sensory nervous system (sensation and pain), motor nervous system, muscle, special senses Flashcards
what are the sensory and motor parts responsible for
Sensory - skin senses (pain, temp etc), proprioception (detecting relative position of parts of the body) special senses (smell, taste etc) Motor - skeletal muscle movement
the somatic nervous system has 2 functional parts, what are they and which lobe controls which
Sensory system - parietal lobe
Motor system - frontal lobe
what is the 5 stage somatosensory system (stages in which sensory signals are processed)
1) activation of sensory receptor e.g skin
2) Transmission of signals into CNS via peripheral nerves
3) Relay of signal ascending pathways in sensory cerebral cortex
4) processing of signals in sensory cerebral cortex
5) sensation - perception (you feel it)
where do sensory neurons enter the spine
dorsal horn
where do motor neurons enter the spine
ventral horn
where does the first of the 3 nerves of the dorsal column pathway (fine touch, limb position) synapse
in the medulla (crosses over here)
where does the first of the 3 nerves of the spino-thalamic pathway (pain, temperature) synapse
in the spine (crosses over here)
where is the emotional component on which drugs can act to remove pain
hypothalamus
how does referred pain work
nociceptors in some parts of the body share interneurons in segments of the spinal cord. For example cardiac pain felt in the arm is due to skin of left arm (common signal) and heart (rare signal) sharing T1-T5 in spinal cord. The cortex interprets signal as from common site.
where do motor neurons enter the brain
precentral gyrus
where do sensory neurons enter the brain
postcentral gyrus
what do LMN’s (Lower Motor Neurons) do and where are they found
innervate skeletal muscle (alpha and gamma)- found in spinal cord or cranial nerve nuclei
what do UMN’s (Upper Motor Neurons) do and where are they found
control LMN’s - found in brain
what is a motor unit
a single motor neuron plus its bundle muscle fibres (muscle unit)
what dictates the strength of a muscle contraction
number of motor neurons activated and frequency of action potentials in motor neuron
what are examples of symptoms of Lower Motor Neuron Lesions
weakness, hypo-reflexia - tonia, wasting, fasciculation
what are examples of symptoms of Upper Motor Neuron Lesions
weakness, no wasting, hyper-flexia-tonia
are tendon jerks mono or poly synaptic
monosynaptic
are withdrawal/flexor reflexes mono or poly synaptic
polysynaptic
what are the 3 types of muscle and what do they look like
skeletal - striated (striped) multi-nucleate, non-branched
smooth - striated, single nucleus, branched (intestines)
cardiac - non-striated, single nucleus, tapered (heart)
what is the word which means muscles work together
synergistic
what is the word which means muscles work in opposite directions
antagonists
what is the major muscle called
prime mover
what are stabilising muscles around prime mover called
fixators
what are muscles mostly made up of
contractile proteins
what are the 3 types of muscle fibre
Type I - slowly contracting, low force, high endurance (walk)
Type IIA - fast contracting, medium force, high endurance (run)
Type IIB - fast contracting, high force, low endurance (sprinting)
what is a muscle unit
just the muscle fibres innervated by a motorunit
how does sliding filament mechanism/muscle contraction work -3 things
contraction occurs when…
1) thick filaments (myocin) link (crossbridges) to thin filaments (actin) - calcium irons essential for crossbridge formation
2) thin filaments slide over thick filaments = power stroke
3) uses ATP
When is ATP required in muscle contraction
for relock (not contraction)
what is an isometric contraction
muscle develops tension but does not shorten (touching box ready to lift)
what is an isotonic contraction
muscle shortens, tension remains constant (lifting box)
what is an isotonic, eccentric contraction
muscle lengthens whilst maintaining tension (lowering box down)
when do you get optimum stretch
when the most cross bridges are formed (middle of their length)
what are the 5 steps of muscle contraction from point of action potential generation
1) action potential in motor nerve
2) release of chemical messenger (neurotransmitter=acetycholine) at synapse
3) action potential in muscle fibres
4) cross-bridge links formed between thin and thick filaments (needs calcium)
5) muscle fibres contract
how do the eyes work
detect visible light in the form of colours
what is the conjunctiva
the epithelial layer that lines inner surface of eyelid and covers outer surface of the eye
what is the name of the gland which produces tears
lacimal gland
In the eye how many fluid filled cavities are there and what are they called
2 (the anterior and posterior cavity) separated by the lens
what is the wall of the eyeball made up of
3 layers (tunics) fiberous (outside) vascular and neural (inner)
what is the fiberous tunic made up of
sclera (white of eye) and cornea (transparent layer which covers iris and pupil)
what is the vascular tunic made up of
consists of the iris (pigmented area), ciliary body (thickened region which contains suspensory ligaments) and choroid (capillary network). also contains blood vessels, smooth muscle.
what is the neural tunic (retina) made up of
contains photoreceptors called rods and cones which respond to light. (more rods than cones) rods and cones synapse with sensory cells whose axons converge to form optic nerve
what is the optic disc
site where optic nerve enters and blood vessels leave/enter. no photoreceptors so also known as blind spot
what is fovea centralis
Area of eye with only cones no rods. light is most focused here when looking at an object
what is the anterior cavity of the eye made up of
the anterior cavity is made up of anterior and posterior cavity separated by the iris and contains a watery fluid (aqueous humour) that nourishes the lens and cornea.
what is the posterior cavity of the eye made up of
the posterior cavity (vitreous chamber) is filled with vitreous humour - a jelly like substance that maintains pressure within the eye
what are the 3 steps of vision
1) iris allows light into eye
2) light focussed onto retina by the cornea lens and humours
3) as light strikes retina action potentials are transmitted to brain via optic nerve
where does the optical nerve leave the eye and enter the brain
leaves the orbit and enters cranial cavity. Axons from the optic chasm pass to the visual cortex in the occipital lobe
what are the 3 parts of the ear
external, middle, inner
what is the external ear made up of
auricle - fleshy outside supported by cartiladge
tympanic membrane - (eardrum) separates external and middle ear, vibrates
external acoustic meatus - passageway, contains glands (wax) hairs
what is the middle ear made up of
contains 3 auditory ossicles (ear bones) malleus, incus and stapes which transmit vibrations from tympanic membrane to oval membrane (tympanic 20x larger than oval so amplified)
what is the middle ear connected to and what is it connected by
nasopharynx - connected by Eustachian tube
what is the inner ear made up of
interconnecting fluid filled and bony channels within temporal bone.
cochlear (hearing)
vestibule and semicircular canals (balance)
vestibuloclear nerve transmits information from receptors to the brain
what are the 5 steps of sound transmission
1) sounds waves collected by auricle and conducted through the external ear
2) sounds waves hit tympanic membrane and cause vibration
3) vibration is transmitted and amplified through the ossicles
4) vibration of stapes on oval window causes fluid on cochlea to vibrate
5) vibrations stimulate the spiral organ (sensory receptor) which triggers action potentials in the vestibularcochlear nerve
where is sensory information from the cochlea sent
to the primary auditory cortex in the temporal lobe
what are the two types of hearing impairment
conduction deafness - mechanical deficiency with soundwave reaching sensory receptor
sensorineural deafness - involves the spiral organ, neural pathway or primary auditory pathway
which 2 parts of the ear are concerned with static equilibrium (position of the head)
the utricle and saccule make up the vestibule (small entrance or hall)
what parts of the ear are concerned with kinetic equilibrium (change in direction or rate of head movement)
the semicircular canals
what are the airborne smell molecules that we smell called
oderants
what are the 4 steps of smell detection
1) oderants enter the nasal cavity and dissolve into the mucus
2) detected by receptor proteins on olfactory (smell) epithelium (upper region of nasal cavity)
3) olfactory nerve stimulated
4) info transmitted to olfactory cortex (brain)
where are taste buds located
tongue, soft palate, pharynx and epiglotis
what are the 4 steps of taste
1) tastants bind to receptors on hair cells
2) action potential initiated in sensory neurone
3) sensory axons for taste are contained in the facial glossopharangeal and vagus nerves
4) information transmitted to taste cortex in pariental lobe
what are total loss, partial loss and taste distortion called
distortion - dysgeusia
partial loss - hypogeusia
total loss - ageusia
What makes up a muscle
Collection of muscle fibres
What are muscle fibres made up of
Myofibrils
