lecture 6 - integrative systems Flashcards
sensation
conscious or subconscious awareness of internal or external stimuli
perception
conscious awareness and interpretation of a sensation
perception involves: (2)
cerebral cortex
precise localization and identification
stimuli our bodies are not aware of (examples)
x rays, Uv light
sensory modality
a specific type of sensation (2 classes)
2 classes of sensory modality
general sense
(somatic, visceral)
special senses
general somatic senses
tactile, thermal, pain, proprioceptive
general visceral senses
condition of internal organs
special senses
smell, taste, vision, hearing, equilibrium
only occur in certain areas of the body
major events of a sensation (4)
stimulation
transduction of stimulus
generation of nerve impulse
integration of input in CNS
which cortex area receives stimulus for touch?
primary somatosensory cortex
step 1 of the events of a sensation
stimulation of a receptor
stimulus must occur in receptive field
step 2 of the events of a sensation
transduction of stimulus to graded potential
stimuli converted into electrical energy
step 3 of the events of a sensation
generation a nerve impulse
only if graded potential reaches threshold
neurons that conduct impulses from PNS direction to CNS = first order neurons
first order neurons
neurones that conduct impulses from PNS directly to CNS
step 4 of the events in a sensation
integration of sensory input by the CNS
classification of sensory receptors (3)
microscopic structure
receptor location and activating stimuli
type of stimulus detected
classification of sensory receptors - micro structure (3)
free nerve endings or first order neurons
encapsulated endings of first order
separate cells
classification of sensory receptors - receptor location and activating stimuli (3)
exteroceptors
interoceptors
proprioceptors
classification of sensory receptors - type of stimulus detected (6)
mechanoreceptors
thermo
nocic
photo
cehmo
osmo
3 types of microstructure of receptors - free nerve endings
bare dendrites of first order neuron
pain temp tickle itch
stimulus generates graded potential
3 types of microstructure of receptors - encapsulated nerve endings
first order neurons dendrites enclosed in CT capsule
pressure vibration deep touch
stimulus generates graded potential
3 types of microstructure of receptors - separate sensory cells
specialized cells that respond to stimuli synapse with the first order neuron
vision taste hearing balance
stimulus generates graded potential in receptor cell, which releases NTs to first order neuron, which generates a graded postsynaptic potential
exteroceptors
located near surface of body (external)
hearing, vision, smell, taste, touch, pressure etc
interoceptors
location internally to monitor internal environment
usually subconscious besides pain
proprioceptors
located in muscles, tendons, joints, inner ear
sense Body position and movement, muscle length, and tension
mechanoreceptors
detect mechanical stimuli (anything that stretches or bends cells)
thermoreceptors
detect temperature change
nociceptors
detect tissue damage (pain due to physical or chemical damage
photoreceptors
detect light
chemoreceptors
detect chemicals
smell, taste, changes in body fluids
osmoreceptors
detect osmotic pressure in fluids
adaption in sensory receptors
tendency for receptor potential to decrease in amplitude in response to maintained constant stimulus
rapid adaptive receptors
smell, touch, vibration
specialized for detecting changes in environment
slowly adapting receptors
pain, position, chemical in blood
nerve impulses continue for duration of stimulus
4 modalities of somatic sense
tactile
thermal
pain
proprioceptive
types of tactile receptors (6)
tactile corpuscles
hair root plexuses
non encapsulated sensory corpuscles
bulbous corpuscles
lamellar corpuscles
itch and tickle receptors
tactile corpuscles
type of tactile receptor
touch, low freq vibrations
rapid adapting
hair root plexuses
type of tactile receptor
touch, movement on skin surface
rapid adapting
nonescapsulated sensory corpuscles
type of tactile receptor
continuous touch
slow adapting
bulbous corpuscles
type of tactile receptor
touch (stretching), pressure
slow adapting
lamellar corpuscles
type of tactile receptor
pressure, high freq vibration
slow and rapid adapting
itch and tickle receptors
type of tactile receptor
itch and tickle
słów and rapid adapting
tactile corpuscles location and appearance
located in dermal papillae
looks like a sperm
encapsulated
hair root plexus location and appearance
wrapped around hair follicles in hairy skin
obvious appearance
free nerve endings
nonencapsulated sensory corpuscles location and appearance
tree shaped
in dermal papillae - contact stratum basale
free nerve endings
bulbous corpuscles location and appearance
placenta lookin ass ones
in dermis/sublayer
encapsulated
pressure
sustained sensation felt over a larger area than touch
deeper deformation of skin
longer lasting and less intensity variation
sensed by lamellar corpuscles and bulbous corpuscles
lamellar corpuscles location and appearance
big ass ball onion things
located in dermis and sub layer
encapsulated
types of thermo receptors
warm and cold
thermoreceptors
2 types - warm and cold
free nerve endings
adapt rapidly at first, then slower
cold receptors activate between:
10-35 degrees C
warm receptors activate between:
35 -45 degrees C
nociceptors (in more detail)
free nerve endings
everywhere except the brain
types of pain
fast pain and slow pain
superficial somatic pain
deep somatic pain
visceral pain
fast pain
acute
- sharp
- occurs within 0.1 sec
- myelinated A nerve fibres
slow pain
chronic
- aching
- begins slower - less than 1 sec
- small, unmyelinated C nerve fibres
superficial somatic pain
stimulates pain receptors in the skin
deep somatic pain
stimulates receptors in skeletal muscle, joint etc
visceral pain
stimulates pain in visceral organs
AKA referred pain (usually felt in the skin overlying the organ, but can extend farther, due to skin being services by the same spinal cord segment)
largest area for referred pain
kidneys
types of proprioceptors (3)
muscle spindles
tendon organs
joint kinaesthetic receptors
muscle spindles
type of proprioceptor
deep in skeletal muscle
monitor length of muscle fibres
contains sensory neurons (free endings) and motor neurons
encapsulated by CT
neurones wrap 3-10 muscle fibres
tendon organs
type of proprioceptor
located at the junction of tendon and muscle to monitor tension
surrounded by CT capsule
joint kinaesthetic receptors
type of proprioceptor
found in articular capsules of synovial joints
detect joint position and movement
has bulbous/lamellar corpuscles and tendon organs for pressure, speed, and tension respectively
first order neuron
carries impulses from somatic receptors to the CNS
second order neuron
conducts impulses from CNS to thalamus
third order neurons
conduct impulses from thalamus to cortex
3 general pathways of somatic sensory impulses (how they ascend to cortex)
posterior column-medial lemniscus path
anterolateral (spinothalamic) path
trigeminothalamic pathway
posterior column medial lemnisus pathway sensations
touch, pressure, vibration, proprioception
from limbs, trunk, neck, posterior head region
posterior column medial lemnisus pathway first order neuron axon and cell body
axon - enters spinal cord, goes to medulla in posterior tract
body - posterior root ganglion
posterior column medial lemnisus pathway second order neuron axon and cell body
axon - ascends as medial lemniscus tract to thalamus
body - in medulla nuclei
posterior column medial lemnisus pathway decussation point
medulla
posterior column medial lemnisus pathway third order neuron axon and cell body
axon - extends from thalamus to primary somatosensory area
body - in thalamus
anterolateral (spinothalamic) pathway sensations
pain, temp, touch, pressure
from limbs, trunk, neck, posterior head
anterolateral (spinothalamic) pathway first order neuron axon and cell body
axon - synapses in spinal cord
body - posterior root ganglion
anterolateral (spinothalamic) pathway second order neuron axon and cell body
axon - goes to thalamus from spinal cord as spinothalamic tract
body - in posterior grey horn
anterolateral (spinothalamic) pathway third order neuron axon and cell body
axon - goes from thalamus to primary somatosensory area
body - in thalamus
anterolateral (spinothalamic) pathway decussation point
spinal cord
from posterior grey horn across grey commissure to spinothalamic tract
spinothalamic tract location in spinal cord
anterior from corners
trigeminothalamic pathway sensations
most somatic sensations from the face
touch, temp, pain etc
trigeminothalamic pathway first order neuron axon and cell body
axon - goes to pons or medulla
body - posterior root ganglion
trigeminothalamic pathway second order neuron axon and cell body
axon - go to thalamus as trigeminothalamic tract
body - medulla or pons
trigeminothalamic pathway third order neuron axon and cell body
axon - goes to primary somatosensory area
body - in thalamus
trigeminothalamic pathway decussation point
pons or medulla
which sensory pathway is for vibration in the trunk?
posterior column medial lemniscus
which sensory pathway is for pain in the body
anterolateral (spinothalamic)
which sensory pathway is for temp in the face?
trigeminothalamic
thalamus
sorts of filters into according to the areas the body sensations are coming from
why do axon collaterals of somatic sensory neurons also carry signals to the cerebellum
essential for posture, balance, and coordination
these senses are not consciously perceived
major routes for signals to reach cerebellum (2)
do these tracts decussate
anterior and posterior spinocerebellar tract
these tracts do not decussate
2 neurons involved in somatic motor pathways
upper motor and lower motor (UMN and LMN)
upper motor neurons facts (3)
technically an interneuron
cell Body in CNS motor area
axon mostly in cortex
lower motor neuron facts
extends from brainstem or spinal cord to skeletal muscles
known as the final common pathway
cell body in lower parts of CNS
pathways of LMNs in head and body
head
brainstem -> cranial nerves -> skeletal muscle
body
spinal cord -> spinal nerves -> skeletal muscle
4 neural circuits that control movement by providing input to lower motor neurons (somatic motor pathways)
basically what 4 neurons connects to LMNs
local circuit neurons
upper motor neurons
corpus striatum neurons
cerebellar neurons
two types of upper motor neuron pathways
direct (pyramidal) pathways
indirect pathways
direct motor neuron pathways
provide input to LMNs via axons that come directly from cerebral cortex
follow corticospinal (lateral /anterior ) or corticobulbar tracts
direct, hence the name
indirect motor neuron pathways
provide input to lower motor neurons from motor centres in the brainstem
extra steps basically
could go from motor cortex to corpus striatum to brainstem to LMNs, lots of pathways that are just not direct
control of body movement involves: (3)
cerebral cortex
corpus striatum
cerebellum
how does the cerebral Cortex control body movement?
premotor and primary motor cortexes
initiate and control precise movements
how does the corpus striatum control body movement?
help establish muscle tone and initiate and terminate movements
how does the cerebellum control body movement?
helps make movements smooth, maintain posture and balance
primary motor cortex location
in pre central gyrus of frontal lobe
premotor area function
creates “motor plan”
receives input from association areas via corpus striatum
lateral corticospinal tract movements
distal part of limbs, hands, feet
skilled movements
lateral corticospinal tract pathways steps (4)
primary motor cortex
cerebral peduncle
medulla (decussates in pyramids)
descends in lateral white funiculi
lateral corticospinal tract synapses with _____ at _______
synapses with local circuit neurons or LMNs in the anterior grey horn
anterior corticospinal tract movements
trunk and proximal parts of limbs
anterior corticospinal tract pathway steps (4)
primary motor cortex
cerebral peduncle
pyramids of medulla
descends in anterior white funiculi
lateral corticospinal tract decussation point
pyramid of medulla
anterior corticospinal tract decussation point
in anterior white commissure, just before synapsing with LMN/local circuit neurons in anterior grey horn
anterior corticospinal tract synapses with _____- at ______
local circuit neurons or LMNs in anterior grey horn
corticobulbar tract movements
skeletal muscles in the head
eyes, tongue, neck, expression, mastication etc
corticobulbar tract pathway steps (3)
primary motor cortex
cerebral peduncle
brainstem
corticobulbar tract decussation point
some fibres decussate, others done (50%?)
in medulla/pons/midbrain
corticobulbar tract synapses with ______ at ______
axons of UMNs terminate in nuclei of all motor or mixed cranial nerves (all but 1,,2, 8)
anterior corticospinal tract - what does this tract look like in the spinal cord?
really smalll tract, on either side of the anterior median fissure
lateral corticospinal tract - what does this tract look like in the spinal cord?
big tract, lateral sides of cord, posterior half of the lateral funiculi
indirect pathway facts (
all motor pathways other Thant the corticospinal and corticobulbar tracts
axons from UMNs descend into 5 major tracts
synapse with local circuit neurons or LMNs
mostly control involuntary movement
indirect pathways (just names, no detail, 5)
vestibulospinal
lateral and medial reticulospinal
tectospinal
rubrospinal
connections of the corpus striatum (
receive info from: sensory, motor, association cortexes
outputs info to: thalamus, motor centres in brainstem
corpus striatum regulates: (3)
movement initiation and termination
muscle tone
non motor processes (memory, attention)
parkinsons disease have a degeneration of what?
dopamine releasing neurons that extend from substantial nigra to corpus striatum
huntingtons disease facts (
inherited disorder
degeneration putamen and caudate nucleus (nuclei in corpus striatum)
loss of neurons that makes AcH
4 aspects of cerebellar function
monitor intentions for movement
monitor actual movement
compare intention with performance
send out corrective feedback
ex. serving a vball, intending on getting it in. action is carried out, balll goes too far. feedback sent out to hit it lighter
cerebellum receives input about proprioception from
spinocerebellar tract
cerebellum receives input about vestibular sensation from
vestibular nuclei
cerebellum receives input about visual info from
superior colliculi
why is a reflex faster than a voluntary movement?
less steps, in short
reflex:
- receptor
- sensory neuron
- interneuron
- motor neuron
- effector
voluntary movement:
- receptor
- spinal neuron
- thalamic neuron
- cortical neuron
- interneuron
- UMN
- LMN
- effector
indirect pathways are all motor pathways other that:
corticobulbar and corticospinal pathways
indirect pathways (5)
vestibulospinal
lateral/medial reticulospinal
tectospinal
rubrospinal
vestibulospinal pathways
indirect
from vestibular nucleus
maintain posture and balance
involuntary
lateral and medial reticulospinal pathways
indirect
from reticular formation
facilitate flexor/extensor reflexes
muscle tone
medial excites, lateral inhibits
lateral and medial reticulospinal pathways - whihc excites and whihc inhibits?
medial excites, lateral inhibits
tectospinal pathway
from superior colliculi
moves head, eyes, and trunk in response to visual stimuli
rubrospinal pathway
from red nucelus
precise movements of upper limbs
