Muscle Tissue Lecture 4

Question 1

Slow Oxidative Muscle Fibers

Answer 1

• 3x longer contraction time than fast fibers
• Half diameter of fast fibers
• Sustained contractions, fatigue resistant
• Primarily aerobic ATP production
• Extensive capillary network
• Contains myoglobin pigment (O2 binding)
• Abundant mitochondria
• Appears dark red

Question 2

Fast Glycolytic Muscle Fibers

Answer 2

• Reach peak tension in <0.01 sec
• Large diameter; densely packed myofibrils
• Large glycogen reserves, few mitochondria
• Powerful contractions
• Rapid fatigue due to anaerobic ATP production
• Appears white due to lack of myoglobin

Question 3

Fast Oxidative Muscle Fibers

Answer 3

• Fast Oxidative
• Intermediate size
• Light red color, rich in mitochondria & blood capillaries
• Utilizes both aerobic metabolism and anaerobic glycolysis
• Faster contractions than Slow Oxidative

Question 4

Red Muscle

Answer 4

• High blood flow, myoglobin, mitochondria
• High fatigue resistance, good endurance
• Small diameter fibers (e.g., postural muscles)

Question 5

White Muscle

Answer 5

• Low blood flow, myoglobin, mitochondria
• Low fatigue resistance
• Large diameter fibers (e.g., eye muscles)

Question 6

Proprioception

Answer 6

• Sense of body position and movement
• Maintains equilibrium and balance
• Mediated by proprioceptors in muscles

Question 7

Muscle Spindles

Answer 7

• Adjust to changes in muscle length (stretch)
• Made up of intrafusal muscle fibers
• Specialized sensory organs within muscle
• Sensory and motor nerve endings present

Question 8

Muscle Spindle Nerve Endings

Answer 8

• Sensory nerve endings deliver information to the nervous system
• Motor nerve endings regulate spindle sensitivity

Question 9

Gamma Motor Neurons

Answer 9

• Adjust spindle tension
• Increased stimulation enhances spindle sensitivity

Question 10

Stretch Reflex

Answer 10

Protective reflex triggered by rapid muscle stretching

Question 11

Golgi Tendon Organs (GTOs)

Answer 11

• Located at musculotendinous junction
• Monitor muscle tension during contraction
• Participate in Golgi tendon reflex, inhibiting muscle contraction to protect tissue

Question 12

Muscular Dystrophy

Answer 12

• Inherited muscle degeneration diseases
• Main type: Duchenne muscular dystrophy (DMD)
• Sex-linked recessive inheritance (affects males)
• Lack of dystrophin protein causes sarcolemma tears
• Symptoms appear in childhood, leading to death by 20
• No cure; ongoing stem cell and genetic research

Question 13

Myasthenia Gravis (MG)

Answer 13

• Autoimmune disorder affecting ACh receptors
• Results in progressive muscle weakness and fatigue
• Initial weakness in face, neck, and jaw muscles
• May lead to respiratory or cardiac paralysis

Question 14

Fibromyalgia (FM)

Answer 14

• Idiopathic musculoskeletal disorder causing widespread pain and tenderness
• More common in women
• Symptoms include pain at rest, during exertion, and upon pressure
• Associated with headaches, insomnia, fatigue, and depression
• Treatments include antidepressants, NSAIDs, massage, physiotherapy, chiropractic care, heat therapy, and exercise
• Abnormal pain perception processing leads to heightened sensitivity to pain