reflexes

Question 1

what are the two functions of the spinal chord

Answer 1

1. neuronal link bw the brain and the PNS
2. integrating centre for spinal reflexes

Question 2

how many pairs of spinal nerves are there

Answer 2

31

Question 3

where do spinal nerves come out from

Answer 3

from spaces between adjascent vertebrae

Question 4

how many pairs of cervical (neck) nerves are there

Answer 4

8

Question 5

how many pars of thoracic (chest) nerves are there

Answer 5

12

Question 6

how many pairs of lumbar (abdominal) nerves are there

Answer 6

5

Question 7

how many pairs of coccygeal (tailbone) nerves are there

Answer 7

1

Question 8

how many nerves of sacreal (pelvic) nerves are there

Answer 8

5

Question 9

what connects spinal nerves with each side of the spinal chord

Answer 9

dorsal root and ventral root

Question 10

what fibres are there in the spinal nerve

Answer 10

afferent and efferent fibres

Question 11

what is a nerve

Answer 11

a bundle of peripheral neuronal axons enclosed by a connective tissue covering and following the same pathway

Question 12

nerve fascicle

Answer 12

many axons bunbdled in connective tissue

Question 13

how is white matter organized

Answer 13

into nerve tracts

Question 14

what are nerve tracts

Answer 14

bundles of nerve fibres with a similar function. each begins or ends with a particular area of the brain

Question 15

ascending nerve tracts

Answer 15

afferent, sensory input

Question 16

descending nerve tracts

Answer 16

efferent, motor output

Question 17

how many and what are the horns that divide up the grey matter

Answer 17

1. dorsal horn: contains cell bodies of interneurons on which afferent neurons terminate
2. ventral horn: contains cell bodies of efferent motor neurons supplying skeletal muscles
3. lateral horn: contains cell bodies of autonomic sympathetic nerve fibres

Question 18

reflex

Answer 18

involuntary stereotyped response to a sensory input occuring automatically without conscious effort linking biological stimulus with response

Question 19

how many and what are the two types of reflexes

Answer 19

1. simple or basic (innate)- built in unlearned responses
2. acquired or conditioned reflexes (practice and learning)- result of practice and learning

Question 20

range of reflexes

Answer 20

simple to complex neural subroutines

Question 21

somatic (monosynaptic or polysynaptic)

Answer 21

somatic motor neurons and skeletal muscles
-spinal- integrated in spinal chord
-cranial- integrated in the brain

Question 22

autonomic or visceral (polysynaptic)

Answer 22

involve autonomic neurons (sympathetic or parasympathetic)
- spinal- urination/ defication
-integrated in brain- brainstem, hypothalamus, thalamus, homeostasis (gag, vomiting, sneezing, coughing, swallowing)

Question 23

how many components are in a reflex pathway

Answer 23

5

Question 24

what are the five components in a reflex pathway

Answer 24

1. sensory receptor (muscle spindles in the case of somatic muscle reflexes)
2. afferent pathway to CNS (sensory axon)
3. integrating centre consisting of one or more synapses in the CNS
4. efferent pathway to the periphery (motor axon)
5. effector (mucsle)

Question 25

monosynaptic reflex

Answer 25

has a single synapse between the afferent and efferent neurons

Question 26

what kind of reflex is a stretch reflex

Answer 26

monosynaptic reflex

Question 27

example of stretch reflex

Answer 27

pateller tendon (knee jerk reflex)

Question 28

what is the preliminary assesment of the nervous system function

Answer 28

stretch reflex

Question 29

polysynaptic reflexes

Answer 29

have two or more synapsys

Question 30

example of a polysynaptic reflex

Answer 30

flexion (withdrawal) reflex touching something hot

Question 31

muscle spindles

Answer 31

in muscles and sense stretch

Question 32

golgi tendon organ

Answer 32

in tendon and sense force

Question 33

joint receptors

Answer 33

sense pressure. position

Question 34

proprioceptros

Answer 34

skeletal muscle reflex sensory receptors

Question 35

isotonic contraction

Answer 35

alpha motor neurons are stimulated to generate contraction.

Question 36

muscle contraction and receptor response

Answer 36

alpha motor neurons are stimulated to generate contraction. the length changes by tension is constant. when the whole muscle mass shortens, the spindle also passively shortens. the firing rates of the spindle afferent axons are reduces because the tension in the receptor portion of the intrafusal fibres is relieved. without adjustment, they will no longer detect changes in muscle length

Question 37

function of v neurons

Answer 37

modulate sensitivty of the spindles

Question 38

unloading spindles

Answer 38

the intrafusal fibres slacken when a muscle shortens

Question 39

how is it ensured that info on cahnges in muscle length are transmitted

Answer 39

the CNS regulates the loading of the intrafusal fibres with v motor neurons

Question 40

what is this called "the CNS regulates the loading of the intrafusal fibres with v motor neurons"

Answer 40

innervation via reticulospinal and vestibulospinal tracts

Question 41

isometric contraction

Answer 41

a motor neurons are stimulated with the muscle firmly fixed at both ends. tension inc but length is constant therefore due to no change in length, the fiting of spindle afferents stays the same. tension is transferred to GTO and those afferents (IB) inc firing

Question 42

golgi tendon organs

Answer 42

sense tension

Question 43

loss or reduction of reflex

Answer 43

interruption of refllex arc by either peripheral sensory or lower motor neuron lesions (LMN). reduces or eliminates muscle stretch reflex and reduces muscle tone. loss of innervation to the muscle

Question 44

increased reflex and muscle tone (spasticity)

Answer 44

injury to upper motor neurons - UMN- above the anterior horn cell (spinal chord, motor cortex,) leads to loss of descending inhibition. increases muscle tone - hyperreflexia

Question 45

UMN

Answer 45

neurons in higher brain levels that influence neurons in spinal chord

Question 46

LMN

Answer 46

effector neurons in spinal chord

Question 47

muscle stretch reflex