Download Nerves, Muscles and Movement

Muscles and
Movement
Part 1 and 2
HL Paper 1
and 2
Muscles and Movement – Part 1
Assessment Statement
11.2.1 State the roles of bones, ligaments, muscles, tendons and nerves in human
movement
11.2.2 Label a diagram of the human elbow joint, including cartilage, synovial fluid,
joint capsule, named bones and antagonistic muscles
11.2.3 Outline the functions of the structures in the human elbow joint named in
11.2.2
11.2.4 Compare the movements of the hip joint and knee joint
Movement, or response to stimuli is a characteristic of all living things.
Locomotion
The response needed to move and respond must be instantaneous. The Endocrine System
tends to be slightly slower, so the Nervous System is needed.
In order to move, you need a frame (skeletal system), you need joints, muscles and a
motor to drive all of this, the Nervous System, as we saw earlier.
You need the nerves to signal movement, muscles connected to bones, to act as levers,
tendons to attach to the bones and ligaments to hold the bones together.
In order to move, skeletal muscles are involved. Muscles in the body not attached to
bones are the cardiac muscle and the muscles of the gut and reproductive system.
Nerves (went over previous topic)
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Carry impulses to and from the brain to co-ordinate muscular activity
Motor neuron impulses stimulate the muscles to contract
Nerve impulses control timing and speed of muscular contraction
Muscles
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Contain receptors that send information via sensory neurons to the brain about the
position of the muscle
Contract to bring movement to the joint
Work in muscles pairs on each side of a joint
Muscles have a belly (gaster) and a tendon. Define belly and gaster.
Each muscle has an insertion and an origin. Define origin and insertion.
The biceps inserts on the radius and originates on
the scapula. The triceps inserts on the ulna and
originates on the humerus and the scapula.
Based upon the insertion and origin, you can figure
out what the muscle moves.
Bones
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Bones meet at a joint and act as levers
Different types to joints between bones control the range of movement
Provide rigid anchorage for muscles through tendons
Form blood cells in the bone marrow
Provide a hard framework to support the body
Allow protection of vulnerable softer tissue and organs
Allow for the storage of minerals, especially calcium and phosphorus
Connected by ligaments
Ligaments
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fibrous tissue
run from one bone to another, across joints
connect bones together, and give the joint strength.
The Human Elbow Joint
Draw a diagram of the human elbow joint.
Bones
Humerus – rigid structure for muscles to anchor to.
Ulna – create a fulcrum at joint, insertion for triceps
Radius – insertion point for biceps
Muscles
Biceps – flexor muscle-bends joint and lessens the angle of a joint
Triceps – extensor muscle-straightens joint and increases the angle of the joint
Define Cartilage, Synovial Fluid, Spongy Bone, Band Ligaments and Capsular
Ligaments
Roles in Movement or Locomotion
When the elbow is to move, signals pass along the nerves to the muscle, causing it to
contract. The muscles, connected to the bones by tendons, pull on the bones, using
leverage. The end of the bone will move relative to the amount the muscle has
contracted.
The movement is reversed by the contraction of the muscle on the opposite side of the
bone, or a relaxing of the frontal muscle.
What has to happen to ensure the joint does not go past its ROM?
Comparing and Contrasting Two Joints – the knee and the hip
The knee is similar to the elbow. They are both hinge joints. These joints are freely
movable and are also called diarthrotic joints. The hip is also a diarthrotic joint, but is a
ball and socket joint.
The following compares the hip and knee joint.
Hip Joint
Freely moveable
Angular motion in many directions and
rotational movement
Motions possible are flexion, extension,
abduction, adduction, circumduction and
rotation
Ball-like structure fits into a cup-like
depression called the acetabulum
Knee joint
Freely moveable
Angular motion in one direction
Motions possible are flexion and extension
Convex surface fits into a concave surface
Assignment - 45 marks
1.
Define Antagonist Muscle and Agonist Muscle.
2.
Answer the questions below, utilizing the following instructions. Use the
direction of the movement for each, explain where the muscles must be
located, and explain which is the agonist and antagonist when the movement
occurs. Diagrams might be helpful. Remember to reference if resources are
used. (6 marks)
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(2 marks)
How does a bird fly?
How does an arthropod walk?
How does a human bend its elbow?
3.
What are the three types of levers? Where are they used in the human body?
Give an example of each, stating the joint, bones involved and the type of
lever. (9 marks)
4.
What type of lever are most of the joints in the body? What are the
advantages of using this type of lever and the disadvantages of using this
type of lever? (3 marks)
5.
What are the types of joints we find in our body? What movement is
achieved by each type of joint? What is the ROM of each joint? (15 marks)
6.
Define each of the following movements (6 marks)
a.
b.
c.
d.
e.
f.
Flexion
Extension
Abduction
Adduction
Circumduction
Rotation
7.
What is the axial skeleton? Name one bone, which is part of the axial
skeleton. (2 marks)
8.
What is the appendicular skeleton? Name one bone, which is part of the
appendicular skeleton. (2 marks)
Muscles and Movement – Part 2
Skeletal Muscle Fibers
Assessment Statement
11.2.5
11.2.6
11.2.7
11.2.8
Describe the structure of striated muscle fibres, including the myfibrils
with light and dark bands, mitochondria, the sarcoplasmic reticulum,
nuclei and the sarcolemma
Draw and label a diagram to show the structure of a sarcomere, including
Z lines, actin filaments, myosin filaments with heads, and the resultant
light and dark bands
Explain how skeletal muscle contracts, including the release of calcium
ions from the sarcoplamic reticulum, the formation of cross bridges, the
sliding of actin and myosin filaments and the use of ATP to break cross
bridges and reset the myosin heads
Analyse electron micrographs to find the state of contraction of muscle
fibers
A skeletal muscle is made up of bundles of thousands of muscle fibers, or muscle cells.
The muscle fibers lie parallel to one another and range from 10 to 100 um in diameter.
The typical length is 100 um, but some can be as long as 30 cm.
Each muscle fiber is surrounded by a sarcolemma (sarco – flesh, lemma – sheath). This
is the muscle fiber’s cell membrane.
The muscle fibers are developed from the fusion of smaller cells during development, and
therefore, have many nuclei and mitochondria.
Each muscle fibers contains many myofibrils. The cytoplasm, called sarcoplasm,
contains mitochondria packed between the myofibrils. In between the myofibrils is a
transverse tubular endoplasmic reticulum, called the sarcoplasmic reticulum.
Muscles – Gross (Macro) Structure to Microstructure
Structure and Contraction of Striated Muscle
In the muscle cell, there are thin myofibrils. The fibers cause the typical striated pattern
of skeletal muscles.
In the myofibrils, there are two protein myofilaments called myosin and actin.
The myosin is the thick filament, that appears darker.
The actin is the thin filament, that appears light.
The stripes are caused by the alternating light and dark bands.
Diagram of the electron micrograph
The actin filaments are about 7 nm in diameter and are held together by transverse
bands called Z line. The actin partially overlaps the myosin filaments, which gives
the section a dark appearance. This is called the A band, which is from end to end of
the myosin filament. The area where only myosin is seen is called the H band or
zone. This is between the two Z lines. The entire unit between the two Z lines is
called the sarcomere.
As mentioned before, across the fibers there are transverse tubules, or T – tubules. The
tubules touch the sarcolemma and associated with vesicles which are part of the
sarcoplasmic reticulum. A T-tubule with a pair of vesicles is called a triad.
The vesicles are important. They regulate the movement of calcium ions to and from the
sarcoplasm. The Ca+2 concentration determines the activity of ATPase (which
hydrolyses ATP, releasing energy). This determines the activity of the muscle.
Diagram of a Sarcomere
Contraction of Striated Muscle
When muscles contract, it was discovered that the actin and myosin filaments slide past
one another. The A band, myosin, is the same length in contracted and relaxed
muscles. This lead to the sliding filament theory.
Looking at an electron micrograph, you can tell the difference between the sarcomere that
is contracted and relaxed, based upon the H zone. The smaller the H zone, or clear area,
the more the sarcomere has contracted. Also, the space between the z line and end of
myosin, gets darker as overlap develops.
Look at the following electron micrograph. Is it contracted or not?
The contraction of muscles occurs in a series of steps, sometimes described as a ratchet
mechanism. Lots of ATP is used in the process.
Along the actin filament are binding sites for the heads of the myosin filament. Actin
filaments contain actin as well as tropomyosin and troponin. Tropomyosin forms two
strands which wind around the actin filament, covering the binding site. The
tropomyosin is held in place by the troponin. This is how the actin filament remains at
rest.
The thick filaments are composed of myosin molecules, each with a bulbous head. The
head protrudes from the length of the myosin filament. The head, when the muscle cell
contracts, binds to the site on the actin filament. This is what causes movement of the
filaments, and eventually the movement of the whole muscle.
The contraction of the sarcomere is best described in four steps:
1.
The myofibril is stimulated to contract by the arrival of an action potential. This
triggers the release of calcium ions from the sarcoplasmic reticulum, to surround
the actin molecules. The calcium ions react with the troponin. When the
troponin is activated, it triggers the removal of the blocking molecule,
tropomyosin. The binding sites are now exposed.
2.
Each bulbous head has an ADP and Phosphate group attached to it (called a
charged bulbous head). It reacts with a binding site on the actin molecule beside
it. The phosphate group detaches.
3.
The ADP molecule is then released from the head, and this is a trigger for the
rowing movement of the head. The head tilts 45o and pushes the actin filament
along. This step is called the power stroke and the myofibril contracts.
4.
A molecule of ATP binds to the head. The protein, ATPase, catalyses the
hydrolysis of ATP. The result is ADP and Phosphate is attached to the bulbous
head, and it is said to be charged again. The charged head detaches from the
binding site and straightens.
The cycle of movement repeats itself many times per second, with thousands of heads
working along each myofibril. ATP is used up and the muscle may shorten by about
50% of its relaxed length.
When no more impulses arrive, calcium ions are moved back into the vesicles of the
sarcoplasmic reticulum by active transport. The binding sites are covered by the
tropomysin and the muscle relaxes.
(SEE ATTACHED DIAGRAMS)
Controlled Movements and Posture
Muscles involved in maintaining body posture, like the muscles of the back, use subtle,
delicate movements. They can also move in vigorous actions as well.
Nervous control of muscle contraction may cause the muscle to contract moderately, or
fully, depending on the movement required. The overall length of the sarcomere is
changed according to the movement required.
Extension – Neuro / Muscular Diseases
Multiple Sclerosis
An autoimmune disease, which the myelin sheath is attacked and destroyed. The scars
(scleroses) are what is left. As a result, the nerves do not conduct and connect to the
skeletal muscles properly, causing jerky movements or no movement at all.
Muscular Dystrophy
A degeneration of muscle fibers. As a result, the muscle atrophies and weakens. In one type
of MD, Duchenne MD, there is a protein called dystrophin not present in the sarcolemma of
the cell. This may cause calcium to leak into the sarcoplasm, that may activate and enzyme
that causes the muscle fibers to degenerate.