Usmle Step1 Physiology

Front 1

Outward current or flow of + ions out of the cell has whats effect on the cell's membrane

Back 1

IT HYPERPOLARIZES THE CELL'S MEMBRANE. (K+ LEAVES THE CELL)

Front 2

Inward current or the flow of + ions into the cell results in..?

Back 2

DEPOLARIZATION OF THE CELL'S MEMBRANE (LIKE WHEN NA+ ENTERS THE CELL)

Front 3

In hyperkalemia, the cell is depolarized due to the high concentration of K+ though not to threshhold so the Na+ channels remain closed causing muscle weakness..what's this phenomenon called?

Back 3

ACCOMODATION

Front 4

Which valvular event coincides with the T wave?

Back 4

aortic valve closure

Front 5

A pt with meningitis would hyper or hypo-ventilate..why?

Back 5

Hyperventilate because there's an increase in H+ ions hence a decrease in ph 2/2 to infection triggering hyperventilation

Front 6

A pt develops acidosis. What effect does this have in the H+ concentration of the CSF?

Back 6

None because H+ cannot cross the BBB..Any increase of H+ ions in CSF is extrinsic (infection)

Front 7

If a pt breathing room air is given 100% o2, what happens to ventilation?

Back 7

Nothing. Only decreases in O2 content trigger ventilatory responses

Front 8

A pt presents with prolonged inspirations and short expirations..DX and which CNS area is damaged?

Back 8

Apneustic breathing..Caudal pons

Front 9

If a pt donates a kidney, what happens to GFR?

Back 9

It's cut in half to 60 ml/min

Front 10

If a pt losses 50% of functioning nephrons what happens to GFR?

Back 10

It decreases only 25% because the rest of nephrons compensate by increasinf glomerular capillary pressure

Front 11

If a pt donates a kidney, what happens to GFR?

Back 11

It's cut in half to 60 ml/min

Front 12

If a pt losses 50% of functioning nephrons what happens to GFR?

Back 12

It decreases only 25% because the rest of nephrons compensate by increasinf glomerular capillary pressure

Front 13

At maximal ADH secretion, where's most of the free h2o reabsorbed in the nephron?

Back 13

In the PCT..Even though ADH acts on the collecting duct, 2/3 of the H2O was already reabsorbed in the PCT

Front 14

At maximum effect of ADH, at what point on the nephron there's a maximal osmolarity?

Back 14

At the tip of the loop of henle and in the collecting duct

Front 15

At which point in the nephron is the lowest osmolality?

Back 15

Early DCT because h2o leaving the loop of henle is hypotonic but there's further reabsorption of electrolytes so DCT has a lower osmolality than the end of ascending loop of henle

Front 16

What happens to urine osmolality in an uncontrolled diabetic?

Back 16

Decreases because glucose isnt reabsorbed in the PCT so it drags h20 through the nephron creating an unconcentrated urine..hence polyuria

Front 17

What happens to HCO3- in RTA 2 and provide two examples of conditions in which this happens?

Back 17

PCT is unable to reabsorbe HCO3- so it's lost in the urine and the plasma concentration decreases as well..this leads to acid urine and blood..exp: Fanconi's syndrome and effect of Carbonic Anhydrase Inhibitors

Front 18

If the pituitary stalk is severed, which pituitary hormone would increase?

Back 18

Prolactin..because it's constantly inhibited

Front 19

Which drug maintains Mean Arterial Pressure by increasing Cardiac Output and decreasing Total Peripheral Resistance?

Back 19

Dobutamine

Front 20

In a pt on chronic steroids tx, which areas become atrophied and which one stays intact?

Back 20

The z. fasciculata and reticularis atrophy and z. glomerulosa statys intact because it's under control of angiotensin 2 and K+

Front 21

Why do hypercalcemia and hypokalemia result in polyuria?

Back 21

They both inhibit ADH at the kidney tubules

Front 22

Short 4th digit, mental retardation, short stature..Dx?

Back 22

Pseudohypoparathyroidism (normal levels but tissues are resistant)

Front 23

A pt presents w/ + prostate ca and spine mets. which drug tx should be initiated?

Back 23

Flutamide (inhibits testosterone at prostate receptors)

Front 24

A pt w/ metastatic prostate ca to the spine is treated and he becomes paralized. Which tx was started?

Back 24

GnRH agonists (Leuprolide...) they cause an increase in FSH and LH as well as testosterone

Front 25

A woman presents with irregular menses. Which phase varies in lenght?

Back 25

Follicular phase

Front 26

A pregnant in her 3rd trimester has an elevated po glucose tolerance test. There's no hx of DM. What's the cause of this?

Back 26

Human Placental Lactogen can induce gestational DM

Front 27

What's the mechanism by which milk synthesis is blocked until birth?

Back 27

High levels from the placenta prevent milk synthesis..after birth estrogen levels decrease and milk is produced

Front 28

A woman nursing her newborn is sexually active but doesn't conceive. What's the mechanism?

Back 28

Nipple stimulation inhibits dopamine which increases prolactin which inhibit GnRH leading to low levels of FSH and LH

Front 29

Pt presents with acute pancreatitis. What's the underlying enzymatic mechanism?

Back 29

Premature activation of trypsinogen in the pancreas

Front 30

A pt develops diarrhea and hypokalemia. Where's the location where the diarrhea developed?

Back 30

Colon..the colon secretes potassium