receptors of ANS

Question 1

Nicotinic receptors

Answer 1

1) Nueronal (Nn): post-ganglionic neurons
2) Muscle (Nm): skeletal muscle (somatic NS!)

both types are pentameric, ACh-gated, non-selective cation channels - channel opening and depolarization

Question 2

muscarinic receptors

Answer 2

5 types (M1-M5) located on target cells all GPCRs that bind ACh

Question 3

M1, M3, M5

Answer 3

increase IP3 (calcium) and DAG smooth muscle contraction by M3 receptors neuroregulation by M1 receptors

**think M3 = IP3

Question 4

M2, M4

Answer 4

decrease cAMP, hyperpolarization slowing of HR and inhibition of NTM release by M2 (autoreceptor)

Inhibitory effect – need to hyperpolarize because you don’t want to stimulate the heart muscle

Question 5

adrenergic receptors

Answer 5

• GPCRs
• activated by NE or epi
• alpha1- vasoconstriction
• alpha2- inhibition of NTM release (autoregulation)
• Beta1- increase HR Beta2- smooth muscle relaxation (bronchioles)
• Beta3- lipolysis

Question 6

M3 receptors

Answer 6

pupillary constriction, bronchoconstriction and salivation

smooth muscle constriction via PLC –> PIP2 hydrolysis –> IP3 –> calcium release –> myosin light chain kinase activation

Question 7

M2 receptors

Answer 7

slowing of HR and acts as autoreceptor in presynaptic neuron (ie: in M2 KO mice, you get no change in HR and increased bronchoconstriction because there is no negative feedback of ACh release on M3 receptor)