Nervous System, Spine And Brain Flashcards
Main function of the nervous system -
Detect changes in internal/external environments and therefore bring response in muscle,organs and glands
What are the two different nervous systems and what are they each made up of?
Central nervous system (CNS) - brain and spinal cord
Peripheral nervous system (PNS) - outside brain and spinal cord
Neurons, function and common characteristics:
Basic structural and function untis of the nervous system is the nerve cell/neuron
All neurons share these common characteristics:
Single cell body (soma)
Axon - allow AP’s to travel;
Dendrites - receive info (have neurotransmitters)
Synaptic terminals (axon terminals)
Myelin -
What are the gaps between myelin?
What forms myelin?
The insulting layer of axons
Made primarily of lipids
AP’s travel quickly and more effectively in myelinated compared to unmyelinated
Gapes between myelin is called the nodes of ranvier - contain sodium channels
Swchann cells form myelin - peripheral
Oligodendrocyte cells from myelin - CNS
Neurone types
Biopolar neurone -
Pseudounipolar neurone -
Multipolar -
Biopolar - sensory neurone (uncommon - found only in nasal cavity, retina and within ear)
Pseudounipolar - sensory neurone (cell body in centre of neurone)
Multipolar - motor neurone and inter neurones. Most common type in the CNS (cell body at end of neurone)
Motor neurones divided into two sub-division
1) upper motor neuron (UMN)
2) lower motor neuron (LMN)
1) upper - transmit info from brain to lower motor neurones and inter neurones in the brain stem and spinal cord. Part of the CNS
2) lower motor neurones- neurons with cell bodies in spinal cord or brain stem whose axons directly Innervation skeletal muscle. Part of PNS
White matter -
Grey matter -
Which does the CNS contain?
White - contains axons of the neurones (covered in myelin,fatty substance therefore is white) makes up 60% of brain
Grey - contains cell body of neurones (not covered in myelin) makes up 40% of brain
CNS has both grey and white matter
What are the three actions of the nervous system?
1 - receiving and transmitting sensory input (PNS)
2- centra processing/integration
3- motor output (PNS)
AP’s - nerve impulse
How is a neurone polarised ?
Body - electrically neutral. Some areas are more positive/negative than others
Currents indicate the flow of postive/negatively charged ions across the resistance of your cell membrane
Resting neurone is more negative inside
Resting potential - 70mv
Sodium ions sit outside
Potassium ions sit inside neurone, but there is less of them therefore outside is more positive than inside
Polarized - negative membrane potential
AP’s and nerve impulse
Role os sodium potassium pump =
2x potassium in cell and 3x sodium out of cell, therefore creates a concentration difference
This creates an electrochemical gradient
AP’s and nerve impulse
Ion channels - large proteins:
1) voltage-gated channels -
2) ligand-gated channels -
3) mechanically gated channels -
1) open and close in response to changes in membrane potential
2) open when neurotransmitter latches onto it’s receptor
3) open in response to physical stretching of the membrane
When open - ions flood in to even out electrochemical gradient
AP’s and nerve impulse
Stages of an AP -
Neurone must be depolarised for an AP to occur
1) resting -70mv. Ion channels are closed
2) stimulus occurs - sodium channels open therefore increasing charge inside membrane. -55mv is the threshold for an AP to occur - all or nothing law
3) if reached, voltage-gated sodium channels open therefore sodium floods in. +40mv reached - AP
4) repolarisation occurs - voltage gated potassium channels open and therefore flow out neurone
5) brief period of hyper-polarisation
6) all channels closed and resting restored
AP’s and nerve impulses
What is a refractory period?
A period whereby unable to respond to any other stimulus, no matter how strong.
Prevents signals travelling in two different directions down an axon at once
AP’s and nerve impulse
Why is myelin important ?
Synapse -
Myelin important as will conduct impulses faster
Synapse - the meeting point between two neurones. Converts APs to a different type of signal and sends it to another neurone. Some synapses are electrical - quickest
Others are chemical - takes longer but used more often and easier to control
Chemical uses neurotransmitters
AP’s and nerve impulse
What happens when an AP reaches a pre-synaptic terminal ?
Voltage gated calcium channels open and release calcium. Synaptic vesicles merge with membrane. Neurotransmitters released into synaptic cleft and bring to receptors on post synaptic neurone. Electrical is converted into chemical here
AP’s and nerve impulse
Summation -
Spatial -
Temporal -
Summation - process that determines if an action potential will be generated by the combined effects of excitory and inhibitory signals
Spatial - multiple simultaneous inputs
Temporal - repeated inputs
Depending on the total of the individual inputs, summation may/may not reach threshold voltage to trigger an AP.
Spinal cord
Myotomes -
Dermatomes -
Myotomes - group of muscles innovated by a single nerve route
Dermatomes - strip of skin innovated by single spinal nerve
What are the different categories of spinal processes and how many make up each?
Cervical spine - C1-C8
Thoracic spine - T1-T12
Lumbar spine - L1-L5
Sacral spine - S1-S5
Coccygeal nerve - C0
Name of hole in vertebrae -
Name of opening just posterior to where vertebrae are stacked on top of each other -
Vertebrae foreamen - spinal cord sits in this
Intervertebral foreamen - this I where spinal nerve routes emerge from spinal cord to innovate different areas/muscles
What protects the spinal cord?
Where does the cerebral spinal fluid sit?
Meninges - three dif ones
Pia mater - thinnest most inner one
Arachnoid matter - middle
Dura matter - outer
Fluid sits between the Pia and arachnoid (subarachnoid space) - liquid protection
Spinal tracts
Afferent-
Efferent -
Name the tracts that make up each:
Afferent - ascending SENSORY spinal tracts
Called -dorsal column, spinocerebellar, spinothalamic
Efferent - descending MOTOR spinal tracts
Called - cortico spinal tract (lateral), rubrospinal, reticulo spinal, vestibule spinal, tectospinal and cortico spinal (anterior)
