ANATOMY - Nervous System Cellular Anatomy Flashcards
What are the three main cell types found in the nervous system?
Neurones
Neuroglia
Ependymal
What are the three types of neuroglial cells?
Oligodendrocytes
Astrocytes
Microglia
What are the three structural classifications of neurones?
Multipolar
Bipolar
Unipolar
What is the main neurone structure involved in transmitting motor information?
Multipolar
What is the main neurone structure involved in olfaction?
Bipolar
What is the main neurone structure involved in transmitting sensory information?
Unipolar
What is a simple neurone communication circuit?
An individual presynaptic neurone stimulates another individual postsynaptic neurone
What is a divergent neurone communication circuit?
One neurone stimulates several neurones
What is a convergent neurone communication circuit?
Several neurones stimulates one neurone
What is a reverberating neurone communication circuit?
Neurone stimulation acts as a continuous feedback loop
Describe the process of neurone communication using neurotransmitters
- Action potential reaches the pre-synaptic axon terminal and triggers an influx of Ca2+ through opening voltage-gated Ca+ channels
- Ca2+ induced changes stimulate the synaptic vesicles to fuse with the pre-synaptic membrane and release neurotransmitters into the synaptic cleft
- Neurotransmitter bind to specific receptors on the post-synaptic membrane, triggering either an EPSP or IPSP
- Eventually the post-synaptic membrane will reach threshold and trigger an action potential
What is an excitatory post-synaptic potential (EPSP)?
Depolarisation of the post-synaptic cell, bringing the membrane potential closer to threshold and triggering an action potential
What is an inhibitory post-synaptic potential (EPSP)?
Hyperpolarisation of the post-synaptic cell, bringing the membrane potential further from threshold and thus further from triggering an action potential
What is the function of the myelin sheath?
The myelin sheath acts as an ‘insulator’ for some axons to minimise the dissipation of the electrical signal that is travelling along the axon, speeding up action potential transmission
What are the Nodes of Ranvier?
The periodic gaps between the myelin sheath where action potentials are triggered along a myelinated axon
What are the two classifications of neurotransmitter receptors?
Ionotropic
Metabotropic
What are ionotropic receptors?
Ligand gated ion channels
What are metabotropic receptors?
G-protein coupled receptors
What are the three ways neurotransmitters can be removed from the synaptic cleft?
Diffusion
Enzymatic breakdown
Reabsorption
Why is it functionally important that neurotransmitters can be removed from the synaptic cleft?
To prevent constant stimulation of the post-synaptic cell and excessive firing of action potentials
What are the three main excitatory neurotransmitters?
Glutamate
Aspartate
Nitric oxide
What are the main functions that glutamate neurotransmitters are involved in?
Cognition and emotion
How is glutamate removed from the synaptic cleft?
Astrocytes remove glutamate via excitatory amino acid (EAA) transporters
What are the four main inhibitory neurotransmitters?
Glycine
GABA
Serotonine
Dopamine
Which two neurotransmitters are both excitatory and inhibitory?
Acetylcholine
Noradrenaline
Which neuroglia cell type has a role in the blood brain barrier (BBB)?
Astrocytes
What is the main function of oligodendrocytes?
Myelinate axons in the central nervous system
What is the main function of microglia cells?
Microglia are resident immune cells
What is contained with the grey matter of the brain?
Neuronal cell bodies and dendrites
Astrocytes
What is contained within the white matter of the brain?
Myelinated axons
Oligodendrocytes
Microglia
What is contained within the white matter of the spinal cord?
Myelinated axons
What is contained within the grey matter of the spinal cord?
Neuronal cell bodies and dendrites
Which stain can be used to differentiate between grey and white matter in histology?
Luxol fast blue stain
Describe briefly the organisation of the peripheral nerves
Peripheral nerves are organised in bundles surrounded by the endoneurium, perineurium and epineurium
Which cell type myelinates axons in the peripheral nervous system (PNS)?
Schwann cells
What are the two main components of the central nervous system (CNS) microenvironment?
Blood brain barrier (BBB)
Blood cerebrospinal fluid (CSF) barrier
What are the four functions of the cerebrospinal fluid (CSF)?
Protection from trauma
Modulates pressure changes within the skull
Nutrition
Chemical buffer
Where is the cerebrospinal fluid (CSF) located within the central nervous system?
Ventricular system
Sub-arachnoid space
Spinal central canal
What are the two main components of the blood cerebrospinal fluid (CSF) barrier?
Choroid plexus
Ependymal cells
What is the choroid plexus?
Blind ending fenestrated capillaries with a continuous lining of ependymal cells
What is the function of the choroid plexus?
Produces cerebrospinal fluid
What is the function of ependymal cells?
Ependymal have tight junctions which act to filter blood to produce cerebrospinal fluid (CSF) as well as have cilia which are involved in regulating the movement and turnover of cerebrospinal fluid (CSF).
What mediates cerebrospinal fluid (CSF) flow through the central nervous system?
Blood pulsations and cilia of the ependymal cells
Describe the pattern of cerebrospinal fluid (CSF) flow through the central nervous system
Cerebrospinal fluid flows from the lateral ventricles through the interventricular foramina into the third ventricle, through the mesencephalic aqueduct to the fourth ventricle and through the lateral apertures into the sub-arachnoid space and central spinal canal
How is cerebrospinal fluid (CSF) reabsorbed into the bloodstream?
Cerebrospinal fluid (CSF) is resorbed by arachnoid villi that have petruded from the arachnoid mater, through and dura, and into the venous sinuses and back into the bloodstream via a pressure-dependent gradient
What is the main indicator for cerebrospinal fluid (CSF) collection?
Inflammation
(T/F) Small animals have to be anaesthetised for cerebrospinal fluid (CSF) collection
TRUE.
What are the landmarks for cerebrospinal fluid (CSF) collection at the cisterna magna?
Occipital protuberance
Wings of the altas (C1)
At which vertebrae can cerebrospinal fluid (CSF) be collected in dogs?
L5-L6
At which vertebrae can cerebrospinal fluid (CSF) be collected in cats?
L6-L7
At which vertebrae can cerebrospinal fluid (CSF) be collected in cattle and horses?
L6-S1
