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Anatomy and Physiology 2B > Digestive System > Flashcards

Digestive System Flashcards

1
Q

What is the digestive system?

A

The organ system that processes food, extracts nutrients, and eliminates residue

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2
Q

What are the five stages of digestion?

A
  • Ingestion
  • Digestion
  • Absorption
  • Compaction
  • Defecation
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3
Q

What are the two types of digestion?

A

Mechanical and chemical

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4
Q

What is mechanical digestion? where is it done and what is its benifet

A
  • The physical breakdown of food into smaller parts
  • Teeth, stomach, small intestine
  • Exposes food surface to enzymes
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5
Q

What is chemical digestion?

A

A series of hydrolysis reactions that break dietary macromolecules into monomers

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6
Q

What carries out chemical digestion?

A

Digestive enzymes

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7
Q

Where are digestive enzymes produced?

A

Salivary glands, stomach, pancreas, and small intestine

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8
Q

What are some nutrients that do not need to be digested and are available in usable form when ingested?

A
  • Vitamins
  • Amino acids
  • minerals
  • cholesterol
  • Water
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9
Q

What are the two subdivisions of the digestive system?

A

The digestive tract and the accessory organs

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10
Q

The digestive tract is also know as the___

A

Alimentary canal

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11
Q

What is the digestive tract?

A
  • 30 ft long tube

- from mouth to large intestins

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12
Q

What is the GI tract?

A

the stomach and intestines

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13
Q

What are accessory organs of the digestive system?

A

Teeth, tongue, salivary glands, liver,

gallbladder, and pancreas

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14
Q

Most of the digestive tract has a similar structural plan consisting of a layered _____

A

Wall

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15
Q

What are the general layers of the digestive tract organs? 4

A
  • Mucosa
  • submucosa
  • muscularis externa
  • serosa
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16
Q

What are the three layers of the mucosa?

A
  • Epithelium
  • Lamina propria
  • Muscularis mucosae
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17
Q

What are the layers of the muscularis externa?

A
  • the inner circular layer

- the outer longitudinal layer

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18
Q

What are the two layers of the serosa?

A
  • Areolar tissue

- Mesothelium

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19
Q

What lymphatic tissue is found in the mucosa?

A

(MALT)

Mucosa-associated lymphatic tissue

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20
Q

Where does the serosa begin and end?

A

Begins in the lower esophagus ends just before the rectum

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21
Q

What is the enteric nervous system?

A

Nervous network in esophagus, stomach, and intestines that regulates digestive tract motility, secretion, and
blood flow

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22
Q

What are the two networks of neurons that make up the enteric nervous system?

A
  • The submucosal plexus: glandular secretions and movment of mucosae
  • Myenteric plexus: peristalsis and other contractions of muscularis externa
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23
Q

What are mesenteries?

A

connective tissue
sheets that suspend stomach and
intestines from abdominal wall

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24
Q

What is the function of the mesenteries?

A

To provide support, blood flow, and lymphatic flow to the abdominal digestive organs

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25
Q

What is the lesser omentum?

A

—a ventral
mesentery that extends from
the lesser curvature of the
stomach to the liver

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26
Q

What is the parietal peritoneum?

A

a serous membrane that lines the wall of the abdominal cavity

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27
Q

What is the Greater omentum?

A

A mesentery that hangs from the greater curvature of the stomach and covers the small intestine like an apron

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28
Q

What is the mesocolon?

A

an extention of the mesentery that anchors the colon to the abdominal wal

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29
Q

What are the three mechanisms that control motility and secretion of the digestive tract?

A
  • Neural control
  • Hormones
  • Paracrine secretions
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30
Q

The oral/buccal cavity is composed of?

A

The mouth enclosed by cheeks, lips, palate, and tongue

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31
Q

What tissue lines the mouth?

A

Strat. squam. epithelium

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32
Q

The tongue is attached to the floor of the mouth at the?

A

Lingual frenulum

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33
Q

The border between the body and the root of the tongue is marked by?

A

Vallate papilae

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34
Q

What portion of the tongue produces saliva?

A

The lingual glands located amid the extrinsic muscles(muscles that attach tongue to mouth)

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35
Q

What are the four regions of a tooth?

A
  • Crown
  • Neck
  • Root
  • Gingival sulcus
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36
Q

What is the hard yellowish tissue that makes up most of the tooth?

A

Dentin

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37
Q

What is oral plaque?

A

a sticky residue on the teeth made up of bacteria and sugars

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38
Q

What is dental calculus?

A

calcified plaque

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39
Q

What is the first step in mechanical digestion?

A

Mastication

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40
Q

What are the main functions of saliva?

A
  • Moisture to mouth and food(lubrication)
  • Starch and fat digestion
  • Dissolves molecules to activate taste buds
  • Inhibits bacterial growth
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41
Q

Salivary glands are composed of ____ glands that are branched and end in a ___

A
  • Tubuloacinar

- Acini

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42
Q

What are the different types of cells within a acini that secrete substances?

A
  • Mucous cells: secrete mucous

- Serous cells: secrete thin fluid rich in enzymes and electrolytes

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43
Q

Where is the neural control for salivation located?

A

-The salivatory nuclei in the medulla oblongata and pons

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44
Q

What are some triggers of salivation?

A
  • Tactile, pressure, and taste receptors

- odor, sight, though of food

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45
Q

How does parasympathetic stimulation effect salivation?

A

results in an abundance of thin enzyme rich saliva

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46
Q

how does sympathetic stimulation effect salivation?

A

results in less, thick saliva with more mucus

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47
Q

What is the function of the lower esophageal sphincter?

A

to prevent regurgitation

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48
Q

What is the swallowing center and where is it located?

A

-A pair of nuclei in the medulla oblongata that coordinates swallowing

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49
Q

What are the three phases of swallowing?

A
  • Oral
  • Pharyngeal
  • esophageal
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50
Q

What are the empty, after meal, and full capacity of the stomach

A
  • 50ml
  • 1 to 1.5 L after meal
  • up to 4L
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51
Q

What is chyme?

A

soupy or pasty mixture of semi-digested food in the stomach

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52
Q

What are the four regions of the stomach?

A

– Cardial part (cardia)—small area within about 3 cm of the cardial orifice
– Fundus (fundus)—dome-shaped portion superior to esophageal
attachment
– Body (corpus)–makes up the greatest part of stomach
– Pyloric part—narrower pouch at
the inferior end

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53
Q

What are the four subdivisions of the Pyloric portion of the stomach?

A
  • Funnel like antrum
  • Pyloric canal
  • Pylorus
  • Pyloric sphincter
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54
Q

Where does parasympathetic innervation of the stomach come from?

A

Vagus Nerve

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55
Q

Where does sympathetic innervation of the stomach come from?

A

Celiac ganglia

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56
Q

What is the path of blood to and from the stomach?

A
  • Supplied by the celiac trunk

- drained blood from stomach and intestines filter through the liver via the hepatic portal circulation

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57
Q

The mucosa of the stomach is composed of ___ epithelium?

A

Simple columnar

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58
Q

The apical regions of the stomachs surface cells are filled with____

A

mucin

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59
Q

What is mucin?

A

a substance that swells with water and becomes mucus after it is secreted

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60
Q

The muscularis externa of the stomach has ___ layers instead of the normal 2

A

3

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61
Q

What are the three layers of the muscularis externa of the stomach?

A
  • Outer longitudinal,
  • middle circular
  • inner oblique
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62
Q

What are gastric pits?

A

depressions in gastric mucosa that contain tubular glands at the bottom

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63
Q

What are the three types of tubular glands found in the gastric pits?

A
  • Cardiac glands in the cardial part
  • Pyloric glands in pyloric part
  • Gastric glands in the rest
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64
Q

The cardial and pyloric glands of the gastric pits are primarily ___ cells

A

Mucous

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65
Q

What are parietal cells?

A
  • Cells found mostly in the upper half of gastric pit glands

- They produce HCL, intrinsic factor, and ghrelin

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66
Q

What are cheif cells?

A
  • The most numerous of the cells in the pits of the body of the stomach
  • secrete gastric lipase and pepsinogen
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67
Q

What are enteroendocrine cells?

A

cells located in the lower end of the pit glands that produce paracrine messengers that regulate digestion

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68
Q

What is gastric juice and how much is produced each day?

A
  • A mixture of water, HCl, and Pepsin
  • 2 to 3L a day
  • produced by gastric glands
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69
Q

How is HCl produced?

A
  • Produced in the parietal cells using CAH
  • CO2 is taken into the cell and turned into carbonic acid
  • Carbonic acid is then split and H+ is transfered out of cell into lumin , K+ is pumped in
  • Chloride is taken from blood through the cell and into lumin
  • Hydrogen ion and chloride ion bond to form HCl
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70
Q

What are the functions of HCl in the stomach?

A
  • Activates Pepsin and lingual lipase
  • breaks down connective tissue and plant cell walls
  • Converts iron into a digestable form
  • Contributes to nonspecific immunity
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71
Q

What is Alkaline tide?

A

elevated bicarbonate levels when digestion occurs due to the production of HCl

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72
Q

What are zygomens?

A

Digestive enzymes secreted as inactive proteins

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73
Q

What is pepsinogen?

A
  • the zymogen secreted by the chief cells

- inactive form of pepsin

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74
Q

How is pepsinogen converted to pepsin?

A
  • HCl removes some of its amino acids

- It is also autocatalyic meaning that some of the pepsin from will convert more pepsinogen into pepsin

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75
Q

What is the function of pepsin?

A

To digest dietary protein into shorter peptides

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76
Q

Where is protein digestion completed?

A

in the small intestines

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77
Q

What are the functions of Gastric and lingual lipase?

A

They work to digest fats in the stomach

-only digest 10-15%

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78
Q

What is intrinsic factor?

A
  • A glycoprotein produced by the parietal cells
  • Essential for the absorption of B12 by its action of binding to B12 which allows it to be absorbed by the small intestine
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79
Q

How much chyme is passed into the small intestine at a time?

A

3mL

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80
Q

What are the three ways that the stomach is protected from its harsh environment?

A
  • Mucous coat
  • Tight junctions: prevent seeping gastric juice
  • Epithelial cell replacement: replaced ever 3 to 6 days
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81
Q

How is gastric function regulated?

A

By a collaboration between the endocrine system and the nervous system

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82
Q

What are the three phases of gastric activity?

A
  • Cephalic phase
  • Gastric phase
  • Intestinal phase
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83
Q

How does ingested food stimulate the gastric phase?

A
  • By stretching

- By increase of pH

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84
Q

What three chemicals stimulate gastric secretion?

A
  • Acetylcholine: parasympathetic nerve fibers
  • Histamine: enteroendocrine cells in gastric glands
  • Gastrin: g cells in pyloric glands
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85
Q

Explain the intestinal phase of gastric activity

A
  • an inital increase in gastric activity

- Soon is inhibited by the enterogastric reflex

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86
Q

What are the four lobes of the liver?

A

Right, left, quadrate, and caudate

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87
Q

The ___ ligament separates the right and left lobe of the liver

A

falciform ligament

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88
Q

What are hepatic lobules?

A

tiny cylinders that fill the interior of the liver

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89
Q

What are hepatocytes?

A

Cuboidal cells surrounding the central vein forming plates up the lobule

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90
Q

What are hepatic sinusoids?

A

blood filled channels lined by fenestrated endothelium that fill up spaces between plates

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91
Q

Blood leaves the liver at its ____ surface

A

superior

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92
Q

Trace the flow of bile from the liver to the small intestine

A
  • Flows from the liver via Bile canaliculi
  • Passes into bile ductiles
  • then to the right and left hepatic ducts which fomr the common hepatic duct
  • passes the cystic duct or flows from the cyctic duct
  • then down the bile duct
  • combines with the duct of the pancreas and into the small intestine
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93
Q

When the bile duct and pancriatic duct converge it creates the___

A

Hepatopancreatic ampulla

94
Q

What is the function of the gallbladder?

A

To store and concentrate bile

95
Q

What is bile?

A

Yellow-green fluid containing minerals, cholesterol, neutral fats,

96
Q

What is bilirubin?

A

The principal pigment derived from the decomposition of hemoglobin

97
Q

Where is bilirubin metabolized into urobilinogen?

A

in the large intestine by bacteria

98
Q

What are bile acids synthesized from?

A

cholesterol

99
Q

___% of bile is reabsorbed in the ileum and returned to the liver

A

80%

100
Q

What is the body’s only way of eliminating excess cholesterol

A

Bile acids that are excreted into the feces and more cholesterol is used to make more bile acids

101
Q

How much pancreatic juice is secreted per day?

A

1200 to 1500 mL

102
Q

___ release their secretions into small ducts that converge on pain pancreatic duct

A

Acini

103
Q

The pancreatic duct joins the bile duct at the?

A

Heptopancreatic ampulla

104
Q

What is pancreatic juice?

A

an alkaline mixture of water, enzymes, zymogens, sodium bicarbonate, and electrolytes

105
Q

In the pancreas the ___ secrete enzymes and the ___ secrete sodium bicarb

A

Acini

Ducts

106
Q

What are the three pancreatic zymogens?

A
  • Trypsinogen
  • Chymotrypsinogen
  • Procarboxypeptidase
107
Q

What converts trypsinogen?

A
  • Converted to trypsin by enteropeptidase which is secreted by the mucosa of the small intestine
  • trypsin is also autocatalytic, it converts trypsinogen into more trypsin
108
Q

What converts chymotrypsinogen?

A
  • is converted into trypsinogen by trypsin
109
Q

What converts procarboxypeptidase?

A

-It is converted to carboxypeptidase by trypsin

110
Q

What is the function of pancreatic amylase?

A

to digest starch

111
Q

What is the function of pancreatic lipase?

A

to digest fats

112
Q

What is the function of Ribonuclease? where is it found?

A

to digest RNA

-found in the small intestine from pancreas

113
Q

What is the function of deoxyribonuclease? where is it found?

A

To digest DNA

-found in the small intestine from pancreas

114
Q

What are the three stimuli that regulate the release of pancreatic juice and bile?

A
  • Acetylcholine
  • Cholecystokinin
  • Secretin
115
Q

What is the effect of Acetylcholine on pancreatic juice secretion? where does it come from?

A
  • Comes from vagus and enteric nerves
  • Stimulates acini to secrete enzymes during cephalic control
  • DOES NOT STIMULATE RELEASE JUST PRODUCTION
116
Q

What is the effect of Cholecystokinin on pancreatic juice secretion? where does it come from?

A
  • Secreted by the mucosa of duodenum in responce to fat in the small intestines
  • Stimulates acini to secrete enzymes
  • Strong stimulation of gallbladder
  • induces contractions of gallbladder and relaxation of hp sphincter
117
Q

What is the effect of secretin on pancreatic juice secretion? where does it come from?

A
  • Released from the duodenum in response to acidic chyme arriving from the stomach
  • Stimulates liver and pancreas ducts to secrete more sodium bicarb
  • raises pH to level required for enzyme activity in small intestines
118
Q

What are the three main regions of the small intestine?

A
  • Duodenum
  • Jejunum
  • ileum
119
Q

Where does the duodenum begin?

A

At the pyloric valve

120
Q

The duodenum ends in a sharp bend called the ___

A

Duodenojejunal flexure

121
Q

What are the four major events of digestion that occur in the duodenum?

A
  • Stomach acid neutralization
  • Emulsification of fats via bile acids
  • inactivation of pepsin
  • Chemical digestion via pancreatic enzymes
122
Q

Where does most of the nutrient absorption occur?

A

in the Jejunum

123
Q

Why does the Jejunum have such a rich blood supply?

A

because it is the sight of most of the nutrient absorption in the body

124
Q

list the regions of the small intestine’s in order

A
  • Duodenum
  • Jejunum
  • Ileum
125
Q

What is the ileocecal junction?

A

End of the small intestine where the ileum joins the cecum of the large intestine

126
Q

What is the ileocecal valve and what forms it? its function?

A
  • a sphincter formed by the thickened muscularis of the ileum
  • functions to regulate the passage of waste into the large intestine
127
Q

Where does the small intestine receive its blood supply from?

A
  • The superior mesenteric artery

- leaves via the superior mesenteric vein

128
Q

What is the form and function of the plicae circularis?

A
  • Circular folds that increase the surface area of the small intestine
  • involve only the mucosa and sub mucosa
  • function to cause chyme to spiral through the intestine increasing its exposure to surface area
129
Q

The plicae circulares increase surface area by a factor of___

A

2-3

130
Q

Villi increase surface area by a factor of ___

A

10

131
Q

Micro villi increase surface area by a factor of ___

A

20

132
Q

the lumen of the small intestine is lined with___

A

simple columnar epithelium

133
Q

What are the two types of cells that cover villi?

A
  • Absorptive cells

- goblet cells

134
Q

How does the epithelium of the digestive system protect itself from digestive enzymes?

A

Via tight junctions prevent the seeping of enzymes

135
Q

What type of tissue makes of the core of a villi? What is this core called?

A
  • Areolar tissue

- The lamina propria

136
Q

The micro villi on the absorptive cells of the villi make up the ___ border

A

Brush

137
Q

What is the function of the brush border?

A

To produce enzymes that carry out final parts of enzymatic digestion

138
Q

How does the brush border deliver its enzymes?

A

via contact

139
Q

What are intestinal crypts?

A

pores on the floor of the small intestine between villi that open into tubular glands

140
Q

Absorptive cells as also called___

A

Enterocytes

141
Q

What type of cells make up the surface of the intestinal crypts?

A
  • Upper half is the same as villi (goblet and absorptive)

- Lower half is active stem cells

142
Q

Other than stem cells, what other cells are found at the bottom of intestinal crypts? what are their functions

A
  • Paneth cells

- Secrete defensive proteins to resist bacterial invasion

143
Q

What are the duodenal glands and where are they found?

A
  • Found in the submucosa of the duodenum

- Secrete bicarb rich mucus that neutralizes stomach acid

144
Q

Where in the small intestine do a majority of the lymphocytes live

A

The lamina propria and the submucosa

145
Q

What is the main secretion of intestinal crypts? how much per day is secreted?

A

Intestinal juice

1-2 L a day

146
Q

What is intestinal juice and when is it released?

A
  • A mixture of water, mucus, and a little enzyme
  • pH of 7.4 to 7.8
  • Released in response to acid, hypertonic chyme, and intestinal distension
147
Q

What three functions does the contraction of the small intestines surve?

A
  • To mix chyme with Intestinal hjuice, bile, and pancreatic juice
  • To churn chyme
  • to move residue towards large intestines
148
Q

What is intestinal segmentation?

A

-The moment of stationary ring like contractions along the intestine

149
Q

What are the beinfits of segmentation?

A

Variations in contraction times causes a random rhythm which allows chyme to reach maximum surface area contact before moving to large intestine

150
Q

What controls the pace of segmentation?

A

Enteric pacemaker cells in the muscularis externa

151
Q

When does segmentation decline and peristalsis begin?

A

When most nutrients have been absorbed

152
Q

What is peristalsis? what hormone triggers it?

A
  • A series of wave like contractions that move food from the small intestines to the colon
  • Triggered by motilin
153
Q

Where does peristalsis begin? how long does the process take?

A
  • the duodenum

- 2 hours

154
Q

When does the ileocecal valve open?

A

-When food in the stomach triggers the gastroileal reflex that triggers segmentation and the relaxation of the valve

155
Q

When does the ileocecal valve close?

A
  • It is normally closed

- Closes when the cecum fills with residue and the pressure pinches the valve shut

156
Q

Where does the digestion of starch begin? what enzyme is at play?

A

in the mouth via salivary amylase

157
Q

What is the chain of breakdown for a starch?

A
  • Starch is digested into oligosaccharides
  • then into the disaccharide maltose
  • Maltose into glucose
158
Q

What percentage of starch is broken down via salivary amylase?

A

50%

159
Q

What happens to starch after the mouth?

A
  • Salivary amylase is quickly denatured by the stomach (only functions at a pH of 6.8 to 7.0)
  • Digestion is resumed in the small intestine via pancreatic amylase
160
Q

what occurs After starch is broken down into oligosaccharides and maltose

A

Brush border enzymes continue digestion

161
Q

What brush border enzymes hydrolyze oligosaccharides?

A

Dextrinase and Glucoamylase

162
Q

What brush border enzymes hydrolyze maltose?

A

Maltase

163
Q

What brush border enzymes hydrolyze the disaccharides sucrose and lactose?

A

Sucrase and lactase

164
Q

What is the fate of monosaccharides in the small intestines?

A

They are immediately absorbed

165
Q

What percentage of absorbed sugar is glucose?

A

80%

166
Q

How is glucose absorbed at the brush border?

A

Via a sodium-glucose transport protein

167
Q

What happens to the sugars once they are absorbed?

A

they are transported out of the cell via facilitated diffusion and absorbed into bloodstream to go to the liver

168
Q

How is galactose absorbed?

A

Via the same Sodium-glucose transporter as glucose

169
Q

How is fructose absorbed?

A

Via facilitated diffusion

170
Q

What happens to fructose after it is absorbed and before it is transported out of the cell?

A

A majority of it is converted into glucose

171
Q

Other than through the ICF how else is glucose absorbed at the brush border?

A
  • Solvent drag caused by the increased osmolarity of the ECF due to sugars leaving the epithelial cells.
  • Due to leaky tight junctions
172
Q

What are the three main sources of Protein?

A 
Exogenic
   -Dietary
-Endogenic
   -Digested digestive 
   enzymes
   -Sloughed epithelial 
   cells
173
Q

How many grams of amino acids come from endogenic routes?

A

30g/day

174
Q

How many grams of amino acids come from exogenous routes?

A

about 60g/day

175
Q

What types of enzymes digest proteins?

A

Proteases(peptidases)

176
Q

Where does protein digestion begin?

A

in the stomach via pepsin

177
Q

How does pepsin work?

A

it hydrolyzes any peptide bond between thyrosine and phenylalanine

178
Q

What percentage of protein is digested via pepsin?

A

10-15%

179
Q

What enzymes take over protein digestion after the stomach?

A

Trypsin and chymotrypsin

180
Q

How do trypsin and chymotrypsin continue protein digestion?

A
  • They hydrolyze polypeptides into shorter oligopeptides

- O-peptides are then taken apart one amin acid at a time

181
Q

What are the three enzymes responsible for dismantling oligopeptides?

A
  • Carboxypeptidase
  • Aminopeptidase
  • Dipeptidase
182
Q

What is the role of Carboxypeptidase in protein digestion?

A

COmes from the pancreas

-Removes amino acids from the carboxyl end of the chain

183
Q

What is the role of aminopeptidase in protein digestion?

A
  • Brush border enzyme

- removes amino acids from the -NH2 end of the chain

184
Q

What is the role of dipeptidase in protein digestion?

A
  • brush border enzyme

- Splits dipeptides in the middle to release two free amino acids

185
Q

How are proteins absorbed?

A

Once converted into free amino acids they are absorbed into the intestinal epithelial cells via sodium dependent amino acid cotransporters

186
Q

How are absorbed amino acids transported into the bloodstream?

A

facilitated diffusion

187
Q

why is lipid digestion complicated?

A

Because lipids are hydrophobic

188
Q

What are lipases?

A

Fat digesting enzymes

189
Q

Where does lipid digestion begin?

A

In the mouth via lingual lipase secreted by the intrinsic salivary glands

190
Q

What % of lipids are digested before the small intestines?

A

10-15%

191
Q

Before it reaches the duodenaum what does the stomach do the lipids to make digestion easier?

A

It emulsifies it through vigorous pumping in the antrum

192
Q

What breaks down emulsification droplets once in the smal intestine? why is this benificial?

A
  • Bile, Lecithin, and -agitation

- Exposes more fat surface to enzymes

193
Q

Lipase acts specifically on ___

A

Triglycerides

194
Q

How does lipase act on triglycerides?

A

-By removing the first and third fatty acids from the glycerol backbone

195
Q

What is the product of lipase action?

A

Two free fatty acids and a mono glyceride

196
Q

How are free fatty acids, monoglycerides, and other lipids absorbed?

A
  • They are absorbed via Micelles in the bile

- after absorption they are transported and passed through the plasma membrane of the absorptive cells

197
Q

What are micelles?

A
  • 20-40 bile acids arranged with their hyydrophilic sides on the outside
  • has a core of cholesterol and phospholipids
198
Q

What happens to lipids once they are transported into the intestinal cells?

A
  • They are transported to the ER and re-synthesized into triglycerides
  • then given a coat of phospholipids and protein in the golgi
  • Become chylomicrons at that point
199
Q

What happens to chylomicrons?

A

They are taken up by lacteal into the lymph and eventually enters the bloodstream

200
Q

What is chyle?

A

fatty intestinal lymph

201
Q

What enzymes are responsible for digesting nucleic acids?

A

Nucleases (Deoxyribonuclease and ribonuclease)

202
Q

How do nucleases work? and where?

A
  • At the brush border

- Split nucleic acids into phosphate ions, sugar base, and nitrogenous bases

203
Q

How are the products of nucleic acid digestion absorbed?

A

Membrane carriers

204
Q

How are vitamins digested?

A
  • the remain unchanged and are absorbed as is either with other lipids if lipid soluble
  • absorbed via diffusion if water soluble
  • b12 needs to be bound to intrinsic factor first
205
Q

Where are minerals absorbed?

A

in the small intestines

206
Q

How is sodium absorbed?

A

it is co-transported with sugars and amino acids

207
Q

How is chloride absorbed?

A

It is exchanged for bicarb reversing chloride-bicarb exchange that occurs in the stomach

208
Q

How is potassium absorbed?

A

Simple diffusion

209
Q

How much iron and calcium is absorbed?

A

only what is needed

210
Q

How is iron absorbed?

A

Active transport of ferrous ions (Fe2+)

211
Q

How is calcium absorbed?

A
  • Transcellular in the dupdenum

- Diffusion between cells in the jejunum and ileum

212
Q

How does vitamin D effect calcium absorption?

A

It affects absorptive cells of the dupdenum by increasing the nummber of calcium channels

213
Q

What does parathyroid

hormone stimulate when calcium levels are low?

A

The production of vit. D in the kidneys

214
Q

How is water absorbed in the small intestines?

A

Via osmosis following the absorption of salts and organic nutrients

215
Q

What causes diarrhea?

A
  • When the large intestine absorbs too litter water.

- occurs when feces passes too quickly or there are high concentrations of solutes (Like undigested lactose)

216
Q

What causes constipation?

A

When fecal movement is slow and too much water is absorbed.

217
Q

What are the taeia coli?

A

Longitudinal fibers of the muscularis externa of the large intestine.

218
Q

What are the haustra of the large intestine?

A

Pouches in the colon caused by the muscle tone of the teaniae coli

219
Q

The internal anal sphincter is composed of___

A

the smooth muscle of the muscularis externa

220
Q

The external anal sphincter is composed of?

A

Skeletal muscle of pelvic diaphragm

221
Q

WHat are the omental appendages?

A

Club like fatty pouches of peritoneum adhering to the colon. Unknown function

222
Q

The intestinal crypts of the large intestine have a high concentration of ____ cells

A

Goblet

223
Q

The gut microbiome is responsible for the digestion of ___

A
  • Cellulose, pectin, and other undigestable carbs

- help to synthesize b vitamins and K vits

224
Q

The main function of the large intestine is to ____

A

reabsorb water and electrolytes.

225
Q

What ar the two types of contractions within the large intestine?

A
  • Haustral contractions-every 30 mins

- Mass movements- 1-3 times a day

226
Q

What action stimulates the movment of the colon?

A

Gastrocolic and duodenocolic reflexes (Filling of stomic and duodenum)

227
Q

What are the two defecation reflexes and what triggers them?

A
  • triggered by the stretching of the rectum
  • Intrinsic defecation reflex
  • Parasympathetic defecation reflex
228
Q

What is the intrinsic defecation reflex?

A
  • A weak response to rectal stretching

- Relaxes the internal sphincter

229
Q

What is the parasympathetic defecation reflex?

A
  • rectal stretching causes sensory signal to spinal cord

- pelvic nerve returns signal and intensify’s peristalsis while also relaxing the internal anal sphincter

230
Q

How is defecation controlled?

A

Through voulntary control of the external sphincter and puborectlis muscles

Anatomy and Physiology 2B (7 decks)

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