MD2001 Week 9 Flashcards
what does the speed of a nerve impulse depend on? (2)
- diameter of the axon
2. whether axon is myelinated or not
how does diameter of nerve cell affect how nerve impulse passes? (2)
- resistance
2. capacitance
normal conductance rate of action potential
10m/s
what increases the frequency of the action potential?
an greater depolarizing current increases this
multiple sclerosis
disease attacking oligodendrocyte myelin
where do action potentials occur on a myelinated nerve cell?
they occur at the nodes of ranvier
what diameter would a nerve have be better off unmyelinated?
it would have a diameter
outline the common sense model
health message -> representation of illness risk -> coping procedures -> appraisal
5 components of illness perception
- identity
- consequence
- timeline
- cause
- cure
define health promotion
process of enabling people to take control over and improve their health
downstream vs upstream causes
downstream: immediate (ex. infectious agent)
upstream: source (ex. education)
top-down vs bottom-up priorities
top-down: priorities set by health promoters
bottom-up: priorities set by individuals
5 approaches to health promotion
- medical/preventive approach
- behavioural change approach (ie. persuasive education)
- education approach (ie. provide info and let them decide)
- empowerment approach
- social change approach
incidence vs prevalence
incidence: # of new cases
prevalence: proportion of pop w/ disease
calculate (absolute) risk
number of events/total population at risk
calculate relative risk
risk in group 1/risk in group 2
calculate (absolute) risk difference
risk in group 1 - risk in group 2
calculate relative risk reduction
(1-relative risk) x 100
calculate number needed to treat (to save one person)
1/absolute risk reduction(difference)
what does odds ratio find?
what calculation determines if a factor is more likely to occur in a particular group of people
rate ratio
ratio b/w two mortality rates
hazard ratio
rate ratio for a certain period of time
confidence intervals
a range of plausible values
cross-sectional study
snapshot of a pop without follow-up; to find prevalence
case-control study
look at differences in exposure b/w cases with outcome and cases without outcome; to find cause
cohort study
select cases w/ exposure and cases w/out exposure and follow up on outcome; to find cause/prognosis/incidence
randomized controlled trial (RCT)
group random ppl into intervention or control then compare risk of outcomes b/w groups; to find treatment effect
confounding
true relationship “confused” by a third factor
3 stages of treatment delay
- appraisal delay: time to interpret a symptom as illness
- illness delay: time b/w recognizing illness and seeking help
- utilization delay: time b/w seeking help and using health services
3 types of violence
- self-direction
- interpersonal
- collective
3 levels of violence prevention
- primary “upfront” - taking action before risk factor emerges
- secondary “in the thick” - reacting to presence of risk factors
- tertiary “aftermath” - reducing re-occurence of violence
how many cervical vertebrae are there?
there are 7 of these vertebrae
what is the synovial joint found in vertebrae?
zygapophyseal joint
what is the secondary cartilaginous joint found in vertebrae?
intervertebral discs of fibrocartilage
what levels of vertebral column lies the posterior longitudinal ligaments?
this ligament lies from C2-sacrum
what levels of vertebral column lies the anterior longitudinal ligaments?
this ligament lies from occipital bone to sacrum
what ligaments connect the articular laminae?
ligaments flava
what levels of vertebral column lies the ligament niche?
this ligament lies from foramen magnum-C7
what does the anterior longitudinal ligament continue as at the top?
this ligament continues as the ant. atlanto-axial and atlanto-occipital membranes
what does the posterior longitudinal ligament continue as at the top?
this ligament continues as the tectorial membrane
what ligament continues as the pos. atlanto-axial and atlanto-occipital membranes?
ligamentum flavour continues as this at the top
what ligament joins the dens and the foramen magnum and stops excess rotation?
alar ligament
ligament that prevents excess movement b/w axis, atlas and occiput, and holds dens and atlas together
cruciate ligament
what are the veins b/w the body and spine of vertebrae called?
internal vertebral venous plexus
what 3 muscles lie inferior to the trapezius?
- levator scapulae
- rhomboid minor
- rhomboid major
what does the trapezius extend to longitudinally?
this muscle extends from skull to T12
what does the trapezius do?
this muscle extends neck, retracts, and abducts scapula
what is the latissimus dorsi connected to?
this muscle is connected to the iliac crest, spines T6-T12, lower ribs, humerus
what muscle moves the shoulder joint?
latissimus dorsi does this
what muscle raises and adducts the scapula?
levator scapulae does this
what do the splenius capitis and cervicis connect to?
these muscles connect to skull, transfer processes, ligament nuchae, C and T spines
what do the splenius capitis and cervicis do?
these muscles extend, rotate, and laterally flex the neck
these muscle connect to skull, trans processes, spine, supraspinous ligaments, ribs
erector spinae connect to these bones
what 3 sections is the iliocostalis muscle divided into?
this muscle is divided into cervicis, thoracis, and lumborum
what is the deepest layer of intrinsic back muscle?
transversospinalis
what is the highest transversospinalis muscle?
semispinalis is the highest muscle in this group of muscles
what muscles make up the sub-occipital triangle of muscles?
rectus capitis + oblique capitis
characteristic of electrical synapses?
synaptic clefts touch in this type of synapse
size of gap b/w synaptic clefts
20nm
how do peptide neurotransmitters move across nerve?
- pre-peptide precursors and enzymes move down microtubule tracks
- enzymes modify peptide neurotransmitters
- NTs transmit message then diffuse away and is degraded by proteolytic enzymes
neurotransmitter steps in bouton (5)
- budding
- storage
- docking
- priming
- exocitosis
list the SNARE proteins (4)
- SNAP-25
- syntaxin
- synaptobrevin
- synaptotagmin
types of post synaptic potential summations (2)
- spatial summation
2. temporal summation
differences b/w EPSPs and action potentials (4)
- do not move along axon
- no voltage gated currents; caused by ligand gating
- Na+ and K+ flow through same channel
- no refractory period
how do local anaesthetics work?
they work by reversibly blocking voltage-gated Na+ channels
put these in order of loss by local anaesthetic: proprioception, skeletal muscle tone, pain, temperature
- pain
- temperature
- proprioception
- skeletal muscle tone
what does the ability of a local anaesthetic depend on? (5)
- diameter of axon
- myelination status
- length of nerve
- length of time exposed to drug
- drug concentration
does drug become more ionized or unionized when pH decreases?
drug becomes more ionized when pH does this
what does the lasting effect of an ester- containing local anaesthetic depend on? (3)
- blood flow
- action of plasma esterases
- hydrophobicity of drug
risk of administering adrenaline
administering this lends a risk to ischaemia
side effects of local anaesthetic
- dysrhythmias
- sudden fall in BP
- CNS issues: restlessness, tremors, convulsions, etc. (due to less binding of IPSPs)
channelopathy
condition resulting from mutation in channel function
conductance
1/resistance; reflects number of ion channels open at a moment
optimum pH extra and intracellularly for local anaesthetic effect
basic extracellularly, acidic intracellularly
what does the specificity theory of pain propose?
this theory proposes that pain has a separate sensory system
what does the pattern theory of pain propose?
this theory proposes that pain results from pattern of type of stimulation
