physics 1

Question 1

Exoskeleton versus endoskeleton

Answer 1

An exoskeleton is an external skeleton that protects the outer surface of an organism. An endoskeleton is an internal skeleton that supports and protects an organism’s internal structures.

Question 2

Extensor versus flexor muscle

Answer 2

Extensor muscles increase the angle between the 2 sides of a joint. Flexor muscles decrease the angle between the 2 sides of a joint.

Question 3

Tendons versus ligaments

Answer 3

Tendons bind muscle to bone. Ligaments bind bone to bone.

Question 4

Ball and socket joints versus hinge joints

Answer 4

Ball and socket joints can move bones along several axes (ex: hip). Hinge joints can move bones along one axis (ex: elbow).

Question 5

Muscles in limbs work antagonistically… meaning?

Answer 5

When one muscle contracts, the other relaxes.

Question 6

Bicep versus tricep

Answer 6

The bicep is the muscle located above the humerus bone. The tricep is the muscle located below the humerus bone.

Question 7

Role of bones/exoskeletons

Answer 7

The role of the bones and exoskeleton are to provide anchorage for muscles and act as levers.

Question 8

Joint

Answer 8

A joint is where 2 bones come together which allows for movement.

Question 9

Role of cartilage

Answer 9

The role of cartilage is to protect and prevent friction between the ends of the bones by covering them.

Question 10

Synovial joints

Answer 10

Synovial joints contain a cavity filled with fluid which reduces friction and allows the bones to move freely. Synovial joints are an example of ball and socket joints because they can move in multiple directions.

Question 11

What are striated muscles and which muscles are striated?

Answer 11

Striated muscles are muscles that appear stripped under a microscope. Striated muscles consist of a light and dark band that are made of actin and myosin, respectively. Skeletal and cardiac muscles are striated, however smooth muscles are not.

Question 12

Muscle cells

Answer 12

Muscle cells are elongated, contain many nuclei and mitochondria, and are surrounded by sarcolemma.

Question 13

Muscle fibers

Answer 13

Muscle fibers contain the sarcoplasmic reticulum which is needed for muscle contractions because it releases calcium ions, which enables the muscles to contract or relax.

Question 14

Sarcolemma, sarcoplasm, and sarcoplasmic reticulum

Answer 14

Sarcolemma is the cell membrane of a muscle fiber. Sarcoplasm is the cytoplasm of a muscle fiber. Sarcoplasmic reticulum is a specialized type of smooth ER of a muscle fiber that pumps in and stores calcium ions.

Question 15

Motor neuron axon

Answer 15

The motor neuron axon is the end of a neuron that triggers muscle contraction.

Question 16

How to draw a sarcomere

Answer 16

The Z-lines border the sarcomere and hold the thin actin filaments. The thick myosin filaments are held by the M-line which is in the middle of the two Z-lines.

Question 17

Sliding filament theory

Answer 17

The sliding filament theory explains the contraction of skeletal muscles. The process begins with myosin being in its cocked position. The myosin head contains ATP, but it cannot bind to actin because it’s blocked by tropomyosin. Calcium that is released from the SR binds to troponin, which moves tropomyosin off of actin to reveal actin’s binding sites. The myosin head binds to actin and forms a cross-bridge. The powerstroke is then initiated, meaning that the myosin heads change position to forcibly slide the filaments past each other. When the powerstroke ends, myosin detaches from actin and myosin returns to its cocked position.