Mental Health and Behavioural Disorders Flashcards
What systems are activated in response to stress?
SNS and hypothalamus-pituitary-adrenal axis
What impact does chronic stress have?
Loss of muscle mass, nitrogen depletion, immune system suppression (decrease in T cells and their production), CVD wear and tear (with ongoing catecholamine surge)
Where are catecholamines produced?
Adrenal medulla (released by Chromaffin cells)
What does the body do in response to stress (real or perceived)?
Hypothalamus releases CRH, causes anterior pituitary to release ACTH, acts on the cortex to secrete cortisol AND aldosterone, medulla to release catecholamines
What happens to the feedback loop as a result of chronic stress?
Negative feedback loop becomes blunted, more cortisol and catecholamines released= wear and tear
What impacts does stress have on the brain?
Impairs hippocampal function (decreases volume, impairs short-term memory, alters regulation of stress response). Can lead to hippocampal atrophy and atrophy of neurons
What are the components of a neuron?
Dendrites (collects electrical signals), cell body (integrates incoming signals and generates outgoing signal to axon), axon (passes electrical signals to axon terminals), axon terminals (release neurotransmitters onto effector cells)
What are the four lobes of the brain and their functions?
Frontal (higher order, personality/behaviour, speech, planning, movement), parietal (somatosensation-pain, pressure, vibration), temporal (hearing), occipital (vision)
What is the role of the cerebellum?
Coordination of movement and balance
What are the functions of the brainstem?
Involuntary functions- breathing, arousal and sleep, eye movement
What is within the basal ganglia?
Caudate nucleus, putamen, globus pallidus, subthalamic nucleus, substantia nigra
What are some of the functions of the basal ganglia?
Initiation and regulation of movement
What are some of the functions of the hippocampus?
Learning and memory**
What are some of the functions of the thalamus?
Integrating center and relay station for sensory and motor function
What are some of the functions of the hypothalamus?
Homeostasis, behavioural drive
What structures are included in the limbic system?
Hippocampus, fornix, thalamus, amygdala, olfactory cortex, and cingulate gyrus
What are some of the functions of the limbic system?
Sets level of arousal, involved in motivation, reinforcing behaviours, regulates autonomic and endocrine function in response to emotional stimuli
How are neurotransmitters released?
Action potential reaches the axon terminal and activates Ca2+ channels, enters and stimulates exocytosis, neurotransmitters released into the synaptic cleft and bind with their receptors
How are neurotransmitters removed from the synaptic cleft?
Via diffusion, enzymatic digestion, reuptake
How are mental illnesses seperated?
Into alterations in thinking, mood, or behaviour
What is thought to contribute to MOST psychiatric disorders/mental illness?
Excessive CNS stimulation (except depression)
What are the three neurotransmitter systems?
Noradrenergic system, serotinergic system, dopaminergic system
What are the functions of the noradrenergic system?
Maintaining emotional tone (mood, arousal, wakefulness, reward), decrease associated with depression, increase associated with mania
What are the functions of the serotonergic system?
Active in maintaining sleep-wake cycle, emotional tone, sensory perceptions (pain), increase associated with schizophrenia, decrease associated with anxiety and depression
What are the four tracts of the dopaminergic system?
Nigrostriatal tract, tuberoinfundibular tract, mesolimbic tract, mesocortical tract
What are the different mood disorders?
Depressive, bipolar, anxiety, trauma and stressor related disorders including OCD and PTSD
What is dysthymia?
Persistent depressive disorder
What is bipolar I disorder?
Classic manic-depressive disorder
What is bipolar II disorder?
One episode of hypomania (milder forms of mood elevation) and major depression
What is the neurochemical dysregulation hypothesis of major depression?
Monoamine hypothesis suggests MDD result of decreased norepinephrine, serotonin, and/or dopamine levels within the synaptic cleft
What other neuroanatomic and functional abnormalities are seen in major depression?
Altered serotonin receptor expression, alterations in the norepinephrine system, changes to cerebral blood flow
What are some of the pathophysiological processes thought to contribute to bipolar?
Genetics, neurochemical dysregulation (increased levels of serotonin, dopamine, norepinephrine), alterations in neuroendocrine system, increased ventricular volume, reduced prefrontal cortex, inflammatory component
What pathophysiological changes occur in generalized anxiety disorder?
Decreased serotonin secretion/increased reuptake, genetics, alterations in distribution of benzo receptors
What are some clinical manifestations of PTSD?
Lack of concentration, flashbacks to event that cause destress and emotional numbing, hyperviligance, irritability, sleeping difficulties, exaggerated startle
What pathophysiological processes occur in PTSD?
Decreased volume of the hippocampus, decreased benzo receptor distribution in prefrontal cortex
What is the role of GABA?
Blocks signals in brain and results in calming effect, controlling nerve cell hyperactivity
What is the pathophysiological process behind OCD?
Abnormal communication b/t basal ganglia and prefrontal cortex, increased activity in the prefrontal cortex, decreased serotonin synthesis
What is an example of a thought disorder?
Schizophrenia
What characterizes schizophrenia?
Disorganized thoughts, often in the form of hallucinations, delusions, cognitive defects. Dysfunctions with perception, emotion, language, memory and judgment
What are positive symptoms in schizophrenia?
Situations where individual loses touch with reality and experiences something that should be absent (hallucinations, delusions, disorganized speech)
What are negative symptoms in schizophrenia?
Absence of something that SHOULD be occurring (affective flattening, anhedonia, alogia (inability to speak), avolition (lack of interest in goal directed behaviour)
What is the role of glutamate?
Abundant excitatory neurotransmitter, plays role in memory, cognition and mood regulation
What are some of the neurotransmitter alterations in schizophrenia?
Decreased GABA production in dorsolateral prefrontal cortex, decreased glutamate production, brain dopamine tracts altered
What occurs in the dopamine tracts in schizophrenia?
Mesolimbic looks at emotion, rewards, memory and motivation (innervates hippocampus, amygdala, nucleus accumbens). Increased dopamine release in these areas= positive symptoms. Mesocortical involved in motivation and emotion (innervates dorsolateral prefrontal cortex), decreased dopamine reduces the activation= negative symptoms
What is the key neurotransmitter in schizophrenia?
Dopamine, increased levels
What are some examples of behavioural disorders?
Habituation and addition, eating disorders
What occurs with dopamine in addiction?
Drugs of abuse activate the brain-reward pathways, have increase amount of dopamine in the synaptic cleft= sensation of reward, need larger amounts of dopamine to produce the same effect over time
What are the key eating disorders?
Anorexia, binge eating disorder, bulimia nervosa
What is the role of serotonin in eating disorders?
Disturbances in serotonin could contribute to appetite dysregulation, anxious and obsessional behaviours, extremes of impulse control. See decreased levels of serotonin
What is the primary response of norepinephrine?
Vasoconstriction, stimulation of the A1 adrenergic receptors
During a synapse, what change occurs after the neurotransmitter binds to the receptor?
Permeability of the postsynaptic neuron changes and consequently its membrane potential
What are cholinergic receptors?
A part of the parasympathetic nervous system. Binds to acetylcholine
What are adrenergic receptors?
A part of the sympathetic nervous sytem, binds catecholamines
Can chemical synapses between neurons send messages in both directions?
No- neurotransmitter is stored on one side of synaptic cleft and receptor sites are on the other side
List some of the lab values that may be abnormal in someone with anorexia.
Electrolytes, glucose, estrogen and sex hormones, kidney function, thyroid function, iron, acid/base imbalances, may see leukopenia/anemia/thrombocytopenia
