Test 3 Flashcards
Four parts of the neurone and their function?
Dendrites:
- Processes on the cell that receives a connection from other neurones.
Cell body (soma):
- Where the nucleus and most organelles of the cel 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.
Can I describe the phases of the action potential?
- Membrane potential hits -55 mv
- Voltage gated Na+ channels open
- Na+ rushes into the cell
- Membrane is depolarised
- Membrane potential reaches +40mV
- Voltage gated Na+ channels close
- At +30mV voltage gated K+ channels open,
- K+ rush in to restore the membrane
charge - Repolarisation
- K+ rush in to restore the membrane
- Pushes into hyperpolarisation
- K+ equilibrium is closer to -90mV
- Neurone can’t be fired during this “refractory period”
- Whole process takes about 2 milliseconds
The different channel types and how they function:
Energy Dependent:
- Some channels depend on energy to move ions through them
- Sodium/potassium pumps are one example
Charge Dependent:
- Only allow certain charged ions through.
- Sides may have a positive charge, so will repel positive ions but attract negative ions.
Size Dependent:
- Only allow ions of a certain size through
- Diameter of the channel may match the diameter of the ion in question.
Ligand Gated Channels:
- Only open for certain events.
- Only open when a certain molecule binds to part of the channel.
Mechanically Gated Channels:
- Open with the distortion of the cell membrane.
- Common with touch receptors
- Temperature may have a similar effect.
Voltage Gated:
- Open with changes in the electrical charge on the membrane.
- Na+ channels open when membrane hits -55mV
Leakage:
- Randomly open and close
- Due to intrinsic switching
- Leaking ions
Name the neurotransmitters belonging to each of the groups:
Amino Acids:
- GABA
- Glutamate
- Glycine
Peptide:
- Opioids such as endorphins
Monoamines:
- Serotonin
- Histamine
- Adrenaline
- Nor-adrenaline
- Dopamine
Others:
- Acetylcholine
Basic roles of neurotransmitter groups:
Amino Acid:
- Glutamate excitatory neurotransmitter
- GABA inhibitory neurotransmitter in the brain
- Glycine inhibitory neurotransmitter in the spinal cord
Peptide:
- Pain modulation
Monoamine:
- Acrivation of the brain, emotion, consciousness and attention.
Other:
- Memory and brain activation
The function of the 4 lobes of the brain
Frontal:
- Motor
- Decision making
- Motivation
- Social decisions
Occipital:
- Vision
Temporal:
- Hearing
- Speech comprehension
- Emotion
- Memory
Parietal:
- Somatosensory (body sensation)
- Integration of sensation
- Spatial awareness
- Reading, speech comprehension
Borders that separate the lobes:
Frontal:
- Divided from the temporal by Slyvian fissure
- Divided from the parietal lobe by the central sulcus.
Parietal:
- Divided from temporal and occipital lobes by the large Sylvian Fissure and arbitrary boundaries.
- Divided from the frontal lobe by the central sulcus.
Occipital Lobe:
- Divided by temporal and parietal lobes by arbitrary boundaries.
Temporal Lobe:
- Divided from the frontal, parietal and occipital lobes by the large Sylvian Fissure and arbitrary boundaries.
Differences between grey and white matter:
Grey matter:
- More cell bodies
White matter:
- More axons
What levels do spinal nerves exit from?
- C1-7 exit above their respective vertebrae.
- C8 nerve exits below C7 vertebrae.
- T1 and below exit below their respective vertebrae.
What is the difference between ventral and dorsal roots?
- Ventral roots contain more motor fibres (axons)
- Dorsal roots contain sensory fibres.
Describe the basic function of the long tracts:
Corticobulbar:
- Motor innervation to cranial nerves.
Corticospinal:
- Voluntary motor function.
Medial Lemniscus:
- Transports messages for light, touch and vibration from body.
Anterolateral System:
- Carries messages of pain and temperature from the body.
Name and locate the position of the sections of the brainstem:
Medulla:
- Most caudal (bottom)
- CN (8), 9-12
Pons:
- Middle section
- CN 5-8
Mesencephalon/Midbrain:
- Most rostral (top)
- CN 3 & 4
General Function of the brainstem:
- Origin of most cranial nerves
- Eye movements
- Vital functions
- Passage for long tracts
General function of the thalamus:
- Relay centre of the brain.
- High level of connectivity to many regions of the brain.
- Relay station for cortical input
- Regulation of cortical function
General function of the hypothalamus
- Anterior hypothalamus is parasympathetic
- Rest and relax
- Slowing of heart
- Constriction of pupil
- Salivation
- Intestinal peristalsis
- Posterior hypothalamus is sympathetic
- Fight or flight response
- Increased heart rate
- Increase blood pressure
- Pupillary dilation
- Intestinal stasis
General function of the cerebellum
Motor functions:
- Coordination of movements (rhythm, timing and error correction)
General function of the basal ganglia:
- Modulates activity of the cerebral cortex by regulating the thalamus
*Allows excitation, and/or inhibits - Has involvement in:
- Motor function
- Learning
- Emotional processing
Briefly describe the arterial supply to 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
The 3 plexus’ and the spinal levels they originate from:
Cervical Plexus:
- C1-C5
- Neck muscles
- Sensation over the back of head, neck and supraclavicular.
Brachial Plexus:
- C5-T1
- Nerves supplying the upper limb (median, ulnar, radial)
- Often involved in thoracic outlet syndromes.
Lumbosacral Plexus:
- L1-S5
- Lower limb
Name the structure that make up the Diencephalon:
Thalamus:
– Relays information to the cortex
Hypothalamus and pituitary:
- Part of the limbic system (emotional brain), hormone regulation, homeostasis
What is the main function of neurones?
- Filter blood
- Produce hormones
- Transmit signals
- Store energy
Transmit Signals
Which part of a neurone receives signals?
- Axon
- Soma
- Synapse
- Dendrites
Dendrites
