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Bio 66 > Chapter 18 The Digestive System > Flashcards

Chapter 18 The Digestive System Flashcards

(136 cards)

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1
Q

MOTILITY is

A

Movement of food through the gastrointestinal (GI) tract via:
Ingestion
mastication
deglutition
contraction of smooth muscles: peristalsis, segmental contractions

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2
Q

SECRETION is

A

Release of exocrine and endocrine secretions into lumen of GI tract for digestion

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3
Q

DIGESTION is

A

Chemical/mechanical breakdown of food from macromolecules to smaller molecules, for absorption

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4
Q

ABSORPTION is

A

Transport of digested end products into blood/lymph

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5
Q

STORAGE AND ELIMINATION is

A

Temporary storage followed by elimination of indigestible food molecules

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6
Q

IMMUNE BARRIER is

A

Immune system cells in connective tissue outside of intestinal epithelium AND physical barrier to pathological organisms and toxins due to tight junctions in epithelial lining of intestine.

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7
Q

How does digestion occur by

A

hydrolysis reactions

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8
Q

Gastrointestinal (GI) Tract/Alimentary Canal is made up of

A 
Mouth
pharynx
esophagus
stomach
small intestine
large intestine
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9
Q

Accessory Organs and Tissues are made up of

What do they do

A 
Teeth
tongue
salivary glands
liver
gallbladder
pancreas

Secrete substances into the tract via connecting ducts

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10
Q

What does the mouth produce

A

Salivary amylase
Lipase
Water

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11
Q

What does the stomach produce

A

HCL
Pepsinogen
Mucus
Intrinsic Factor

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12
Q

What does the Small intestine produce

What do they do

A

Bile
Bicarbonate
Enzymes

Absorb nutrients

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13
Q

What does the large intestine do

A

Absorb water/vitamins

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14
Q

What are the 4 layers of the gut wall

A

Mucosa
Submucosa
Muscularis
Serosa

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15
Q

What is the first layer (innermost)

What does it do

What is unique about it and what does this do

A

MUCOSA:

Absorption and secretion
Mucus secretion

Muscularis mucosae (FOLDS):
Folds increase surface area for absorption
Produces movement of villi

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16
Q

What is the second layer

What does it have

A

SUBMUCOSA:

Connective tissue that serves mucosa
Blood/lymph vessels

Submucosal plexus: neuronal innervation for muscularis mucosae

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17
Q

What is the third layer

What is its main function

What is different between its outside and inside

A

MUSCULARIS EXTERNA:

Involved in segmental and peristaltic contractions, to move food through tract, and pulverize and mix it with digestive enzymes

Inner circular layer of smooth muscle

Myenteric plexus: neurons for entire GI tract

Outer longitudinal layer of smooth muscle

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18
Q

What is the fourth layer (Outermost)

A

SEROSA:

Connective tissue covered with epithelium

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19
Q

What lines the lumen in the gut

A

Absorptive cells

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20
Q

Where are the neural and muscular components in the gut

A

below the lumen

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21
Q

Blood and lymph vasculature are abundant to transport absorbed nutrients

A

True

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22
Q

What do the villi do

A

Increase the surface area for absorption of nutrients

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23
Q

What is Mastication

A

chewing of food in mouth

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24
Q

What does salivary amylase digest

A

Starch (carbohydrate)

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25
What is Deglutition
Swallowing
26
What does food and drink stimulate What does this result in
pressure receptors in the pharynx afferent input to the medulla and efferent output to muscles in pharynx and esophagus
27
What is a bolus
mix of food with saliva
28
What prevents food from entering the nasal passages
Soft palate
29
What closes off the opening to the larynx
Glottis
30
What prevents food from entering the trachea
Epiglottis
31
What relaxes to allow food to descend into the esophagus
esophageal sphincter
32
What is Peristalsis
wavelike muscular contraction that pushes bolus to the stomach
33
What allows for the bolus to be pushed down the esophagus to the stomach What happens just before reaching the stomach
Circular smooth muscle contracting behind bolus and relaxing in front The lower esophageal sphincter muscle relaxes
34
What is Chyme
Partially digested food with gastric juices
35
What does the stomach do (5)
1. Stores food 2. Kills bacteria with acidity of gastric juice 3. Starts digestion of proteins (not carbs or fats) 4. Peristaltic waves mix and propel the chyme 5. Moves chyme to the small intestine, where most digestion and absorption occur
36
What does the inner surface of the stomach contain
Folds called gastric rugae
37
What 4 things do specialised cells in the stomach produce
Mucus fluid Enzyme precursors Hydrochloric acid Hormones
38
What secretes mucus in the stomach
Mucous neck cells
39
What secretes Pepsinogen in the stomach
Chief (zymogenic) cells
40
What secretes Hydrochloric acid in the stomach
Parietal cells
41
What secretes Histamine and serotonin in the stomach
Enterochromaffin like cells
42
What secretes gastrin
G cells
43
What secretes somatostatin
D cells
44
What secretes intrinsic factor
Gastric mucosa
45
What does intrinsic factor do
Allows for intestinal absorption of vitamin B12
46
What does ghrelin do
regulates hunger
47
What is gastric juice
Secretions of gastric cells + water
48
What does acid production by parietal cells depend on
Carbonic acid Secretion of hydrogen into the stomach (active transport by H/K atpase pumps)
49
What happens when carbonic acid dissociates in the stomach
Bicarbonate secreted into the bloodstream Exchanged for Cl via facilitated diffusion
50
What stimulates the secretion of HCl What inhibtis secretion of HCl
Gastrin ACh Histamine Somatostatin
51
What stimulates gastrin
Presence of partially digested proteins in stomach
52
How does Gastrin effect secretion of HCl (3)
Binds to receptors on parietal cells Stimulates ECL cells to secrete histamine Paracrine stimulation of parietal cells secretes HCl
53
What happens when gastric juice is acidic (3)
Activates pepsin Optimizes activity of pepsin Accelerates digestion of proteins
54
What protects the lining of the stomach
mucus layer containing bicarbonate
55
What converts pepsinogen to pepsin
HCl aciditiy
56
What does pepsin actually do
accelerates the digestion of proteins
57
What does the mucosa in the small intestine contain
Goblet cells for secreting mucus and lymphocytes Folds called Villi Microvilli on villi which increase the surface area for food absorption
58
What do microvilli also have
digestive enzymes
59
The small intestines is where there is digestion of... (3)
Carbohydrates Lipids Proteins
60
The villi in the small intestine project where
into the lumen - increases surface area for absorption
61
What are brush border enzymes
Enzymes on the plasma membrane of microvilli
62
What is the main contraction in the SI and why
Segmentation Mixes and moves chyme Controlled by enteric nervous system
63
The large intestine has no... (2)
Villi or digestion
64
The large intestine absorbs...
Electrolytes Water Vitamins
65
What is haustra
Pouches on outer surface of LI
66
What is the main activity in the LI
Active transport of sodium And Absorption of water To concentrate the feces
67
Microbes in the LI produce... (2)
Vitamin K for blood clotting B vitamins
68
How does defecation occur
Longitudinal rectal muscles contract Increases rectal pressure Internal and external sphincters relax Contraction of abdominal and pelvic muscles
69
Gallbladder function
storage of bile from liver
70
Pancreas function
pancreatic juice (exocrine) for digestion
71
What are the 5 major functions of the liver
``` Detoxication of blood Carbohydrate metabolism Lipid Metabolism Protein synthesis Secretion of bile ```
72
What separates hepatocytes in the liver
Sinusoids
73
What is the passage of blood in the liver (4)
Blood enters a liver lobule through the portal triad Passes through hepatic sinusoids Leaves the lobule through a central vein The central veins converge to form hepatic veins that take venous blood from the liver
74
What are the main components of bile
``` bile pigment bile salts lecithin bicarbonate ions cholesterol trace metals ```
75
What is the bile pigment
Bilirubin - breakdown of heme
76
Characteristics of Bilirubin
Not water soluble = carried in blood attached to albumin Liver converts to water soluble from that can be secreted into bile
77
Bilirubin that is excreted in feces and urine is excreted as
Urobilinogen
78
Bile salts are... They form...
Cholesterol based Micelles
79
Emulsification is the
breakdown of large fat globules by bile salts into smaller globules, for digestion by lipase enzymes
80
The major pathway of cholesterol breakdown is activated when
cholesterol is used to produce bile salts
81
Where in the liver is bile produced Where is it then secreted to
Hepatocytes Bile caniculi
82
The caniculi are drained by...
Bile ducts at end of each lobule
83
Where do the bile ducts transport the bile What then stimulates bile to move into the SI
into the gall bladder Cholecystokinin (CCK)
84
How does bile enter the SI
Via the common bile duct
85
What happens to the cholesterol based bile salts along the intestine
Reabsorbed into the liver
86
What is unique about bile salt structure
Has one polar and one no polar end
87
What do the nonpolar ends of bile acid do
Emusify fats in water
88
What forms in bile acids
Micelles which are readily broken down
89
`What are the endocrine functions in the pancreas
Insulin Glucagon Secreted into the blood
90
What are the exocrine functions of the pancreas
Pancreatic juice Secreted through pancreatic duct into duodenum of SI
91
What is pancreatic juice made up of
Bicarbonate and 20 enzymes
92
What does Amylase digest
Starch
93
What does Trypsin digest
Protein
94
What does Lipase digest
Triglycerides
95
The Exocrine cells in the pancreas produce what type of enzymes they travel via the
Digestive enzymes Pancreatic duct
96
When do digestive enzymes become active
In the SI
97
What are zymogens
Inactive enzyme precursors
98
Gastric motility and secretion is a ______ process This process results in the presence of
automatic Chyme
99
The GI tract is both an
Endocrine gland And Target for hormones
100
The regulation of GI processes can be controlled by
Hormonal (endocrine cells) Neural (enteric nervous system)
101
What are the 3 phases of GI control
Cephalic phase Gastric phase Intestinal phase
102
What happens in the Cephalic phase (3)
Gastric secretion stimulated by sight, smell, taste, chewing, talking about food; continues into first 30 minutes of meal Vagus nerves stimulate chief cells to secrete pepsinogen, parietal cells to secrete HCl, and G cells to secrete gastrin Gastrin stimulates ECL cells to secrete histamine, which stimulates parietal cells to secret HCl
103
What happens in the gastric phase (9) Focus on what cells secrete what and what acidity inhibits
Starts when food enters stomach Casues: distension, acidity, AAs, peptides Presence of AAs and peptides Stimulates chief cells to secrete pepsinogen and G cells to secrete gastrin Stimulates secretion of histamine from ECL cells to stimulate HCL from parietal cells Acidity inhibits gastrin secretion via somatostatin secreted by D cells when pH decreases. Somatostatin also inhibits acid secretion by parietal cells Distension
104
What happens in the Intestinal phase What are the inhibitory hormones secreted by SI
Inhibition of gastric activity and motility by vagus nerves when chyme enters SI = time to digest and absorb food gastric inhibitory peptide (GIP) somatostatin cholecystokinin (CCK) glucagon-like peptide-1 (GLP-1).
105
The myenteric plexus is
the outer network entire length of GI tract
106
The Submucosal plexus is
The inner network Only in SI and LI
107
What is the sensory stimulus that activates interneurons What does this then stimulate
Chyme Motor neurons = smooth muscle contraction
108
Intestinal Reflexes affect what
Motility
109
What does Paracrine Regulation affect
Contraction Absorption Secretion
110
What is Cholecystokinin (CCK)
Protein and fat in chyme stimulate secretion of CCK by duodenum
111
What does the Cholecystokinin stimulate
secretion of pancreatic juice enzymesto digest protein and fat
112
What does Chyme stimulate in the SI What does it inhibit
Gastric phase and reflex secretion of pancreatic juice and bile Inhibits entry of additional chyme into SI, to allow digestion
113
What stimulates secretion of Secretin What does it then stimulate
Reduced pH in SI (due to acidic chyme) Secretion bicarbonate and water secretion from pancreas
114
The secretion of bile is but...
Continuous Does increase with meal
115
What causes bile volume to increase
Secretin and CCK stimulate liver to secrete bicarbonate into bile
116
What causes more bile to be delivered to the duodenum from the contracting gallbladder
Chyme in duodenum CCK secretion in response to fat in chyme
117
During a meal, the arrival of bile in the duodenum causes what to happen
Liver to secrete more bile
118
Salivary amylase digests from...
mouth to upper stomach
119
Pancreatic amylase digests in... Results in..
SI Results in Disacc, trisacc, oligosacc
120
Brush border amylases hydrolyze in Results in..
SI hydrolyse into their components monosaccharides
121
How are carbohydrates absorbed
Via secondary active transport coupled to Na into SI Then via facilitated diffusion in membrane
122
When Na is absorbed what follows
CL follows passively Water then follows NaCl for absorption into blood
123
How do AAs enter the cells of the SI
via secondary active transport coupled to Na
124
Where are Dipeptides and tripeptides transported into How... What happens to them when they get there
epithelial cells of SI via a different carrier hydrolyzed into AAs in the cytoplasm
125
Lipids in chyme stimulate what into the SI This results in
Bile Emulsification
126
Digestion of lipid droplets in SI is by
Pancreatic lipase Aided by colipase - bind lipases with lipid droplet
127
What does Phospholipase A digest
Phospholipids into fatty acids + lysolecithin
128
What is more polar undigested lipids or digested lipids
Digested lipids
129
Where do digested lipids then enter
Micelles of bile salts
130
Digestion of triglycerides releases what What happens to the products
fatty acids and monoglycerides Assoicate with micelles of bile salts, then secreted by liver
131
What are chylomicrons
Resynthesize triglycerides and phospholipids, cholesterol combine with protein
132
Where do free fatty acids and monoglycerides go after they leave micelles
SI cells
133
By what process are chylomicrons secreted by
exocytosis into lymphatic vessels, then into blood
134
What happens to Chylomicrons in the blood
Are modified to release triglycerides for energy, fat storage and cholesterol
135
Chylomicrons =
Triglycerides + protein
136
What is an ulcer
Erosion due to a failure of protective mechanisms in the stomach, esophagus, or duodenum

Bio 66 (22 decks)

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