General Flashcards
What types of glia are there?
Astrocytes - star-shaped cells, bridge between neuron + blood vessels
Ependymal cell - simple ciliated cuboidal cell lining ventricular system
Microglia - small glial cells, activated by trauma
Oligodendroglia - myelin producing cells CNS, form foot processes
Schwann cells - myelin producing cells PNS, whole cell wraps around
What can cause dysfunction of the nervous system?
Damage by trauma or disease
Neurons lose ability to produce transmitters
Neurons over- or under-produce transmitters
Neurons fail to recognise transmitters
Effector organs fails to respond
What is saltatory conduction?
Nodes of ranvier allow action potential to travel much faster as it can jump from node to node
What are differences between electrical and chemical synapses?
Chemical - Fast transmission (slower cell-cell, but can cope with Higher
Frequency of activity), Vesicles releases from presynaptic terminal, Act on receptors in postsynaptic terminal, Major drug target
Electrical - Slower transmission (faster cell-cell, but more effective at lower freqs), Gap junctions, Small molecules and current, low-pass filter (slow down transmission), Synchrony, Up-and-coming drug target
What are the main neurotransmitters used by the CNS?
Glutamate and GABA
What are 3 types of Inhibition responsible for coding of activity?
Direct inhibition
Lateral inhibition
Disinhibition
Describe coding of neuronal activity
Excitatory neurons have regular firing in absence of inhibition
Inhibitory input sculpts this to give patterns
Coding carries the information and can be read, like morsecode
Some drugs that increase firing can lead to loss of coding and psychological side effects
Describe lateral inhibition
Activation of excitatory cells also activates associated inhibitory cells
Inhibition acts on neighbouring cells to reduce activity
Strengthens response of cell directly stimulated
Seen in sensory pathways to sharpen - Vision, Touch, Olfaction
What is disinhibition?
Two negatives make a positive
Activation of inhibitory circuit leads to excitation
Pivotal role in Basal Ganglia circuitry – shapes motor function
How do cells synchronise?
Gap junctions
Describe neuronal plasticity
Up- or down-regulation of synaptic strength
LTP long term potentiation and LTD long term depression
Synaptic morphology, Metabolic changes, Subunit changes
What mechanisms are involved in pathogenesis of neuronal and psychological disorders?
Altered neuronal activity Altered synchrony Cellular changes Subcellular change Genetic composition
What is speech?
The act of communicating ideas by the use of words
What is language?
The method of human communication, either spoken or written, consisting of the use of words in a structured and conventional way
What are the components of speech?
Motive force – expiration
Phonation – voice production
Articulation – modification of basic voice sound to create words out of a set of vowel and consonant sound units
Central processing and control
How is the motive force of speech generated?
Inspiration followed by elastic recoil of lungs and wall of thorax +/- contraction of muscles of abdominal wall
Passage of air through glottis down a pressure gradient
What factors may reduce the motive force of speech?
Chest wall deformity
Lung pathology, eg. emphysema, pulmonary fibrosis
Muscular weakness, eg. myasthenia gravis
Airway obstruction, eg. asthma; tracheal stenosis
Exhaustion
What is phonation?
The generation of a voice sound by the passage of air down a pressure gradient over appropriately positioned vocal cords
What determines the pitch of a voice?
Length and tension of the vocal cords and the pressure gradient
What determines the harmony of the voice?
smoothness or irregularity, thickness and consistency of the vocal cords
What determines the volume of a voice?
pressure gradient across the vocal cords
Which laryngeal muscle abducts the vocal folds?
Posterior cricoarytenoid
Which laryngeal muscles adduct the vocal folds?
Lateral cricoarytenoid
Transverse arytenoid
Oblique arytenoid
Which laryngeal muscle lengthens the vocal folds?
Cricothyroid
Which laryngeal muscle shortens the vocal folds?
Thyroarytenoid
What nerve supplies the laryngeal muscles except cricothyroid?
Cranial Nerve X - Recurrent Laryngeal branch
Which nerve supplies cricothyroid muscle of the larynx?
External branch of superior laryngeal nerve of vagus
What position are the vocal folds in during forced inspiration?
Vocal folds abducted and rima glottidis wide open
Vestibule open
What position are vocal folds in during phonation?
Vocal folds adducted and stridulating as air forced between them
Vestibule open
What problems can cause dysphonia?
Laryngitis Vocal cord palsy Vocal nodules Vocal cord polyp Reinke`s oedema Dysplasia Carcinoma
