The transition from the closed to the open complex involves structural changes in the enzyme and the opening of the DNA double helix to reveal the template and nontemplate strands. This “melting” occurs between positions –11 and +2, with respect to the transcription start site.

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#Id: 6525

#Unit 7. System Physiology – Animal

Norepinephrine produces vasoconstriction via  α1 receptors, but epinephrine dilates the blood vessels in skeletal muscle and liver via β2 receptors

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#Id: 6526

#Unit 7. System Physiology – Animal

Catecholamines increase the secretion of insulin and glucagon via β-adrenergic mechanisms and inhibit the secretion of these hormones via α-adrenergic mechanisms

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#Id: 6527

#Unit 7. System Physiology – Animal

The pancreas is composed of two major types of tissues, as: 

the acini

the islets of Langerhans

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#Id: 6528

#Unit 7. System Physiology – Animal

Insulin, 

synthesized and secreted 

by the β cells

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#Id: 6529

#Unit 7. System Physiology – Animal

Insulin has an AB heterodimer structure with 

One intrachain (A6-A11) 

Two interchain disulfide bridges (A7-B7 and A20-B19)

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#Id: 6530

#Unit 7. System Physiology – Animal