Muscle VI

Question 1

What is cachexia

Answer 1

Weakness and/or wasting due to chronic disease
Ex) cancer, ALS, muscular dystrophy

Question 2

What are skeletal muscle reflexes

Answer 2

Changes in amount of force generated in skeletal muscle at level of spinal cord due to sensory input
Ex) adjust to stabilize movement, prevent damage

Question 3

What are two ways receptors sense changes in joint movements, muscle tension, and muscle length and cause muscle reflex

Answer 3

• if muscle contraction needed CNS activates motor neurons to muscle fibers
• if relaxation needed sensory input activates inhibitory interneurons in CNS which inhibits motor neuron activity

Question 4

What are the four components of skeletal muscle reflexes

Answer 4

1. Sensory receptor (senses sitmulus)
2. Integrating center (spinal cord)
3. Efferent neurons
4. Effectors (target tissue)

Question 5

What is a monosynaptic reflex

Answer 5

Single synapse between afferent and efferent neurons (basic reflex)

Question 6

What is a polysynaptic reflexes

Answer 6

Two or more synapses
- synaptic motor reflex have both synapses in CNS
- most reflexes

Question 7

What are proprioceptors

Answer 7

Provide info into CNS about position of our limbs in space, movements, and effort exerted by skeletal muscles

Question 8

What are 3 types of proprioceptors

Answer 8

1. Muscle spindle
2. Golgi tendon organ
3. Joint receptors

Question 9

What are joint receptors

Answer 9

Found in capsules and ligaments around joints and are stimulated by mechanical distortion that accompany changes in position of bones

Question 10

What are muscle spindles

Answer 10

• Small elongated stretch receptors scattered among and arranged parallel to skeletal muscle fibers
• send info to CNS about muscle length + change in muscle length

Question 11

What are muscle spindles made of

Answer 11

Sensory neuron wrapped around intrafusal muscle fibers innervated by gamma motor neurons
- extramural muscle fibers (regular) around and innervated by alpha motor neurons
- Toni ally active (always firing APs)

Question 12

What is a muscle spindle reflex

Answer 12

Addition of load stretches the muscle and the spindles, creating reflex contraction (respond to change in length and increase force of contraction)

Question 13

Wha this alpha-gamma Coactivation

Answer 13

Maintains spindle function even when alpha motor neurons fires and gamma motor neuron fires and muscle and intrafusal fibers both contract

Question 14

What is a golgi tendon organ

Answer 14

Sensory neuron interwoven among collagen fibers inside a connective tissue capsule
- collagen fibers pull tights, pinch sensory neuron
- not tonic

Question 15

What do Golgi tendon organs do

Answer 15

Respond to muscle tension (at junction of muscle and tendon)
- proposed to primarily control inhibitory reflexes to prevent muscle damage
- plays bigger role in controlling force within muscles and stability around joints

Question 16

What is the Golgi tendon reflex

Answer 16

Protects muscle from excessively heavy loads by causing muscle to relax and drop load

Question 17

What do stretch reflexes and reciprocal inhibition control

Answer 17

• movement around joint
• stimulus of sensory receptors promote contraction of one muscle but relaxation or inhibition of antagonist

Question 18

What are flexion reflexes

Answer 18

Pull limbs away from painful stimuli
- ex) nociceptors sense pain and allow movement very rapidly

Question 19

What is the crossed extensor reflex

Answer 19

Flexion reflex in one limb causes extension in opposite limb
- coordination of reflexes with postural adjustments is essential in maintaining balance

Question 20

What happens in a crossed extensor reflex when painful stimulus is step on tack

Answer 20

• flexors contract, moving foot away from pain
• extensors contract in other leg as weight shifts to it

Question 21

What is cardiac muscle made up of

Answer 21

• cardiac myocytes (myocardial muscle cells)
• interconnected by intercalated disks