Flashcards in Metabolism Deck (143):
Where does the parotid gland open out?
Opposite the second upper molar
Where does the submandibular gland open out?
Either side of the frenulum
Where does the sublingual gland open out?
Plica sublingualis - fold between tongue and body of the mandible
Nerve supply to the parotid gland
Via auriculo-temporal nerve
Sensory fibres from V3
Parasympathetic fibres from the lesser petrosal nerve from CN IX
Nerve supply to the submandibular and sublingual glands
Derivatives of body and root of the tongue
Body = ectoderm
Root = endoderm
4 extrinsic muscles of the tongue and their innervation
Styloglossus - CN XII - to styloid process
Genioglossus - CN XII - to mandible
Palatoglossus - CN X - to palate
Hypoglossus - CN XII - to hyoid bone
Nerve supply to the anterior 2/3 of the tongue
General sensory = V3
Special sensory = CN VII
Nerve supply to posterior 1/3 of the tongue
General and special sensory = Cn IX
Patch at the root = internal laryngeal CN X
Pharyngeal constrictor muscles
Superior - from medial pterygoid plate
Middle - from angle between hyoid horns
Inferior - from lateral thyroid cartilage
Muscles of mastication and actions
Temporalis - closes mouth
Masseter - closes mouth
Medial pterygoid - closes mouth
Lateral pterygoid - opens mouth
Innervation of muscles of mastication
Extent of oesophagus
What muscle is found around the UOS
Sites of oesophageal constrictions
In the pharynx
Behind aortic arch
3 layers of stomach muscle
4 parts of duodenum
Jejunum vs ileum
Jejunum more vascular
Jejunum more folds
Jejunum thicker walls
Jejunum less fat
Quantity of jejunum vs iluem
Jejunum = 2/5 of gut
Ileum = 3/5
Where is the bare area of the liver?
Superior and posterior surfaces
Arterial arcades in jejunum vs iluem
Longer but fewer in jejunum
More but shorter in ileum
Portal venous system
Splenic and inferior mesenteric veins join
Then join superior mesenteric vein
Forms hepatic portal vein
Coeliac trunk branches
Splenic artery branches
Common hepatic artery branches
Hepatic artery proper --> left and right hepatic, cystic, right gastric
Gastroduodenal --> right gastroepiploic, superior pancreaticoduodenal
Superior mesenteric artery branches
Jejunal and ileal
Inferior mesenteric artery branches
Anterior abdominal wall --> liver
Liver --> lesser curvature of the stomach
Greater curvature of the stomach --> transverse colon
Transverse colon --> posterior body wall
Small intestine --> posterior body wall
Immune systems in the gut
What is secreted by the cardia of the stomach?
Mainly mucous from mucous neck cells
What is secreted by the fundus of the stomach?
Mucous from mucous neck cells
HCL and intrinsic factor from parietal cells
Pepsin from chief cells
Gut hormones from endocrine cells
What is secreted by the pylorus of the stomach?
Mainly mucous from mucous neck cells
Gut hormones from endocrine cells
Cells of intestinal crypts
Enterocyte - secretion of watery intestinal juice
Endocrine cell - regulation of gut function
Stem cell - regeneration of epithelium
Paneth cell - antimicrobial agent release such as lysozyme
Where are Peyer's patches found?
Lamina propria of the ileum
What are taenia coli?
Bands of longitudinal muscle in the colon
Where are Brunner's glands found?
Submucosa of the duodenum
Brunner's gland function
Alkaline mucous secretion for neutralisation of acidic chyme
Which enzyme has a calmodulin subunit that is activated during enzyme and what is its function?
Phosphorylase kinase A
Phosphorylated glycogen phosphatase
Activates glycogen breakdown
What does calcium activate during exercise?
PDC phosphatase to activate PDC to promote entry in TCA cycle
Dehydrogenase enzymes of the TCA cycle
What does AMP do in exercise?
Increases GLUT4 channels
Enzymes at the start of glycolysis
AMPK which turns on PFK2
Inactivates ACC to prevent malonyl CoA formation which would inhibit fatty acid breakdown for energy
What is hormone sensitive lipase controlled by?
Promoted by glucagon and adrenaline
Inhibited by insulin
Process of fatty acid breakdown
Activation by ATP to form fatty acyl CoA
Transport into mitochondria via carnitine shuttle
Beta oxidation to produce acetyl CoA, NADH and FADH2
How is CPT1 (carnitine shuttle) controlled?
Promoted by cAMP and glucagon
Inhibited by malonyl CoA
Formation of malonyl CoA by acetyl CoA carboxylase
Fatty acid synthetase adding 2 carbons at a time
Ketone body formation
acetyl CoA --> acetoacetyl CoA --> HMG CoA --> acetoacetate
Effect on insulin on ketone body production
Insulin inhibits ketone body production by inhibiting HSL and CPTI
Ketoacidosis common in diabetics
What enzyme is used to overcome glucokinase?
What enzyme is used to overcome PFK?
What enzyme is used to overcome pyruvate kinase?
Where does glycerol enter respiration?
Dihydroxyacetone phosphate in glycolysis
Where does glutamine/glutamate enter the TCA cycle?
Hows does alanine enter respiration?
Converted to pyruvate
Primer for glycogen synthesis
Glycogenin - modified tyrosine
Von Giurke's disease
Type I glucogen storage disease
Deficiency of glucose-6-phophatase
Glucose from glycogolysis or gluconeogenesis cannot be exported from the liver
Hypoglycaemia and lactic acidaemia
Type 5 glycogen storage disease
Deficiency of muscle phosphorylase
Exercise induced fatigue and cramps
Type 6 glycogen storage disease
Deficiency of liver phosphorylase
GLUT1 - constitutive
GLUT2 - liver and pancreas
GLUT4 - muscle and adipose tissue - controlled by insulin
Sensitive to feedback inhibition
Only in liver and pancreas
Specific to glucose
Not sensitive to feedback inhibition
Promoted by F2,6P2
Indreictly promoted by high ADP and AMP levels
Inhibited by citrate, high ATP
Where does fructose enter glycolysis?
Converted by hexokinase or fructokinase
What do chylomicrons carry?
What do VLDLs carry?
Liver derived TAGs
What do IDLs carry?
TAGs and cholesterol
What do LDLs carry?
What do HDLs carry?
Reverse cholesterol transport
Where is apoB48 found?
Where is apoB100 found?
VLDLs, IDL, LDLs
What does apoE do?
Controls receptor binding of remnant particles
What does apoC do?
Acts as an enzyme inhibitor of lipoprotein lipase
What apoproteins do chylomicrons contain?
B48, A, C, E
What apoproteins do VLDLs contain?
B100, A, C, E
What apoproteins do IDLs contain?
What apoproteins do LDLs contain?
What apoproteins do HDLs contain?
AI, AII, C, E
Deficiency of galactose-1-phosphate uridyl transferase
Galactose cannot be converted to glucose in the liver
Accumulation of galactose
Fructose aldolase deficiency
Deficiency of phenylalanine hydroxylase
No conversion to tyrosine
Maple syrup urine disease
Unable to break down branched amino acids
Build up of keto acids
Can't break down medium or long chain fatty acids
Reduced number of functional LDL receptors
More LDL in circulation so more cholesterol deposition
What is tyrosine used to make?
Melanin, dopamine, adrenaline, noradrenaline, thyroxine
What is tryptophan used to make?
What is arginine used to make?
What is histadine used to make?
What can alanine be converted to by transamination?
What can glutamate be converted to by transamination?
What can aspartate be converted to by transamination?
CO2 + NH4 + ornithine
Urea + ornithine
Control of PDC
Controlled by feedback inhibition from acetyl CoA and NADH
ETC complex I
NADH --> UQ
ETC complex II
FADH2 --> UQ
Unable to pump proton into IM space
ETC complex II
UQ --> cytochrome C
ETC complex IV
Cytochrome C --> oxygen
What do carbon monoxide and cyanide inhibit?
Complex IV - cytochrome C oxidase
Natural antibiotics that can uncouple?
What does dinitrophenol do?
Can carry H+ ions across membrane
Avoids ATP synthase
What happens to HIF-1 in hypoxia
Beta subunit stabilised
Can bind to regulatory sections of genes
Promotes gene transcription of genes involved in glycogen breakdown and glycolysis
Induces transcription of EPO and VEGF
Promotes mitochondrial autophagy and suppresses fission
Difference in saliva secretions from glands
Parotid = serous and rich in amylase
SubML = serous and mucous rich in proline rich proteins
Control of salivary secretions
Vasoactive intestinal protein
Function of intrinsic factor
Critical for vitamin B12 absorption
Where is gastrin secreted from?
G cells in the antrum
Where is somatostatin secreted from?
D cells in the antrum
What is the action of gastrin
Stimulates parietal cells to secrete acid via CCKB receptors
Stimulates ECL cells to release histamine which stimulates parietal cells via H2 receptors
When is somatostatin released and what does it do?
Released in presence of acid
Inhibits G cells, ECL cells and parietal cells
Where is secretin produced
S cells of the duodenum
What stimulates pepsin release?
Gastrin from G cells
Secretin from duodenal S cells
ACh via M3 receptor
Acid is gastric mucosa
What cleaves pepsinogen to pepsin?
Acid and pepsin
What promotes pancreatic secretions?
VIP and secretin promote secretion of aqueous component
CCK promotes secretion of enzymatic content
Where is CCK released from and when?
From duodenal I cells
In response to fat and peptide presence
What converts trypsinogen?
Active pancreatic enzymes
Glycerol ester hydrolase
Cholesterol ester hydrolase
Synthesised from cholic acid originally from cholesterol
What stimulates bile release?
CCK, ACh, gastrin
Effect of secretin on bile?
Stimulates bicarbonate and water release into bile
Form micelles than can diffuse through membrane
Remade into TAGs by smooth ER
Packaged into chylomicrons
Secreted into IC space
Taken up by lacteals and join lymphatic circulation
Components of saliva
Gastric acid secretion
Carbon dioxide in
Converted to bicarbonate and protons by CA
Bicarbonate pumped out into plasma and exchnaged for Cl-
H+ pumped out by H+/K+ ATPase
Cl- and K+ pumped out into lumen
How H2 receptor activation leads to gastric acid secretion
Activates adenylyl cyclase
ATP --> cAMP
Activates protein kinase
Activates H+/K+ ATPase
Interstitial cells of Cajal
Create rhythm of electrical slow waves
Cause phasic contractions
Migrating motor complexes
3 phases every 90-120 minutes
Create sensation of hunger
Clear undigested material
Prevent bacterial overgrowth
Triggered by sight, smell, taste of food
Prepares GI tract by stimulating gastric, salivary, pancreatic and gastrin secretions
Triggered by stomach distension
Stimulates gastric acid secretion
Triggered by chemoreceptor activation in the small bowel
Inhibits further gastric secretions
Waves of peristalsis in the oesophagus
Primary = occurs on swallowing
Secondary = pushes bolus into stomach
Graph of liquid gastric emptying
Graph of solids gastric emptying
Duodenal and jejunal brake
HCl, LCFAs, AAs, glucose, peptides in these regions
Reduces pyloric sphincter opening
Reduces antral contraction
Enhanced relaxation and storage of fundus
Peptide YY, GLP-1, oxntomodulin
Fats in ileum
Slows gastric emptying and induces satiety
Nucleus of the solitary tract
Dorsal motor nucleus of vagus
What communicates with the vomiting centre?
Motion type anti-emetics
Muscarinic antagonists - hyoscine
Old type anti-emetics
D2 receptor antagonists - act on area postrema to block vomiting induced by blood borne agents
H1 receptor antagonists
New type anti-emetics
5-HT3 receptor antagonists
NK1 receptor antagonists