Lesson 5

Question 1

2 main functions of the spinal cord:

Answer 1

1. Propagates nerve impulses
2. Integrates information

Question 2

2 main sensory tracts

Answer 2

• Spinothalamic tract
• Posterior column

Question 3

Spinothalamic tract

Answer 3

• conveys nerve impulses for sensing pain, temperature, itch, tickle, and touch, pressure, vibration

Question 4

Posterior column

Answer 4

• made up of 2 tracts gracile fasciculus & cuneate fasciculus
• conveys nerve impulses for touch, light pressure, vibration and conscious proprioception

Question 5

Conscious proprioception

Answer 5

the awareness of the positions and movements of muscles, tendons and joints

Question 6

2 main motor tracts

Answer 6

• Direct pathways
• Indirect pathways

Question 7

Direct pathways

Answer 7

• lateral corticospinal tract
• anterior corticospinal tract
• corticobulbar tract
• nerve impulses originate in cerebral cortex
• cause voluntary movements of skeletal muscle

Question 8

Indirect pathways

Answer 8

• rubrospinal tract
• tectospinal tract
• vestibulospinal tract
• lateral reticulospinal tract
• medial reticulospinal tract

Question 9

Indirect pathways nerve impulses and functions

Answer 9

• nerve impulses originate in brain stem
• causes automatic movements
• helps coordinate body mvts with visual stimuli
• maintains skeletal muscle tone
• sustained contraction of postural muscles
• major role in equilibrium by regulating muscle tone in response to movements of head

Question 10

Stimulus

Answer 10

• a change in the internal or external environment

Question 11

Reflex

Answer 11

• a fast, involuntary, unplanned sequence of actions that occurs in response to a particular stimulus
• can be inborn or learned

Question 12

*Spinal reflex

Answer 12

• when integration happens in grey matter of SC

Question 13

Cranial reflex

Answer 13

• when integration happens in brain stem

Question 14

Somatic reflex

Answer 14

• involves contraction of skeletal muscle

Question 15

Autonomic reflexes

Answer 15

• not usually consciously perceived
• involve responses of smooth mm, cardiac mm and glands

Question 16

Reflex Arc

Answer 16

• the reflex arc or reflex circuit is the pathway for nerve impulses that produce a reflex

Question 17

Reflex arc 5 components

Answer 17

1. Sensory receptor
2. Sensory neuron
3. Integrating center
4. Motor neuron
5. Effector

Question 18

monosynaptic reflex arc

Answer 18

• most simple
• a reflex pathway with only 1 synapse in the CNS (so 2 neurons and 1 synapse)

Question 19

Polysynaptic reflex arc

Answer 19

• when the integrating center consists of at least one interneuron
• involves more than 1 synapse in the CNS (so 3 neurons and 2 synapses)

Question 20

The stretch reflex

Answer 20

• contraction of a skeletal muscle in response to stretching of that muscle
• monosynaptic reflex arc
• can be elicited by tapping on tendons attached to muscles at elbow, wrist, knee and ankle joints
• stimulates muscle spindles
• muscle spindles are sensory receptors in the mm
• they monitor the change in length of the mm
• the stretch reflex is an ipsilateral reflex
• sensory nerve impulses enter the same side that the motor nerve impulses come out

Question 21

The stretch reflex

mm tone

Answer 21

-tone of a muscle is also set through muscle spindles

Muscle tone = the small degree of contraction present when a muscle is at rest

Question 22

Stretch reflex

Reciprocal innervation

Answer 22

• when parts of a neural circuit simultaneously cause contraction of 1 muscle and relaxation of its antagonists

Question 23

Stretch reflex

mm spindles relay info where?

Answer 23

-branches of the muscle spindle sensory neuron also relays information to the brain so that you know what is happening

Question 24

The tendon reflex

Answer 24

• relaxation of a muscle when there is too much tension
• prevents tearing of a tendon
• ipsilateral
• polysynaptic
• stimulates Golgi tendon organs (GTO)

Question 25

Tendon reflex Protects mm from what?

Answer 25

* this reflex protects the tendon and muscle from damage due to excessive tension * reciprocal innervation

Question 26

The flexor (withdrawal) reflex

Answer 26

* when you step on a tack, you will flex or withdraw your leg away from the painful stimulus * it is a polysynaptic reflex arc * it is ipsilateral * this is a protective reflex because it moves the limb away from a possibly damaging stimulus

Question 27

The flexor (withdrawal) reflex Type of reflex arc?

Answer 27

-it is an intersegmental reflex arc -nerve impulses from 1 sensory neuron ascend and descend in the spinal cord, activating interneurons in several segments of the spinal cord -this way a single sensory neuron can activate several motor neurons

Question 28

The crossed extensor reflex

Answer 28

* happens with the flexor reflex * when you step on a tack and withdraw or flex your leg, the other leg needs to extend so you don’t fall over * this is a contralateral reflex arc * sensory impulses enter one side of the spinal cord and motor impulses exit on the opposite side * intersegmental reflex arc * reciprocal innervation