterol from cells to liver
49
Q

LDL (low density lipoprotein)

A

*: 75% lipid, 25% protein
-Transports cholesterol to cells
-Cells have LDL receptors
-# of LDL receptors become less once cell’s lipid/cholesterol needs are met.

50
Q

LDL into cells

A

-LDL receptors have pits to grab LDL
-Bind to each other and endocytize into cell

51
Q

amino acid transport

A

-Na down conc gradient
-Tri/di peptide or AA into cell via cotransport (symport - move in at same time)
-Tri/di peptides broken into AA in cell , then via active transport into capillary, then to liver
-Much more energetic to absorb protein as need ATP

52
Q

effects of aging

A

*Decrease in mucus layer, connective tissue, muscles and secretions
*Increased susceptibility to infections and toxic agents, increase in incidences of ulcerations and cancers

Z -Biol 151 (9 decks)

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