Page 52 - PRE-U STPM BIOLOGY TERM 1

Biology Term 1 STPM Chapter 2 Structure of Cells and Organelles

6. Neuroglia are supporting cells closely associated with neurones. Exam Tips
They include the Schwann cell and the supporting cells in the Remember the general
brain and spinal cord. Schwann cell forms the myelin sheath that structure, including
insulates the axon or dendron which enables impulse to travel faster. drawings of motor, sensory
Other neuroglia supply nutrients to neurones, remove wastes from and associative neurones.
neurones, guide axon migration and provide immune functions.

Muscle tissue Summary 2
1. Muscle tissue is a group of cells or multinucleated syncytial tissue
Muscle tissue
which can contract. 1. Striated muscle
• Multinucleated fibres for
2. Muscles are divided into striated, cardiac and smooth muscles. movement in bones
(a) Striated muscle 2. Cardiac muscle
(i) Striated muscle also known as skeletal or voluntary muscle, • Branched fibres for
pumping in heart wall
consists of a bundle of muscle fibres attached to the bone 3. Smooth muscle
by tendons at both ends. Contraction of striated muscle • Non-striated fibres for
produces movement of the bone at the joints as well as movement in intestinal
wall
certain parts of the body.
Tendon Connective tissue One muscle fibre

Bone Complete muscle Bundle of muscle fibres
Figure 2.50 Striated muscle
(ii) Each fibre is supplied with a motor nerve through a special
neuro-muscular synapse called the end plate. Contraction
is a result of impulse sent to the muscle fibre. It is under our
conscious control. Each fibre consists of many myofibrils
as shown in Figure 2.51.

Nucleus

Sarcomere

Myofibril

A band I band

Figure 2.51 Part of a muscle fibre
(iii) Within each myofibril, there is an alternating dark and
light bands that produce striations seen under light
microscope. Dark band (A band) consists of thick myosin

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