Digestive System Flashcards

1
Q

what is another name of the digestive tract?

A

gastrointestinal tract

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2
Q

where does the GI tract extend from?

A

oral cavity to anus

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3
Q

what does the GI tract pass through?

A

passes through pharynx, esophagus, stomach and small and large intestines

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4
Q

what are the two surfaces of the GI tract?

A

mucosal - faces the lumen
serosal- faces the blood

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5
Q

what are mesentery?

A

double sheets of peritoneal membrane, continous collection of tissue

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6
Q

what are the functions of the mesentery?

A
  • suspend portions of small and large intestine from the posterior abdominal wall
  • digestive organs connected to it
  • contains blood vessels, nerves, and lymphatic vessels that go
  • stabilizes portions of attached organs
  • prevent intestines from entangling
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7
Q

what epithelial tissue is the oral cavity lined with?

A

stratified squamous epithelium

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8
Q

what does the tongue secrete that aids in digestion?

A

mucins and lingual lipase

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9
Q

what are the three pairs of salivary glands?

A
  1. parotid glands
  2. sublingual glands
  3. submandibular glands
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10
Q

what do parotid salivary glands produce?

A

serous secretion, enzyme salivary amylase

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11
Q

what two categories of foods begin digestion in the oral cavity?

A

starches and lipids

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12
Q

what do sublingual salivary glands produce?

A

mucous secretion that acts as a buffer and lubricant

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13
Q

what do submandibular salivary glands produce?

A

secretes buggers, glycoproteins, and salivary amylase

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14
Q

what salivary gland produces the majority of saliva?

A

submandibular glands

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15
Q

what are the components of saliva?

A

99.4% water, 0.6% electrolytes, buggers, glycoproteins/mucins, antibodies, enzymes, waste products

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16
Q

what are the functions of saliva?

A
  • lubrication
  • dissolving chemicals that stimulate taste buds
  • initiating digestion of complex carbohydrates through salivary amylase
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17
Q

what are the three regions of the pharynx?

A

nasopharynx, oropharynx, laryngopharynx

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18
Q

what is another word for swallowing?

A

deglutition

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19
Q

what are the three phases of swallowing?

A
  1. buccal phase
  2. pharyngeal phase
  3. esophageal phase
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20
Q

what is the buccal phase of swallowing?

A

tongue pushed bolus against soft palate and back of mouth, triggering swallowing reflex

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21
Q

what is the pharyngeal phase of swallowing?

A

breathing is inhibited as the bolus passes through the closed airway

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22
Q

what is the esophageal phase of swallowing?

A

food moves downward into esophagus, propelled by peristaltic waves and aided by gravity

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23
Q

where does the esophagus bring food?

A

to the stomach

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24
Q

where does the esophagus enter the abdominopelvic cavity?

A

esophageal hiatus

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25
Q

what innervates the esophagus?

A

esophageal plexus

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26
Q

what are the 4 histological layers of the esophagus?

A
  1. mucosal
  2. submucosal
  3. muscularis externa
  4. adventitia
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27
Q

what epithelial cell makes up the mucosal layer of the esophagus?

A

non-keratinized stratified squamous

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28
Q

what is found in the submucosal layer of the esophagus?

A

esophageal glands which produce mucous secretions that reduce friction between bolus and esophageal lining

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29
Q

what is the outermost epithelial layer of the esophagus?

A

adventitia

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30
Q

what is narrowing/tightening of the esophagus called?

A

strictures

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31
Q

what are strictures often caused by?

A

stomach acids/ reflux that damages tissue over time; most common gastroesophageal reflux disease (GERD)

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32
Q

what is a common treatment for strictures?

A

balloon dilators

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33
Q

what are the 4 regions of the stomach?

A
  1. cardia
  2. fundus
  3. body
  4. pylorus
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34
Q

what is the function of the cardia?

A

contains mucous glands; secretions coat connection with esophagus protecting it from acids and enzymes

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35
Q

what is the function of the fundus?

A

secretes most of the acids and enzyme for gastric digestion

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36
Q

what is the function of the body?

A

mixer

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37
Q

what is the function of the pylorus?

A

secretes mucus and digestive hormones

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38
Q

what is the function of the mucosal barrier of the stomach?

A

prevents enzymes/acids from digesting stomach itself

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39
Q

what are the components of the mucosal barrier that make it impermeable?

A
  • goblet cells produce coast of alkaline mucus
  • mucus traps a thick coat of bicarbonate rich fluid
  • epithelial cells that are joined by tight junctions
  • gastric glands that have cells impermeable to HCL
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40
Q

how quickly do damaged epithelial cells/mucosal cells turnover?

A

3-7 days

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41
Q

where are gastric glands found?

A

in the fundus and body of the stomach

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42
Q

what are found at the surface of gastric surfaces?

A

gastric pits

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43
Q

what are the two cells of gastric glands that secrete the majority of gastric juice into the stomach?

A

parietal cells and chief cells

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44
Q

what do parietal cells secrete?

A

intrinsic factor and hydrochloric acid

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45
Q

what do chief cells secrete?

A

pepsinogen

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46
Q

what happens to pepsinogen in the gastric lumen?

A

converted to pepsin (active proteloytic enzyme) by HCL

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47
Q

how is HCL secreted from parietal cells?

A
  1. hydrogen ions generated inside parietal cell and carbonic anhydrase converts Co2 and H2o into carbonic acid
  2. Cl- is brought into the parietal cells and bicarbonate ions are ejected into the interstitial fluid by a countertransport mechanism
  3. chloride ions diffuse across the cell and exit through open chloride channels into the lumen of the gastric gland
  4. the hydrogen ions are actively transported into the lumen of the gastric gland
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48
Q

what is the pH of the stomach kept at due to parietal cell excretions?

A

1.5-2 (very acidic)

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49
Q

what are the 4 functions of the acidic environment?

A
  1. kills microorganisms
  2. denatures proteins and inactivates enzymes in food
  3. helps break down plant cell walls and connective meat tissue
  4. activates pepsin
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50
Q

what do mucous neck cells secrete?

A

acid mucus

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51
Q

what do enteroendocrine cells secrete?

A

gastrin, histamine, endorphins, serotonin, cholecystokinin (CCK), and somatostatin

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52
Q

where are pyloric glands?

A

located in the pylorus

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53
Q

what is the function of the pyloric glands?

A

produce mucous secretions

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54
Q

what is commonly found in pyloric glands?

A

enteroendocrine cells

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55
Q

what are the two important enteroendocrine cells?

A

G cells and D cells

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56
Q

what do G cells produce?

A

gastrin

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57
Q

what is the function of gastrin?

A

stimulates secretion of parietal and chief cells

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58
Q

what do D cells produce?

A

somatostatin

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59
Q

what is the function of somatostatin?

A

a hormone that inhibits release of gastrin

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60
Q

what hormone rises before meals to initiate hunger?

A

ghrelin

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61
Q

what is the role of pepsin in the stomach?

A

preliminary digestion of proetins

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62
Q

what does salivary amylase digest?

A

carbohydrates

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63
Q

what is responsible for the digestion of lipids in the stomach?

A

lingual lipase and gastric lipase

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64
Q

what is the makeup of intestinal juice?

A

mainly water but some mucous

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65
Q

why is intestinal juice slightly alkaline?

A

assists in buffering acids, moistens chyme, keeps digestive enzymes and products of digestion in solution

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66
Q

where does chyme arrive in small intestine?

A

duodenum

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67
Q

what moves chyme to jejunum?

A

weak peristaltic contractions

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68
Q

what controls peristaltic contractions?

A

myenteric reflexes and submucosal motor neurons

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69
Q

are peristaltic contractions under CNS control?

A

no

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70
Q

how long does it take for material to pass from duodenum to end of illeum?

A

~5 hours

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71
Q

what two reflexes speed up movement along small intestine?

A

gastroenteric reflex and gastroileal reflex

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72
Q

what does the gastroenteric reflex do?

A

stimulates motility and secretion along the entire small intestine

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73
Q

what does the gastroileal relex do?

A

a long reflex triggered by stomach activity that triggers relaxation of ileocecal valve, allowing materials to pass from small intestine into large intestine

74
Q

what is the function of the duodenum?

A

receives and neutralizes chyme

75
Q

what is the function of the jejunum?

A

nutrient absorption

76
Q

what is the function of the ileum?

A

lymphoid tissue (peyer’s patches), protect SI from bacteria in LI

77
Q

true or false, the small intestine contains villi?

A

true

78
Q

what capillaries are found on the villi of the small intestine?

A

lymphatic capillary = lacteals

79
Q

what do lacteals transport?

A

substances that cannot enter blood such as chylomicrons (protein + lipid mixtures) b/c they are too large

80
Q

what are the three secretions of the duodenum?

A

gastric inhibitory peptide (GIP), cholecystokinin and secretin (CCK), vasointestinal peptide (VIP)

81
Q

what is the function of GIP?

A

inhibit gastric & stimulates pancreas to release insulin

82
Q

what is the function of CCK?

A

release of pancreatic enzymes and buffers, ejection of bile from gallbladder to emulsify fat

83
Q

what is the function of VIP?

A

dilate intestinal capillaries, facilitates absorption

84
Q

what are the folds on the surface of the stomach called?

A

rugae

85
Q

what cells control the rhythmic cycles of activity in the GI tract?

A

pacesetter cells

86
Q

what is peristalsis?

A

consists of waves of muscular contractions that move a bolus along the length of the GI tract

87
Q

what is segmentation?

A

contractions that churn and fragment the bolus, mix with intestinal secretions, no set pattern, does not push

88
Q

how do the circular and longitudinal contract during peristalsis?

A
  • circular muscles contract behind bolus while circular muscles ahead of bolus relax
  • longitudinal muscles ahead of bolus contract, shortening adjacent segments
  • waves of contraction in circular muscles
89
Q

how does segmental contractions work?

A

alternate segments contract and there is little or no net forward movement

90
Q

what are the three regulations of digestive activities?

A

local factors, neural control, hormonal

91
Q

how does hypertension affect the gut?

A

intestinal barrier is compromised, increased permeability, damaged tight junctions

92
Q

what are the 4 regions of the colon?

A

ascending, transverse, descending, sigmoid

93
Q

what are the pouches of the colon that allow it to expand and elongate?

A

haustra

94
Q

what are the three bands of smooth muscle that run along outer surfaces of the colon?

A

taeniae coli

95
Q

what is the function of taeniae coli?

A

contractions help create the bulges known as haustra. Help initiate peristlasis?

96
Q

what are fatty appendices?

A

teardrop shaped sacs of fat on the serosa of the colon

97
Q

does the large intestine have villi?

A

no

98
Q

what type of cell is abundant in the large intestine?

A

mucous cells

99
Q

what is different about digestive intestinal glands compared to small intestine?

A

deeper and dominated by mucous cells

100
Q

does the large intestine secrete digestive enzymes?

A

no

101
Q

how much nutrient absorption occurs in the large intestine?

A

<10%

102
Q

what are the primary functions of the large intestine?

A
  • prepare fecal material for ejection from the body
  • lubricates fecal material
  • some absorption
103
Q

what is reabsorbed in the large intestine?

A
  • water and electrolytes
  • bile salts
104
Q

what is absorbed in the large intestine?

A
  • vitamins produced by bacteria
  • organic wastes
105
Q

what is C. difficile colitis?

A

bacterial infection of the colon

106
Q

what three substances are formed following the breakdown of peptides by bacteria?

A

ammonia, indole and skittle, hydrogen sulfide

107
Q

what are indole and skatole?

A

nitrogen compounds responsible for odor of feces

108
Q

what is hydrogen sulfide?

A

gas that produces rotten egg odor

109
Q

what does bacteria do to bilirubin?

A

converts it to uribilinogens and stercobilinogens

110
Q

how is intestinal gas formed in the large intestine?

A

bacteria feeds on indigestible carbohydrates

111
Q

true or false, an important function of bacteria in the colon is the production of vitamins?

A

true

112
Q

what are three vitamins produced by bacteria in the colon?

A

vitamin k, biotin, vitamin b5

113
Q

what is the function of vitamin K?

A

required by the liver for synthesizing four clotting factors including prothrombin

114
Q

what is the function of biotin?

A

important in glucose metabolism

115
Q

what is the function of vitamin B5?

A

required in manufacture of steroid hormones and some neurotransmitters

116
Q

what is a major cancer found in colon?

A

colorectal cancer

117
Q

what is the exocrine function of the pancreas?

A

production of enzymes

118
Q

what cells secrete enzymes in the pancreas?

A

acinar cells

119
Q

how are secretions of acinar cells controlled?

A

controlled by hormones of the duodenum (secretin and CCK)

120
Q

what are the 4 pancreatic enzymes?

A
  1. pancreatic alpha-amylase
  2. pancreatic lipase
  3. nucleases
  4. proteolytic enzymes
121
Q

what are the two types of proteolytic enzymes?

A

proteases and peptidases

122
Q

what do proteases break down?

A

large protein complexes

123
Q

what do peptidases break down?

A

small peptide into amino acids

124
Q

what system is responsible for the secretion of bile?

A

heptatic bile duct system

125
Q

what is responsible for the production and secretion of bile?

A

the liver

126
Q

where does the liver secrete bile through?

A

bile canaliculi

127
Q

where does the liver secrete bile to?

A

gallbladder

128
Q

what shape is the gallbladder?

A

hollow, pear shaped sac

129
Q

what is the function of the gallbladder?

A

stores and concentrates bile and releases bile into duodenum

130
Q

what is the stimuli for the release of bile into the duodenum?

A

cholecystokinin

131
Q

are dietary lipids water soluble?

A

no

132
Q

what does mechanical processing in the stomach break fat into?

A

large lipid droplets

133
Q

is pancreatic lipase lipid soluble? what are the implications?

A

no, they only act at the surface of lipid droplets

134
Q

what do lipid salts do to large fat droplets?

A

coat them and cause emulsification, breakdown of droplets which increases surface area and create tiny emulsion droplets

135
Q

what segment of the GI tract does Crohn’s disease influence?

A

any part of the GI tract from the mouth to anus. Mainly affects the ileum

136
Q

what segment of the GI tract does ulcerative colitis influence?

A

large intestine and the rectumq

137
Q

what is an abscess?

A

infected fluid collection in a tissue cavity

138
Q

what is bowel obstruction?

A

scarred, thickened and narrowed bowel amy block flow of contents though the lumen

139
Q

what are fissures?

A

tears in the anus lining that cause pan and bleeding

140
Q

what are fistula?

A

abnormal tunnels that form between 2 structures of the body which are caused by inflammation

141
Q

what is a perforated bowel?

A

chronic inflammation that can weaken the intestinal wall and cause a hole to develop

142
Q

what are strictures?

A

narrowing of the intestine caused by chronic inflammation

143
Q

what are ulcers?

A

chronic inflammation that leads to open sores anywhere in the GI tract from mouth to anus

144
Q

what happens when the mucosal barrier is damaged by Crohns or UC?

A

unrestricted flux pathways open up

145
Q

what are three proteins that are used to link adjacent cells together to maintain gut health and barrier integrity?

A

tight junctions
adherens junctions
desmosomes

146
Q

in C and UC, what happens to the tight junction proteins?

A

inflammation impacts the tight junction proteins to increase permeability and compromise the tight junctions. Unrestricted pathway dominates

147
Q

how does IBD impact the skin?

A

leaky gut barriers, ulcers, mouth ulcers, increased skin infections

148
Q

how does IBD impact the pulmonary system?

A

bronchiectasis, bronchitis, bronchiolitis

149
Q

how does IBD impact the renal system?

A
  • terminal ileal involvement decreases the ability of the SI to absorb fat so fat binds calcium so there is less calcium to bind oxalate which is then excreted by kidney
  • diarrhea from IBD flare increases risk or uric acid stones. get dehydration and concentrated urine
150
Q

how does IBD impact bones?

A

vitamin D deficiency, calcium malabsorption, bone loss (osteopenia and osteoporosis), use of steroids increases bone lossq

151
Q

how does IBD impact hemoglobin?

A

anemia from blood loss in stool
anemia from chronic inflammation (hepcidin increase)
anemia from lack of appetite
anemia from deficit in other nutrients (folate/B12)
may get autoimmune hemolytic anemia
thromboembolism

152
Q

how does IBD impact malnutrition?

A

common in those with Crohns. small intestine is where most nutrients are absorbed. the colon is important in water uptake, malnutrition is less common in those with UC

153
Q

what hormones would increase in response to blood loss from ulcerations in the stomach?

A

EPO and ERFE

154
Q

what substances secreted by gastric cells may be compromised?

A

parietal cells - HCL and intrinsic factor
chief cells - pepsinogen
enteroendocrine cells: gastrin/somatostatin/ghrelin
mucus neck cells: mucus and bicarbonate

155
Q

true or false, skeletal muscle cells are elongated and have multiple nuclei?

A

true

156
Q

do skeletal muscles have striations?

A

yes

157
Q

true or false, cardiac muscle tissue has visible striation and single/binucleate central nucleus?

A

true

158
Q

what movement is skeletal muscle responsible for?

A

voluntary

159
Q

what movement is cardiac tissue responsible for?

A

involuntary

160
Q

what is a distinct feature of cardiac muscle tissue?

A

intercalated discs

161
Q

what shape are smooth muscle cells?

A

spindle shaped

162
Q

do smooth muscle cells have single or multiple nuclei?

A

single central nucleus

163
Q

do smooth muscle cells have striations?

A

no

164
Q

what is the comparison between the contraction time and energy cost of smooth muscle compared to skeletal muscle?

A

takes 30 times longer to contract but at less then 1% the energy cost

165
Q

what is different about the type of myosin in smooth muscle?

A

heads along the whole lenth; actin filament radiate from dense bodies and ends overlap a myosin filament midway between the dense bodies

166
Q

true or false, smooth muscle have sarcomeres and t-tubules?

A

false, no sarcomers or T-tubules

167
Q

true of false, smooth muscle have no Z discs and instead have intermediate filaments attached to dense bodies

A

true

168
Q

how does smooth muscle filaments align when they contract?

A

align diagonally so twists when contract

169
Q

what does smooth muscle have instead of troponin?

A

calmodulin

170
Q

true or false, smooth muscle lacks neuromuscular junctions?

A

true

171
Q

what are the bulbous swellings on innervating nerves of smooth muscle called?

A

varicosities

172
Q

what do varicosities release? and where do they release it?

A

neurotransmitters into wide synaptic clefs called diffuse junctions

173
Q

what are the pouch-like infoldings that sequester ECF containing high conc of Ca ions?

A

caveolae

174
Q

where does Ca enter from to start contraction?

A

enters from ECF and from sarcoplasmic reticulum

175
Q

what does Ca bind to?

A

calmodulin

176
Q

what does the calmodulin-Ca complex do?

A

it activates myosin light chain kinase (phosphorylating enzyme)

177
Q

what does the myosin light chain kinase do?

A

it phosphorylates the myosin light chain which can now bind to the actin filament

178
Q

what splits phosphate from myosin light chain?

A

myosin phosphatase

179
Q

what is the key determinant in the time to relaxation?

A

the amount of myosin phosphatatse?

180
Q

how does Ca get back into ECF or SR?

A

actively pumped by a slow-acting Ca pump

181
Q

what are three reasons why smooth muscle contraction is slower?

A
  • greater distance Ca must diffuse from ECF into cell
  • rate at which action potentials are propagated between smooth muscle cells
  • slower rate of cross-bridge formation between actin and myosin