23/05 Flashcards
what does omeprazole act on
Parietal cells are located in the epithelium lining the fundus and body of the stomach, and secrete HCl into the stomach using the H+/K+-ATPase pump. Omeprazole is a proton pump inhibitor (PPI) and therefore inhibits the H+/K+-ATPase pump.
2 primary bile acids
Cholic acid
Chenodeoxycholic acid
bile salts
cholic acid
Chenodeoxycholic acid
When these bile acids are conjugated with amino acids they form bile salts.
Bile salts are amphipathic which means they have a hydrophobic end (which is lipid soluble) and a hydrophilic end (which is water soluble).
This structure allows bile salts to emulsify fats which allows pancreatic lipase digest fats.
hepatotoxic drug eg
Amiodarone is a hepatotoxic drug. This means it is likely to cause damage to the hepatocytes and impair its ability to conjugate bilirubin, leading to hepatic jaundice.
used for bad ventricular tachy
Metoclopramide
Metoclopramide is a dopamine-receptor antagonist which causes relaxation of the lower oesophageal sphincter and increases gastric motility, leading to increased gastric emptying. Patients on these drugs may experience an increased appetite
Enterogastric reflex
The enterogastric reflex is stimulated by distension of the small intestine by the presence of chyme. Inhibitory signals are sent to the stomach via the enteric nervous system as well as signals to the medulla. Vagal stimulation of the stomach is reduced and gastric acid secretion is reduced.
feedback mechanism to regulate the rate at which partially digested food (chyme) leaves the stomach and enters the small intestine.
Brunner’s gland
Submucosa of the duodenum only
Brunner’s gland provide abundant alkaline mucous to neutralise the chyme entering from the stomach.
Gastric Inhibitory Peptide
Gastric Inhibitory Peptide (GIP) mediates the ileal brake reflex. This delays gastric emptying to prevent unabsorbed nutrients entering the lower ileum, and is mainly triggered by high levels of fat. The aim of the ileal brake reflex is to slow small intestine bolus transit, to increase absorption in the small intestine. If GIP is disrupted, this will therefore exacerbate malabsorption by interrupting this reflex.
What is mainly responsible for gastric-inhibitory peptide (GIP) secretion?
GIP belongs to a family of metabolic hormones called incretins. Incretins are released after eating a meal containing glucose. They cause beta cells of the pancreatic islets to release insulin and lower blood glucose levels.
excess insulin production and secretion continues after the glucose derived from the meal has been digested, causing the amount of glucose in the bloodstream to fall to a lower-than-normal level.
what does CCK do
Chole = “bile”, cysto = “sac”, kinin = “move” –> move the bile-sac (gallbladder).
The presence of fatty acids in chyme that passes through the duodenum stimulates gallbladder contraction and release of stored bile into the duodenum via CCK. Bile plays a key role in digestion of fat in the duodenum.
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Frank-Starling curve of the heart shows
Stroke Volume and Preload
reason for oedema in heart failure?
Aldosterone promotes sodium and anion reabsorption, which increases the osmolality of the extracellular fluid. Thus, osmoreceptors in the hypothalamus detect this increase and stimulate ADH secretion, which acts to increase fluid retention and oedema.
Venous return =
(Mean systemic filling pressure - Right atrial pressure) / Resistance to venous return.
Muscarinic receptors
G-protein coupled receptors. (M1-M5)
M1 is excitatory and found in neural tissue, gastric parietal cells and salivary glands.
M2 is inhibitory and found in cardiac tissue.
M3 is excitatory and is principally found in exocrine and smooth muscle tissue.
Muscarinic receptors are involved in parasympathetic neural pathways, as well as sympathetic stimulation of the sweat glands. They are usually stimulated by acetylcholine (although they can be stimulated by muscarine) and they are inhibited by atropine.
Adrenoceptors
G-protein coupled receptors. sympathetic nervous system
Alpha1, Alpha2, Beta1 and Beta2.
Alpha1 (located in blood vessels and when stimulated cause vasoconstriction),
Beta1 (located in the heart and when stimulated cause increased heart rate and contractility)
Beta2 (located in the lungs and when stimulated cause bronchodilatation).
They are stimulated by adrenaline (typically acts on Beta adrenoceptors) and noradrenaline (typically acts on Alpha adrenoceptors).
Reactive hyperaemia
Reactive hyperaemia describes the vasodilatation and transient increase in blood flow that occurs in response to tissue ischaemia, as occurs in coronary thrombosis. This means that the level of blood flow after vessel occlusion is greater than the level of blood flow prior to the occlusion.
elastic lamina found (perhaps counterintuitively) in muscular arteries only
of which there is an external and external component.
not in arteries , just elastin
A 35 year old patient, who has had asthma for many years, is told that his condition causes some of his alveoli to receive less air than usual.
Which mechanism is the most effective means to correct this V/Q mismatch?
n order to maximise gas exchange, blood is redirected towards regions where there is sufficient ventilation. This allows for gas exchange to be at its most efficient and thus maintain a proper V/Q ratio
vasoconstriction
Pneumothorax and compliance
one-way valve is created in which air can enter the pleural cavity but is unable to leave. This results in the progressive accumulation of air in the pleural cavity. The intrapleural pressure becomes greater than the atmospheric pressure, compressing the ipsilateral lung and reducing its compliance. As a result, the lung collapses and is unable to expand due to the pressure.
pathophysiology of cystic fibrosis?
Cystic fibrosis transmembrane conductance regulator (CFTR) protein is important in the reabsorption of chloride and sodium ions across the surface epithelium. In the sweat glands, loss of CFTR protein causes impaired reabsorption of chloride and sodium ions, resulting in the production of hypertonic sweat.
30%
residual volume
olume of remaining air after a maximal exhalation
How does the calcium-sensing receptor (CaSR) found in the parathyroid gland’s chief cells respond to raised calcium levels?
By inhibiting the release of Parathyroid Hormone (PTH)
Pre-hepatic jaundice
Due to excessive erythrocyte/RBC breakdown, the liver receives too much unconjugated bilirubin and cannot conjugate it all. The liver can only conjugated so much bilirubin until it becomes overwhelmed and the rest seeps into the bloodstream. Unconjugated bilirubin elevated
hepatic jaundice
The actual liver is impaired in a way that its hepatocytes cannot conjugate bilirubin OR there is too much pressure within the liver and conjugated bilirubin becomes trapped within the intra-hepatic ducts. Both conjugated and unconjugated bilirubin elevated
