Musculoskeletal system

Question 1

Define the following words from the musculoskeletal system

Latent period
Twitch
Tetany
Muscle tone (tonus)

Answer 1

Latent period: Lag between stimulation of a muscle and its response

Twitch: Single, very short contraction

Tetany: Sustained contraction, that lacks even partial relaxation

Muscle tone (tonus): A degree of sustained contraction that is always occuring

Question 2

What is the pacemaker of the heart?

Answer 2

The sinoatrial node (SA node), contains specialized cells in the right atrium, which initiate the contractions of the heart

Question 3

What are two forms of smooth muscle?

Answer 3

• Separate fibrillary fibres (eg. iris, blood vessels)

- Sheets (visceral muscle - eg bladder, uterus, peristalsis)

Question 4

Describe modulation of visceral muscle activity?

Answer 4

Visceral muscle contraction is involuntary and rhythmic. Hormones, local metabolites and the autonomic nervous system control it.

The parasympathetic nervous system activates it, and the sympathetic nervous system inhibits activity.

Question 5

What is a synctium?

Answer 5

A mass of cells which merge and can function together.

Skeletal muscles can merge into synctiums

Question 6

What is the movable and immovable end of a muscle?

Answer 6

Movable: The insertion

Immovable: The origin

When a muscle contracts, its insertion moves towards the origin

Question 7

What is abduction and adduction?

Answer 7

Abduction: Movement away from the midline of the body

Adduction: Movement towards the midline of the body

Question 8

What is a motor unit?

Answer 8

One motor neuron and its many muscle fibres

Question 9

What are four functions of bones?

Answer 9

1. Acting like levers to aid body movement
2. Storing inorganic salts (ie. Ca, phosphorous, Na and Mg
3. Production of blood cells in red marrow
4. Storing fat cells in yellow tissue

Question 10

What are the four classes of bones?

Answer 10

• Long bones
• Short bones
• Flat bones
• Irregular bones

Question 11

What is the epiphysis?

Answer 11

The expanded end of a long bone

Contains spongy bone and is surrounded by the periosteum

Question 12

What is another name for the ‘shaft’ of a bone?

Answer 12

Diaphysis

Primarily composed of compact bone

Question 13

Describe the two types of bone growth

Answer 13

Membranous bone: Layers of membranous connective tissue appear

Cartilaginous (or endochondral) bone: Cartilage appears and is then replaced by bone

Question 14

What are epiphyseal growth plates?

Answer 14

Detected in children on x-ray, this plate is a disk of cartilage between the epiphysis (end of a long bone) and diaphysis (where bone is being actively deposited/ossification)

Question 15

True or false? Joints can be immovable

Answer 15

True

They can be:

• Immovable
• Partly movable
• Freely movable

Question 16

What are ligaments?

Answer 16

Attachments between bones (bone-bone)

They are formed by dense bands of fibrous connective tissue, which reinforce the joint capsule and help to maintain bones in the proper anatomical arrangement

Question 17

What are tendons?

Answer 17

Connect muscle to bone. They are formed by the densest kind of fibrous connective tissue. Tendons allow muscular forces to be exerted even when the body (or belly) of the muscle is at some distance from the action.

Question 18

What happens physiologically if vitamin D cannot be converted to active form or if the active form becomes unable to act on its target tissue?

Answer 18

The body’s ability to absorb ingested calcium from the small intestine would be reduced.

Question 19

At the neuromuscular junction, ACh receptors are located on the:

A. Plasma membrane
B. Sarcolemma
C. Muscle surface

Answer 19

B. Sarcolemma

The sarcolemma is the muscle’s plasma membrane, and this is part of the motor end plate.

Question 20

Why was the development of striated muscle in arthropods (eg. insects) paramount to their success?

Answer 20

Increased activity

Striated muscle is very efficient at turning potential energy stored in the chemical bonds of glucose into the kinetic energy of muscle contraction. The contractile proteins are packed into dense, regular arrays to maximize power and minimize muscle bulk. Because of this efficiency, vertebrates and insects can afford to have skeletons.