Functional Anatomy Quiz 1 Part 2

Wear to Articular Cartilage

Interfacial Wear

• Adhesion: fragments stick to each other

• Abrasion: soft material is scraped by a harder one

Fatigue Wear

• Tensile failure of collagen fibres

• PG washout: degradation of these fibres due to excessive loads

• Impact Loading: high stress too quickly does not allow fluid distribution to take place

Skeletal Muscle

Striated and Voluntary

Cardiac Muscle

Striated and Autonomous

Smooth Muscle

Smooth and Autonomous

Sarcoplasmic Reticulum

• SR surrounds each myofibril

• responsible for storing and regulating calcium

Muscle Layers

Myofilaments

Excitation - Contraction Coupling

Excitation

Step 1: Action Potential

Step 2: Diffusion

Step 3: Depolarisation

Step 4: Opening of Binding Sites

Excitation - Contraction Coupling

Contraction

Step 5: Cross Bridge

Step 6: Movement

Step 7: Release

Step 8: Preparation

Excitation - Contraction Coupling Notes

Notes

Step 9: The Action Potential

Step 10: Importance of Calcium

Muscle Length-Tension Relationship

• If the length is too long, there is minimal overlap between myosin and actin

• If the length is too short, actin becomes overlapped and functionally polarised in opposite directions

Muscle Load-Velocity Relationship

- velocity of a concentrically shortening muscle is inversely related to the external load applied

• When the load is less than the force, a concentric contraction will occur

• When the load is equal to the force, an isometric contraction will occur

• When the load is greater than the force, an eccentric contraction will occur

Muscle Force-Time Relationship

• The longer the contraction time, the greater the force

• Muscle tension is influenced by the time for the tension to transmit through parallel elastic components to the tendon

Muscle Architecture

• Muscle fibre arrangements

• Fascicles attach obliquely to a central tendon called the aponeuroses

• Muscles with long fibres and small cross-sectional areas are designed to produce movement and velocity (parallel)

• Muscles with short fibres and large cross-sectional areas are designed to produce force (pennnate)

Pararel Muscle Fibre Arrangement

Pennate Muscle Fibre Arrangement

Lifting Phase

• harder

• CONCENTRIC

• SAME AS ACTION

Lowering Phase

• easier

• ECCENTRIC

• OPPOSITE TO ACTION