Autonomous nervous system Flashcards
What is the autonomous nervous system?
It is part of the PERIFERAL NERVOUS SYSTEM. It is responsible for controlling involuntary functions of the body. They regulate secretory glands, and movement of smooth muscles, and are responsible for maintaining homeostasis in the body. The HYPOTHALAMUS and the MEDULLA, have a major impact on the system.
What are the 3 components of the autonomous nervous system?
Sympathetic - fight or flight
Parasympathetic - rest and digest
Enteric - controls digestive system (can regulate internal functions without central control, and also works with CNS)
How is the nervous system split?
There is the central nervous system - the brain and brain stem
The peripheral nervous system - the spinal chord and the nerves branching out
The peripheral is split into:
The SOMATIC nervous system - involved in voluntary function
The AUTONOMOUS nervous system - involved in involuntary function
The Autonomous is split into:
SYMPATHETIC nervous system - fight or flight
PARASYMPATHETIC nervous system - rest and digest
ENTERIC nervous system - controls the digestive system
What parts of the body only have sympathetic response?
Blood vessels and secretory glands
What parts of the body only have parasympathetic responses?
Some parts of the eyelids
What are the names of the two motor neurones that stimulate the effector?
Monosynaptic and Disynaptic nerve
What is a monosynaptic nerve?
It is a somatic motor neurone that has an extended axon with it’s terminal on the effector, so there is only one synapse.
What is a disynpaptic nerve?
This is found with autonomic nerves. The reason is because there is the pre-ganglionic nerve (in the CNS) which connects to the autonomic ganglion through the pre-ganglionic axon, and the ganglionic nerve reaches the smooth muscles through the post-ganglionic axon. There are in total 2 synapsis.
Which type of autonomic neurone has a long pre-ganglionic neurone?
Parasympathetic
If the diameter of an axon is large, what effect does it have on the action potential?
It increases the velocity of the action potential
What is the advantage of large neurons, and their disadvantage? How is it mediated?
Adv - AP is faster
Disv - they take up a lot of space
Solution - myelanation - increases AP conductivity (speed) to make up for the neurones that would have been there
Why do smaller axons require greater depolarisation to drive AP and are more sensitive to local anaesthetics?
Their voltage gated NA channels are open more often in order to ensure that the AP propagates
What is lidocane used for?
It is a local anesthetic. They block ion gated Na channels to stop AP from happening
Name 3 mesenteric ganglia
Coeliac - supplies nerves to the stomach, liver, and intestines
Superior mesenteric - Intestines
Inferior mesenteric - Intestines and urinary tract
What can happen if you have injury in the cervical ganglia?
The cervical ganglia innervates organs located in head and neck inc blood vessels of brain/cranial muscles/eyes/lacrimal and salivary glands and innervate organs located in the chest cavity e.g. heart. Lungs and bronchi.
These therefore would be affected.
Think of the man in Empire called eddie
Where does the nucleus of the oculomotor nerve innervate?
Nucleus found in the MIDBRAIN
It provides parasympathetic innervation (nerves) to the IRIS and MUSCLES of the CILIARY BODY
The muscle of the eye
Where does the SUPERIOR SALIVATORY nucleus of the facial nerve supplies nerves to?
Nucleus found in the PONS
It provides parasympathetic nerves to the LACRIMAL glands (to produce tears) and SUBLINGUAL and SUBMANDIBULAR salivary glands (to produce saliva)
Nucleus ambiguus (axons travel in CN X)
Found in the MEDULLA
Parasympathetic innervation to larynx, pharynx & heart
Where does the dorsal motor nucleus of vagus nerve (CN X) innervate?
Found in the MEDULLA
Parasympathetic innervation to the lungs, pancreas, GI tract & heart
Where does the inferior salivatory nucleus of glossopharyngeal nerve (CN IX) provides nerves to?
Found in the MEDULLA
Parasympathetic innervation to parotid salivary gland (to produce saliva)
The CAROTID SALIVARY glands.
Where does the SPINAL CHORD innervate?
Parasympathetic innervation to descending and sigmoid COLON (last part of the colon), BLADDER, male and female SEX ORGANS and ERECTILE TISSUE
What is the name for the neurones that carry information towards the central nervous system?
Sensory neurones/ afferent neurons
What is the name of the neurone that carries information away from the brain/spinal cord to the muscles and glands?
Motor neurones
Can you explain the way sensory information is carried through the nervous system and the body’s response to it?
- The body recieves sensory information from 3 types of receptors: visceral, somatic and special receptors
- The information is sent to the sensory neurones, which carry the information through the spinal cord in the peripheral NS into the central nervous system
- The information is then recieved by either the HYPOTHALAMUS or the MEDULLA OBLONGATA, which processes the information
- The response is then sent to the pre-ganglionic neurones in the spinal cord (T1 to L2 for sympathetic - to sympathetic chain) or the brain stem (parasympathetic), and the information is sent to the motor neurones (in the sympathetic chain or near the efferent/target organ/tissue), to the somatic motor neurones or the post-ganglionic neurones
- The response causes the contraction of the efferent tissue
Think of the “sitting up”
What sensation are the somatic sensory receptors responsible for?
Position, touch, pressure, pain, temperature sensations
The normal senses
What sensation do the special sensory receptors provise sensation for?
Smell, taste, vision, hearing, balance
You covered all the outside so you cover…
What sensation do the visceral sensory receptors provide?
Internal organs
What are the two parts of the brain that are important in the autonomic nervous system?
Hypothalamus, and medulla oblongata
What is the sensory receptor responsible for sensing blood pressure increase?
Baro-receptor
How is blood pressure increase recieved in the nervous sytem?
The baro-receptor detects the increase in blood pressure. This takes the information to the medulla oblongata, which processes this information. The response signal to reduce blood pressure is then given to the pre-ganglionic neurones, which is the vagus nerve (cranial nerve X). The efferent response is sent to the post ganglionic neurones which then send the response to the efferent organ aka the heart, causing the reduction in blood pressure.
What type of nerves would cause postural hypotension?
Sympathetic nerves (they provide nerves to blood vessels)
What are the causes of postural hypotension?
Diabetes and syphilis damage the sympathetic fibres
Damage to these nerves can prevent muscle contraction of blood vessels, so blood pressure remains low, leading to postural hypotension
What are the symptoms of postural hypotension?
Dizziness, lighte headed, feeling faint
What nerve sympathetic fibres are affected by Horner’s syndrome?
The ones innervating muscles of eyelid, unnopposed parasympathetic drive leads to pupil constriction, decreased sympathetic drive to sweat glands.
Has to do with the eyes - reminds you of?
What are the symptoms of Horner’s syndrome
Dooping of upper eyelids, constricted pupil, loss of sweating of one side of the face
What causes Horner’s syndrome?
Interruption of sympathetic nerve supply to the eye
Lesion of hypothalamus, brain stem, cervical spinal cords (interrupts innervation to pre-ganglionic fibres), lung tumous (interrupts pre-ganglionic)
