Gastro Flashcards
1
Q
Give the mucosa of the lip (histology)
A
- stratified squamous keratinising epithelium (at the skin margin)
- stratified squamous non-keratinising epithelium (in the mouth)
2
Q
What is the muscle that surrounds the mouth called
A
- orbicularis oris muscle
- it is striated muscle
3
Q
Give the mucosa on the ventral and dorsal surface of the tongue
A
- ventral surface has non keratinised stratified squamous epithelium
- dorsal surface has keratinised stratified squamous epithelium
4
Q
Where do the extrinsic and intrinsic muscle fibres of the tongue attach to
A
- the extrinsic muscles attach to the lower jaw
- the intrinsic muscles attach to fibrous connective tiss under the mucosa
5
Q
What are the papillae of the tongue
A
-the dorsum of the tongue has folds called papillae
6
Q
Which papillae are most common and where are these usually located
A
-filliform papillae - tall, pointed and they cover the whole anterior 2/3 of the tongue
7
Q
Which papillae are not so common and where are these usually located
A
-fungiform papillae - mushroom shaped and found at the tips and sides of the tongue
8
Q
Where are taste buds usually found on the tongue
A
- on the lateral side of the fungiform papillae
- on the circumvallate papillae which separate the anterior 2/3 and posterior 1/3 of the tongue
9
Q
Which papillae have taste buds and where are they located
A
- the circumvallate papillae
- v shaped row that separates the anterior 2/3 and posterior 1/3 of the tongue
10
Q
What does the gland secretions of the parotid gland contain
A
-serous, enzyme rich secretions with alpha amylase that digest starch
11
Q
What are the secretory cells of the parotid gland
A
-pyramidal with spherical nucleus
12
Q
What type of epithelium lines the ducts that the acini drain into
A
-simple cuboidal epithelium that might become stratified at the end
13
Q
What can striated ducts of the acini do to saliva
A
-adjust the ionic composition of saliva
14
Q
What do the secretions of the sublingual gland contain
A
- sticky mucus that lubricates the mouth and bolus of food
- mucus made of high molecular weight mucopolysaccharide that is good at absorbing large amounts of water
15
Q
What shape are the secretory cells of the sublingual glands
A
-appear swollen with oval nucleus squashed to the base of the cell
16
Q
What do the secretions of the submandibular gland contain
A
-mix of serous and mucous secretions
17
Q
What are the shapes of the secretory cells of the submandibular glands
A
-crescent shaped demi-lunes (half moons) which are the serous cells that lie at the end pf mucous secreting tubules
18
Q
Which two salivary glands are major sources of epidermal growth factor that promote growth of the epithelium in the GI tract
A
- parotid gland
- submandibular gland
19
Q
Give the epithelium of the surfaces of the epiglottis
A
- most of its surface is covered by stratified squamous epithelium
- the lower part of it’s posterior surface is covered by respiratory epithelium (pseudostratified columnar ciliated epithelium)
20
Q
What are the four layers of the gastrointestinal tract
A
- innermost mucosa
- underlying submucosa
- external muscle coat (muscularis propria sometimes called muscularis externa)
- serosa (simple squamous epithelium covering the surface of the gut tube facing the peritoneal cavity)
21
Q
Give the 3 layer components of the innermost mucosa in the GI tract
A
- lining epithelium (usually thrown into folds)
- lamina propria
- muscularis mucosa (ring of smooth muscle)
22
Q
What does the submucosa in the GI tract contain
A
- glands and lymphoid tissue
- blood vessels that supply the gut
- Meissner’s plexus (part of the enteric nervous system)
23
Q
What does the muscularis propria of the GI tract contain
A
- two layers of smooth muscle (circular and longitudinal), their contractions help to break up the food and propel it along the alimentary tract
- auerbach’s plexus (part of the enteric nervous system) in between the two layers of muscle
24
Q
What epithelium lines the oesophagus
A
-stratified squamous non-keratinising epithelium
25
At what end does the oesophagus have a thicker and more prominent muscle layer in its muscularis mucosa
-the gastric (distal) end
26
Which end of the oesophagus contains skeletal muscle in its muscularis externa and which end contains smooth muscle
-the mouth (proximal) end of the oesophagus contains mainly smooth muscle
27
Which end of the oesophagus contains smooth muscle in its muscularis externa
-the gastric (distal) end contains mainly smooth muscle
28
What features might be present and different in the distal gastric end of the oesophagus especially below the thoracic diaphragm
- change of epithelium to gastric simple columnar epithelium
- large thin walled veins that can become oesophageal varicosities
- smooth muscle in the muscular externa
29
Give the 4 regions the stomach is divided into
- the cardia
- the fundus
- the body
- the pyloric
30
Which regions of the stomach are similar histologically in respect to their gastric glands
- the fundus
| - the body
31
What are the longitudinal folds of the stomach mucosa called
Rugae
32
Give the epithelium of the stomach
-simple columnar epithelium punctuated by gastric pits where gastric glands drain into
33
Give the layers of the muscularis propria of the stomach
- oblique (innermost)
- circular (inner)
- longitudinal (outer)
34
Give the 3 main types of cell within the glands of the fundus and body of the stomach and what they do
- mucous neck cells - produce lubricatory acid-resistant mucus
- parietal cells - secrete HCI and intrinsic factor
- chief cells - produce pepsinogen
35
What is the difference between the gastric glands of the fundus (and body) of the stomach and the cardia and pylorus of the stomach
Cardia and pylorus
- the cardia and the pylorus of the stomach have gastric glands without parietal or chief cells
- the gastric glands of the cardia and pylorus are shorter and coiled
- the pyloric region also has G cells that produce gastrin and bombesin-like peptide
Fundus and body
- the fundus and body of the stomach contain full gastric glands (all the cells)
- the gastric glands of the fundus and body are longer and straight
36
In which layer of mucosa of the stomach are the gastric glands found
- in the lamina propria
| - at the bottom of the gastric pits
37
What is suggested purpose of the elastic tissue present in the muscularis mucosa of the stomach
- causes collapse of stomach after emptying
| - well developed in carnivores to prevent the perforation of the stomach wall by sharp fragments of bone
38
Which enzyme are numerous in parietal cells
-carbonic anhydrase
39
What does intrinsic factor do
-it is essential for the absorption of vitamin B12
40
Where are parietal cells (also called oxyntic cells) usually found in gastric glands
- under the mucous cells
- but towards the top of the gland
- on top of chief cells
41
What is the normal pH of gastric juice
-pH 2
42
Where are chief cells (also called zymogenic cells) found
- at the bottom of the gastric glands
| - close to the muscularis mucosa
43
What do zymogenic cells do
- also known as chief cells
| - secrete pepsinogen and lipases
44
For which tissue constituent (food) does pepsin have an affinity and what particular benefit does this confer in the process of digestion
- it digests proteins
- has an affinity for collagen
- facilitates breakdown of meat by attacking the connective tissue between muscle fibres
45
Where can G cells be found and what do they do
- in the pyloric region of the stomach
| - they secrete gastrin
46
Give 3 additional types of cells found in all regions of the stomach
- enterochromaffin cells - produce serotonin
- delta cells (D cells) - produce somatostatin
- endocrin cells - vasocactive intestinal peptide (VIP)
47
Which mucosa layer would a lymph node be likely to be found in the stomach
-the lamina propria
48
What are the folds of the small intestine called
-plicae circulares
49
Where are plicae circulares most numerous and least numerous
- most numerous in the jejenum
| - least numerous in the distal part of the colon
50
What epithelium cover the villi
- simple columnar epithelium with two main cell types
| - enterocytes (absorptive cells) and goblet cells (mucus secreting cells)
51
Where are the cells that replace the enterocytes of the villi found
- the crypts of Lieberkuhn next to the villi
| - process takes about 5 days
52
What is each villi made of
- small arteriole
- a thin walled venule
- blind ended lymphatic (lacteal)
- smooth muscle that rhythmically shorten
53
What are the crypts of Lieberkuhn
- contain a stem cell population
- basically the crypts next to each villi
- they are straight tubular glands going downwards
54
How many microvilli does each enterocyte have on its apical surface
- 300
| - they form the brush border
55
What does the glycocalyx on the surface of the microvilli on the enterocytes do
- act as filter
| - anchorage for exo-enzymes
56
How long is the duodenum
12 inches (30cm long)
57
What features help to distinguish the duodenum form other parts of the small intestine and what do they do
- brunner's glands in the submucosa - secrete alkaline mucous that help to neutralise chyme from the stomach
- paneth cells - at the bottom of the crypts and secrete lysozymes which break down bacterial cell walls - they important in regulating bacterial flora of the gut (they have bright pink staining cytoplasm)
-few goblet cells and few plicae circulares
58
What features help to distinguish the jejunum from other parts of the small intestine and what do they do
- no brunner's glands
- no peyer's patches
- many goblet cells, long villi and short crypts
59
What features help to distinguish the ileum from other parts of the small intestine and what do they do
- large peyer's patches in the submucosa erupting into lamina propria
- villi not as tall as jejunum
60
Which of the two layers of smooth muscle that make up the muscularis externa is thicker
-the inner circular layer is 4 to 5 times thicker than the outer longitudinal layer
61
What epithelium lines the vermiform appendix
-simple columnar epithelium with goblet cells
62
Which is not present in the vermiform appendix, the muscularis mucosa or the muscularis externa
-the muscularis mucosa is not present
63
Where do the taenea coli originate from
-the base of the appendix and then run the whole length of the large intestine
64
How does lymphoid tissue change in the appendix from childhood to adulthood
- large amounts of lymphoid tissue present in childhood but it decreases with age
- lymphoid tissue fills the lamina propria and submucos of the appendix
65
There is no intestinal villi in the colon and the lamina propria is restricted in volume due to the packed nature of the crypts, which feature is quite prominent in the colon
- the muscularis mucosa is quite prominent
- the mucosa and submucosa have lots of lymph nodules which are part of the gut-associated lymphoid tissue (GALT) that protects the body from invasion in the gut
66
What epithelium lines the rectum
-simple columnar epithelium
67
What epithelium lines the anal canal
-stratified squamous epithelium that becomes keratinised at the distal end
68
What does the submucosa of the anal canal contain
-plexus of veins that can form anal varicosities
69
What does the peri anal area of the anus contain
- hair follicles
| - modified sebaceous glands
70
Taste buds detect acid, bitter, sweet and salty sensations. How are these distributed across the tongue?-
- Sweet tastes are detected by buds located mainly at the tip of the tongue
- salty tastes on either side towards the front of the tongue
- sour tastes further back
- bitter tastes are detected across the whole of the back of the tongue.
71
Parotid saliva contains immunoglobulins. Where are they produced and what is their function?
Plasma cells resident in the gland produce immunoglobulin A (IgAs). These IgAs are discharged into the saliva where they combine with proteinaceous "secretory pieces" also produced by the glands. These complexes are protected from digestion which allows the IgAs to reach the intestine unmodified.
72
A part of the duct of the parotid gland in known as a striated duct. What gives rises to these striations and with what function can they be associated?
- the striations are the result of deep invaginations of the basal plasmalemma of the cells and large elongated mitochondria that lie perpendicularly between them.
- a similar arrangement of organelles is seen in some of the cells of kidney tubules.
- this pattern is indicative of resorption of water and the transfer of ions across the cells.
- the striated tubules of salivary glands are capable of the secretion and resorption of water and ions from the saliva.
73
What is dental plaque?
It is a calcified deposit rich in dead or dying oral bacteria and food debris.
74
Do the enzymes produced by the salivary glands and swallowed continue to function in the stomach? Briefly explain your answer.
-The salivary enzymes have neutral pH optima and work rapidly in the mouth but they become inactivated by the acid environment of the stomach. However the enzymes continue to act in the stomach within the bolus of food where they are shielded from the gastric juices, until such time as the bolus is dispersed
75
The glands of the pyloric region of the stomach secrete gastrin. What is its function and what other cells of the stomach does it influence?
- Gastrin produced by endocrine secreting cells in the pyloric region of the stomach and in the duodenum
- promotes the secretion of HCl by the parietal cells of the body and fundus of the stomach.
76
Briefly, how and by what route are triglycerides mainly absorbed from the gut?
- although some triglycerides are absorbed into the capillaries of the intestine most are broken down into monoglycerides and fatty acids before being absorbed by the enterocytes.
- once taken up they are reconstituted and combined with proteins before being secreted through their baso-lateral membranes as macromolecular chylomicrons.
- these are then are taken up by lacteals and transported to the blood stream via lymphatics, ultimately finding their way to the liver by a somewhat circuitous route.
77
The gut has an intrinsic innervation consisting of a network of interconnecting nerves and ganglion cells. There are two main parts to this network. Where are they located in the wall of the gut and what names are given to these two main parts?
- there are two main subdivisions to the enteric nervous system.
- a plexus of nerves within the submucosa of the gut known as Meissner's plexus regulates the mucosa and the processes of absorption and secretion
- a second interconnected plexus between the layers of muscle that make up the muscularis externa, known as Auerbach’s plexus regulates much of the contractile activity of the gut.
78
Soon after birth a baby acquires immunity through the acquisition of immunoglobulins provided by the mother's milk. What structural features of the gut allow the uptake of these macromolecules and to what extent are the immunoglobulins digested by the enzymes of the gut?
- the enterocytes of the gut have specific receptor complexes that allow the uptake (undigested) of certain immunoglobulins that subsequently form part of the system of passive immunity.
- this system is at its most active in the neonate in response to immunoglobulins in the mother's first milk (colostrum) but declines in significance within a few months.
79
What does the oral cavity do
- receives food
- chews food
- starts digestion
80
What does carcinoma mean
-a cancer arising in the epithelial tissue of the skin or the lining of the internal organs
81
What do salivary glands do
- produce saliva
| - produce ezymes
82
What is sjorgen's syndrome
- autoimmune disease of the salivary glands
- salivary glands are attached and destroyed by lymphocytes
- no saliva
83
What is hirschsprung's disease
- lack of auerbach's plexus which usually cause movement of food along bowel
- no movement of food
84
What are the interstitial cells of cajal and what is their significance
- in the muscular wall of the bowel
- pacemaker cells that give the pace of contraction of the muscles of the bowel
-prone to tumours (gastrointestinal stromal tumour or GIST) from a mutation in the C-kit gene
85
Give the order of cells from paneth cells ascending to the villi
- transit cells
- potential stem cells
- stem cells
- paneth cells
86
What are giardia lamblia
-parasites that sit on top of the intestinal mucosa and cause malabsorption because it takes nutrients from the host
87
What is ulcerative colitis
- inflammation of the colon
| - that only affects the mucosa of the colon
88
Where is vitamin B12 absorbed
-in the terminal ileum
89
Where does the auerbach plexus lie
-in the muscularis propria between the inner circular and outer longitudinal muscle
90
What unique feature about the histology of the oesophagus helps to confirm its identity
- mucosal glands with squamous lined ducts in the submucosa
| - lymphoid tissue in the submucosa
91
Give the histology of the posterior 1/3 of the tongue
-stratified squamous epithelium overlying waldeyer's ring which has lymphoid tissue
92
What is faecal immunochemical testing
- FIT stands for Faecal Immunochemical Test.
- it is a type of faecal occult blood test which uses antibodies that specifically recognise human haemoglobin (Hb).
- it is used to detect, and can quantify, the amount of human blood in a single stool sample.
- an abnormal result suggests that there may be bleeding within the gastrointestinal tract that requires further investigation.
- those with an abnormal result are then invited for further testing via a colonoscopy.
93
What is epistemology
Epistemology involves knowledge claims and what we can assert about the world around us and the limits of what can be known.
94
What is the difference between the two stances of epistemology, positivism and interpretivism
Positivism is about explanation (need for statistical generalisation etc)
•Interpretivism is about exploring and understanding (need for depth and context etc) – Weber’s Verstehen and ‘meaningful understanding’
95
Is qualitative research a positivistic or interpretivism stance of epistemology
Qualitative research is linked to non-positivistic views about knowledge.
96
What is methodology
Methodology is the study of methods and refers to the strategy or approach to research.
Generally thought of in terms of either:
•Quantitative
•Qualitative
97
What is a method
Method is a specific technique (or set of techniques) for data collection
•Informed by methodology (which is shaped by epistemology)
•Within quantitative methodology – questionnaire survey, experiment etc
•Within qualitative methodology – interviews, observation, documentary analysis
98
What is positivism? (In terms of qualitative research)
Positivism is based on concepts such as:
•objectivity (i.e. the objective reality of the physical, external world)
•scientific method
•Empiricism
Positivism is about explanation (need for statistical generalisation etc)
post-positivism emerged, retaining scientific method but offering, as in the work of Popper, the idea of testable hypotheses / empirical falsification.
99
What is interpretivism
Interpretivism is about exploring and understanding (need for depth and context etc) – Weber’s Verstehen and ‘meaningful understanding’
Not a single philosophical approach but linked to several:
•Hermeneutics – interpreting unique human activity
• Phenomenology – how individuals experience the world
- the assumption is that social reality can only be understood through social constructions such as language, consciousness and shared meanings and understandings.
- interpretive research does not predefine variables, but explores human sense-making in naturalistic settings.
- often explicitly attempts to explore action / behaviour from the point of view of those being research (ie. not imposing a view / set of questions / assumptions on the group being researched).
100
What is Hermeneutics
- interpreting unique human activity
101
What is Phenomenology
how individuals experience the world
102
Which form of epistemology research does quantitative research belong to
-based on positivism
Quantitative methodology
•Emphasises quantification in collection and analysis of data
•Deductive approach – theory testing
•Based on positivism
•Views social reality as external and objective
103
Which form of epistemology research does qualitative research belong to
-based on interpretivism
Qualitative methodology
•Emphasising words, rather than numbers
•Inductive approach – generating theories (does not claim ‘truth’ status)
•Based on interpretivism – understanding the ways in which individuals and groups interpret their world
104
Give the 4 characteristics of qualitative research
- natural context
- non manipulative
- researcher as an instrument as they interpret it
- subjectivity and reflexivity of the researcher
Natural context – occurs in ‘natural’ settings
•Places where people interact (GP/dental surgery, classroom, street corner etc)
•Study of inanimate objects (how health care/policy is developed or organised)
•Non-manipulative – study situations/objects ‘intact’
•Researcher observes, interviews, records, describes settings ‘as they are’
•Researcher as ‘instrument’ – researchers engages in a situation and attempts to make sense of it
•Data collected through human observation
•Data interpretation through human perceptions
•‘Subjectivity’ / reflexivity of researcher – insights, experiences, perceptions of researcher are important part of the study
105
Give the 6 types of analysis of qualitative research
- narrative ;states context of accounts given is just as important as how and why stories are told, analysis often imposes structure and temporality e.g Labovian analysis, Reissman and plot
- interpretative phenomenological analysis (IPA) ; emphasis is on the lived experience of the participants and seeks depth of meaning of them
- grounded theory ;inductive analysis that seeks to generate new from rigorous series of coding stages and processes (constant comparison, open/axial coding, deviant case analysis)
- conversation ;recognises fundamental linguistic importance to interactions and need to analyse different forms of these
- thematic ;5 stages process of understanding data and then moving from codes to themes
- framework ;deductive analysis often relying on pre-determined aims and requirements. Emphasises transparency ability to multiple code
106
What are the functions of the stomach
- store and mix food
- dissolved and continue digestion
- kill microbes
- secretes proteases
- secretes intrinsic factor
- activate proteases
- lubrication
- mucosal protection
- regulate emptying into duodenum
107
Which parts of the stomach is gastrin secreted
- the anthrum of the stomach
| - the enteroendocrine cells secrete gastrin
108
How much gastric acid (HCl) is secreted each day
- approx 2 litres
- requires energy
- by parietal cells
109
How is gastric acid secretion regulated
-by the stomach, brain and duodenum
1 parasympathetic neurotransmitter (ach +)
1 hormone (gastrin +)
2 paracrine factors (histamine +, somatostatin -)
2 enterogastrones (secretin -, CCK-)
110
Give the different phases involved with gastric acid secretion
Turning it on
- cephalic phase
- gastric phase
- proteins in stomach
Turning it off
- gastric phase
- intestinal phase
111
Explain the cephalic phase of gastric acid secretion
- the sight, smell, taste and chewing of food
- activates the parasympathetic system causing the release of acetylcholine
- acetylcholine acts directly on parietal cells causing release of HCl
- acetylcholine triggers the release of gastrin and histamine which act on parietal cells causing the release of HCl
112
Explain the turning on gastric phase of gastric seceretion
- food in the stomach causes gastric distension
- the presence of peptides and amino acids causing release of gastrin
- gastrin causes release of histamines
- gastrin and histamine act directly on parietal cells causing release of HCl
- protein in the stomach act as a buffer and mop up H+ ions increasing the pH
- increase in pH causes decreased secretion of somatostatin and so more parietal cell activity so more HCl
113
Explain the turning off phase of gastric acid secretion
- low pH in the stomach (high H+ ions) inhibits gastrin secretion
- this inhibits histamine release as no gastrin
- low pH stimulates somatostatin release which inhibits parietal cells activity
114
Explain the turning off intestinal phase of gastric acid secretion
- short and long neural pathways reduce release acetylcholine release
- duodenal distension, low duodenal pH, hypertonic duodenal contents and the presence of amino acids and fatty acids cause the release of enterogastrones
enterogastrones include
- secretin which inhibits gastrin release and promotes somatostatin release
- cholecystokinin (CCK)
115
What is an ulcer
-a breach in a mucosal surface
116
Give 4 causes of ulcers
- helicobacter pylori infection
- drugs (non steroidal antiinflammatory drugs NSAIDS)
- chemical irritants -alcohol and bile salts
- gastrinoma
117
How does the gastric mucosa defend itself
- alkaline mucus
- tight junctions between epithelial cells
- replacement of damaged cells
- feedback loops
118
What does gastrin do and which cells secretes it
- it triggers the release of histamine
- it acts directly on parietal cells causing the release of HCl
- acts on gastrin receptors on parietal cells
- it is secreted by enteroendocrine cells (G cells)
119
What does somatostatin do and which cells secretes it
- it inhibits parietal cells from releasing HCl
| - produced by D cells (delta cells)
120
What does histamine do in gastric acid secretion and which cells secretes it
- it acts on parietal cells to cause the secretion of HCl
- it acts on the H2 receptors on parietal cells
- it is secreted by enterochromaffin-like cells (ECL)
121
What does secretin do and which cells secretes it
- regulates water homeostasis
- inhibits gastric acid production
- produced by S cells in the duodenum (and sometimes jejunum)
122
How does helicobacter pylori cause peptic ulcers
- it lives in gastric mucus
- it secretes urease which divides urea into CO2 and ammonia
- ammonia combines with H+ in stomach to form ammonium which damages gastric epithelium
- damage causes an inflammatory respond which further reduces mucosal defense
-ammonium, secreted proteases, phopholipases and vacuolating cytotoxin A all also damage gastric epithelium
123
How do non steroidal anti inflammatory drugs (NSAIDS) cause peptic ulcers
- mucus secretion is stimulated by prostaglandins
- cyclo-oxygenase 1 (COX1) is needed for prostaglandin synthesis
- non steroidal anti inflammatory drugs inhibit cyclo-oxygenase 1 (COX-1)
- so there is reduced mucosal defence so ulcers can form
124
How can bile salts cause peptic ulcers
- a duodeno-gastric reflux can cause regurgitated bile in the stomach
- the bile can strip away the mucus layer
- so a reduced mucosal defence
125
How would a helicobacter pylori infection be treated
with triple therapy
- proton pump inhibitor (to reduce H+ in stomach) e.g omeprazole, lansoprazole, esomeprazole
- antibiotics (to kill bacteria) e.g clarithromycin, amoxillin, tetracycline, metronidazole
- non steroidal anti inflammatory drugs (prostaglandin analogues) e.g misoprostol
126
What do H2 receptor antagonists do and give two examples of them
- they prevent histamine binding to the H2 receptors on parietal cells
- cimetidine and ranitidine
127
Since pepsin is only active at low pH preferentially pH 2, can it be reactivated in the small intestine
-irreversible inactivation in the small intestine by HCO3-
128
How is pepsin produced
- pepsinogen is released by chief cells
- pepsinogen is converted by HCl into pepsin
- pepsin also converts pepsinogen into pepsin too
- optimal pH is 2 or lower
- conversion of pepsinogen to pepsin is pH dependent
129
Is pepsin essential for protein digestion
- no
- protein digestion can occur if the stomach is removed
- it accounts for only 20% of total protein digestion
130
How much of total protein digestion does pepsin account for
-20%
131
What does pepsin do
-breaks down collagen in meat and helps shred meat into smaller pieces increasing surface area for digestion
132
What is the volume of an empty stomach
-50ml
133
Which parts of the stomach undergo receptive relaxation
-the smooth muscle in the body and fundus of the stomach
134
What is receptive relaxation
- mediated by the parasympathetic nervous system acting on the enteric nervous system
- through the afferent input of the vagus nerve
- nitric oxide and serotonin released by the enteric nerves also encourage relaxation
135
Describe the process of gastric motility
-peristaltic waves begin in the gastric body (weak contraction of the body)
-more powerful contraction in the gastric anthrum
-pylorus closes as the peristaltic wave reaches it
-little chyme enters the duodenum
-anthral chyme forced back towards the body of the stomach
-
136
What is the basic electrical rhythm for the stomach muscle contraction
- 3 per minute
- determined by interstitial cells of cajal in the muscularis propria
- depolarisation waves transmitted through gap junctions to adjacent smooth muscle cells
137
What increases the strength of peristaltic contractions
- gastrin
| - gastric distension (mediated by mechanoreceptors)
138
What decreases the strength of peristaltic gastric contractions
- duodenal distension
- increased duodenal luminal fat
- increased duodenal osmolarity
- decreased duodenal pH
- increased sympathetic nervous system action
- decreased parasympathetic nervous system action
139
What happens if the capacity of the stomach is greater than the capacity of the duodenum
- dumping syndrome
- caused by the overfilling of the duodenum with a hypertonic solution
- symptoms are vomiting, bloating, cramps, diarrhoea, dizziness, fatigue, weakness, sweating and dizzness
140
Do secretions of enterogastrones increase or decrease gastric emptying
- decrease gastric emptying
- increase in secretion of enterogastrones is due to duodenal distension, decrease of duodenal pH and other duodenal factors that show food is in the duodenal so this would signal the stomach to not empty anymore into the duodenum
141
What is gastroparesis
-delayed gastric emptying
142
What can cause gastroparesis
- idiopathic
- autonomic neuroathies (e.g Diabetes mellitus)
- abdominal surgery
- parkinson's disease
- multiple sclerosis
- scleroderm
- amyloidosis
- female gender
- drugs
143
What are the symptoms of gastroparesis
- nausea
- early satiety
- vomiting undigested food
- GORD
- abdo pain/bloating
- anorexia
144
Give some drugs that can cause gastroparesis
Gastrointestinal agents
- aluminium hydroxide antacids
- H2 receptors antagonists
- proton pump inhibitors
- sucralfate
Anticholinergic medications
- diphenhydramine (Benadryl)
- opioid analgesics
- tricyclic antidepressants
Miscellaneous
- beta-adrenergic receptor agonists
- calcium channel blockers
- interferon alpha
- levodopa
145
Is gastric motility and emptying regulated by the same factors that regulate HCl production
Yes
146
What is Meckel's diverticulum
- a remnant of the embryonic attachment of the midgut loop to the yolk sac
- usually a blind-ended diverticulum about 1 meter from the end of the ileum
147
Where is Meckel's diverticum
-usually about 1 meter from the end of the ileum
148
How is the superior mesenteric artery related to the duodenum
-the superior mesenteric artery runs over the top of the 3rd part of the duodenum
149
Gives the veins that drain the foregut, midgut and hindgut
Tbc
150
What forms haustrations
-the bulges of the inner circular muscle under the longitudinal muscle that have fused into three taenia coli till the recto-sigmoid junction
151
What does the appendicular artery supply and where is it
- supplies the appendix
| - it runs along the appendix
152
What do the epiploic appendages (appendices epiploicia) signify?
-where blood vessels penetrate the muscles of the bowels to supply the mucosa and submucosa
153
Where does the superior rectal artery run
-enters the pelvic cavity posterior to the rectum and lies in the mesorectum between the rectum and sacrum
154
Do peyer's patches have a capsule
No
155
What does the liver do
- detoxification (filters and cleans blood of waste products)
- immune functions (fights infections and diseases)
- synthesis of clotting factors proteins, enzymes, glycogen and fats
- production of bile and breakdown of bilirubin
- energy storage (glycogen and fats)
- regulation of fat metabolism
- ability to regenerate
156
What are lipids
- esters of fatty acids and glycerol or other compounds (cholesterol)
- naturally occurring organic compounds that are insoluble in water
157
Difference between saturated and unsaturated fats
Saturated
- line up close together
- esters are solid at room temperature
Unsaturated
- less tightly packed
- esters are usually liquid (oils) at room temperature
158
What are the nerve spinal roots for the heart and lungs
-T1 to T5
159
What are the 5 stages of the development of the gut tube
- elongation
- physiological herniation
- rotation
- retraction
- fixation
160
What are the fixed parts of the abdomen
- duodenum (except for the first 1cm)
- ascending colon
- descending colon
- rectum
161
What are the mobile parts of the abdomen
- stomach
- jejunum and ileum
- appendix (caecum)
- transverse colon
- sigmoid colon
162
How many layers of peritoneum form the greater omentum
4 layers - 2 layers folded on each other
163
What is the nervous innervation for the nasopharynx
-the maxillary branch of the trigeminal nerve
164
What is the nervous innervation for the oropharynx
-the glossopharyngeal nerve
165
What is the nervous innervation for the laryngopharynx
-the vagus nerve
166
Give the function of saliva
- lubrication for mastication, swallowing and speech
- oral hygiene (wash and immunity)
- acts as a bicarbonate/carbonate buffer system for rapid neutralisation of acids
- contains digestive enzymes
167
What is the pH of saliva
-pH 7.2
168
What is the pH range of saliva
6.2 to 7.4
169
What is the daily salivary secretion
800 to 1500ml in adults per day
170
What is flow rate of saliva
0.3 to 7ml per minute
171
What factors affect the amount and composition of saliva produced
- flow rate
- circadian rhythm
- type and size of the gland
- duration and type of stimulus
- diet
- drugs
- age
- gender
172
What defences does the mouth have against infection
- mucosa (forms a physical barrier)
- salivary glands (saliva washes away food particles that bacteria and virus might use for metabolic support
- palatine tonsils (immune surveillance and resistance to infection)
173
Which salivary glands are continuously active
- the submandibular, sublingual and minor glands
| - the parotid gland is only active when stimulated and becomes the main saliva producer
174
What is saliva made up of
- salivary gland secretions
- blood
- oral tissues
- microorganisms
- food remnants
175
What are exosomes
- durable, cells-specific lipid microvesicles
- can move through vasculature (blood vessels)
- can be found in urine, blood, breast milk, bronchial lavage fluid, CSF and saliva
176
What are the two main cell types in intralobular ducts of salivary glands and what they do
```
Intercalated ducts (cuboidal)
Striated ducts - major site for reabsorption of NaCl by active transport of HCO3 into the duct lumen
```
-the duct as a whole ends up secreting K+ and HCO3- and reabsorb Na+ and Cl-
177
What are the two paths of protein secretion in salivary glands
Regulated - across apical surface and leads to saliva (main type)
Constitutive - across basolateral membrane and leads to interstitium and bloodstream
178
What percentage of the total mouth saliva do the parotid, submandibular and sublingual glands produce
80%
179
Where are the minor glands of the mouth located
- lips
- cheeks
- hard and soft palate
180
What is the duct of the parotid gland called
Stenson's duct
181
Which structures pass through the facial nerve
- external carotid artery
- retromandibular vein
- facial nerve
182
How many layers of peritoneum form the greater omentum
4 layers - 2 layers folded on each other
183
What do the hepatocytes do
- the creation and storage of energy in the form of glycogen and fats
- the synthesis and secretion plasma proteins
- the deamination of amino acids and the production of urea
- the uptake, synthesis and excretion of bilirubin and bile acids
- the detoxification and inactivation of drugs and toxins by oxidation, methylation or conjugation
184
Describe liver lobules and the blood supply bath the cord of liver cells
- liver lobules are polygonal in shape and centred on the central vein
- hepatocytes are joined together in cords
- separating the cords are sinusoids (wide thin walled fenestrated capillaries) that carry 70% venous blood and 30% arterial blood
185
What is sinusoids and where are they found
-wide thin walled fenestrated capillaries that carry 70% venous blood and 30% arterial blood
186
What structures are in the corners of each liver lobule
- portal triad
- small muscular arteriole carrying oxygenated blood from the hepatic artery
- thin walled vein carrying deoxygenated but nutrient rich blood from the intestine
- bile ductule that carries bile away from the hepatocytes to the gallbladder and bile duct
187
Describe the functional and structural units of liver
Liver lobule - hexagonal with central vein (venous drainage)
| Liver acini - diamond with central portal triad (arterial supply)
188
What are bile canaliculi and how do they relate to the bile ductules
- bile canaliculi are extra-cellular channels between hepatocytes into which the hepatocytes secrete bile.
- these channels coalesce at the edges of the liver lobules and drain the bile into bile ductules that form part of the portal triad.
189
Do liver cells divide
-yes, bi-nucleate cells (dividing cells) make up 2 to 3% of liver mass
190
Which collagen fibres are at the base of sinusoids
-reticulin (collagen 3 fibres)
191
Which space separates hepatocytes from sinusoids
-space of Disse
192
Which structures are in the sinusoids
- ito cells
| - fixed macrophages (Kupffer cells)
193
What are ito cells and give their pathological significance
- ito cells lie in the sinusoids (peri sinusoidal space) of the liver
- they are fat storing cells that are involved in fatty degeneration and fibrosis of the liver in conditions like cirrhosis of the liver
- they are also stem cells of the liver
194
From what circulating blood cell type are Kupffer cells derived? Give an example too of another differentiated cell type that originates from the same cell line.
- Kupffer cells are macrophages that like tissue histiocytes (tissue macrophages) are derived from circulating monocytes.
- Osteoclasts in bone are also derived from the same source
195
If a patient with iron overload (haemochromatosis) (or liver with haemosiderin) has a liver biospy that is stained with perls stain, what colour would the kupffer cells be
-blue/black
196
What do kupffer cells do
- phagocytose and destroy many blood borne pathogens that pass through the liver
- responsible (in part) for production of bilirubin that is taken up and excreted by hepatocytes
197
What are the smooth and rough endoplasmic reticulum most associated with
- rough endoplasmic reticulum - synthesis of plasma proteins
| - smooth endoplasmic reticulum - enzymes of inactivation of drugs and toxins
198
On an electron microscope, what are the rosette like features seen in hepatocytes
-glycogen particles
199
Which epithelium lines the gall bladder
- simple columnar epithelium
| - with poorly developed brush border
200
Which epithelium lines the biliary tree
-simple (to stratified) cuboidal epithelium
201
What does the gall bladder do
- store bile
| - re-absorption of water and salts to concentrate bile
202
Which hormone causes the gallbladder to contract and where in particular is this hormone produced
The main hormone involved in cholecystokinin (CCK) that is produced by endocrine cells in the wall of the duodenum and released in response to fat arriving in the duodenum from the stomach.
203
What kind of gland (serous or mucous) is the pancreas and what part of the pancreas cells are the digestive enzymes packages
- serous
| - in the upper part (apex) of each cell
204
Which cells produce the alkaline fluid released with secretin stimulation for duodenal digestion
-produced by centro-acinar cells and small duct cells in the pancreas
205
Where are the hormones synthesised that cause the exocrine pancreas to secrete?
-mainly in the wall of the duodenum. But the pancreas also receives secretor-motor fibres from the Vagus (Cranial X) nerve.
206
Why are pacinian corpuscles found in the pancreas
-they are pressure sensors normally found in the dermis of the skin although they are a regular feature of the pancreas. Their role in the pancreas is not well understood.
207
What do the islets of langerhans do(or contain)
-they contain endocrine cells including beta cells that produce insulin
208
Some of the blood entering the liver has come directly from the spleen via the splenic branch of the hepatic portal vein. What products in particular is this branch carrying to the liver? And how are these products processed by the liver
-it carries, among other molecules the products of red cell breakdown, most notably iron carrying ferritin.
-ferritin, a protein with an iron core, is discharged by the spleen and is picked up by Kupffer cells in the liver.
209
Hepatocytes store energy in the form of glycogen. Which hormones in particular do you associate with
(a) the breakdown and release of the stores of glycogen and
(b) the promotion of glycogen production from glucose arriving from the gut via the hepatic portal vein?
The liver stores carbohydrate (energy) in the form of glycogen which forms rosettes in the cytoplasm which can be seen easily with an electron microscope.
- glucagon ; glycogen is broken down and released as glucose in response to glucagon a hormone produced by the endocrine pancreas.
- insulin ; it is produced by the pancreas promotes the conversion of excess glucose to glycogen in the liver.
210
Do all hepatocytes take up, store and release glucose equally?
No. They are all potentially capable of storing glucose as glycogen.
- However the hepatocytes at the periphery of the lobules are normally bathed in higher concentrations of glucose than those towards the centre of a lobule and hence are normally more active in this regard.
- Conversely glycogen is removed first from the hepatocytes closer to the centre of a lobule.
211
The liver synthesizes large amounts of protein that it secretes into the blood stream via the space of Disse. Name one of the major proteins that it secretes.
-serum albumin and fibrinogen are perhaps two of the most important proteins continuously synthesized by the liver.
212
Give the 3 surfaces of hepatocytes and the percentage of use
- sinusoidal (70%) - permits exchange of material with blood through space of disse
- canalicular (15%) - permits excretion of bile
- intercellular (15%) - hepatocyte touching another heptocyte
213
What does space of disse (peri sinusoidal space)contain
- ito cells
| - reticulin fibres
214
Through which structures does bile travel from hepatocytes to the bile ducts
-hepatocytes to canaliculi - bile ductules - trabecular ducts - bile ducts
215
Which epithelium layer does the gall bladder not have
-muscularis mucosae
216
Does the exocrine pancreas have a capsule
-a poorly defined fibrous capsule
217
Through which structures do the serous secretions of the exocrine pancreas travel from the centroacinar cells to the main duct
-centroacinar cells to intercalated ducts to interlobular ducts to main pancreatic ducts
218
What is the name of the submandibular duct
-Wharton's duct
219
Which muscle separates the two lobes of the submandibular gland
-the mylohyoid muscle
220
Which salivary glands are found at the superior poles of the tonsils
-weber's gland
221
Which minor salivary glands are found at the base of the tongue and are they serous or mucous
- von Eber's glands underlying the circumvallate papillae
| - they are the only serous minor salivary glands
222
Which tooth surfaces are prone to plaque accumulation
- those adjacents to ducts
- buccal surfaces of the upper molars (parotid duct)
- lingual surfaces of the lower anterior teeth (submandibular duct)
223
Which nerve supplies the parotid gland
-the otic ganglion from the glossopharyngeal nerve
224
Which never supplies the submandibular and sublingual gland
-the submandibular ganglion of the facial nerve
225
What is xerostomia
- dry mouth
| - less than 50% of normal salivary flow
226
What can cause xerostomia
- cystic fibrosis
- sjogren's syndrome
- medication and irradiation of the head and neck cancers
227
Which ions in saliva contribute to salivary caliculi (stones)
- calcium
| - phosphate
228
Which gland has the most cases of duct obstruction (give percentage)
-submandibular gland (80%)
229
Which sites are obstructions most common in the submandibular gland
- blocked duct at the bend of the mylohyoid
| - at the exit of the sublingual papillae
230
Which cells secrete bile
- the hepactocytes in the liver
231
How much bile is secreted per day
500 to 600 mls per day
232
What does CCK (cholecystokinin) do and which cells secrete it
- cells in the duodenum
- cholecystokinin causes the sphincter of Oddi to relax and the gall bladder to contract releasing bile into the duodenum
233
What is the sphincter of Oddi
-major dudodenal papillae
234
What organic molecules and electrolytes are in bile
- bile acids
- phospholipids
- cholesterol
- bile pigments
- HCO3-
- Cl-
- K+
- Na+
- Ca2+
235
What percentage of bile acids have been previously secreted into the intestines (enterohepatic circulation)
95%
236
What are bile acids made from
-cholesterol in pericentral hepatocytes of the acini
237
What are the two types of primary bile acids
- cholic acid
| - chenodeoxycholic acid (water soluble)
238
How does conjugation affect cholic acid and chenodeoxycholic acid
- n-acyl amidated with glycine or taurine
- enhances the hydrophilicity and acid strength of the side chains
- decreases passive diffusion of bile acids across cell membranes during transit through extrahepatic canalliculus
239
What is the pKa of conjugated and unconjugated bile acids
- unconjugated pKa = 5
- conjugated with taurine pKa = 2
- conjugated with glycine pKa = 3.9
240
Give two types of secondary bile acids
- deoxycholic acid
| - lithocholic acid
241
Are bile acids hydrophilic or hydrophobic and what do they do
- they are both (amphipathic)
| - they reduce surface tension and aid emulsification
242
What are the functions of bile acids
- induce bile flow and secretion of biliary lipids (osmotic effect)
- makes lipids soluble by converting into mixed micelles
- facilitates protein absorption
- cholesterol homeostasis
- antimicrobial
243
How does bile acid enter the enterohepatic circulation
- conjugated bile acids remain in intestines
- bile acids actively transported and reabsorbed through apical sodium bile acid transport (ASBT)
- reenters liver through portal circulation
- bile acids taken up by hepatocytes, reconjugated and secreted into bile canaliculi
244
What is the rate limiting enzyme in the bile acid synthesis pathway
-cholesterol 7 alpha-hydroxylase
Which is the same as
-CYP7A1 and cytochrome P450 7A1
245
Give a negative regulator of CYP7A1
-farnesoid X receptor (FXR)
246
What activates FXR (farnesoid X receptor) and supresses CYP7A1
-excess bile acids
247
What is glycogenolysis
-breakdown of glycogen to form glucose
248
What is gluconeogenesis
-breaking down amino acids, lactate and glycerol into glucose
249
What is lipolysis
-breakdown of triglycerides into glucose and ketones
250
Where is iron stored in the body and in what quantity
- liver parenchyma (1,000mg)
| - reticuloendothelial macrophages (600mg)
251
How is iron lost from the body
- sloughed mucosal cell
- desquamation
- menstruation (1 to 2 mg loss per day)
252
What is stored iron called in the body
-ferritin
253
Concentration of ferritin is directly proportional to
-the total iron stores in the body
254
How many atoms of iron does the ferritin contain
-5000
255
What amount of ferritin in the body shows deficiency
- ferritin less than 20ug/ indicates depletion
| - ferritin less than 12ug/L indicates complete absence of stored iron
256
What do vitamins do
- gene activators
- free radical scavengers
- coenzymes or cofactors in metabolic reactions
257
Give examples of water soluble vitamins
- vitamin B and C
| - they pass more regularly through the body so require more regular intake
258
Give examples of fat soluble vitamins
-vitamin A, D, E and K
259
What is the daily requirement of vitamin A
- 0.6mg/day in men
| - 0.7mg/day in women
260
Give the functions of vitamin A
- vision - used to form rhodopsin in the rod cells in the retina
- reproduction
- growth
- stabilisation of cellular membranes
261
What causes vitamin A deficiency and give the clinical features
Cause by fat malabsorption
- night blindness
- blindess
- xeropthalmia
262
Which chemical structure of vitamin D maintains calcium balance in the body
-1,25-dihydroxyvitamin D3
263
Give a source of vitamin D
-sunlight
264
Function of vitamin D
- increased intestinal absorption of calcium
- resorption and formation of bone
- reduced renal excretion of calcium
265
What are the clinical features of vitamin D deficiency
-demineralisation of bone resulting
in rickets in children
in osteomalacia in adults
266
Give the daily requirements of vitamin E
- 4mg/day in men
| - 3mg/day in women
267
What does vitamin E do
-it is an antioxidant
268
Where is vitamin E stored in the body
- non adipose cells such as liver and plasma
| - adipose cells
269
What can cause vitamin E deficiency and give the clinical features
Caused by fat malabsorption (also seen in premature infants )
- retinopathy
- ataxia
- neuropathy
270
Give the 4 sources of vitamin K
K1 - in plants
K2 - by intestinal bacteria
K3 - synthetic
K4 - synthetic
271
What does vitamin K do
- activation of some blood clotting factors
| - necessary for liver synthesis of plasma clotting factors 1972
272
How can the amount of vitamin K be measured
-by measuring the prothrombin time
273
How much vitamin C is needed each day
-40mg/day
274
What does vitamin C do
- collagen synthesis
- antioxidant
- iron absorption
275
Give the clinical features of vitamin C deficiency
- scurvy
- easy bruising and bleeding
- teeth and gum diease
- hair loss
276
What are the active forms of vitamin B12 cobalamins
- methylcobalamin
| - 5-deoxyadenosylcobalamin
277
Where is vitamin B12 stored
-in the liver
278
Where is the intrinsic factor-vitamin B12 complex absorbed
-the terminal ileum
279
Causes of vitamin B12 deficiency
- veganism
| - malabsorption from lack of stomach acid, pancreatic disease and small bowel disease
280
What are the functions of folate
- coenzyme in methylation reactions
- DNA synthesis
- synthesis of methionine from homocysteine
281
What is a clinical feature of folate deficiency
-neural tube defects
282
Give 3 ways that the performance of clotting pathways can be measured
- prothrombin time (PT) extrinsic pathway
- activated partial thromboplastin time (aPTT) intrinsic pathway
- international normalised ratio (INR)
283
What is the normal total bilirubin range
0 to 21 umol/L
284
What is a normal prothrombin time range
9.7 secs to 11.5 secs
285
In xenobiotic metabolism pathways, what occurs in phase 1 and phase 2
Phase 1 - a functional group is added
| Phase 2 - conjugation
286
What are common features of cytochrome P450 enzymes
- present in smooth endoplasmic reticulum (so they are called microsomal enzymes)
- they oxidise the substrate and reduce oxygen
- they have a cytochrome reductase subunit which uses NADPH
- they are inducible
- they generate a reactive free radical compound
287
Which CYP450 enzyme is involved in 50% of all clinically prescribed drugs
-CYP3A4
288
Give an example of an active metabolite being converted to another active metabolite
- codeine to morphine
| - diazepam to oxazepam
289
Give an example of an inactive metabolite being converted to an active metabolite
-desloratadine to loratadine
290
What is another name for paractamol and what is derived from
- acetaminophen
| - derived from para-acetylaminophenol
291
Which enzyme converts paracetamol to harmful intermediates (NAPQ1)
-CYP2E1
292
Where are microsomal enzymes found
- in smooth endoplasmic reticulum
| - in liver then kidney, lungs, intestinal mucosa
293
Examples of microsomal enzymes
-monoxygenoses (CYPs and FMOs)
294
What reactions do microsomal enzymes catalyse
- drug biotransformation reactions
- oxidative, reductive, hydrolytic and glucuronidation
- inducible by drugs and diet
295
Where are non-microsomal enzymes found
-cytoplasm and mitochondria of hepatocytes
296
Examples of non-microsomal enzymes
- protein oxidases
- esterases
- amidases
- conjugases
297
What reactions do non-microsomal enzymes catalyse
- few oxidations and reduction reactions
- hydrolytic reactions
- conjugation reactions except glucuronidation
- not inducible
298
What enzyme is majorly involved in ethanol metabolism
-alcohol dehydrogenase (ADH)
299
Does ethanol need to be conjugated to be excreted
No
300
What are the two routes of ethanol metabolism
- alcohol dehydrogenase
| - microsomal ethanol oxidising system (MEOS)
301
Are cytochrome P450 enzymes inducible
Yes
302
What does the microsomal ethanol oxidising system (MEOS) produce from ethanol
- acetaldehyde
| - a toxic intermediate
303
Can triglycerides diffuse through cell membranes
No
304
What is the rate step of de novo lipogenesis in the liver
- aceyl-CoA to Malonyl-CoA
| - catalysed by Acetyl-CoA carboxylase
305
What is fatty acid synthetase activated and deactivated by
Activated by
- insulin
- substrate (citrate, isocitrate)
Deactivated
- catecholamines
- glucagon
- high fatty acid synthetase inhibits fatty acid synthetase in hepatocyte
306
Give two examples of enzymes that are involved in esterification of cholesterol in lipoproteins
- acyl-CoA:cholesterol acyltransferase
| - lecithin:cholesterol acyltransferase
307
What does de novo lipogenesis in the liver depend on
- insulin concentration
| - sensitivity to insulin
308
Where is apoprotein B (ApoB) 100 synthesised
-in the rough endoplasmatic reticulum (rER)
309
Give the 3 types of fatty acid oxidation in the liver
- peroxysomal B-oxidation
- mitochondrial B-oxidation
- microsomal omega oxidation (CYP4a catalysed)
310
Which enzyme regulates the mitochondrial B-oxidation
-carnitine palmitosyl transferase
311
What inhibits carnitine palmitosyl transferase
-carnitine concentration and malonyl-CoA
312
What length of fatty acid does mitochondrial B-oxidation work on and with how many steps
- various chain length
| - multi step process
313
What length of fatty acid does peroxisomal B oxidation work on and with how many steps
- very long chain fatty acids (more than 20 carbons)
| - 4 step process
314
The five main detoxification roles of peroximal B-oxidation are for
- long chain fatty acids (more than 20 carbons)
- 2 methyl-branched fatty acids
- dicarbolic acids
- prostanoids
- 27 carbon bile acid intermediaries
315
Give 3 transcription factors that fatty acids regulate
- peroxisome proliferator-activated receptors (PPAR a, b, and y)
- retinoid X receptor (RXR)
- sterolregulator element binding protein (SREBP)
316
Which peroxisome proliferator-activated receptor (PPAR) are involved in lipid homeostasis
-all PPAR(s)
317
Which PPAR facilitate energy combustion
-PPAR a, b/d
318
Which PPAR facilitates energy storage
-PPAR y
319
Which PPAR is a lipid sensor for gene transcription
- PPAR a
| - reduced PPAR a sensing (or activity) leads to steatosis
320
Give the stages of liver damage
Fatty liver - deposits of fat causes liver enlargment
Liver fibrosis - scar tissue forms
Cirrhosis - growth of connective tissue destroys liver cells
321
What is hepatic steatosis
-fat content exceeding 5-10% weight of the liver
322
How do fatty hepatocytes lead to steatohepatitis
- apoptosis of fat-laden hepatocyte releases triglyceride and toxic fatty acids
- fatty acids induce CYPE1 and fatty acid oxidation systems
- generation of reactive oxygen species (ROS) resulting in oxidative stress
- oxidative stress induces releases of proinflammatory cytokines from kupffer cells (hepatitis) and ROS (and ethanol) activates stellate cells (fibrogenesis)
323
What is the main source of nitrogen to the body
-dietary protein
324
Where is the main loss of nitrogen from the body
- gut (as urea)
| - kidneys (as urea)
325
Give 2 ways that bodily protein is degradated
- lysosomal dependent pathway
| - ubiquitin (proteasome) dependent pathway
326
Give 4 examples of causes positive nitrogen balance
- pregnancy
- lactation
- bodybuilder + anabolic steroids
- recovery phase
327
Give 6 examples of negative nitrogen balance
- protein malnutrition
- severe illness/sepsis/trauma/burns
- corticosteroids
- cachexia malignancy/ heart failure
- essential amino acid deficiency
- brain injury
328
What enzyme is release by helicobacter pylori and what does it do
- urease
- it splits urea into CO2 and ammonia
- ammonia binds to H+ in the stomach to form ammonium which damages gastric mucosa
329
Give some features of kwashiokor
- oedema
- fatty liver
- dermatoses
330
What are glucogenic amino acids
-carbon backbone producing glucogenic/TCA cycle intermediates
331
What are ketogenic amino acids
-carbon backbone producing acetyl CoA/acetoacetyl CoA
332
Give 2 amino acids that are solely ketogenic
- leucine
| - lysine
333
What is pyridoxal phosphate derived from
-vitamin B6 (pyridoxine)
334
Give the equation of transamination of alanine
Alanine + a-ketoglutatate = pyruvate + glutamate
335
Give the 3 enzymes involved in ubiquitin pathways
- ubiquitin-activating enzyme
- ubiquitin-conjugating enzyme
- ubiquitin-protein ligase
336
What are the effects of secretin and CCK (cholecystokinin) on the stomach
- inhibits gastrin release
| - stimulates stomatostatin release
337
Through what method do enterocytes absorb glucose, galactose and fructose
- glucose and galactose when in high concentration is facilitated diffusion (when in low concentration) is through secondary active transport
- fructose is through facilitated diffusion
338
The presence of what stimulates the release of secretin in the duodenum and what does secretin in turn cause
- acids
| - secretin causes the release of pancreatic bicarbonate secretions
339
The presence of what stimulates the release of cholecystokinin in the duodenum and what do CCK in turn cause
Fats
| Causes the release of pancreatic enzymes and bile
340
What is the difference between folic acid and vitamin B12
-folic acid is vitamin B6
341
What does vitamin B12 do
- keeps the body's nerves and blood cells healthy
- DNA synthesis
- prevents megaloblastic anemia
342
Where are the interstitial cells of cajal found
-in the stomach and in the intestines
343
Is the capacity of the stomach greater than the capacity of the duodenum
-yes
344
How much cholesterol can we get from our diet
-only 10%, the other 90% is made in our bodies
345
When does peripheral fatty acid oxidation occurs
-low insulin and high glucagon
346
What factors can cause non alcoholic steatohepatitis (NASH)
- hepatocyte apoptosis
- oxidative stress
- hepatic inflammation
- adipose tissue inflammation
- gut microbiota
347
Give a cause of fatty liver
- alcohol
| - do the rest of the slide
348
What are muscles and sphincters of the rectum doing when it is empty
- both sphincters are contracted
| - puborectalis muscle is contracted
349
How do we know we need a poo
- rectum fills
- reflex relaxation of internal anal sphincter
- sampling reflex
350
How is defaecation completed
- external sphincter relaxes
- puborectalis relaxes
- rectum contracts
- valsalva maneuver
351
What are the intrinsic nerve supply to the colon
-Meissners and Auberach's plexus
352
What are the extrinsic nerve supply to the colon
- parasympathetic
| - sympathetic
353
How do statins inhibit cholesterol synthesis
-statins inhibit HMG CoA reductase enzyme which is important for cholesterol synthesis
354
How does Ezetimibe inhibit cholesterol transport
-it blocks protein mediated transport of cholesterol across apical surface of enterocytes
355
How are bile acids transported from the terminal ileum to the portal circulation
-actively transported through the apical sodium bile acid transporter (ASBT)
356
How does the farnersoid X receptor lead to inhibit of bile acid production
- bile acid binds to farnersoid X receptor (FXR) in the terminal ileum causing it to produce FGF19
- FGF19 inhibits CYP7A1 (the enzyme that converts cholesterol into bile acids)
357
What is the gastric colic reflex
-stomach stretching and food in the jejunum which leads to mass movement of the colon
358
What forms the external anal sphincter
- the pelvic floor, the external anal sphincter is skeletal muscle and is under voluntary control
- the internal anal sphincter is a continuation of the anal canal (involuntary contro)
359
What does the ductus venosum do
-connects the umbilical vein to the inferior vena cava in a foetus
360
Give 2 glycogen stores in the body
- liver
| - muscle
361
Can the brain store glucose
-no
362
In red blood cells, glucose is converted to
- pyruvate
| - lactose
363
Give two body organs that require a constant supply of glucose
- the brain
| - red blood cells
364
What is ketogenesis
-the liver converts fatty acids to ketones
365
Give 8 hormones that regulate fuel metabolism
- insulin
- glucagon
- cortisol
- adrenaline
- noroadrenaline
- growth hormone
- somatostatin
366
Give 3 processes that insulin promotes
- glycogen storage
- fat storage
- protein synthesis
367
Give 3 processes that glucagon promotes
- glycogenolysis
- gluconeogensis
- ketogenesis
368
Give 4 processes that cortisol promotes
- lipolysis
- glucogenesis
- protein breakdown
- glycogen storage
369
Give a condition associated with cortisol and explain the physiology behind the symptoms
- cushings syndrome
| - tbc
370
Give 3 processes that adrenaline promotes
- Glycogenolysis
- gluconeogenesis
- lipolysis
371
Give 5 processes that thyroxine promotes
- glycolysis
- cholesterol synthesis
- glucose uptake
- protein synthesis
- sensitises tissues to adrenaline
But too much thyroxine is catabolic tho!!
372
Give 5 processes that growth hormone promotes
- gluconeogenesis
- glycogen synthesis
- lipolysis
- protein synthesis
- decreased glucose use
373
What does ghrelin do
- increases before a meal
| - increases appetite
374
What does leptin do in normal weight
-suppresses appetite
375
What does leptin do in obesity
-high leptin levels causes leptin resistance
376
Describe the journey of the embryological pancreas
- the ventral pancreas travels from the front to the back to join the dorsal pancreas
- the ventral pancreas forms the uncinate process
377
What is an impairment
-any loss or abnormality of pyschological, physiological or anatomical structures or function
378
What is a disability
-any restriction or lack (resulting from an impairment) of ability to perform any activity in the manner or within the range considered normal for a human being
379
What is a handicap
-a disadvantage for a given individual that limits or prevents the fulfilment of a role that is normal
380
Give some examples of disability barriers
- negative cultural representation
- inflexible organisational polices, procedures and practices
- segregated social provision
- inaccessible information formats
- inaccessible built environments and products design
381
What is a learning disability
-significant impairment of general cognitive functioning acquired in childhood that is lifelong
382
Approximately how many people in the UK have a lifelong disability
-1.5 million people
383
What does a health inequality mean
-differences in health states between different population groups due to external environment and conditions mainly outside the control of the individual concerned
384
What does the accessible information standard 2016 state
-it is a legal duty to make reasonable adjustments to avoid putting a disabled person at a substantial disadvantage compared with someone who is not disabled
385
How is BMI calculated
-dividing the weight of the patient in kilograms by the square of his or her height in metres
386
What does a Q risk calculation take into account and what does the score mean
- age
- sex
- ratio of total serum cholesterol to high density lipoprotein cholesterol
- blood pressure
- treated hypertension
- diabetes
- smoking status
- ethnicity
- family history of coronary heart disease
- BMI
A score of 20 means a 20% or higher risk of cardiovascular disease over the next 10 years
387
What is Orlistat used for
- only drug in the UK licensed for treatment of obesity in the UK
- usual dose is 120mg, 3 times a day taken with food
- works by reducing fat absorption from the gastrointestinal tract by blocking the action of protein lipase
- the body cannot absorb undigested fat which is passed out in faeces
388
Where does the urea cycle occur
- 2 steps occur in the mitochondria
| - the others in the cytoplasm of the cell
389
What process can all cells in the body convert ammonia and transport it to the liver
- ammonia + glutamate = glutamine
- enzyme = glutamine synthethae
- glutamine travels in the blood to the liver
- in the liver, the enzyme glutaminase converts glutamine back into glutamate and ammonia
