Module 4 Responding to the environment 2.4.8 Three types of muscle

Learning Objectives Success Criteria To understand the three types of muscle Identify 3 types of muscle and where they are found (Grade E - D) Outline the structural differences between each type of muscle (Grade C –B) Explain the structural differences according to function between all 3 muscle types (Grade B – A) 2

Starter Complete exam question

Starter - PA Q4 june 2010

Strength of contraction Depending on e.g. how hard you want to grasp something Brain controls this Many motor neurones controls a single muscle Each branches to a neuromuscular junction causing contraction of a group of muscles (motor unit) More muscles = greater force (gradation of response) Read section – Investigating contraction in isolated muscles page 233 – Draw figure 4

Impulses, twitches, summation and tetanus a) Shows individual action potentials causing individual contractions or twitches. The period in between contractions is the refractory period. Increase in stimulus can cause increase in contraction. b) Shows repeated impulses – leading to enhanced contraction. This is called summation c) Shows a series of quick impulses leading to a state of maximum contraction called tetanus. The muscle would eventually fatigue.

FACTS Your Body has over 600 muscles Muscle contracts to move bones and body parts Muscle makes up approx half your body weight Three different types of Muscle

Control Mechanisms The Nervous System Autonomic Nervous System Heart (cardiac) Involuntary (Smooth) Central nervous System Voluntary (Skeletal/striated)

Heart/Cardiac Muscle Built in Pacemaker – Sino-atrial node Heartbeat is involuntary Influenced by many factors – Such as? Sympathetic innervation speeds up heart rate, Parasympathetic slows it down Myogenic Intercalated discs – cell membranes fused together resulting in gap junctions allowing rapid ion passage Contracts powerfully, without fatigue

Involuntary (Smooth) Muscle Autonomic nervous control Spindle shaped muscle fibres Slow contraction, tires very slowly Found in visceral organs (Hollow organs) Name three locations where you would find smooth muscle? Organs, arteries, iris, intestine

Voluntary (skeletal) Muscle Attached to the skeleton Provides movement and stability Striated in appearance Many nuclei in each fibre Many mitochondria Contracts quickly and powerfully, tires quickly

Voluntary (skeletal) Muscle is attached to bones by tendons REMEMBER Ligaments -Bone to Bone Tendons – Muscle to Bone

Structure of Voluntary (Skeletal) Muscle Made up of thousands of fibres Inside these fibres – Myofibrils Within these Myofibrils muscle contraction takes place

3 Muscle types Get into groups of 3 and each one research a muscle type and feedback Complete table

Activity You should now be able to complete the following table Muscle Type Muscle Structure Primary Function of the muscle Control Mechanism Location

Muscle Type Muscle Structure Primary Function of the muscle Control Mechanism Location Heart Striated and Smooth Pumping of heart Hearts automatic nervous system and the ANS In the heart Involuntary Smooth Vital organs Autonomic nervous system (unconsciously) Blood vessels and Visceral organs Skeletal Striated Movement of the body CNS (consciously) Attached to bones

Plenary Q2 Jan 2011

Learning Objectives Success Criteria To understand the three types of muscle Identify 3 types of muscle and where they are found (Grade E - D) Outline the structural differences between each type of muscle (Grade C –B) Explain the structural differences according to function between all 3 muscle types (Grade B – A) 19