Trigger 1 Flashcards
how many pairs of nerves are there?
31
name the 4 sections of the spine
cervical
thoracic
lumbar
sacral
what is neural tube closing also known as?
Neurulation
explain the process of neurulation
ectoderm cells differientate into neuro-ectoderm, which thicken to form a neural plate
plate bends dorsally, curving with the neural plate boarders meeting to form the neural tube
neural tube disconnects the neural crest from the epidermus
neural crest cells differientate -> peripheral NS
neuroepithelial cells -> neuroblast, grey matter
Dermatomes
area of skin innervated by 1 spinal cord
what neuro trasmitter is relasesed from the terminal bouton in the somatic NS
acetylcholine
what receptor is on the target organ in the somatic NS
nicotinic acetylcholine receptor
Describe the pre ganglionic neurone in the symapethic NS
short pre-ganglionic
always releases Ach
what neurotransmitter does the post ganglionic symathetic neurone release
noradrenaline
Describe the pre ganglionic neurone in the parasympathetic NS
long preganglinic
release Ach
Describe the post ganglionic neurone in the parasympathetic NS
short
releases Ach
Muscarinic acetylcholine receptor on target organ
which nervous system causes peeing
parasympathetic
what does the symathetic system do to the bladder
relaxs the bladder detrusor muscles
contracts the internal spincter
what is micurition
the act of passing urine
how is continence maintained
maintianed via the spincters of the bladdder and the abdominal pressure compressing the bladder neck
what type of muscle is the internal spincter
an oblique muscle, not well defined
what type of muscle is the urethral spincter
mixed smooth and skeletal muscle
what type of muscle is the external spincter
striated muscle under voluntray control
describe the inital phase of pressure
pressure rises rapidly to a small degree
descibe phase II of bladder pressure
rises slowly, receptice relaxation however most of the bladder fillls, no contractions occur until the bladders has been filled to 400ml
descibe phase III of bladder pressure
pressure rises steeply
which paprasympathetic nerves supply the bladder
pelvic S2-S4 nerves, mixed motor and sensory from the hypogastric and vesicle plexi
which sympathetic nerves supply the bladder
inferior mesenterric ganglia which pass via the hypogastric to the vesicle plexus
outline the steps of micturition
Bladder must be fill to 80% of its contents
the detrusor muscle relaxes which mechaninally opens the internal sphincter and reflexly inhibits the external spincter
flattens the floor of the bladder so the urethra is now open
fluid flows out as the detrusor contracts
flow through the urethra reinforces contracton via the pelvic plexus and spinal reflex
once the smooth muscle has maximally shortened the tension fails and the guard reflex is iniated as the bladder starts to refill
what is the sarcolemma
plasma membrane surronding the muscle
what are t-tubles
between muscle fibres, transmit electrical potential
what is the I band
actin only
what is the H band
myosin only
what is the A band
myosin and actin
describe the excitiation phase of excitation contraction coupling
AP travels to pre-synaptic knob, influx of Ca2+
Ach released from vesicles via SNARE proteins
Ach binds to nicotinic recpetor on the motor end plate
influx of Na+
AP travels along scarolemma and T-tubule
depolaristaion of dihydropyridine receptor casing transformatonal change of L type channel
causes ryanodine receptor to open
CA2+ unbinds from calsequestin and pours into intracellular space
binds to troponin C
outline the contraction phase of excitation contraction coupling
starts in the coked state
ADP+Pi bound to myosin head
Ca2+ enters, binds to troponin C, induces the release of Troponin I
allows troponin-tropomyosin complex to move, exposing myosin binding site on actin filament
myosin cross bridges form and the power stroke occurs
Pi released during
ADP released after stroke
ATPase site is free and binds another ATP molecule
binding of ATP reduces affintiy of myosin head for actin
cross bridges detach
CA2+ returned to lateral sacs via SERCA
What is CSF
a clear liquid that fills the subarachnoid space and ventricles
where is CSF formed
choroid plexuses
what are the choroid plexuses
capillary networks surronded by cuboidal epithelium
how much CSF is produced daily
500ml a day
how much glucose does the csf contain
3.3 mmol/L
60% of the blood
mechanical functions of the CSF
dampen forces
volume of the CSF compartment can undergo minor changes to reduce the changes in intracranical pressure due to alterations in cerebral blood flow
reduces the weight of the brain
metabolic functions of the CSF
maintain constant environment for the brain cells
acts as a lympathic system, draining unwanted metabolities into the venous blood via the arachnoid
provides some nutirents
what are biomarkers
compounds or measurments that show normal functioning of the body, disease process or whether a individual has responded to treatment
what are the properties of good biomarkers
easily obtainable
usually endogenous
sensitive and specific detection method
cost effective
quick results
reproducable and consistent across population
concentration or presence correlates with disease progression or in response to thearpy
what can pass thorugh the blood brain barrier
anything that is a gas or lipophilic
if glucose in the CSF decreses whats could this show?
cells within the CSF are metabolising glucose e.g white blood cells or bacteria
if protein in the CSF increases what could this show?
mengingtis, tumor or white blood cells present
normal level >1%
if IgG in the CSF increases what could this show?
mulitple sclerosis
if WBC in the CSF increases what could this show?
bleeding in the brain
tumor
if neutrophils in the CSF increases what could this show?
bacterial infection
if lymphocytes in the CSF increases what could this show?
viral/myobacterical
what is spina bifida
when a babys spine doesnt develop proplerly causing a gap in the spine
symptoms of spina bifida
weakness/paralysis of the legs
bowel incontience
loss of skin sensations around the legs and bottom
What is hydrocephalus
disturbance of cerebrospinal fluid (CSF) formation, flow, or absorption, leading to an increase in volume occupied by this fluid in the central nervous system (CNS)
What is congential hydrocephalus
change in CSF and volume presnt from birth
casued by conditions such as spina bifida
most babies have pernament brain damage
what is the sarcomere made up of
composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes. Two of the important proteins are myosin, which forms the thick filament, and actin, which forms the thin filament
what is a myotome
the group of muscles that a single spinal nerve innervates.
Motor neurones transmit signals to the myotomes, which allows for movement. Each nerve pair in the spine in linked to one myotome causing the group of muscles to be innervated
what is an odds ratio
An odds ratio is a measure of association between the exposure and the outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure
what is relative risk?
Ratio of the probability of an event occuring in an exposed group to the probability of the event occuring, non-exposed group.
what happens in phase I of clincal trails?
studies assess the safety of the drug or device.
Small sample group, couple months
what happens in phase II of clincal trails?
studies test the efficacy of the drug or device
Large sample group, months to years
what happens in phase III of clincal trails?
studies involved randomized and blind testing
Very large sample group, several years
How do incontinence drugs work
They stop the impulses that tell the bladder to contract by blocking the receptors that receive the impulses. As the drugs can’t specifically target the receptors for the bladder the drugs block all receptors in the body which can lead to side effects.
What nurones form from the alar plate
sensory neurones
Function of Gas
activates adenylate cyclase, increases cAMP
activates PKA =, phosphorylates downstream target proteins
Function of Gai
inhibits adenylate cyclase
Function of Gq
Activates phospholipase C –> increase IP3
DAG + Ca2+ = PKC activation
(smooth muscle contraction)
Funtion of Go
Activates K+ channels
Inhibits Ca2+ channels
How is the Gq subtype targeted in the parasympathetic system to treat incontinence
Gq Muscarinic 3 antagonist (smooth muscle) viseral SM contraction
prevents contaction
How is the Gs subtype targeted in the sympathetic system to treat incontinence
a1 adrencoceptor anatgonists - relax internal spinchter
B3 adrenceptor - enchances bladder relaxtion
What is the pathophysiological mechanism of myasthenia gravis?
Depletion of nicotinic acetylcholine receptors
Which receptors would elicit the most rapid physiological response?
Nicotinic acetylcholine receptor
Urinary incontinence is common in patients with spina bifida.
This is a consequence of damage to which structure?
Sacral nerve
Mirabegron is a selective β3 adrenergic receptor agonist?
What effect will it have on bladder function?
Relax bladder destrusor muscle
Darifenacin is a selective M3 muscarinic receptor antagonist.
What effect will it have on bladder function?
Relax bladder destrusor muscle
