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M101 > W4 Divisions and function of the Nervous System > Flashcards

W4 Divisions and function of the Nervous System Flashcards

1
Q

What does the Central Nervous System (CNS) consist of?

A

Brain and spinal cord

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2
Q

What does the Peripheral Nervous system consist of?

A

Afferent nerves and Efferent nerves
Divided into somatic and autonomic

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3
Q

A target effector organ, such as the heart, receives input from the sympathetic
and parasympathetic systems. What are the actual anatomical difference between the
sympathetic and parasympathetic divisions at the level of these synapses. What affects do these systems have on the heart (4 marks)?

A

Parasympathetic:
Neurones in this system release Ach on their effector organ. This binds to the Muscarinic receptor and decreases hart rate

Sympathetic:
Neurones in this system release Noradrenaline on their target organ and bind to an adrenergic receptor on their target organ. This system
increases heart rate/force.

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4
Q

What are the different building blocks of the nervous system?

A
  • Neurones
  • Oligodendrocytes (CNS)/Schwann
    cells (PNS)
  • Microglia
  • Astrocytes
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5
Q

What are the function of
1. Oligodrendrocytes (CNS)/Schwann cells (PNS)
2. Microglia?

A
  • Produce myelin, facilitate transmission
  • Immune cells of the brain
  • Phagocytose dead cells and debris
    Most of the brain is glial cells
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6
Q

What is the function of Neurones?

A
  • Many have a lipid sheath called myelin
  • Responsible for communication (Action
    potential / neurotransmission)
  • Neurones are highly specialised cells
  • Transmit information as electrical signals (nerve impulses or action potentials)
  • Action potentials only travel one way – from dendrites to axons
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7
Q

What are the different features of a neurone?

A

Dendrites – receive information, start action potential
Soma (cell body)- Contains all the organelles you would expect! Also contains nucleus Axon – propagates action potential
Axon terminals – communicate with other neurones / muscles .
myelin sheath
nodes of ranvier

  • Axons originate at axonal hillock
  • Cell body: control centre
  • Cytoskeleton extends out from cell body through axon
  • Allows material to be transported from cell body to axon terminal (and back)
  • Where axon terminal meets target cell termed synapse
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8
Q

What are the 3 functional types of neurons?

A

PNS
1. Afferent or Sensory neurons (sense) –
* signals from the periphery to CNS
2. Efferent neurons
* Motor neurons (respond): signals from the CNS to the muscles/skin etc
* Autonomic neurons (respond): signals from CNS to smooth muscle/glands

  • CNS
    3. Inteneurons (intergrate) connecting brain and spinal cord

Unipolar, Biplolar, Multipolar (for info)

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9
Q

What is the function of Astrocytes?

A
  • Enable homeostasis, physical
    barrier/connector, buffer, reuptake of
    neurotransmitters support neurones
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10
Q

What is a nerve?

A

A collection/bundle of neurones.

Peripheral NS – sensory and motor (somatic and autonomic) peripheral nerves
* Inside are a number of fascicles containing the axons of a neuron
* CNS: Tracts = bundle of axons connecting nuclei

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11
Q

What is a synapse?
What triggers the release of neurotransmitter?
What happens in the synaptic cleft?

A
  • Where one neurone meets another – synapse
  • Electrical action potential triggers release of chemical signal (neurotransmitter)
  • Neurotransmitters from the presynapse bind to postsynaptic receptors, triggering
    depolarisation of the postsynaptic neurone
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12
Q

What is an excitatory vs inhibitory synapse?

A

Excitatory- Stimulus (AP) in the second neurone (depolarisation) +ve
Inhibitory- Stimulus in 1st makes an AP
less likely to occur in 2nd neurone (hyper polarisation) -ve

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13
Q

How are synapses complex structures?

A
  • Multiple synapses onto the same
    dendrite
  • Not just 2 neurons in series
  • Different synapses can be excitatory or
    inhibitory
  • Whether the neurone fires or not is a
    sum of all the synaptic inputs
  • Ie it sums up all of the positive and
    negative messages
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14
Q

What are 3 types of neurotransmitters?

A
  1. Excitatory e.g. glutamate, acetylcholine, monoamines e.g. dopamine, noradrenaline, 5HT/serotonin
  2. Inhibitory e.g. GABA
  3. Others-neuromodulators e.g. neuropeptides, endocannabinoids
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15
Q

What are they key excitatory neurotransmitters?

A

GLUTAMATE
acetylcholine
monoamines e.g. dopamine, noradrenaline, 5HT/serotonin

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16
Q

What are they key inhinbitory neurotransmitters?

A

– GABA
– Glycine
– Endorphins

17
Q

The response of which is faster?
Ligand gated ion channel or GCPR?

A

Ligand-gated as it is a channel through the membrane, it is the fastest type of response?

18
Q

What are the parts of the brain?

A

Cranium (protection)
Meninges (membranes)
CSF inbetween (cerebrospinal fluid)

19
Q

What is Cerebrospinal fluid (CSF)?
How does it provide protection?

A
  • Salty solution secreted into ventricles
    (chambers in the brain) by choroid
    plexus

Protection
* Physical: buoyancy and padding
* Chemical: Stable ionic environment.
* Different to plasma
* No blood cells little protein

20
Q

Blood supply to the brain (for info)

A
  • Nervous tissue: high metabolic requirements
  • Requires high rates O2 and glucose
  • 15 % of blood supply to brain
  • Very sensitive to Ischaemia (lack of O2)
  • Highly perfused/high capillary density
21
Q

How does the blood brain barrier (BBB)
protect the CNS?

A

Stops most immune cells from the blood from entering the brain and the CNS
Formed by endothelial cells

For info
* Capillaries in the brain less permeable: BBB
-Exclude many molecules entering from the bloodstream
* Protects brain from fluctuations in blood
* Endothelial cells line the capillary walls with tight
junctions between them
* Processes from glial cells astrocytes form a barrier
around blood vessels
* Some lipid soluble molecules can diffuse through cells
* Specific transporters allow certain molecules to access
the brain
* The BBB is not complete in some brain areas
Eg Pituitary
Vomiting centre in medulla

22
Q

CNS: The brain and spinal cord
What is grey matter and white matter?

A
  • Grey matter: Nerve cell bodies
  • Clusters called nuclei
  • White matter: axons
    -Bundles of axons that connect different regions called tracts
    -Often myelinated – lipid substance that covers some axons to speed up neurotransmission)
  • The spinal cord is where information comes into the CNS and directions are sent out
  • Messages are sent to and from the brain
  • Vertebral Column protects the spinal cord
23
Q

Spinal cord

A

Sensory nerve in
Motor nerve out (to muscles and
glands)
* Four regions: Cervical, Thoracic, Lumbar, Sacral
* Segments within these give rise to spinal nerves
* Distinct pattern (transverse /cross section)
* Sensory nerves enter via dorsal root
* Motor nerves leave via ventral root

  • White matter : number of columns
  • Consists of myelinated axons carrying information to and from the brain
  • Ascending tracts: Info to brain from periphery
  • Descending tracts: Info from the brain to periphery
24
Q

Spinal cord: Peripheral nerves (not CNS) (for info)

A

There are two main types; spinal nerves
and cranial nerves
* Peripheral nerves: (branches off from
spinal cord).
* Spinal nerve: a mixed spinal nerve, which
carries motor, sensory, between the spinal
cord and the body.
* Paired peripheral nerves that arise from
the spinal cord.
* In humans there are 31 pairs:
* 8 cervical,
* 12 thoracic,
* 5 lumbar,
* 5 sacral, and
* 1 coccygeal.
* Each pair connects the spinal cord with a
specific region of the body.

25
Q

CNS: Human Brain
What are the different components? (4)

A
  1. Brain stem: involuntary functions! blood pressure, breathing, vomiting, sleep/arousal
    * Midbrain
    * Pons
    * Medulla
  2. Cerebellum: co-ordinates movement
  3. Diencephalon: Homeostasis
    * Between brain stem and cerebrum!
    * Thalamus
    * Hypothalamus and pituitary
    * Pineal gland
  4. Cerebrum: Higher Functions
26
Q

What are the 4 regions of the cerebrum?
What are their functions?

A
  • 2 hemispheres joined by the corpus callosum
  • Surface folded
    1. Frontal: reasoning, planning, speech,
    movement, problem solving
    2. Parietal: movement/orientation
    recognition, stimuli perception
    3. Occipital: visual processing
    4. Temporal: perceptions/recognition of
    auditory stimuli
27
Q

Cerebrum: Sub cortical structures (for info)

A
  • Three clusters of nuclei (cell bodies)
  • Basal ganglia: Control of movement
  • Limbic system
  • Amygdala: emotion and memory
  • Hippocampus: Learning and memory
    (under temporal lobe)
28
Q

Which cranial nerve is important? (PNS)

A

The vagus nerve carries a lot of info to the body

M101 (41 decks)

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