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physiology 2 > GI > Flashcards

GI Flashcards

1
Q

food is required to the body for?

A

production of energy

repair of tissues

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2
Q

protein and carbs provide how many clas of energy to the body?

A

4 cal

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3
Q

lipids provide how many cals of energy?

A

9 cal

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4
Q

alcohol provide how many cals of energy?

A

7 cal

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5
Q

an average human being consumes how much solid food and liquid?

A

1 kg of food and 1-2 liters of fluid

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6
Q

women consume — cal per day

A

1.6-2.4 kcal

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7
Q

men consume how many cal per day?

A

2-3 kcal

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8
Q

what is the alimentary canal?

A

its a continues tube stretching from the mouth to anus

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9
Q

what is the function of the GI system?

A

ingestion

digestion

absorption

propulsive movement

secretion

host defense

elimination

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10
Q

what is propulsive movement?

A

its peristalsis movement which a food moves at a rate optimal for digestion and absorption

peristalsis moves the bolus forward

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11
Q

what type of secretion happen in the GI?

A

water

salt

electrolyte

digestive enzymes

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12
Q

what does elimination do in the GI?

A

it removes indigestible remains and hydrophobic substances

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13
Q

what is host defense?

A

means the GI system has its own immune system

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14
Q

what is the defense mechanism found in the oral cavity?

A

IgA and lysozyme

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15
Q

what is the immune tissue found in the stomach?

A

Hcl and pepsin which have bactericidal effect

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16
Q

what is the immune tissue found in the small intestine?

A

payers patch which is a lymphoid tissue that differentiate into B cells and T cells that produce anti bodies

major source of antibody production

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17
Q

GI in fluid balance

A

its responsible for fluid balance of circulatory system in systemic and any factor that affects the fluid balance of the GI has direct effect on disturbing the circulatory system

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18
Q

how much secretions in the GI lumen daily?

A

7 liters of fluid are secreted and 2 liters of water is drank daily

so 9 lit is added into GI daily

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19
Q

how much liquid is absorbed by the GI daily?

A

7.5 liters of water absorbed from the small intestine

1.4 from the large intestine

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20
Q

how much fluid is excreted by the GI daily?

A

only 50- 100 ml of fluid

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21
Q

list the functional layers of the GI

A

mucosal

submucosal

muscularis externa

serosa

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22
Q

what are the 3 layers of the mucosal layer?

A

epithelium

lamina propria

muscularis mucosae

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23
Q

the epithelium is made from

A

columnar or stratified squamous cells and it covers the lumen of the GI

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24
Q

the epithelium covers

A

fibrous in esophagus

and serous in most of GI tract

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25
Q

____have lots of foldings

A

mucosal layer

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26
Q

the lamina propria contains?

A

capillaries which are responsible for micro exchange for absorption

lymph nodules for immunological defense

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27
Q

the muscularies mucosae?

A

is a thin layer of smooth muscle which have 2 longitudinal and circular

it changes the degree of folding in lumen as it contracts and relaxes

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28
Q

the submucosa contains?

A

contains large blood vessels, glands and nerve fibers

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29
Q

the submucosa also have___ which control GI secretions

A

high neural plexus which control blood flow and GI secretions

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30
Q

whats the nerve plexus found in submucosa called?

A

messiners plexus or submucosa plexus

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31
Q

where is the messiners plexus located?

A

between sub mucosa and circular smooth muscles

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32
Q

what is muscularis externa ?

A

smooth muscle of the GI which contains circular and longitudinal layers

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33
Q

____ is found between the layer of the muscularis externa( longitudinal and circular)

A

myeinteric plexus

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34
Q

myeinteric plexus is responsible for?

A

to control motility of the GI

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35
Q

contraction of the circular muscles will…

A

decrease the lumen

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36
Q

contraction of the longitudinal muscles will…

A

decrease the length of the GI tract

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37
Q

what is the serosa?

A

its the outer layer which contains connective tissues which are fibro-serous covering

its a protective layer

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38
Q

what are the voluntary segments of the GI?

A

mouth, tongue, upper 1/3 of the esophagus and external anal sphincter

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39
Q

what are the involuntary segments of the GI?

A

GI smooth muscles which are visceral or unitary type of smooth muscles

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40
Q

what do GI smooth muscles exhibit?

A

they show functional syncytium meaning stimulation of the smooth muscles at one point will result in synchronous excitation

the individual cells work with adjacent cells for coordinated action. Rapid transmission of electrical impulses transfers between cells to trigger simultaneous contraction

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41
Q

GI functions are controlled by?

A

intrinsic mechanisms and extrinsic mechanisms

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42
Q

intrinsic mechanisms are?

A

enteric nerve system

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43
Q

extrinsic mechanisms are?

A

ANS and hormones

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44
Q

___is similar to the pacemaker cells of the heart

A

enteric nerve system

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45
Q

enteric nerve system is composed of?

A

messiners and myeinteric plexus

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46
Q

which ANS increase the GI function: sympathetic or parasympathetic?

A

parasympathetic

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47
Q

___is also known as the little brain of the GI and why?

A

enteric nerve system and its because it can act independently and control local reflexes

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48
Q

what are the 2 types of the GI motility?

A

segmentation and peristaltic movements

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49
Q

what is segmentation?

A

also known as mixing movement that occurs in the small intestine and it mixes food with digestive juices

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50
Q

segmentation last about

A

it lasts only 5-30 sec

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51
Q

how does segmentation happen?

A

it involves local ring like rhythmical contraction and relaxation of the gut in short and regular intervals

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52
Q

what is the use of segmentation?

A

it provides an increase in surface area for mixing of digestive juices with chyme

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53
Q

during segmentation there occurs a peristalsis, true or false

A

false

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54
Q

what is peristaltic movement?

A

is a progressive wave of strong contraction preceded by relaxation and it moves the bolus forward

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55
Q

what is receptive relaxation?

A

occurs in peristalsis and its where the muscular walls ahead of the ring relaxes

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56
Q

what stimulates peristalsis?

A

distension or stretch of the gut wall

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57
Q

which nerve plexus and nerve is responsible for coordination of peristalsis?

A

myenteric plexus and vagus nerve

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58
Q

propulsive segment happens when?

A

longitudinal muscle relaxes and circular muscle contracts

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59
Q

receiving segment happens when?

A

when longitudinal muscle contracts and circular muscle is inhibited

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60
Q

which neurotransmitter affects contraction in the GI?

A

Ach

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61
Q

which neurotransmitter is responsible for the relaxation of the GI?

A

NO or nitric oxide

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62
Q

what are the 2 principal control mechanisms involved in the regulation of GI?

A

neural and hormonal( endocrine and paracrine)

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63
Q

what are the 2 principal control mechanisms involved in the regulation of GI?

A

neural and hormonal( endocrine and paracrine)

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64
Q

neural control of GI involves?

A

somatic and the ANS

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65
Q

innervations of the digestive tract controls?

A

muscle contraction

secretion

absorption

blood flow

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66
Q

which part of the GI tract is controlled by somatic nerves?

A

the upper esophagus and external anal sphincter, these are voluntarily in action

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67
Q

true or false: somatic nerves regulate striated muscle indirectly

A

false they regulate it directly

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68
Q

autonomic regulation other name?

A

extrinsic regulation

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69
Q

vagus nerve or CN X innervate which part of the GI?

A

lower esophagus

stomach

small intestine

proximal large intestine

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70
Q

pelvic nerve innervates which part of the GI?

A

distal large intestine

sigmoid

rectum

anus

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71
Q

ANS influence___

A

ENS or enteric nervous system

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72
Q

what are the neurotransmitters of parasympathetic nerve?

A

cholinergic

Ach

VIP

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73
Q

from where does the parasympathetic originate from?

A

cranio- sacral (s2-4)

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74
Q

what does the parasympathetic do on the GI?

A

excitatory function :

->increase tone of the GI

->cause strong contraction of smooth muscles of the GI

->increase motility

->increase GI secretions

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75
Q

at the sphincters the parasympathetic does?

A

it causes dilation of circular smooth muscle which is lower esophageal and internal anal sphincters

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76
Q

parasympathetic terminates___

A

the ENS ganglia

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77
Q

what are the neurotransmitters of the sympathetic nerve?

A

adrenergic

nor adrenaline

adrenaline

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78
Q

what does the sympathetic does on the GI?

A

It has an inhibitory action which causes the relaxation of the smooth muscles of the GI

it reduces intestinal blood flow

at sphincters it causes constriction of the circular smooth muscles

it originates from thoraco-lumbar region (T5-L2)

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79
Q

intrinsic regulation is another name for?

A

enteric nervous system

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80
Q

___ is the primary neural control mechanism of the GI function

A

enteric nervous system

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81
Q

what does the enteric nervous system produce?

A

many stimulatory or inhibitory neurotransmitters that enhance or block GI motility

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82
Q

another name for Meissner’s plexus is?

A

inner plexus

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83
Q

other name for myenteric plexus is?

A

aurbache’s plexus or outer plexus

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84
Q

enteric nervous system is composed of 2 plexus, what are they?

A

aurbache’s plexus and sub mucosal plexus

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85
Q

the myenteric plexus controls?

A

GI motility

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86
Q

the Meissner’s plexus controls?

A

mainly absorption

secretion

blood flow

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87
Q

what is the name of the hormone that control the GI?

A

peptide hormones

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88
Q

the peptides hormones that act on the GI work through?

A

endocrine or paracrine pathways

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89
Q

what’s the effect of the peptide hormones ?

A

motility and secretary activities of the GI

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90
Q

list the hormones that are released in the GI

A

gastrin

cholecystokinin ( CCK)

secretin

motilin

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91
Q

how is gastrin secreted in the GI?

A

secreted by the G cells of the antrum of the stomach

antrum is the lower part of the stomach

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92
Q

what stimulates the secretion of gastrin?

A

ingestion of a meal or distention of the stomach

products of proteins and gastrin releasing peptide

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93
Q

what is the primary action of gastrin?

A

stimulation of HCL

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94
Q

how is the CCK secreted in the GI?

A

secreted by the i cells of duodenum and jejunum

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95
Q

the CCK is secreted in response to what?

A

in response to fatty acids. monoglycerides, peptides and amino acids

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96
Q

what is the function of the CCK?

A

it stimulates contraction of the gallbladder to release bile salts

it relaxes the sphincter of oddi ( the muscular valve surrounding the exit of the bile duct and pancreatic duct into the duodenum)

it stimulates pancreatic enzyme secretion

inhibits gastric emptying

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97
Q

How is secretin secreted?

A

secreted by the S cells of duodenum

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98
Q

what’s the stimulation for the secretion for secretin?

A

it’s secreted in response to HCL acid in the lumen of the duodenum and also fatty acids

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99
Q

what is the function of secretin?

A

it promote pancreatic secretion of HCO3 which neutralize the acid in the small intestine

it inhibits H+ secretion by gastric parietal cells

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100
Q

how is motilin secreted?

A

it’s secreted by the upper duodenum during fasting

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101
Q

what is motilin function?

A

it increase gastrointestinal motility

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102
Q

when does the secretion of motilin is inhibited?

A

after ingestion of food

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103
Q

how much blood supply does GI get?

A

at rest 25% of the cardiac output flows the GI

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104
Q

why 25% of blood goes to the GI?

A

for absorption

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105
Q

the GI blood glow is called?

A

splanchnic circulation

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106
Q

what is splanchnic circulation?

A

it is GI blood flow which includes the gut, spleen and pancreas

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107
Q

what happens in splanchnic circulation?

A

venous blood is collected from the gut, spleen and pancreas and pass through the portal circulation and end in the liver

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108
Q

what happens to the blood after it pass through the portal circulation and end in the liver?

A

it goes into liver sinusoids then hepatic vein then will enter inferior vena cava

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109
Q

what is the advantage of portal circulation?

A

harmful agents that come with the blood are destroyed by the macrophages of the liver which are called reticuloendothelial cells or Kupffer cells

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110
Q

what part of the brain controls food intake?

A

hypothalamus

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111
Q

hunger and feeding is stimulated by which part of the brain?

A

lateral hypothalamus

112
Q

the satiety feeling is stimulated by which part of the brain?

A

medial hypothalamus or ventromedial nucleus

113
Q

____is the voluntary intake of goof and drink

A

ingestion

114
Q

____is a part responsible for mechanical digestion of food by mastication

A

oral cavity

115
Q

what is chewing?

A

it’s mixing food with saliva and lubricating it to facilitate swallowing

it mixes ingested carbohydrate(CHO) with salivary amylase and begin the CHO digestion

116
Q

what is swallowing?

A

it’s movement of food from oral cavity into esophagus

117
Q

when is swallowing voluntarily and involuntary?

A

first it’s initiated voluntarily because the upper 1/3 of esophagus is skeletal so its regulated by somatic nerves and the rest is smooth muscle which will make the action involuntary which is regulated by ANS via enteric nervous system or directly

118
Q

the smooth muscle of the esophagus is innervated by?

A

the vagus nerves that synapse with myenteric neurons

119
Q

swallowing reflex 3 phases?

A

oral phase which is the only voluntary phase

pharyngeal

esophageal

120
Q

how much time does the swallowing reflex take?

A

8-10 secs

121
Q

the swallowing reflex is first initiated by___ and how?

A

by the tongue and it pushes the bolus against soft palate and back of the mouth triggering the swallowing reflex

122
Q

which part of the brain has the swallowing reflex center?

A

medulla oblongata

123
Q

what happens in the pharyngeal phase?

A

the medulla oblongata stimulate the closure of the nasal and tracheal opening and cause inhibition of respiration

upper esophageal sphincter relaxes while epiglottis closes to keep swallowed material out of airways

124
Q

what causes the esophageal phase?

A

caused by the stimulation of solid food on the walls of the esophagus

125
Q

what happens during the esophageal phase?

A

upper esophageal sphincter closes and creates a pressure powerful enough to push the bolus down the stomach

food moves downward into the esophagus propelled by peristaltic waves and gravity

126
Q

true or false: at rest upper and lower esophageal sphincter are opened?

A

false, they are closed and there is no backflow if gastric contents unless we are vomiting or belching( burping)

127
Q

what are the 2 types of protein secretions of saliva?

A

serous secretion

mucous and immunoglobin secretions

128
Q

what is serous secretion?

A

watery secretion that contains alpha amylase which is the dissolved zymogen granules

129
Q

mucous and immunoglobin secretions contain?

A

protein mucin that helps with lubrication, surface protection and anti bacterial effect

130
Q

list the constituents of saliva

A

water 99.5%

electrolyte like Na+, Cl_, K+, HCO3, Iodine…

enzymes like salivary amylase, lingual lipases, lysozymes, IgA, mucus…

131
Q

how much saliva we produce a day?

A

1-1.5 liters

132
Q

list the salivary glands

A

parotid gland

submandibular

sublingual

133
Q

what is the parotid gland?

A

it secrets mainly serous or watery fluid that is rich in ptyline which is amylase dissolved zymogen granules

134
Q

what is ptyline?

A

ptyline is salivary amylase

135
Q

the parotid gland is supplied by?

A

inferior salivary nucleus

136
Q

submandibular gland produce?

A

both serous or watery fluid and mucous fluid but no zymogen granules

137
Q

sublingual gland produce?

A

secret mainly thick mucous with little serous fluid

138
Q

what does the superior salivary nucleus supply?

A

both sub mandibular and sub lingual glands

139
Q

list the function of saliva

A

digestion

protection

speech facilitation

secretes HCO3

lubrication

oral hygiene

solvent for taste stimuli

140
Q

what is the digestion function of the saliva?

A

CHO digestion begins in the oral cavity by saliva

141
Q

how does saliva digest CHO?

A

by ptyline which breaks starch to maltose

also has lingual lipase which hydrolyze triglycerides

142
Q

what is the protection function of saliva?

A

it contains lysozyme and IgA that kills microbes

143
Q

why does profuse salivation occurs before vomiting?

A

the saliva protects the esophageal mucosa from corrosive action of HCl and chyme

144
Q

what is HCO3 function in the saliva?

A

its useful to make neutral media in the oral cavity and this is useful for ptyalin or salivary amylase action which is used for CHO digestion cause it does not work under acidic condition

145
Q

what is the lubrication function of saliva?

A

mucin is found in the saliva which facilitates moistening in the mouth

146
Q

explain the reflex control of salivation

A

Smell, test or touching of food ⇓

Activation of receptors in the oral (nasal) cavity

Sensory fibers from the tongue & nasal cavity send impulse to the nuclei in brain stem medulla oblongata, so called salivatory nuclei

Activation of parasympathetic fibers –act on salivary glands to increase salivary secretion

✓ Salivation can also be controlled by higher centers like hypothalamus appetite center which has nerve connections with salivatory nuclei in the medulla oblongata also involved in reflex control of salivation.

147
Q

secretion in the esophagus?

A

mucous glands secrete mucus which provide lubrication to facilitate swallowing and protect it from HCl during reflux

148
Q

list disorders of esophagus

A

gastro esophageal reflux disease or heart burn

achalasia

149
Q

heart burn occurs when?

A

when the cardial sphincter remains open or incompetence of the lower esophageal sphincter and this cause acid reflux in the lower esophagus causing a sensation of hurt burn

150
Q

achalasia occurs when?

A

when the lower esophageal sphincter remains closed and contracted and this will result bad smell and dilation of esophageal walls

151
Q

list the 3 functional regions of the stomach

A

fundus

body

antrum

152
Q

list the functions of the stomach

A

storage

mixing

controlled emptying of the chyme

secretion

protein digestion

anti septic action

153
Q

what is chyme?

A

it’s a semi fluid mixture of food with gastric secretion

154
Q

how does the stomach control emptying of chyme into the small intestine?

A

by pylorus sphincter

155
Q

list the active form of secretion in the stomach

A

parietal cells

chief cells

G cells

entrochromaffin cells

surface mucous cells

D cells

156
Q

parietal cells produce?

A

HCl and intrinsic factor

157
Q

chief cells produce?

A

pepsinogen

158
Q

G cells produce?

A

gastrin

159
Q

Entrochromaffin cells produce?

A

histamine

160
Q

surface mucous cells produce?

A

mucus and bicarbonate

161
Q

D cells produce?

A

somatostatin

162
Q

what is the active form of pepsinogen?

A

pepsin, so pepsinogen is the inactive form

163
Q

how is pepsinogen converted into pepsin?

A

HCl creates an acidic media in the stomach and that media is responsible for the conversion

164
Q

how does the G cells produce gastrin?

A

gastrin is produced during parasympathetic stimulation and this gastrin is responsible for the production of HCl

165
Q

protein digestion begin in?

A

the stomach cause of pepsin

166
Q

what’s the purpose of mucous secretion in the stomach?

A

it prevent the effect of HCl inside the stomach lumen

167
Q

___is a proteolytic enzyme

A

pepsin

168
Q

what happens during the cephalic stage of secretion?

A

vagal stimulation will cause chief cells to produce pepsinogen

169
Q

what happens during the gastric phase?

A

low PH activates pepsinogen secretion and the low PH will convert it into pepsin

170
Q

explain the HCl secretion

A

H+ ions that result from the dissociation of H2O in the cytoplasm of the parietal cells are continuously pumped through the membrane of the gland (canaliculi) into the gland lumen

Within the cell cytoplasm CO2 and OH- combine to produce bicarbonate ions, HCO3

Cl- are transported from the blood into the parietal cell and finally into the lumen of the gland by facilitated diffusion.

HCO3 in exchange to Cl-is transported in reverse direction (from the cytoplasm into the blood, charge balance).

Finally, H+ and Cl-ions combine in the lumen of the gland (pit) and produce HCl that is collected and stored in the pit until used for different physiological functions.

171
Q

gastric ulcer can develop when?

A

mucous layer and HCO3 production is minimized

172
Q

how does mucosal layer protect the lumen from acid attach?

A

because epithelial cells can produce thick mucous, HCO3 secretion and form tight junction

173
Q

what is gastric emptying?

A

it occurs when the chyme is small enough to pass through the pyloric sphincter so it’s highly dependent on the size, fluidity of the chyme

174
Q

which content can move past the pyloric sphincter easily?

A

CHO then protein and then fat( this being the least)

175
Q

which hormones facilitate and delay gastric empting?

A

CCK and secretin delay it by constricting pylorus

gastrin stimulates emptying by increasing stomach motility

176
Q

how does parasympathetic and sympathetic affect gastric emptying?

A

parasympathetic increase the rate by opening the pyloric sphincter

sympathetic delay emptying by constricting pyloric sphincter

177
Q

what is enterogastric reflex?

A

this reflex delay emptying

when fat and protein chyme reaches the duodenum sends impulses to enteric nerves of the stomach which inhibit motility and secretion

178
Q

what are physiological advantage of delaying gastric emptying ?

A

gives time for nutrients to stay in the stomach and be digested by gastric juice

it prevents HCl to not be damped into duodenum cause this might cause duodenal ulcers

its gives time for pancreatic secretions to reach duodenum and neutralize the acid HCl

prevent overwhelming of the small intestine with chyme

179
Q

what are the things that are being absorbed by the stomach?

A

alcohol

certain drugs like aspirin and morphine

small quantities of water

180
Q

what are the things that are NOT being absorbed by the stomach?

A

organic nutrients like glucose, amino acids

181
Q

what organ do we find adjacent to duodenum

A

the pancreas

182
Q

the pancreas act as?

A

function as both endocrine and exocrine glands

183
Q

list the function of the pancreas

A

produce digestive enzymes necessary to digest CHO, fat and protien

produce bicarbonates to neutralize gastric jucie

produce water and electrolytes like Na+ mnamn

184
Q

the digestive enzymes and electrolytes are produces by the pancreas are secreted by ?

A

acinar cells of the pancreas

185
Q

HCO3 and water are produces by the pancreas are secreted by ?

A

the cells lining the pancreatic duct cells

186
Q

the acinar cell is aided to produce enzymes by which neurotransmitters?

A

CCK and ACh

187
Q

duct cells are aided to produce HCO3 by which neurotransmitters?

A

secretin

188
Q

secretin is released from?

A

acid from the stomach release secretin from the wall of duodenum and fats and amino acids cause release of CCK

189
Q

enzymes are released into acini by?

A

vagal stimulation

190
Q

secretin causes___ and CCK causes___

A

secretin causes copious secretion of pancreatic fluid and HCO3

CCK causes secretion of enzymes

191
Q

list digestive enzymes produced by pancreas exocrine cells

A

amylases

protease and peptidases

lipases

nucleases

192
Q

which digestive enzyme produced by the exocrine cells digest proteins and peptides?

A

protease and peptidases

193
Q

which digestive enzyme produced by the exocrine cells digest carbohydrates?

A

amylases

194
Q

which digestive enzyme produced by the exocrine cells digest fats?

A

lipases

195
Q

which digestive enzyme produced by the exocrine cells digest nucleic acids?

A

nucleases

196
Q

pancreatic protease include?

A

chymotrypsin

trypsin

carboxypeptidase

197
Q

which protease enzyme protein to polypeptides?

A

chymotrypsin and trypsin

198
Q

which pancreatic enzyme splits polypeptides to amino acids?

A

carboxypeptidase

199
Q

which pancreatic enzyme is secreted in it’s active form?

A

pancreatic amylase and pancreatic lipase

200
Q

pancreatic amylase digest all carbohydrate except?

A

cellulose

201
Q

which compounds are changed to disaccharides by pancreatic amylase?

A

glycogen and starch

202
Q

___is secreted in its active form and it digests fat

A

pancreatic lipase

203
Q

what is the inactive from of trypsin?

A

trypsinogen

204
Q

trypsinogen is converted into trypsin by?

A

enterokinase

205
Q

what is the inactive form of chymotrypsin?

A

chymotrypsinogen

206
Q

chymotryspinogen is converted to chymotrypsin by?

A

trypsin

207
Q

acinar cells are filled with what?

A

secretary granules that contain different inactive protein proenzymes

208
Q

the acinar cells of pancreas must produce inactive pro enzymes because?

A

in order to avoid self destruction of its own tissues

209
Q

what does the pancreas do to avoid premature activation of proenzymes?

A

the acinar cells secrete trypsin inhibitor to inhibit the conversion of trypsinogen to trypsin

210
Q

what stimulates pancreatic secretion?

A

when fat food and HCl reach the duodenum evoke secretin and CCK secretion

211
Q

how does secretin stimulate pancreatic secretion?

A

secretin stimulates duct cells and produce large no of pancreatic juice that’s reach in bicarbonate

212
Q

how does CCK stimulate pancreatic secretion?

A

by stimulating acinar cells to release digestive enzymes

213
Q

what the significance of pancreatic enzyme secretion by CCK in small intestine?

A

digestion of fats and protein in small intestine

214
Q

what the significance of pancreatic bicarbonate secretion by secretin in small intestine?

A

neuralization of intestinal acid

215
Q

what is CCK role in gallbladder?

A

contraction

216
Q

what is CCK role in pancreas?

A

acinar secretion

217
Q

what is CCK role in stomach?

A

reduced emptying from the pylorus to small intestine

218
Q

what is CCK role in sphincter of oddi?

A

relaxation

219
Q

what’s the overall function of CCK?

A

protein, carbohydrate and lipid absorption and digestion

matching of nutrient delivery to digestive and absorptive capacity

220
Q

what is the function of liver in GI?

A

detoxify and eliminate toxins, drugs and metabolites

storage, metabolism and release of nutrients and some vitamins

synthesis of biologically important plasma protein like albumin, prothrombin clotting factors and apolipoproteins

synthesis and secretion of bile that optimizes the absorption of fats

role in immune function and clearance of intestinally absorbed bacteria

221
Q

the liver receives___ blood from the intestine

A

venous blood

222
Q

the digestive and excretory function of the liver are associated with____

A

the secretion of bile via the biliary tractthe secretion of bile via the biliary tract

223
Q

what are general features of bile?

A

it’s an alkaline fluid with Ph 8 that’s secreted in the liver

have bitter taste

dark green to yellowish brown fluid

250-1500 ml secreted daily

224
Q

where is bile stored? and when is it discharged?

A

stored in gallbladder during inter digestive period and discharged into duodenum during eating

225
Q

what are the constituents of bile?

A

bile salts or acids

bilirubin (bile pigment)

cholesterol, lecithin and protein

electrolytes

water, 84%

226
Q

what is the function of bile?

A

emulsification of fat and excretion of several toxic end products from the blood

227
Q

how does bile emulsify fats?

A

by changing large droplets of fats into smaller so they can be attacked by pancreatic lipase so it helps the absorption of fat from the small intestine

228
Q

what are toxic end products of blood that are excreted by bile?

A

bilirubin and excess cholesterol

229
Q

when CCK act on gallbladder what happens?

A

it contracts and increases bile flow into common bile duct

230
Q

when CCK acts on sphincter of oddi what happens?

A

it relaxes it and increase flow of bile into duodenum

231
Q

how does the gallbladder store bile?

A

it concentrates bile by reabsorbing water and electrolyte

232
Q

through what does gallbladder release bile to the duodenum?

A

through cystic and common bile duct

233
Q

how does gallstones occur?

A

when gallbladder is reabsorbing bile salts, bilirubin and cholesterol it becomes increasingly concentrated and they form solid crystals and as they become larger they form gallstones

234
Q

what does gallstones do?

A

they block the flow of bile which is known as obstructive jaundice

235
Q

which part of the SI does the pancreas head fit in?

A

duodenum

236
Q

what does duodenum mainly secretion?

A

mucous

hormones and

enzymes

237
Q

which part of the SI does the digestion begins in full spate?

A

jejunum

238
Q

what enters through jejunum?

A

bile and pancreatic enzymes

239
Q

___is part of SI where vigorous digestion and absorptive function takes place

A

ileum

240
Q

what type of diseases can develop due to fault of the SI?

A

mal absorption syndrome and short bowel syndrome

241
Q

what innervate the SI?

A

enteric and vagal nerves

242
Q

the inner lining of SI is greatly folded due to?

A

to increase the surface area for absorption

243
Q

what increase the surface of SI?

A

the microvillus

villi

greater foldings or plica circulares

244
Q

what are villi?

A

numerous finger like projections that emerge from the mucous membrane

245
Q

where can we find brush border?

A

at the surface of each villi

246
Q

what is brush border?

A

are minute microvilli, a layer of absorptive epithelial cells

247
Q

the epithelial cells of villi contain?

A

digestive enzymes like sucrase, maltase lactase and peptidases

248
Q

what does villi contain?

A

centrally located blood capillaries

lymphatic or lacteals

nerve fibers

connective tissues

249
Q

what are enzymes secreted in the SI?

A

brush border enzymes

pancreatic enzymes like sucrase, maltase and lactase

intestinal lipase

peptidases

250
Q

what does mucus inside the SI do?

A

it protects the intestinal wall and neutralize HCL

251
Q

where does almost all CHO digestion occur?

A

in the small intestine

252
Q

what digests CHO into disaccharides in SI?

A

pancreatic a-amylase

253
Q

what digests the disaccharides into monosaccharides in SI?

A

intestinal brush border enzymes like maltase, lactase and sucrase

254
Q

what is the end product of CHO?

A

fructose, glucose and galactose

255
Q

explain the summary of digestion of carbohydrates?

A

in the mouth polysaccharides are turned into shorter chains by salivary amylase, also disaccharides are turned into sucrose and lactose and these are turned into fructose or glucose and galactose or glucose in the SI respectively

in the SI pancreatic amylase turns oligosaccharides, dextrin and maltose into glucose, here sucrase, maltase and lactase have huge contributions too

256
Q

what is pepsin?

A

pepsinogen + H+

257
Q

list brush border enzymes

A

aminopeptidase

carboxypeptidase and dipeptidase

258
Q

explain the summery of digestion of proteins

A

in the stomach pepsin will turn polypeptides into shorter chains

inside SI brush border enzymes will turn shorter polypeptides and dipeptides into amino acids, here pancreatic enzymes like trypsin, chymotrypsin and carboxypeptidase also have contributions

259
Q

explain emulsification of lipids and why it happens

A

lipids must be emulsified or broken into smaller droplets by bile acid before being digested and this is for to increase the surface area for digestion

260
Q

explain the summary of digestion of fats

A

in the SI un-emulsified fat will get emulsified by bile from liver which is released by gallbladder and then this emulsified fat by the help of pancreatic enzyme called lipase it will turn into glycerol, fatty acids and monoglycerides

261
Q

what happens after vigorous digestion and absorption in the SI?

A

the remnants live and enter the large intestine and they are water insoluble

262
Q

list functions of the LI

A

absorption of water from the slurry and convert it into feces

electrolyte absorption mainly NaCl

mucous and bicarbonate secretion

storage, transport and evacuation of feces

absorption of vitamins and some drugs like aspirin

microbial fermentation

263
Q

what is microbial fermentation in LI?

A

the microbes in the colon synthesis vitamin K and B groups

264
Q

what are common diseases of LI?

A

colorectal cancer

appendicitis

constipation

265
Q

what are the 2 movements of colon?

A

haustrations and propulsive movement

266
Q

what is haustrations?

A

its a mixing movement of contractions that occur slowly and this will roll fecal matter and help expose it to the mucosal surface of the colon

267
Q

what is the importance of haustrations?

A

promotes efficient absorption of fluid and electrolyte from the colon

268
Q

what is mass or propulsive movement?

A

its produced by slow and continues haustral contractions and modified by peristaltic actions and this forces feces into rectum and the desire for defecation occurs

269
Q

when does mass movement occur?

A

1-3 days or once after a breakfast

270
Q

explain defecation reflex?

A

first pressure in rectum from mass movement sends afferent stimuli to spinal cord

parasympathetic stimuli cause contraction of rectal muscle and relaxation of internal anal sphincter

voluntary stimuli relax external sphincter and cause abdominal contraction

271
Q

____moves external anal sphincter during defecation

A

voluntary motor neuron

272
Q

what is the composition of feces?

A

normal feces have 75% water and 25% solid

273
Q

what is the bulk of fecal solids?

A

bacteria and undigested organic matter and fibers or cellulose

274
Q

what causes the brown color in feces?

A

due to urobilinogen produced by bacterial degradation of bilirubin

275
Q

what causes the odor in feces?

A

results from gases produced by bacterial metabolism like skatol, inodle and hydrogen sulfide

physiology 2 (4 decks)

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