IC2- CNS Flashcards
What is the difference between an afferent and efferent neuron?
Afferent: carries signal from periphery to CNS
Efferent: carries signal from CNS to periphery
What is the name of a touch receptor?
Pacinian corpuscle
Describe the nerve ending of the pacinian corpuscle and how the neuron is myelinated
- Enclosed nerve ending by layer of connective tissue
- Aβ myelinated
What are the different types of myelination? What kind of receptors are they?
- Aβ (touch)
- Aδ (pain)
- C (pain)
How does the myelination help in conduction of signal?
Rank the myelinations in terms of conduction speeds
More myelination → faster conduction
Speed: Aβ (thick myelin) > Aδ (thin myelin) > C (no myelin)
Describe the nerve ending of afferent neurons (pain receptors)
Free nerve ending (selectivity conferred by TRPV1 receptor in membrane of nerve ending)
Which tissue-damaging stimuli are the pain receptors activated by?
Pain receptors (afferent Aδ and C) are activated by tissue damaging stimuli: mechanical, thermal, chemical (ingredient of chilli/ capsaicin)
What happens if there is loss of Aβ fiber (touch receptor)?
What happens to their pain sensation?
- Loss of non-pain sensation
- Pain sensation remains the same
What happens if there’s a loss-of-function mutation in NTRK1 gene located on chromosome 1q21-22?
Absence of NGF (nerve growth factor)-dependent Aδ or C fibers → insensitivity to pain stimuli
What is the postsynaptic target for an excitatory synapse?
Dendrite
What is the postsynaptic target for an inhibitory synapse?
Soma (cell body)
What happens during the upstroke of the action potential? (what channel is involved?)
First, threshold potential results in opening of a class of channels in membrane = voltage gated Na+ channel
When the action potential reaches the axon terminal, it opens the voltage-gated Ca2+ channels → Ca2+ influx → causes vesicles containing neurotransmitter to fuse with presynaptic membrane and exocytosis
What happens during the upstroke of the action potential? (what channel is involved?)
- Inactivation of voltage gated Na+ channel
- Opening of voltage gated K+ channel causing K+ efflux → RMP restored
In hypokalemia, there is a severe decrease in serum K+. What happens to the excitable membrane?
Hyperpolarisation as the concentration gradient favours movement of K+ from intracellular → extracellular; cell less excitable
What are the limbic structures in the brain? (ie. structures largely responsible for regulating emotions)
Hippocampus and amygdala
Which part of the brain is associated with consciousness?
Cortex
What are the functions of the cortex?
- Sensation and perception (both cortices)
- Voluntary control of movement
- Personality traits (frontal lobes)
- Learning and memory
- Language
What could damage to the Broca’s area (left hemisphere) result in?
Damage lead to difficulties in expressing language
What could damage to the Wernicke’s area (left hemisphere) result in?
Damage leads to difficulty in comprehending language
What is the term used to describe the symptom of difficulty in producing or comprehending speech due to damage in the Broca/ Wernicke’s area?
Aphasia
Which region of the brain is correlated with depression?
Elaborate
A region in the prefrontal cortex, the ‘Subgenual Anterior Cingulate Cortex’ or ‘Subgenual ACC
Depression is correlated with increased activity (hyperactivity) of Subgenual ACC
What is a type of Tx that can decrease depression?
Deep brain (electrical) stimulation to decrease activity in Subgenual ACC
Which part of the brain is associated with cognition (learning and memory), emotion, mood?
Both cortical and sub-cortical regions
What is the hippocampus associated with? What happens if there is a lesion/ neurodegeneration of cells in the hippocampus?
What disease is implicated?
Associated with declarative memory that involves conscious recall; e.g., memory of events, names, numbers etc
Alzheimer’s disease
What is the amygdala associated with? What happens if there is damage to the amygdala?
Amygdala = emotion and emotional memory, important for mood changes
Lost ability to recognize facial expression of emotion
