MIDTERM Flashcards
Sensory receptors
Detects environmental stimuli
Adequate stimulus
The type of environmental stimuli that sensors are most able to detect (most sensitive to)
Generator potential (Def and 4 characteristics)
Def: The local depolarization caused by a change in ion permeability following the detection of a stimulus by a sensory receptor
4 characteristics:
Depolarizing but can be hyperpolarizing too
Caused by increase in permeability to Na+ (or K+ for hyperpolarizing)
LOCAL – decrease with time and distance from the stimulus
Proportional to strength of stimulus
Can be summed
List the receptors responsible for touch, vibration, temperature, pain, and proprioception (limb position and movement).
fine touch: hair follicle
touch: Meissner’s corpuscles, ruffini’s corpuscles, pacinian corpuscles
vibration: hair follicle, Meissner’s (LOW), Pacinian (HIGH)
pain and temp: free nerve endings
receptive field
Area on skin that would activate a receptor
Spinothalamic (anterolateral) tract
The first order neuron enters the spinal cord and immediately crosses over to the contralateral side when it synapses with the second order neuron
The neuron ascends to the thalamus (which acts as a relay station)
A second synapse takes place in the thalamus with a third order neuron
Third order neuron travels to the somatosensory cortex
DETECTS
Pain
Temp
Crude touch
Dorsal column/Medial lemniscal system
First order neuron enters the spinal cord and immediately travels up
In the upper spinal cord, the first order neuron synapses with the second order neuron, crossing to the contralateral side
Neuron continues to the thalamus where it synapses again to the third order neuron
Third order neuron travels to the somatosensory cortex
DETECTS
Fine touch
proprioception (muscle sense)
Vibration
List the somatotopic organization on the postcentral gyrus (somatosensory area), going from medial to lateral on the cortex. (homunculus)
Genitals
Foot
Leg
Back
Head
Arm
Forearm
Hand
Fingers
Thumb
Eye
Nose
Face
Lips
Tongue
Pharynx
Draw and label a picture of the visual system and the eye.
drawing should include: cornea lens iris fovea optic nerve retina
List the cell types in the retina and draw a diagram of their anatomical arrangement.
rod and cone cells
bipolar cell
amacrine cell
ganglion cell
List the functional characteristics of the rods
No axons, no APs
Generate receptor potentials
Release inhibitory neurotransmitter when relaxed/in the dark - light hyperpolarizes cells (shuts them off)
Function best in low light
One type photopigment (chemical sensitive to light)
- cannot detect color
Located: outside and around the fovea
cones functional characteristics
No axons, no APs
Generate receptor potentials
Release inhibitory neurotransmitter when relaxed/in the dark - light hyperpolarizes cells (shuts them off)
Function best in bright light
Detect detail
3 types, each with different photopigment and each sensitive to one primary color
Draw a flow diagram of the sequence of steps in the retina by which light is transduced to action potentials.
In the dark, rod and cone cells are depolarized, and they release an inhibitory neurotransmitter that shuts off the bipolar cells
When you turn on the light, the Na+ channels close. This causes hyperpolarization in the rod and cone cells (which means there is no inhibitory neurotransmitter stopping the bipolar cells from producing depolarizing
The bipolar cells depolarize. This makes a generator potential. If they depolarize enough, they depolarize the ganglion cells which produce an action potential.
List four types of eye movements, describe when they occur, and describe their overall function.
saccades
smooth pursuit
vestibular ocular reflexes
vergences
Draw a simple diagram of the auditory system.
should include external auditory canal tympanic membrane ear ossicles vestibular apparatus cochlea eustachian tube
cochlea and organ of corti
Cochlea – garden snail
3 compartments:
Vestibular duct/scala vestibuli
Cochlear duct
Scala tympani
Basilar membrane separates cochlear duct and tympanic duct, and contains organ of corti
Organ of Corti - where sound waves are converted to action potentials by hair cells
Hair cells are embedded in the tectorial; membrane
Sound waves make the basilar membrane vibrate
List three ways in which the outer and middle ear act to transmit pressure waves from air to fluid.
- Sound waves created by an external environmental stimuli (e.g., sound of car honking or a tree falling) travel through the air and reach the outer ear.
- Waves are funneled into the external auditory canal and strike the tympanic membrane, causing it to flex back and forth. This causes the small bones to vibrate in the oval window. The levering action of the ear ossicles amplifies the pressure waves that strike the tympanic membrane.
- Oval window is much smaller than the tympanic membrane, so the vibrations are amplified by 15-20x. The vibrations cause waves in the perilymph (fluid in the cochlea), which transmits a traveling wave to the hair cells along the basilar membrane.
- Hair cells detect vibrations and turn them into APs in the auditory nerve.
Describe how different frequencies of sound are transduced into action potentials.
Airwaves reach outer ear
Waves are funneled into the external canal
Waves strike ear drum (tympanic membrane)
The ear drum flexes back and forth
Ear ossicles amplify the pressure from the tympanic membrane
Amplified sound waves cause the oval window to vibrate
(SOUND IS FURTHER AMPLIFIED HERE since the oval window is much smaller than the ear drum) - reaches about 15 to 20 X original amount
Fluid inside the cochlea (perilymph) transmits waves to hair cells in the basilar membrane
Basilar membrane detects vibrations
Hair cells bend because of the basilar membrane’s vibrations
Ion channels open, hair cells depolarize
Depolarization causes a release of neurotransmitter from the hair cells
Neurons excited – action potentials produced
The louder the sound the stronger the vibration the more bent the chair cells the more NT released and higher frequency of action potentials produced
Signals reach the auditory cortex located in the temporal lobe of the brain
Short wave lengths (HIGH PITCH sounds)
displace the basilar membrane closer to the oval window
Narrow and thick
Tight
Stimulates hair cells at the bottom of the cochlea
Long wave lengths (LOW PITCH sounds)
displace the basilar membrane further from the oval window
Wide and thin
Loose
Stimulates hair cells at the top of the cochlea
NOTE: the hair cells also differ slightly
Draw a simple diagram of a single semicircular canal with hair cells and cupula and the utricle and saccule with otoliths.
…
List the major functions served by the vestibular system.
maintaining balance, equilibrium, and postural reflexes.
Name the movement detected by the semicircular canal receptors and the two detected by the otolith organs.
Semicircular canal receptors – rotational
Otolith organs – linear accelerations and decelerations and position if head when it is tilted
Otolith organs (utricle) - horizontal
Otolith organs (saccule) - vertical
State the four main functions of the cardiovascular system.
Transports o2 and nutrients in
Transports co2 out
Helps regulate pH and temp
Transports hormones and other subs around
