physio - efferent division

Q: What are the two divisions of the efferent nervous system?

A:

1. Somatic nervous system (SNS) – Controls voluntary skeletal muscle movements.

2. Autonomic nervous system (ANS) – Controls involuntary functions like heart rate and digestion.

Q: What is the main function of the efferent division?

A: To send motor commands from the CNS to effectors (muscles and glands).

Q: What are the two branches of the autonomic nervous system (ANS)?

A:

1. Sympathetic division – “Fight or flight” response.

2. Parasympathetic division – “Rest and digest” response.

Q: How does the efferent division differ from the afferent division?

A:

• Efferent division: Sends motor signals from CNS to effectors.

• Afferent division: Sends sensory signals from receptors to CNS.

Q: How does the somatic nervous system (SNS) differ from the autonomic nervous system (ANS)?

Q: What type of neurotransmitter does the somatic nervous system use?

A: Acetylcholine (ACh), which always excites skeletal muscle.

Q: What is a key difference in neural pathways between the SNS and ANS?

A:

• SNS: A single motor neuron directly innervates skeletal muscle.

• ANS: Uses two neurons (preganglionic & postganglionic) to reach effectors.

Q: What are the general functions of the sympathetic nervous system (SNS)?

A: “Fight or flight” – Prepares the body for emergency responses:

• ↑ Heart rate & blood pressure

• Bronchodilation (airway expansion)

• Increased glucose release

• Reduced digestion & urination

Q: What are the general functions of the parasympathetic nervous system (PNS)?

A: “Rest and digest” – Promotes relaxation and energy conservation:

• ↓ Heart rate & blood pressure

• Bronchoconstriction (airway narrowing)

• Increased digestion & urination

• Energy storage

Q: Where do sympathetic preganglionic neurons originate?

A: In the thoracolumbar region (T1–L2 of the spinal cord).

Q: Where do parasympathetic preganglionic neurons originate?

A: In the brainstem and sacral spinal cord (craniosacral division).

Q: What are the two types of autonomic neurons in the ANS pathway?

A:

1. Preganglionic neurons – Originate in the CNS, release ACh, and synapse in autonomic ganglia.

2. Postganglionic neurons – Originate in ganglia, release either ACh or norepinephrine (NE) to target organs.

Q: What neurotransmitter is released by preganglionic neurons in both the sympathetic and parasympathetic systems?

A: Acetylcholine (ACh).

Q: What neurotransmitter is released by postganglionic neurons?

A:

• Sympathetic postganglionic neurons → Norepinephrine (NE).

• Parasympathetic postganglionic neurons → Acetylcholine (ACh).

Q: Where are autonomic ganglia located in the sympathetic vs. parasympathetic systems?

A:

• Sympathetic ganglia: Near the spinal cord.

• Parasympathetic ganglia: Near or inside the target organs.

Q: How is the adrenal medulla unique in the sympathetic nervous system?

A: Instead of a postganglionic neuron, it directly releases hormones (epinephrine & norepinephrine) into the bloodstream.

Q: What is the function of the adrenal medulla in stress responses?

A:

• Releases 80% epinephrine & 20% norepinephrine into circulation.

• Amplifies the fight-or-flight response.

• Prolongs sympathetic effects beyond synaptic transmission.

Q: What are the two main types of cholinergic receptors?

A:

1. Nicotinic (nAChR) – Found in autonomic ganglia & neuromuscular junctions (ionotropic, fast).

2. Muscarinic (mAChR) – Found in parasympathetic target organs (metabotropic, slower).

Q: What are the three types of adrenergic receptors, and their effects?

A:

1. α1 receptors → Vasoconstriction (increased blood pressure).

2. β1 receptors → ↑ Heart rate & contractility.

3. β2 receptors → Bronchodilation & skeletal muscle vasodilation.

Q: Which receptor is responsible for bronchodilation?

A: β2 adrenergic receptor.

Q: Which receptor increases heart rate and contractility?

A: β1 adrenergic receptor.

Q: Which receptor causes pupil constriction?

A: Muscarinic (mAChR) receptor.

Q: Which receptor causes vasoconstriction in the skin & mucosa?

A: α1 adrenergic receptor.

Q: Which receptor is found at the neuromuscular junction (NMJ)?

A: Nicotinic (nAChR) receptor.

Q: What type of drugs block sympathetic activity?

A: Beta-blockers (e.g., propranolol) – Block β1 receptors, reducing heart rate & blood pressure.

Q: What type of drugs enhance parasympathetic activity?

A: Cholinergic agonists (e.g., pilocarpine) – Activate muscarinic receptors to increase digestion & urination.

Q: What type of drugs increase sympathetic effects?

A: Adrenergic agonists (e.g., albuterol) – Activate β2 receptors for bronchodilation.