Page 80 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)
1) Insulin

Nature Storage

Small protein consists of two chains of amino acids  stored in granules ➔ until it
joined together by three s-s bridges. is released by exocytosis is
response to some specific
 Derived from a single-chain precursor [proinsulin],

synthesized in the rough endoplasmic reticulum. stimulus

Control of Insulin secretion

Factors  insulin secretion  insulin

1- concentration of glucose in the plasma: Sympathetic nervous
a.  glucose   insulin secretion, how? stimulation 
i. Glucose   Ca++ entry into beta cells  draw adrenaline  inhibits
granules to surface of the cell  insulin secretion. insulin secretion  

ii. Glucose  promoting synthesis of proinsulin. plasma glucose.
b.  glucose   insulin secretion

2- circulating amino acids & free fatty acids.
3- several GI hormones  gastrin, secretin & cholecystokinin
4- the parasympathetic nervous system.

NB

Secretion begins to increase within 10 minutes following the ingestion of food  reaches a
peak in 30 to 45 minutes.

Actions of insulin

 blood glucose level: by stimulating the uptake of glucose from the blood into the
liver, adipose tissue & muscle.
a. This glucose is first used as an energy source.

b. Then stored in the form of glycogen in the liver & muscle.
c. Excess glucose is stored as fat in adipose tissue.
♠ Insulin exerts its important actions on the following tissues:

Liver Adipose tissue Muscle

a.  glucose uptake a.  glucose uptake a.  glucose uptake
b.  glycogenesis b.  free fatty acid uptake  b.  glycogenesis

c.  lipogenesis  lipogenesis C.  amino acid uptake 
 protein synthesis

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