Week 1 Flashcards
1
Q
What are the three components of the large intestine
A
Caecum, appendix and colon (ascending, transverse, descending)
2
Q
Describe the general structure of the wall of the digestive tract e.g layers and what they contain. Starting from lumen
A
- Mucosa (epithelial cells with exo and endocrine epithelial cells)
A. Lamina propria (loose CT, capillaries, neurones, immune cells)
B. Muscularis mucosae (thin smooth muscle changing shape of mucosae) - Submucosa (CT with nerve network ‘ submucous plexus’)
- Muscularis externa (circular muscle causing contraction of lumen and longitudinal muscle causing shortening of intestine)
- Serosa (CT)
3
Q
What is the function of the musclularis mucosae
A
Upon contraction can cause changes in shape of mucosae and so absorption and secretion of intestine
4
Q
What are slow waves? What are their function
A
Rhythmic patterns of depolarisation and repolarisation
Determine frequency, direction and velocity of smooth muscle contraction hence the rate peristalysis
5
Q
What is the function of the enteric nervous system
A
To regulate the mysenteric plexus’s sphincters and the motility of Gi tract, submucous plexus regulates epithelia and blood vessels
6
Q
What is the migrating motor complex
A
Sweeping contraction from the stomach to the terminal ileum
7
Q
What are the 7 sphincters from superior to inferior
A
Upper oesophageal Lower oesophageal Sphincter of oddi Pyloric Illeocaecal valve Internal sphincter External sphincter
8
Q
Which sphincter controls the entering of pancreatic and bile juices to the duodenum?
A
The sphincter of oddi
9
Q
Name the intermediates required to form glycogen from glucose
A
Glucose Glucose-6-phosphate Glucose-1-phosphate UDP-glucose Glycogen
10
Q
What hormones stimulate production of glycogen?
A
Insulin
11
Q
What hormones inhibit the production of glycogen and stimulate production of glucose?
A
Glucagon
12
Q
What enzymes are acted on by insulin?
A
Stimulates the production of glycogen by stimulatign glycogen kinase
Inhibits glycogen phosphorylase
13
Q
What enzymes are acted on by glucagon
A
Stimulates glycogen phosphalase
Inhibits glycogen synthase
14
Q
Where does the final step of glycogenolysis occur?
A
In the liver, ONLY the liver can dephosphorylate the glucose-6-phosphate
15
Q
Define gluconeogenesis
A
The making of glucose when hepatic stores become depleted, occurs in the liver
16
Q
What are some of the precursors for gluconeogenesis
A
Lactate
Amino acids
Glycerol
17
Q
What is a chylomicron
A
A type of lipoprotein used to transport dietary fat into cells. Composed of tyiglycerides, proteins and phospholipids
18
Q
What does the break down of fats produce?
A
Triglycerides (fats) are broken down to produce glycerol and fatty acids
19
Q
What process needs to occur to fatty acids in order for them to be used for energy?
A
Beta oxidation
20
Q
Where does beta oxidation occur?
A
In the mitochondria
21
Q
What is the likely product balance of beta oxidation?
A
Acetyl-coa, FADH2, NADH + H+, fatty acyl-coa (shortened by 2 carbons)
22
Q
What equation is used to determine how many times beta oxidation is required to completely break down a fatty acid?
A
no. Of carbons/2 (as the fatty acyl-coa is shortened by 2 carbons each cycle)
Then minus 1. E.g C/2 -1
23
Q
What are ketone bodies? Give some examples
A
Acidic molecules produced from the beta oxidation of excessive fats
E.g acetoacetate, bet-hydroxybutyrate and acetone
24
Q
What can ketogenic amino acids be degraded to ?
A
Fatty acids or ketones
25
Can all carbon skeletons of amino acids enter the TCA cycle?
Yes
26
What is the disease alcaptonuria?
The inability to degrade phenylalanine and tyrosine
27
What is maple syrup urine disease?
Inability to degrade valine, isoleucine and leucine
28
What is phenylketonuria
The accumulation of phenylalanine as a result of an inbility to break it down
29
What metabolite is formed directly from the degradation of fatty acids?
Acetyl- coa
30
When does lipogenesis occur?
When we take in an excess of energy so converts the acetyl-coa to fatty acids and triglycerides in the liver
31
What is the rate limiting step in the conversion of acetyl-coA to fatty acids?
First converted to malonyl-coa by acetyl-CoA carboxylase
32
What is the glucose transporter in the liver?
Glut 2
33
What is the glucose transporter in adipose tissue?
GLut 4 which is a sodium glucose symporter
34
What is the role of gut peptides in satiety signalling? (Feeling full)
They feed back to hypothalamus to short term regulate meal frequency and duration
35
What is the role of the hypothalamus
To control energy intake and body weight
36
What part of the hypothalamus is responsible for feeling full and feeling hungry
Fullness= ventromedial
Hungry= lateral hypothalamus
37
What is the peptide hormone that stimualtes food intake
Ghrelin
38
Which peptide hormone stimulates reduction of food intake?
GLP-1 (glucagon like peptide 1)
39
What are the specific hormones that feed back to the hypothalamus to control metabolism?
What do they do?
Leptin; released in proportion to fat intake- if too little released hunger increases
Insulin; again released in proportion to fat intake
These inform brain to alter energy balance e.g eat less burn more
40
What are the two functional areas of the stomach, what do they do?
Body of stomach; involved in storage
Antrum of stomach; breaking down stomach contents
41
What are the structures in the stomach called that allow increased volume intake?
Rugae
42
What factors can repress the stomach from emptying into the duodenum?
If chyme is too acidic (must be ph7)
If chyme too hypertonic (too carbohydrate rich can cause water to be drawn out circulation BAD)
CCK (inhibits stomach contraction)
Gastrically, will only release when there is increased motility in stomach as food small
43
What hormones are secreted from the antrum of the stomach? From what cell? Function?
Somatostatin from a D cell that inhibits HCL secretion (when stomach emptying)
Gastrin from a G cell stimulates HCL secretion (when stomach full)
44
What are the hormones secreted from the fundus and body of the stomach? Cell? Function?
Pepsinogen from chief cell (as most bountiful) inactive precursor of pepsin
HCL from parietal cell that denatures proteins and kills ingested organisms also cleaves pepsinogen to form pepsin.
45
What do all cells produce in the stomach (aside from the specialised ones)? What is its function?
Mucus production, this protects the stomach wall from corrosion so prevents formation of ulcers
46
How is hydrochloric acid produced from a parietal cell?
By the splitting of a H+ ion from bicarbonate which is then excreted from a proton pump (H+/K+ atpase).
This bicarbonate is formed from CO2 and H20 through carbonic anhydrase.
The Cl- is transported through the cell via an antiporter transporting the Hco3- out of the cell, then the cl- is then excreted into the stomach to combine with H+ via a CFTR (problem in cystic fibrosis)
47
What are the two main movements of the temperomandibular joint?
Translation (jaw moving forward in the superior cavity)
| Rotation (moving up and down in teh inferior cavity)
48
What are the four muscles of mastication? Function?
Temporalis mandibular; closing jaw, from temporal fossa to coronoid process
Masseter; smaller muscle from mandibular angle to zygomatic arch (close)
Medial pterygoid; similar to masseter but more internal from mandibular angle to pteryoid plates
Lateral pteryogoid; condyle of mandible to pteryoid plates (OPEN) relates to the TMJ
49
What is the innervation of the muscles of mastication? Where is this nerve located in the brain? Through what foramen?
Trigeminal nerve; mandibular division V3
Through foramen ovale
Connected at the pons
50
Summarise the sensory innervation of the oral cavity
Superiorly innervated by trigeminal nerve V2 maxillary nerve which exits from pons through foramen rotundum
Inferiorly innerated by trigeminal nerve V3 mandibular segment exiting from foramen ovale
51
What are the three glands of the mouth ? Where are they located?
```
Parotid gland (near ear)
Submandinbular gland (beneath mandible)
Sublingual gland (beneath tongue)
```
52
What is the innervation and the excretion of the parotid gland? E.g where excrete into?
Glossopharyngeal nerve (CN IX)attaching to medulla and through the jugular foramen
Through the parotid duct which secretes through the upper 2nd molar e.g 7th tooth
53
What are some common causes for pancreatitis?
GET SMASHED
Gall stones
Ethanol
Trauma
```
Steroids
Mumps
Autoimmune
Scorpion bites
Hyperlipidemia
ERCP (removal of gall stones)
Drugs
```
54
What is nutcracker oesophagus?
Disorder of movement of oesophagus in taht the smooth muscle contracts in a normal sequence but too forcefully or for too long. Results in difficulty swallowing, dysphagia and can cause chest pain. Common in elderly
55
What is achalasia?
Disease of the lower oesophageal body and sphincter that prevents relaxation hence resulting in absent contractions/ peristalsis.
56
What is gluconeogenesis?
Primary source of glucose when overnight hepatic glycogen depleted. E.g the making of new glucose
57
What enzyme catalyses the conversion of glucose into glucose-6-phosphate?
Hexokinase?
58
What enzyme catalyses the conversion of glucose-6-phosphate into glucose-1-phosphate in gluconeogensis?
Phosphoglucomutase
59
What enzyme catalyses the conversion of UDP-glucose into glycogen?
Glycogen synthase
60
What must fatty acids be bound to before they can undergo beta oxidation?
Converted to fatty acyl-coA in the cytoplasm
61
Describe the physiology behind ketone production?
They are derived from acetyl-Coa after beta oxidation in the liver mitochondria. They will diffuse into the blood stream and will then be picked up by tissues and converted back to acetyl CoA. UNLESS
Oxaloacetate (its carrier) has been removed due to starvation as it removes oxaloacetate to make glucose. Hence these ketones remain in the blood stream causing acidosis
62
Why is urea produced? Where does its production occur?
It is the production of the breakdown of ammonium from metabolism of amino acids.
Liver
63
What happens to the acetyl-CoA if we have taken in an excess of energy?
It is converted to fatty acids and triglycerides in the liver (intermediately converted to malonyl-coA by acetyl coA carboxylase).
Then the triglycerides are transported via VLDL to adipose tissue for storage
The fatty acids are bound to albumin and also transported to adipose tissue
64
What part of the hypothalamus is involved with overeating?
Ventromedial hypothalamus
65
What part of the hypothalamus is involved with undereating?
Lateral hypothalamus
66
What is the only drug available for weight loss? How does it work? Side effect?
Orlistat
Inhibits pancreatic lipases so malabsorption
Cramps diarrhoea
67
What is the function of a D cell? What does it secrete and what is its secretory function?
Some dicks stop staring eyes
Somatostatin D cell stop stomach emptying
68
What is the function of a G cell? What does it secrete and what is its secretory function?
Great Grandma sings Hopefully
Gastrin G cell stimulates HCL
69
What is the function of a Chief cell? What does it secrete and what is its secretory function?
People chunder always
Pepsinogen Chief cell autocatalyst
70
What is the function of a enterochromaffin cell? What does it secrete and what is its secretory function?
Humans excite certain sex hormones
Histamine enterochromaffin cell stimulate HCL
71
What is the function of a parietal cell? What does it secrete and what is its secretory function?
Hydrochloric acid parietal cell activates pepsinogen, denatures, kills
Hateful people acquire poison that denatures and kills
72
What is the innervation and the excretion of the submandibular gland? E.g where excrete into?
Secretes via lingual caruncle
CN VII (facial)
73
What is the innervation and the excretion of the sublingual gland? E.g where excrete into?
CNVII (facial)
Several ducts superiorly in the floor or the mouth
74
What nerves innervate the tongue?
Anterior; facial nerve (CN VII) and CN V3 (mandibular trigeminal for taste and sensation
Posterior; glossopharyngeal for taste
Muscles of tongue; hypoglossal nerve and vagus
75
What are the four muscles of the tongue?
Genioglossus
Hypoglossus
Palatoglossus
Syloglossus
76
What nerve innervates the epiglottis to allow its abduction to close? Especially during the gag reflex
Glossopharyngeal
77
What is the vertebral level of the oesophageal sphincter?
C6
78
How many teeth are in the grown adults mouth? How are these numbered?
32
From the left/right incisors being 1 and the wisdom teeth being 8
79
Which enzyme allows the production of oligosaccharides such as lactase? What kind of bonds does it cleave?
Alpha amylase
Alpha-1,4 linkages
80
What are the different types of oligosaccarides?
Lactase
Maltase
Sucrase-isomaltase
81
Where does the breakdown of the oligosaccarides occur?
Intraluminally
82
What do oligosaccharidas cleave to form? What enzyme facilitates this?
Glucose
Fructose
Galactose
Oligosaccharidases
83
What enzyme catalyses the breakdown of lactose to glucose and galactose?
Lactase
84
Female presents with bloating, abdominal pain, flatulence and loose stools with diarrhoea. She mentions this is usually worse after dairy products. Diagnosis?
Lactase deficiency
85
What are some causes of lactase deficiency?
Secondary to UC, crohns, gastroenteritis,
Primary congenital
86
By which carrier is glucose transported into the apical membrane of intestinal cells?
SGLT1
Sodium glucose co-transporter
87
By which carrier is glucose transported out of the basal membrane of intestinal cells?
GLUT 2 facilitated diffusion
88
What are oligosaccharides?
Complexes made of monosaccharides like glucose or fructose
89
Waht are oligopeptides?
Peptides e.g composed of 2-6 amino acids
90
Give some examples of endopeptides that cleave peptide bonds in oligopeptides
Trypsin
Chymotrypsin
Elastase
Pepsin
91
By which carrier are amino acids transported into the enterocytes?
Secondary active transport mediated by sodium dependent transporters
92
What transporter allows movement of oligopeptides across the apical membrane of the enterocyte
PepT1
93
What are the muscles of the anterolateral abdominal wall? What is their orientation?
Rectus abdominus; vertical
External oblique; hands in front pockets
Internal oblique; hands on chest
Transversus abdominus; horizontal plane
94
What are the attachements o the greater omentum?
Greater curvature of stomach and transverse colon
95
What is contained within the portal triad?
Hepatic portal vein
Hepatic artery
Bile duct
96
Patient presents with a dull, achy, nauseating, poorly localised pain in the epigastric region. What type of pain are they describing?
Visceral pain
97
Patient presents with sharp, stabbing, localised pain. What type of pain is this?
Somatic pain
98
What is the sympathetic vertebral level of the foregut organs? What do these include
T6-T9
```
Oesophagus
Spleen
Liver
Gall bladder
1/2 pancreas
```
99
What is the sympathetic vertebral level of the midgut organs? What do these include
T8-T12
Mid-duodenum
2/3 transverse colon
1/2 pancreas
100
What is the sympathetic vertebral level of the hindgut organs? What do these include
T10-L2
Transverse colon last 1/3
Anal canal
101
Where does foregut pain present?
Epigastric region
102
Where does midgut pain present
Umbilical region
103
Where does hindgut pain present?
Pubic region
104
What is the innervation of the anterolateral abdominal wall?
The thoracoabdominal nerves present from the 7th to 11th intercostal nerves
105
Which part of the digestive tract is involved with the absorption of vitamin B12?
Jejunum
106
What is the function of an I cell? What does it secrete and what is its secretory function?
CCK I cell stimulates digestion by enzymes release, inhibits MMC
Crazy iona sings disgracefully by evading reason, incredibly moronic
107
What is the function of a S cell? What does it secrete and what is its secretory function?
Secretin S cell stimulates liver and pancreas secretion into duodenum
Some say smelling lilies and pansys stimulates incredible dancing
108
What is the function of motilin? Where secreted from and what is its secretory function?
Motilin M cell triggers MMC in duodenum and jejunum
Mom must try to move into dundee and juggle
109
What enzymes stimulate the MMC?
Motilin
110
What enzymes inhihbit the MMC during the fasting state?
Gastrin G cell
| CCK I cell
111
What is the cephalic stage of digestion?
Before food enters the GI tract, controlled by vagal stimulation by acinar cells. This stimulates release of histamine and HCL in the stomach
112
What is the gastric stage of digestion?
After you swallow food, causing distention of the stomach resulting in stimulation of the stretch receptors causing release of gastrin
113
Where is sucrose digested into glucose and fructose?
At the brush border of the intestines
