Differential action of cortisol on tissues- the cellular checkpoints at the tissue level

 

·       Cortisol (and some amount of cortisone) is produced by the adrenal cortex in response to stress

·       Like all hormones, cortisol is secreted directly into the circulation and distributed uniformly throughout the body.

·       Most tissues of the body (mainly the liver and the adipose tissues) are rich in glucocorticoid receptors and poor in mineralocorticoid receptors. They have the enzyme HSD-11β Type 1 which converts cortisone into cortisol and promotes glucocorticoid action.

·       Some tissues of the body (kidneys, liver, lungs, colon, salivary glands) are rich in mineralocorticoid receptors and poor in glucocorticoid receptors. They are very sensitive to mineralocorticoid action of cortisol. They have the enzyme HSD-11β Type 2 which converts active cortisol into inactive cortisone and prevent excessive mineralocorticoid action of cortisol.

Oxygen delivery devices

 

Mode of O2 delivery	Maximum flow rate (litres/min	FiO2	Other notable features
Nasal cannula / prongs	5	·       1 litre/min flow rate-24%, ·       increases by 4% with every litre increase in flow rate ·       6 litres/min flow rate-44%,	·       Narrow-bored flexible tubes. ·       One end of the tube is attached to a graduated oxygen flow meter, the other end is split into two nozzles that loosely fits into the nostrils. ·       Beyond flow rates of 5 litres/min, the flow becomes turbulent leading to dissipation of delivered oxygen at the entry portal.
Face mask (simple)	5-10	35-55%	·       It is an expanded semi-rigid hollow enclosure that fits over the nose and oral orifice. ·       Flow rates less than 5 litres/min are not recommended because there is rebreathing of trapped expired air
Venturi mask	(blue-2, white-4, orange-6, yellow-8, red-10 and green-15)	24, 28, 31, 35, 40 and 60 % respectively	·       Oxygen inlet to the face mask is fitted with oxygen content regulators of varying capacity. ·       The FiO2 can therefore be tightly controlled as per need of the patient
NRBM	10-15	Up to 100%	·       The oxygen inlet to the mask is side-fitted with an inflatable oxygen reservoir bag. ·       During inspiration, oxygen is sourced from the inflowing oxygen as well as from the reservoir.
(HFNC)	Maximum rate- 70 litres/min	Up to 100%	·       electromechanical device that generates an admixture of warm humidified air containing oxygen of desired concentration

The electrophysiology of cardiac action potential in non-pacemaker cells: watch the video

 The “heart” of the functioning of the heart is the fast cell to cell communication between the cardiac myocytes. Upon generation of the pacemaker potential, the impulse is transmitted electrically to the adjacent cells. An action potential begins with rapid firing of fast Na+ channels resulting in rapid depolarisation (phase 0), following which there is an early repolarisation (phase 1). In the phase 2, Ca++ moves into the cells triggering massive release of calcium from the endoplasmic reticulum. And the cell contracts...

Delve into the depths of the molecular mechanism of the cardiac action potential. Click the 

https://youtu.be/tHttyFRjddM

Ranolizine in ischemic heart disease

 https://youtu.be/-ZoM9dIfqSE

The mid life crisis in the life of a women. What can we do to help her?

A 45 year old lady presents with the chief complaint of irregular menses. She had amenorrohoea for the last three months but 10 days back the periods started with heavy menstrual bleeding and was still continuing. She had one living child aged 20 years. An abdominal ultrasound revealed no obvious abnormality that could explain the heavy menstrual bleeding. Her thyroid status was euthyroid. She has no history of any comorbid condition. What is the most likely diagnosis?    What treatment would you suggest for the patient?

Mechanism of action of sucralfate

 https://youtu.be/-uMkwAfSb-I

Loop diuretics increase calcium excretion and thiazides diuretics decrease calcium excretion

FUNCTION OF Na+ K+ 2Cl- channel

👉  Na K 2Cl channel at the thick ascending limb of loop of Henle is responsible for transport of  Na+, K+ and 2Cl- from intra-luminal to intra-cellular part of the loop of Henle.

👉K+ diffuses back into the lumen and Na+ is transported across the basolateral membrane to the ecf.

👉 Back diffusion of K+ into lumen creates a positive potential difference between the luminal (positive side) and basolateral (negativeside) membranes. 

👉 Positive potential difference drives reabsorption of Ca2+ and Mg2+  into the tubular capillaries.

MECHANISM OF INCREASED Ca+ EXCRETION BY LOOP DIURETICS

👉 Loop diuretics inhibit Na K 2Cl channel at the thick ascending limb of loop of henle.

👉  Reabsorption of Na K 2Cl does not occur

👉No development of positive potential difference.

👉No reabsorption of Ca2+

👉Increased excretion of Ca+

FUNCTION OF Na Cl SYMPORTER AT DISTAL TUBULE

👉 Reabsorption of only Na Cl. Therefore, unlike loop of Henle, there is no role of K+ back diffusion and therefore no question of positive potential difference.

👉 No potential difference driven Ca2+ reabsorption 

MECHANISM OF DECREASED Ca2+ EXCRETION BY THIAZIDE DIURETICS

👉  Inhibition of Na Cl symporter

👉 Decreased Na in tubular epithelial cells

👉 Compensatory increased functioning of Na+ Ca2+ exchanger at the basolateral membrane  to maintain  intracellular Na+.

👉 Decreased intracellular Ca in the epithelial cells.

👉 Increased reabsorption of Ca+ from luminal to intracellular side

👉Decreased Ca+ excretion in urine