7- The autonomic nervous system Flashcards
What is anxiety?
A feeling of worry, nervousness, or unease, typically about an imminent event or something with an uncertain outcome.
What are some of the physical symptoms of anxiety?
Racing heart
Heavy breathing
Sweating
Dry mouth
What are the 2 divisions of the nervous system?
- Central nervous system (brain and spinal
2. Peripheral nervous system
What is the peripheral nervous system split into?
- The somatic nervous system
2. The autonomic nervous system
What does the somatic nervous system control?
Controls external actions of skin and muscles
What does the autonomic nervous system control?
Controls internal actions of organs and glands
What can the autonomic nervous system be split into?
- Sympathetic
2. Parasympathetic
What are somatic motors?
Efferent fibres travelling TO the striated (skeletal) muscle
What are somatic sensory pathway?
afferent fibres COMING from receptors
How many spinal nerve do we have?
31
What type of reaction results from the autonomic nervous system?
A largely involuntary reaction
What does the autonomic nervous system monitor?
Monitors conditions in the internal environment to maintain homeostasis
What is homeostasis?
Homeostasis is a dynamic balance between the sympathetic and parasympathetic nervous systems
What is that parasympathetic nerve system describes as?
‘Rest and digest’
What is that sympathetic nerve system describes as?
‘Fight or flight’
What are the 2 divisions of the autonomic nervous system?
Sympathetic and Parasympathetic
From which branch of the ANS do most visceral organs receive information from?
Most visceral organs receive both sympathetic and parasympathetic
What type of effect to the parasympathetic and sympathetic nervous systems have on each other?
They Exert an antagonistic effects
What does the parasympathetic nervous system sustain?
Sustains normal bodily functions
Conserves and restores energy
What does the parasympathetic nervous system prepare us for?
Rest and Digest
What do visceral organs send?
sensory afferent fibres to the CNS
What do visceral organs receive?
Motor Efferent fibres from CNS
What are autonomic (visceral) motor fibres and where do they go?
They are efferent fibres that travel to smooth muscles, cardiac muscle or glands
What are autonomic (visceral) sensory fibres and where do they come form?
They are afferent fibres from sensory receptors in an internal organ
Where is the lateral grey horn present?
Between the levels of:
T1-L2
S2-S4
From where do visceral motor neurones exit the spinal cord?
Via the lateral grey horn
How many neurones makes up the efferent system of the autonomic nervous system?
2 neurone chain
Name the 2 neurones involved in transmitting efferent signals in the ANS
- Preganglionic neurone
2. Postganglionic neurone
Where is the preganglionic neurone that transmits efferent signals in the ANS found?
Somewhere in the CNS (Either the brainstem or spinal cord)
Where is the postganglionic neurone that transmits efferent signals in the ANS found?
Somewhere in the PNS
Why are the Preganglionic neurone and Postganglionic neurone given these name?
Because they synapse at the autonomic ganglion
Where is the autonomic ganglion found?
In the PNS
Where is sympathetic outflow coming from ?
Comes from the levels T1-L2 (Thoracolumbar outflow)
Where is parasympathetic outflow coming from ?
Brainstem: cranial nerves III,VII, IX, X
Spinal cord: S2-S4
Describe the structure if the sympathetic nervous system
Organised ganglia in sympathetic chain, and prevertebral ganglia
Where are the ganglia located In the parasympathetic nervous system?
Near the effector organ
Compare the sizes of the pre and post ganglionic efferent neurones in the sympathetic nervous system,
Short preganglionic neurone
Long post ganglionic neurones
Compare the sizes of the pre and post ganglionic efferent neurones in the PARAsympathetic nervous system,
Long preganglionic neurone
Short post ganglionic neurones
What type of effect does the sympathetic nervous system have?
A widespread effect
What type of effect does the PARAsympathetic nervous system have?
A localised effect
Which cranial nerve can the preganglionic neurone travel through in the parasympathetic pathway ?
Cranial nerves III, VII, IX, X
Where does the preganglionic neurone travel through it originated from the sacral spinal cordin the parasympathetic pathway?
Will travel in spinal nerves 2, 3 or 4
What neurotransmitter is involved in the parasympathetic nervous system?
Acetylcholine
What is a neurotransmitter?
A chemical that is released by a neurone at the site of synapse
It is received by another neurone or organ it it exerts an effect on this neurone or organ
What is the ratio of preganglionic to postgagnlionic neurones in the parasympathetic nervous system?
1pre :1post
What allows us to have a localised effect from the parasympathetic nervous system?
The fact that there is a ratio of 1 preganglionic to 1 postganglionic neurone
Name the 3rd cranial nerve
Oculomotor nerve
Where does 3rd cranial nerve deliver parasympathetic fibres to?
The pupils
What action does the 3rd cranial nerve do in the parasympathetic nervous system?
Constricts the pupils
Name the 7th cranial nerve
The facial nerve
Where does 7th cranial nerve deliver parasympathetic fibres to?
To salivary and lacrimal glands
What action does the 7th cranial nerve do in the parasympathetic nervous system?
Increases salivation
Name the 9th cranial nerve
The Glossopharyngeal nerve
Where does 9th cranial nerve deliver parasympathetic fibres to?
To salivary glands
What action does the 9th cranial nerve do in the parasympathetic nervous system?
Increases salivation
Name the 10th cranial nerve
The vagus nerve
Where does 10th cranial nerve deliver parasympathetic fibres to?
To cardiac, pulmonary and digestive system
What action does the 10th cranial nerve do in the parasympathetic nervous system?
Decrease HR
Constricts the bronchi
Increase digestive function
Which cranial nerve is the main parasympathetic nerve of the viscera of the trunk
The vagus nerve (cranial nerve X)
Which parasympathetic nerves come our of the spinal cord?
Pelvic splanchnic nerves
Which organs are supplied by the Pelvic splanchnic nerves ?
The large intestine
The bladder
The reproductive organs
What effect the parasympathetic nervous system have on the bladder?
Allows urination
What effect the parasympathetic nervous system have on the reproductive organs?
Causes arousal
What is the origin of the sympathetic nervous system?
Thoraco-lumbar origin
T1-L2 spinal segments
What neurotransmitter does the preganglionic neurone release?
Acetylecholine
What neurotransmitter does the preganglionic neurone release?
noradrenaline/ norepinephrine (to the target organ
Where does the pre ganglionic neurone synapse in the sympathetic nervous system?
In the sympathetic chain
Which gland on the sympathetic nervous system does not receive the neurotransmitter norepinephrine?
The sweat glands
What does the sympathetic nervous system have a widespread effect?
Because there’s a 1 pre: many post ganglionic ratio
What is the sympathetic trunk?
It is an Interconnected chain of autonomic ganglia
Where is the sympathetic trunk located?
either side of the entire vertebral column (paravertebral)
What happens at the sympathetic trunk?
It is the site of synapse between sympathetic pre-ganglionic and post ganglionic neurons
What is special about the chain nature of the sympathetic trunk?
It allows for sympathetic signals to be sent Above and below the levels of T1-L2
This allows for information to go into the head and neck area or below to the pelvic area
Where do al preganglioninc fibres leave the spinal cord?
In segmental spinal nerves T1-L2 ONLY
What effect do sympathetic fibres have on the salivary glands?
Inhibits salivation
What effect do sympathetic fibres have on the pupil?
Dilates them
What effect do sympathetic fibres have on the heart?
Increases HR
What effect do sympathetic fibres have on the lungs?
Causes bronchodilation
What effect do sympathetic fibres have on the digestive system?
Decreases digestion
What effect do sympathetic fibres have on the bladder?
Prevent urination
What effect do sympathetic fibres have on sexual organs?
Prevents sexual arousal
What are the 3 things the preganglionic neurone can do in the sympathetic nervous system?
1 .It can synapse at entry level of the paravertebral (sympathetic) ganglia
2. It can Pass through the sympathetic trunk without synapsing – to synapse in prevertebral (collateral) ganglia
3 It can Ascend or descend in the trunk to synapse in the trunk
How do we sense changes in the viscera in sympathetic nervous system?
Via autonomic (visceral) sensory
What are autonomic (visceral) sensory fibres?
They are afferent fibres from sensory receptors in an internal organ, glands and blood vessels
From where do afferent fibres enter the spinal cord?
Via the dorsal root to enter the dorsal grey horn
What causes referred pain?
Both somatic sensory afferents and visceral afferent enter the spinal cord via the dorsal root and horn
As info is coming in the same place the brain may not be able to differentiate where the signal is coming from (the skin or organ?)
Name the different levels of the ANS
cerebral hypothalamus -> Brainstem centres -> Spinal cord centres
What is the cerebrum in charge of?
Overall it is in charge of emotional responses
What are the brainstem centres in charge of?
Overall it is in charge of the regulation of the autonomic nervous system
What is the Hypothalamus in charge of?
Regulates cardiovascular respirator and swallowing functions
What are the Spinal cord centres in charge of?
urination, defaecation, erection, ejaculation
