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