Test 3 Flashcards
Name the four parts of the neurone and their function?
Dendrites – processes on the cell that receive connections from other neurons.
Cell body (soma) – where the nucleus and most organelles of the cell are located
Axon – a specialised structure to conduct the nerve signal to its target
Synapse – the end of the axon that passes the signal to another cell
Describe the phases of the action potential and what occurs in each phase?
- Membrane potential hits -55 mv
- Voltage gated Na+ channels open
o Na+ rushes into the cell
o Membrane is depolarised
o Membrane potential reaches +40mV
o Voltage gated Na+ channels close - At +30mV voltage gated K+ channels open,
o K+ rush in to restore the membrane charge
o Repolarisation - Pushes into hyperpolarisation
o K+ equilibrium is closer to -90mV - Neurone can’t be fired during this “refractory period”
How long does the process of the action potential take
Whole process takes about 2 milliseconds
What are channels in the cell membranes?
Neurons have cell membranes which contain ion channels. Ions can pass through these channels if they are open to change the charge on the membrane and help create electrical signals such as action potentials.
What are energy dependent channels
Energy dependent channels:
* Require energy (usually from ATP) to move ions, often against their concentration gradient.
* Sodium/potassium pumps moves 3 Na+ ions out of the cell and 2 K+ ions in.
* Results in higher Na+ outside the cell and higher K+ inside.
what are charge dependent channels
Charge dependent channels:
* Allow ions to pass based on charge.
* The sides of the channel may have a positive charge
* This will repel positive ions but attract negative ions and vice versa.
* This is called electrochemical exclusion and isn’t dependent on ion size.
what are size dependent channels
Size dependent channels:
* Only allow ions of a certain size to pass.
* The channel’s diameter may match the ion’s diameter.
what are ligand gated channels
Ligand gated channels:
* Open when a specific molecule (ligand) binds to a part of the channel.
* These are known as ionotropic receptors.
what are mechanically gated channels
Mechanically gated channels:
* Open due to physical changes like membrane distortion, common in touch receptors.
* Temperature changes may also affect these channels.
what are voltage gated channels
Voltage gated channels:
* Open in response to changes in membrane electrical charge.
* Example: Na+ channels may open at -55mV and close at +40mV.
what are leakage channels
Leakage channels:
* Randomly open and close due to intrinsic switching, allowing ions to “leak” through.
name the amino acid neurotransmitters and their roles
Glutamate – most common excitatory neurotransmitter in the body
GABA - most common inhibitory neurotransmitter in the brain
Glycine – most common inhibitory neurotransmitter in the spinal cord
name the peptide neurotransmitters and their roles
Endorphins - pain modulation
name the monoamine neurotransmitters
Serotonin
Histamine
The catecholamines
Dopamine
Adrenaline
Nor adrenaline
name the “others” neurotransmitters and their roles
Acetylcholine – memory and brain activation
Can I describe the basic roles of the neurotransmitter groups?
Amino Acids: Key for fast synaptic transmission; glutamate is excitatory, while GABA is inhibitory.
Peptides: Chemical chains or polymers of amino acids. Modulate pain
Monoamines: Organic molecules with an amino group bound to an organic acid. Involved with things like activation of the brain, emotion, consciousness and attention
Others: Memory and brain activation
describe the function of the frontal lobe and its borders
- Motor – movements, thoughts, speech
- Decision making, planning
- Motivation
- Social decisions
Border
Divided from the temporal lobe by the large sylvian fissure
divided from parietal lobe by centrsl sulcus
describe the function of the occipital lobe and its borders
- Vision
Border
Divided from the temporal & parietal lobes by arbitrary boundaries
describe the function of the temporal lobe and its borders
- Hearing
- Speech comprehension
- Emotion
- Memory
Border
Divided from the frontal lobe by central sulcus.
parietal & occipital lobes by the large Sylvian Fissure and arbitrary boundaries
describe the function of the parietal lobe and its borders
- Somatosensory (body sensation)
- Integration of sensation
- Spatial awareness
- Reading, speech comprehension
Borders
Divided from the frontal lobe by the central sulcus.
Divided from the temporal & occipital lobes by the large Sylvian Fissure and arbitrary boundaries
what are the 4 lobes of the brain
FOPT
Can I describe the differences between Grey and White matter?
Grey matter
* Grey matter contains more neuronal cell bodies
* Cell bodies are grey in colour
White matter
* White matter contains more axons
* Fibres (axons) connecting areas of the nervous system
* White colour comes from the myelin surrounding the axons
How many spinal nerves are where do they emerge from?
There are 31 spinal nerves emerging from:
* Cervical: 8 (C1-C8)
* Thoracic: 12 (T1-T12)
* Lumbar: 5 (L1-L5)
* Sacral: 5 (S1-S5)
* Coccygeal: 1
What are the 2 roots that connect the spinal nerve to the spinal cord and their function?
Ventral root (front): Carries motor fibres (axons) from the spinal cord to the muscles, allowing movement.
Dorsal root (back): Carries sensory fibres from the body to the spinal cord (touch, pain, temperature, etc.).
what are the contents of the dorsal root ganglion
The dorsal root ganglion contains mostly neuron cell bodies of sensory nerve fibres.
what are the levels that the spinal nerves exit from
- The C1-7 cervical nerves exit above their respective vertebrae
- C8 nerve exits below C7 vertebrae
- T1 and below exit below their respective vertebrae
- The lower the nerve root, the more it descends before exiting
what are long tracts
Long tracts are the axons passing from the brain to the spinal cord, and vice versa
what are the long tracts
Corticobulbar
Corticospinal
Medial Lemniscus
Anterolateral System
what is the function of the Corticobulbar long tract
Motor innervation to cranial nerves in brainstem
what is the function of the corticospinal long tract
Voluntary motor function
what is the function of the medial lemniscus long tract
transports messages for light touch and vibration from body
what is the function of the anterolateral system long tract
carries messages of pain and temperature from body
Can I name and locate the position of the sections of the brainstem?
Medulla oblongata – most caudal (bottom)
* Contains cranial nerves parts of 8, 9-12
Pons – middle section
* Contains cranial nerves 5-8
Mesencephalon/Midbrain – most rostral (top)
* Contains cranial nerves 3 & 4
Can I name the two structures making up the Diencephalon and its location?
Located at the top of the brainstem
Thalamus
Hypothalamus and pituitary
function of the brainstem
- Controls vital functions (breathing, HR)
- Origin of most cranial nerves
- Eye movements
- Passage for long tracts
function of the thalamus
Relay centre of the brain
function of the hypothalamus
Contains the anterior hypothalamus (parasympathetic) and the posterior hypothalamus (sympathetic).
Anterior hypothalamus:
* Rest and digest (relax) (parachute down)
* Slowing of heart
* Constriction of pupil
Posterior hypothalamus:
* Fight or flight response
* Increased heart rate and bp
* Pupillary dilation
function of the cerebellum
Attaches to the back of the brainstem
* Motor functions
* Coordination of movements
* Rhythm
* Timing
* Error correction
function of the basal ganglia
Inhibit and coordinates motor movement
Modulates activity of the cerebral cortex by regulating the thalamus
* Allows excitation, and/or
* Inhibits
Has involvement in:
* Motor function
* Learning
* Emotional processing
Can I briefly describe the arterial supply of the brain?
Supplied by the internal carotid and vertebral arteries
Vertebral arteries supply the brainstem, underside of the cerebrum, occipital cortex
Internal carotid supplies the remainder of the cerebrum and retinas
What is the circle of Willis
Formed by the joining of the anterior and posterior cerebral arteries
Arteries arising from here supply most of the brain
what are the 3 plexuses
cervical plexus
brachial plexus
lumbosacral plexus
what spinal levels does the cervical plexus originate from
Forms from the nerve roots of C1 to C5
function of cervical plexus
Function: Supplies many of the neck muscles, giving sensation over the back of the head, neck and supraclavicular. Gives rise to the phrenic nerve innervating the diaphragm.
what spinal levels does the brachial plexus originate from
Arises from C5 to T1
function of the brachial plexus
Function: Gives rise to the nerves (median, ulnar, radial) supplying the upper limb. Often involved in thoracic outlet syndromes and injury/trauma
what spinal levels does the lumbosacral plexus originate from
Arises from L1 to S5
function of the lumbosacral plexus
Function: Gives rise to the nerves supplying the lower limb. Often involved in clinical presentations in chiropractic practice
Describe the CNS
- The brain and the spinal cord
Describe the PNS
- Those parts of the nervous system outside of the brain and the spinal cord
Where does the spinal cord begin?
foramen magnum
What are the meninges function?
Their function is to:
* Protects the brain
* Structural support
* Helps with circulation of ventricle and cerebrospinal fluid (CSF)
Describe the layers of the meninges surrounding the spinal cord and brain
Dura mater - outer
Arachnoid mater - middle
Pia mater – inner
The dura mater continues as the Epineurium
Regarding the anterior and posterior hypothalamus, what would occur in healthy function?
In healthy function the anterior should regulate/inhibit the posterior
What are the components of the axon?
- Axon hillock (beginning)
- Axon proper (middle)
- Axon terminal (end)
Describe the inside of the cell and outside of the cell contents
- The inside of the cell contains more potassium (K+)
- The outside fluid contains more sodium (Na+) and chloride (Cl-)
- More Na+ is pumped out than K+ pumped in
- Results in a negative charge inside the cell
What is an action potential and how is it produced
- The action potential is the signal that travels down the axon causing the release of the neurotransmitters
- Produced by allowing Na+ ions to rush into the neuron, and K+ ions to rush out
What mV is an action potential triggered
-55mV
Describe the myelin sheath
- “Insulating layer” around an axon
- Increases speed of the wave of depolarisation down the axon membrane towards the axon terminal
Describe the nodes of Ranvier
- Gaps between myelin wrapped around the axon
- Allows an electrical impulse to “skip” from node to node down the full length of an axon. Thus, speeds the arrival of the impulse at the nerve terminal
What part of a neuron receives signals
Dendrites
Where are neurotransmitters released
Synaptic cleft
Myelin increases conduction speed (T or F)
True
What is the resting membrane potential
-70mV
What is the role of the anterolateral system
Carries messages of pain and temperature
Which ion is more concentrated outside the cell
Sodium na+
What happens at +30mv in an action potential
K+ channels open
Which is the most common excitatory neurotransmitter
Glutamate
Which neurotransmitter is important for memory
Acetylcholine
Which neurotransmitter is a peptide
Endorphins
Which ion is more concentrated inside the cell
Potassium
Which neurotransmitter is inhibitory in the brain
GABA
Ligand gated channels open with binding molecules (T or F)
True
What happens to the cell during depolarisation
Na+ rushes in
Which neurotransmitter is used by 75% of autonomic neurones
Acetylcholine
Which lobe of the brain is involved in decision making
Frontal
The spinal cord ends where
L1/2
What does the internal capsule contain
Axons
Which plexus supplies the upper limb
Brachial plexus
What does the dorsal root contain
Sensory fibres
The anterior hypothalamus is associated with….
Parasympathetics
