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Anatomy and Physiology > Exam 2: Digestive System Part 2 > Flashcards

Exam 2: Digestive System Part 2 Flashcards

1
Q

mastication

A

chewing of food
functions:
1. mixes food with saliva
2. reduces size which facilitates swallowing (mechanical digestion)
3. mixes ingested carbs with salivary amylase to begin chemical digestion

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2
Q

catabolism

A

digestion of food

types: physical and chemical

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3
Q

saliva

A

produced by salivary glands

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4
Q

three major salivary glands

A

parotid, submaxillary, sublingual

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5
Q

acinar vs ductal cells in saliva

A

acinar cells- initial saliva (isotonic)
ductal cells- modifies the initial saliva to produce the final saliva by altering conc. of electrolytes (hypotonic - water impermeable)

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6
Q

a-amylase

A

secreted by acinar cells

- begins initial digestion of carbohydrates

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7
Q

lingual lipase

A

secreted by acinar cells

- begins initial digestion of lipids

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8
Q

ductal cells absorption and secretion

A

absorption of Na and CL causes conc. of those in saliva to become lower than their conc. in plasma
secretion of K and HCO3 causes conc. of those in saliva to become higher than those in plasma

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9
Q

three phases of swallowing

A
  1. oral
  2. pharyngeal
  3. esophageal
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10
Q

oral phase of swallowing

A

voluntary

- initiated when tongue forces a bolus of food back toward the pharynx

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11
Q

pharyngeal phase of swallowing

A

involuntary

- propel the food bolus from the mouth through the pharynx to the esophagus

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12
Q

esophageal phase of swallowing

A

involuntary

  • controlled by the swallowing reflex and the enteric nervous system
  • peristalsis drives food downwards and relaxation of the lower esophageal sphincter admits it into the stomach
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13
Q

mucosa cells in the stomach

A 
mucous cells
mucous neck cells
parietal cells
chief cells
enteroendocrine cells
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14
Q

what does enlargement of stomach mucosa show

A

shows gastric pits and glands

- those secrete gastric fluids

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15
Q

parietal cells in stomach mucosa

A

synthesizes and secretes gastric acid to maintain an acidic environment

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16
Q

canaliculi in parietal cells

A

present on surface of lumen

- play a role in secreting gastric acid

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17
Q

intrinsic factor in parietal cells

A

produced by parietal cells

- absorb B12

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18
Q

HCL formation by parietal cells

A

is stimulated by ACh, gastrin, histamine

- HCL acidifies gastric contents between a ph of 1-2

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19
Q

chief cells in stomach mucosa produce:

A
  1. pepsinogen- inactivated protease for protein chemical digestion
  2. lipase- aid in lipid digestion
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20
Q

what does pepsinogen do when gastric pH is low

A

pepsinogen is converted to its active form, pepsin

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21
Q

mucus and mucus neck cells in stomach mucosa

A

produce protective mucus to protect epithelium of the stomach

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22
Q

enteroendocrine cells in stomach mucosa

A 
located in gastric glands, cells produce hormones 
types:
1. enterochromaffin (EC) cells
2. enterochromaffin-like (ECL) cells
3. delta cells
4. G cells
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23
Q

enterochromaffin (EC) cell in the stomach (enteroendocrine cell)

A

produce serotonin

- causes contraction of stomach muscle

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24
Q

enterochromaffin-like (ECL) cell in the stomach (enteroendocrine cell)

A

produce histamine

- activates parietal cells to release HCL and increase acid levels

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25
Q

delta cell in the stomach (enteroendocrine cell)

A

produce somatostatin

- inhibits gastric secretin (blocks parietal cells)

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26
Q

G cells in the stomach (enteroendocrine cell)

A

produce gastrin

- increase parietal cell HCL secretion

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27
Q

gastrin

A

hormone produced by the stomach to produce gastric acid which is secreted by parietal cells

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28
Q

regulations of HCL

A

atropine, cimetidine, omeprazole

- all used to block and stop the process of HCL production

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29
Q

HCL in the stomach

A

helps body break down, digest, and absorb nutrients such as protein.

  • eliminates bacteria and viruses in the stomach
  • protects body from infection
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30
Q

phases of regulation secretions

A
  1. cephalic phase
  2. gastric phase
  3. intestinal phase
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31
Q

cephalic phase

A
  • reflex that stimulates the PNS to release acetylcholine
  • vagus N stimulates gastric secretion before food is swallowed
  • roughly 30% of HCL is secreted in response to a meal
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32
Q

gastric phase

A

food stretches stomach and myenteric and vagovagal reflexes are activated

  • gastic secretion is stimulated, 60% of total HCL is produced
  • histamine and gastrin also stimulate acid and enzyme sectretion
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33
Q

intestinal phase

A

INHIBITION of gastric secretion by CCK, secretin, and reflexes when intestine encounters acid and chyme

  • acid production is slowed wayyyy down, do not want to much acid in the SI
  • breakdown of food is slowed so all nutrients can be absorbed
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34
Q

three phases of gastric motility

A
  1. relaxation of stomach to receive food from the esophagus
  2. contractions that reduce size of food and mix it with gastric secretions to start digestion
  3. gastric emptying that propels chyme into the small intestine
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35
Q

chyme

A

highly acidic material that results from your digestive juices chemically breaking down food.

  • product of mechanical chemical digestion
  • prerequisite for the process of nutrient absorption
  • slows from stomach to small intestine
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36
Q

PNS in digestion

A

hormones gastrin and moltilin INCREASE action potential frequency and force gastric contractions

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37
Q

SNS in digestion

A

hormones secretin and GIP DECREASE action potential frequency and the force of contractions

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38
Q

PNS and SNS digestive hormones

A

PNS- gastrin and motilin, increase contractions

SNS- secretin and GIP, decrease contractions

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39
Q

3 gastric contractions

A
  1. propulsion- peristaltic waves
  2. grinding- vigorous peristalsis and mixing by the pylorus, valve is open slightly
  3. retropulsion- pyloric valve closes, squishes contents back up into stomach
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40
Q

pyloric end of stomach

A

acts as a pump that delivers small amounts of chyme to the duodenum

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41
Q

factors that slow/inhibit gastric emptying

A
  1. presence of fat
  2. presence of H+ ions (low pH) in the duodenum
    - if pH is to low, SI STOPS
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42
Q

tissue types in the pancreas

A
  1. exocrine tissue

2. endocrine cells

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43
Q

pancreatic islet a cells

A

glucagon producing cells

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44
Q

glucagon function (catabolic)

A

INCREASES blood sugar

- pulls sugar out of the cells

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45
Q

pancreatic islet B cells

A

insulin-producing cells

46
Q

insulin function (anabolic)

A

DECREASES blood sugar

- sugar is draw into the cells

47
Q

example of homeostatic imbalance in the pancreas

A

diabetes

  • blood sugar is too high due to lack of insulin production (type 1)
  • or improper response to insulin, acquired (type 2)
48
Q

endocrine cells in the pancreas

A

hormones that are produced by a and b cells in pancreatic islets

  • important for glucose homeostasis
  • islets of langerhans (islands of cells that go onto the bloodstream to indicate digestion is occurring)
49
Q

exocrine tissues in the pancreas

A

produce alkaline fluid with digestive enzymes in the SI for food digestion
-alkaline counters acidity levels

50
Q

acinar cells in the exocrine pancreas

A

found in the acinus

- secrete the enzymatic portion of the pancreatic secretion

51
Q

ductal cells in the exocrine pancreas

A

lined on ducts of the pancreas

  • centroacinar and ductal cells secrete aqueous HCO3- containing components of the pancreatic secretion
  • make area more alkaline
52
Q

two functions of pancreatic secretion

A
  1. aqueous secretion- HCO3- is stimulated by H+ in the duodenum
  2. enzymatic secretion- stimulated by digestion products
    - digests small peptides, amino acids, fatty acids, carbs into absorbable molecules
53
Q

why are pancreatic enzymes to important

A

these enzymes are required for digestion

54
Q

pancreatic enyzmes:

A
  1. amylase- active enzyme
  2. lipase- active enzyme
  3. protease- secreted in inactive forms but then converted to active form in duodenum
55
Q

pancreatic proteases conversion

A

trypsinogen to trypsin in the duodenum

56
Q

pancreatic acinar cell have receptors for

A

CCK and ACh

57
Q

what stimulates CCK secretion

A

I cells from the presence of amino acids, peptides, and fatty acids in the intestinal lumen

58
Q

PNS stimulates:

A

enzyme secretion and increases the action of CCK

59
Q

pancreatic ductal cell have receptors for

A

CCK, ACh, and secretin

60
Q

secretin

A

secreted by S cells of the duodenum in response to H+ in the lumen

  • major stimulant fo aqueous HCO3- rich secretion
  • secretin increases action of CCK and ACh
61
Q

what does secretin signal

A

signals the arrival of acidic chyme from the stomach into the small intestines

62
Q

Bile

A

necessary for digestion and absorption of lipids in the SI

  • stored in the gallbladder
  • produced in the liver
  • secreted continuously by hepatocytes
63
Q

functions of bile

A
  1. absorption- mixture of bile and lipids creates a hydrophobic solution allowing for absorption
  2. bile emulsifiers lipids to prepare them for digestion and then puts lipid digestion into micelle packets for absorption
    - bile surrounds fats/lipids to make them smaller and break them down
64
Q

bile salts

A

conserved and recycled through entero-hepatic circulation

65
Q

bile acids

A

cholesterol is converted into bile acids (bile acids are amphipathic which allows for two functions to occur)

  1. emulsification of lipid clusters
  2. transport of lipids in an aqueous environment
66
Q

bile acids are important for

A

transport and absorption of fat-soluble vitamins

- bile acids are lipid carries

67
Q

micelles in bile acid `

A

when bile acids solubilize many lipids, micelles are created
- fat center, hydrophobic side touching center, hydrophilic side phasing the outside creating emulsified droplets

68
Q

what happens when chyme enters the small intestine

A

acids, partically digested fats, and proteins stimulate the secretion off CCK and secretin

69
Q

cholecystokinin

A

a hormone that is secreted by cells in the duodenum

  • stimulates the release of bile into the intestine
  • secretion of enzymes by the pancreas
70
Q

secretin

A

stimulates biliary duct cells to secrete bicarbonate and water
- this expands the bile and increases the flow into the intestine

71
Q

biliary duct cells

A

secrete bicarbonate (HCO3-) and water which expand volume of bile and increases the flow

72
Q

gallstones

A

composed of insoluble cholesterol

- too much cholesterol

73
Q

liver

A

processes, filters, and manages material in the blood

  • lobules comprised of hepatocytes (liver cells) that process the blood
  • VERY permeable for blood processing
74
Q

portal triad of the liver

A
  1. hepatic portal vein
  2. hepatic arteriole
  3. hepatic duct (bile)
75
Q

function of hepatocytes in the liver

A
  • line cytosiods
  • process absorbs substances
  • synthesize and secrete bile acids
  • bilirubin production and excretion
  • metabolism and storage of key nutrients
  • excrete and detoxify waste
76
Q

3 metabolic functions of the liver

A
  1. carbohydrate metabolism
  2. protein metabolism
  3. lipid metabolism
77
Q

carbohydrate metabolism

A

stores glucose as glycogen (gluconeogenesis)

releases stores glucose into bloodstream

78
Q

protein metabolism

A

synthesizes and modifys amino acids

- converts amonia to urea which is excreted into the urine

79
Q

lipid metabolism

A

fatty acid oxidation

synthesizes lipoproteins, cholesterol, and phsopholipids

80
Q

liver detoxification

A

protects body from toxic substances that are absorbed in the GI tract
“first pass metabolism”
- phases modify the harmful substances by adding a salt to make it soluble so it can be excreted

81
Q

phase 1 reaction of detoxification

A

P-450 enzymes modfy compounds

82
Q

phase 2 reaction of detoxification

A

conjugate the substances

- make them soluble for excretion in bile of urine

83
Q

hepatitis

A

inflammation of the liver

- over time scar tissue forms and destroys hepatocytes

84
Q

cirrhosis in the liver

A

connective tissue regenerates faster than damaged hepatocytes

  • leads to dimished liver activity
  • transplant is required
85
Q

hepatopancreatic ampulla

A

where the bile duct and pancreatic duct join

  • provide digestive components
  • empty into the duodenum
  • these allow the duodenum to do its job
86
Q

GI enzymes

A

carbs, proteins, lipids

87
Q

small intestine mucosa

A

water and nutrient absorption

  1. duodenum- recieves secretion from pancreas and liver from the pancreatic and common bile ducts (get acid out)
  2. jejunum
  3. illeum- large end that emties into the large intestine
88
Q

intestinal mucosa

A

villi are longest inn the duodenum (most absorption occurs here) and shortest in the ileum

  • villi are covered with enterocytes bound by mucus-secreting cells (goblet cells)
  • villi and microvilli increase SA of the small intestine creating a large absorptive surface
89
Q

goblet cells

A

in the mucosa bound to enterocytes

- mucus secreting cells that help move food through the intestines

90
Q

five SI mucosal cell types

A
  1. enterocytes (absorb)
  2. goblet cells (mucus)
  3. enteroendocrine cells
  4. panth cells (defense)
  5. stem cells
91
Q

types of enteroendocrine cells

A

I cells- produce CCK

S cells- produce secretin

92
Q

duodenal glands

A
  • located in duodenum submucosa

- produce alkaline mucus to neutralize acidic chyme from stomach

93
Q

alkaline mucus

A

neutralize acidic chyme from stomach that has entered the SI

94
Q

peyer’s patch

A

aggregated lymphoid follicales that are found in the SI walls

  • help protect against bacterial breaches
  • increase in amount farther down you go in the body
  • most prevalent in the iluem
95
Q

small intestine motility

A

peristalsis- faciltate propulsion between meals
segmentation- mix and breakdown in response to meals. NOT about progression, just mixing
- increases contact with absorptive cells

96
Q

SI digestion

A

microvilli enzymes complete digestion

  • not secreted, always present
  • perform final hydrolysis to break down food to monomers
97
Q

SI secretion

A

crypts secrete fluid and electrolytes

- creates a watery environment for mixing and absorbing

98
Q

when does water diffuse into the lumen

A

when secretion of NaCl occurs

  • balances osmotic gradient
  • high soluble level draws water in for better movement
99
Q

SI absorption

A

transcellular route- across the plasma membrane

paracellular route- across tight junctions between cells

100
Q

absorption routes

A

small molecules are transported by both the transcellular and paracelluar route but tight junctions are impermeable to large molecules
- large molecules are ONLY transported through the transcellular route where transport molecules are present

101
Q

carbohydrate absorption in SI

A 
transporter proteins (symports) form a secondary active transport for monosaccharides 
ex. glucose
102
Q

protein absorption in SI

A

transporter proteins (symports) form a secondary active transport for monosaccharides

  • same as carbs
  • Na is secreted tp facilitate water movement
103
Q

lipids absorption in SI

A

different than carbs and protein

  • fats are breakdown products from lipids and are absorbed into micelles
  • lipids repackaged into chylomicrons (protein covered lipids)
  • secreted into ECF and taken into lymph
104
Q

large intestine anatomy

A
  1. cecum
  2. appendix
  3. colon
  4. rectum
  5. anal canal
105
Q

large intestine function

A

last portion of the alimentary canal and terminal digestion

  • recovery of water and electrolytes from ingesta
  • formation of storage of feces
  • microbial fermentation
106
Q

movement of salt…

A

moves water!

107
Q

large intestine motility

A

haustral contractions - slow segmentation
mass movements- POWERFUL peristalsis
- LI is more for mixing, not breaking down

108
Q

gastrocolic reflex

A

stimulated by foo din stomach

- triggers a mass movement in the LI

109
Q

large intestine secretions

A
  1. mucus- provides protection
    - parasympathetic stimulation increases rate of goblet cell secretion
  2. pumps - exchange of ions
110
Q

pumps in LI secretion

A
  • exchange of bicarbonate ions for chloride ions

- sodium ions for hydrogen ions

111
Q

defecation reflex

A

occurs when feces enter the rectum (mass movement)

112
Q

anal canal sphincters

A
  1. external anal canal - skeletal muscle
    - volunatry, you control it
  2. internal anal canal- smooth muscle
    - involuntary, no control

Anatomy and Physiology (6 decks)

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