Autonomic Physiology Flashcards
Where do parasympathetic fibers exit the CNS?
Cranial and Sacral
Where do sympathetic fibers exit the CNS?
Thoracic and Lumbar
What is the location of ganglia for Sympathetic and Parasympathetic fibers, respectively?
Sympathetic Chain (sympathetic)
On/near the target organ (parasympathetic)
Parasympathetic presynaptic axons are (LONG/SHORT) and the postsynaptic axons are (LONG/SHORT).
Long (must travel to ganglion on target organ)
Short
Sympathetic presynaptic axons are (LONG/SHORT) and the postsynaptic axons are (LONG/SHORT).
Short (must travel to sympathetic chain, just outside spine)
Long
Explain a reflex arc involving skeletal muscle.
Sensory (afferent) information is received, especially from pain fibers (i.e., burning your hand). The sensory information is then relayed to the CNS, in this case the Spinal Cord. The sensory fibers will synapse at a NMJ with the motor neuron that innervates the skeletal muscles (in this case, the hand) to move that particular body part.
In an autonomic reflex arc, the afferent (sensory) neuron and its information can be the same as things that elicit other reflexes. However, instead of relaying its information to the Spinal Cord, it is sent to…
Brain – particularly the Hypothalamus
What type of neuron will relay the signal to skeletal muscle?
Alpha Motor Neuron
For autonomic reflexes, this takes the place of the Alpha Motor Neuron.
Autonomic Nervous System
In the somatic motor system, there is ______ neuron(s) between the CNS and the target organ. In the autonomic nervous system, there is ______ neuron(s) between the CNS and the target organ.
One
Two
In the ANS, the pre-synaptic neuron (cell body in the CNS) will terminate in a _________ in the periphery. From here, the post-synaptic neuron will go to the target organ.
Ganglion
In the ANS, where do the cell bodies of the pre-synaptic and post-synaptic neurons lie?
Pre-synaptic – Cell body in CNS
Post-synaptic – Cell body in ganglion
In the ANS, how many synapses are there between the CNS and the target organ?
Two synapses –
1) In the ganglion
2) At the target organ
T/F. In the ANS, the synapse in the ganglion varies greatly between the sympathetic and parasympathetic systems.
False. The synapse is essentially the same between sympathetic and parasympathetic systems. Both use ACh and nAChR.
The pre-ganglionic axon (from CNS) releases __________ at its synapse between the pre- and post-ganglionic neurons (in the ganglia).
Acetylcholine (ACh)
In the ganglia, the post-ganglionic cell expresses what kind of receptor at its post-synaptic membrane?
Nicotinic Cholinergic Receptors (nAChR)
T/F. The second synapse, at the end organ, is different in the sympathetic and parasympathetic systems.
True
Explain the histology of the pre-synaptic component of the second synapse in the ANS.
Varicosities contain all the components of the pre-synaptic terminal (vesicles of neurotransmitters, mitochondria, etc.) and work exactly the same way as the pre-synaptic terminal of the NMJ.
Explain the histology of the post-synaptic component of the second synapse in the ANS.
The post-synaptic side has ligand-gated receptors that are not concentrated opposite the pre-synaptic terminal like in the NMJ. Instead, they are more spread out all over for the neurotransmitter to diffuse.
- **NMJ – mail in mailbox (SPECIFIC)
- **Varicosities – mail thrown in yard (NOT SPECIFIC)
What is the neurotransmitter released from the post-ganglionic axon (from ganglionic synapse) to the target organ?
ACh
The ACh from the post-synaptic axon binds to what kind of receptors on the target organ?
Muscarinic Cholinergic Receptors (mAChR)
***Parasympathetic ONLY
For mAChR receptors, _______ that is within the body binds to and activates them. The exogenous (not found in the body) chemical ________ can bind to these receptors and activate them as well.
ACh
Muscarine
T/F. Nicotine and Muscarine can activate both nAChR and mAChR.
False. Nicotine can only activate nAChR, and Muscarine can only activate mAChR. Acetylcholine can activate both.
Muscarinic receptors are part of the __________ (Serpentine) Super-Family of receptors. This means they are second messenger systems (aka GPCR). There are 5 subtypes.
Metabotropic
This subtype of muscarinic receptor can be found in the following locations:
- Found in CNS (not autonomic, role in memory)
- Salivary glands - increase secretion
- Acid secreting cells of stomach - increase secretion
M1R
This subtype of muscarinic receptor can be found in the following locations:
- Smooth muscle cells (contraction)
- Exocrine glands (secretion)
M3R
M1R and M3R are what type of GPCRs? What is the function of this type of GPCR?
Gq/11 – Increased intracellular Calcium (causes contraction)
This subtype of muscarinic receptor can be found in the following locations:
– Cardiac - Slow heart rate (on SA node)
M2R
M2R are what type of GPCRs? What is the function of this type of GPCR?
Gi/o – Decreased cAMP (also directly interacts at K+ channels)
What effect must M2R have on K+ channels in order to slow the heart rate?
Causes K+ to go out of the cell, which results in repolarization or hyperpolarization. This slows the heart rate.
In the second synapse of sympathetic fibers, the neurotransmitter released from the post-ganglionic axon is…
Norepinephrine
***Remember, parasympathetic is ACh!
In the second synapse, the norepinephrine released from the sympathetic post-ganglionic axon binds to what kind of receptor?
Adrenergic receptor
Like the muscarinic receptors, adrenergic receptors are members of the Serpentine Superfamily of receptors. They are connected to a second-messenger system that are activated when norepinephrine or epinephrine bind to them. The two major classes of adrenergic receptors are…
Alpha-Adrenergic receptors
Beta-Adrenergic receptors
This type of adrenergic receptor is a Gq/11 coupled receptor and can lead to increased Calcium intracellularly. It can cause vascular smooth muscle contraction, which will increase blood pressure.
Alpha-1 receptors
What type of adrenergic receptor is located in the following places:
- Smooth muscle of blood vessels (contraction)
- Smooth muscle of urinary and reproductive tracts
- Liver (glycogenolysis; gluconeogenesis) – Energy
- Adipose tissue (Lipolysis) – Energy
- Lacrimal glands (reduced watery secretion)
- Radial muscle of iris (contraction of muscle dilates pupil)
Alpha-1 receptors
This type of adrenergic receptor is a Gi/o coupled receptor and can lead to decreased adenylate cyclase/cAMP.
Alpha-2 receptors
What type of adrenergic receptor is located in the following places:
- GI sphincters (contraction)
- Pancreas (increased glucagon; decreased insulin)
- Smooth muscle of blood vessels (dilation)
- Platelets (increase clotting)
Alpha-2 receptors
This type of adrenergic receptor is a Gs coupled receptor and can lead to increased adenylate cyclase activity and cAMP production.
Beta1-adrenergic receptors
Beta2-adrenergic receptors
Beta3-adrenergic receptors
What type of adrenergic receptor is located in the following places:
- Cardiac tissue: SA node - Increased heart rate; Ventricular muscle - Increased strength of contraction
- Salivary glands - viscous secretion (Dry-mouth when speaking)
- Adipose tissue (Lipolysis) - Energy
Beta1-adrenergic receptors
What type of adrenergic receptor is located in the following places:
- Bronchiole smooth muscle (relaxation)
- GI smooth muscle (relaxation)
- Urinary/Reproductive smooth muscle (relaxation)
- Vascular smooth muscle (relaxation)
- Liver (glycogenolysis)
- Eye (relaxation of ciliary muscle - flattens lens)
Beta2-adrenergic receptors
This is an agonist of Beta2-adrenergic receptors that helps to stop an asthma attack.
Albuterol
What type of adrenergic receptor is located in the following places:
- White adipose tissue (lipolysis) - Energy
- Brown adipose tissue (heat production) - Thermogenesis
Beta3-adrenergic receptors
The Adrenal Medulla contains _________ cells that make and release epinephrine (adrenaline) as part of the sympathetic response.
Chromaffin
Instead of synapsing in the paravertebral ganglion, some sympathetic axons go through the ganglion and synapse in the…
Adrenal Medulla
In the sympathetic system and adrenal medulla, the pre-ganglionic axon releases ACh, which binds to nicotinic receptors on the…
Chromaffin cells
***Remember, the pre-ganglionic axon does NOT synapse in the paravertebral ganglion, it just passes through and goes straight to the Chromaffin cells in the Adrenal Medulla.
In the sympathetic system and adrenal medulla, the activation of the nicotinic receptors on the Chromaffin cells leads to the release of…
Epinephrine into the blood
Describe the rest and digest (parasympathetic) response.
- Have plenty of oxygen
- Heart beating slowly
- BP is low
- Digesting food (intestines getting blood)
- Getting fuel from GI tract
Describe the fight or flight (sympathetic) response.
- Need lots of oxygen (goes to muscles)
- Heart pumping fast and hard
- BP is higher
- Not worried about digestion
- Need the fuel to run with
If you are being attacked, what happens to the pupils?
Dilate
If you are being attacked, what happens to the lens?
Flattens
