Metabolism Flashcards
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
Chorda tympani
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
V3
Extent of oesophagus
C6–>T10
What muscle is found around the UOS
Cricopharyngeal
Sites of oesophageal constrictions
In the pharynx
Behind aortic arch
Diaphragmatic
3 layers of stomach muscle
Inner oblique
Middle circular
Outer longitudinal
4 parts of duodenum
Superior
Descending
Horizontal
Ascending
Jejunum vs ileum
Jejunum darker 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
Left gastric
Splenic
Common hepatic
Splenic artery branches
Left gastroepiploic
Short gastrics
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
Iliocolic
Right colic
Middle colic
Inferior mesenteric artery branches
Left colic
Sigmoidal
Superior rectal
Falciform ligament
Anterior abdominal wall –> liver
Lesser omentum
Liver –> lesser curvature of the stomach
Greater omentum
Greater curvature of the stomach –> transverse colon
Transverse mesocolon
Transverse colon –> posterior body wall
Mesentery
Small intestine –> posterior body wall
Immune systems in the gut
MALT
Secretory IgA
Gut layers
Mucosa
Submucosa
Muscularis propria
Adventitia
Oesophageal epithelium
Stratified squamous
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 Glycogen phosphorylase 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
Lipogenesis steps
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?
Glucose-6-phosphatase
What enzyme is used to overcome PFK?
Fructuse-1,6-phosphatase
What enzyme is used to overcome pyruvate kinase?
Pyruvate carboxylase
Malate dehydrogenase
PEP carboxykinase
Where does glycerol enter respiration?
Dihydroxyacetone phosphate in glycolysis
Where does glutamine/glutamate enter the TCA cycle?
As a-ketoglutarate
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
McArdle’s disease
Type 5 glycogen storage disease
Deficiency of muscle phosphorylase
Exercise induced fatigue and cramps
Her’s disease
Type 6 glycogen storage disease
Deficiency of liver phosphorylase
Hypoglycaemia
GLUT transporters
GLUT1 - constitutive
GLUT2 - liver and pancreas
GLUT4 - muscle and adipose tissue - controlled by insulin
Hexokinase
Sensitive to feedback inhibition
Wide specificity
Glucokinase
Only in liver and pancreas
Specific to glucose
Not sensitive to feedback inhibition
PFK1 control
Promoted by F2,6P2
Indreictly promoted by high ADP and AMP levels
Inhibited by citrate, high ATP
Where does fructose enter glycolysis?
As fructose-6-phosphate
Converted by hexokinase or fructokinase
What do chylomicrons carry?
Dietary TAGs
What do VLDLs carry?
Liver derived TAGs
What do IDLs carry?
TAGs and cholesterol
What do LDLs carry?
Cholesterol
What do HDLs carry?
Reverse cholesterol transport
Where is apoB48 found?
Chylomicrons
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?
B100, E
What apoproteins do LDLs contain?
B100
What apoproteins do HDLs contain?
AI, AII, C, E
Galactose intolerance
Deficiency of galactose-1-phosphate uridyl transferase
Galactose cannot be converted to glucose in the liver
Accumulation of galactose
Fructose intolerance
Fructose aldolase deficiency
PKU
Deficiency of phenylalanine hydroxylase
No conversion to tyrosine
Maple syrup urine disease
Unable to break down branched amino acids
Build up of keto acids
Sweet urine
MCADD
Can’t break down medium or long chain fatty acids
Familial hypercholesterolaemia
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?
Serotonin, melatonin
What is arginine used to make?
Nitric oxide
What is histadine used to make?
Histamine
What can alanine be converted to by transamination?
Pyruvate
What can glutamate be converted to by transamination?
a-ketoglutarate
What can aspartate be converted to by transamination?
Oxaloacetate
Urea cycle
CO2 + NH4 + ornithine Cabamoyl phosphate Citrulline Arginosuccinate Arginine 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?
Gramicidin
Nigericin
Valinomycin
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
M3 receptors
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
Pancreatic zymogens
Trypsinogen
Chymotrypsinogen
Procarboxypeptidase
Proelastase
What converts trypsinogen?
Enteropeptidase
Active pancreatic enzymes
Glycerol ester hydrolase
Cholesterol ester hydrolase
Phospholipase A2
Bile salts
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
Lipid absorption
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
Amylase Lysozyme Bicarbonate Growth factors Transcoblamin II
Gastric secretions
Mucous Acid Proteases Lipase Intrinsic factor
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
Cephalic phase
Triggered by sight, smell, taste of food
Prepares GI tract by stimulating gastric, salivary, pancreatic and gastrin secretions
Gastric phase
Triggered by stomach distension
Stimulates gastric acid secretion
Intestinal phase
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
Exponential
Graph of solids gastric emptying
Lag period
Then linear
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
Ileal brake
Peptide YY, GLP-1, oxntomodulin
Fats in ileum
Slows gastric emptying and induces satiety
Vomiting centre
Nucleus of the solitary tract
Dorsal motor nucleus of vagus
What communicates with the vomiting centre?
Area postrema
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
Cannabinoid derivatives
New type anti-emetics
5-HT3 receptor antagonists
NK1 receptor antagonists
Corticosteroids as anti-emetics
Anti-inflammatory
Enhances anti-emetic effects of other drugs
Anti-nausea effects