Page 160 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)
✓ Protein molecules are too large to pass freely through clefts.
In the brain The clefts are tight (blood brain barrier = BBB) ➔ Water soluble substance
pass by active transport
In the liver & intestine [GIT] The clefts are very wide (leaky)  allow passage of protein ➔ they need
rapid absorption

3- Large water-soluble * Can cross by pinocytosis.
substances

4- Venules

❖ formed from merged capillaries.
❖ two layers ➔(endothelium, connective tissue)

5- Veins (capacitance vessels)

❖ Carry non oxygenated blood from the tissue back to the heart  except pulmonary veins.
❖ Thin walled (have a thin tunica media layer) ➔ as it away from heart.
Characters
o Are under low pressure ➔ pressure decreased as away from heart.
✓ The volume of blood contained in the veins is called  the unstressed volume.

Act as blood reservoir (capacitance vessels)  as they hold 60-70% of blood volume in the cardiovascular system.
Functions
Have α1-Adrenergic receptors  sympathetic stimulation  Venoconstriction  unstressed volume &  venous return.
✓ Some vein contain Valves ➔ especially those in lower limb (chest, …)
✓ Have one-way valves (Bicuspid type) to  prevent flow back of blood. هعوجر عنتم

 During long standing the valve is damaged ( blood flow back since the valves do not close & this is called  varicose veins .
درولأا لىاود
Valves
هيقلايه عجري مدلا ىجي امل و لفقيه مامصلا ىلع طغضي و فلخلل عجرت اهنا لصحي أدبي و )سيوك شلفقتم( سيوك شلغتشتمف هبعتي و مامصلا ىلع طغضيب مدلا

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