Movement (Chapter 3)

Question 1

muscles that bedn a joint to bring the bones closer together are called…

Answer 1

flexors

Question 2

muscles that straighten the joint, increasing the angle between the bones are…

Answer 2

extensors

Question 3

flexors and extensors work in opposition.l what does this mean

Answer 3

when one of them contracts, the other relaxes

Question 4

agonists

Answer 4

muscles that promote the movements required for motions such as the bending
of an elbow

Question 5

anatgonists

Answer 5

muscles that oppose or inhibit the movement

Question 6

are agonists or anatgonists required for skilled rapid movements (like throwing a dart)

Answer 6

• movements are started by agonsists and stopped by antagonists
• allows limb to accelerate and halt with speed+precision

Question 7

co-contracion

Answer 7

for some movements, both muscles (anta, an) contract at the same time, which stabilizes or controls a movement such as holding an object at arm’s length

Question 8

what are skeletal muscles made up of

Answer 8

thousands of individual muscle cells called musle fibers.

Question 9

muscle fibres

Answer 9

each is controlled by a single alpha motor neruon that origniates in the spinal cord or brain
- each aloha motor neuron controls multiple muscles fibers (few-100)

Question 10

motor unit

Answer 10

• alpha motor neruon plus all the muscle fibers it controls

- it is the critical link between the central nervous system and skeletal muscles

Question 11

amyotrophic lateral scelerosis (ALS)

Answer 11

when motor neurons die.

- people lose the ability to move

Question 12

two divisions of the nervous system

Answer 12

central, and peripheral

Question 13

peripheral

Answer 13

nerves, and small concentrations of gray matter called ganglia. The brain sends messages to the peripheral nerves which control the muscles and internal organs

Question 14

central nerovus syte,

Answer 14

brain and spinal cord

Question 15

reflex movements

Answer 15

ocur without involvement of the brain or conscious attention. They instead depend on circuits of neurons located in or near the spinal cord itself

Question 16

knee jerk

Answer 16

• stretch/myotatic reflex
• tao of thge tendon below kneww produces a slight stretch of the knee extensor muscle
  -this stretch is sensed by receptors within the muscle (spindles)
  -

Question 17

what happens when spindles sense the extent and speed of the stretch

Answer 17

they sense the extent and speed of the stretch

• stimulate sensroy sensory neruons that send a barrage of impulses into the spinal cord
• in the spinal cord, the singles activate the alpha motor neruons that cause the stretched extensor muscle to contract which triggers the reflex
• antagonist flexor muscle has to relax at same time for the leg to kick forward

Question 18

flexion crossed extension reflex

Answer 18

extensors of the opposite leg are activated (ex. when sharp object and bare foot)

Question 19

what kind of info do muscle spindles provide?

Answer 19

• supply info about the changes in muscle length or stretch
• as a result, the brain will adjust the sensitivity of the system by a separate set of motor neruons
• these motor neruons keep the muscle spindles taut
• they re called gamma motor neurons

Question 20

where do neurons communicate with muscles

Answer 20

neuro-muscular junctions

Question 21

motor neruons

Answer 21

• carry instructions from the brain along long axons

- these long axons stretch from spinal cord to he muscles in hands and feet

Question 22

Golgi tendon organs

Answer 22

• located where the muscle fibers connect to the tendon
• they detect how much force or retnsion is applied to a muscle during ongoing movement
• this increse’s the movement’s precision

Question 23

central pattern generators (neruonal circuits)

Answer 23

• when they are activated, they produce the rhythmic patterns that occur in many movements.
  evolved in primitive vertebrates.
• the rhtyhmic patterns of muscle activation are generated by neurons within the spinal cord and brainstem circuits. They produce locomotion

Question 24

what do all complex movments require

Answer 24

• input from the brain
• the higher brain regions involved in things like conscious planning initiate:
• voluntary motion
• coordinate complex sequences of movement
• tailor behavioural output to a given situation
  THIS REQUIRES THAT THE BRAIN RELAYS COMMANDS TO THE APPROPRIATE SPINAL CIRCUITS

Question 25

motor cortex

Answer 25

• essential for voluntary movement
• send signals that directly control the activation of alpha motor neurons in the spine
• some of the neurons in the cortex control the movement of functionally related muscles in an individual body part such as hand or arm. They are important for finely-tuned motor skills
• other neurons will direct the coordinated movement of a limb to a particular point in space (ex. hand delivering food to mouth)

Question 26

several other brain regions particpate in parallel circuits or “loops” to modulate motor control. What regions do these include?

Answer 26

• the basal ganglia, thalamus, cerebellum, large number of neuron groups in midbrain and brainstem

Question 27

two paths that the basal ganglia ecnompasses:

Answer 27

• one path appears to facilitate the desired motor program

- another path will suppress unwanted, competing actions

Question 28

parkinson’s disease

Answer 28

• dysfunction of the basal ganglia.

- they experience degeneration of neurons in a brain region called the substantial nigra

Question 29

substantia ngira

Answer 29

• the neurons relay signals to the basal ganglia using the neurotransmitter dopamine

Question 30

dopamine

Answer 30

key chemical inovled in motor control

Question 31

what happens when there is a depletion of dopamine ni the brain

Answer 31

• it gives rise to the hallmark symptoms of Parkinson’s

Question 32

sympotoms of Parkinson’s

Answer 32

• tremor, rigidiity,

- sometimes akineseia (inability to move)

Question 33

Huntington’s disease

Answer 33

• often display uncontrolled jerking or twicthich movements (part. in the face or extremities)

Question 34

from wehre do the Huntington’s symptoms stem

Answer 34

• selective loss of ihnbitory neurons in the basal ganglia

- this eliminates the suppressionof random involuntary movements

Question 35

cerebellum

Answer 35

crucial for coordinating and fine-tuning skilled movement

• receives direct input from sensory receptors in the limbs and head as well as most areas of the cerebral cortex
• neruons in cerebellum integrate this sensory info to ensure proper timing and integration of muscle action
• enables us to produce fluid movment

Question 36

other important roles of cerebellu

Answer 36

• essential to a wide range of motor learning and coordination
• allows u to adapt to the unexpected
• allows u to perform motor tasks with increasing accuracy and skill (through regined and shapened memory programs)
• helps us recalibrate our movements as our own bodies change,

Question 37

what happens when the function of the cerebellum is disturbed

Answer 37

poor coordination, disor-ders of balance, and even difficulties in speech, one of the most intricate forms of movement control.

Question 38

common cause of acquired cerebellar degeneration

Answer 38

• long-term alchohol abuse

- sympotoms incld

Question 39

symptoms of cerebellar degeneration

Answer 39

• l symptoms are poor coordina-tion, an unsteady walk or stumbling gait, changes in speech, and difficulty with fine motor skills including eating, writing, and dressing.