Week 1 Flashcards

Question

receptors for temperature, pain, itch, Pressure/touch, Position sense:

Answer 1

- temperature: Thermoreceptors - pain: Nociceptors - itch: Chemoreceptors - Pressure/touch: mechanoreceptors (respond to distortions in skin eg. phone vibration) - Position sense: Proprioceptors (obstacle while walking, we can avoid it by moving our legs without looking down)

Answer 2

All modalities other than seeing, hearing, tasting, smelling, and vestibular balance. يعني يكون شي عام and they are scattered all over the body

Answer 3

- transduction: encoding of stimuli into electrical signals (translation) - transmission propagation of this electric signals to CNS

Answer 4

if a receptor is more selective (specific) for a single stimulus energy – its adequate stimulus. Differential sensitivity: receptors have a LOW threshold for the adequate stimulus, and a HIGH or no threshold at all to others (inadequate stimuli) Ex: photo receptors are activated by light, that is their adequate stimulus. When you’re being hit on the eye, you can also see light and this is because the high intensity of the stimulus causes the activation of the photo receptors, that would be the inadequate stimuli.

Answer 5

Change in membrane potential because of a stimuli that allowed ions to diffuse through channels if stimulus is strong, receptor potential reaches AP threshold, AP is generated

Answer 6

increases in the frequency of AP

Answer 7

The receptor

Answer 8

- aka dynamic receptors - alert us to CHANGES in sensory stimuli - responsible for our ability to cease paying attention to constant stimuli (aka sensory adaptation) - like wearing a ring, you only feel the pressure when you put it on (put stimuli) and take it off (stimuli removed which causes another receptor potential) - it's RAPID adaptation - Pacinian’s corpuscle, Meissner’s corpuscle

Answer 9

- aka static receptors - SLOW adaptation - don't disappear but decrease with time, it only disappears when you remove the stimuli (Generate AP throughout, but diminish slowly. Give continuous info about stimulus) - Imp for when receptors tell you about muscle movements. Eg: when writing, how your finger is continuously moving with movements. If it was the same position for a while, (static) then AP firing could decrease - Proprioceptors, nociceptors, merkel cells

Answer 10

- Tonic receptors (static receptor) - eg. some Nociceptors - Imp because you want to constantly know that there’s something damaging to the brain (you don’t want to forget about it)

Answer 11

- Respond to distortion of the membrane eg. stretch - eg. lining of the stomach when full or bladder distention or lung inflation - pressure (membrane stretching) cause opening of NA+ channels causing generator/ receptor potential - Direct pressure on skin and/or high-frequency vibration detected by Pacinian corpuscles.

Answer 12

- Direct: stretching the channel itself OR through structural proteins that are part of the channel (intra or extra cellular proteins) - Indirect: through membrane structural proteins (protein is NOT related to channel eg. 2nd messengers)

Answer 13

Markel receptor: - Sustained touch, texture, pressure - sense a touch that lasts longer - SLOW adaptation - eg. Braille (blind people text) - superficial in glabrous skin (skin that doesn't have hair)

Answer 14

Meissner Corpuscle: - Changes in light touch, stroke, Flutter hence -> - FAST adapting - superficial in glabrous skin (skin that doesn't have hair)

Answer 15

Pacinian Corpuscle: | - FAST adapting

Answer 16

Ruffini Ending: - skin stretch, sustained pressure - eg. when holding a big object, your hands are being stretched, collagen fibers will stretch, cause afferent that will let your brain know that you’re holding something thats stretching your hand - SLOW adapting

Answer 17

Hair follicle: - flutter, light touch - in hairy skin unlike meissner corpuscle - eg. when wind blow on your skin - FAST adapting

Answer 18

Proprioception = position sense 1. with eyes closed know wether you're moving their fingers/ toes up or down 2. Romberg test: with eyes closed, if their proprioception is not intact, then they will sway, and when they open their eyes, the swaying will stop because vision compensates for proprioceptive loss.

Answer 19

stimulated by stretch > fibers elongate > sensed by nerve endings A1 and II (2) > fire AP

Answer 20

- Gamma motor: control spindle sensitivity - alpha motor: muscle contraction of skeletal muscles

Answer 21

- in Golgi tendon organ - it signals muscle tension to CNS - the axon of 1b is intertwined with the collagen fascicles - When the Golgi tendon organ is stretched (usually because of contraction of the muscle), the Ib afferent axon is compressed by collagen fibers and its rate of firing increases.

Answer 22

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For visceral sensations: - PO2 , PCO2 receptors - Hunger: food molecules activate hypothalamic chemoreceptors - Thirst: osmoreceptors ``` For pain: - Lactic acid when exercising open H+ gated ion channels on nociceptive neural endings For itch: - histamine

Answer 23

Transient receptor potential channel (TRP) each one has different sensitivity: - TRPV3 in chilli - TRPV4 in chilli (for both, Adequate stimuli: temperature inadequate stimuli: vanilloid in chilli) - TRPM8 in menthol (nonselective cation channel expressed in small diameter trigeminal and dorsal root ganglion neurons in which cooling and menthol evoke inward depolarizing currents and intracellular calcium rises

Answer 24

- For pain - FREE nerve endings respond to stimuli and damaged tissue Three types: 1. Thermal nociceptors 2. Mechanical nociceptors 3. polymodal nociception

Answer 25

High intensity mechanical, chemical or thermal (v. hot or v. cold) stimuli UNMYELINATED C axons that conduct more SLOWLY (dull, burning pain, diffusely localised, poorly tolerated). ``` TRPA1 TRPV1 TRPV2 MS ASIC (for acid accumulation)

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Answer 26

ntense pressure to skin thinly myelinated axons stabbing, squeezing, pinching

Answer 27

activated by extreme temp (v. high or v. low) in peripheral endings of small diameter, thinly myelinated

Answer 28

big in diameter and myelinated

Answer 29

myelinated: Proprioception and mechanoreceptors NONmyelinated: nociceptors, thermoreceptors

Answer 30

- Decreased (flaccidity) - weakness and w time there will be muscle atrophy - Hyporeflexia (decreased reflex) - Hypotonia (decreased muscle resistance to passive movement) - Fasciculations (muscle contraction seen as skin flickering but not strong enough to move the limb) - found in Ant horn cell - eg. Polyneuropathy, (GBS) gullian barre syndrome - flexors and extensors equally affected - caused by: 1- Poliomyelitis 2- Spinal muscular atrophy 3- Amyotrophic lateral sclerosis (ALS)

Answer 31

- Increased tone (spasticity) - Hypertonia - hypereflexia - Above anterior horn cell in spinal cord - eg. stroke, multiple sclerosis - Early UMNL manifest as LMNL ( you don't get stroke right away when there is an UMNL) - extensors are weaker in UPPER limbs (triceps) - flexors are weaker in LOWER limbs - +ve babkinski - +ve clonus - +ve hoffman sign - superficial (abdominal reflexes) are absent (decrease)

Answer 32

- Caused by Polio virus causing anterior horn cells destruction - mostly asymptomatic - few have LMN picture - Diagnosis: RNA of virus in CSF

Answer 33

- Caused by genetics (autosomal recessive) - progressive weakness &amp; atrophy of muscles - Treated by Antisense oligonucleotide

Answer 34

- stephen hawking! - It's progressive, pattern of weakness affects right arm then left arm then left leg then right leg - Affects motor neurons in cerebral cortex and brain stem (UMNL) as well as anterior horn of spinal cord (LMNL)

Answer 35

- Neuron-opathy = dorsal root ganglion - Plexopathy = plexus - Motor neuron disease = cell body in anterior horn - Radiculopathy = Root - Peripheral neuropathy = peripheral nerve

Answer 36

- Degeneration of dorsal root ganglia &amp; projections - Diseases affecting the neuron cell body Divides to: - Motor neuron disease (anterior horn affected) - Sensory neuronopathy - Ganglionopthy - eg. herpes zoster (shingles)

Answer 37

- affects spinal nerve ROOT - classic presentation is pain, if in the neck it's brachial plexus, or in lower back and goes to lower limbs - weakness in muscles supplied by that root - radiating pain along the root dermatome - DECREASED deep tendon reflex (eg. knee jerk reflex) in corresponding root ONLY - caused by compression eg. herniated disc (nerve root compressed, muscles supplied by that root damaged

Answer 38

- affects plexus (Brachial or Lumbosacra) - affects sensory and motor (shows both symptoms) - weakness and numbness - Caused MOSTly by diabetes mellitus, can be caused by focal mass (pancoast tumor, a lung tumor that affects brachial plexus) - eg. Hornor's syndrome, happens bcz of disturbtion of brachial plexus (C8 - T1)

Answer 39

- Causes are either Hereditary or Acquired - Hereditary -> Charcot marie tooth disease (IMPORTANT) - Acquired (MINI-P): Metabolic or medication (diabetes, vit B12 def., chemotherapy) Immune Neoplastic Infections Physical (compression)

Answer 40

- one peripheral nerve affected - cranial or spinal nerve - caused by trauma, compression or entrapment - loss of function in part supplied (motor, sensory, &amp;/or autonomic) - eg. spinal nerve example, Carpal tunnel syndrome -> numbness in lateral 31⁄2 digits +/- weakness -> examined by phalen sign and tinel sign - eg. Cranial nerve 7 -> bell's palsy -> weakness in face muscle, muscle not moving - treated w/ NSAID, steroids, surgery

Answer 41

- Symmetric - Length dependent - Long fibers affected first (leg fibers first) - Starts at the toes and continues going up until it reaches the hands - example: patient came w/ numbness that started in feet (both sides) toothpicks then started to go to ankles then in both hands

Answer 42

- More than one peripheral nerve affected at the same time or one after the other - ASYMMETRIC - affect cranial or spinal n. - examples: 1. Vasculitis of vasa nervorum 2. Sarcoidosis 3. Diabetes mellitus - Symptoms are motor (weakness) (LMNL features) and sensory (numbness is most imp) divides to Demyelinating and Axonal neuropathy

Answer 43

- they're both divisions of Polyneuropathy 1. Demyelinating neuropathy: - loss of myelin so signal will be slower - causes: common in DIABETES MELLITUS 2. Axonal neuropathy: - damage occurs to axon itself so signal is not able to pass at all - causes: Guillain-Barre syndrome (GBS) + mostly autoimmune

Answer 44

3. Amyotrophic lateral sclerosis ALS, cause it's mixed

Answer 45

3. Hyperreflexia with spasticity cause it doesn't happen that early (2 hrs) remember that early UMNL manifests as LMNL

Answer 46

2. positive hoffman's sign it's an UMNL sign and Note: Down-going toes on plantar reflex is a normal response so it's present even in carpal tunnel syndrome

Answer 47

1. Filum terminale | 2. Denticulate ligament

Answer 48

- it's an enlargement in the subrachnoid mater - contains 3 things: 1) CSF 2) cauda equina 3) filum terminale - we aspirate CSF from here to avoid injuring the spinal cord

Answer 49

- Ends with arachnoid at the 2nd sacral vertebrae - extradural space which separates the spinal cord from the vertebra so it's not attached

Answer 50

innervate most of the body and form the brachial and lumbosacral plexus

Answer 51

visceral motor

Answer 52

gives rise to "pre-ganglionic sympathetic fibers."

Answer 53

gives rise to "pre-ganglionic parasympathetic fibers."

Answer 54

Posterior column: 1) Fasculus gracilis 2) Fasculus cuneatus Anterior column: Spinothalamic tract ``` Lateral column: spinothalamic Posterior spinocerebellar Anterior spinocerebellar Spinotectal Spinoreticular Posterolateral (Lissauer’s)

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Answer 55

Lateral column: Lateral corticospinal Rubrospinal Lateral reticulospinal ``` Anterior: Anterior corticospinal Tectospinal Vestibulospinal Medial Reticulospinal

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Answer 56

Dorsal root ganglia

Answer 57

Ventroposterior Lateral (VPL) nucleus of thalamus (then it goes to somatosensory cortex)

Answer 58

Lamina 1 AND 5 only

Answer 59

amina 1 TO 5 (1,2,3,4,5)

Answer 60

Anterolateral pathway 1st order neuron Origin: DRG End: lamina I to V (dorsal root horn) Do one of two things: 1. Terminate at that segment level and synapse with the 2nd order neuron level 2. Join the Lissauer’ tract (posterolateral tract), which will either ascend or descend 1 to 3 segment levels. Then it will terminate and synapse with the 2nd order neuron. Function: - Pain (sharp, prickling and well organized) - Pressure - Temperature

Answer 61

Origin: lamina I and V (dorsal root horn) End: VPL of the thalamus The neuron body of the 2nd order neuron is at either the I OR V lamina. The axon crosses the spinal cord at the anterior commissure, causing the tract to be contralateral. The axon ascends the spinal cord at the anterolateral fasciculus of the white matter. It will terminate at the VPL of the Thalamus.

Answer 62

Origin: VPL of the thalamus | End: Primary somatosensory cortex

Answer 63

Lateral pathway Origin: DRG End: lamina I and V (dorsal horn) Function: - Controls pain - Spinovisual reflex: it brings about the movement of the eyes and head towards the source of information

Answer 64

Origin: lamina I and V (dorsal horn) End: Superior colliculus The neuron body of the 2nd order neuron is at either the I or V lamina. The axon crosses the spinal cord, causing the tract to be contralateral. The axon ascends the spinal cord at the lateral fasciculus of the white matter. It will terminate at the superior colliculus.

Answer 65

Lateral pathway Origin: DRG End: lamina VI, VII, and VIII (6, 7, 8,) (dorsal horn) Function: - Pain (dull, aching, and poorly localized) - Influence the level of consciousness

Answer 66

Origin: lamina VI, VII, and VIII (dorsal horn) End: reticular formulation of brain stem and intralaminar nuclei of thalamus The neuron body of the 2nd order neuron is at either the VI, VII, or VIII lamina. The axon does not cross the spinal cord, causing the tract to be ipsilateral. The axon ascends the spinal cord at the lateral fasciculus of the white matter. It will give multiple synapse. It synapses contralaterally (it crosses) to the reticular formation of the brain stem, while the axon continues upwards and terminates at the intralaminar nuclei of the thalamus at the same side (ipsilateral).

Answer 67

Lateral pathway Origin: DRG End: dorsal horn ``` Function: Visceral information (ex. distended stomach)

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Answer 68

Origin: dorsal horn End: VPL The neuron body of the 2nd order neuron is at dorsal root horn. The axon travels with the spinothalamic tract. The axon crosses the spinal cord at the anterior commissure, causing the tract to be contralateral. The axon ascends the spinal cord at the anterolateral fasciculus of the white matter. It will terminate at the VPL of the Thalamus.

Answer 69

Origin: VPL | End: somatosensory cortex

Answer 70

Spinocerebellar pathway (found laterally) Origin: DRG at T1 to L1 or2 (UP) End: Clark’s nucleus (nucleus dorsalis) found at T1 to L1 or 2 Function: Unconscious proprioception

Answer 71

Origin: Clark’s nucleus (nucleus dorsalis) found at T1 to L1/2 End: cerebellum The neuron body of the 2 order neuron is at Clark’s nucleus (nucleus dorsalis) found at T1 to L1/2. The axon travels upwards and passes through the inferior cerebellar peduncle to terminate at the cerebellum.

Answer 72

Spinocerebellar pathway (found laterally) Origin: DRG at T12 to L5 (DOWN) End: Spinal border neurons found at T12 -L5 Function: Unconscious proprioception

Answer 73

Origin: Spinal border neurons found at T12 -L5 End: cerebellum The neuron body of the 2nd order neuron is spinal border neurons found at T12 -L5. The axon crosses the spinal cord, causing the tract to be contralateral. The axon ascends the spinal cord at the lateral fasciculus of the white matter. It then recrosses in the middle cerebellar peduncle, causing the tract to be ipsilateral. It will terminate at the cerebellum.

Answer 74

Spinocerebellar pathway (found laterally) Origin: lateral cutaneous (accessory pathway) End: cerebellum The neuron body is found in the lateral cutaneous nucleus in the medulla. This pathway is an accessory pathway as it begins at the middle of another pathway. The axon travels through the inferior cerebellar peduncle to terminate at the cerebellum. Function: Unconscious proprioception

Answer 75

Spinocerebellar pathway (found laterally) Origin: DRG End: dorsal horn Function: Proprioception (the information conveyed is from cutaneous and proprioceptive organs)

Answer 76

Origin: dorsal horn End: inferior olivary nucleus The neuron body of the 2nd order neuron is at the dorsal horn. The axon crosses the spinal cord at the commissure, causing the tract to be contralateral. The axon ascends the spinal cord at the lateral fasciculus of the white matter. It will terminate at the inferior olivary nucleus.

Answer 77

Origin: inferior olivary tract End: cerebellum The neuron body of the 3rd order neuron is at the inferior olivary tract. The axon crosses the inferior cerebellar peduncle (the crossing then recrossing causes the pathway to become ipsilateral) and terminates at the cerebellum

Answer 78

Origin: DRG End: gracilis nucleus in medulla The neuron body is found in the DRG. The central branch of the axon will ascend the spinal cord until it terminates at the gracilis nucleus in the medulla. Function: (important) info from below T6 Conscious proprioception Discriminative touch Vibration Joint movement

Answer 79

Origin: gracilis nucleus in medulla End: VPL The neuron body is at the posterior medulla in the gracilis nucleus. The axon will cross to the other side of the medulla (contralateral) and terminate at the VPL of the thalamus.

Answer 80

Origin: VPL | End: somatosensory cortex

Answer 81

Function: (important) info from above T6 Conscious proprioception Discriminative touch Vibration Joint movement

Answer 82

Origin: cuneatus nucleus in medulla End: VPL The neuron body is at the posterior medulla in the cuneatus nucleus. The axon will cross to the other side of the medulla (contralateral) and terminate at the VPL of the thalamus.

Answer 83

Origin: VPL | End: somatosensory cortex

Answer 84

Origin (multiple): 1/3 primary cortex, 1/3 supplementary cortex, and 1/3 somatosensory cortex End: anterior horn or interneurons The tract begins in the cerebral cortex (1/3 primary cortex, 1/3 supplementary cortex, and 1/3 somatosensory cortex) and descends to the brain through the cerebral peduncle, then to the Pons (where fibers will move around within the Transverse pontine nucleus). Here the tract divides. The fibers will descend to the medulla into the pyramid WITHOUT CROSSING (15%); these will form the anterior corticospinal tract, which will travel downwards, and few will cross at spinal segments. The fibers terminate at any segment level at the medial group of the anterior horn. Some will synapse with lower motor neurons (3rd order neurons), while others will synapse with interneurons (2nd order neurons). Function: Voluntary control of axial muscles If injured: Injury to any side of the anterior corticospinal tract does not affect muscle innervations because the supply to muscles is bilateral

Answer 85

Origin (multiple): 1/3 primary cortex, 1/3 supplementary cortex, and 1/3 somatosensory cortex End: anterior horn or interneurons The tract begins in the cerebral cortex (1/3 primary cortex, 1/3 supplementary cortex, and 1/3 somatosensory cortex) and descends to the brain through the cerebral peduncle, then to the Pons ( where fibers will move around within the Transverse pontine nucleus). Here the tract divides. The fibers will descend to the medulla into the pyramid and CROSS (85% will undergo decussation at medulla); these will form the lateral corticospinal tract, which will travel laterally and downwards. The fibers terminate at any segment level at the lateral group of the anterior horn. Some will synapse with lower motor neurons (3rd order neurons), while others will synapse with interneurons (2nd order neurons). Function: Voluntary control of distal muscles If injured: 1. Injury of the tract (after decussation/ after medulla) will cause ipsilateral deficiency of innervation to the muscles innervated by the tract. Ex. Lesion to left lateral column of spinal cord -> left side of body is paralyzed 2. Injury in the brain (before decussation/ before medulla) will cause contralateral deficiency of innervation to the muscles innervated by that tract. Ex. Lesion to right hemisphere -> left side of body is paralyzed The lateral corticospinal tract is closely related to the rubrospinal tract, so injury in that area will probably affect both tracts

Answer 86

Responsible for voluntary control of face and body muscles

Answer 87

responsible for involuntary control + balance + posture

Answer 88

Origin: medial vestibular nucleus in medulla End: anterior horn of cervical segments The tract begins at medial vestibular nucleus in medulla and travels through the medial longitudinal fasciculus (fibers which control extra ocular muscle) and terminates at the ventral horn of cervical segments. Some will synapse with lower motor neurons (3rd order neurons), while others will synapse with interneurons (2nd order neurons). Function: Stabilizing head movement Coordinating head movement with eye movement. Ex. When looking up, we move our neck up as well Innervates muscles of head and neck If injured: Injury to any side of the medial vestibulospinal tract does not affect muscle innervations because the supply to muscles is bilateral

Answer 89

Origin: lateral vestibular nucleus in medulla End: anterior horn The tract begins at medial vestibular nucleus in medulla and travels through the lateral fasciculus and terminates at the ventral horn. Some will synapse with lower motor neurons (3rd order neurons), while others will synapse with interneurons (2nd order neurons). ``` Function: Balance Postural changes to compensate for tilts and movements of the body Increase activity of extensor muscles Decrease activity of flexor muscles ``` If injured: Injury of the tract will cause ipsilateral deficiency of innervation to the muscles innervated by the tract. Ex. Lesion to left lateral column of spinal cord -> left side of body is affected

Answer 90

Origin: red nucleus End: anterior horn, synapsing with the lateral motor neurons Tract begin at red nucleus (found in midbrain). It CROSSES the midbrain and runs laterally with the lateral corticospinal tract and ends at the lateral group of the anterior horn. Some will synapse with lower motor neurons (3rd order neurons), while others will synapse with interneurons (2nd order neurons). Function: Activate flexor muscle If injured: Injury in the tract will cause contralateral deficiency of innervation to the muscles innervated by that tract. Ex. Lesion to right fasciculus -> left side of body is affected

Answer 91

Origin: superior colliculus End: anterior horn at cervical level of spinal cord The tract begins at superior colliculus (receives input from optic nerve). The axon descends and crosses in midbrain. They enter spinal cord and they will terminate at the cervical level Function: Reflex Turning head in response to visual stimulus

Answer 92

Pontine Origin: pontine reticular formation (brainstem) End: anterior horn or interneurons Function: Walking, running Activate extensor muscles

Answer 93

medullary Origin: medullary reticular formation End: anterior horn or interneuron Function: Walking, running Activates flexor muscles

Answer 94

- Lateral: control distal limb muscles - Medial: (always bilateral) controls axial/proximal muscles

Answer 95

they are upper motor neurons UMN, they come from the brain. (All the tracts mentioned previously are part of the third order neurons which are lower motor neurons and they send signals directly to the muscles)

Answer 96

- Control visceral activities - UMN: o Origin: cerebral cortex, hypothalamus, amygdala, reticular formation o End: lateral horn at T1-L1/2 and S2-S2 o Pathway: originates from cerebral cortex, hypothalamus, amygdala, reticular formation. The axons descend and CROSS at the midbrain. They continue down to the lateral horns in the thoracic or sacral segments. ▪ In thoracic region, the lateral horn in the spinal cord gives rise to preganglionic sympathetic fibers ▪ In sacral region, the lateral horn in the spinal cord gives rise to preganglionic PARAsympathetic fibers

Answer 97

- Sense Muscle tension

Answer 98

- Sense Muscle length (static gamma) - Sense Muscle rate/ speed (dynamic gamma) - has three parts: 1. Specialized intrafusal muscle fibers: contain non-contractile region 2. Sensory fibers (Ia, most myelinated) that terminate in non-contractile region of the intrafusal fibers. - > When the muscle is stretched, the distance between the spirals will increase which will increase the activity of Ia fibers. 3. Motor axons (gamma)

Answer 99

- Motor: gamma alpha - Sensory: Ia (1a) II (2)

Answer 100

1. Alpha: Aα - Extrafusal innervation Large diameter axons = fast transmission 2. Gamma: γ - Innervates the core of muscle spindle - Intrafusal innervation - two types, dynamic and static - Modulate sensory information in a dynamic or static fashion

Answer 101

1. Nuclear chain fibers 2. Nuclear bag neurons

Answer 102

1. Nuclear chain fibers: innervated by static γ motor neurons only. 2. Nuclear bag neurons: innervated by both static and dynamic γ motor neurons.

Answer 103

Extrafusal fibers are innervated by α motoneurons, generate force. Intrafusal fibers are innervated by γ motoneurons, adjust sensitivity of muscle spindle

Answer 104

- stretch reflex -> monosynaptic - reciprocal inhibition -> polysynaptic

Answer 105

- enhances the effect of the active pathway - suppressing the activity of other, opposing, pathways. - Activates one pathway and inhibits all the lateral pathways. - Example: knee jerk reflex.

Answer 106

- stops the activity within the stimulated pathway and prevents it from exceeding a certain critical maximum. - Inhibits the same Pathway. - Example: autogenic reflex. - Renshaw cells are inhibitory cells that transmit inhibitory signals to the surrounding motor neurons.

Answer 107

- stepping on sharp object - receptor is on the skin (not inside the muscle) - polysynaptic - occurs in response to a tactile, painful, or noxious stimulus. Somatosensory and pain afferent fibers initiate a flexion reflex that causes withdrawal of the affected part of the body from the painful or noxious stimulus. - reflex produces flexion on the ipsilateral side & extension on the contralateral side (extensor muscles will contract and flexor muscles relaxes). Extension on the contralateral side is called crossed-extension reflex.

Answer 108

1. anterior spinal artery for ant. 2/3 2. posterior spinal arteries for post. 1/3 3. great anterior medullary artery of adamkiewicz (from left side of aorta) supplies LOWER part of the spinal cord (IMPORTANT)

Answer 109

Dorsal root ganglia

Answer 110

Wallerian Degeneration: myelin AND axon will be destroyed HOWEVER Connective tissue especially (endoneurium) AND schwann cells will persist

Answer 111

- Clean/ digest the debris in Wallerian Degeneration - promotes angiogenesis - type 2 machrophage will produce factors for the regeneration process

Answer 112

INJURED: - chromatolysis: Nissl material becomes less in number, fine, granular, dispersed throughout the cytoplasm - nucleus moves towards the periphery (eccentric nucleus) - cell body swells and becomes rounded. - Synaptic stripping: synaptic terminals are seen to withdraw from the surface of the injured neuronal cell body and its dendrites NORMAL: - centrally located nucleus w/ prominent nucleolus. Spread out nissel’s substances

Answer 113

collection of RER (Rough endoplasmic reticulum) with ribosomes.

Answer 114

retrograde degeneration | (cause going from distal to proximal).

Answer 115

Wallerian Degeneration.

Answer 116

1) Anti-inflammation 2) Growth factors 3) Stimulate Schwann cell to differentiate and remeylinate

Answer 117

- MQ secret vascular endothelium growth factor that promotes angiogenesis - it will make a connection between the distal and the proximal (bridge) - Along this blood vessel the growing/ proliferating Schwann cell & THEN the axons will be guided till it reaches the distal segment

Answer 118

axons are attracted by chemotropic factors secreted by Schwann cells in the distal stump. Growth-stimulating factors exist within the distal stump

Answer 119

Inhibitory factors are present in the perineurium to inhibit the axons from leaving the nerve.

Answer 120

1. Ability of Schwann cells to proliferate. 2. Presence of Basal Lamina/Endoneurium. 3. MQ

Answer 121

- Loss of sensibility and voluntary movement below the lesion - bilateral LMN paralysis and muscular atrophy IN the segment of the lesion - bilateral SPASTIC paralysis (UMN) BELOW the lvl of the lesion - bilateral babinski sign

Answer 122

- due to anterior spinal artery occlusion - bilateral LMN paralysis and muscular atrophy IN the segment of the lesion - bilateral SPASTIC paralysis (UMN) BELOW the lvl of the lesion - the bilateral spasticity is caused by interruption of anterior corticospinal tract - the bilateral paralysis is caused by interruption of tracts other than corticospinal tract - posterior column is preserved (gracilis and cuneatus)

Answer 123

- bilateral LMN paralysis on the same segment bcs of damage to the anterior grey horn - bilateral spastic paralysis (UMN) below the lesion - bilateral loss of pain, temp and light touch bcs the crossing fibers of spinothalamic are affected

Answer 124

- aka hemisection - epsilateral babinski sign - epsilateral LMN paralysis/ hypotonia/ ansthesia - epsilateral loss of posterior colmn, so loss of proprioception - epsilateral spastic paralysis (UMN) below the lesion - contralateral loss of pain, temp and crude touch (tactile sense) two to three segments BELOW the lesion

Answer 125

- when there is an abnormal dilation of the spinal cord lesion - spinothalamic tract will be affected due to its crossing in the anterior white commissure (NO PAIN) - bilateral loss of sensation but ONLY at the site of the lesion and usually in upper limbs - eg. patient comes with repeated burns in fingers w/out being aware - when it develops to anterior grey horn -> wasting of upper limbs muscles (LMN) - if they extend even more and disturb lateral corticospinal region they will cause UMN problems below the lvl of lesion - - eg. patient comes with repeated burns in fingers of both hands w/out being aware, after a while she develops weakness in upper limbs and her gait becomes spastic and disturbed - if the extension of lesion is lateral at T1 symptoms apply to eyes, it will lead to bilateral horner syndrome -Why not the whole body? bcz the damage below the crossing.

Answer 126

- caused by polio - anterior grey column is affected - immobilization of lower limbs

Answer 127

- ALS - both LMN (corticospinal tract) - and UMN (anterior grey horn)

Answer 128

- will produce UMN manifestations = Spastic paralysis (in both cases) - either in the cortex/ brainstem (motor decussation happens here in pyramids) or in spine 1. in spine: EPSILATERAL UMN lesion - eg. Lesion of the lateral corticospinal Tract (in the spinal cord) 2. in cortex/ brainstem: - before decussation so it's CONTRALATERAL UMN lesion - Example: vascular lesion of the Cerebral cortex - Weber's syndrome: occlusion of a branch of post. Cerebral artery that Supplies the midbrain 3. damage to the anterior corticospinal tract No obvious weakness cause it's anterior

Answer 129

- occlusion of a branch of post. Cerebral artery that Supplies the midbrain - CONTRALATERAL UMN lesion

Answer 130

presence of inhibitory interneurones | - pain (It can open the gate to more pain & amplify it or shut the gate so the pain becomes less

Answer 131

respond to high- | threshold, noxious stimuli (C- and A delta-fibres), encoding location and intensity of the pain

Answer 132

mildnoxious stimulus leads to an amplified pain response (something that already causes pain but it's amplified)

Answer 133

pain due to a NON-painful stimulus | eg. brush or clothes on their body causes pain

Answer 134

expectation of pain when told verbally or non verbally. | e.g. if you’re going to do a surgery again. Before they even touch, you’d be in pain.

Answer 135

do NOT transmit noxious stimuli, they just carry touch sensation and they end in deep dorsal horn.

Answer 136

transmit noxious stimuli of mechanical & thermoceptive quality (polymodal) ends in both superficially & deep.

Answer 137

transmit Nociceptive mechanical, thermoceptive and chemical stimuli (polymodal) end in superficial dorsal horn. - eg. acidity, spicy food

Answer 138

1. Primary hyperalgesia: - it's where you can see the damage - is due to sensitisation of nociceptors in the periphery (peripheral sensitisation) 2. Secondary hyperalgesia: - Area around it that is also painful - is due to sensitisation of spinal cord dorsal horn neurons (central sensitisation)

Answer 139

Inflammation. - > Inflammatory mediators (eg. histamine) acting on their receptors (H1 receptor) - > sensitisation of nociceptors - > peripheral sensitisation

Answer 140

- Histamine from mast cells -> H1 receptor - Bradykinin from macrophages, mast cells and damaged tissue -> B2/B1 receptors - PGE2 from mast cells -> EP receptors - ATP from platelets and damaged tissue -> P2X3 receptor - H+ from inflammation -> ASIC receptor

Answer 141

- glutamate - > act on AMPA and NMDA receptors - substance P -> act on NK-1 receptor - 5 HT (seretonin) -> act on 5HT3 receptor (BUT if it acts on 5HT1 it is INHIBITORY)

Answer 142

- GABA -> act on GABA-A and GABA-B - opioid peptides -> act on opioid receptors - Noradrenaline -> act on alpha 2 adrenoceptors (a2-AR) - 5 HT (seretonin) -> act on 5HT1 receptor - cannabinoids -> act on cannabinoid receptors

Answer 143

- for acute pain - fast excitatory synaptic transmission -> sets baselinenociceptive transmission (acute pain) - Ion channel, once activated, is more selective to Na+ entry than Ca2+ (more Na) - Antagonist =CNQX (cyanquixaline) - AMPA receptors CANNOT be blocked (but NMDA receptors can)

Answer 144

- for chronic pain - more complicated to activate - ion channel w/ Mg sitting in the middle blocking the channel stoping it from being activated. - Once Mg is removed, Na & Ca can go in & K+ can go out.

Answer 145

- the cell that the NMDA receptor is on has to be consistently depolarized - so there’s an electrical activity that helps this Mg leave its place for Na & Ca to go in.

Answer 146

- Neuropeptide from the neurokinin (tachykinin) family - Neurotransmitter in the CNS, released after HIGH intensity noxiousstimulation - Co-released from primary afferent fibres with other peptides - Acts on neurokinin 1 (NK-1) receptor

Answer 147

- G-protein coupled (NOT an ion channel) - postsynaptic - Increases release of Ca2+ from intracellular stores via generation of inositol trisphosphate (IP3) (Ca2+ increase in the cell) - Involved in mood, stress, anxiety and pain Both NK-1 and NMDA receptors are involved in central sensitisation

Answer 148

- Remember: central sensitisation causes pain around the damaged area - pain sensation coming -> substance P act on NK1 and Glu acts on AMPA -> Na and Ca go into the cell -> Primary alpha fibers (prostanoids and NO in spinal cored) start sending another msg that retrogradely diffuse back to c fibers and facilitate more transmitter release (the previous step happened WITHOUT a stimulus, it's a cycle of pain/ LOOP of central sensitisation stimulation) -> more glu and peptides (substance P) ->more Ca released -> depolarized cell -> Few times of this and Mg block is removed (NMDA activated) - NMDA and substance P are involved in central sensitisation

Answer 149

- major inhibitory transmitter in CNS - acts on GABA-A predominantly forms a tonic control of excitatory transmission * GABA A receptor: ion channel * GABA B receptor: G protein coupled - Once GABA & BZDs bind—> the channel opens, Cl- goes in - fast postsynaptic inhibition bcz Chloride influx hyperpolarises the cell causes inhibition - inhibitory Target of BZDs, barbiturates

Answer 150

PAG (periaqueductal grey area) eg. urgeries done on monkeys w an electrode going into the PAG area -> animal isn’t feeling pain so: electrical stimulation of PAG—> analgesia - morphine microinjection in PAG -> analgesia - if you activate the NMDA receptor (involved in pain) —> also got analgesia. - Reversed when given antagonist to morphine & antagonist to NMDA receptor.

Answer 151

- Reciprocal connections back toPAGand other supraspinal sites - Caudal projections back to spinal cord - RVM stimulation both inhibits and facilitates (centralsensitisation) spinal cord nociception (pain) - in inflammatory diseases it inhibits pain - in neuropathic pain it increases pain

Answer 152

1. Noradrenaline | 2. Serotonin (5-HT)

Answer 153

acting on a2-adrenoceptors has inhibitory effects

Answer 154

- has both inhibitory and excitatory - 5HT1 is inhibitory - 5HT3 is excitatory - 5HT3 is involved in vomiting. - Ondansetron is an antagonist to 5-HT3 - After this channel is activated, it’s permeable to monovalent cations as well as Ca+

Answer 155

- exists in a (top-down) descending pain modulatory circuit, underlies placebo analgesia and involves areas of the pain matrix as well as endogenous opioid mediated inhibition Important: - Nalaxone blocks the opioid receptors. - (IMPORTANT) Studies included placebo analgesia CANNOT be experienced if naloxone blocks the oipid receptors (endogenous opioid peptides cannot access the receptors) - if i'm doing a study for placebo and gave the patient nalaxone to block their opiod receptors -> the study is not going to work cause the top down thing doesn't work anymore - so, top down enogenous pain control involves endogenous opioid peptides.

Week 1 Flashcards

(183 cards)