hllj/quesmed huggingface dataset:
Which of the following statements only applies to smooth muscle cells?

Options:
explanation: Smooth muscle cells are fusiform cells, typically 200-300um long. In contrast, skeletal muscle cells can be much longer, spanning the entire distance of muscles. For example, skeletal muscle cells in the sartorius (the longest muscle in the body, spanning from the ASIS to Pes anserinus) can reach up to 600mm in length.
name: The cells can reach up to 600mm in length
label: d
answer: no
explanation: Although smooth muscle cells do allow calcium entry from the extracellular space, cardiac muscle also allows this through dihydropyridine receptors. The difference is that the sources of calcium entry into the cytoplasm are much more varied in smooth muscle, and are under both neurotransmitter and hormonal control for the tight regulation of contraction in different situations.
name: Allow calcium entry from the extracellular space
label: c
answer: no
explanation: Smooth muscle is the only type of muscle that does not contain sarcomeres. In cardiac and skeletal muscle, there are: linear Z-discs at either end of each sarcolemma to which actin connects; I bands in which there is actin and titin to anchor myosin but no myosin itself; A bands where actin and myosin overlap; and central M bands in which there is myosin but no actin. These structures can be seen on transmission electron microscopy.
name: Contain sarcomeres
label: b
answer: no
explanation: Smooth muscle cells are typically stimulated to relax by nitric oxide. This occurs because nitric oxide activates soluble guanylate cyclases, generating cGMP which activates PKG. Amongst other functions, PKG lays down inhibitory phosphorylation marks on MLCK, reducing the phosphorylation of myosin, and subsequently reducing contraction.

<br>
name: Contraction stimulated by nitric oxide
label: e
answer: no
explanation: Smooth muscles are called smooth due to the lack of striations visible on microscopy. This is because actin and myosin are arranged around dense bodies in the cytoplasm and are attached to attachment plaques in the plasma membrane rather than in sarcomeres.
name: Contain dense bodies and attachment plaques
label: a
answer: yes

Correct answer: a
Which of the following statements about vascular resistance is true?

Options:
explanation: Viscosity has more effect on the flow in vessels than density as most flow is laminar (except some turbulent at branch points). The role of viscosity in laminar flow resistance is described by Poiseuille's law: resistance is proportional to the length of the tube multiplied by the viscosity of the fluid divided by the 4th power of the radius of the tube. Density has more effect on resistance during turbulent blood flow.
name: In the majority of the lumens of blood vessels, the density of the blood has more effect than the viscosity
label: b
answer: no
explanation: In small vessels such as capillaries, erythrocytes tend to flow centrally and the plasma peripherally. This causes a cell-free plasma layer which effectively decreases the viscosity of the blood, decreasing resistance to flow. This is known as the Fahraeus-Lindqvist effect in which the effective viscosity of a fluid changes depending on the diameter of the tube it is flowing through.
name: In small vessels, erythrocytes tend towards the peripheries
label: d
answer: no
explanation: The majority of the total peripheral resistance of vessels is due to the arterioles, otherwise known as the resistance vessels. Indeed, the decrease in mean pressure from the large arteries to the capillaries is the largest change in any part of the vascular system. This is one of the reasons why altering tunica media contraction in arterioles is one of the main methods used to regulate the blood flow to a tissue.

<br>
name: The majority of total peripheral resistance comes from the capillaries
label: e
answer: no
explanation: This is true as the resistance of a liquid in a tube is inversely proportional to the 4th power of the radius of the tube. This is described by Poiseuille's law: resistance is proportional to the length of the tube multiplied by the viscosity of the fluid divided by the 4th power of the radius of the tube.
name: Dilating a vessel to double the diameter will reduce its resistance to 12.5% of the previous value
label: a
answer: yes
explanation: Longer tubes have higher resistances to fluid flow than shorter tubes. This is described by Poiseuille's law: resistance is proportional to the length of the tube multiplied by the viscosity of the fluid divided by the 4th power of the radius of the tube.
name: The longer the vessel, the lower the internal resistance
label: c
answer: no

Correct answer: a
According to Starling's law, an increase in pre-load in a non-failing heart will cause what?

Options:
explanation: In a non-failing heart, the increased contraction of the ventricle clears the increased end-diastolic volume. This prevents a significant increase in right atrial pressure. However, in a failing heart, contraction cannot increase sufficiently, thus increasing right atrial pressure as insufficient blood is cleared. This causes the release of atrial natriuretic peptide from the atrium and B-type natriuretic peptide (BNP) from the ventricles. BNP and NT-pro-BNP are therefore used as markers of heart failure.
name: A significant rise in right atrial pressure
label: c
answer: no
explanation: When pre-load is increased, the increased venous return causes the right atrium and ventricle to be more distended by the end of diastole. The contraction of the right ventricle is increased by this distension. Pulmonary venous return is increased by the same proportion, increasing the distension of the left ventricle. The same increase in contraction occurs, therefore increasing cardiac output to the same amount as the venous return.
name: Decreased cardiac output
label: b
answer: no
explanation: The Anrep effect describes how increased stretch on a cardiomyocyte causes increased calcium entry into the cytoplasm, increasing the contraction of the ventricles. This explains why increased end-diastolic volume during increased pre-load causes increased contraction and increases cardiac output in accordance with Starling's law.
name: Decreased calcium entry into cardiomyocytes
label: d
answer: no
explanation: When pre-load is increased, the increased venous return causes the right atrium and ventricle to be more distended by the end of diastole. The contraction of the right ventricle is increased by this distension. Pulmonary venous return is increased by the same proportion, increasing the distension of the left ventricle. The same increase in contraction occurs, therefore increasing cardiac output to the same amount as the venous return.
name: Increase in end-diastolic volume of the ventricles
label: a
answer: yes
explanation: Peripheral oedema would occur in a failing heart due to the inability of the heart to maintain a low right atrial pressure upon increased pre-load. This increases venous pressure and decreases re-absorption of fluid at the venous end of capillaries, resulting in peripheral oedema. Furthermore, the decreased ability to increase cardiac output in heart failure results in the renal retention of fluid, increasing pre-load further and worsening peripheral oedema.

<br>
name: Peripheral oedema
label: e
answer: no

Correct answer: a
An increase in capillary permeability will cause what changes according to Starling's equation?

JV = K((Pc - Pif) - 𝝈(𝝅c - 𝝅if))

Options:
explanation: Increased capillary permeability to proteins will increase protein extravasation, increasing the extracellular fluid colloid pressure and by extension, fluid extravasation. In Starling's equation, this decreases the value of 𝝈(𝝅c - 𝝅if), increasing the value of JV (JV represents the net extravasation of fluid by the end of the capillary bed).
name: Decreased fluid extravasation
label: d
answer: no
explanation: Increased capillary permeability to proteins will increase protein extravasation, increasing the extracellular fluid colloid pressure and by extension, fluid extravasation. In Starling's equation, this decreases the value of 𝝈(𝝅c - 𝝅if), increasing the value of JV (JV represents the net extravasation of fluid by the end of the capillary bed).
name: Increased fluid extravasation
label: a
answer: yes
explanation: Capillaries are incapable of active vasodilation or vasoconstriction as they consist of an endothelial layer without contractile tunica media.

<br>
name: Vasodilation
label: e
answer: no
explanation: Increased capillary permeability to proteins will increase protein extravasation, increasing the extracellular fluid colloid pressure and by extension, fluid extravasation. In Starling's equation, this decreases the value of 𝝈(𝝅c - 𝝅if), increasing the value of JV (JV represents the net extravasation of fluid by the end of the capillary bed).
name: Decreased protein in the extracellular fluid
label: b
answer: no
explanation: Capillary hydrostatic pressure can be increased by increasing cardiac output, decreasing arteriolar resistance proximal to the capillary, or increasing venous pressure distal to the capillary. Changes in the permeability of the capillary will not significantly affect any of these factors, therefore will not increase capillary hydrostatic pressure.
name: Increased capillary hydrostatic pressure
label: c
answer: no

Correct answer: a
A patient's FEV1/FVC is found to be 0.9.

Which of the following conditions do they most likely have?

Options:
explanation: An obstructive pattern is seen in asthma: FEV1/FVC is less than 0.75. This occurs because the inflammatory bronchoconstriction increases the resistance to airflow, especially during acute attacks in which a wheeze can be auscultated.
name: Asthma
label: c
answer: no
explanation: In pulmonary fibrosis, a restrictive pattern is seen in which FEV1/FVC is greater than 0.75. This occurs as the fibrotic lung cannot expand to the same degree as the normal lung but its airways remain open, allowing rapid flow on exhalation. Patients have a decreased capacity to inhale (decreasing forced vital capacity).
name: Pulmonary fibrosis
label: a
answer: yes
explanation: In healthy lungs, FEV1/FVC is usually 0.75-0.85. Any higher represents a restrictive pattern, whilst lower represents an obstructive pattern. In these conditions, both FEV1 and FVC are often reduced however, one is more decreased than the other, resulting in the characteristic ratios.

<br>
name: Healthy lungs
label: e
answer: no
explanation: In cystic fibrosis, an obstructive pattern is seen in which FEV1/FVC is less than 0.75. This occurs as defective CFTR decreases chloride secretion into the alveoli, decreasing osmosis into the bronchioles, and resulting in thick mucus which narrows and blocks the airways.
name: Cystic fibrosis
label: d
answer: no
explanation: An obstructive pattern is seen in COPD with emphysema: FEV1/FVC is less than 0.75. This occurs because the bronchioles narrow increasing resistance to flow while the parenchyma loses its elasticity which decreases the ability of the lung to expel air without increased effort. This results in the dichotomy of the 'red puffers' who can expend this increased effort, and the 'blue bloaters' who cannot.
name: COPD with emphysema
label: b
answer: no

Correct answer: a
A patient is infused with inulin at a constant rate until arterial concentration stabilises at 100uM. The infusion concentration of inulin is 250uM, and the patient is infused with 50ml of this solution per hour.

Assuming inulin is freely filtered and not reabsorbed, what is the patient's GFR?

Options:
explanation: At a steady arterial concentration, the rate infused is equal to the rate urinated out, and if a substance is freely filtered and not reabsorbed or actively excreted, its clearance is equal to the GFR.
Clearance x arterial concentration = urinary rate x urinary concentration = infusion rate x infusion concentration
GFR = (infusion rate x infusion concentration)/arterial concentration
GFR = (50ml/min x 250umol/L)/100umol/L
GFR = 50ml/min x ((250umol/L)/(100umol/L)) = 50ml/min x 2.5 = 125ml/min
name: 125ml/min
label: a
answer: yes
explanation: At a steady arterial concentration, the rate infused is equal to the rate urinated out, and if a substance is freely filtered and not reabsorbed or actively excreted, its clearance is equal to the GFR.
Clearance x arterial concentration = urinary rate x urinary concentration = infusion rate x infusion concentration
GFR = (infusion rate x infusion concentration)/arterial concentration
GFR = (50ml/min x 250umol/L)/100umol/L
GFR = 50ml/min x ((250umol/L)/(100umol/L)) = 50ml/min x 2.5 = 125ml/min
name: 120ml/min
label: b
answer: no
explanation: At a steady arterial concentration, the rate infused is equal to the rate urinated out, and if a substance is freely filtered and not reabsorbed or actively excreted, its clearance is equal to the GFR.
Clearance x arterial concentration = urinary rate x urinary concentration = infusion rate x infusion concentration
GFR = (infusion rate x infusion concentration)/arterial concentration
GFR = (50ml/min x 250umol/L)/100umol/L
GFR = 50ml/min x ((250umol/L)/(100umol/L)) = 50ml/min x 2.5 = 125ml/min

<br>
name: 25ml/min
label: e
answer: no
explanation: At a steady arterial concentration, the rate infused is equal to the rate urinated out, and if a substance is freely filtered and not reabsorbed or actively excreted, its clearance is equal to the GFR.
Clearance x arterial concentration = urinary rate x urinary concentration = infusion rate x infusion concentration
GFR = (infusion rate x infusion concentration)/arterial concentration
GFR = (50ml/min x 250umol/L)/100umol/L
GFR = 50ml/min x ((250umol/L)/(100umol/L)) = 50ml/min x 2.5 = 125ml/min
name: 20ml/min
label: d
answer: no
explanation: At a steady arterial concentration, the rate infused is equal to the rate urinated out, and if a substance is freely filtered and not reabsorbed or actively excreted, its clearance is equal to the GFR.
Clearance x arterial concentration = urinary rate x urinary concentration = infusion rate x infusion concentration
GFR = (infusion rate x infusion concentration)/arterial concentration
GFR = (50ml/min x 250umol/L)/100umol/L
GFR = 50ml/min x ((250umol/L)/(100umol/L)) = 50ml/min x 2.5 = 125ml/min
name: 100ml/min
label: c
answer: no

Correct answer: a
Glutamine is particularly important in the proximal convoluted tubule for which of the following reasons?

Options:
explanation: Glutamine is metabolised to glutamate then a-ketoglutarate, releasing ammonium at each step. A-ketoglutarate is then metabolised to malate, releasing bicarbonate. Malate is then metabolised through the Krebs cycle and gluconeogenesis into glucose, releasing more bicarbonate in the process. The bicarbonate released can be reabsorbed to alkalinise the blood while the ammonia and protons produced are excreted and trapped as ammonium in the lumen.
name: Used in bicarbonate synthesis
label: a
answer: yes
explanation: Potassium is reabsorbed in an unregulated manner in the proximal convoluted tubule by potassium-chloride co-transporters, in the thick ascending loop of Henle using NKCC2, and in the collecting ducts using potassium-proton exchanging ATPases. It is mainly in the distal convoluted tubule where potassium is excreted under the control of aldosterone through the action of the basal sodium-potassium exchanger ATPase and apical potassium channels. Glutamine does not have a significant role.
name: Used to secrete potassium
label: d
answer: no
explanation: Although glutamine is used in protein translation, this is a function common to all metabolically active cells and not notably more important in the proximal convoluted tubule.
name: Used to build proteins
label: b
answer: no
explanation: Sodium is reabsorbed in an unregulated manner under the power of the basolateral sodium-potassium exchanger ATPase in the thick ascending limb (using apical NKCC2). Sodium is also reabsorbed in an unregulated manner in the proximal convoluted tubule using apical SGLT-1/2, and in a regulated manner due to angiotensin 2 which increases the expression of apical sodium-proton exchangers. Sodium is also reabsorbed under the control of aldosterone through the induction of expression of ENaC on the apical membranes of distal convoluted tubule cells. Glutamine does not have a significant role.

<br>
name: Used to reabsorb sodium
label: e
answer: no
explanation: Fatty acids are the main source of energy in the proximal convoluted tubule. It is in the gastrointestinal epithelium where glutamine is metabolised extensively as an energy source as well as to provide ammonium for the synthesis of other amino acids.
name: Used as the main source of energy
label: c
answer: no

Correct answer: a
Which of the following describes the generation of ion gradients in the production of saliva by acinar cells?

Options:
explanation: This occurs in salivary duct cells, driven by the Na/K-ATPase. This process occurs to reduce sodium content in the saliva, allowing the glial-like cells of the taste buds to more sensitively detect dietary sodium.
name: Sodium is absorbed from the lumen by apical channels and sodium-proton exchangers and returned to the extracellular fluid
label: b
answer: no
explanation: Driven by sodium gradients (into the cell, maintained by the Na/K-ATPase), basolateral NKCC1 brings chloride (alongside sodium and potassium) into salivary acinar cells. This creates a chloride concentration gradient from the cell into the lumen which chloride diffuses down via apical channels. This generates an electrochemical and osmolality gradient which results in the para-cellular flux of sodium and water into the lumen, generating saliva.
name: Chloride is actively secreted using basolateral NKCC1 and apical channels, resulting in passive sodium flux into the lumen
label: a
answer: yes
explanation: This occurs in pancreatic ducts, alkalinising secretions. The bicarbonate is generated by carbonic anhydrase from CO2 and water, and the proton is reabsorbed into the extracellular fluid by a sodium-proton exchanger while the chloride diffuses back into the lumen via apical channels.
name: Bicarbonate is generated in acinar cells and secreted in exchange for chloride by chloride-bicarbonate exchangers
label: d
answer: no
explanation: This is part of the mechanism of gastric acid secretion by parietal cells. The bicarbonate is generated by carbonic anhydrase from CO2 and water, and the proton generated is secreted in exchange for potassium by a proton-potassium exchanger ATPase.
name: Chloride moves down its gradient from the extracellular fluid into cells using basolateral chloride-bicarbonate exchangers and diffuses into the lumen using apical channels
label: c
answer: no
explanation: This describes some of the ion flux in the large intestine in which sodium and chloride are absorbed to draw water out of the faeces. Potassium may be re-secreted under the control of aldosterone depending on the plasma concentration.

<br>
name: Sodium diffuses into cells from the lumen using ENaC and potassium exits (apical potassium channels) while chloride diffuses down a para-cellular concentration gradient
label: e
answer: no

Correct answer: a
Which factor secreted by enterochromaffin-like cells stimulates gastric acid secretion by parietal cells?

Options:
explanation: Histamine is secreted by enterochromaffin-like cells and binds H2 receptors. These receptors are Ga-s coupled GPCRs and stimulate adenylate cyclase, raising cAMP levels in parietal cells which, through activating the PKA phosphorylation of targets, leads to increased gastric acid secretion.
name: Histamine
label: a
answer: yes
explanation: Somatostatin is secreted by D-cells, binding Ga-i coupled somatostatin receptor GPCRs which inhibit adenylyl cyclase activity, reducing cAMP generation in parietal cells. This reduces PKA activation and by extension, its target phosphorylation which reduces gastric acid secretion.
name: Somatostatin
label: d
answer: no
explanation: Gastrin is secreted by G-cells and binds CCK-B receptors and Ga-q coupled GPCRs which activate PLC. PLC generates IP3 which binds to IP3 receptors, causing calcium efflux from endoplasmic reticular stores in parietal cells which activates other effectors and leads to increased gastric acid secretion.
name: Gastrin
label: b
answer: no
explanation: ACh is secreted by vagal efferents to the stomach and binds Ga-q coupled GPCR M3 muscarinic receptors which activate PLC. PLC generates IP3 which binds IP3 receptors, causing calcium efflux from endoplasmic reticular stores in parietal cells which activates other effectors and leads to increased gastric acid secretion.
name: Acetylcholine (ACh)
label: c
answer: no
explanation: Ghrelin is secreted by cells of the gastric fundus when the stomach has been empty for several hours. It acts in the arcuate nucleus of the hypothalamus to stimulate neuropeptide-Y-secreting neurons which act on Y1/Y5 receptors of the lateral hypothalamus which signal hunger to other relevant parts of the brain involved in motivation, emotion and decision making such as the basal ganglia, amygdala and pre-frontal cortex. Ghrelin also stimulates AgRP-releasing neurons which antagonise a-melanocyte stimulating hormone at melanocortin 3/4 receptors in the ventromedial hypothalamus to reduce the generation of satiety signals.

<br>
name: Ghrelin
label: e
answer: no

Correct answer: a
Which factor released by the anterior pituitary stimulates the secretion of a hormone which, when in excess, can cause weight gain, muscle wasting, insulin resistance and depressed immune responses?

Options:
explanation: Excess PRL in hyperprolactinaemia causes weight gain, amenorrhoea, infertility, galactorrhoea (inappropriate lactation), decreased libido, vaginal dryness, erectile dysfunction and loss of facial hair.

<br>
name: Prolactin (PRL)
label: e
answer: no
explanation: Excess ACTH causes secondary hyperadrenocorticism: a form of Cushing's syndrome characterised by weight gain with muscle wasting, weakness (giving a 'lemon on a stick' appearance), shoulder fat 'hump', round 'moon face', hirsutism, bruising, abdominal striae, slow healing, hypertension, insulin resistance and depressed immune responses.
name: Adrenocorticotropic hormone (ACTH)
label: a
answer: yes
explanation: Excess thyroid-stimulating hormone causes secondary hyperthyroidism. This can be associated with goitre, weight loss, amenorrhoea, muscle wasting, heat intolerance, tremor, palpitations, exophthalmos and increased immune responses.
name: Thyroid-stimulating hormone (TSH)
label: c
answer: no
explanation: ADH is secreted from the posterior pituitary. Excess ADH is produced in the syndrome of inappropriate ADH secretion (SIADH) which is often secondary to malignancy or head injury. Symptoms of excess ADH include fluid retention and severe hyponatraemia.
name: Anti-diuretic hormone (ADH)
label: d
answer: no
explanation: Excess growth hormone can cause gigantism in childhood and acromegaly in adults (once the epiphyseal plates are fused). The generalised effects of excess growth hormone include weight gain, muscle growth, some insulin resistance and complex interactions with immune responses (broadly stimulatory but GH deficiency is not associated with an immune deficiency in humans).
name: Growth hormone (GH)
label: b
answer: no

Correct answer: a