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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
duodenal glands (brunner's glands):
tubular mucous glands enter into intestinal glands
26
jejunum and ileum
- decrease in diameter, thickness as move away from stomach - nutrient absorption (jeju) - Peyer's patches: lymph nodes - ileocecal junction: ileum meet L int.
27
small intestine secretions
- 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
movements in small intestine
- mixing, propulsion over short distance - cecal distention cause local reflex, constrict (prevent backflow and too much chyme enter cecum)
29
liver histology
- 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
liver parts
- hepatic portal cords composed of hepatocytes - hepatic sinusoids: lined w epithelial, Kupffer cells - bile canaliculis: btwn cells w/in cords
31
Liver functions
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
bile secretion and release
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
pancreatic juice
aqueous; made by columnar epithelium; raise pH by HCO3 absorb ions - enterokinase make trypsinogen > trypsin - trypsin make chymotrypsinogen > chymotrypsin - chymotrypsin make procarboxypeptidase > procarboxypeptides
34
bicarbonate ion production in pancreas
- CO2 + H20 = H2CO3 > H + HCO3 ; make ATP w H - Na down conc gradient antiport/repulsion H out
35
bile
made in the liver and stored in the gallbladder - emulsify fat so enzymes can work
36
Control of pancreatic secretion
cholecystokinin and secretin: pancreatic secretions and release HCl
37
cholecystokinin (CCK)
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
secretin
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
secretions of large intestine
- 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
Colon and rectum
- 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
digestion, absorption, transportation
digestion: mechanical and chemical breakdown of food for absorption into circulation absorption/transport: molec out of digestive tract into circulation for distribution
42
carbohydrates hydrolyzed into monosaccharides
-Cotransport = symport (both move in same direction) -Na down conc gradient and pull monosaccharide into cell (facilitated transport )then into capillary
43
transport lipids across intestinal epithelium
-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
chylomicron
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
micelles
temporary compounds formed during the fat digestion and absorption process
46
lipoproteins
protein and fat clusters that transport fats in the blood - VLDL - HDL - LDL
47
VLDL (very low density lipoprotein)
*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
HDL (High Density Lipoprotein)
* 55% lipid, 45% protein -Transports excess cholesterol from cells to liver
49
LDL (low density lipoprotein)
*: 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
LDL into cells
-LDL receptors have pits to grab LDL -Bind to each other and endocytize into cell
51
amino acid transport
-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
effects of aging
*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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