Module 4 Responding to the environment 2.4.7 Coordinated movement

Learning Objectives Success Criteria To understand how movement is coordinated Identify parts of a joint (Grade E - D) Describe how coordinated movement requires action of skeletal muscle about joints, with reference to the elbow joint (Grade C –B) Compare and contrast synapses and neuromuscular junction (Grade B – A) 2

Starter Describe the differences between the CNS and the peripheral nervous system (4 marks)

Coordinated movement CNS coordinates muscle movement, receives sensory info. and decides what responses is required. If a response is needed, the CNS sends impulses along the motor neurones to let the skeletal muscles contract. Skeletal muscles are attached to bones by tendons. Ligaments attach bones to other bones, to hold them together. The structure of joints between bones determines movement Ball and socket – allow movement in all directions Gliding joints – wide range of movement Hinge joints – movement in one plane only – elbow. The elbow is an example of a synovial joint. Synovial fluid is a lubricant, to ease this movement.

Antagonistic muscles The best-known example of antagonistic muscles are the biceps and triceps muscles, which articulate the elbow joint. Movement of bones at many joints require a range of actions and is under control of groups of muscles called synergists Muscles cannot push, only pull  work in pairs which oppose each other. Muscles must be attached to incompressible skeleton, which they move.

Control of contraction

Key terms Neuromuscular junction – a specialised synapse occurring at the end of a neurone where it meets the muscle fibre. Acetylcholine is released after depolarisation stimulating contraction of the muscle fibre. Sarcolemma – muscle fibre cell membrane Sarcoplasm – muscle cell cytoplasm Transverse (T) tubules – invaginated sections of sarcolemma sticking into the sarcoplasm. Spread electrical impulses through the sarcoplasm. Sarcoplasmic Reticulum – network of internal menbranes running through sarcoplasm . Stores and releases calcium ions for muscle contraction.

A muscle fibre is made up of many myofibrils. Myofibrils are themselves made up of contractile proteins There are two types Thick myofilament is myosin Thin myofilament is actin.

Neuromuscular Junction Impulse from motor neurone causes ACh vesicles to be released into the gap ACh binds to sarcolemma (muscle fibre membrane) Depolarisation travels down tubules Calcium ions released from sarcoplasmic reticulum Calcium ions bind to proteins in muscles causing contraction Acetylcholinesterase breaks down ACh in gap and stops the contraction

Plenary - Compare and Contrast Neuromuscular Junction & Synapse Similarities Differences Neuromuscular Junction Synapse

Compare and Contrast Neuromuscular Junction & Synapse Similarities Differences Neuromuscular Junction Synapse Neurotransmitter in vesicles Vesicles release neurotransmitter into cleft Neurotransmitter diffuses across gap & binds to receptor Neurotransmitter results in depolarisation Enzymes degrade neurotransmitter Neurone to sarcomere Postsynaptic simulation leads to depolarisation of sarcolemma End plate has appearance of microvilli Neurone to neurone Postsynaptic simulation leads to AP in postsynaptic neurone Synaptic knob is smooth and rounded

Learning Objectives Success Criteria To understand how movement is coordinated Identify parts of a joint (Grade E - D) Describe how coordinated movement requires action of skeletal muscle about joints, with reference to the elbow joint (Grade C –B) Compare and contrast synapses and neuromuscular junction (Grade B – A) 15