Autonomic Nervous System Flashcards
The CNS is comprised of:
pre-ganglionic ganglia
The PNS is responsible for:
Synapse of post ganglionic cells
The ANS functions without:
Conscious effort
During SNS activation, the adrenal medulla promotes secretion of:
Adrenaline and noradrenaline
During PSNS activation, the endocrine pancreas secretes:
Insulin and glucagon
During SNS activation, the endocrine pancreas promotes secretion of:
Insulin
Afferent neurons…
Are sensory, travel to the ventral horn
Efferent neurons…
Are motor, travel down to the dorsal horn
Define ganglia:
A bundle of nerves that sit within the ganglia and give-off post-ganglionic axons
The SNS has its motor neurons within the:
Thoracic and Lumbar regions
Within the SNS, ganglia are ____ to the spinal cord
Proximal
Within the SNS, pre-ganglionic axons are shorter than post-ganglionic axons. T/F
True
GI tract, urinary bladder and genitals activity decrease upon activation of the…
SNS
The PSNS has its motor neurons within the ____
Brain stem and sacrum
Within the PSNS, the ganglia are proximal to…
The organ innervated
Autonomic Ganglia:
Bridges the central motor neurons to effector organs
Post-ganglionic axons terminate at…
Varicosities embedded within smooth muscle
Single-unit smooth muscle cells are innervated by ___
Gap junctions
For contraction of multi-unit smooth muscle cells ____
Each cell must be individually innervated
i.e. within the eye
Autoinhibition:
Neurotransmitters act back on presynaptic membrane to inhibit further release
Activation of post-Synaptic adrenergic receptors (α1) by sympathetic nerve varicosities results in _____
Increased vasoconstriction.
What is the minimum number of neurons that neural signals must propagate through from a visceral sensory receptor to a visceral effector organ?
3
From a visceral sensory receptor, neural signals will travel through a sensory neuron (1) to a pre-ganglionic neuron (2) in the ventral horn of the spinal cord. This pre-ganglionic neuron will then synapse with a post-ganglionic neuron (3) in an autonomic ganglion. Finally, the post-ganglionic neuron will innervate a visceral effector organ.
Single-unit smooth muscle cells are able to contract simultaneously in a coordinated manner. Aside from the digestive system, where else in the body would single-unit smooth muscle cells exist?
Uterus and Bladder
Direct acting cholinergic agonists bind to ____
Muscarinic or nicotinic receptors –> release acetylcholine
Indirect acting reversible cholinergic agonists bind to ____
Acetylcholine
Which neurotransmitters is responsible for the activation of sweat glands under sympathetic activation?
Acetylcholine
Pre-ganglionic neurons release ____ to act on ____
Acetylcholine to act on nicotinic receptors
PSNS post-ganglionic fibers release ___ to act on ___
Release ACh onto muscarinic receptors on the postsynaptic target organs
SNS post-ganglionic fibres release ____ to act on ____
Adrenaline and noradrenaline to act on adrenergic receptors
ATP also releases Na+ and acts faster in inducing contractions of the smooth muscle –> activating post-synaptic voltage-gatedCa2+ channels. T/F
True
Within the neuroendocrine compartment, SNS pre-ganglionic fibres innervate _____
Chromaffin cells within adrenal medulla
Chromaffin cells promote secretion of:
Na+ and anions
Global broadcasting of the sympathetic nervous system activation is achieved by:
Chromaffin cells, as they reside near blood vessels –> where hormones are released for systemic circulation;
Muscurinic receptors are agonized by:
Acetylcholine
Nicotinic receptors are agonized by ____
Acetylcholine or nicotine
Muscrurinic Receptor1: Located in gastric glands, _____
Gq coupled –> incr. Intracellular calcium –> incr. contraction, secretion, neurotransmission
Muscrurinic Receptor2: Located on cardiac cells, ____
Gi coupled –> opening of K+ channels, hyperpolarisation and decr. HR
Muscrurinic Receptor3: Located in smooth muscle i.e. Lungs, eyes, endocrine glands and the GI tract
Gq coupled –> incr. Intracellular calcium –> contraction, secretion, neurotransmission
Muscrurinic Receptor 4, Muscrurinic Receptor 5: Not yet distinguished, however, are within the…
PSNS
When nicotinic receptors are activated, they…
are permeable to Na+ and K+; rapid depolarization of the cell
Nicotinic receptor1 are located at the….
Neuro-muscular junction
Nicotinic receptor2 are located at the…
Post-ganglion neuron
Adrenergic receptors are GPCRs and are agonized by…
Na+ and A-
Which receptors are found in the parasympathetic NS?
Nicotinic and Muscarinic
The Enteric NS is dependant on the…
CNS
The myenteric plexus is located within the:
Muscularis externa
The myenteric plexus controls ____ and consists of _______
Digestive tract motility
Ascending neuronal network &
Descending neuronal network
The submucosal plexus is found within the:
Mucosa and submucosa
The sub-mucosal plexus controls the:
Secretion, absorption, and local muscle movements
For peristalsis –> bolus of food is travelling from Oral to Aboral
The stretching of intestinal wall stimulates neurons within the myenteric plexus. Simultaneously, the chemicals within the food stimulate sensory neurons within the submucosal plexus.
Both sensory neurons branch into the ascending and descending networks.
Ascending neuronal network release excitatory neurotransmitters (ACh acetylcholine and SP substrate P) to the circular muscle behind the bolus; causes contraction of circular muscle
Descending neuronal network release inhibitory neurotransmitters (NO nitric oxide, VIP vasoactive intestinal peptide and ATP adenosine triphosphate) to longitudinal muscle to cause relaxation.
Ascending neuronal network within the myenteric plexus release….
Excitatory neurotransmitter, acetylcholine
Descending neuronal network within the myenteric plexus release….
Inhibitory neurotransmitters Nitric oxide, vasoactive intestinal peptide, and ATP
Gastric Mixing:
Physical and chemical breakdown
Segmentation:
Contractions move food in both directions
Peristalsis:
One-way motion towards the anus
Migrating Motor Complex:
Electrochemical activity within GI smooth muscle between meals
From the CNS, the vagus innervation initiates the Pre-ganglionic PSNS fibers to…
- Pre-synaptic synapse at ganglia
- Release acetylcholine
- Post-ganglionic fiber carries ACh from nicotinic receptor to muscarinic receptor
- Released onto heart and vessels
The Post-sympathetic adrenergic fibers initiate:
- Pre-synaptic fibers synapse at the ganglia
- Release ACh
- Post-ganglionic fiber carries ACh from nicotinic receptor
- Release norepinepherine onto α- adrenoceptor and β-andrenoceptors to the heart and vessels
The Post-sympathetic dopaminergic fibres initiate:
- Pre-synaptic fibres synapse at the ganglia
- Release ACh
- Post-ganglionic fiber carries ACh from nicotinic receptor
- Post-sympathetic dopaminergic fibers release dopamine onto dopaminergic receptor
at renal vessels
The adrenal fibres initiate:
- Pre-synaptic fibres synapse at adrenal ganglia
- Release ACh to nicotinic receptor
- Epinephrine an norepinepherine act on the α-adrenoceptor and the β-adrenoceptor at the heart and vessels
Activation of post-synaptic adrenergic receptors (alpha 1 receptors) by sympathetic nerve variscoties results in…
Increased vasoconstricion
The enteric system is:
- Part of the autonomic NS
- Involved in the coordination of peristalsis
- Composed of neurons in the muscle and submucosa of the guy
- ACh is a key neurotransmitter
The enteric system is influenced by the SNS or PSNS. T/F
True
Voluntary defecation is due to…
- Stimulation of stretch receptors in the rectum
- PSNS stimulation of smooth muscle at internal anal spincter
- Voluntary stimulation of external spincter via motor neurons
- An increase in abdominal pressure
Within the SNS reganglionic neurons may have their cell bodies in spinal cord segments S2 through S4. T/F
False
Within the SNS, ganglia are located relatively close to the central nervous system. T/F
True
