T1 L5: Neural tissues Flashcards
Which embryological layer is the nervous system derived from?
The ectoderm
What are afferent neurones?
Transmit information to the CNS
What are efferent neurones?
They’re motor neurones transmitting information from the CNS to the effector organs
Where is the nucleus of a parasympathetic ganglion?
In the periphery. They’re also small
Where is the nucleus of a sensory ganglion?
In the centre. They’re large
What are Brodmann’s areas?
Numeric descriptions of areas of the brain
What is found in Broadmann’s area 4?
The primary motor cortex
What is found in Brodmann’s area 17?
The primary visual cortex
What is the difference between the different Brodmann’s areas?
They each have a different input and output as well as function
Where are pyramidal neurones found?
In the cerebral cortex
Where are Purkinji neurones found?
In the cerebellar cortex
Where are pseudounipolar neurones found?
In the dorsal root ganglia. They are sensory neurones
What are the characteristics of a bipolar neurone?
1 dendrite and 1 axon
What are the characteristics of a pseudounipolar neurone?
1 axon and 1 dendrite but the axon is sticking out on the side of the neurone
How big is the synaptic gap between chemical synapses?
~ 30nm
What is a divergent neurone?
A single neurone that sends output signals to many neurones
What is a convergent neurone?
Multiple inputs influence a single neurone
Where do interneurons occur?
Only in the CNS
What structures are the most common causes of tumours in the NS?
Glia
What is Glia
Cells that support neurones
What are some characteristics of Glia?
They have no action potentials
Don’t form synapse
Are able to divide
They form the myelin sheath
What is the function of Oligodendorcytes?
They produce and maintain the myelin sheath in the CNS. One Oligodendrocyte can myelinate multiple axons on different neurones
What is the function of Astrocytes?
They are star-shaped cells that assist neuronal growth/development (are neurotrophic).
They protect neurones from harmful substances
They also influence the blood-brain barrier and blood flow
What is the function of microglia?
They are immune cells that protect cells from disease, migrate to sites of injury, engulf microbes and debris.
What embryological layer do microglia originate from?
From the mesoderm like other immune cells. They are also able to develop from monocytes
What is the function of ependymal cells?
They line the brain’s ventricles and the central canal of the spinal cord
What cells of the CNS work with cilia and microvilli?
Ependymal cells. They basically create a sort of epithelium
What is the function of Schwann cells?
They are only found in the PNS. They produce and maintain the myelin sheath.
A single Schwann cell can only associate with a single axon
What is the function of satellite cells?
They are only found in the PNS (muscles).
They regulate exchange of materials between neurones and interstitial fluid
What is a glioma?
A type of tumour that originates from glial cells. They are usually highly malignant and grow rapidly. Very difficult to remove completely with surgery. Usually form within the cranium
What is a neuroblastoma?
A cancerous tumour most common in children and infants (during development when the levels of Catecholamine are increased). Occurs outside the cranium.
Survivors often develop neurological problems ~ 30 years later.
Treatment and prognosis depends of the type.
