Sports, Exercise and Health Science · B.1 Generating movement in the body

SEB.1.3 — Muscular function

Sports, Exercise and Health Science · SL / HL · syllabus-mapped notes

1. SEB.1.3.1

   Types of muscular contraction

   The body uses different types of muscular contractions to create movement and stability. Each type of contraction has a different function.

2. SEB.1.3.1.1

   Acetylcholine

   Acetylcholine is a neurotransmitter stimulating skeletal muscle contraction.

3. SEB.1.3.1.2

   Motor units and the all-or-none principle

   Muscles are organized in functional groupings called motor units that contract using the all-or-none principle.

4. SEB.1.3.1.3

   ATP in the muscle cell

   Muscular contraction requires the metabolism of ATP within the muscle cells.

5. SEB.1.3.1.4

   Types I, IIa and IIx

   Motor units are differentiated by fibre type and neuron diameter: types I, IIa and IIx. Their recruitment patterns vary depending on the activity.

6. SEB.1.3.1.5

   Hypertrophy, atrophy and recruitment

   Hypertrophy and atrophy of muscle can cause alterations in a motor unit recruitment pattern.

7. SEB.1.3.1.6

   The four types of contraction

   Contractions can be described in four different ways: isometric, isotonic concentric, isotonic eccentric and isokinetic.

8. SEB.1.3.1.7

   Agonist, antagonist and reciprocal inhibition

   Muscles usually function in pairs, and act with reciprocal inhibition: their pairings are agonist and antagonist.

9. SEB.1.3.2

   The sliding filament theory

   The sliding filament theory describes the interaction between myofilaments and the molecules responsible for sarcomere or muscle contraction.

10. SEB.1.3.2.1

    The roles of the five molecules

    Calcium, ATP and the proteins actin, myosin, troponin and tropomyosin have specific roles.