Chapter 11.2

Question 1

What are the body systems responsible for the control of movement?

Answer 1

-Skeletal system: consists of bones that act as levers and provide a structure for the muscles to pull
-Muscular system: muscles deliver the force required to move one bone in relation to another
-Nervous system: delivers signals to the muscles which cause them to contract and create movement

Question 2

What are skeletons?

Answer 2

A rigid framework that function to provide support and protection for body organs

Question 3

What are the different types of skeletons?

Answer 3

Endoskeleton which consists of numerous bones and Exoskeleton which is made of connected segments

Question 4

How do skeletons facilitate movement in organisms?

Answer 4

Provide a surface for muscle attachment

Question 5

What are ligaments?

Answer 5

Bones connected to other bones

Question 6

What are tendons?

Answer 6

Bones connected to muscles

Question 7

What are synovial joints?

Answer 7

Are capsules that surround the articulating surfaces of two bones

Question 8

What is the function of joints?

Answer 8

To maintain structural stability by allowing certain movements but not others

Question 9

What are the three main features of a synovial joint?

Answer 9

Joint capsule – Seals the joint space and provides stability by restricting the range of possible movements
Cartilage – Lines the bone surface to facilitate smoother movement, as well as absorbing shock and distributing load
Synovial fluid – Provides oxygen and nutrition to the cartilage, as well as lubrication (reduces friction)

Question 10

What are the six types of synovial joints?

Answer 10

Plane joints (least mobility), hinge joints, pivot joints, condyloid joints, saddle joints, ball and socket joints (most mobility)

Question 11

What type of joint is the human elbow?

Answer 11

Hinge joint

Question 12

Where is the elbow joint found?

Answer 12

Between the humerus and ulna/radius

Question 13

What bones does the muscle connect?

Answer 13

A static bone to a moving bone

Question 14

How do skeletal muscles exist?

Answer 14

In antagonistic pairs

Question 15

What are examples of opposing movements?

Answer 15

Flexion vs extension, abduction vs adduction, protraction vs retraction

Question 16

What allows insects to jump?

Answer 16

Hind legs

Question 17

What are the different parts of the exoskeleton of the hind leg?

Answer 17

Femur (upper leg), tibia (middle leg) and tarsus (lower leg)

Question 18

How are the femur and tibia connected?

Answer 18

By 2 antagonistic muscles: flexor tibiae muscle and extensor tibiae muscle

Question 19

How does the insect prepare for pushing off the ground when jumping?

Answer 19

When the flexor muscle contracts, the extensor muscle relaxes and the tibia and femur are brought closer together

Question 20

How does the insect eventually jump?

Answer 20

When the extensor muscle contracts, the flexor muscle relaxes and the tibia is pushed away from the femur

Question 21

What are skeletal muscles consisted off?

Answer 21

Tightly packaged muscular bundles surrounded by connective tissue

Question 22

What are muscular bundles consisted off?

Answer 22

Muscle fibers which are formed from the fusion of muscle cells

Question 23

What are the muscle fibers made of?

Answer 23

Myofibrils which run the length of the fiber and is responsible for muscle contraction

Question 24

How can the myofibrils be divided?

Answer 24

Into sarcomeres which represent one contractile unit

Question 25

What are the features of muscle fibers which facilitate muscle contraction?

Answer 25

-They are multinucleate
-They have a large number of mitochondria
-Sarcoplasmic reticulum that stores calcium ions
-Tubular myofibrils made up of two different myofilaments – thin filament (actin) and thick filament (myosin)
-Sarcolemma that contains invaginations called T tubules

Question 26

How are the myofilaments held in a sarcomere?

Answer 26

By dense protein discs called Z lines

Question 27

How are the myosin filaments held in place?

Answer 27

Due to the actin filaments that radiate from the Z lines

Question 28

What is the A band?

Answer 28

Centre of the sarcomere that appears darker due to the overlap of both actin and myosin filaments

Question 29

What is the I band?

Answer 29

Peripheries of the sarcomere that appear lighter as only actin is present in this region

Question 30

What is the H zone?

Answer 30

Area where only myosin is present

Question 31

What is the first step of muscle contraction and how does it happen?

Answer 31

Depolarization and Calcium Ion Release. An action potential from a motor neuron triggers the release of acetylcholine into the motor end plate
Acetylcholine initiates depolarization within the sarcolemma, which is spread through the muscle fiber via T tubules Depolarization causes the sarcoplasmic reticulum to release stores of calcium ions (Ca2+)

Question 32

What is the second step of muscle contraction and how does it happen?

Answer 32

Actin and Myosin Cross-Bridge Formation. On actin, the binding sites for the myosin heads are covered by a blocking complex (troponin and tropomyosin). Calcium ions bind to troponin and reconfigure the complex, exposing the binding sites for the myosin heads. The myosin heads then form a cross-bridge with the actin filaments

Question 33

What is the third step of muscle contraction and how does it happen?

Answer 33

Sliding Mechanism of Actin and Myosin. ATP binds to the myosin head, breaking the cross-bridge between actin and myosin. ATP hydrolysis causes the myosin heads to change position and swivel, moving them towards the next actin binding site
The myosin heads bind to the new actin sites and return to their original conformation. This reorientation drags the actin along the myosin in a sliding mechanism

Question 34

What is the last step of muscle contraction?

Answer 34

Sarcomere Shortening. As actin filaments are anchored to Z lines, the dragging of actin pulls the Z lines closer together, shortening the sarcomere. As the individual sarcomeres become shorter in length, the muscle fibers as a whole contracts