UNIT 2 ANS ✨ Flashcards
What are the 4 classifications of receptors?
Ion channel, GPCR, Enzyme-linked receptor, Intracellular receptor
What is signal transduction?
The process by which a cell converts an extracellular signal into an intracellular response.
Describe the general architecture of the G protein second messenger system.
1st msgr = extracellular signal
Receptor = responds to extracellular signal
G protein = turn on or off an effector
Effector = activates or inhibits the 2nd msgr
2nd msgr = primary intracellular signal
Cellular response = causes a physiological change
What second messenger system is associated with the alpha-1 receptor?
Gq > PLC > IP3, DAG, Ca++
What other receptors share a similar pathway with the alpha-1 receptor?
Histamine-2, Muscarinic-1
What second messenger system is associated with the alpha-2 receptor?
Gi > AC > ATP 🡪 cAMP
What other receptors share a similar pathway with the alpha-2 receptor?
Muscarinic-2, Dopamine-2 (presynaptic)
What second messenger system is associated with the beta-1 and beta-2 receptors?
Gs > AC > ATP 🡪 cAMP
What other receptors share a similar pathway with beta-1 and beta-2 receptors?
Histamine-2, Vasopressin-2 (renal), Dopamine-1 (postsynaptic)
Describe the autonomic innervation of the heart.
SNS: cardiac accelerator fibers arise from T1-4
PNS: Vagus nerve (CN X)
Describe the autonomic innervation of the bronchial tree.
Beta-2 receptors are NOT innervated! They respond to catecholamines either in the systemic circulation or in airway (inhaled).
What is the primary neurotransmitter of the SNS?
Norepinephrine (NE)
What are the 3 ways that NE can be removed from the synaptic cleft?
- Reuptake – into presynaptic neuron (accounts for 80%)
- Diffusion – away from synaptic cleft
- Reuptake – by extraneural tissue
What enzymes metabolize NE and epi?
- MAO – monoamine oxidase
- COMT – catechol-O-methyltransferase
What is the final metabolic byproduct of NE and epi?
VMA (vanillylmandelic acid) or 3-methoxy-4-hydroxymandelic acid
List the 3 types of cholinergic receptors.
- Nicotinic-M (muscle)
- Nicotinic-N (nerve)
- Muscarinic
Where are Nicotinic-M receptors found?
Neuromuscular junction (NMJ)
Where are Nicotinic-N receptors found?
- Preganglionic fibers at autonomic ganglia (SNS & PSNS)
- CNS
Where are Muscarinic receptors found?
Postganglionic PNS fibers at effector organs and CNS
What are the 5 components of the autonomic reflex arc?
Compare and contrast the architecture of the SNS & PSNS efferent pathways.
Both have pre- and post-ganglionic nerve fibers.
PSNS: Long, myelinated, B-fiber (Ach); Short, unmyelinated, C-fiber (Ach).
SNS: Short, myelinated, B-fiber (Ach); Long, unmyelinated, C-fiber (NE).
What is the origin of the efferent SNS pathways?
Thoracolumbar: T1-L3; cell bodies arise from the intermediolateral region of the SC.
What is the origin of the efferent PNS pathway?
CranioSacral: CN 3, 7, 9, 10 and S2-4.
Describe the innervation of the adrenal medulla.
No POST-ganglionic fibers; it is in direct communication with the bloodstream.
