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Alimentary System > Alimentary Physiology > Flashcards

Alimentary Physiology Flashcards

1
Q

What are the 4 functions of the GIT?

A

digestion
absorption
secretion
motility

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2
Q

Where does the GIT start and end?

A

Beginning of the oesophagus to the end of the rectum

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3
Q

What are the 3 pairs of salivary glands called?

A

Parotid
Sublingual
Submandibular

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4
Q

Where are the parotid salivary glands located?

A

Anterior the ears

Either side of the mouth

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5
Q

Where do the sublingual glands secrete from?

A

Underneath the tongue

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6
Q

Where do the submandibular glands secrete from?

A

From underneath the jaw

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7
Q

Can the oesophagus work against gravity?

A

Yes

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8
Q

By what motility movement does food pass down the oesophagus?

A

Peristalsis

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9
Q

What is the primary role of the stomach?

A

Storage

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10
Q

Is the stomach an acidic or alkaline environment?

A

Acidic

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11
Q

What is the primary role of the pancreas?

A

To secrete enzymes and hormones

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12
Q

What is the functions of saliva?

A

To act as a lubricant when chewing and breaking down food

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13
Q

What is the function of the gallbladder?

A

Store and concentrates bile

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14
Q

How much bile can the gall bladder store?

A

up to 50ml

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15
Q

What colour is the gall bladder?

A

Green

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16
Q

What is the main function of the small intestine?

A

Nutrient absorption

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17
Q

What is the primary function of the large intestine?

A

Water absorption and the formation of faeces

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18
Q

What are the 4 layers of the tube wall of the GIT?

A

Mucosa
Submucosa
Muscularis Externa
Serosa/Adventitia

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19
Q

What are the 3 layers of the mucosa?

A

Epithelium
Lamina propria
muscularis mucosae

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20
Q

What is the change in epithelium from the mouth and oesophagus to the stomach, small and large intestine?

A

Mouth, oesophagus - stratified squamous epithelium

Stomach ect.. - simple columnar

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21
Q

Why does the epithelium differ along the GIT?

A

Differs for adaptation to function

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22
Q

What is the lamina propria composed of?

A

Loose connective tissue

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23
Q

What is the submucosa composed of?

A

Thick irregular connective tissue

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24
Q

What is the function of the submucosa?

A

To support the mucosa

Both psychically and with blood vessels ect..

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25
Q

What is the submucosal plexus?

A

Extensive neuron network surrounding the submucosa

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26
Q

What is the muscularis externa composed of?

A

2 concentric thick layers of smooth muscle
Inner circular
Outer longitudinal

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27
Q

What is the inner layer of concentric muscle in the muscularis externa?

A

Circular muscle

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28
Q

What is the outer layer of concentric muscle in the muscularis externa?

A

Longitudinal muscle

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29
Q

What does the circular muscle control?

A

Lumen diameter

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30
Q

What does the longitudinal muscle control?

A

The length of the gut tube

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31
Q

What is the name of the neuron network in the muscularis externa?

A

Myenteric plexus

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32
Q

What is the myenteric plexus + submucosal plexus =?

A

Enteric nervous system

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33
Q

What is the difference between the serosa and the adventitia?

A

Adventitia - located outside the peritoneal cavity

Serosa- located within the peritoneal cavity

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34
Q

Which nerve transmits parasympathetic activity to the GIT?

A

Vagus nerve

CN X

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35
Q

From which cranial nerve does the vagus nerve originate?

A

Cranial nerve 10

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36
Q

Is the vagus nerve stimulatory or inhibitory of the digestive system?

A

Stimulatory - REST AND DIGEST

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37
Q

Which nerves innervate parasympathetic activity on salivation?

A

Facial and glossopharyngeal nerves

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38
Q

Which nerve transmits sympathetic activity to the GIT?

A

Splanchnic nerves

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39
Q

Is the sympathetic nervous system inhibitory or stimulatory of the GIT activity?

A

Inhibitory - FLIGHT OR FIGHT

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40
Q

What are the 3 main branches of the abdominal aorta that supply the GIT?

A

Celiac trunk
Superior mesenteric artery
Inferior mesenteric artery

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41
Q

Which part of the gut does the celiac trunk supply?

A

Foregut

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42
Q

Which part of the gut does the superior mesenteric artery supply?

A

Midgut

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43
Q

Which part of the gut does the inferior mesenteric artery supply?

A

Hindgut

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44
Q

Give examples of organs found in the foregut?

A

Stomach
Pancreas
Liver
Gallbladder

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45
Q

Give examples of organs found in the midgut?

A

Small intestine
Ascending colon
Proximal 2/3 of transverse colon

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46
Q

Give examples of organs found in the hindgut

A

Descending colon
Sigmoid colon
Rectum
Distal 1/3 transverse colon

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47
Q

Which veins drain the stomach?

A

Gastric veins

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48
Q

Which veins drains the pancreas?

A

Splenic vein

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49
Q

Which vein drains the midgut?

A

Superior mesenteric vein

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50
Q

Which vein drains the hindgut?

A

Inferior mesenteric vein

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51
Q

Where do the superior and inferior mesenteric vein drain into?

A

Hepatic portal vein

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52
Q

Where does the hepatic portal vein drain into?

A

Hepatic vein

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53
Q

Where does the hepatic vein drain into?

A

IVC

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54
Q

Which artery supplies the liver?

A

Hepatic artery

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55
Q

Which vein drains the liver?

A

Hepatic vein

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56
Q

Describe the blood in the hepatic artery

A

Oxygen rich

Nutrient deficient

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57
Q

Describe the blood in the hepatic vein

A

Oxygen deficient

Nutrient rich

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58
Q

What are the 3 principal dietary constituents?

A

Carbohydrates
Proteins
Fats

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59
Q

What are the 3 monosaccharides?

A

Glucose
Galactose
Fructose

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60
Q

What are the 3 disaccharides?

A

Lactose
Sucrose
Maltose

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61
Q

Which digestive enzyme breaks down lactose?

A

Lactase

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62
Q

Which digestive enzyme breaks down Maltose?

A

Maltase

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63
Q

Which digestive enzymes breaks down sucrose?

A

Sucrase

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64
Q

What is the plant storage form of glucose?

A

Starch

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65
Q

What the the animal storage of glucose?

A

Glycogen

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66
Q

Why can’t our digestive enzymes break down cellulose?

A

Because we don’t produce the enzyme cellulase

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67
Q

Where is cellulose broken down?

A

In the colon

By bacteria

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68
Q

Which enzyme breaks down starch and glycogen?

A

Alpha amylase

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69
Q

Which bonds link glucose monomers in starch and glycogen?

A

Alpha 1,4- glycosidic bonds

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70
Q

Which epithelium covers villi?

A

Columnar epithelium

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71
Q

What structure is the villi covered in?

A

Microvilli

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72
Q

Which is villi then covered in microvilli?

A

To increase surface area for absorption even further

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73
Q

Which membrane is on the outer surface of the vili?

A

Apical membrane

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74
Q

Which membrane is on the inner surface of the villi?

A

Basolateral membrane

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75
Q

What is meant by transcellular?

A

Going through the cell

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76
Q

What is meant by paracellular?

A

Can pass between the cells as they are not entirely tight

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77
Q

How many proteins are needed to transport molecules through a cell?

A

At least 2
One to get in
One to get back out

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78
Q

To which ion is glucose transport coupled up to?

A

Sodium

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79
Q

Through which protein is glucose transported?

A

GLUT 2

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80
Q

Which transporter transports fructose into the cell?

A

GLUT 5

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81
Q

Which transporter transports fructose back out of the cell?

A

GLUT 2

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82
Q

What are proteins polymers of?

A

Amino acids

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83
Q

Which bond links amino acids to form proteins?

A

Peptide bonds

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84
Q

Give an example of a post-translational modification in a protein

A

the addition of carbohydrate

the addition of a phosphate

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85
Q

Enzymes which hydrolyse peptide bonds are known as what?

A

Proteases

or Peptidases

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86
Q

Where do endopetidases act on?

A

The inside of the protein

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87
Q

Where do ectopeptidases act on?

A

On the terminal amino acids of the protein

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88
Q

What are the 2 reactions involved in the formation and breakdown of proteins?

A

Hydrolisation

Condensation

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89
Q

What are most ingested fats in the form of?

A

TAG

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90
Q

Which enzyme breaks down fats?

A

Pancreatic lipase

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91
Q

How does TAG present itself in the GIT?

A

As large lipid droplets that are insoluble in water

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92
Q

Is lipase a water soluble enzyme?

A

Yes

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93
Q

What does pancreatic lipase break TAG down into?

A

Monoglyceride + 2 FA

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94
Q

Why is gut motility in the small intestine important?

A

Breaks fat globules apart into smaller droplets

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95
Q

What is emulsification?

A

Dividing large lipid droplets into smaller droplets

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96
Q

Why is emulsification vital?

A

As it increases the surface area of the fat therefore allowing more accessibility for LIPASE action

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97
Q

What 3 things does emulsification require?

A

Mechanical disruption
Emulsifying agent
Amphiphatic molecule

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98
Q

What is an amphiphatic molecule?

A

A molecule that has a polar and a non-polar section

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99
Q

Are micelles absorbed?

A

No

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100
Q

What are micelles constantly doing?

A

Breaking down and reforming

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101
Q

Why do micelles constantly break down and reform at the surface of the villi?

A

To feed a small pool of monoglycerides and fatty acids that are in solution

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102
Q

What part of the fat does the villi absorb?

A

The freely dissolved monoglycerides and fatty acids

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103
Q

Why can monoglycerides and FA just diffuse across the cell membrane?

A

Because of there non-polar nature

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104
Q

Once in the cell what happens to the monoglyceride and FA?

A

They enter the sER

And formed back into TAG

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105
Q

Where is TAG processed in the cell/

A

In the Golgi apparatus

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106
Q

What are extracellular fat droplets known as?

A

Chylomicrons

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107
Q

Where do chylomicrons pass into?

A

Lacteals

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108
Q

What are lacteals the terminal endings of?

A

Lymphatic system

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109
Q

What are the 2 classes of Vitamins?

A

Fat soluble

Water soluble

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110
Q

Give examples of fat soluble vitamins

A

A,D,E,K

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111
Q

Give examples of water soluble vitamins

A

B, C folic acid

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112
Q

How are fat soluble vitamins absorbed?

A

They follow the same path as absorbed fats

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113
Q

How is Vitamin B12 absorbed?

A

Using an intrinsic factor in the stomach

By specific mechanisms in the distal ileum

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114
Q

Where is vitamin B12 stored?

A

In the liver

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115
Q

Why is vitamin B12 vital for the body?

A

Important for the maturation of RBC

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116
Q

What does vitamin B12 deficiency lead to?

A

Leads to the failure of RBC maturation

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117
Q

What % of daily ingested iron is absorbed into the blood?

A

10%

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118
Q

Where is iron stored?

A

Ferritin

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119
Q

When blood iron is low what does the body do?

A

Uses ferritin stores

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120
Q

What is hyperaemia?

A

When there is increased ferritin levels and therefore more iron bound to RBC

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121
Q

What is anaemia?

A

When there is decreased ferritin levels

As more iron has been released to the blood

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122
Q

Why do we chew?

A

To prolong the taste experience

Defence against respiratory failure

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123
Q

How is chewing controlled?

A

Somatic nerves

Skeletal muscles of the mouth and jaw

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124
Q

Describe the chewing reflex

A

Contraction of jaw muscles
pressure of food against gums, hard plate and tongue
Mechanoreceptors detect this increase in pressure
Lead to a reduced pressure
Contraction is stimulated again

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125
Q

What is present in saliva?

A 
Water 
Mucins 
A-amylase 
Electrolytes 
Lysozyme
126
Q

Is the sympathetic system inhibitory or stimulatory of saliva production?

A

Stimulatory

127
Q

Is the sympathetic system inhibitory or stimulatory of saliva production?

A

Stimulatory

128
Q

Describe the saliva produced when the parasympathetic nervous system takes over

A

Profuse watery salivary secretion

129
Q

Describe the saliva produced when the sympathetic nervous system takes over

A

Small volume

Viscous saliva

130
Q

What is the oesophagus the conduit between?

A

The pharynx and stomach

131
Q

How long is the oesophagus?

A

25cm

132
Q

What 4 layers does the oesophagus consist of?

A

Mucosa
Submucosa
Muscularis Externa
Adventitia

133
Q

What type of epithelium is found in the oesophagus?

A

Stratified squamous

134
Q

Does the oesophagus contain smooth or skeletal muscle?

A

Both

135
Q

What type of muscle is found in the upper 1/3 of the oesophagus?

A

Skeletal

136
Q

What type of muscle is found in the lower 2/3 of the oesophagus?

A

Smooth

137
Q

Describe the oral phase of swallowing

A

Bolus is pushed to the back of the mouth by the tongue

138
Q

Describe the pharyngeal phase of swallowing

A

Presence of bolus
Sequence of reflex contraction by pharyngeal muscles
Co-ordinated swallowing centre
Soft palate reflected backwards and upwards
Closes of nasopharynx

139
Q

What closes over when swallowing?

A

Epiglottis

140
Q

Why doe the epiglottis close over when swallowing?

A

To prevent the entry of the bolus into the trachea

141
Q

What contracts when food has entered the oesophagus?

A

Upper Oesophageal Sphincter

142
Q

By what movement does food travel down the oesophagus?

A

Peristalsis

143
Q

How long is food in the oesophagus for?

A

Approx 10 seconds

144
Q

What happens when the bolus approaches the stomach?

A

The lower oesophageal sphincter relaxes

145
Q

What are the functions of the stomach?

A

Temporary storage of ingested material
Dissolve food particles and initiate digestion
Control delivery of contents to the small intestine
Sterilisation
Produce intrinsic factor for Vitamin B12 absorption

146
Q

What is the name of the outer layer of the stomach?

A

Serosa

147
Q

What are the 3 layers of muscularis externa in the stomach?

A

Longitudinal
Circular
Oblique

148
Q

What folds are present in the stomach?

A

Rugae

149
Q

What is the purpose of the rugae in the stomach?

A

To allow an increase in volume of the stomach without an increase in pressure

150
Q

what are the 2 curvatures of the stomach?

A

Greater

Lesser

151
Q

What does the lesser omentum join?

A

Liver

Lesser curvature of the stomach

152
Q

Where does the greater omentum pass?

A

Greater curvature of the stomach
To transverse colon
Folding back on itself

153
Q

What is the function of the fundus?

A

Primarily there for storage

154
Q

Which acid is present in the stomach?

A

HCl

155
Q

What is pepsinogen the inactive form of?

A

Pepsin

156
Q

What does the intrinsic factor produced by the stomach act on?

A

Vitamin B12

157
Q

Why does the antrum have a very thick muscular wall?

A

For the mixing and grinding down of solid food

158
Q

What are the 3 muscle layers of the muscularis externa of the stomach?

A

Longitudinal
Circular
Oblique

159
Q

Does the oesophagus have a mucous lining?

A

no

160
Q

What does gastrin control the release of?

A

HCl and pepsinogen

161
Q

What do mucous neck cells secrete?

A

Mucous

162
Q

What do parietal cells do?

A

Release HCl and intrinsic factor for vit B12

163
Q

What is the function of acid in the stomach>

A

To kill pathogens
Create an acidic environment
Aid digestion

164
Q

What is the optimal pH for pepsin?

A

1.8-3.5

165
Q

Describe the formation of acid by parietal cells in the stomach

A

CO2 from the blood enters the cells
Reacts with water to form carbonic acid
H+ is pumped out of the cell with K+
At the same time Cl- is pumped into the cell from the blood
Cl- is then pumped into the stomach lumen
Cl- and H+ in the stomach lumen react to form HCl

166
Q

What are the 3 regulatory molecules that stimulate the release of HCl from parietal cells?

A

Acetylcholine
Histamine
Gastrin

167
Q

What 3 mechanisms control acid secretion?

A

Neurocrine - vagus/acetylcholine
Endocrine - gastrin
Paracrine (locally)- histamine

168
Q

Describe the cephalic phase

A

Stimuli such as smell, taste, sight of food are processed in the brain
Activate parasympathetic neurons
travelling in the vagus nerve
increase acetylcholine production
Stimulate G cells to produce gastrin
Gastrin then stimulates ECL cells to produce histamine

169
Q

Describe the gastric phase

A 
Food is present in the stomach 
Stimulates vagal reflexes 
to release ACh
Stimulates acid secretion 
G cells produce gastrin 
Gastrin and ACh stimulate the release of histamine
170
Q

Describe the intestinal phase

A

Acid in the duodenum suggests stomach emptying
reduces the effect of gastrin on parietal cells
Switching off acid production in the cell

171
Q

What is the effect of acid in the duodenum on the stomach ?

A

Stops stomach emptying

172
Q

What are enterogastrones?

A

Hormones released from gland cells in duodenal mucosa

173
Q

What are the 3 enterogastrones?

A

Secretin
CCK
GIP

174
Q

What are enterogastrones released in response to?

A

acid, FA or peptides in the duodenum

The suggestion of stomach emptying

175
Q

What are the 2 strategies that enterogastrones uses to neutralise the pH in the duodenum?

A

Inhibit gastrin secretion

Reduce gastric emptying by contracting the pyloric sphincter

176
Q

What is pepsinogen?

A

The inactive form of pepsin as found in the stomach

177
Q

Why does pepsin have to be in the form of pepsinogen?

A

Because the stomach is composed of protein and pepsin would just digest it

178
Q

Does pepsin work in acidic or alkaline conditions?

A

Acidic

179
Q

What happens to pepsin at neutral pH?

A

It is inactivated

180
Q

What is the primary role of gastric mucous?

A

To have a cytoprotective role
protect the mucosal surface from acid corrosion, mechanical injury and ensure pepsin has no protealytic function on the stomach lining

181
Q

What cells produce the intrinsic factor in the stomach?

A

Parietal cells

182
Q

What is the intrinsic factor produced by the stomach vital for the absorption of?

A

Vitamin B12

183
Q

How much gastric quantity enters the duodenum from the stomach?

A

Only a small quantity of chime

184
Q

What effect does CCK have on other organs in the GI tract?

A

Stimulates contraction of the gallbladder

Stimulates pancreatic enzyme secretion

185
Q

What does secretin stimulate the release of from the pancreas?

A

Bicarbonate

186
Q

What is GIP released in response to?

A

Glucose, FA and amino acids in the duodenum

187
Q

What is the storage molecule for iron?

A

Ferritin

188
Q

What does ferritin do?

A

Acts as a buffer for when blood iron levels are lower

Acts as a storage for iron

189
Q

Why does the body of the stomach have athin muscle layer?

A

Because no mixing occurs here

primarily for storage

190
Q

Why does the antrum of the stomach have much thicker muscle?

A

Because it does alot of mixing

and produces powerful contraction

191
Q

What does the pyloric sphincter control?

A

The release of chime from the stomach to the duodenum

192
Q

how many peristaltic waves are produced a minute?

A

3

193
Q

Where are peristaltic waves generated?

A

In pacemaker cells

194
Q

Will the slowest of fastest cells dictate the pace of the peristaltic wave?

A

Slowest

195
Q

How is a peristaltic wave conveyed through the GI tract?

A

Through gap junctions in the longitudinal muscle layer

196
Q

How is peristalsis stimulated?

A

By hormonal control

G cells producing gastrin

197
Q

What is the effect of gastrin on peristalsis?

A

Increases contraction

198
Q

What inhibits peristalsis?

A

The arrival of anything in the duodenum

Suggesting the stomach has emptied

199
Q

What determines the strength of contraction in peristaltic waves?

A

Number of APs

200
Q

What is released when there is acid present in the duodenum?

A

Secretin

201
Q

What does secretin stimulate the release of?

A

Bicarbonate

202
Q

How is secretin inhibited?

A

By acid neutralisation in the duodenum

203
Q

Secretin inhibition i an example of what mechanism?

A

Negative feedback

204
Q

What are the 3 parts of the pancreas?

A

Head
Body
Tail

205
Q

Anatomically where does the head of the pancreas lie?

A

In the curvature of the duodenum

206
Q

Where does the tail of the pancreas extend to?

A

The spleen

207
Q

Where does the endocrine portion of the pancreas release contents to?

A

Bloodstream

208
Q

What do islet cells produce?

A

Insuline and glucagon

209
Q

What do insulin and glucagon do?

A

Control blood glucose levels

210
Q

Where does the exocrine portion of the pancreas secrete to?

A

The cavity of the duodenum

211
Q

What are the functional unit of acinar cells?

A

Lobules

212
Q

How are lobules of the pancreas connected?

A

Via intercalated discs

213
Q

What does the pancreatic duct eventually join?

A

The common bile duct

214
Q

Where do the bile ducts and pancreatic duct join?

A

At the sphincter of oddi

215
Q

What is the purpose of the accessory pancreatic duct?

A

Provides an alternative route if the main pancreatic duct is obstructed

216
Q

What is the exocrine portion of the pancreas responsible for?

A

The digestive function of the pancreas

i.e the release of pancreatic digestive enzymes

217
Q

What is the optimal pH of pancreatic enzymes?

A

Neutral

218
Q

Which cells of the pancreas release enzymes?

A

Acinar cells

219
Q

Which cells of the pancreas release hormones?

A

Islet cells

220
Q

What do acinar cells store enzymes in the form of?

A

Inactive zymogen granules

221
Q

Why do acinar cells store enzyme as zymogen?

A

to prevent autodigestion of the pancreas

222
Q

Where is enterokinase found?

A

bound to the brush border of duodenual enterocytes

223
Q

What do enterokinases do?

A

Convert trypsinogen to trypsin

224
Q

What does trypsin do?

A

Converts all other zymogens to active forms

225
Q

What do proteases do?

A

Cleave peptide bonds

226
Q

What do nucleases do?

A

Hydrolyse DNA/RNA

227
Q

What do elastases do?

A

Stimulate collagen digestion

228
Q

What do phospholipases do?

A

Convert phospholipids to amino acids

229
Q

What do lipases do?

A

Convert TAG to FA and glycerol

230
Q

What does alpha-amylase do?

A

Converts starch to glucose+maltose

231
Q

What is Zymogen secretion stimulated by?

A

CCK

232
Q

What is the largest single organ in the body?

A

Liver

233
Q

Where is the liver located?

A

In the upper right quadrant of the abdomen

234
Q

What are the 2 major lobes of the liver?

A

Right and left

235
Q

What are the 2 minor lobes of the liver?

A

Caudate

Quadrate

236
Q

Where do the pancreatic and common bile duct drain into?

A

Sphincter of Oddi

237
Q

What is the bare area of the liver?

A

Small diaphragmatic surface not surrounded by peritoneal cavity

238
Q

What shape are lobules?

A

Hexagonal

239
Q

What is present at the corners of lobule?

A

Portal triads

240
Q

What composes the portal triad?

A

Hepatic portal vein
Hepatic artery
Hepatic duct

241
Q

What is present in the center of lobules?

A

Central vein

242
Q

Where do central veins drain into?

A

Hepatic veins - IVC

243
Q

Where do hepatic cords radiate from?

A

From the central veins

244
Q

What is the space between hepatic cords known as?

A

Hepatic sinusoids

245
Q

Why does the liver have dual blood supply?

A

To have nutrient and oxygen rich blood

246
Q

Describe the venous blood supply to the liver

A

O2 depleted
Nutrient rich
Through hepatic portal vein
Go to central vein

247
Q

Describe the arterial blood from the left side of the heart to the liver

A 
O2 rich 
nutrient deplete 
travels through hepatic artery 
going to central veins 
Drained by hepatic veins
248
Q

What is the alimentary role of the liver?

A

Production and secretion of bile

249
Q

What is bile produced by?

A

The breakdown of haemoglobin in the spleen

Haem travels to the liver

250
Q

What colour is bilirubin?

A

Yellow

251
Q

What colour is bilirubin that has been modified by bacterial enzymes?

A

Brown

252
Q

What colour is bilirubin that has been reabsorbed and excreted in urine?

A

Yellow

253
Q

What are bile acids synthesised from?

A

in the iver from cholesterol

254
Q

Where does the gallbladder drain into?

A

Cystic duct

255
Q

Where does the cystic duct drain into?

A

The bile duct

256
Q

What controls the release of bile and pancreatic juice into the duodenum?

A

Sphincter of oddi

257
Q

To what times does the gallbladder concentrate bile?

A

5-20

258
Q

What effect does CCK have on the sphincter of oddi?

A

Causes it to relax - i.e to open

259
Q

What effect does CCK have on the gallbladder?

A

Contracts it

260
Q

How long is the small intestine?

A

6 metres

261
Q

What is the function of the duodenum?

A

Gastric acid neutralisation
Digestion
Iron absorption

262
Q

Where is the main site of nutrient absorption?

A

Jejunum

263
Q

What are the folds in the lumen of the small intestine that increase surface area?

A

Plicae

264
Q

What are the finger like projections found in the small intestine?

A

Villi

265
Q

What is the villi lined with?

A

Microvilli

266
Q

What is the function of crypt cells?

A

To secrete Cl and Water

267
Q

What effect does CF have on crypt cells?

A

Complete inability to transport Cl meaning water cannot be released

268
Q

How is H2O secreted in the lumen of the small intestine?

A

Chloride is actively secreted into the intestinal lumen
Creating an osmotic concentration gradient
Dragging water with it

269
Q

How much water does the small intestine secrete?

A

1500ml

270
Q

Why is water so important in the intestinal lumen?

A

Maintains lumenal contents in liquid state
promotes mixing
Aids nutrient presentation to the absorbing surface
Dilutes and washes away potentially injurious substances

271
Q

What are the 2 types of motility in the small intestine?

A

Segmentation

Peristalsis

272
Q

Describe segmentation motility

A

Squeezing from the middle
Then the sides
To allow the thorough mixing of chyme

273
Q

Describe peristalsis motility in the small intestine

A

Contraction behind

Relaxation in front

274
Q

How does segmentation produce slow migration of chyme towards the large intestine?

A

More chyme is pushed down than up

275
Q

In what direction does peristalsis move?

A

Oral to anal direction

276
Q

What is the start of the large intestine called?

A

The caecum

277
Q

What are the 4 parts of the colon?

A

Ascending
Transverse
Descending
Sigmoid

278
Q

What type of epithelium is found in the large intestine?

A

Simple columnar epithelium

279
Q

Why is the epithelium in the colon flat?

A

To allow chyme to pass through the colon easily

280
Q

Describe crypt cells in the colon

A

Large straight crypt cells

281
Q

What is the function of crypt cells in the colon

A

To produce mucous for lubrication for the movement of faeces

282
Q

Describe the muscularis externa in the rectum

A

Thick compared to other regions of the GI tract

283
Q

What are the 2 sphincters in the anal canal?

A

Internal anal sphincter

Voluntary external anal sphincter

284
Q

What epithelium is in the anal canal?

A

Stratified squamous epithelium

285
Q

What is broken down by bacterial in the colon?

A

Cellulose

286
Q

How does the colon absorb water?

A

Sodium is actively transported from the lumen into the blood
This creates an osmotic concentration gradient
Dragging water out of the lumen
Dehydrating the faeces

287
Q

What does bacterial fermentation of undigested carbohydrate produce?

A

Short chain FA

288
Q

Does the colon have an absorption role?

A

No - not in humans

289
Q

Describe defacation

A

There is a wave on intense contraction from the colon to the rectum

There is a feeling of stretch in the rectum

Mechanoreceptors

Defacation reflex - urge to poo

290
Q

During constipation can the colon absorb toxins from faecal material?

A

No

291
Q

What is diarrhoea?

A

Too frequent passage of faeces which are too liquid

292
Q

What is the primary function of the colon?

A

Dehydration of chyme

293
Q

What is the submucosa composed of?

A

Connective tissue

294
Q

What is the difference between the serosa and the adventitia?

A

Serosa- within the peritoneal cavity

Adventitia - outwith the peritoneal cavity

295
Q

Why does the epithelium of the gut tube differ along the GI tract?

A

Adaptation for function

296
Q

From which nerve does the vagus originate?

A

Cranial nerve 10

297
Q

Does a vagotomy have any effect on salivation?

A

No as salivation is controlled by facial nerves and glossopharyngeal nerve

298
Q

What does the Celiac trunk branch into?

A

Left gastric artery
Splenic artery
Common hepatic artery

299
Q

Are micelles absorbed?

A

No they are constantly breaking down and reforming close to the surface

300
Q

Where are FA and monoglyceride ocmposed back into TAG when back in the cell?

A

Endoplasmic reticulum

301
Q

What are the largest salivary glands?

A

Parotid glands

302
Q

Why does the nasopharynx close when swallowing?

A

To prevent food coming up the nasal cavity

303
Q

What type of muscle is located in the oesophagus?

A

Upper 1/3 - skeletal
Middle 1/3 - mix of skeletal and smooth
Lower 1/3 - smooth muscle

304
Q

Glucose + galactose =

A

Lactose

305
Q

Glucose + glucose =

A

maltose

306
Q

Fructose + glucose =

A

Sucrose

307
Q

Covering of small intestine epithelium

A

Simple columnar epithelium

308
Q

Bonds that link proteins

A

peptide bonds

309
Q

which enzyme carries out fat digestion?

A

Pancreatic lipase

310
Q

Action of secretin

A

Stimulate bicarb release from pancreas

Inhibits gastric emptying

311
Q

Action of CCK

A

Stimulates contraction of gallbladder
And pancreatic enzyme secretion
Inhibits gastric emptying

312
Q

6 components of bile

A 
bile acids 
lecithin 
cholesterol  
bie pigments
toxic metals 
bicarb

Alimentary System (29 decks)

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