Peripheral Nervous System Flashcards
Sensory Function
Information coming into the CNS
Neurons can have 200,000 synapses from input fibers!
List different types of receptors and their stimuli.
mechanoreceptors : mechanical stimuli
electromagnetic : light
thermoreceptors : temperature chemoreceptors : chemicals
nociceptors : pain
mechanoreceptors
mechanical
electromagnetic
light
thermoreceptors
temperature
chemoreceptors
chemicals
nociceptors
pain
Receptor Potentials
Graded potentials
Stimulus causes change in membrane potential of receptor
EPSP or IPSP
If that receptor(graded) potential depolarizes to threshold, an AP will be sent to the CNS
Sensory Transduction
Transduce: to convert something into another form
In physiology, we are converting detected things (temperature, pain, light waves, etc.) into APs
APs are the only signals going into the CNS
Explain how sensory receptors transduce stimulus energy into electrical signal that can be used by the nervous system .
Graded potentials occur due to sensory receptor stimuli , causing a change in the membrane potential .
Sensory transduction is the process of converting sensory stimuli into APs , which are the only thing that travel to the CNS.
Explain how the CNS integrates sensory information to allow
perception.
perception is achieved through the combination of 4 concepts :
I. Modality principle :
different receptors detect and send signals for different types of stimuli
they send signals to different areas of the cerebral cortex
2. Location :
receptors throughout the body detect stimuli from different sections of the body
3. Intensity:
many APs in a row will send a more intense signal to CNS
4. Duration :
the duration of the AP will tell the CNS the duration of the stimulus
Modality/Labeled Line Principle
Different types of receptors are sensitive only to specific things
Those receptors send signals to specific areas of cerebral cortex
Location
Receptive fields for each area of body go to specific areas of cerebral cortex
Intensity
All APs are the same strength
In order to communicate a stronger signal,
more frequent APs are sent
Duration
Duration of AP tells CNS duration of stimulus (unless adaptation has occurred)
Adaptation
Receptors initially respond to stimulus
APs become less frequent
APs may stop completely
Describe sensory adaptation
Receptors will initially respond to a stimulus , but if there are continued stimuli that are not perceived as
dangerous or necessary , APs may slow or stop depending on the type of receptor.
ex.
feeling the clothes on your body
dorsal column (medial lemniscal) pathway
sends information to the brain regarding vibration ,
fine touch , and proprioception .
Sensory neurons in the body send signals to 1° cell body in the dorsal root ganglion , and the 2° neuron crosses the midline in the medulla
Anterolateral pathway
sends information to the brain regarding pain and coarse touch .
Sensory neurons
throughout the body send signals to the 1° cell body in the dorsal root gangIia of the spinal cord .
The 2° neuron
crosses the midline in the spinal cord,making this pathway faster.
Describe the primary motor pathway .
The primary motor pathway is the corticospinal tract , which carries signals from CNS to coordinate movement. The tract crosses over in the medulla.
Distinguish between innate and learned reflexes, monosynaptic and polysynaptic reflexes, and autonomic and motor reflexes.
Innate reflexes are apparent from birth while learned reflexes must develop.
Monosynaptic reflexes only involve 1 sensory neuron synapsing with 1
motor neuron , while polysynaptic reflexes may involve multiple or interneurons.
Autonomic reflexes are unconscious motor reflexes in organs or glands while
somatic reflexes involve skeletal muscle contraction.
Innate vs. learned
are apparent from birth while learned reflexes must develop.
Monosynaptic vs. polysynaptic
Monosynaptic reflexes only involve 1 sensory neuron synapsing with 1motor neuron ,
while polysynaptic reflexes may involve multiple or interneurons.
Somatic vs. autonomic
Autonomic reflexes are unconscious motor reflexes in organs or glands while
somatic reflexes involve skeletal muscle contraction.
Classification of Reflexes
Innate vs. learned
Monosynaptic vs. polysynaptic
Brain vs. spinal cord
Somatic vs. autonomic
Sympathetic Preganglionic axon
short
Sympathetic postganglionic axon
long
Sympathetic neurotransmitter
Ach and Norepinephrine
Sympathetic Receptors
Nicotinic (cholinergic ) and adrenergic
Sympathetic 2 Messenger
G Alpha Q, I, S
Sympathetic Target Tissues
Heart, intestines, pupil, bladder, genetalia, salivary glands
Parasympathetic preganglionic axon
Long
Parasympathetic postganglionic axon
Short
Parasympathetic neurotransmitter
Ach
Parasympathetic Receptors
Nicotinic and Muscarinic
Sympathetic Target Tissues
Heart, lungs, liver, pancreas, intestines, kidneys, bladder,
genetalia
Alpha 1 Receptor
coupled to G Alpha Q which activates PLC
Alpha 2 Receptor
coupled to G Alpha I which inhibits adenylyl cyclase
Beta 1
Beta 2
Beta 3
coupled to G Alpha S that activates adenylyl cyclase
Describe how the adrenal medulla works with the ANS
The adrenal medulla is a modified post -
ganglionic cell b/c it contains chromatin cells that secrete
epinephrine in response to a signal from the preganglionic neuron .
Explain how the ANS maintains homeostasis using
antagonistic control .
For certain organs of the body , the parasympathetic and sympathetic
nervous systems have opposing effects in order to maintain homeostasis.
Adrenal Medulla
Sympathetic pre-ganglionic neuron travels to adrenal medulla
Chromaffin cells
Modified post-ganglionic cells
Secrete epinephrine (and some norepinephrine)
Sympathetic pre-ganglionic neuron
travels to adrenal medulla
Chromaffin cells
Modified post-ganglionic cells
Secrete epinephrine (and some norepinephrine)
