mastering A&P chapter 24

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digestive system
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1

What is the difference between anabolism and catabolism?

Anabolism uses raw material to synthesize essential compounds and catabolism decomposes substances to provide energy cells need to function.

2

2. What two essential ingredients are required in catabolic reaction?

2. Oxygen and broken down organic molecules

3

What are organic molecules broken down by?

Intracellular enzymes

4

What are two other names for the digestive tract?

Gastrointestinal tract (GI) and alimentary canal

5

What is the distance of the digestive tract? What all does it pass through?

Oral cavity to anus; pharynx, esophagus, stomach, and small and large intestines

6

What are the six functions of the digestive system?

Ingestion, mechanical processing, digestion, secretion, absorption, and excretion

7

What is ingestion? When does it occur?

Bringing food in; when materials enter Digestive tract

8

What is mechanical processing?

The crushing and shearing

9

Where does digestion occur? What is it?

Stomach; chemical breakdown of food for absorption

10

What is secretion? How are thing secreted in the digestive tract?

Release of water, acids, enzymes, buffers, and salts; by epithelium and glandular organs

11

What occurs in absorption?

Organic substances move

12

What occurs in excretion?

Materials are removed

13

What do visceral smooth muscle cells rely on? Why?

Self-communication; lack direct connection with motor neuron

14

How are visceral smooth muscle cells arranged? How are they connected?

Sheets or layers; electronically by gap junction and mechanically by dense bodies

15

What kind of stimulation can visceral smooth muscle cells have? How are some stimulated?

Neural, hormonal, or chemical; pacesetter cells

16

Where are some visceral smooth muscle cells located?

Digestive tract walls, gallbladder, bladder, etc.

17

What does the plasticity of smooth muscle important for?

Allows organs to adapt shape and still contract

18

What is smooth muscle tone?

Normal background activity and tension due to various stimulations

19

What are the two types of movement and regulations of the digestive tract?

Peristalsis and segmentation

20

What is peristalsis?

Wave of muscle contraction that propel bolus through digestive tract

21

What is segmentation? Where does it occur?

Cycles of contraction that churn & fragment bolus; In many areas of small intestine & some of large

22

What is the primary stimulus for digestive activity?

Local factors

23

What are the short reflexes of neurons controlled by?

Myenteric plexus

24

What are long reflexes of neurons controlled by?

Interneurons and motor neurons

25

What are the primary stimulus types for digestive activities?

pH of lumen; physical distortion of DT wall, and presence of chemicals

26

What kinds of hormones control the digestive tract and where are they produced?

Peptides; enteroendocrine cells within epithelium

27

What are mesenteries? What two things do they do?

Double sheet of peritoneal membrane; provides access route for blood vessels, nerves, and lymphatic vessels- also stabilizes position of attached digestive organs

28

What does the peritoneal cavity do?

Encloses stomach and most of the intestines

29

What is the peritoneal cavity lined with? What are the parts of it? What does it secrete and why?

Serous peritoneum; parietal and visceral; peritoneal fluid to lubricate organs

30

What are the two mesenteries that exist during development?

Dorsal and ventral

31

What does the dorsal become?

Greater omentum, mesentery proper, & mesocolon

32

What does the ventral become?

Lesser omentum and falciform ligament

33

Which is more efficient in propelling intestinal content from one place to another: peristalsis or segmentation?

Peristalsis

34

What effect would a drug that blocks parasympathetic stimulation of the digestive tract have on peristalsis?

It would slow it down because the muscle tone would be increased

35

where does the majority of digestion happen?

stomach

36

what materials are found in the stomach? what do they create?

food, saliva, and gastric gland secretions; chyme

37

what are the regions found in the stomach?

fundus, cardia, body, and pylorus

38

where is the fundus found?

superior to esophageal connection

39

what does the cardia do and why?

secrete mucus to protect esophagus from acid/enzymes

40

what is the largest portion of the stomach?

body

41

what leads to the small intestine in the stomach?

pylorus

42

where is the lesser curvature found?

medal surface

43

where is the greater curvature found?

lateral and inferior surfaces

44

what is found in addition to circular and longitudinal layers in muscularis externa?

oblique muscle layer

45

what are rugae and what do they allow?

mucosal wrinkles that flatten when stomach fills; they allow muscles to expand

46

what are the pyloric structures?

pyloric antrum, pyloric canal, and pyloric sphincter

47

what portion of the pylorus is a smooth muscle band that regulates release of chyme into duodenum?

pyloric sphincter

48

what portion of the pylorus is empties into small intestine?

pyloric canal

49

what portion of the pylorus is connected the stomach body?

pyloric antrum

50

what do gastric glands secrete? where do gastic glands open? what do the stem cell at the neck do?

most of the acid and enzymes enabling gastric digestion; to stomach luman through gastric pits; replace cells lost into chyme

51

what do parietal cells secrete? what are these secretions used for?

intrinsic factor- B12 absorption; HCl- activates pepsinogen to keep stomach at pH~2

52

what do chief cells secrete? what does this secretion do?

pesinogen; becomes pepsin when activated

53

what is pepsin?

active proteolytic enzyme

54

what tow things are also secreted in infant? why?

rennin and gastric lipase to aid in digestion of milk

55

what are G cells? what do they produce?

enteroendocrine cells; variety of hormones

56

how is HCl produced?

carbonic anhydrace is sued to create bicarbonate ions and hydrogen ions from CO2 and H2O

57

where is hydrogen released in HCl production? what else is released here?

into gastric gland lumen; chloride

58

what happens to the bicarbonate? what is formed?

transported into blood; alkaline tide

59

what can production of acid and enzymes by the gastric mucosea be controlled/regulated by?

controlled by CNS regulated by short reflexes of ENS and hormones of digestive tract

60

what are the three phases of gastric control?

cephalic, gastric, and intestinal

61

what do many intestinal structures do?

add surface area to increase aborption

62

what are permanent transverse folds found mostly in the jejunum called?

plicae curcularis

63

what are cell membreane extensions on simple columnar cell linings of villi surfaces called?

microvilli

64

what are fingerlike projections on the mucosa called?

intestinal villi

65

what do these three things do together?

add 600 times more area for absorption compared to smooth, flat walls

66

where does 90% of absorption occur? where does the other 10% occur?

small intestine; large intestine

67

what are the three regions of the intestine?

duodenum, jejunum, and IIeum

68

describe the duodenum.

receives chyme from the stomach and digestive secretions from the liver, gallbladder and pancreas; mostly retroperitoneal; few pilcae circulari and small vili; many duodenal glands secreting mucus

69

what I the duodenum's main function?

neutralizes acidic chyme

70

describe and give the location of the jujunum. what happens here?

has numerous pilicae circularis and abundant, long vili; majority of chemical digestion and nutrient absorption

71

why does the IIeum have few pilicae curculare and stumpy vili?

not much absorption occurs here.

72

what does the iieum's submucosa contain? what does the iieum control?

aggregated lymphoid modules; material clow into cecum of large intestine

73

which four of the five major hormones that regulate digestive activities are produced by the duodenum?

gastrin, secretin, gastric inhibitory peptide,and cholecystokinin

74

are equal amounts of the hormones secreted every meal?

no only the amount needed of each is used

75

what is gastrin secreted by? where is this located?

secreted by G cells in the pyloric antrium and enteroendocrine cells of the duodenum

76

what stimulates gastrin particularly? what does it do?

food in the stomach and duodenum with high protein content; increases stomach mobility and production of gastric acids and enzymes

77

when is secretin released from the duodenum? what does it do?

when chyme arrives; increases secretion of bile from liver and buffers from pancreas. also decreases gastric motility and secretory rates. (neutralizes pH also)

78

which hormone is released by the duodenum when fats and carbohydrates enter the small intestine and inhibits gastric activity while increasing insulin release? what are secondary effects of this hormone?

gastric inhibitory peptide (GIP); stimulating duodenal glands, stimulating lipid synthesis in adipose, and increased skeletal muscle use

79

which hormone is released by the duodenum are secrete when chyme arrives especially when it is high in lipids and partially digested proteins? what does this hormone do?

cholecystokinin; increase enzyme production and secretion from pancreas and bile from gallbladder. also inhibits gastric activity and may reduce hunger sensation is CNS

80

regulation of gastric activity image

card image
81

what are thew two central gastric reflexes? what are they under control by?

gastroenteric reflex and gastroileal reflex; under autonomic control

82

which gastric reflex increases motility secretion?

gastroenteric reflex

83

which gastric reflex triggers opening of ileocecal valve allowing passage of materials from small to large intestine?

gastroileal reflux

84

what are the major functions of the large intestine during peristalsis?

1. reabsorption of water and compaction of content into feces. 2. absorption of inportant vitimins liberated by bacterial action and 3. storage of feces prior to defication

85

what arethe three segments of the large intestine?

card image

cecum, colon, and rectum

86

what does the cecum begin? what does it contain and what is attached to it?

compaction; contains ileocecal valve and has an appendix attached.

87

what does the appendix contain? what is the inflammation of the appendix called?

numerous lymphoid nodules; appendicitis

88

what are the four parts of the colon?

ascending, transverse, descending, and sigmoid

89

why is the rectum expandable? what triggers defecation urge?

for feces storage; fecal material within rectum

90

what are large intestine characteristics associated with fecal production?

diameter is larger and wall is thinner that small intestines, lack of villi, abundance of mucous cells, many intestinal glands dominated by mucous glands; and no digestive enzymes produced

91

what does mucus do in the large intestine?

provides lubercation for drier ad more compact fecal matter

92

which anal sphincter is voluntary? which is involuntary?

external; iternal

93

what two positive feedback loops are involved in defecation reflexes?

long and short

94

which reflex is coordinated by the sacral parasympathetic system and stimulates mass movement into feces?

long reflex

95

what is the other reflex responsible for?

stimulation of myeneric plexus to move feces in sigmoid colon and rectum

96

what are the major accessory digestive organs and what do they do?

*salivary glands-produce saliva with mucins and enzymes
gallbladder- store and concentrate bile
*pancreas- exocrine cells secrete buffers and digestive enzymes
*liver- many functions (200+)
*-also have vital metabolc and endocrine function

97

what is the larges visceral organ?

liver

98

how many lobes does the liver have and what are they?

4- left, right,caudate, and quadrate

99

what separates the left and right lobe ? what surrounds bare area? what marks fecal umbilical vein path?

falciform ligament; coronary ligament extension; round ligament

100

what separates left lobe and caudate lobe?

inferior vena cava

101

where is the quadrate lobe?

between the left lobe and gallbladder

102

what are the structures associated with the liver

card image

gallbladder, common bile duct, and porta hepatis

103

what does the gallbladder do in association with the liver?

stores bile it produces temporarily

104

what does the common bile duct do?

carries bile from the liver and gallbladder to duodenum

105

what does the porta hepatis' function?

entry point for blood vessels and other structures from lesser omentum

106

what are the lobules of the liver separated by?

interlobular septa

107

what is in the corner of each lobule

a portal area or triad

108

what makes up the portal area?

branch of portal vein, branch of hepatic artery, and branch of bile duct

109

what ate the liver lobules composed of?

hepatocytes (liver cells)

110

what are liver sinusoids? where do they drain?

blood vessel with nutrients and solutes and are regulated by hepatocytes central vein

111

what else is found within the liver lobules?

phagocytic kupffer cells

112

give the steps of bile movement in the liver after it is secreted.

secreted bile drains into bile canaliculi then bile ductules then bile ducts of the portal triad

113

what is an effect if alcoholism and hepatitis?

degenerative changes in liver and constriction of blood supply

114

what can increased pressure die to clot or damage create? what are some things this may lead to?

portal hypertension; vessel distension and rupture or ascities due to serous fluid leakage

115

what are the three regions of the gallbladder?

fundus, body and neck

116

where does the gallbladder drain fluid?

cystic duct

117

what does the cystic duct merge with and what does it create

right and left common hepatic duct of liver to become common bile duct

118

besides storing bile, what else does the gallbladder do?

concentrate it

119

when and where is the bile released? what hormone controls it?

at mealtime into duodenum when hepatopancreatic sphinter is relaxed; CCK

120

what doe bile salts do? what is this process called?

break lipid droplets apart; emulsification

121

where is the pancreas

posterior to the stomach

122

what are the three parts of the pancreas?

head body and tail

123

what does the pancreatic duct meet and where? what does it do?

common bile duct at duodenal papilla and drains pancreatic juice into duodenum

124

what occurs in 3% to 10% of people

accessory pancreatic duct

125

what are pancreatic acini? what do they secrete?

organizational units made from pancreatic aciner cells; pancreatic enzymes

126

what can peridontal disease cause?

gingivitis, tooth decay, and tooth loss

127

what is mumps? where is it usually?

infection of salivary glands; parotid salivary gland

128

what other organs can mumps affect?

gonads and meninges

129

what is esophagitis usually caused by?

escaping stomach acids (GERD)

130

what can cause hepatitis?

drugs, alcohol, or infection

131

what is cirrhosis?

replacement of hepatocytes with scar tissue

132

what do the hepatitis viruses do?

destroy the liver cells

133

what causes the yellowness if skin and eyes with juandice?

accumulation of bilirubin

134

what are gallstones?

crystals of insoluble minerals and salts forming when bile becomes too concentrated.

135

what causes cholecystitis?

when gallstones block cystic duct

136

what can cause pancreatitis? where is it normally found?

duct blockage, viral infection, or toxic drugs; dogs

137

what are two types of peptic ulcers?

gastric and duodenal

138

what are over 80% of ulcers caused by? what are treatments for ulcers?

infection of helicobactor pylori bacterium; acid reducers or antibiotics for h. pylori if present.

139

what is what cause of enteritis and what does this disease cause?

infection by hiardia lamblia; diarrhea

140

what is dysentery and what does it cause?

inflammation of small and large intestine and causes bloody diarrhea

141

what gastritis?

inflammation of stomach lining

142

what is gastroenteritis? what causes it and where is it ususally found?

inflammation of stomach lining and intestine; pathogenic infection and found often in areas with poor sanitation and low water quality

143

what causes the diarrhea or constipation associated with colitis?

d- too much fluid or absorption capabilities compromised
c- excess water reabsorption due to slow moving feces

144

what people are more susceptible to colerectal cancer? what does this disease begin as?

people over 50 with diets that are high in animal fat and low in fiber; small localized tumors. (polyps)