Neuromuscular system physiology Flashcards
what are exteroreceptors? (3), and where they are found (3)
- sensory receptors
- detect stimuli external to body
- e.g. touch, pressure, temperature
- found on skin, nose, tounge
what are enteroreceptors? (2), and where they are found (2)
- sensory receptors
- that detect internal stimuli within the body
- found in glands and smooth muscle
what are proprioceptors (2), and where they are found (3)?
- sensory receptors
- detect position, movement and orientation of body
- found in skeletal muscle, tendons, & joints
what does the NMJ essentially do?
connection between axonal efferent and muscle fibre
what is the neurotransmitter released across NMJ’s?
acetylcholine
what does acetylcholine bind to on the muscle cell surface membrane?
nicotinic Ach receptors
what electrical gradient indirectly causes contraction of muscle (2)
- depolarisation
- causes Ca2+ influx
how does depolarisation occur in skeletal muscle? (4)
- acetylcholine receptors bind to Ach
- allows Na+ to enter muscle cell
- triggers further voltage-activated Na+ channels to open
- Massive iflux in NA+ causes depolarisation of skeletal muscle
what causes Ach infused vesicles to fuse with plasma membrane? (2)
- action potential-driven depolarization
- Ca2+ influx to presynapse
how are body movements classified?
- the type of neuronal control
which is higher order and why: postural reflex movements or autonomic reflexes?
Postural reflex movements:
* involves midbrain as well as spinal cord
what nerve transmits information about head movement to the vestibular nuclei?
the 8th cranial nerve
at what age do babies establish basic postural reflexes?
6-7 months
what particular function of the Basal ganglia is impaired in Parkinsons’s disease?
- scaling of motor output
is there any direct projections from the Basal ganglia to the Spinal cod?
no
is there direct sensory input from the periphery to the basal ganglia?
no
what 3 main disorders can occur due to disfunction of the basal ganglia?
- parkinson’s isease
- huntington’s disease
- dystonia
what is a cortical pathway?
- refers to a neural pathway within the cerebral cortex
what is the cerebral cortex?
- outer layer of the brain
- responsible for higher cognitive functions such as perception, decision-making and voluntary movement
what are the ipsilateral white columns? (2)
- part of the spinal cords white matter
- responsible for transmitting sensory information from same side of body to brain
what does the somatosensory cortex do?
allows you to sense movement of the body
what are the 3 anatomical levels in the nervous sytem that control voluntary movement?
- cerebrum - cortex, basal ganglia
- cerebellum - motor patterns, refinement, execution
- ** brain stem & midbrain** - relay systms of higher brain regions
what is the mass of skeletal muscle relative to the whole body in men and women?
men- 40%
women - 30%
how is acetylcholine removal from the synaptic cleft?
acetylcholinesterase
how does DHPR cause Ca2+ release?
- not entirely known
- thought to be through protein-protein interaction
- this idea comes from the speed of the process as its so quick
what is calsequestrin? (2)
- a protein that binds to calcium
- allows lots of calcium to be stored in the SR
what is Rigor mortis, and how does it occur?
- post-death phenomon characterized by stiffening of muscles
- occurs due to depletion of ATP
the percentage of ATP used in different aspects of muscle contraction?
- myosin ATPase - 60%
- Ca2+ ATPase - 30%
- Na-K ATPase - 10%
what does the turnover rate of ATP mean?
- the rate at which ATP are synthesized and hydrolysed within a biological system
- Resting turnover rate - 1 minute
- increase 10-100 fold during exercise
how do skinned muscle fibre cells stay intact?
- unlike most cells, skeletal muscle cells have a very strong organised structure
- allows for structure to stay intact even when the plasma membrane is removed
why would it be fatal if ATP levels depleted in intesnse exercise?
- calcium stores would become depleted
- calcium levels could increase so much that sustained contraction of the muscle cell occurs
- equivalent to a cell undergoing necrosis
what is anoxia?
when something is in a state of no oxygen
What is the reason why phosphate effects muscle contraction, force and sensitivity to Ca2+ (2)
- power stroke generation in cross bridge cycle
- higher concentration of phosphate slows down the kinetics of the phosphate release from ADP during this stage
what types of remodelling occur in response to intense exercise?
- innervation
- blood flow
- extracellular matrix
what is succinate? (4)
- a dicarboxylic acid
- involved in the kreb cycle
- undergoes oxygenation in Kreb cycle to fumarate
- leads to production of ATP through oxidative phosphorlyation
