Skeleton and muscles

Question 1

Which are the three types of cytoskeleton?

Answer 1

Microtubule, actin filaments and intermediate filaments

Question 2

What are motor proteins and which three types are there?

Answer 2

Enzymes that use energy from ATP to move.
1. Dyneins: walk on microtubule in cilia and flagella
2. Kinesis: walk on microtubule
3. Myosins: walk on actin filaments

Question 3

What are the characteristics of skeletal muscles?

Answer 3

Voluntary movements, multinucleated and rich in mitochondria.

Question 4

What is a muscle fiber and which types are there?

Answer 4

Multinucleated muscle cell.
1. Slow-switched. Uses fat and has a steady power.
2. Fast-switched. Glycolytic and has explosive power.

Question 5

What are flexor muscles and extensor muscles?

Answer 5

Flexor muscles: muscles that decrease the angle between bones.
Extensor muscles: muscles that increase the angle between bones.

Question 6

What are the characteristics of cardiac muscles?

Answer 6

One central nuclei per cell, numerous mitochondria, striated and rich in gap junctions.

Question 7

What are the characteristics of smooth muscles?

Answer 7

Not striated, non-directional contraction, gap junctions and filaments scattered throughout the cell.

Question 8

What do tendons and ligaments do?

Answer 8

Tendons: attach muscle to bone
Ligament: attach bone to bone

Question 9

What are the different parts in neural basis that controls movements?

Answer 9

Cortex: motor planning and visual feedback
Basal ganglia: controls voluntary movements
Brain stem: vary the speed and quality of movements
Spinal chord: the final common pathway for motor output

Question 10

What is a motor unit?

Answer 10

Consists of one motot neuron and all the muscle fibers it stimulates. The muscle fibers are dispersed within the muscle.

Question 11

What are the steps in the spinal reflex?

Answer 11

1. Receptor at the end of a sensory neuron
2. Nerve impulses to integration center
3. A motor neuron transfer the signal to an effector
4. An effector responds

Question 12

What are the steps in the cross-bridged cycle?

Answer 12

1. ATP bind to myosin
2. Release of actin-myosin link
3. ATP -> ADP causes myosin to change
4. ADP leaves, myosin returns to its “resting” position and bends it head
5. Power stroke that pulls the actin filaments

Question 13

What happens in the full cycle of action potential and movement of myosin at actin filaments?

Answer 13

1. ACh (released at synaptic terminal) diffuses across the synaptic cleft and binds to a receptor on an muscle fiber.
2. Action potential fires along the membrane and down T-tubules.
3. Action potential trigger Ca2+ release.
4. Ca2+ binds to troponin -> myonsin binding sites are exposed.
5. Myonsin binding sites are restored, contraction ends and muscle fiber relaxes.