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BIOL1040 EXAM REVISION > Module 2: Nervous System > Flashcards

Module 2: Nervous System Flashcards

1
Q

Draw a labelled diagram showing the stages of an Action Potential:

A

See booklet for correct diagram

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2
Q

Outline 5 points with regards to Membrane Potential:

A
  1. The resting membrane potential is negative because Na+/K- ATP-ase pumps 3Na+ out and 2K in
  2. The membrane at rest has many open K+ channels and few Na+ or Cl-
  3. This has nothing to do with voltage gated ion channels! Those are for action potentials
  4. There is a build-up of negative charge in the neutron
  5. Equilibrium is approx. -70mV in the human neuron. All cells have a membrane potential
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3
Q

Describe the 6 steps of the structure-function of membrane channels: Sodium-Potassium pumps:

A
  1. The interior of the pump is open to the inside of the axon; 3 sodium ions enter the pump and attach to their binding sites
  2. ATP transfers a phosphate group from itself to the pump, causing the pump to change shape and the interior is then closed
  3. The interior of the pump opens to the outside of the axon and three sodium ions are released
  4. Two potassium ions from outside can then enter and attach to their binding sites
  5. Binding of potassium causes release of the phosphate group, causing the pump to change shape so it is only open to the inside of the axon
  6. Sodium ions can then enter and bind to the pump
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4
Q

Describe the 3 steps of the structure-function of membrane channels: Voltage-gated sodium channels:

A
  1. Channel is closed. There is a negative charge inside the axon and a net positive charge outside. The channel is voltage gated
  2. If the net charge is negative on the outside, the protein moves so that it is open temporarily
  3. A ‘ball’ fits into the pore within milliseconds of the pore opening, which is removed when the channel returns to its original closed state
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5
Q

Give an example of a use for the Voltage-gated sodium channel:

A

Local anaesthetics

- act on the ‘ball’ of the ‘ball and chain’ mechanism, causing the channel to be inactivated longer

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6
Q

List and describe the 3 factors affecting conduction:

A
  1. Myelination: Insulation of myelin sheath allows for saltatory conduction (‘skipping’ along the nodes of Ranvier) for faster conduction
  2. Axon diameter: Less resistance of the action potential allows it to propagate faster, not as a effective as myelination
  3. Temperature: faster activity
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7
Q

List the 3 steps of information processing in nervous systems:

A
  1. Sensory output
  2. Integration
  3. Motor output
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8
Q

List everything in the structure of a neuron (10)

A
  1. Presynaptic cell
  2. Synapse
  3. Postsynaptic cell
  4. Nucleus
  5. Cell body
  6. Dendrites
  7. Axon hillock
  8. Axon: myelin sheath, Schwann cells, Nodes of Ranvier
  9. Synaptic terminals
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9
Q

List and describe the 3 types of Neurons:

A
  1. Sensory neurons: have the cell body in the middle of the axon
  2. Interneurons: have very branched dendrites with a lot of exposure, but not as branched axon terminals
  3. Motor neurons: look more ‘classic’, with branched dendrites but not as branched axon terminals, and very long axon
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10
Q

Describe the main components of nerves:

A
  • a nerve consists of many neurons, connective tissues and blood vessels
  • glial cells are vital for structural integrity and normal functioning for the neurons
  • there are 10-50 times more glia than neurons in the mammalian brain
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11
Q

List and describe the types of glial cells: Those that form myelin sheaths (lipid sheaths) that insulate the axon:

A
  • Oligodendrocytes: of the CNS

- Schwann Cells: of the PNS

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12
Q

Describe the features of Astrocytes (a glial cell) of the CNS:

A
  • used for structural support
  • regulates extracellular concentration of ions and neurotransmitters
  • formation of the blood brain barrier
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13
Q

Describe the formation of the Blood-brain barrier

A
  • astrocyte foot processes
  • basement membrane
  • tight junctions (no toxins allowed through)
  • endothelial cell
  • only diffusion through astrocytes and endothelial cells are allowed through the blood vessels
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14
Q

Describe the structure of synapses and synaptic transmission

A
  • synapses are very close to each other and form tight junctions
  • this close proximity prevents fluid moving across a layer of cells
  • gap junctions are where neurotransmission occurs
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15
Q

List and describe the 2 types of Postsynaptic potential types:

A
  1. EPSP: excitatory postsynaptic potential: occurs if depolarisation at postsynaptic membrane
    - temporal summation: several EPSP’s can reach the threshold at the axon hillock, causing an action potential
    - spatial summation: two or more EPSP’s from different synapses: the closer synapse will produce the fastest response
  2. IPSP: inhibitory postsynaptic potential: if hyper polarisation at postsynaptic membrane
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16
Q

List the 4 types of Summation

A
  1. Sub-threshold (no summation)
    - E1 and E1 one after another, does not reach threshold potential
  2. Temporal summation
    - E1 and E1 close enough after another, reaches threshold potential
  3. Spatial summation of EPSPs
    - E1 and E2 together reaches threshold potential
  4. Spatial summation of EPSP and IPSP
    - E1 depolarises, I hyperpolarises, E1 and I together small depolarisation, does not reach threshold potential
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17
Q

List/ draw the process of Synaptic Neurotransmission (9 steps)

A
  1. Nerve impulse is propagated along the pre-synaptic neuron until it reaches the pre-synaptic membrane
  2. Depolarisation causes Ca ions to diffuse through channels in the membrane
  3. This causes vesicles containing neurotransmitter to fuse with the membrane
  4. Neurotransmitter is realised into the synaptic cleft via exocytosis
  5. Neurotransmitters diffuse and bind to receptors on the post-synaptic membrane
  6. Binding of neurotransmitter to receptor open Na ion channels
  7. Na ions diffuses down the concentration gradient into the post-synaptic membrane, causing it to reach threshold potential, -50mV
  8. An action potential is triggered in the post-synaptic membrane and propagated along
  9. Neurotransmitter is broken down
18
Q

List and give the action of the 4 types of Post-synaptic potentials

A
  1. EPSP or IPSP: only depolarisation
  2. Graded: all or nothing
  3. Local: EPSPs add up to cause action potential
  4. At cell body or dendrites: Generated at axon hillock, travels along axon
19
Q

Describe Direct synaptic transmission

A
  • neurotransmitter opens ion channels on post-synaptic membrane
  • leads to a graded post-synaptic potential
  • ligand-grated ion channels: ion channel linked receptors (fastest)
20
Q

Describe Indirect synaptic transmission

A
  • neurotransmitter binds to post-synaptic membrane receptor
  • activates signal transduction pathway involving a second messenger: G-protein coupled receptors (slower)
  • can result in EPSPs or IPSPs depending on neurotransmitter and receptor type
21
Q

List the 4 types of Amino Acid Neurotransmitters

A
  1. GABA (gamma aminobutyric acid)
  2. Glycine
  3. Glutamate
  4. Aspartate
22
Q

List the 4 types of Amine Neurotransmitters

A
  1. Acetylcholine
  2. Noradrenaline
  3. Dopamine
  4. Serotonin/ 5HT
23
Q

List the removal of neurotransmitters from the synaptic cleft in order of likelihood

A
  1. Recycled by selective uptake by transporters (e.g. NET, SERT)
  2. Taken up by astrocytes
  3. Broken down by enzymes (e.g. acetylcholinesterase)
  4. Diffusion: least likely due to small gap junctions
24
Q

List and give examples of the Organisation of a circuit for primitive organisms: (3)

A
  1. Cnidarians (e.g. hydra)- nerve net
  2. Echinoderms (sea stars)- radial nerves from nerve rings
  3. Flatworms (planarians)- eyespot, brain, nerve cords with traverse nerves
25
Q

Give examples (2) of more complex invertebrate nervous system:

A
  • segmentally arranged clusters of neurons into a ganglia- PNS, connected to a central nervous system
    1. Annelids (leeches)- brain, ventral nerve cords, segmental ganglion
    2. Arthropods (insects)- brain, ventral nerve cords, segmental ganglia
26
Q

Give examples (2) of diverse nervous systems based on lifestyle (e.g. molluscs)

A
  • mollusc organisation depends on lifestyle
    1. Mollusc (chitin)- ganglia, anterior nerve ring, longitudinal nerve cords
    2. Mollusc (squid)- brain, ganglia
  • -> the giant axon of the squid is used as an experimental model in physiology
27
Q

Explain the most complex vertebrate nervous systems

A
  • Consists of central nervous system, peripheral nervous systems, regional specialisation
    1. CNA- brain and spinal cord
    2. PNS- spinal nerves branching outwards, cranial nerves containing sensory and motor neurons
28
Q

List the 7 stages of the Reflex Arc:

A
  1. Skin/muscle
  2. Sensory neurons
  3. Dorsal root ganglion on sensory neuron
  4. Interneuron at spinal cord
  5. Motor neuron
  6. Ventral root on motor neuron
  7. Muscle
29
Q

List the divisions of the PNS

A

PNS –> Somatic nervous system (voluntary action) or Automatic nervous system —> Sympathetic division (fight or flight) or Parasympathetic division (rest and digest) or Enteric division (gastrointestinal functions)

30
Q

List 4 components of the Cerebrospinal fluid

A
  • subarachnoid space
  • 4 ventricles and central canal
  • supply of nutrients and hormones, removes waste
  • in hydrocephalus, the flow is blocked (skull swells)
31
Q

List the 4 different components of the Brain

A
  1. Grey matter
  2. White matter
  3. Ventricles
  4. Spinal cord
32
Q

List 3 components of Grey matter:

A
  • dendrites
  • unmyelinated axons
  • cell bodies
33
Q

List 1 component of White matter:

A
  • myelinated axons in tracts
34
Q

List 1 component of ventricles:

A
  • network of cavities that transports cerebrospinal fluid
35
Q

List 3 components of Spinal cord:

A
  • grey matter
  • white matter
  • butterfly appearance
36
Q

What are the 7 regions of the brain:

A
  1. Frontal lobe
  2. Parietal lobe
  3. Occipital lobe
  4. Diencephalon
  5. Brainstem
  6. Cerebellum
  7. Temporal lobe
37
Q

Breakdown/describe the Cerebrum (forebrain) components (4 parts)

A
  1. Frontal lobe:
    - prefrontal cortex: decision making and planning
    - motor cortex: control of skeletal muscle
    - Broca’s area: speech formation
  2. Temporal lobe:
    - auditory cortex
    - Wernicke’s area: comprehension of language
  3. Parietal lobe:
    - somatosensory cortex: touch
    - sensory association cortex: integration
  4. Occipital lobe:
    - visual association cortex: object recognition
    - visual cortex: processing and pattern recognition
38
Q

Breakdown/describe the Midbrain components (1 part)

A
  1. Brain stem:
    - evolutionarily old
    - basic functions
    - homeostasis, movement
    - transfers information
    - sections: pons, midbrain, reticular formation (selectivity filter determines arousal and sleep), medulla oblongata
39
Q

Breakdown /describe the Hindbrain components (1 part)

A
  • some of brain stem
    1. Cerebellum
  • coordination
  • motor function
  • cognitive and perceptual functions
40
Q

Breakdown/describe the Diencephalon (forebrain) components (3 parts)

A
  1. Epithalamus
    - connects limbic system (emotions) to rest of brain
    - pineal gland secretes melatonin (sleep)
  2. Thalamus
    - input from sensory neurons
    - output via motor neurons
  3. Hypothalamus
    - homeostatic regulation via hormones
    - circadian rhythms
    - survival

BIOL1040 EXAM REVISION (7 decks)

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