S3C6 (2.0) Flashcards
What are the 5 key principles of the mental capacity act?
A personis assumed to have capacity unless it is established otherwise
A person is not to be treated as unable to make a decision unless all practicable steps to help him to do so have been taken without success.
A person is not to be treated as unable to make a decision merely because he makes an unwise decision.
An act done, or decision made, under this Act for or on behalf of a person who lacks capacity must be done, or made, in his best interests.
Before the act is done, or the decision is made, regard must be had to whether the purpose for which it is needed can be as effectively achieved in a way that is less restrictive of the person’s rights and freedom of action.
What is the role of afferent neurones?
Neurites in sensory surfaces of body
Detect changes in environment
Transmit information to brain or spinal cord
What is the role of association neurones?
Lie between sensory and motor pathways
Connect only with other neurones
Process, store and retrieve information
What is the most abundant neurone type?
Interneurons
90% of neurons
What is the role of efferent neurones?
Axons form synapses with muscles
Command movements
Where are bipolar neurons found?
Olfactory, retina and ear
What are multipolar neurones?
Many dendrites to one axon
What is the role of unipolar neurones?
Sensory from skin and organs to spinal cord
Long myelinated fibre bypassing soma
How do neurons communicate?
Axon terminals form synapses with dendrites or soma (cell body) of other neurones
Nerve impulse arrives in axon terminal and releases neurotransmitter
Neurotransmitter binds to specific receptors
Generation of electrical signal in postsynaptic cell
Triggers action potential
Messaged gets passed on
What is the major excitatory neurotransmitter?
Glutamate
What is spatial summation?
Adding of EPSPs generated simultaneously on multiple presynaptic inputs
What is temporal summation?
Adding of EPSPs generated in quick succession at same synapse
What are glia?
non-neuronal cells in the central nervous system. They maintain homeostasis, form myelin and provide support and protection for neurons
What is the role of glia on neurones?
Synapse formation
Synaptic strength
Co-ordination of activity
What is the role of neurones on glia?
Proliferation
Differentiation
Myelination
What are the two types of potential?
Electronic potential
Action potantial
What is an electrotonic potential?
Non-propagated local potential, resulting from a local change in ionic conductance (e.g. synaptic or sensory that produces a local current). When this spreads along a stretch of the neuronal membrane, it becomes exponentially smaller
Where can you find cells using electrotonic potentials?
Amacrine cells in retina
What is an action potential?
A propagated impulse.
Longer neurons utilise electrotonic potentials to trigger the action potential.
Initially, there is always an electrotonic potential in a neuron – when this propagates, it becomes an action potential.
What is the resting potential of neurons?
-70mV
Where is the concentration of K+ higher?
Inside neurons
What are the two gates on sodium channels?
the activation gate (m gate)
the inactivation gate (h gate).
What gate on the Na+ channels are closed during resting state?
The activation gate is closed, which prevents any entry of sodium ions to the interior of the fibre through these sodium channels.
When does the absolute refractory period occur?
Na+ channel inactivation.
It is impossible to recruit a sufficient number of Na+ channels to generate a second spike unless previously activated Na+ channels have recovered from inactivation.
What are the 3 categories of neurotransmitter?
Amino acids
Amines
Peptides
What neurotransmitters are amino acids?
Glutamate
GABA
Glycine
What neurotransmitters are amines?
Acetylcholine Noradrenaline Dopamine Serotonin Histamine
What neurotransmitters are peptides?
Substance P
Opioids (encephalin and dynorphin)
NPY
What are the two types of receptors?
Ionotropic
Metabotropic
How do ionotropic receptors work?
Glutamate is released at the pre-synapse terminal, binds to channels on the post synaptic cleft, causing influx/efflux of ions, thereby causing an action potential
How do metabotropic receptors work?
Binding of transmitter leads to activation of G-proteins.
G-proteins activate effector proteins:
Ion channels
Enzymes that generate 2nd messengers
Slower and longer lasting effects than ionotropic receptors
What is the epidemiology of depression?
Woman > Men
Peak onset is 20s
What are factors for depression?
Genetic, neurobiological, sociopsychological and environmental factors
What are the biological factors of depression?
Lack of monoamines
Genetic vulnerability
Increased levels of stress hormones and dysfunction of the hypothalamus-pituitary axis
What are the psychological factors of depression?
Traumatic and stressful experience
Personality factors - learned helplessness
What is the concordance rate in identical twins for depression?
50%
What are the clinical features of depression?
Depressed mood, present most of the day, every day
Sleep disturbance (insomnia or hypersomnia)
Loss of interest or anhedonia
Feelings of worthlessness or guilt Fatigue
Diminished concentration, ability to think or make decisions-Pseudodementia
Weight change due to appetite changes
Psychomotor changes
Suicidal ideation
What is the diagnostic criteria for depression?
5 or more symptoms for at least 2 weeks, one of them being depressed mood or anhedonia
What is adhedonia?
An inability to enjoy acts or experiences that are normally pleasurable
What are the positives of Buproprion?
lowers seizure threshold, less sexual dysfunction compared to SSRIs, and can also treat tobacco dependence
What is the role of glia?
Insulate and support and nourish neurons
What are microglia?
the resident macrophages of the brain and spinal cord, and thus acts as the first and main form of active immune defence in the CNS
What % of glial cell population in the brain are microglia?
10-15%
What is the role of oligodendrocytes?
Involved in myelin formation around axons in the CNS
These provide layers of membrane that insulate axons forming a sheath
What are the subtypes of astrocytes?
Fibrous - found primarily in white matter
Protoplasmic - found primarily in grey matter
What is the role of astrocytes?
Send processes to blood vessels where they induce capillaries to form the tight junctions making up the BBB
They also send processes that envelop the synapses and the surface of the nerve cells
What is the role of protoplasmic astrocytes?
Protoplasmic astrocytes have a membrane potential that varies with the external K+ concentration but do not generate propagated potentials
They produce substances that are tropic to neurons, and they help maintain the appropriate concentration of ions and neurotransmitters by taking up the K+, glutamate and GABA