This topic serves as an introduction to some of the biological principles involved in the study of human movement and physical performance. It is intended that pupils will acquire knowledge and understanding of a range of processes associated with movement and of the relationships between physical activity and healthy living.

Movement

The purpose of this sub-topic is to provide a background to the primary requirements of physical activity, i.e. support and movement. It is intended to provide some understanding of how movement is achieved, of the range of movement that is normally available and of the application of these to physical activities.

The skeleton:

• Provides a framework for support of the internal organs
• Provides a system of levers on which to attach muscles and bring about movement
• Protects vital body organs such as:

• Brain
• Heart
• Lungs

The Synovial Joints

Synovial joints are the joints which are able to move They allow the bones to move against each other The hinge joint: Found at the elbow, knee and fingers Permits movement in a single plane of movement (see textbook for planes of movement) The ball and socket joint Found at the shoulder and between the hip and thigh Permits movement in all three planes of movement. Joints are held together by elastic ligaments The structure of the synovial joint is shown. The cartilage is smooth to reduce friction The cartilage is spongy to absorb shocks The synovial fluid is produced by the synovial membrane and is oily to reduce friction in the join

Bone is made of:

• Living cells which contain:
  • the hard mineral Calcium phosphate
  • flexible fibres of collagen

• together these make a strong and durable material.

The Need for Energy

The purpose of this sub-topic is to give pupils the opportunity to investigate systems of the body that provide muscles with the energy resources that they require in producing movement. This involves investigation of the structure of the respiratory and circulatory systems and how these structures function in meeting the energy requirements of muscles.

Energy

• Our bodies gain energy through food
• Our bodies expend energy in:
  • Movement
  • Heat
  • Chemical processes
• Our bodied require to balance this energy:
  • If our energy intake is greater than our energy use:
    • Energy is stored as fat
    • There is a danger of obesity and its related diseases
  • If our energy intake is less than our energy output
    • Fat is converted to energy
    • We loose weight
    • There is a danger of starvation if the process continues for too long.

Breathing and the lungs

We obtain oxygen for respiration by breathing During breathing we take oxygen into our blood During breathing oxygen is released from the blood into the exhaled air. Structure:   The cartilage bands keep the windpipe open when our heads turn and move The trachea branches into two bronchi (s. bronchus), the bronchi branch into many bronchioles The diaphragm is a flat sheet of muscle and connective tissue that moves up and down to help breathing. The ribs also are involved in breathing (see below) as well as their protective role (see above). Each bronchiole ends in an air sac where gas exchange takes place (see below)

Breathing

• To breathe in:
  • The muscles of the diaphragm contract causing the diaphragm to move down
  • The intercostal muscles between the ribs contract causing the ribs to move up and out
  • The volume of the chest increases and the pressure in the lungs decreases
  • Air is drawn in.

• To breathe out:

• The muscles of the diaphragm relax causing the diaphragm to move up
• The intercostal muscles between the ribs relax causing the ribs to move down and in
• The volume of the chest decreases and the pressure in the lungs increases
• Air is forced out.

• Cleaning
• The tubes of the lungs (trachea, bronchi and bronchioles are lined with:
  • Cilia (tiny, beating hair like structures)
  • Mucus producing glands
  • Germs, dust and dirt are trapped in the sticky mucus
  • The cilia carry the germs, dust and dirt out of the lungs

Gas Exchange

Takes place at the air sacs These are microscopic sacs at the end of the bronchioles Here oxygen diffuses into the blood And carbon dioxide diffuses out of the blood Air sacs are well adapted as gas exchange surfaces for the following reasons: The membranes of the airs sac and the capillaries are thin (one cell thick) The surface area is very large due to the very large numbers of air sacs There is an excellent blood supply due to the many capillaries The surface is moist to allow the oxygen to dissolve

Circulatory system

The heart is a muscular pump which pumps blood around the body It is made up of four chambers: The left and right atria (s. atrium) The atrium pumps blood into the ventricle The left and right ventricles The ventricles pump blood to the organs and tissues of the body. Blood follows a predictable path through the heart: Blood enters the heart through the vena cava from the body tissues and organs It enters the right atrium which contracts to drive the blood into: The right ventricle, the ventricle contracts sending the blood into: The pulmonary artery, which carries the blood to the lungs. From the lungs the blood enters the pulmonary vein which carries it to: The left atrium which contracts to drive the blood into: The left ventricle, the ventricle contracts sending the blood into: The aorta, which distributes the blood to the body’s tissues and organs.

• Within the heart four valves control the direction of blood flow:
  • From the atria into the ventricles
  • From the ventricles into the aorta and pulmonary artery
  • They prevent the blood flowing backwards during the relaxation of the heart

• The walls of the left ventricle are much thicker than the walls of the right ventricle:
  • The right ventricle pumps blood a short distance through the lungs
  • The left ventricle pumps blood a long way through all the rest of the body’s tissues and organs
  • The left ventricle must therefore be stronger and is therefore thicker.

• The muscles of the heart obtain their blood supply from the coronary artery which is the first branch off the aorta just as it leaves the heart.

The blood and its vessels

Blood vessels: Blood travels away from the heart in arteries. Arteries have thick, muscular walls to contain the blood under pressure. Blood flows through capillaries (see below) where material is exchanged with the tissues. Blood travels towards the heart in veins: Veins have little muscle, and have valves to ensure that the blood flows the correct way through the vessel. The pulse indicates that blood is flowing in the artery under the point of contact.

Gas and solute exchange In the capillary network various chemicals are exchanged between the cells and the blood by diffusion. Oxygen and food enter the cells Carbon dioxide and waste leave the cells The capillary network has several features that make is well adapted for exchange  The walls of the capillaries are thin (one cell thick) for efficient diffusion The network of capillaries gives a large surface area for diffusion. The network of capillaries gives an excellent blood supply to the cells.

Coordination

The purpose of this sub-topic is to provide understanding of the components of coordination, which apply to physical activity.

Sight The structure of the eye: The cornea does most of the focusing of the light. The lens fine focuses the light onto the retina, the lens compensates for near and distance focusing. The iris controls the size of the pupil and thereby controls the intensity of the light entering the eye.  The iris compensates for bright and dark conditions. The retina is a layer of light sensitive cells that turn the light energy into electrical energy . The optic nerve carries the electrical signals to the sight areas of the brain.

Binocular vision

• We need two eyes to judge distance properly:
  • Each eye sends a slightly different image to the brain
  • The closer the object is the greater the difference
  • The brain works out the distance from processing these two images.

Hearing

The structure of the ear Sound is pressure waves in the air The pressure waves strike the eardrum and make it move, turning the sound energy into movement (kinetic) energy. The movement is transmitted to the cochlea by the middle ear bones (three small bones) In the cochlea the kinetic energy from the bones is turned into electrical energy The auditory nerve carries the electrical signal to the auditory parts of the brain. The semicircular canals are involved in balance Each of the three canals lies in one plane each along the x-axis, the y-axis and the z-axis. When the head accelerates fluid moves in the canals depending on the direction of movement Sensors pick up the moving fluid and the brain calculates the direction of movement.

Judging distance and direction

• We need two ears to judge the direction of sound properly.
  • Sound arrives slightly earlier at one ear than the other.
  • Each ear also receives a slightly different sound which is sent to the brain
  • The brain works out the direction from processing these two sounds.

The Nervous System

The nervous system is composed of:  The brain the spinal cord: Together the brain and spinal cord make up the central nervous system. The central nervous system sorts out information from the senses and sends messages to the muscles. Information in the environment that is sent to the brain is called a stimulus. The action that is carried out by the brain and muscles is called the response. the nerves: motor nerves, which carry signals from the brain to the muscles. sensory nerves, which carry signals from the senses to the brain. Structure of the brain: The cerebrum handles thought, imagination, personality and other higher functions The cerebellum deals with balance and coordination The medulla handles heartbeat, breathing and peristalsis the spinal cord carries nerve signals to and from the brain.

The reflex arc

Changing levels of performance

The purpose of this sub-topic is to allow pupils to measure some physiological changes resulting from physical activity, and to use these as indicators of level of performance and of fitness.

Fatigue

• When a muscle or group of muscles is exercised continuously or rapidly it gets fatigued.
  • When you exercise the muscle cells begin to respire faster to provide more energy.
    • They need more food and oxygen to do this.
    • The heart rate and breathing increase to provide the muscle cells with more food and oxygen.
  • There comes a point when heart, lungs and blood are not able to supply enough oxygen for the muscle cells’ aerobic respiration .
    • The muscle cells respire anaerobically.
    • When they respire this way they produce lactic acid.
    • Lactic acid build up in the muscles causes fatigue.
  •  Anaerobic respiration:
    • sugar lactic acid + Carbon dioxide.

Exercise

• During exercise in an athlete the heart rate and breathing increase less than in an untrained person.
  • Training improves the efficiency of the heart, lungs and circulation
  • Recovery time is the time taken after exercise stops for heart rate and breathing to return to normal. 
    • During this time the excess lactic acid is changed back to storage carbohydrate
    • Recovery time decreases as training improves the level of fitness
    • In the graph shown below, exercise begins at 2 minutes and stops at 7 minutes. 
    • Recovery time is from 7 minutes to 15 minutes.

    

• Three factors can indicate the level of fitness of a person
  • The rise in heart rate during exercise
  • The rise in breathing during exercise
  • The time taken for recovery time
  • These figures will be lower in fitter people.

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