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Mam Physiology > GI > Flashcards

GI Flashcards

1
Q

Primary purpose of digestive tract

A 
Primary purpose
– Transfer nutrients
from ingested food
into body’s internal
environment
– Ingested food is
essential as an
energy source and
as the building
blocks of tissues
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2
Q

schematic pathway through GI

A

Oral cavity -> esophagus->
stomach -> small intestine ->
large intestine -> rectum

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3
Q

What is the statement concerning the amount of liquid entering and leaving Gi

A

The volume of fluid entering the GI tract must equal

the volume leaving

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4
Q

4 major functions of GI

A 
1. Motility- muscular
contractions that mix
food and move it
forward
2. Secretion- of
digestive juices
3. Digestion-
Biochemical
breakdown of
complex food stuffs
4. Absorption –of small
absorbable units and
water
5. Excretion-elimination
of feces
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5
Q

2 types of motility in GI

A 
Peristaltic contractions ( propulsion)
Segmentation contractions : mixing
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6
Q

What is the general composition of digestive secretions

A 
– Water, electrolytes, and
specific organic
constituents (enzymes)
– Secretions are released
into digestive tract lumen
on appropriate neural or
hormonal stimulation
– Normally reabsorbed in
one form or another back
into blood after their
participation in digestion
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7
Q

What is digestion

A

the biochemical breakdown of
structurally complex foodstuffs into smaller,
absorbable units
– Accomplished by enzymatic hydrolysis

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8
Q

What is enzymatic hydrolysis

A

adding water at the bond site
allows enzymes in the digestive secretions to break
down the bonds that hold the smaller molecular
subunits within the nutrients.

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9
Q

Absorbable units of macronutrients

A
  • Carbohydrates → monosaccharides
  • Proteins → amino acids
  • Fats → glycerol and fatty acids
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10
Q

Parts of stomach

A

– (cardia)->Fundus ->body -> pyloric antrum

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11
Q

what are the parts of the rest of GI after the stomach (also valves)

A 
Pyloric valve
• Small intestine
– Duodenum à jejunum à ileum
• Accessory organs: pancreas and liver
• Large intestine: colon and rectum
• Anus
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12
Q

4 general tissue layers in GI

A
  1. Mucosa
  2. Submucosa, connective tissue and glands
  3. Muscularis externa
  4. Serosa
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13
Q

Describe mucosa layer in GI

A

Innermost layer, epithelium, connective

tissue, muscle

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14
Q

Describe muscularis externa in GI

A

inner layer of
circular outer of longitudinal, nerves
organized into a plexus-regulate
movement, mechanical breakdown

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15
Q

What is serosa in GI

A

Outer layer, connective tissue, fold

connect to form mesentry

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16
Q

Three layers in mucosa

A

Mucous elithelium
Lamina propria
Muscularis mucosae

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17
Q

2 types of muscular layer in muscularis externa

A

Circular and on top longitudinal

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18
Q

Serosa role

A

To prevent friction between other organs

Anchoring everything in place to prevent twisting

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19
Q

3 major pairs of salivary glands

A

Parotid gland
Submandibular gland
Sublingual gland

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20
Q

Composition of saliva

A

• 99.5% H2O
• 0.5% electrolytes and protein
(amylase, mucus, lysozyme)

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21
Q

Salivary gland composition

A

Serous cells are specialized to secrete an enzyme solution
Mucous cells

and then duct is lined with duct epithelium

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22
Q

Functions of saliva

A 
• Salivary amylase begins digestion of
carbohydrates (1 hour then
deactivated)
• lingual lipase (activated in stomach)
• Facilitates swallowing by moistening
food
• Mucus provides lubrication
• Antibacterial action
– Lysozyme destroys bacteria
– Saliva rinses away material that could
serve as food source for bacteria
• Rich in bicarbonate buffers (amylase
works best at slightly basic pH)
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23
Q

In what layer lymphoid nodules are found in GI

A

In lamina propria (mucosa)

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24
Q

What cells line the esophagus and what layers

A 
Lined with stratified squamous
epithelium (has same four layers
as entire digestive tract)
1.Mucosa
2.Submucosa, connective tissue and glands
3.Muscularis externa
4.Serosa
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25
Q

Esophagus extends between ___

A

pharynx and

stomach

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26
Q

How food is pushed through esophagus

A

Peristaltic waves push food through esophagus

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27
Q

What sphincters esophagus has at each end

A

Pharyngoesophageal sphincter
– Keeps entrance closed to prevent
large volumes of air from entering
esophagus and stomach

– Gastroesophageal (cardiac)
sphincter
– Prevents reflux of gastric contents

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28
Q

Outter serosa in esophagus has another name and it is ___

A

Adventitia

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29
Q

Stomach is

A

J-shaped sac-like chamber lying between

esophagus and small intestine

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30
Q

3 main functions of stomach

A
  1. Store ingested food until it can be emptied into
    small intestine
  2. Secretes hydrochloric acid (HCl) and enzymes
    that begin protein digestion(pepsin)
  3. Mixing movements convert pulverized food to
    chyme
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31
Q

2 curvatures of the stomach and where do they attach to

A

Lesser curvature to organs behind the stomach

Greater curvature to the large intestine

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32
Q

Folds in stomach are called

A

Rugae

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33
Q

What glands are found in the mucosa of the stomach and what they secrete

A 
Secretory cells: mucous,
chief (enzymes), parietal (HCl
and intrinsic factor) and
endocrine (ghrelin hormone
that regulates appetite)
• Gastric pits and
• Glands secrete most of the
gastric juice-mucous fluid
containing digestive enzymes
and HCl
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34
Q

What does inner epithelial layer contains and what does it secrete and serves as

A 
• Serves as protective surface
• Modified for secretion and
absorption
• Contains
– Exocrine gland cells – secrete
digestive juices
– Endocrine gland cells (secretes
into blood or tissue) – secrete
blood-borne gastrointestinal
hormones
– Epithelial cells – specialized for
absorbing digestive nutrients
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35
Q

What is lamina propria, what does it have

A 
Lamina propria-thin layer of
connective tissue
• Houses gut-associated lymphoid
tissue (GALT)
– Important in defense against
disease-causing intestinal
bacteria (at the base of each crypt there are cells secreting bactericidal enzymes)
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36
Q

what type of muscles is in muscularis mucosa

A

Smooth muscle

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37
Q

Rugae is marked by ___

A

depressions

called gastric pits

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38
Q

We have villi only in

A

Small intestine

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39
Q

Submucosa role and what is it

A 
Thick layer of
connective tissue
• Provides
digestive tract
with distensibility
and elasticity
• Contains larger
blood and lymph
vessels
• Contains nerve
network known
as submucosal
plexus (imp for
exocrine function
and contraction
of muscles)
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40
Q

Difference between circular and longitudinal muscles

A 
Circular layer
• Inner layer
• Contraction
decreases
diameter of lumen
– Longitudinal layer
• Outer layer
• Contraction
shortens the tube
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41
Q

What is mesenterius

A

Double sheets of serous membranes composed
of parietal and visceral peritoneum
- Stabilize the positions of some organs
- Prevent intestines from getting tangled during
digestion
- Provide a pathway for blood vessels, nerves,
and lymphatic vessels servicing the digestive
tract

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42
Q

Digestive motility and secretion are regulated by

A

– Autonomous smooth muscle function

– Gastrointestinal hormones

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43
Q

4 aspects in gastric motility and characteristics of each

A

– Filling
• Involves muscular relaxation
– Enhances stomach’s ability to accommodate the extra
volume of food with little rise in stomach pressure
– Triggered by act of eating
– Storage
• Takes place in body of stomach
– Mixing
• Takes place in antrum of stomach
– Emptying
• Largely controlled by factors in duodenum

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44
Q

Mixing
actions in the stomach
include both

A

propulsion

and retropulsion

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45
Q

____ is main factor that influences

strength of contraction

A

Amount of chyme in stomach

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46
Q

In what state the food should be before moving to small intestine

A

Liquid

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47
Q

How duodenum and stomach regulate the emptying of chyme to SI on the example of fat

A

Fat is digested and absorbed more slowly than other
nutrients
• Fat digestion and absorption takes place only within lumen of
small intestine
• When fat is already in duodenum, further gastric emptying of
additional fatty stomach contents is prevented until the
existing fat is completely processed
• For ex a high fat meal may take 6 hours to empty whereas a
lean meat and potatoes meal may take only 3 hours

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48
Q

How duodenum and stomach regulate the emptying of chyme to SI on the example of acid

A

The stomach secretes HCl and highly acidic chyme is
neutralized in the duodenum by sodium bicarbonate
(secreted by the pancreas)
• Unneutralized acid in duodenum inhibits further emptying of
acidic gastric contents until neutralization can be
accomplished

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49
Q

How duodenum and stomach regulate the emptying of chyme to SI on the example of hypertonicity

A

build up of amino acids and glucose
molecules slows gastric emptying. When osmolarity
of duodenal contents starts to rise closure to stomach.

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50
Q

How duodenum and stomach regulate the emptying of chyme to SI on the example of distension

A

Too much chyme in duodenum inhibits emptying of even

more gastric contents

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51
Q

Factors Controlling Gastric Emptying

A

One of the Factors (fat, hypertonicity, acid, distension) trigger either
1. A Neural response
• Collectively called enterogastric reflex acts to slow the peristaltic
activity – smooth muscle contractions-autonomic system
OR
2. Hormonal response
• Release of GIP (gastric inhibitory peptide), endocrine hormone that
acts on gastric muscle to decrease peristalsis and thus slow
passage of food into the duodenum
• Additional factors that that influence gastric motility
– Emotions
• Sadness and fear – tend to decrease motility
• Anger and aggression – tend to increase motility
– Intense pain – tends to inhibit motility

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52
Q

Two distinct areas of gastric
mucosa that secrete gastric
juice

A

– Oxyntic mucosa
• Lines body and fundus
– Pyloric gland area (PGA)
• Lines the antrum

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53
Q

Gastric juice : content

A

(strongly acidic
secretion from glands,
enzymes ex pepsin, intrinsic
factor, mucus, water)

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54
Q

Three phases of gastric secretion:

A

Cephalic phase
Gastric phase
Intestinal phase

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55
Q

What is cephalic phase

A

Sensation or thought
about food are relayed to the brainstem (medulla). In response
parasympathetic signals to the gastric mucosa are
initiated. Stimulates secretion of gastric juice.

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56
Q

What is gastric phase of juice secretions

A

The distension of the stomach caused by the presence of food
triggers local and parasympathetic reflexes that increase secretion
of gastric juice. Gastrin (secreted by endocrine G cells) is a
digestive hormone secreted by mucosa in presence of food causes
increased secretion of gastric juice.

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57
Q

What is Intestinal phase

A

Triggers endocrine response

Once food enters the SI, stomach activity is inhibited by decreased gastric
juice secretion initiated by GIP (gastric inhibitory peptide), CCK and secretin
–opposes gastric juice secretion. Opposes action of gastrin. Stimulates
ejection of bile from the pancreas required for neutralization of HCl in the
duodenum

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58
Q

Two type of secretory tissues in the stomach

A 
Oxyntic mucosa ( the upper layer)
Pyloric gland area ( near the pyloric sphincter)
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59
Q

In what layer gastric pits are found

A

Mucosa

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60
Q

What cells oxyntic layer has

A

Contains contains gastric glands which have endocrine, chief, parietal, ECL (enterochomaffin-like) cells

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61
Q

What connects gastric gland with the surface of the stomach and what is found there

A

Gastric pit, with mucosa cells

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62
Q

Mucous cells: role and type of gland

A

Exocrine
secrete mucus,
protects epithelial cells in the stomach against pepsin and acid

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63
Q

Chief cells: role and type of gland

A

exocrine
release pepsinogen and chymosin

pepsinogen when
activated begins protein digestion

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64
Q

Parietal cells: role and type of gland

A

Exocrine

HCl, activates
pepsinogen, denatures proteins,
breaks down connective tissue,
kills microorganisms, intrinsic
factor imp for vitamin B12
absorption
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65
Q

ECL: role and type of cell

A

Exocrine neuroendocrine

Release histamine that stimulates parietal cells

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66
Q

Pyloric gland area has what type of cells

A

contain mucous

cells and G cells, D cells

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67
Q

Role of g cells and what type of cells

A

Endocrine
G-cells secrete gastrin which stimulates
exocrine cells- to secrete greater gastric
juice which has high HCl and pesinogen.

Mechanism to ensure that when there is
food in the stomach there will be enough
juice and enzymes there to digest it.
promotes digestion

68
Q

D cells : role and type of cell

A

Endocrine

D cells produce the only inhibitiry
secretions-somatostatin
• Acts to inhibits parietal cells (HCl), G
cells (gastrin which increases digestive
juice secretion) and ECl cells.
69
Q

difference between endocrine and exocrine glands

A

Endocrine: ductless glands
that secrete hormones
• Exocrine-secrete through
ducts into a cavity

70
Q

Role of HCl

A 
Activates pepsinogen to
active enzyme pepsin
and provides acid
medium for optimal
pepsin activity
– Aids in breakdown of
connective tissue and
muscle fibers
– Denatures protein
– Along with salivary
lysozyme, kills most of
the microorganisms
ingested with food
71
Q

How HCl gets produced in gastric parietal cells

A

H-K pump on the apical surface of parietal cells pumps K in and H+ out. NOTE: H+ is coming from carbonic acid, a combination of CO2 and H2O in parietal cells. It is unstable , so it breaks down to HCO3- and H+. HCO3- goes out of the cells to the capillary through chloride shift and this Cl- from blood can get inside parietal cells

Chloride ions are pumped into the lumen of the stomach, where it reacts with H+

72
Q

The gastric mucosal barrier made up of the following components enables the stomach to contain acid without injuring itself:

A

1) The luminal membranes of the gastric mucosal cells are impermeable to H+ so that HCl cannot penetrate into the cells
2) The cells are joined by tight junctions that prevent HCl from penetrating between them
3) A mucus coating over the gastric mucosa offers further protection

73
Q

What happens when the gastric mucosal barrier is damaged

A

Gastric ulcers

74
Q

What is the cause of 60% of ulcers

A

Helicobacter pylori

75
Q

How H.pylori survives the acid in the stomach

A

H pylori has a unique, acid gated membrane channel, which effectively controls the amount of alkali produced by the bacterium to combat gastric acid, allowing it to survive and grow in gastric acid.

76
Q

Where usually you can find H.pylori in the stomach

A

In Fundus where there is less acid

It uses flagella to burrow itself below mucus cells

77
Q

How H.pylori causes ulcers

A

Damage mucus barrier and
tight junction
• Allows HCl to damage
intestinal tissue

78
Q

H.pylori is treated with

A

Antibiotics

79
Q

What is the other cause of ulcers apart form H.pylori

A

emotion/stress can increase

gastric juice secretion

80
Q

What is the way to treat ulcers if not concentrating on bacteria

A

By PPI (Proton pump inhibitors) to prevent HCl formation

81
Q

Examples of PPI

A

omeprazole, Lansoprazole

82
Q

Action of PPI

A

It can act at different levels: inhibit H/K ATPase, so no Hydrogen pumped into the stomach

83
Q

What is GERD and what is the treatment

A

When lower esophageal sphincter fails to stay closed and stomach acid damages the lining of the esophagus

Treated with PPIs

84
Q

Ulcers can be from ____

A

the
overuse of NSAIDs (a drug class that reduce pain, decrease fever, prevent blood clots and, in higher doses, decrease inflammation) or H.
Pylori or stress/emotions

85
Q

Pancreas is

A

Mixture of exocrine and endocrine tissue
• Elongated gland located behind and below the
stomach

86
Q

Endocrine function of pancreas

A 
performed by Islets of Langerhans
• Found throughout pancreas
• Secrete insulin (Beta cells-causes uptake of
glucose) and glucagon (released when low
glucose)
87
Q

Exocrine function of pancreas

A 
Secretes pancreatic juice consisting of
• Pancreatic enzymes (Trypsinogen,
lipases, nucleases) actively secreted by
acinar cells
• Aqueous alkaline solution actively secreted
by duct cells that line pancreatic ductsimportant
for neutralizing stomach contents
in duodenum
88
Q

What cells secrete pancreatic enzymes

A

Acinar

89
Q

exocrine secretion of pancreas are regulated by

A

Secretin-(from intestinal mucosa)
– CCK-Cholecystokinin (from intestinal mucosa)
– Both act to stimulate release of pancreatic juice

90
Q

What are proteolytic enzymes in pancreas

A

Trypsinogen - converted to active form trypsin (converting
enzymes sits poised on mucosal epithelium)
• Chymotrypsinogen – converted to active form chymotrysin

91
Q

Action of pancreatic amylase

A

Converts polysaccharides into the disaccharide amylase

92
Q

What is particular about pancreatic lipase

A

Only enzyme secreted throughout entire digestive system that

can digest fat

93
Q

What cells secrete NaHCO3 in pancreas

A

Duct cells

94
Q

What is proteose

A

a water-soluble compound produced during

digestion by hydrolytic breakdown of proteins

95
Q

Protein is broken down to peptides and proteoses by proteases in gastric and pancreatic juices.

What is going to break down peptides and proteoses to amino acids

A

peptides:intestinal peptidases
Proteoses: proteases in pancreatic juices

96
Q

Is pepsinogen active?

A

No, pepsin is active

97
Q

How liver is important to digestion

A

secretion of bile

salts which are important for fat digestion

98
Q

What is the largest gland in the body

A

Liver

99
Q

Anatomy of liver

A

Consists of two lobes which are highly vascularized

100
Q

Liver functions

A

detoxification

  • bile secretion
  • stores iron, vit D, A B12
  • site of hematopoiesis during fetal development
101
Q

Right and left lobe of the liver is separated by

A

Round ligament

102
Q

All the nutrients from the intestine are going to the liver by

A

Hepatic portal vein

103
Q

Functional unit of liver is

A

Liver acinus

104
Q

Liver acinus has the form of ___, and each end has ___

A

Hexagon

Hepatic triad: hepatic portal vein, hepatic artery and bile ductule

105
Q

Functions of liver

A

Synthesis and secretion of bile

Storage of glycogen and lipid reserves

Maintenance of normal blood levels of glucose, AAs and FAs

Synthesis and interconversion of nutrient types

Synthesis and release of cholesterol bound to transport proteins

Inactivation of toxins, lipid-soluble drugs

Storage of iron reserves

Storage of fat-soluble vitamins

Absorption and breakdown of circulating hormones (insulin, epinephrine) and immunoglobins

106
Q

How liver and gall bladder is connected to intestine

A

ducts from the liver that carry the bile to be ejected into the
duodenum
• The hepatic ducts fuse with the gallbladder cystic duct, to
form the common bile duct that enters into the duodenum

107
Q

Where bile is stored between meals

A

Stored and concentrated in gallbladder

108
Q

What are lecithins, where they are produced and what is their function

A

Derivatives of cholesterol
– Convert large fat globules into a liquid emulsion
– After participation in fat digestion and absorption,
most are reabsorbed into the blood

109
Q

Blood flow through liver

A

From intestine - hepatic portal vein
From the heart: hepatic artery

From liver to inferior vena cava-hepatic vein

110
Q

What nutrients are stored in the liver

A

Glucagon

Fat-soluble vitamins A, D, E, and K

111
Q

How liver monitors and adjust circulating nutrients

A

High blood glucose triggers synthesis of glycogen
• Low blood glucose triggers breakdown of glycogen and
release of glucose

112
Q

What is the function of Phagocytic Kupffer cells in the liver

A

remove old or damaged

RBCs, debris, and pathogens from blood

113
Q

What is the function of plasma proteins secreted by liver

A

Determine osmotic pressure of plasma
– Function as nutrient transporters
– Key elements of clotting and complement cascades

114
Q

What is NAFLD

A

The most frequent form of fatty liver disease
– namely the non-alcoholic fatty liver disease
(NAFLD)
– form of chronic liver disease, resembling the
histological changes of alcoholic liver disease
– found in subjects who do not abuse alcohol
– Is tightly-linked with type II DM
– prevalence of NAFLD is growing worldwide due
to the increasing prevalence of obesity, diabetes
and the metabolic syndrome.

115
Q

What is NASH and how it is identified

A

Non Alcoholic Steatohepatitis (NASH)

Identified by
abnormal lipid
accumulation and
presence of
inflammatory cells
116
Q

NAFLD progression

A

Healthy liver->NAFLD->NASH
This steps are reversible

From NASH to cirrhosis is irreversible

117
Q

What is steatosis

A

comprises abnormal accumulation of triglycerides in

hepatocytes in response to metabolic, toxic, and viral conditions

118
Q

What is the normal thing about liver and aging

A

Macrovesicular steatosis

119
Q

A progression of macrovesicular steatosis is

A

Microvesicular

120
Q

What is cirrhosis

A 
chronic or scarred liver as a
result of chronic inflammation due to
hepatits, chemicals that destroy
hepatocytes, parasites that infect the liver,
or alcoholism
121
Q

What is hepatitis

A

inflammation of the liver caused

by viruses, drugs, and chemicals

122
Q

Hepatitis A: cause, symptoms and effect

A 
spread by fecal
contamination of objects (food, clothing,
toys, eating utensils: fecal-oral route)
- Loss of appetite, malaise, diarrhea,
nausea, fever, chills
- Does not cause lasting liver damage
123
Q

Hepatitis B: cause, symptoms and effect

A

spread primarily through
sexual contact and contaminated syringes
and transfusion equipment; also via saliva
and tears (bodily fluids)
- Can produce cirrhosis and possible liver
cancer
- Can be carriers

124
Q

Hepatitis C is similar to

A

Hepatitis B

125
Q

Common bile duct and pancreatic duct are both controlled by

A

Hepatopancreatic sphincter

126
Q

Where gallbladder is found

A

the posterior surface of the

liver’s right lobe

127
Q

Functions of the gallbladder

A

Stores bile
– Releases bile into duodenum, but only under
stimulation of hormone cholecystokinin (CCK

128
Q

How much bile there can be in gallbladder and what is happening with it over time

A 
Full gallbladder contains 40–70 mL bile
– Bile composition gradually changes in
gallbladder:
• Water is absorbed
• Bile salts and solutes become concentrated
129
Q

Where most digestion and absorption of food happens and what is done to make it more efficient

A

Small intestine
Surface area increased by circular folds, villi, and
microvilli

130
Q

The end of small intestine is

A

ileocecal valve

131
Q

Functions of small intestine

A

Segmentations mix chyme with digestive juices
and bring food to mucosa for absorption; peristalsis
2. Completes the digestion of carbohydrates,
proteins, and lipids; begins and completes
digestion of nucleic acids
3. Absorbs ~90% of nutrients (including water) that
pass through the digestive system

132
Q

What is folds of mucosa

and submucosa

A

Circular folds (plicae circulares):

133
Q

What is villi and microvilli

A

Villi: fingerlike projections of mucosa; increase SA

- Microvilli: projections of the apical membrane of the
absorptive cells (villi)
134
Q

Structure of villi

A
  • Each is covered by epithelium with a core of
    lamina propria with an arteriole, a venule, a
    capillary network, and a lacteal embedded)
135
Q

3 parts of small intestine

A 
Duodenum-the uppermost
(shortest)portion and is the
part to which the pyloric end
of the stomach attaches
– Jejunum- commences at point
where the tube turns
downwards
– Ileum –(longest) last segment
with no clear demarcation
136
Q

2 types of digestive motility and their function

A

Propulsive (peristaltic) movements
– Push contents forward through the digestive tract

• Mixing movements (segmentation)
– Serve two functions
» Mixing food with digestive juices promotes digestion
of foods
» Facilitates absorption by exposing all parts of
intestinal contents to absorbing surfaces of digestive
tract

137
Q

Segmentation movements

A

ringlike contractions

138
Q

Segmentation is initiated by

A

pacemaker cells in small intestine

which produce basic electrical rhythm (BER)

139
Q

Circular smooth muscle responsiveness is initiated by

A

distension of intestine, gastrin, and

extrinsic nerve activity

140
Q

What is migrating motility complex

A

a cyclic, recurring motility pattern that occurs in the stomach and small bowel during fasting; it is interrupted by feeding.

Sweeps intestines clean between meals

141
Q

Who is doing the work of digestion in small intestine

A

Juice secreted by small intestine does not contain
any digestive enzymes
• Digestion
– Pancreatic enzymes continue carbohydrate and
protein
– Brush-border enzymes complete digestion of
carbohydrates and protein
– Fat is digested entirely within small intestine
lumen by pancreatic lipase

142
Q

Most of absorption happens in

A

duodenum and jejunum

143
Q

Lining of small intestine is changed every __

A

3 days

144
Q

How TGs undergo hydrolysis and absorption

A 
Triglycerides are
subsequently broken into
monoglycerides and longand
short-chain fatty acids
• Short-chain fatty acids can
often be absorbed
• Bile salts surround longchain
fatty acids and
monoglycerides forming
tiny spheres called
micelles
• Then undergo hydrolysis
by pancreatic lipase
• Absorbed by brush border
145
Q

Where chylomicrons are assembled

A

Golgi in small intestine cells and then through lacteal into lymph

146
Q

Amylase function

A

breaks down starch, glycogen into disaccharides

147
Q

How proteins are absorbed

A

After digestion
Di and tripeptides cotransport paired with H+ via Na(in)-H(lumen)+( pump
Amino acids contransport with Na

Small peptides are carried intact across the cell by transcytosis-“ blood

148
Q

Parts of large intestine

A

– Colon
– Cecum
– Appendix
– Rectum

149
Q

Parts of colon

A

ascending colon, transverse colon,

descending colon, sigmoid colon

150
Q

Function of large intestine

A 
Reabsorption of water
– Reabsorption of bile salts
– Absorption of vitamins (vitamin K, pantothenic
acid B5, biotin) produced by bacteria
-Preparation of feces for excretion
151
Q

Difference between anatomy of large and small intestine

A

Has a larger diameter and thinner wall than small intestine
– The wall of the colon:
• Forms a series of pouches (haustra)

152
Q

What is haustra

A

Haustra permit expansion and elongation of colon

Muscle tone in taeniae coli creates the haustra

153
Q

What is taeniae coli

A

Three longitudinal bands of smooth muscle (taeniae coli):
• Run along outer surfaces of colon
• Deep to the serosa
• Similar to outer layer of muscularis externa

154
Q

Borders of ascending and transverse colon

A

Ascending Colon
– Begins at superior border of cecum
–
bends at right colic flexure (hepatic flexure)

• Transverse Colon
– Crosses abdomen from right to left; turns at left colic
flexure (splenic flexure)
– Is separated from anterior abdominal wall by greater
omentum

155
Q

Sigmoid colon starts ___

A

At sigmoid flexure

156
Q

When we start to have an urge to defecate

A

Movement of fecal material into rectum

157
Q

2 sphincters in anal

A

Internal anal sphincter:
• Has smooth muscle cells, not under voluntary control
– External anal sphincter:
• Encircles distal portion of anal canal
• A ring of skeletal muscle fibers, under voluntary control

158
Q

Histology of the large intestine

A

Lack villi or other structures that increase SA
– Abundance of mucous cells; mostly absorptive
and goblet cells

159
Q

when haustral churning occurs

A

Haustra remain relaxed and become distended
while they fill
- Distension reaches a certain point, walls contract
and squeeze contents into next haustrum
- Peristalsis occurs at a slower rate

160
Q

What is appendix

A

Vestigial organ: shrunken remainder of cecum
– Is dominated by lymphoid nodules (a lymphoid
organ

161
Q

What is appendicitis, cure, causes

A 
Inflammation of the appendix
• High mortality
• Requires immediate surgical removal
• Possible causes:
- Obstruction
- Low transit time
- Low dietary fiber intake
- (none are mutually exclusive)
162
Q

Gastrin: stimulus, origin, target and effects

A

Vagus nerve stimulation or arrival of food in the stomach (produced in stomach)

Arrival of chyme containing large quantities of undigested proteins ( produced in duodenum)

Target: stomach

Effects; stimulate production of acids and enzymes, increases motility

163
Q

Secretin: stimulus, origin, target and effects

A

Arrival of chyme in the duodenum

Produced in duodenum
Target: pancreas, stomach, liver

Effects: stimulates production of alkali buffers
inhibits gastric secretion and motility
Increases rate if bile secretion

164
Q

CCK: stimulus, origin, target and effects

A

Arrival of chyme containing lipids and partially digested proteins

Secreted in duodenum

Pancreas-stimulates production of pancreatic enzymes

Gallbladder: Stimulated contraction of gallbladder

Duodenum: causes relaxation of sphincter at base of bile duct

stomach-inhibits gastric secretion and motility

CNS-may reduce hunger

165
Q

Gastric inhibitory peptide: stimulus, origin, target and effects

A

Arrival of chyme containing large quantities of fats and glucose

ORIGIN: duodenum and stomach

Target: pancreas -stimulates release of insulin
In stomach -inhibits gastric secretion and motility

166
Q

What is the second leading cause if cancer mortality in Canada

A

Colon cancer

167
Q

potential causes of colon cancer

A

Incidence increased among persons with family history
• Also increases with persons with Crohn’s
disease, ulcerative colitis and those with
adenomatous polyposis (genetic: autosomal
dominant)
• Diet also plays a role
- Dietary fat intake (increases bile acid synthesis,
may be converted into carcinogens by bacterial
flora in colon)
- Refined sugar intake (enhances above)
- Fiber intake (increases stool bulk thereby diluting
and removing potential carcinogens)
- Adequacy of protective micronutrients such as
vitamins A,C, and E in diet (refined diets often
contain reduced amounts of A,C, and E which
may act as oxygen free radical scavengers

-Polips grow

Mam Physiology (16 decks)

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