Overview of the PNS Flashcards
what are sensory axons in the limbs and body known as? [1]
where do sensory axons enter the spinal cord? [1]
where do motor axons leave the spinal cord? [1]
what are sensory axons in the limbs and body known as? [1]
sensory nerve fibres
where do sensory axons enter the spinal cord? [1]
dorsal root
where do motor axons leave the spinal cord? [1]
ventral root
what happens if the dorsal roots are severed between the dorsal root ganglion and spinal cord? [1]
what happens if the dorsal roots are severed between the dorsal root ganglion and spinal cord? [1]
sensory axons cannot regenerate into the spinal cord - creates paralysis
how can we tell whether loss of sensation is due to injury in spinal or nerve or dorsal root ganglion or a peripheral nerve? [2]
what can be a reason that a whole dermatome is damaged? [1]
how can we tell whether loss of sensation is due to injury in spinal nerve or dorsal root ganglion or a peripheral nerve? [2]
spinal nerve / dorsal root ganglion = whole dermatome affected
not a whole dermatome = damgae due to peripheral nerve
what can be a reason that a whole dermatome is damaged? [1]
fracture or slipped disc can crush a dorsal root ganglion
What is A, B & C? [3]
by which procedure do you collect CSF? [1]
at what vertebral level do you conduct ^? [1]
by which procedure do you collect CSF? [1]
lumbar puncture
at what vertebral level do you conduct ^? [1]
L3 or L4 (spinal cord stops at L1/2, so after this)
what is endoneurium?
what is endoneurium?
CT - thin protective membrane that surrounds individual or motor nerve fibres
what is perineurium?
CT - that wraps around fasicles of nerves
what is epineurium?
CT - the external connective-tissue sheath of a nerve trunk.
label A-D
what type of sensory receptors are present in body? [2] which responds to pain? [1]
what determines the kind of stimulus that sensory nerve endings will be sensitive to? [1]
what type of sensory receptors are present in body? which responds to pain? [1]
free nerve endings [1] = pain [1]
encapsulated nerve endings [1]
what determines the kind of stimulus that non-pain sensory nerve endings will be sensitive to? [1]
capsule surrounding the encapulated nerve ending
which of the following is Pacinian corpsucle?
A
B
C
D
E
which of the following is Pacinian corpsucle?
A
B
C
D
E
which of the following is Meissner corpuscle
A
B
C
D
E
which of the following is Meissner corpuscle
A
B
C
D
E
which of the following is a free nerve ending?
A
B
C
D
E
which of the following is a free nerve ending?
A
B
C
D
E
which of the following is a ruffini ending?
A
B
C
D
E
which of the following is a ruffini ending?
A
B
C
D
E
which of the following is a merkels disc?
A
B
C
D
E
which of the following is a merkels disc?
A
B
C
D
E
what causes, during development , the differentiated nerve fibre capsules? [1]
what causes, during development , the differentiated nerve fibre capsules? [1]
cytokines are released from the bare end of the nerve fibre and stimulate local CT to for a capsule around it
which of the following are rapidly-adapting, encapsulated neurons that responds to low-frequency vibrations and fine touch;
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are rapidly-adapting, encapsulated neurons that responds to low-frequency vibrations and fine touch;
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are are rapidly-adapting, deep receptors that respond to deep pressure and high-frequency vibration.
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are are rapidly-adapting, deep receptors that respond to deep pressure and high-frequency vibration.
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are slow-adapting, unencapsulated nerve endings that respond to light touch
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are slow-adapting, unencapsulated nerve endings that respond to light touch
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are slow adapting, encapsulated receptors that respond to skin stretch
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are slow adapting, encapsulated receptors that respond to skin stretch
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
how do sensory endings trigger APs? [4]
how do sensory endings trigger APs?
- *- special Na channels at their terminal membrane**
- **open when axon is bent & depolarise
- depolarisation is graded (not all or nothing):receptor potential**
- receptor potenital then triggers an AP futher at first node of Ranvier
intensity of an AP of a cutaneous stimulus is encoded by the WHAT of the AP in senosry axon? [1]
intensity of an AP of a cutaneous stimulus is encoded by the frequency of the AP in senosry axon? [1]
which of the following are:
- slow adapting? [2]
- fast adapting [2]
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
_which of the following are:
slow adapting? [2]_
Ruffini endings
Merkel’s disk
fast adapting [2]
Pacinian corpuscles
Meissner’s corpuscles
why are free nerve endings described as polymodal nociceptors?
why are free nerve endings described as polymodal nociceptors?
- *free nerve endings detect chemical stimuli as well as mechanical displacement**
- *v often produce sensation of pain**
what does information from hair receptors used to detect? [1]
what does information from hair receptors used to detect? [1]
light touch stimuli that moves across skin (e.g. someone stroking skin)
which of the following types of myelination would cause slow pain from the skin or act as thermoreceptors?
Aα
Aβ
Aγ
Aδ
C
which of the following types of myelination would cause slow pain from the skin or act as thermoreceptors?
Aα
Aβ
Aγ
Aδ
C
which of the following are used for general sensory afferents?
Aα
Aβ
Aγ
Aδ
C
which of the following are used for general sensory afferents?
Aα
Aβ
Aγ
Aδ
C
which of the following are used for motor to skeletal muscle?
Aα
Aβ
Aγ
Aδ
C
which of the following are used for motor to skeletal muscle?
Aα
Aβ
Aγ
Aδ
C
which of the following are used for fast pain from skin, muscle and joints?
Aα
Aβ
Aγ
Aδ
C
which of the following are used for fast pain from skin, muscle and joints?
Aα
Aβ
Aγ
Aδ
C
what is a receptive field? [1]
where do you find bigger receptive fields in the body? [1]
what is a receptive field? [1]
sensory nerve fibre bracnhes when it reaches the skin and supplies a small set of the same receptors in localised skin
where do you find bigger receptive fields in the body? [1]
larger on skin regions not used for tactile discrimination - e.g back
how does the brain precisely localise a sensory stimulus? [1]
what does this mean if get damage to a single senosry fibre? [1]
how does the brain precisely localise a sensory stimulus? [1]
receptive fields overlap [1]
what does this mean if get damage to a single senosry fibre? [1]
damage to a single fibre does not leave any region of skin anaesthetic
get less overlap
explain mechanism of what occurs after nerve injury xox
- peripheral nerve is cut
- schwann cell wraps around distal part to form continuous line of cells (and make a tunnel)
- proximal end: nerve fibres form growth cones: grow back down inside the sheath
- in growth cone, have filopodia, (contain actin)
- filopodia adhere to the cell adhesion molecules on inner surface of schwann cells, contract and pull forward along tunnel
- schwann cells wrap myeline around nerve fibre
- nerve fibres regen at 1.5mm/ day
