ANS Adrenoceptors

Question 1

Describe the messenger proteins involved with Type Alpha 1 Adrenoceptors, what they do if activated and where they are found.

Answer 1

Proteins involved are IP3 and DAG.
When activated it causes vasoconstriction and are commonly found in VSM, urethra, and piloerector muscle (for thermoregulated skin hairs)

Question 2

Describe the Alpha 2 adrenoceptors. Name the proteins involved, what they do and where they are most likely found.

Answer 2

Alpha 2 uses the G(i) messenger protein to mediate negative feedback regulation when activated. They are found in post-ganglionic fibers influencing the controlled secretion of hormones such as insulin.

Question 3

Describe the following for the Beta 1 Adrenoceptor.

Protein involved, what happens when activated and where they are found.

Answer 3

Involves G(s) proteins. When stimulated, it can play a part in heart contractility, HR and blood pressure relating to the heart. These receptors are found in the SA node, ventricular myocytes, adipose tissue, and renal JG cells.

Question 4

Describe the Beta 2 Adrenoceptor. Talk about what they influence when activated, the messenger protein involved and where found.

Answer 4

These influence bronchiole relaxation (dilation) to enhance breathing rate, affect the VSM, the GI tract, and the liver (glycolysis and gluconeogenesis). The protein involved is the G(s) protein. These are found in ventricular myocytes, bronchial smooth muscle, the GI smooth muscle, ciliary muscle, skeletal muscle and VSM.

Question 5

Describe the Beta 3 Adrenoceptor. What protein is involved, what is the effect when activated and where are they found.

Answer 5

B3 works with the G(s) protein. When stimulated they work in the heart and in adipose tissue for the breakdown of lipids for energy (lipolysis).