1- Introduction to the Nervous System Flashcards
State some of the functions of the nervous
- To detect changes in both the external and internal environment
- To receive sensory input
- To relay information and analyse it
- To initiate appropriate responses
What are neurones?
They are the most basic unit of the nervous system
They are cells
What is the role of neurones?
To convey information via electrical signals
It receives, integrates and transmits electrical information
What are the 3 main types of neurones?
- Afferent/sensory
- Efferent/ Motor
- Interneurones
Describe afferent neurones
They carry electrical information from the receptors to the CNS
(Brings input to the CNS)
Describe efferent neurones
They carry electrical information from the CNS to the peripheral effectors
Describe interneurones
Found only in the CNS
They link the afferent neurones with the efferent ones
Describe the cell body of neurones
Inside the cell body there is a nucleus which all the cells organs
What makes neurones different to other cells?
- They have dendrites
2. It has an Axon
Describe dendrites
They are projections fro the cell body that receive information
Describe axons
It is in-charge of sending information the cell body receives to the other neurones
What is a synapse
This is where neurone 1 meets neurone 2
It is where 2 neurones communicate
What is the neurone before the synapse called?
Pre synaptic cells
What is the post synaptic cell
The neurone after the synapse
What happens at the synapse?
Neurotransmitters are released from the presynaptic neurone
These neurotransmitters are picked up by the post synaptic neurone
What are neurotransmitters?
Chemical messengers that send electrical signals to the post synaptic neurone
What is the Nervous system split into?
- The central nervous system
2. The peripheral nervous system
What is the CNS made up of?
Only the brain and spinal cord
What can the peripheral nervous system be slit into?
- The somatic nervous system
2. The autonomic nervous system
What does the somatic nervous system control?
It controls the external actions of skin and muscle
What does the autonomic nervous system control?
It controls internal activities of the organs and glands
What can the autonomic nervous system be further split into?
- The sympathetic nervous system
2. The parasympathetic nervous system
Define the term anterior
Anything towards the front of the body
Define the term ventral
Anything towards the front of the body
Define the term posterior
Anything towards the back of the body
Define the term dorsal
Anything towards the back of the body
Define the term rostral
Towards the head (Above)
Synonymous with superior
Define the term caudal
Towards the feet/ tail (below)
Synonymous with inferior
What is the coronal plane?
An imaginary plane dividing the body into dorsal (posterior) and ventral (Anterior) parts
What is the sagittal plane?
An imaginary plane dividing the body into left and right sides
What is the transverse plane?
An imaginary dividing line that separates the superior and inferior sections of the body
What does the CNS develop from?
A neurone tube that develops a bend at the superior rostral part of the head
In the brain what is dorsal synonymous with after the bend forms?
Superior
In the brain what is ventral synonymous with after the bend forms?
Inferior
In the brain what is posterior synonymous with after the bend forms?
Caudal
In the brain what is rostral synonymous with after the bend forms?
Anterior
Describe the cerebrum in the brain
The cerebrum is a large part of the brain containing the cerebral cortex as well as several subcortical structures
What are some of the sub divisions of the CNS?
- The cerebrum
- The brain stem
- The cerebellum
- The spinal cord
What can the cerebrum be divided into?
The outer brain (Telencephalon)
The inner brain (Diencephalon)
What can the outer brain also be called?
Telencephalon
What can the inner brain also be called?
Diencephalon
What can the brainstem be further divided into
The midbrain (top portion) Pons (middle brown portion) Medulla oblongata (inferior part)
What is the role of the brain stem?
Links our brain to the spinal cord
What is the medulla oblongata directly connected to?
The spinal cord
Describe the cerebellum
Is translates to the ‘small brain’
It is found at the back below the cerebrum
Describe how the CNS forms in the embryo
As a hollow straight tube
It forms 3 swellings and a bend at the rostral end
What are the 3 swellings that develop in the hollow tube in utero responsible for?
They are responsible for developing into the different parts of the brain
What are the 3 swellings that develop in the hollow tube in utero called?
- The forebrain (Prosencephalon)
- The midbrain (Mesencephalon)
- The hindbrain (Rhombencephalon)
What is another name for the forebrain?
Prosencephalon
What is another name for the midbrain?
Mesencephalon
What is another name for the hindbrain?
Rhombencephalon
Anything at the caudal end of the tube develops to form what?
The spinal cord
What does the central canal develop into?
It remains and develops into expansion fluid
What happens once the first 3 swellings have formed in the embryo?
These 3 swellings become 5 swellings
What are the 5 new swellings that form after the first 3 swellings called?
- Telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myelencephalon
What does the Prosencephalon (forebrain) swelling turn into?
Telencephalon
Diencephalon
What does the diencephalon give rise to?
Our optic vessels
What does the Mesencephalon (middle brain) swelling turn into?
Stays the same
What does the Rhombencephalon (hind brain) swelling turn into?
Metencephalon
Myelencephalon
What does the telencephalon give rise to in the mature brain?
The cerebral hemisphere
What does the Diencephalon give rise to in the mature brain?
The Diencephalon
ie the thalamus and hypothalamus ect
What does the Mesencephalon give rise to in the mature brain?
The midbrain
What does the Metencephalon give rise to in the mature brain?
The pons
The cerebellum
What does the Myelencephalon give rise to in the mature brain?
The medulla oblongata
Summarise the 5 steps involved in forming the central nervous system
- Adult CNS from hollow neural tube.
- Five swellings develop at rostral end.
- Each forms a subdivision of adult brain.
- Rest of tube forms spinal cord.
- Cavity of tube persists in different degrees of expansion throughout tube
What is grey matter made up of?
- Cell bodies
2. Points of synapses
What is white matter matter made up of?
Axons and Tracts
Whta is the brain divided into?
The left and right hemisphere
What actually separates the left and right hemisphere?
A longitudinal fissure
also known as the superior sagittal fissure
What connects the right and left hemisphere?
The corpus callosum
Describe the corpus callosum
It is a structure that connects the right hemisphere with the left
It is found deep in the brain
It is a huge band of white matter
Where is the cerebellum formed?
Behind the brainstem and below the cerebral hemisphere
What are the 4 lobes the brain is split into called?
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
How many cranial nerves do we have?
12 Pairs
What do the 12 cranial nerves supply?
Supplies the head and neck structures
Why is the surface of the brain highly folded?
To increase the surface area
What are the folds in the brain called?
A Gyrus
plural Gyri
What are grooves in the brain called?
A Sulcus
plural sulci
Where do we find grey matter?
Under the cerebral surface and deep in the brain
What are found in the ‘empty’ spaces in the brain?
Cerebral spinal fluid
CSF
What is the spinal cord protected by?
The bones in our vertebral column
What are the 4 main segments of the spinal cord?
- Cervical Segment
- Thoracic Segment
- Lumbar Segment
- Sacral Segment
How many bones make up our cerebral column?
33
What are the different types of bone that make up our vertebral column?
thoracic lumbar sacrem coxix cervical
Does the spinal cord finish before or after the vertebral column?
Before
What do we have at the end of the vertebral column when the spinal cord ends ?
The cauda equina:
A lot of nerves at the bottom of our spinal cord
How many segments can the spinal cord be split into after the 4 main ones?
31
Roughly what are the main 31 segments of the spinal cord?
8 Cervical (C1-C8) 12 Thoracic (T1-T12) 5 Lumbar (L1-L5) 5 Sacral (S1-S5) 1 coccygeal (Co1)
How many spinal nerves do we have?
31 pairs of spinal nerves that form the 31 segments
What does each spinal cord segment give rise to?
1 Pair of segmental spinal nerves
What do the 31 pairs of spinal nerves form?
The peripheral nervous system (PNS)
Where is the white matter found in the spinal cord?
The outside
Where is the grey matter found in the spinal cord?
The inside
What can the grey matter in the spinal cord be divided into?
Into horns:
- The dorsal horn
- The lateral horn (T1-L2) (S2-S4)
- Ventral horn
What does the dorsal horn of the GREY matter in the spinal cord contain?
Cell bodies of sensory neurones
What does the lateral horn of the GREY matter in the spinal cord contain?
Cell bodies ion our autonomic neurones
What does the ventral horn of the GREY matter in the spinal cord contain?
Cell bodies of motor neurones
Where does the lateral horn only exist
At the T1-L2 level and the S2-S4 level
What is white matter in the spinal cord divides into?
Columns:
- Dorsal white column
- Lateral white column
- Ventral white column
- Ventral white commisure
What does the Dorsal white column of the WHITE matter in the spinal cord contain?
Nerve axons responsible for bringing sensory fibres to the spinal cord
What does the lateral white column of the WHITE matter in the spinal cord contain?
Nerve axons responsible for bringing motor fibres to the spinal cord
What does the ventral white column of the WHITE matter in the spinal cord contain?
Nerve axons responsible for bringing motor and sensory fibres to the spinal cord
What does the Ventral white commisure of the WHITE matter in the spinal cord contain?
Allows communication between both halves of the spinal cord
What makes up the peripheral nervous system
The 31 pairs of spinal nerves
What does the somatic division of the peripheral nervous system control?
Control external actions of the skin
Which type of neurones carries electrical signals from the CNS to the peripeheral effectors?
Efferent/ Motor neurones
Which secondary swelling gives rise to the cerebral hemisphere?
The telencephalon
What are the fibres emerging from the spinal cord called?
Rootlets
How many rootlets do we have?
2: The dorsal rootlet and ventral rootlet
What do the the dorsal and ventral rootlet converge to form?
The dorsal and ventral root
What is the dorsal root accompanied by?
The dorsal ganglion
What does a ganglion contain?
Cell bodies
When the dorsal and ventral root converge what do they form?
The segmental spinal nerve
Describe the pathway of a somatic sensory neurone
They are afferent fibres
- They enter the spinal nerve
- Go through the dorsal root
- Synapse at the ganglion
- Connect to other neurones at the ganglion
- Enter the dorsal horn
Describe the pathway of a somatic motor neurone
They are efferent fibres
- Start at the cns specifically from the ventral grey matter
- Goes through the ventral horn
- Passes the ventral root
- Goes to whichever muscle we want to control
Where are inter neurones found?
In the CNS
What do inter neurones do?
Link the sensory and motor neurone
Describe the stages of a reflect arc
Stimulus Receptor Sensory neurone Inter neurone in the CNS Motor neurone Effector Response
Why is the reflex arc important?
Allows us to give a quick response
What forms the segmental spinal nerve?
The converging of the dorsal and ventral root
What is the Mesencephalon?
The midbrain
What is the inferior portion of the brainstem called?
The medulla oblongata
Which initial swelling does the Telencephalon arise from?
The Prosencephalon (forebrain)
What is the pre synaptic neurone?
The neurone before the synapse
What is the middle portion of the brainstem called?
The pons
Which secondary swelling gives rise to the midbrain?
Mesencephalon
What is the Rhombencephalon?
The hindbrain
Which neurone is only found in the CNS and what is its role there?
Interneurons
They link the afferent neurones with the efferent ones
What is the Diencephalon?
The inner brain
What Is the Prosencephalon?
The forebrain
Which secondary swelling gives rise to the pons and cerebellum?
Metencephalon
What do Cell bodies and Points of synapses make up in the mature brain?
Grey matter
Which type of neurones carries electrical signals from the receptors to the cns?
Afferent/ sensory neurones
Which initial swelling does the Metencephalon arise from?
Rhombencephalon (Hind brain)
Name the secondary vesicles in the neural tube that form the mature brain
- Telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myelencephalon
What is the neurone after the synapse called?
The post synaptic neurone
Which secondary swelling gives rise to the medulla oblongata?
Myelencephalon
What is the Telencephalon?
The outer brain
What is the longitudinal fissure?
A groove that separates the left and right hemisphere
What is the top portion of the brainstem called?
The midbrain
Which initial swelling does the Myelencephalonarise from?
Rhombencephalon (hind brain)
What allows for communication to occur between both halves of the spinal cord ?
the Ventral white commisure of the WHITE matter in the spinal cord
What does the spinal cord develop from?
the caudal end of the hollow tube in utero
What gives rise to our optic vessels?
The diencephalon
What is found on the outside of the spinal cord?
White matter
Where are the Cell bodies of sensory neurones found?
Dorsal horn of GREY matter in the spinal cord
Where are Nerve axons responsible for bringing motor and sensory fibres to the spinal cord found?
the ventral white column of the WHITE matter in the spinal cord
Which initial swelling does the Diencephalonarise from?
The Prosencephalon (forebrain)
Name the primary vesicles in the neural tube that form the mature brain
- The forebrain (Prosencephalon)
- The midbrain (Mesencephalon)
- The hindbrain (Rhombencephalon)
Which secondary swelling gives rise to the thalamus and hypothalamus ect?
The Diencephalon
What do Axons and Tracts make up in the adult brain?
White matter
Where are Nerve axons responsible for bringing motor fibres to the spinal cord found?
the lateral white column of the WHITE matter in the spinal
Where are the Cell bodies of our autonomic neurones found?
Lateral horn of GREY matter in the spinal cord
What is the superior sagittal fissure?
A groove that separates the left and right hemisphere
What is found behind the brainstem and below the cerebral hemisphere?
The cerebellum
What are gyri?
A ridge or fold between on the cerebral surface in the brain.
What are sulci?
Grooves in the brain
What is found on the inside of the spinal cord?
Grey matter
Where are Cell bodies of motor neurones
Ventral horn of GREY matter in the spinal cord
Where are Nerve axons responsible for bringing sensory fibres to the spinal cord found?
Dorsal white column of the WHITE matter in the spinal cord