Chat gpt : The endothelium

Question 1

Endothelium overview

Answer 1

Lines all blood and lymphatic vessels (1–6 × 10¹³ cells).

Once considered just a barrier, it’s now seen as a dynamic endocrine organ (~1 kg).

Most endothelial cells (ECs) are in capillaries.

Question 2

Development & Heterogeneity

Answer 2

Develop from mesoderm.

heterogeneity of endothelial cells differ across tissues to adapt to local environment, and these differences are driven by local cues and epigenetic modifications

Question 3

Functions of the endothelium

Answer 3

Barrier function
Blood flow regulation
Haemostasis
Leukocyte recruitment (mediates leukocyte adhesion / migration during inflammation)
Hormone Trafficking (facilitates delivery and uptake of hormones from / to the blood)

Question 4

Epithelium as a barrier

Answer 4

• Maintains tissue fluid balance
• Continuous (brain or skin), Fenestrated (kidney or intestine), Discontinuous (liver or bone marrow)
• Paracellular or transcellular (between cells via tight junctions or through cells bia transcytosis)

Question 5

Epithelium and blood flow regulation

Answer 5

Produce vasodilators and vasoconstrictors, eg. Nitrous oxide, (vasodilater, anti inflammatory, etc)

Question 6

Epithelium in haemostasis

Answer 6

Antithrombotic, producing Nitrous Oxide and promotes fibrinolysis which prevents blockages, but during an injury they become pro-thrombotic and express TF, vWf, etc

Question 7

Dysfunction

Answer 7

Caused by reduced nitrous oxide availability and vessel damage leading to vascular diseases due to pro-inflammatory, pro-thrombotic and vasoconstriction phenotype