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Muscle Movement Kyla Ward


Lesson Objectives Quick Recap of previous work via post-it notes – Standard Look at why muscles move How they move The type of contractions This stuff is pretty complex in parts so feel free to ask any questions at any point!!


To recap……. Can you name the three different muscle fibres? Can you name the three types of muscles? What type of muscle fibre would we use for a marathon?


Note taking and Moodle I know you will all want this on moodle and I will put it there but there are some important things I want you to note down. When you see this‌.

You need to take notes.


I have given out a red card and a green card If I ask the question‌.does everyone understand??? Hold the green card up if you do and the red if you are unsure.


Bit of a background So far we have looked at the major muscles and located them. Now we need to look at how they actually move. Our skeleton will not move unless we contract our muscles to move it.


Who wants to be a Muscle? Which of these forces does a muscle exert? A. Push

C. Pull

B. Gravity

D. None of the above


Who wants to be a Muscle? Which of these forces does a muscle exert? A. Push

C. Pull

B. Gravity

D. None of the above


Who wants to be a Muscle? Which of these forces does a muscle exert? A. Push

C. Pull

B. Gravity

D. None of the above


Good Job!!!!!! The only action our muscles can take is to pull bones in and out of the desired position. When a muscle contracts it is pulling a bone. Muscles Contract when there is a stimulus from your nervous system. i.e. when your brain tells your muscles to move


Strength of the Contraction The strength of the contraction depends on the number of muscle fibres brought into use.

THINK‌‌

Which type of fibre will bring about the strongest contraction?


Activity……. This is an activity which requires some people to become body parts….


Activity 1 What muscle brings about flexion at the elbow??? What tells our muscles to contract??? Where does our Radius move to when it is flexed??? What muscle brings about extension at the elbow???

So… now a few of us are these body parts…lets see what happens when we flex our arm…


Agonistic Muscle Pairs Hopefully, fingers crossed that will have demonstrated to you what is known as an antagonistic muscle pair. As muscles only pull and do not push they have to work in groups to bring about action.


Agonist The muscle that shortens to move a joint is called the agonist or prime mover. In our flexion example this was the bicep. This muscle (agonist) has the main responsibility for movement taking place. It is the CONTRACTING muscle.


Is everyone with us so far???


Antagonist The antagonistic muscle is the muscle that is relaxing while the agonist is working. It is responsible for the opposite action. In our example the opposite action was flexion. If it did not relax when the agonist was working we couldn’t move our arm WHY???


Main Points Then Agonistic muscles work in opposite ways to bring about a contraction. Quick question then‌.. If the hamstrings contract to flex the lower leg what is the antagonist and what is it doing while the hamstrings are contracting??


Just in case we are still a bit unsure


Think about this‌ Hold your arms out to the side How many muscles are working right now? Perform a bicep curl with your arms remaining out. How many muscles are you working now? ANSWER: More than you think!


Other working muscles The Synergists These are the muscles that aid the agonist while it is working. These muscles aid the agonist by preventing any unwanted movement of other muscles i.e. they are used to stabilize


Fixator These are similar to synergists as they provide stability for the agonists to work. They prevent unwanted movement throughout out the rest of body. It stabilizes the body to enable a firm working base for the agonist.


Muscle Roles In any movement the muscles will play 1 of 4 roles: Agonist Antagonist Fixator Synagist


That time again!!! How are we doing?


Activity‌ So that we can visualise the 4 roles I need 4 volunteers‌

4


Activity‌ Can you identify the agonist, antagonist, fixator(s) and synagist(s) in‌ A push up (pushing up) A squat (coming up) A sit up (sitting up)


Push up (pushing up) Agonist: Pectorals Antagonist: Bicep Fixator: Deltoids Synagist: Tricep


Squat (coming up) Agonist: Quads Antagonist: Hamstrings Fixators: Multifidus (spine muscles) Synagists: Glute Max


Sit Up (sitting up) Agonist: Rectus Abdominus Antagonist: Multifidus (spine muscles) Fixators: Quads and Hams Synagists: Illiopsoas (hip flexor muscles)


So that was the antagonistic muscle system‌.. Moving on


Get out those cards‌. Has it sunk in?


Muscle Contractions There are 3 main types of muscle contractions. Isometric Concentric Eccentric


Isometric You have already met this type of contraction in ‘training and fitness’ Can you remember what it means? This is where the muscle is contracting but it is not shortening. Usually found when a muscle is engaged in holding a static position


Concentric shortening of the muscle due to contraction. Our bicep example earlier was an example of concentric contraction Concentric – Coming

up


Eccentric Lengthening the muscle during contraction

Eccentric – Downward

phase


See what you remember‌ Quickly write down a definition for each of these terms.


Hows it going???


MOVING ON…… This is the tough stuff so now would be a good time to listen up carefully


Sliding Filament Theory The structure of a muscle fibre is very complex but we must look at each part in order to fully understand the ‘sliding filament theory’


Muscle Fibre Info.. An individual muscle cell is called a fibre. A muscle fibre is enclosed by a plasma membrane called the sarcolemma. The cytoplasm of a muscle fibre is called the sarcoplasm.


Muscle Fibres Continued.. Each muscle fibre contains hundreds to several thousand Myofibril. These are the contractile elements of the skeletal muscle.

Muscle Fibre


Sarcomere The sarcomere is the smallest functional unit of a muscle. Sarcomeres are joined end to end at the Z disks.


The Big Picture Then


Is everyone clear so far??


Activity You have until the end of the song to write down the answers to the following. Where are sarcomeres joined? What are muscle cells known as? What is the contractile element of the skeletal muscle.


Sarcomere cont’d‌.. The myofibrils are composed of lots of these sarcomeres that are joined at the z disks. Therefore, we can say that the sarcomere is what is found between each Z disk.


This is includes, in this order.. An I band (light Zone) An A band (dark zone) An H zone (in the middle of the A band) The rest of the A band A second I band


Sarcomere


Filaments If you looked at the myofibrils under the microscope you would see two filaments. A thin one called Actin A thick one called Myosin


Name the difference between actin and myosin


Actin and Myosin These are both protein strands. Actin has one of its ends inserted into the Z disk. At the end of one of the strands of protein strands is a myosin head.


Its getting tougher…Are we all ok??


Actin Actin is not found alone, it is also by two other protein molecules called:Tropomyosin And Troponin


Tropomyosin and Troponin The tropomyosin twists round the actin strands. The troponin is a protein attached at regular intervals on the actin and the tropomyosin


Sliding Filament Theory How do muscles fibres shorten? – The explanation to this is known as the sliding filament theory. We have looked at the components now we need to see how they work together to create movement.


An overview


Sliding Filament Theory Nerve impulses arrive at motor end plates in the muscle. Calcium ions (ca++) are then released. The ca++ bind on to the troponin on the thin actin filaments. This binding forces the troponin to come loose revealing the binding sites. The thick myosin filament heads then grip on to the actin thin filament binding sites.


The thin and thick myofilaments are now locked The thick myosin filaments drag the thin actin filaments inwards


Skeletal Muscle Contraction This shortens the sarcomere by bringing in the Z lines The H zone disappears as the filaments come together The I band also disappears as does the A band The length of the filaments does not change


Skeletal Muscle Contraction Due to the Z lines being drawn closer together and the shortening of the sarcomere the whole muscle shortens and contracts Each time a thick myosin filament head draws in an actin thin filament hundreds of other myosin heads are binding on to actin sites throughout the whole myofibril.


Energy Energy is required to make the muscle contract. This is in the form of ATP. The Myosin head has a site for ATP to bid to. The enzyme adenosine triphosphatease (ATPase) (located in the myosin head) splits the ATP to release energy which is used to bind the myosin head to the actin site.


Last Time‌ Is anyone lost?


Just to make sure we are absolutely clear‌ In pairs take it in turns to describe exactly what is happening to make a muscle contract.


See You Next Time….


Muscle Movement