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Patho Test 3 GI > Digestion - Mace > Flashcards

Digestion - Mace Flashcards

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1
Q

What are the accessory digestive organs?

A

Teeth, tongue, salivary glands, liver, gallbladder, pancreas

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2
Q

What’s the difference between accessory digestive organs and the GI Tract?

A

Accessory glands are called accessory because food does not pass through hem.

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3
Q

The GI tract consists of

A

Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anus

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4
Q

The boundary of the mucosa is?

A

Muscularis mucosa - this is the deepest layer of the mucosa.

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5
Q

The serosa is continuous with the?

A

Mesentary

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6
Q

What does the muscularis mucosa do? What does the mucularis externa do?

A

The muscularis mucosa is about assisting in glandular secretions, and it is part of the mucosa The muscularis externa is not part of the mucosa but its own layer, it consists of two layers - inner circular and outer longitudinal. This aids in churning, and peristalsis of food.

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7
Q

Name the layers of the GI tract

A

Mucosa —> submucosa —> muscularis externa —> serosa or adventitia.

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8
Q

Adventitia is in the?

A

Thorax, and also around the rectum and anus, covering of retroperitoneal parts in the abdomen.

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9
Q

Visceral peritoneum is located in? What is it made of?

A

Visceral peritoneum is made of serous membrane and is located in the abdominal cavity.

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10
Q

The enteric nervous system includes?

A

Submucosal nerve plexus Myenteric nerve plexus Can function independently of the CNS

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11
Q

What are 4 examples of the mesentary?

A

Greater momentum, mesentary proper, lesser omentum, mesocolon

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12
Q

The muscularis provides? What are the 2 different types of action that it performs.

A

Provides motility 1) peristalsis - wave of contraction, and relaxation, moves bolus of food from one place to another 2) Mixing=segmentation, started from the inner circular layer (establishes segmentation), mixing is continued inner circular layer contraction and then longitudinal layer also contracts. (Shortening and widening of the bolus of food).

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13
Q

What are the extrinsic salivary glands? What are they sensitive to? What are they influenced by?

A

Extrinsic salivary glands are parotid, sublingual, and submandibular glands. They are sensitive to touch, smell and tase, and can be influenced by the autonomic NS, PNS.

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14
Q

By volume the Partoid provides what % of our saliva? Submandibular?

A

Parotid provides about 25% Submandibular provides 65% Sublingual must provide 10% then.

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15
Q

What are intrinsic salivary glands? What are the 3 different ones.

A

These are salivary glands that secrete at a constant rate. They are single cells in the mucosal lining of the mouth. They consist of lingual, labial, buccal.

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16
Q

What type of secretion do the parotid glands create?

A

Clear, watery, serous fluid, rich in salivary amylase

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17
Q

What type of secretion do the submandibular glands make?

A

Some serous fluid with some mucus, more viscous than parotid secretion

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18
Q

What type of secretion do the sublingual glands produce?

A

Primarily thick, stringy mucus.

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19
Q

What are the three phases of deglutition? Which is voluntary vs involuntary?

A

Voluntary phase (voluntary)- bolus of food pushed by tongue against hard palate then moves towards the oropharynx Pharyngeal phase (involuntary) - as bolus moves into oropharynx the soft palate and uvula close off the nasopharynx, and the larynx elevates so that the epiglottis closes over laryngeal opening. Esophageal phase (involuntary) - Closure of the superior esophageal sphincter. Bolus moves down the esophagus via peristalsis. Bolus passes through the esophagus and enters the stomach. The inferior esophageal sphincter opens allowing the movement into the stomach.

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20
Q

What three layers of muscle does the stomach have?

A

Longitudinal layer, circular layer, oblique layer. Oblique layer is unique - allows it to twist

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21
Q

The gastric pits in the stomach are able to be evacuated by what muscle layer?

A

The muscularis mucosa

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22
Q

What are the deepest cells in the gastric pit? What is their function?

A

G - cells - Enteroendocrine cells that secrete gastric into the blood.

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23
Q

What do chief cells secrete?

A

Chief cells secrete pepsinogen. Pepsinogen turns into pepsin when it comes into contact with hydrochloric acid. They also secrete gastric lipase - this chops up lipids in the stomach but not a whole lot.

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24
Q

What do parietal cells secrete?

A

First it secretes intrinsic factor which isn’t utilized until the large intestine for vitamin b 12. They also secrete hydrochloric acid. And a lot of it. Takes stomach contents down to a pH of about 3.

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25
What do mucous neck cells do?
They secrete acidic fluid containing mucin. These help protect the gastric pit from damage from the hydrochloric acid that is being secreted by the parietal cells.
26
What do surface mucous cells secrete?
They secrete mucin - like most goblet cells - but it also secretes an alkaline fluid
27
What does mucin need to combine with to form mucous?
Water
28
Describe the cephalic phase of gastric function.
Initiated by the thought, smell, sight, or taste of food (or even sounds of food preparation) 1) This is sensed by the special senses receptors in the higher brain regions. 2) This causes an increase in nerve signals relayed from the cerebral cortex and hypothalamus to the medulla oblongata. 3) The medulla oblongata integrates input from the higher brain centers and then sends a motor output signal. 4) The motor output signal goes to the stomach 5) These signals tell the stomach to both increase force of contraction but also the release of secretions.
29
Describe the gastric phase of the gastric function.
This is initiated by the presence of food in the stomach. 1) The receptors in the stomach are baroreceptors in the stomach wall. These detect stretch from the food in the stomach. There are also chemoreceptors that detect protein or high pH in the stomach contents. 2) Next sensory input from the receptors sends nerve signals relayed to the medulla oblongata. 3) Now the medulla oblongata integrates the sensory input from the stomach. It senses that there needs to be more action in the stomach. 4) So the medulla oblongata then sends increased nerve signals to the stomach. This is done along the vagus nerve. 5) The nerve signals from the medulla oblongata go to the stomach and cause both an increase in the force of contraction and a release of secretions. This works in a positive feedback loop. In addition: the presence of food in the stomach causes the release of gastrin. The gastrin targets both the stomach to increase force of contraction and also causes the release of secretions (especially HCL) and also stimulates the contraction of the pyloric sphincter. This works as an independent positive feedback loop.
30
Describe the intestinal phase of the gastric function.
This is initiated by the presence of acidic chyme in the small intestine. 1) Receptors: there are chemoreceptors in the intestinal wall that detects acidic chyme or low pH in the stomach contents. 2) the presence of the acidic chyme or low pH causes decreased nerve signals to the medulla oblongata 3) the medulla oblongata then integrates the information and decreases its nerve signals relayed to the stomach. 4) Decreased nerve signals are relayed from the medulla oblongata to the stomach. The effect being that the stomach is stimulated to both decrease force of contraction and release of secretions. In addition. Not only can you have acidic chyme in the duodenum, you can also have fatty chyme. Fatty chyme in the duodenum causes the release of CCK. CCK will also decrease the force of contraction in the stomach. Also acidic chyme causes the release of secretin. Secretin then also inhibits the release of stomach secretions.
31
Pesinogen is produced by __________ and activated by \_\_\_\_\_\_
Pepsinogen is produced by the chief cells and activated by hydrochloric acid secreted by the parietal cells.
32
What is the plicae circularis? What is on top of them?
The plicae circularis are the circular folds of small intestine in the GI tract. They are part of the submucosa There are intestinal villi on top of the plicae circularis that are part of the mucosa.
33
What is the epithelial cell layer in the small intestine? What structure is located here as well?
The intestinal villi are composed of simple columnar epithelial cells. These have microvilli attached to them that helps absorb nutrients and increase surface area.
34
What are the different cells in the small intestine? (3)
Simple columnar epithelial cells Goblet cells - produce mucin Intestinal glands - unicellular and enteroendocrine cells
35
What are the two different intestinal glands in the small intestine and what do they secrete?
Unicellular gland cell - synthesizes enteropeptidase. Enteroendocrine cell - secretes hormones.
36
Where are the lacteals located in the small intestine? What is their function.
They are within the villi of the small intestine. They run with the blood vessels. They are responsible for absorbing the fats in the small intestine and they also help remove excess fluid from the villi themselves.
37
What are Brunner’s glands? What do they secrete?
They are specialized mucous-secreting glands that secrete a thick, alkaline mucus in response to certain stimuli Stimuli - low pH coming from the stomach.
38
What are the enzymes in the microvilli?
These are known as brush border enzymes and they are the following Peptidase - breaks down peptides into amino acids Sucrose, Maltase, lactase - break down disaccharides into monosaccharides. Lipase - breaks down fats into fatty acids and glycerol.
39
What are the hormones secreted by the small intestine? (4)
Enterokinase - converts trypsinogen to trypsin Somatostatin - inhibits acid secretion by the stomach Cholecystokinin - inhibits gastric glands, stimulates the pancreas to release enzymes in the pancreatic juice, stimulates the gallbladder to release bile. Secretin - stimulates the pancreas to release bicarbonate ions in the pancreatic juice.
40
Monosaccharides are absorbed via what mechanism? What is their means of transport?
Mech: facilitated diffusion and active transport. Transport: blood in the capillaries
41
Amino acids are absorbed in the SI by what mechanism and what means of transport?
Mechanism: active transport Transport: blood in capillaries.
42
Fatty acids and glycerol are absorbed by what mechanism and what is their means of transport?
Mech: facilitated diffusion of glycerol; diffusion of fatty acids into the cells. A) most fatty acids are resynthesized into fats and incorporated in chylomicrons for transport — Mean of transport: lymph in lacteals B) some fatty acids with relatively short carbon chains are transported without being changed back into fats. — Mean of transport: blood in capillaries.
43
Electrolytes are absorbed by what mechanism and what’s their means of transport?
MOA: absorbed by diffusion and active transport depending on size and charge Transport: blood in capillaries
44
Water is absorbed by what mechanism and what is its mean of transport?
Mech: osmosis Means of transport: blood in capillaries.
45
What are the two main hormones that are responsible for regulation of secretion of the liver/gallbladder/pancreas?
CCK and Secretin
46
CCK is secreted by what cell? What causes its release? What is its action?
CCK is secreted by the enteroendocrine cells in the SI. It is secreted in response to fats in the duodenum or presence of proteins/aa Action: inhibit stomach activity(motility and secretion), gallbladder release bile, pancreatic acini release digestive enzymes, hepato-pancreatic sphincter opens.
47
Secretin is released by what cells? What is its stimulus to be release? What actions does it have?
Secretin is released by the enteroendocrine cells of the SI. Stimulus is when low pH of the stomach contents enters the SI. Action - inhibit stomach activity(motility and secretion), liver and pancreatic ducts release bicarbonate, and the hepato-pancreatic sphincter opens.
48
What is the function of the falciform ligament? what does it continue as inferiorly?
This is a fold of the peritoneum connecting the liver to the diaphragm. It continues as the round ligament that orignates from the umbical vein.
49
What is the digestive function of the liver?
Produce bile for emulsification, absorption of lipids, hydrophobic waste excretion.
50
Metabolism of carbohydrates, proteins, lipids, storage, synthesis of blood proteins/cholesterol, and detoxification is the general function of?
The liver
51
Which lobe is superior, cuadate or quadrate?
Caudate C before Q
52
Left and right hepatic ducts merge to form a
Common hepatic duct
53
Common hepatic duct and cystic duct merge to form a
common bile duct
54
The main pancreatic duct merges with the common bile duct at the
hepatopancreatic ampulla, which extends into the duodenum.
55
What duct allows pancreatic juices to continue to flow even if there is a blockage?
Accessory pancreatic duct.
56
What is the structure of the gallbladder?
3 Tunics of mucosa, muscularis, serosa.
57
What is the bile pathway starting at the bile canaliculi
Bile caniculi - bile ductules - hepatic ducts (right left) - common hepatic duct - common bile duct.
58
If bile is not used it backs up into the?
Backs up into the cystic duct and into the gallbladder
59
Function of the gallbladder?
Storage and concentration of bile
60
Function of bile?
Emulsification - increases surface area of fat.
61
98% of the tissue built in the pancreas is? What is the 2%?
98% of tissue built of acini - exocrine secretion of digestive enzymes 2% of tissue built by islet cells, endocrine secretion of insulin and glucagon.
62
Alpha cells produce? Beta cells produce? Where are they located?
Alpha = glucagon Beta = insulin located in pancreatic islet.
63
Acinar cells in the pancreas produce?
Amylase, lipase, protease, nuclease.
64
Duct cells in the pancreas and liver are responsible for producing?
HC03 (bicarb)
65
Describe the regulatin of pancreatic secretion in 4 steps
1) acidic chyme enters the duodenum 2) intestinal mucosa release secretin into bloodstream 3) secretin stimluates the pancreas to secete bicarbonate ions 4) pancreatic juice rich in bicarbonate ions passes down pancreatic ducts to the duodenum.
66
What stimulates the pancreas to release pancreatic juice high in bicarb ions? What about what stimulates it to release pancreatic juice high in enzymes?
Bicarb - secretin digestive enzymes - cck
67
Why are several digestive enzymes secreted as zymogens?
So they only act in the alimentary tract
68
What is the site of contact digestion? A) gastric pits B) Surface of gastric mucosa C) intestinal crypts D) Brush border of the small intestine E) Cytoplasm in the cells of the small intestine
Brush border of the small intestine (D)
69
Which of the following enzymes function at the lowest pH
Pepsin
70
What is the function of the large intestine? (3)
Absorption - water and electrolytes, indirectly vitamin B's and K Compaction - Storage
71
Are there any plicae or villi in the large intestine?
NO
72
Where are there high numbers of goblet cells, intestinal glands, and lymph nodules?
Large intestine
73
Where are there intestinal glands, lymph nodules, and teniae coli?
Large intestine
74
What are the the two types of motility in the large intestine?
Haustral contraction - uncoordinated contractions every 25 minutes Mass movement - 3-4 waves/daily based on gastrocolic reflex (when you eat) and duodenal colic reflex.
75
There is a significant amount of what type of cells in the large intestine?
goblet cells
76
What is the longitudinal muscular layer in the large intestine?
Transforms into the tenia coli
77
Internal anal sphincter is ________ and external anal sphincter is \_\_\_\_\_\_\_
Internal is involuntary - smooth External is voluntary - skeletal
78
Stretch in the rectum induces what reflex?
Defecation reflex
79
Describe the process of elimination in 5 steps
1) rectum content stimulates baroreceptors in the rectal wall. 2) Sensory input inititated by the baroreceptors in the rectum is relayed to the S.C. 3) Motor output in the parasympathetic axon is altered 4) Increased motor output to smooth muscle of the rectum; rectum contracts, squeezing the contents out. Decreased motor output to internal sphincter causes relaxation of the sphincter. 5) Somatic motor axons, concious decision to defecate is controlled by cerebral cx. External anal sphincter relaxes and valsalva maneuever is initiated, eliminating the feces.
80
Carbohydrate digestion occurs where?
In the oral cavity and in the small intestine.
81
Salivary amylase and pancreatic amylase are responsible for breaking down?
Disaccharides
82
Brush border enzymes use disaccharidases and create?
Monosaccharides
83
Absorption of carbohydrates occurs where?
Small intestine - jejunum and ileum via epithelial lining to blood capillaries in the vilil to the hepatic portal system.
84
Carbohydrates are converted to/stored as?
Glycogen and fats/triglycerides.
85
We use carbohydrates for?
Energy storage ATP production Structural components Markers as oligosaccharides
86
What 3 brush border enzymes break down carbohydrates?
Dextrinase Glucoamylase Maltase Convert oligosacchardies, maltose, and glucose into glucose molecules
87
Why is starch partially digested?
Spends little time in the mouth - has to wait for pancreatic amylase to act on it.
88
Describe the protein digestion in 4 steps
1) proteolytic enzymes are released from pancreas 2) enteropeptidase activates trypsinogen to trypsin; Trypsin then activates other proteolytic enzymes. 3) Activated pancreatic proteolytic enzymes break down proteins into peptides and amino acids 4) Brush border peptidases break peptides into single aa's to be absorbed through epithelia into the blood.
89
Describe lipid digestion/absorption after lingual and gastric lipases in 4 steps.
1) bile salts from the liver and gallbladder emulsify lipid droplets forming micelles. 2) Since surface area is increased, they are now acted upon by pancreatic lipase. Converts triglyceride to monoglyceride and free fatty acids (FFA's) 3) Monoglycerides and FFA's enter the epithelia, while bile salts remain int he intestinal lumen to be reabsorbed and recycled. 4) Monoglycerides and FFA's are packaged into vesicles and become chylomyrons and enter the lacteals
90
What is the function of the liver in carbohydrate metabolism?
1)Takes monosacchardies like glucose, fructose, galactose and converts them to glucose. Can store glucose as glycogen (glycogenesis) or release it into the blood stream (glycogenolysis) 2) Noncarbohydrates are converted to glucose by gluconeogenesis (glycerol and aa)
91
What does the liver do to proteins?
1) Deamination: amine group removed from amino acids - NH2 converted to urea and urea enters the blood (eliminated by kidney), 2) Amino acid used to form proteins, including plasma proteins 3) Transamination: Amino acids converted from one form to another
92
What does the liver do to lipids? 5 things.
1) Joins fatty acids together with glycerol to form triglycerides (lipogenesis) 2) Can release fatty acids from triglycerides (lipolysis) 3) Fatty acids can be broken down into acetyl CoA - beta oxidation 4) Acetyl Co-A can be converted to ketone bodies - oxidized in cellular respiration pathways 5) Acetyl Co-A used in cholesterol synthesis; cholesterol released into blood within VLDLs, and some used to form bile salts and released as a component of bile.
93
How are Nucleic acids digested?
Nucleases - pancreatic - form nucleotides Phosphatases and nucleosidases (Brush border) break down nucleotides to N-base, **ribose, and phosphate** that can be absorbed into blood capillaries.
94

Patho Test 3 GI (2 decks)

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