Body in Action

revision

Sub-topic (a) MovementState the functions of the skeleton.To protect vital organs. For example the ribcage

protects the heart and lungs.To provide support.To provide a framework for muscle attachment.Describe the range of movement allowed by the

hinge and ball and socket joints.A hinge joint (knee) can only move in one plane.A ball and socket joint (hip) can move in three

planes.

State the functions of ligaments and cartilage.The ligament attaches bone to bone across a

joint.The cartilage acts as a shock absorber (soft

cushioning) at the end of a bone at a joint.Describe the composition of bone.Bone is composed of living cells which make

up flexible fibres and hard minerals such as calcium phosphate.

Describe how muscles are attached to bones.Muscles are attached to bone by inelastic

tissues called tendons.

Describe how muscles bring about movement.

To bend an arm, for example, the bicep would contract while at the same time the tricep would relax bending the arm. To straighten the arm the bicep would relax while at the same time the tricep would contract.

Air sac

Blood capillaries

Describe the features that make capillary networks efficient at gas exchange.

Capillaries are very narrow tubes which branch repeatedly, forming such a dense network that that every living body cell is close to a capillary.

The combined surface area of the capillary network is enormous and the capillary walls are only one cell thick.

These properties of the capillary network will allow efficient gas exchange to occur between the bloodstream and the body cells.

Describe the function of the components of the blood.

PlasmaContains dissolved substances (amino acids,

glucose etc.) and blood cells.Red Blood CellsCarry oxygen around the body.White Blood CellsFight infection.PlateletsClot blood to stop bleeding at a wound.

Describe the exchange of gases between body cells and capillaries.

As oxygenated blood flows through a capillary close to a body cell, oxygen diffuses out of the capillary into the surrounding cells.

During respiration the cells produce carbon dioxide. The carbon dioxide diffuses out of the cells and into the capillary.

Carbon dioxide is then transported to the lungs in the blood.

Sub-topic (c) CoordinationState the benefit of having two eyes and two

ears.Two eyes allow accurate judgement of distances.Two ears allow accurate judgement of the

direction of sound. Identify the parts of the eye and state their

function.CorneaAllows light to enter the eye. IrisColoured part containing muscle. Controls

amount of light entering the eye.

Lens

Optic nerve

Pupil

Cornea

Iris

Sub-topic (c) CoordinationDescribe how the structure of semi-circular

canals is related to their function.The three liquid filled canals are situated at

right angles to one another. Each contains an ampulla containing a receptor

which is stimulated by movements of the liquid in the canal.

These are caused by the canal being rotated in its respective plane by movements of the head.

Messages are carried by a branch of the auditory nerve to a region of the brain that controls muscular activity for balance.

Nerves throughout the body

Sensory nerveRelay nerve

Motor nerve

Cerebrum

Cerebellum

Medulla

Sub-topic (d) Changing levels of performanceExplain muscle fatigue in terms of anaerobic

respiration.Under normal circumstances the energy

needed for contraction of muscles comes from aerobic respiration (glucose and oxygen).

During vigorous exercise the supply of oxygen cannot meet the demand.

Muscles will continue to use glucose anaerobically producing lactic acid and a little energy.

Oxygen debt is required to remove the lactic acid so that muscles can work properly.

Explain the relationship between the effects of training and recovery time.

Recovery time is the time it takes for the heart rate, breathing rate and the lactic acid levels to return to normal resting values.

A person who is in training will notice that the factors above will return to normal resting values quicker than a person who is not in training.

It can therefore be used as an indicator of fitness.

State the effects of training on the lungs and circulation.

Training involves vigorous exercise over a period of several weeks.

The lungs of an athlete are more efficient able to take in larger volumes of oxygen in each breath.

During training the heart muscle tissue gradually increases in strength and efficiency.

As a result the same volume of blood can be supplied to the muscles using fewer heartbeats.

Therefore the athlete’s circulation is more efficient.