Phisiology Flashcards
Why low estrogen state (postmenopausal, ovary dysfunction or surgical remove) favors development of osteoporosis?
⬇️ Estrogen ▶️ ⬇️ Osteoprotegerin ⬆️ RANK-L ▶️ (+) differentiation to active osteoclasts ▶️ bone resorption
⬇️ Estrogen ▶️ ⬆️ RANK in osteoclasts precursors
Pulmonary function test pattern in pulmonary fibrosis.
- Restrictive pattern: ⬇️ lung volumes
⬇️ FEV1, FVC
Normal or ⬆️ FEV1/FVC ratio
⬇️ Diffusion capacity (DLCO)
Excess copper (from senescence ceruloplasmin and not absorbed) is mainly excreted by which pathway?
Secreted into bile ▶️ excreted in stools
-Renal tubular secretion ▶️ 5-15% of excretion
Which component of surfactant rises in amniotic fluid at week 36 and which at week 30?
- Phosphatidylglycerol ▶️ 36 week
- Phosphatidylcholine (lecithin) ▶️ 30 week
Where is controlled the respiratory rate? How is it regulated based on oxygen content?
Medullary respiratory center based on input from:
- central chemoreceptors (medulla) ▶️ PaCO2 (mainly in healthy)
- peripheral chemoreceptors (carotid and aortic bodies) ▶️ PaO2 (mainly in severe hypoxia)
In a water deprivation state (ex, dehydration) which portion of the nephron has the most concentrated and the most diluted urine? why?
- Water deprivation state = ↑ADH levels →↑aquaporin-2 in principal cells at Collector ducts (V2R)→↑H2O reabsorption→most concentrated urine
- Ascending loop of Henle→↑NaCl reabsorption→dilution
- Distal convoluted tubule most diluted urine (even more reabsorption of electrolytes, impermeable to water - lowest osmolarity [hypotonic] - regardless ADH levels)
What is the Jervel and Lange-Nielsen syndrome? why does it occur?
- Sensorineural hearing loss and congenital QT long syndrome
- Mutations (autosomal recessive) - KCNQ1, KCNE1 genes (voltage-gated K+ channels)→↓ K+ current→↑ action potential and QT duration.
Cause and ECG changes of Brugada syndrome.
- Mutations in cardiac sodium or L-type clacium channels
- pseudo right bundle branch block. ST-segment elevation V1-V3
*↑Risk ventricular tachyarrhythmias and sudden death
Which volumes are elevated in COPD patient, mainly in emphysema?
- Residual volume
- Functional Residual Capacity
- Total Lung Capacity
Differences between myoglobin and hemoglobin respect O2-Hb dissociation curve and affinity.
- Myoglobin ▶️ ⬆️ affinity O2 ▶️ hyperbolic curve (P50=1 mmHg)
- Hb ▶️ less afinity than myoglobin (Affinity ⬆️ after binding of 1 O2 molecule heme-heme interaction) ▶️ sigmoid curve (P50=26mmHg)
*myoglobin is equivalent to a 1 subunit (alpha or beta) of the Hb
What is the mechanism by which CO poisoning causes headache, dizziness, seizures, respiratory arrest?
Competitive binding to Hb and with 200x greater affinity than O2
Why stimulation of B1 adrenergic receptor (mainly ⬆️ the heart rate) affect systolic blood pressure? what is the effect?
➕B1 ▶️ ⬆️ HR and contractility ⏩ BP=CO(cardiac output)xHR ▶️ ⬆️ BP (mainly systolic)
Which protein allows the transport of neurotransmitter-containing secretory vesicles in the neurons?
Kinesin ▶️ microtubule-associated, ATP-powered motor protein ▶️ anterograde transport down axons to synaptic terminals
Why is less the ventilation at the apex of the lungs?
Gravity stretch downward the lungs from the apex - apex is fixed in pleural cavity by low intrapleural pressure (“pleural suction”) ▶️ Alveoli more stretched and expanded at apex than base during end-expiration ▶️ less air during inspiration (less compliance)
Why if ventilation and perfusion increases from apex to the base, the V/Q (ventilation/perfusion) ratio is greater in apex than base?
Perfusion (Q) ⬆️⬆️ > Ventilation (V) ⬆️
*“denominator is much greater and numerator is slighty increased in base”
Which are the changes on GFR, FF and RPF if selectively constrict efferent arteriole and afferent arteriole?
- Efferent arteriole constriction ▶️ ⬇️ glomerular blood outflow ▶️ ⬆️ glomerular capillary hydrostatic pressure ▶️ ⬆️ GFR; ⬇️ RPF (stasis) ⏩ FF=GFR⬆️/⬇️RPF=⬆️FF;
- If Efferent arteriole constriction continues ⬆️⬆️ ▶️ ⬆️ oncotic pressure more than hydrostatic in glomerulus ⏩ ⬇️ GFR
- Afferent arteriole constriction ▶️ ⬇️ plasma flow into glomerular capillaries ▶️ ⬇️ capillary hydrostatic pressure ▶️ ⬇️ GFR; ⬇️ RPF equal than GFR ⏩ FF unchanged
What happen when muscle make too much force, and what mediates that response?
Golgi tendous organ (GTO)▶️ interneuron ▶️ 🚫 alpha-motoneuron in spinal cord ⏩ sudden muscle relaxation
*GTO response to actively contraction of muscle to maintain muscle tension
Which regions of the sarcomere have only thick and only thin filaments? Which bands remain unchanged and which changes in length during contraction?
- Thick filaments (myosin) ▶️ band H
- Thin filaments (actin) ▶️ band I
- During contraction ▶️ band A not change, band I, H get shorter
Why during panic attack a patient can have drowsiness, dizziness, blurred vision, weakness (neurologic symptoms)?
Panic attack ▶️ hyperventilation ▶️ ⬇️ PaCO2 ▶️ hypocapnia ▶️ brain blodd vessel constriction (⬆️resistance) ▶️ ⬇️ cerebral blood flow
*CO2 ▶️ potent cerebral vasodilator (most powerful effect of the arterial blood gases on brain blood flow). PaO2<50mmHg (severe hypoxia) ▶️ vasodilation in brain vessels ▶️ ⬆️ cerebral blood flow and intracranial pressure
Which vitamins are lack in the newborn and must be supplemented and why?
- Vitamin K ▶️ immediately parenteral at delivery ▶️ prevent hemorrhagic disease of the newborn
- Vitamin D in exclusively breastfed, lack sunlight exposure, dark skin pigmentation ▶️prevent rickets
*Iron in preterm/low birthweight, breastfed >4 mo until initiate solid food
Which substances in excess can increase the resistance to insulin during pregnancy?
- Plancental growth hormone (PGH)→Placental maturation
- human Placental lactogen (hPL)→Fetal development
- TNF-α, leptin, adiponectin
What part of cardiac cycle is the sarcomere length of the left ventricular muscle fibers the greatest and the lowest?
- End diastolic volume→longest sarcomere length
- End systolic volume→shortest sarcomere length
When occur an intrapulmonary shunt?
When there is an area adequately perfused but poorly ventilated
What substances predominantly drive the angiogenesis?
- Vascular endothelial growth factor (VEGF)
- Fibroblast growth factor (FGF)
What is the approximate intrapleural pressure value at the functional residual capacity (FRC) point? Why?
- -5 mmHg
- Tendencies of chest wall to expand and lung to collapse oppose one another
- FRC point ▶️ positive alveolar transmural pressure and negative chest wall transmural pressure oppose one another equally ▶️ airway pressure of zero (different of intrapleural pressure) ▶️ no tendency of air to flow into or out the lungs ⏩ center of the airway pressure-volume curve
Where is the first site of electric activation of the heart?
Sinoatrial node (dominant pacemaker) ▶️ junction of the right atrium and superior vena cava
Which study can you order in a patient that suspect pulmonary embolism but has a contraindication to use contrast? What would be the result?
- Contrast contraindication ▶️ can not make CT angiography
- Ventilation/perfusion scan (V/Q) ▶️ area of perfusion defect without ventilation defect (mismatched perfusion defect) ⏩ V/Q mismatch
What wave of the jugular venous tracing is absent in atrial fibrilation? why? and when this wave can be prominent?
- a wave→atrial contraction
- A fib→no atrial contraction, no p wave on ECG, it is “fibrilating”
- Hypertrophic cardiomyopathy
Transient holosystolic murmur in a patient with congestive heart failure, dissapear with treatment.
Functional mitral regurgitation
- ↑Preload→Acute dilatation of LV→separate normal mitral valve leaflets
- Tx→↓preload and afterload
Why mature RBC can not synthesize Heme, even though they have cytoplasmic enzymes involved in Heme synthesis?
- Normally lack of Mitochondria→need to first and final 3 steps of Heme synthesis→no Heme→no Hb.
- Heme synthesis (every organ, but mainly)→RBC precursors in BM, hepatocytes (microsomal cytochrome P450)
*Mature RBCs don’t synthesize Hb, survive for 120 days
Functions of von Willebrand factor (vWF).
- Endothelial damage→vWF binds glycoprotein Ib receptors (GpIb) on platelet→platelet aggregation and adhesion to subendothelial collagen
- Carrier for factor VIII→prolongs its half-life
Effect of the vasopressin on urea clearance.
- Vasopressin→(+)V2 receptors in collecting ducts→↑permeability of urea in medullary collecting ducts→↓urea clearance
- Passive reabsorption of urea into medullary interstitium→↑medullary osmotic gradient→maximally concentrated urine