The Brain and Nervous system Flashcards
Function of the Sympathetic autonomic Nervous System-
-thoracic and lumbar regions-increase blood pressure /heart rate etc
Function of the parasympathetic autonomic nervous system-
-Cranial and Sacral , Slows blood pressure/heart rate etc
Layers of a nerve -
Epineurium - Perineurium - Endoneurium.
- Draw a Neurone
…..
Outline a nerve impulse -
- Stimuli = sodium channerls open
- na+ rush into cell
- Depolarisation
- Equilibrium
- Na channels close
- Potassium channels open
- K+ moves out of the cell
- Repolarisation occurs
- K channels are slow to close
- Hyperpolarisation occurs
What is the resting potential of a neurone?
-70mV
Continuous vs saltatory conduction
When an action potential in an axon spreads to a neighboring region of its membrane by a series of small steps eg the opening of na+ channels, the process is called continuous propagation. When it propagates by jumping from one site eg nodes of ranvier to another along the axon, the process is called saltatory propagation
Give the role of chemical synapses-
- Presynaptic cell releases naurotransmitters
- Act on the postsynaptic cell
- Neurotransmitters can excite or inhibit
- Neurotransmitters - Acetylcholine , Serotonin, Norepinepherine , dopamine , GABA
Give the mechanism for the transmission of neuro-transmitters -
- Transmitters is synthesised and then stored in vesicles
-Action potential in presynaptic terminal
-Depolarisation causes voltage-gated ca2+ channels
-Influx of ca2+
-causing vesicles to fuse with presynaptic membrane.
-Transmitter is released into synaptic cleft
-Transmitter binds to receptor molecules in postsynaptic membrane
-Postsynaptic current causes excitatory or inhibitory postsynaptic potential that changes the excitability of the postsynaptic cell.
-
Types of damage to neurone-
1- Chromatolysis- occurs shortly after axon damage.
2-Wallerian degenerarion- distal portion degrades
3- Axon regeneration- intact neurolemma cells divide , formation of regeneratio tube, nex axon will form
4- Re-Myelination , eventually myelin reforms too
Types of injury to neurone-
- Transient ischaemia - lack of oxygen
- Neuropraxia -Compression , take up to 6-8 weeks
- Axonotmesis- Axon is damaged
- Neurotmesis - Severed nerve , can be repaired through surgery.
Outline the role of the Frontal lobe in the brain-
- Primary motor cortex
- Premotor cortex
- Control of behaviour
- Personality/emotion
- Memory
- Broca’s area - speech
- premotor area- Initiation/planning of movement
- Primary motor cortex- Voluntary movement.
Outline the role of the Parietal lobe-
- Somatic sensation
- Sensory Cortex
- Origin , shape , pressure , texture
- Body awareness and spatial awareness
Outline the role of the temporal lobe-
- Interpretation of speech and sound
- primary auditory area
- Wernickes Area - determines if sound is speech , music or noise , interprets meaning of speech
- Memory
Outline the role of the Occipital lobe-
- Visual Input
- Intensity of light and dark , shape of movement of object
- relates past visual experiences with recognition and evaluation
Outline the role of the Brain mid stem-
- Midbrain
- Pons
- Medulla
- Sensory pathways
- motor pathways
- important control centres
- Nuclei of cranial nerves
Name 4 Cranial Nerves-
- Optic II
- Facial VII
- Vagus X
- Olfactory I
Give the components of the diencephalon-
- Thalamus - sensory relay station
- Hypothalamus - Homeostasis , autonomic system and pituitary gland.
Give the role of the Limbic system -
- controlling emotion , response to a given situation and memory
- Group of structures - Cingulate glands, Hippocampus, amygdala , mammillary bodies
Give the role of the Cerebellum-
- Interaction between cerebellum and motor areas of the brain , produces smooth coordinated movement.
Give the sensory and ascending tracts-
- Dorsal column
- Spinocerebellar tract
- Spinothalamic tract
Give the motor and descending tracts-
- Corticospinal (anterior and lateral)
- Rubrospinal
- Reticulospinal
- Olivospinal tract
- Vestibulospinal tract
Outline the role of the dorsal column
-Fasciculus gracilis
-Fasciculus Cuneatus
-Sensory information
- First order neurone brings the spinal from
the receptor to the medulla taken over by second order nerve to the thalamus - third order to sensory cortex front of the periatal lobe.
Outline the role of the Spinothalamic tract
- Pain
- To the thalamus
- Temp
- Synapses straight away and crosses , first order neurone stops in spinal cord , second order in thalamus , third order to front of periatal lobe.
Give the role of the Spinocerebellar tract-
- Cerebellum
- Where we are in space
- Doesn’t cross , Carries up on the same side
- Right to right left to left
Give the role of the Corticospinal tract-
- Motor cortex - back of frontal lobe
- Lateral and anterior
- Muscles
- To medulla ,80% of fibres cross and 20% continue down to cross in the spinal cord.
Give the role of the Reticospinal tract -
- Reticular formation
- Lateral - flexor responses
- Medial - extensor responses
Give the role of the vestibulospinal tract-
- Vestibular nucleus - brain stem
- Anterior
- Controlling head and neck
Give the role of the rubrospinal tract-
- Red nucleus in the mid brain in the brain stem
- Think - fine motor movements
Outline the applications of spinal cord lesions-
- May impair motor, sensory and autonomic functions.
- 84% traumatic - Fracture dislocation.
- Non-traumatic = Spinal cord stenosis, spinal infarct etc
- Vulnerable areas = C5-C7
What is tetraplegia?
Hight lesion , impacting all 4 limbs.
What is paraplegia?
Impacting the lower limbs
Outline the role of A delta sensory neurones-
Myelinated , fast pain , 4 sub divisions , propiosception
Outline the role of C fibre sensory neurones-
non-myelinated , slow pain
Outline the role of A beta fibre sensory neurones-
highly myelinated and large diameter , mechanical stimuli , heat or cold.
Outline to process of pain registration-
- Receive - Process - Appropriate response
- Thalamus - sorting office and Limbic system - Emotional Link - Somatosensory Cortex - Sensation experienced as pain
Outline the process of pain reflex and response-
Sensory neuron within the tissue is stimulated, Conducts impulses from receptor to integrating center- first order neuron , Interneuron allowing the signal to bypass into the anterior horn of the spinal cord as well as allowing the signal to pass over the spinal cord up to the brain.
Describe pain gate theory -
The suggestion that non-painful input such as rubbing it better closes the nerve gates to painful input , preventing the pain sensation travelling the the CNS.
What is Unmodulated pain?
activation of C fibres which sends a message through the 1st and 2nd order neurones
What is modulated pain?
C fibres are activated by inhibitory neurones as the A beta fibres are also sending signals which move up the 2nd order neurone instead of C fibres
Pain gate is affected by -
- State of mind
- Encephalins and Endorphins
- Central Control- Brain can affect the gate as a response to memories and previous response strategies.
Pain - Summary
- Pain is both a sensory and emotional experience and patients past experiences , fears and anxieties.
- A - delta fibres transmit rapid , sharp , localised pain
- C fibres transmit slow , diffuse , dull pain
- Pain transmission is a result of complex peripheral and central processes
- Pain transmission can be modulated at a number of levels , including the dorsal horn of the spinal cord and via descending inhibitory pathways
- The spinothalamic and spinoreticular tracts are important ascending pain pathways
- Neuropathic pain can be spontaneous and is often described as burning, shooting or stabbing.
- Nociceptor - Somatic and visceral pain
