L24 - reflexes and senses Flashcards
reflex pathway in arm
- output provided to agonist muscle to contract so lower part of arm lifts up
- antagonist muscle
main inhibitory NT in CNS
GABA
flexor/ extensor reflex
- step on something you don’t want to
- leg lifts up
- mechanoreceptor activated in foot causes A.P to go to spinal cord
- neurones triggered to cause legs to flex or extend muscles
other types of reflexes
changes in pupil size due to light or focus
do reflexes have to involve spinal cord?
no
cranial nerves
nerves go in and out of brain instead of spinal cord
the eye
- iris sphincter muscle controls diameter of pupil
- cillary muscle controls thickness of lens to focus light in retina
how does eye work?
photons of light being focused to back of eye
rodes
helps you see in low light and in ur periphery
cones
for colour perception, respond to different wavelength of light.
pupil constriction reflex
shine bright light in eye, reflex action to restrict pupil as iris gets bigger, protects back of eye from being exposed to light
what does the optic tract do?
innverates the brain stem (area called pretectal nucleus), which in turn innervates the oculomotor nerve
association cortex / areas
- interprets what visual cortex tells brain what eyes see
- neuronal input from auditory cortex is interpreted (allowed us to have language) - frontal lobe involved in what it means
touch receptors
nerve endings that respond to mechanical stimulation (skin moving), this opens ligand gated ion channels open, so Na+ enter cell, depol, A.P triggered
receptive field of touch receptors
- pacinian corpusle
- receives touch from wide area of skin
sense of taste
- specialised cells in taste buds which have receptors which respond to chemicals in food
- 5 taste receptors
- sweet, salt, sour, bitter, umami
sense of smell
chemicals in air activate G protein coupled receptors in nose. 300 diff smell receptors which respond to different chemicals. sense of smell more diverse than taste.
the ear
sound waves go into ear and activate the ear drum (tympanic membrane), this vibrates at same frequency as sound wave, vibration passes into inner ears, causing hair cells in inner ears to bend (receptors that respond to mechanical stimulation)
