Chapter 11 - The Musculoskeletal System

Question 1

What are the three types of muscles?

Answer 1

Skeletal
Involuntary
Cardiac

Question 2

What are the three properties that allow muscles to work together to create movement?

Answer 2

Contraction
Extensibility
Elasticity

Question 3

Briefly explain the structure of skeletal muscles

Answer 3

• muscle cells are held together in bundles. They are also called muscle fibres.
• muscle fibres are surrounded by a sheath of connective tissue that allows it to easily slide over/under other muscles. It is the connective tissue that gives meat its toughness.

Question 4

What happens to the connective tissue that surrounds muscle fibres as a person gets older?

Answer 4

• As a person gets older, the amount of connective tissue increases and the strength that person has decreases

Question 5

What is the thin, transparent plasma membrane that surrounds a muscle fibre?

Answer 5

The sacrolemma. The sacrolemma contains sacroplasm.

Question 6

What are microfibrils?

Answer 6

Each microfibril is made up of microfilaments that are made up of the proteins actin and myosin. The microfilaments are the actual units involved in the contraction of muscle.
This arrangement gives skeletal and cardiac muscle their striated appearance.

Question 7

What are the two types of myofilaments?

Answer 7

THICK myofilaments composed of myosin

THIN myofilaments composed of actin

Question 8

Give a summary of the muscle structure (muscle fibres?

Answer 8

A sheath of connective tissue holds muscle fibres together. Muscle fibres are surrounded by sarcolemma and contain cytoplasm called sarcoplasm. Inside this sarcoplasm are myofibrils that are made of of myofilaments that are made up of two types of proteins ; actin as myosin.

Question 9

Label a sacromere and the process of muscle contraction. (Sliding filament model)

Answer 9

Sacromeres 
Z line
I band 
A band 
Actin 
Myosin

Question 10

What are the difference between tendons and ligaments?

Answer 10

Tendons attach bones to muscle or muscle to muscle

Ligaments attach bones to bones

Question 11

Why are skeletal muscles always grouped in pairs?

Answer 11

Muscles can only contract to move the skeleton one way. It needs a partner to move the skeleton the opposite way. These pairs of muscles are called antagonists.

The agonist moves forward for example and the antagonist does the opposite

Question 12

What are synergists?

Answer 12

Synergists are muscles that help the prime mover. They may ;
- produce the same movement as a prime mover
- steady a joint during a particular movement so that unwanted movement is eliminated (this makes it a fixator.
The same muscle may function as an agonist, an antagonist or a synergists as different times.

Question 13

What is muscle tone?

Answer 13

Muscle tone is the maintaining of partially contracted skeletal muscles. It holds many of our body parts in position. For example, the head is held up by partial contraction of the neck muscles. When they fall asleep, their head drills due to loss of muscle tone.
Posture also depends on muscle tone.