11.2 MovementAnimal Physiology (AHL)

Kinesiology: The study of ____________________________ of the human body

What happens when somebody moves? Your brain sends an impulse (an action potential) through a nerve to a muscle to tell

it to contract. Muscles are connected to bones by __________________. When a muscle __________________, it will move the bone.

Bones Rigid structures for anchoring muscles They contain several different tissues and therefore are

organs. Functions :

Provide a hard framework to __________________ the body

__________________ vulnerable softer tissues and organs Act as levers so that body movement can occur Form blood cells in bone marrow Storage of minerals (ex: calcium and phosphorus)

The Human Skeleton: Adult humans have bones

o 26 bones in your o 12 pairs of o are not considered to be bones.

Exoskeletons Some animals do not have bones but have exoskeletons that provide a similar

function. Exoskeletons are external skeletons that surround and protect most of the body

surface of crustaceans, insects, and spiders

Levers Bones and exoskeletons facilitate movement by _______________________ muscles and

acting as a _________________. Muscles are attached to the _____________ of bones and the ________________ of

exoskeletons A lever is a rigid rod (the bone) that turns about a _____________ (usually a joint). Levers change the size and direction of forces.

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Components of Levers• Lever Arm

• • Effort Force

• • Fulcrum (pivot point)

• • Load

• The body part that is moved (as a result of the Resultant Force)•

Types of Levers

First Class Lever: The fulcrum is between When a force is applied, the resultant force causes the load to move up. E.g.

Second Class Lever: The load is between There is a because less for is required. E.g.

Third Class Lever: The effort force is between No mechanical advantage – more force is required to lift the load. E.g.

Muscles and Tendons Skeletal Muscles are attached to bones

Tendons are what attach muscles to bones

Tendons are cords of dense connective tissue

Muscles provide the force necessary for movement by shortening the length of their

fibres.

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Antagonistic Muscle Action Muscles work in antagonistic pairs to achieve movement

When one muscle contracts, the other relaxes

When the biceps contract, ____________________________________________________________________________________________________________________________________e

When the triceps contract, _______________________________________________________ _____________________________________________________________________________, it

causes the bones to straighten. The bicep

Antagonistic Muscle Pairs in Insect Legs

Insect legs also have antagonistic muscles to flex and extend the joint by:

1.2.

When the grasshopper prepares to jump:FLEXING:

The flexor muscles will contract bringing the tibia and tarsus in a “Z” position. The extensor muscles are relaxed.

EXTENDING: The extensor muscles contract strongly, causing the tibia to extend, making the

insect jump.

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Joint Also called an articulation or arthrosis The point where 2 or more bones contact one another Joints cause mobility and hold the body together Most joints include:

Bones Ligaments Muscles

Tendons nerves

Annotate (label) a Human Elbow Joint:

Elbow Joint Part

Description

Spongy Bone

Cartilage

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Joint Capsule

Synovial Fluid

Synovial Membrane

Ligaments

Biceps

Triceps

Humerus

Radius

Ulna

The elbow joint is called a ___________________________ because of the presence of the synovial cavity.

There is a rich supply of blood to joints. If blood vessels supplying the joint gets damaged and there is local bleeding, it may

result in swelling of the area

Classes of Joints:1. Synovial Joints

Have a lubricating synovial cavity Provides lots of

2. Cartilaginous Joints Join bones with cartilage. E.g.

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3. Fibrous Joints Joins bones with connective tissue (collagen) E.g.

Joint TermsFlex and Extend

Example: Movement that moves your leg back and forth (like a pendulum) Flexion = decrease the angle between the connecting bones Extension = increase the angle between the connection bones

Abduction and adduction Example: Moving your leg sideways (away from the center of the body)

Abduction = bones moves away from body’s midline Adduction = bones move toward body’s midline

Rotation Bone moves along its own longitudinal axis

Hinge Joints

Provides an opening-and-closing type of movement like the action of a door This movement is in one direction – flex and extend Example: the elbow joint, the knee joint

Ball and Socket Joints Allows for movement in several directions

Flex and extend Abduction and adduction Rotational movement

Example: Hip Joint

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the head of the femur is ball shape and fits into a cup like depression of the hip bone

Joints and MovementThe structure of the joint (including the joint capsule and ligaments) determine the movements that are possible.

Knee Joint Hip Joint

Type Synovial JointHinge Joint

Synovial JointBall and Socket

Role Involved in movement of the leg and required for walking

Involved in the movement of the leg and required for walking

Possible Motions

Flex and ExtendSmall amount of rotation

Flex and ExtendAbduction and AdductionRotation

Range of Movement

Movement in one direction Movement in many directions (multiaxial)

Types of Muscle Human body has 3 types of muscles:

1. _______________________________________________________________________2. _______________________________________________________________________3. _______________________________________________________________________

Skeletal Muscle/Striated Muscle Skeletal muscle is characterized by a hierarchy of smaller and smaller units. A skeletal muscle consists of a _______________ of long fibres running parallel to the

length of the muscle. Each __________________________ is a ___________________________ with multiple nuclei,

reflecting its formation by fusion of many embryonic cells. The arrangement of proteins within muscle fibres creates a banded appearance of

stripes under a microscope, which is why it is called striated muscle. A muscle fibre is itself a bundle of smaller _________________________ arranged

longitudinally.

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Parts of a Muscle FibreEach muscle cell was originally many cells fused together, which is why a muscle cell has many nuclei.

Sarcolemma: ___________________________________________________________________ Sarcoplasm: __________________________________________________________________muscle

Within the sarcoplasm there are multiple mitochondria for ATP production (because muscle contractions require a lot of energy)

Sarcoplasmic Reticulum: membrane found within the sarcoplasm (similar to the ER) Stores and releases _________________________ into the sarcoplasm which will

trigger a _________________________________

Myofibrils: __________________________________________________________________________ Create the striated (striped) pattern of light and dark skeletal muscles Composed of two types of myofilaments:

1. Thin Filaments: _________________________________________________________2. Thick Filaments: ________________________________________________________

Sarcomere: The basic ________________________________________of the muscle (a segment of a myofibril)

Sarcomere A sarcomere is found between two ____________ Thin actin filaments form the ___________

They are attached to the Z line and project toward the centre of the sarcomere

Thick myosin filaments are found in the __________

In the _______________, myosin and actin overlap

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The thin filaments do not extend completely across the sarcomere, so the gray _____________ in the centre of the A band contains only thick filaments.

Muscle Contraction We can explain much of what happens during

contraction of a whole muscle by focusing on a single muscle fibre

According to the Sliding Filament Model, myosin-actin interactions underlie muscle fibre contraction.

Myofilaments – Myosin Thick Filaments

Thick filaments contain several myosin molecules bundled together

Each myosin molecule consists of a long “__________” region and a globular “________” region extending to the side.

The tail adheres to the tails of other myosin molecules that form the ________________________

The head binds to _____________, which powers muscle contractions

H Zone: filaments have no heads or tails

Myofilaments – Actin Thin Filaments Thin filaments contain strands of actin and two strands of regulatory proteins:

1. ___________________________________2. ___________________________________

Two strands of tropomyosin wind around the actin filament covering the binding site for the myosin hooks.

This prevents the muscle from contracting.

Sarcomere Arrangement

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Sliding Filament Model of Muscle Contraction

Neither thin nor thick filaments change in length when the sarcomere shortens.

Filaments slide past each other longitudinally producing more overlap between the thin and thick filaments.

A) Relaxed Muscle FibreIn a relaxed muscle fibre, the I bands and H zone are relatively ___________.(B) Contracting Muscle Fibre

During contraction, the thick and thin filaments slide past each other, reducing the width of the I bands and H zone and ________________________ the sarcomere.

(C) Fully Contracted Muscle Fibre In a fully contracted muscle fibre, the sarcomere is shorter still. The thin filaments

overlap, eliminating the _________________. The _______________ disappear as the ends of the thick filaments contact the Z lines.

Recap: Sliding Filament Theory Actin and myosin slide over each other to make the muscle shorter (actin and myosin

stay the same size!) Little “hooks” on the myosin filaments attach to the actin and pull them closer to the

centre of the sarcomere. This shortens the sarcomere and the overall length of the muscle fibre – muscle

contraction! Myosin then releases the actin and repeats the hooking and pulling action further

down the actin. This is done with ATP energy (from mitochondria!)

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As the filaments slide over each other, the H bands disappears and the I band shortens.

Which of the following diagrams shows a relaxed muscle and which shows a contracting muscle?

The Role of Calcium & Regulatory Proteins in Muscle Contraction

A skeletal muscle fibre contracts only when stimulated by a motor neuron. When the muscle fibre is at rest, the myosin binding sites on the thin filament are

___________________ by regulatory protein ______________________. For the muscle fibre to contract, those binding sites must be ______________________. This is achieved when an action potential arrives at the muscle and causes the

sarcoplasmic reticulum to release calcium ions (Ca2+) into the sarcoplasm. The Ca2+ bind to the troponin complex, which controls the position of tropomyosin on

the thin filament. Calcium binding rearranges the tropomyosin-troponin complex, exposing the myosin

binding sites on the thin filament. The myosin head is bound to ATP already and is in its low-energy configuration. The myosin head will hydrolyze ATP into ADP and Pi (but will still be attached to

myosin head) and is in its high-energy configuration. The myosin head can now bind to the actin binding sites on

the thin filament, forming a _________________ The ADP and Pi dissociate from the cross-bridge and the

myosin head bends, pulling actin filaments toward the M line. This is called the _____________________. It causes the myofilaments to slide over each thus the muscle fibre contracts.

The cross bridge is broken when a new molecule of ATP binds to the myosin head.

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The process may repeat with the heads attaching to binding sites further along the actin filament.

Muscle Relaxation Contraction cycles will continue as long as ATP is available and Ca2+ is present in the

sarcoplasm When the nerve impulse stops, Ca2+ move back into the vesicle of the sarcoplasmic

reticulum by active transport This causes the binding sites on the actin to be covered again (so myosin cannot

bind) The muscle will relax.

Cardiac Muscle Cells (p 685) The structure of cardiac muscle cells allows for propagation of stimuli through the

heart wall. Remember, cardiac muscle tissue is unique. It is also striated in appearance, and the arrangement of myofilaments is similar to

skeletal muscle.

How do they differ from skeletal muscle fibres?

• Cardiac muscle cells are • They have only per cell.• Cardiac muscle contraction is not under voluntary control • Many cardiac muscle cells contract even in the absence of stimulation by nerves for

the entire life of the organism!

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The cells are ______________________ There is a specialized junction called an ______________________________where the end

of one cell meets the end of another cell The intercalated disc consists of a double membrane containing

________________________ which are channels that provide a connection between the cytoplasm of adjacent cells.

This allows for the rapid movement of ions from one cardiac cell to the next, with low electrical resistance.

So, their Y-shape and gap junctions allows them to be electrically connected This means a wave of depolarization can easily pass form one cell to a network of

other cells leading to synchronization of muscle contraction allowing for both atria and both ventricles to contract smultaneously as if it was one large cell.

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