Autonomic NS Flashcards
(38 cards)
What is the Autonomic Nervous System (ANS)?
It’s the part of the nervous system that controls involuntary bodily functions like breathing, heartbeat, and digestion.
Which types of muscles and glands does the ANS innervate?
Smooth muscle, cardiac muscle, and glands
Does the ANS operate consciously or subconsciously?
Subconsciously.
How many neurons are in an autonomic pathway?
Two neurons: a preganglionic and a postganglionic neuron
Where is the cell body of the preganglionic neuron located?
In the CNS.
Is the preganglionic neuron myelinated or unmyelinated?
Myelinated.
Where is the cell body of the postganglionic neuron located?
In the autonomic ganglion.
Is the postganglionic neuron myelinated or unmyelinated?
Unmyelinated.
Myelinated vs Unmyelinated Neurons
Myelin = Insulation Layer
Imagine an electric wire. It works better and faster when it’s covered in plastic insulation, right?
Similarly, myelin is a fatty coating around some neurons that helps electrical signals travel faster.
💡 Myelinated Neurons
Have myelin sheaths.
Faster transmission of nerve impulses.
Like a super-fast express train on a smooth track.
💡 Unmyelinated Neurons
Do not have this insulation.
Impulses travel slower.
Like a local train that stops more often.
🧪 In the ANS:
The preganglionic neuron is myelinated (fast signal from CNS to ganglion).
The postganglionic neuron is unmyelinated (slower signal from ganglion to organ).
What are the two main divisions of the ANS?
Sympathetic and Parasympathetic
What are visceral reflexes?
Reflexes that control involuntary functions in internal organs.
What’s a major difference between the somatic nervous system and the ANS?
Somatic controls voluntary movements, while ANS controls involuntary functions
What are the two types of cholinergic receptors?
Nicotinic and Muscarinic.
Where are nicotinic receptors found?
On motor end plates, all ganglionic neurons, and adrenal medulla cells.
Is the effect of ACh on nicotinic receptors excitatory or inhibitory?
Always excitatory
Where are muscarinic receptors found?
On all effector cells stimulated by postganglionic cholinergic fibers
Is the effect of ACh on muscarinic receptors always the same?
No, it can be excitatory or inhibitory depending on the organ.
What are the two types of adrenergic receptors?
Alpha (α) and Beta (β).
What is the general effect of NE on α receptors?
Stimulatory.
NE stands for norepinephrine (also called noradrenaline).
What is the general effect of NE on β receptors?
Inhibitory (except β receptors in the heart, which are stimulatory).
What is dynamic antagonism in ANS?
When sympathetic and parasympathetic systems oppose each other to maintain balance.
What does the sympathetic system do to heart and respiratory rate?
Increases them
What does the parasympathetic system do to heart and respiratory rate?
Decreases them.
What is the role of the parasympathetic system?
Rest and Digest – conserves energy and promotes digestion.
