Exam (elaborations)
Skeletal System
Exam of 38 pages for the course ISC2 CC at ISC2 CC (Skeletal System)
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Skeletal System● It SUPPORTS the organs and tissues of the body. Without this
support they would collapse under their own weight
● It provides PROTECTION for internal organs. For example, the
cranium protects the brain; the thorax protects the heart and lungs.
● It provides a base for the attachment of muscles and so allows
MOVEMENT with the bones acting as levers
● Bones are a source of BLOOD CELLS and a store for minerals
required for the body to function. For example, red and white blood
cells are produced in the bone marrow, which is found in the middle
of bones.
Main types of bones
● LONG BONES are longer than they are wide, they function as levers.
● SHORT BONES have a short axis and are found in small spaces
such as the wrist. They serve to transfer forces
● FLAT BONES have a broad surface and serve as places for
attachment for muscles and to protect vital organs
● IRREGULAR BONES do not fall into any category due to their
non-uniform shape. Primarily consist of cancellous bone, with a thin
outer layer of compact bone
● SESAMOID BONES usually short and irregular bones, imbedded in a
tendon where it passes over a joint which serves to protect the
tendon
Anatomical Position - a reference to position where the subject is standing
erect, facing front on and with palms forward
● Superior - towards the head;
● Inferior - towards the feet
● Anterior - towards the front
● Posterior - towards the back
● Medial towards the midline of the body
, ● Lateral - towards the side of the body
● Proximal - towards the body’s mass
● Distal - away from the body’s mass
TYPES OF JOINTS
Joints are where one or more bones meet. Some are fixed like a rib-cage,
or they can move like an elbow. Joints are classified accoreding to their
degree or movement. Joints may be classified as
● Fibrous or Immovable
● Cartilagnious or slightly moveable
● Synovial or freely moveable
FIBROUS joints occur where bone ends are joined by strong, short bands
or fibrous tissue such as in the skull. This type of joint DOES NOT ALLOW
ANY MOVEMENT TO OCCUR
CARTILAGNIOUS joints is where the bones are seperated by a disc or
plate made up of tough fibrous cartilage. For example the joints of the
vertebrae or spine are seoerated by this tissue thus causing limited
movement
SYNOVIAL joints allow for a RANGE OF MOVEMENT. These include hinge
joinnts (knee and elbow) and ball and socket joints (hip & shoulders).
Synovial joints are made possible with the use of tendons, ligaments,
cartilage, and synovial fluid.
What Connects These Joints?
● LIGAMENTS are fibrous bands that connect bones to bones. These
maintain stability in the joint.
● TENDONS are though inelastic cords that attach muscles to bones.
These further strengthened the joint and allow the joint to move
● CARTILAGE is a smooth shiny surface in the bones which allow them
to glide across each other freely
, ● SYNOVIAL FLUID is a lubricant that keeps the joints moist and
nourishes the cartilage to enable easy movement
● HYALINE CARTILAGE while synovial fluid acts as a cushion between
articulating surfaces of the bones, they are also covered with a layer
of smooth, shiny cartilage that allows bones to move freely over each
other. Thicker in the leg joints, where there is greater weight bearing.
MUSCLE RELATIONSHIPS
● AGONIST - an agonist or prime mover is the muscle causing the
major action. there are agonists for all moveable joints and usually
more than one is involved in a particular joint movement.
● ANTAGONIST - An antagonist is a muscle tat must relax and
lengthen to allow the agonist to contract, thus helping to control an
action. The agonist works as a pair with the antagosist muscle. The
two roles are interchangeable depending on the direction of
movement.
● STABILISER - Stabiliser or fixator muscles act at a joint to stabilise it,
giving the muscles a fixed base. the muscle shortens very little during
its contraction, causing minimal movement. This permits the action to
ne carried out correctlu and allows other joints to work more
effectivley. For example in a dynamic movement such as throwing,
while some shoulder muscles serve to propel the object, others act as
stabilisers to allow the efficient working of the elbow joint and to
reduce the possibility of damage to the joints
TYPES OF MUSCLE CONTRACTIONS
When a muscle is stimulated, it contracts. This may happen in a number of
ways. There are three principal types of muscle contraction - concentric,
eccentric and isometric,.
A CONCENTRIC contraction is the most common type of muscular
contraction. During this contraction, the muscle shortens, causing
movement at the joint. Examples of concentric contractions are the
, contraction of the rectus abdominis to raise the trunk during a sit-up, or the
biceps contracting to lift a weight.
An ECCENTRIC contraction occurs when the muscle lengthens while
under tension. The action often happens with the assistance of gravity.
Examples of eccentric contractions are the rectus abdominis extending to
gradually lower the trunk during the downward action of a sit-up, or the
biceps muscle fibres lengthening as the weight is returned to its original
position.
An ISOMETRIC contraction occurs when the muscle fibres are activated
and develop force, but the muscle length does not change; that is, the
movement does not occur. Isometric contractions are commonly seen in
attempted movements where a resistance cannot be overcome. Examples
are a weight-lifter trying to lift a weight that cannot be moved, or a person
pushing against a wall. In each case, the effort is being made, but the
muscle length does not change because the resistance is too great.
RESPIRATORY SYSTEM
Respiration is the process by which the body takes oxygen in and removes
carbon dioxide.
Every cell in our body needs a constant supply of oxygen and food to
maintain life and keep the body operating effectively.
Respiration is a process that occurs in practically all living cells. It uses
oxygen as a vital ingredient to free energy from food and can be
characterised by the following equation
This process is made possible through the respiratory system that
facilitates the exchange of gases between the air we breathe and our
blood. The respiratory system acts to bring about this essential exchange
of gases through breathing; the movement of air in and out of the lungs.
1) Oxygen enters the body through the mouth or nose. Through the nasal
cavities the air is warmed, moistened and filtered for any foreign material
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