Muscles and the Muscular System

Objectives; Look at the 3 different types of muscle. Take a close look at muscle fibre. Look at the major muscles in the body.

Introduction The muscular system works with the skeletal system to produce movement of the body. The nervous system also works in conjunction with the muscular system to initiate movement in the muscles. The muscular system can be divided into 3 parts: smooth, cardiac and skeletal.

Types of muscle Smooth muscle Involuntary muscle Cardiac muscle The Heart Involuntary muscle Skeletal muscle Muscle attached to the skeleton

Smooth Muscle Smooth muscle are also know as involuntary muscle. This is because we do not control them consciously.

How Smooth muscles work. Examples of smooth muscle can be found in the digestive system, circulatory system and urinary system. In these systems the smooth muscles work in similar ways. They use peristaltic action (muscles contracting consecutively rather than at the same time )making the muscle contract in a wavelike action – this is how food is passed through the digestive system and how arteries and veins walls expand and contract.

Cardiac Muscle As its name implies Cardiac muscle refers to the unique muscle tissue and myocardium (pumps blood around the body) that makes up the heart.

How Cardiac Muscle works Cardiac muscle is also an involuntary muscle. The heart is triggered by its own nerve supply via the sino-atrial node which sends a nervous impulse through consecutive cells. The fibres of the heart will contract involuntarily around 60 – 80 times a minute to help pump blood around the body.

Skeletal Muscle Any muscle that is attached to the skeleton (via tendons) is skeletal muscle.

How skeletal Muscle works Unlike smooth and cardiac muscle skeletal muscle is voluntary and we consciously use it to produce movement. Due to the way the rows of fibres in skeletal muscles look it is also called striated or stripped. The coordinated contractions of skeletal muscle allow us to move smoothly and produce sports skills. Over 700 skeletal muscles make up around 40 % of our body weight.

Functions of skeletal muscle; Producing movement. Maintaining body posture. Generating heat to keep us warm. Storage of glycogen for energy.

Types of Skeletal Muscle Fibre 1.Slow twitch fibres Red in colour and have a good blood supply They have a dense network of blood vessels which makes them suitable for endurance exercise as they are slow to fatigue. Slow twitch fibres also contain mitochondria which are energy producing organelles within cells.

2.Fast twitch fibres Whiter in colour. Contract quickly so are thick in size. They have a poor blood supply which means they will fatigue quickly due to low oxygen supply. Fast twitch fibres are used in powerful explosive exercise i.e. sprinting Fast twitch fibres come in two types: 2a and 2b 2b is used when the muscles are close to their maximum intensity 2a work at slightly lower intensity but higher then slow twitch fibres; For example a 100m sprinter will use 2b while a 400m sprinter will use 2a.

Major Muscles – Upper body Trapeziuos Upper back Intersects with clavical and scapula. Obliques; internal retus and external Intersects withsternum and ilium Lower back

Pectoralis Intersect with with clavicle and sternum Chest

Deltoid; posterior, anterior and middle Intersects with clavicle and scapula Shoulder Triceps brachii Intersects with humerous and scapula Upper arm Biceps brachii Intersects with scapula Upper arm

Major muscles – Lower body Hamstring group Bicep femorious, semitendinosus and semimembransosus Intersects with tibia and fibia

Quadriceps group; Rectus femoris, vastus lateralis, vastus intermedius and vastus medialis Intersects with tibia Gastrocnemius and Soleus Intersect with femur and tibia.

Task 1 Describe, in detail, the difference between the three types of muscle and the difference between the two types of muscle fibre.