The Muscular System

Name the functions of the muscles

Produce movement, maintain postural tone, aid in the production of heat and temp control

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How to muscles produce movement?

Some contract to product movement, pulling on bones. Others stabilise joints when the muscles pull the bones, working together. Muscles also move some body fluids like lymph, blood, and urine

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How to muscles maintain postural tone?

Some muscle fibres resist movement and create slight tension, enabling us to stand upright. Without posture we wouldn't be able to hold normal body positions. Muscle tendons also surround, protect, and stabilise joints, which stabilises body position

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How do muscles aid in temp control and producing heat?

Skeletal muscles create heat as a by product when they contract. It is used to control normal body temp. Muscles help temp control with shivering and contracting blood capillaries

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Name the muscle types

Skeletal, Cardiac, Smooth/involuntary

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Skeletal: describe, location example, and it's function

Striated, long & cylindrical or circular; strengthened & reinforced by connective tissue; have tendons. It is attached to bones, skin, or other muscle. Enables movement of bones, moves blood & lymph, produces heat, maintains posture.

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Cardiac: : describe, location example, and it's function

Striated, involuntary, arranged in spiral-shaped bundles of branching cells. It is in the walls of the heart. It pumps blood around the body and helps regulate blood pressure.

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Smooth/Involuntary: : describe, location example, and it's function

non-striated (smooth), spindle shaped, involuntary. It forms the wall of the stomach, intestines, bladder, uterus, and in all blood vessels. It moves substances through the various tracts in the body

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What gives the striated appearance in skeletal muscle?

Within the muscles there are long fibres made of multi-nucleated cells. Each finer contains many threadlike fibres called myofibrils. These are alternately striped light and dark bands which give voluntary muscles their striated appearance

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Describe what the endomysium and fascicle are.

Skeletal muscles fibres are surrounded by a membrane called the endomysium. The fibers are bound together to form a bundle of fascicle.

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Describe what the perimysium and epimysium are

(skeletal again) The membrane surrounding fascicle bundles is called the perimysium. The fascicles form a larger bundle, surrounded by a membrane called the epimysium (fascia) - ultimately forms an individual muscle

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How do the voluntary muscles receive signals to move?

Impulses from motor neuron's.

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What are 'points of attachment' known as?

Origin & Insertion.

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Do muscles work from origin or insertion?

From insertion to origin.

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Does cardiac muscle have striations?

Yes

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What does cardiac muscle consist of?

short cylindrical branched fibres, with a centrally placed nucleus. Has no sheath.

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What causes the contractions in the cardiac muscle?

It is controlled why nerves which quicken or slow the action.

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Which type of muscle is strongest in the human body?

Cardiac.

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What is another name for smooth muscle?

Involuntary.

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Where can smooth muscle be found?

Stomach lining, intestines, bladder, bowels, uterus, and blood vessels

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Describe smooth muscle's appearance

spindle shaped cells, each with a nucleus. No striations, no sheath. Bund together with connective tissue.

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What happens when smooth muscle stretches and shortens?

It is able to do so whilst maintaining its contractile function

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What causes smooth muscle to stretch or relax?

nerve impulses, stretching, or hormones.

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What are myofibrils?

small fibres within the long cylindrical fibres in muscles.

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What do myofibrils cause? Why?

The striated appearance of muscles. The acting and myosin filaments within overlap and create the striation.

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Describe where myofibrils are in the muscle.

Myofibrils contain 2 protein filaments, which lie side by side, and are arranged into sections along the muscle (not all the way down).

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What is actin

The thinner filaments in myofibrils.

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What are myosin

The thicker filaments in myofibrils.

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How are actin and myosin involved in contraction of muscles?

when a muscle contracts, it shortens and thickens. This is because the actin filaments slide in between the myosin filaments. They slide back out again when the muscle relaxes and resumes its original shape.

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In which ways are muscles attached to the body?

tendons, ligaments, fascia

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Describe tendons, and what is their primary role? Give an example.

Tough, fibrous bands or cords. Do not stretch or contract = not elastic. Despite their great strength, they can be susceptible to injury. Primary role is to hold muscle to bone. Example: Achilles tendon

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Describe ligaments, and what is their primary role? Describe a common injury to a ligament

Strong, fibrous, elastic, cord-like tissue. Allows good freedom of movement as they are pliant and flexible. Primary role is to attach bone to bone and help keep them in place; establish the joints. Common injury: sprain.

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Describe fascia, and what is the primary role?

Fibrous connective tissue that envelopes some muscles, forming partitions for others. It packages, supports, and envelopes the bodies organs. Separates different muscles, allowing them to glide smoothly. Play a key role in maintaining muscle health

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Generally, the end of the muscle closest to the body is called the ?

origin

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Generally, the end of the muscle furthest from the body is called the ?

insertion

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Describe the origin attachment

fixed end of a muscle; barely moves during a muscle action. Often shorter & broader, & attached over a large area. The place where a muscle starts.

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Describe the insertion attachment

the moving end of a muscle. The point to which the force of the muscle is directed. Muscles work from the insertion to the origin.

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What does contractibility mean?

the capacity of the muscle to shorten and thicken

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What does extensibility mean?

the ability to stretch when the muscle fibres relax

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What does elasticity mean?

the ability you return to its original shape after contraction

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What does irritability mean (muscles)?

the response to stimuli provided by nerve impulses

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What do agonist and antagonist mean?

Agonist: the contracting muscle. Antagonist: the opposing, relaxing muscle

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Name the two types of contractions?

Isometric and isotonic

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What is an isometric contraction?

when the muscle moves without actually moving. When the muscle contracts its length stays the same; tension increases = an attempt to overcome an opposing force, eg pushing a wall

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What is isotonic contraction?

the muscle contracts and moves. The length changes, tension remains constant or develops = overcome the opposing force, eg lifting a cup and lowering it.

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How many types of isotonic contractions are there?

two

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Name and describe the isotonic contractions.

Concentric: tension remains the same as the muscle shortens or contracts (lifting a weight). Eccentric: tension remains the same as the muscle lengthens or elongates (lowering a weight)

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What is a muscles ability to contract affected by? (7 factors)

energy available; strength of the stimulus from the motor nerve; time muscle has been contracting; blood supply, o2, and nutrients; presence of waste like urea & lactic acid; strength of inhibitory nerve supply; muscle temp.

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Where do muscles receive their food and oxygen from?

Arterial arteries

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Where is lactic acid excreted?

into the venous blood stream

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What is needed to create energy in muscles?

Glucose and oxygen

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What happens in the case of muscle fatigue?

Waste products, such as lactic acid and carbon dioxide, build up causing stiffness and pain.

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How can massages help with muscle fatigue?

Massage will bring fresh blood with oxygen and nutrients to the muscles, and encourage the removal of waste products such as lactic acid, urea, and co2, allowing the muscle to work properly again.

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Name some benefits of massage on muscles

Brings fresh blood to the muscle; help relieve pain, stiffness and fatigue; can assist the breakdown of fibrositic nodules (knots); increase muscle tone; delays wasting away of muscles

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What are fibrositic nodules?

'knots'. These develop deep within a muscle because of tension, injury, or poor posture. Common in the trapezius area.

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What is the part of the muscle inbetween the origin and the insertion?

the belly.

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What is a sarcomere? What is it composed of?

A sarcomere is the basic contractile unit of muscle fiber. Each sarcomere is composed of two main protein filaments—actin and myosin—which are the active structures responsible for muscular contraction.

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The Muscular System

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