Neural Tissues Practise Questions 2023-10-10 - Tagged.pdf

Neural Tissues Practise Questions Comments or suggestions? Contact: Dr. Harry Witchel [email protected] Core memorisation What is the difference between the central nervous system and the peripheral nervous system? • CNS is the brain & spinal cord; PNS is all else. CNS is associated with Cer...

Neural Tissues Practise Questions Comments or suggestions? Contact: Dr. Harry Witchel [email protected] Core memorisation What is the difference between the central nervous system and the peripheral nervous system? • CNS is the brain & spinal cord; PNS is all else. CNS is associated with Cerebrospinal fluid. CNS Click toof seeglial answercells (eg has a different cohort oligodendrocytes vs Schwann cells) Which embryonic layer/tissue is the nervous system derived from? • Ectoderm (or neuroectoderm) Click to see answer What are the main functions of neuroglia? • Protect, nourish, support • Make myelin (and increase conduction velocity) Click to see answer • Regulate fluid and ion transport across membranes What is a Node of Ranvier? • On an axon, this is a segment of an axon that is not covered with myelin, but is bare and facing the extracellular fluid • It is an excitable part of the axon (whereas to see answer membrane underClick myelin is not excitable) – Na+ channels are clustered at nodes • This is where action potentials occur, and it is fundamental in saltatory conduction What is myelin? • Myelin is a protective substance surrounding axons that is made up of successive layers of plasma membrane. As such, it is mostly lipid bilayers. Click to see answer • It works as an electrical insulator • It increases transmembrane resistance and decreases transmembrane capacitance What is the purpose of myelin? • By reducing transmembrance conductance, myelin can lead to saltatory conduction Click to see answer • Thus myelin increases conduction velocity. • This means axons can have a thinner diameter and retain their conduction velocity What histological and physiological traits distinguish a neuron? • Neurites (outgrowths) • Excitability (can have action potentials) Click to see answer • Many neurons have quite large cell bodies What histological traits distinguish an astrocyte? • Many processes – Star shaped to see answer • Its feet abut bloodClick vessels What histological traits distinguish a microglial cell? • Small compared to other glia • Spindly processes Click to see answer What histological traits distinguish an ependymal cell? • Adjacent to a Site of CSF • Organised as an epithelial layer – I.e. highly cellular Click to see answer – cilia What histological traits distinguish an oligodendrocyte? • Can surround multiple axons Click to see answer What histological traits distinguish a Schwann cell? • Wrapped around an axon • Only around a single axon Click to see answer • Peripheral nervous system only What histological traits distinguish a satellite cell in the peripheral nervous system? • Small and round • Located as a group around a neuron’s large Click to see answer soma • Often shown in Dorsal Root ganglia What is the function of a neuron? • It communicates information quickly (allowing organism to respond to the environment) Clickaxon to see answer • It does this by firing potentials • In networks, it integrates information What is the function of an astrocyte? • Support of nervous tissue • Contributes to blood vessel control in CNS – Perfusion, possibly Click to see answer permeability • May be involved in the blood brain barrier • Repair of nervous tissue after trauma What is the function of a microglial cell? • Immune defense in the CNS – – – – Protect nervous tissue Click to see answer CNS is immune-privileged due to blood brain barrier Antibodies from rest of body are not in CNS CNS cannot tolerate inflammation What is the function of an ependymal cell? • Forms CSF – Controls fluid and ion transport Click tothat see answer • Forms the epithelium lines ventricular system What is the function of an oligodendrocyte? • Forms myelin in CNS – Increase conduction velocity – Insulates axons Click to see answer – Increases transmembrane resistance & decreases capacitance What is the function of a Schwann cell? • Makes myelin in the peripheral nervous system – Increases conduction velocity – Insulates axons Click to see answer – Increases transmembrane resistance & decreases capacitance What is the function of a satellite cell in the peripheral nervous system? • In PNS, these support neurons – Control microenvironment Click to see answer – Similar roles to astrocytes • Protect and cushion neurons Name a cell type or place where you would find a multipolar neuron. • Many possible answers, including • Cerebral cortex – Pyramidal cells Click to see answer • Cerebellar cortex – Purkinje neurons Name a cell type or place where you would find a bipolar neuron. • Many possible answers, including • Retina – Bipolar cells Click to see answer • ganglia of the vestibulocochlear nerve – Bipolar cells Name a cell type or place where you would find a pseudounipolar neuron. • Best example is dorsal root ganglia to see answer • Also in semilunarClick ganglia of trigeminal nerve What location on the brain does this arrow point to? Click to see answer • Dorsomedial prefrontal cortex What location on the brain does this arrow point to? Click to see answer • Ventrolateral prefrontal cortex • This is near, but not exactly at, Broca’s area Conceptual Name a place where you would find afferent neurons. • • • • Many examples including sensory neurons from Special senses (retinal ganglia, cochlea, etc) Click to see answer Sensory neurons (and pain receptors) from skin Proprioceptors from muscles Name a place where you would find efferent neurons • Many examples including motor outputs from brain Click to see answer • Motor cortex • Ventral horn of spinal cord What kind of axon fibres have the fastest conduction velocity? • Neurons that are myelinated • Neurons that have a large cross-sectional area Click to see answer • E.g. Alpha motor neurons Name 4 ways in which glia (in general) differ from neurons (in general). • • • • • • Neurons have action potentials, glia do not *E Glia do not form synapses Glia are able to divide, neurons cannot *E Click to see answer Glia form myelin sheaths Neurons are usually bigger *E There are many more glial cells than neurons Name 4 differences between a glioma and a neuroblastoma. • Glioma typically affects older individuals, neuroblastoma typically affects babies and very young individuals • Glioma is usually inside cranium, neuroblastoma is usually outside cranium Click to see answer • Glioma often has a poor outcome (malignant), neuroblastoma often has a good outcome • Neuroblastoma often secrete catecholamines, leading to high blood catecholamines Name two differences between an oligodendrocyte and a Schwann cell. • Oligodendrocyte is in CNS • Oligodendrocyte typically myelinates many Click to see answer neurons What kind of neurons (histologically) would you expect to find in the dorsal root ganglia? • Pseudounipolar Click to see answer Name two locations where you would expect to find ganglia in the peripheral nervous system. • Enteric nervous system – Auerbach’s and Meissner’s to see answer • Parasympathetic Click ganglia in glands • Sympathetic chain ganglia Approximately how many neurons are in the brain? • 1011 • 100 (American) billion Click to see answer Subtleties of conceptual information What is a Brodmann area? • A region of nervous tissue on the cerebral cortex – E.g. the primary visual cortex (V1) of the occipital cortex is Brodmann area 17 – E.g. the motor cortex issee Brodmann area 4 Click to answer • Each region is defined by its structure or organisation of cells Which part of the prefrontal cortex is nearest to the primary auditory cortex (on the outer shell of the temporal lobe): ventrolateral, ventromedial, dorsolateral, dorsomedial? • Ventrolateral prefrontal cortex is closest to the auditory cortex ofClick theto see temporal lobe answer