The structure and functions of the skeleton

Muscular skeletal system : The name used to describe the muscular skeletal system and the muscular system working together.

There are 206 bones in the human body.

There are 4 different types of bones

• Long bones – to enable gross (large) movements

• Short bones – to enable finer controlled movements

• Flat bones – often large and protect vital organs

• Irregular bones - specifically shaped to protect

Articulating bones : Bones that meet at a joint to enable movement

• Shoulder : scapula, clavicle, humerus

• Elbow : humerus, radius, ulna

• Hip : pelvis, femur

• Knee : femur, patella, fibula, tibia

• Ankle : tibia, fibula, talus

Functions of the skeleton

The skeleton is rigid supporting the framework of bones inside the body, to which all the soft tissues and organs are attached.

Together the bones and muscles form a machine which can perform many different tasks.

There are 6 main functions of the skeleton

• Support – without support we would be unable to move and be a mass of soft tissue.

Eg: our vertebrae supports the head

• Protection – The hard nature of the bones means the skeleton can protect the more delicate parts of the body (vital organs). This reduces the chance of injury allowing players to continue to train and play sports.

Eg: our ribcage protects our lungs, cranium protects the soft tissue of the brain

• Movement - The skeleton is joined to allow us to move when the muscles attached to them contract and pull on the bone

Eg: The bones and joints work with muscles to enable us to walk, jog and sprint

• Shape and structure – Without the skeleton we would not be able to move. The skeleton provides something for the muscles to attach to

Eg: the bones in the legs support the body, the vertebrae supports the head

• Produce blood cells – Red and white bloods cells are made of bone marrow which is found at the ends of the femur and the humerus and also at the ribs ,sternum, pelvis and vertebrae. Red blood cells are important for aerobic activity as they help oxygen transportation around the body. White blood cells are fight off infections, and platelets help blood to clot following an injury

• Storage of minerals – Bones act as reservoirs for vital minerals such as calcium and phosphorus. These are essential for major body functions. Their role in physical activity is linked to the general health of the athlete, which affects sporting performance.

Joints

A joint is where two or more bones meet and muscles act together to cause movement

• The human skeleton is jointed to allow movement

• Muscular contraction causes the bones to move about the joints

Synovial joints are otherwise known as freely-movable joints

• These are the largest group of joints found in the body, eg: hips, shoulders, elbow, ankle and knees

Types of synovial joints -

• Ball and socket joints – These are the most moveable joints in the body. These can move away from the body, back towards the body and can also rotate.

Eg: Hips and shoulders

• Hinge joints – Hinge joints can only move towards or away from the body like a hinge on a door.

Eg: Knee, ankle, elbow

Movement at synovial joints – Different types of synovial joints allow different kinds of movement…

• Extension : Straightening or extending a limb

Eg: the arm can be extended at the elbow

• Flexion : Bending or flexing a limb

Eg: the leg can be flexed at the knee

• Abduction – Moving a limb away/towards from the centre line of the body.

Eg : the leg can be moved away from the centre of the body at the hip

• Adduction – Moving a limb towards the centre line of the body

Eg : the arm can be moved towards the centre line of the body at the shoulder.

• Rotation – A circular movement around a joint.

• Circumduction : Movement of a bone or a limb in a circular pattern a combination of flexion, extension, adduction and abduction

Eg : the shoulder when swimming butterfly

• Plantar Flexion : movement at the ankle joint that point the toes

Eg : in the ankle

• Dorsi-flexion : movement at the ankle that flexes the foot upwards

The structure and function of the muscular system

Tendons

A tendon is connective tissue that attaches muscle to bone

The role of a tendon is to transfer the effort created by a contracting muscle to the bone, resulting in movement of that bone

Muscles at the 5 main joints -

• Shoulder - Deltoid, Trapezius, Pectorals, Latissimus dorsi, Biceps, Triceps, Rotator cuff

• Elbow – Biceps, Triceps

• Hip - Gluteals, Hip flexors

• Knee – Quadriceps, Hamstrings

• Ankle – Gastrocnemius, Tibialis anterior

Antagonistic Pairs

Muscles can only PULL not push and are arranged in pairs on either side of joints

These pairings of muscles are known as antagonistic pairs

• The muscle that tenses is the agonist (prime mover)

• The muscle that eccentrically contracts is the antagonist

• Muscles pull by contracting, they cannot push to produce the opposite movement

These muscles make up obvious antagonistic pairs

• Biceps and triceps - (acting at the elbow to create flexion and extension)

• Hip flexors and gluteals - (acting at the hip to create flexion and extension)

• Hamstring group and quadriceps groups- (acting at the knee to create flexion and extension)

• Tibialis anterior and gastrocnemius (acting at the ankle to create dorsiflexion and plantar flexion)

Types of Muscular Contraction

• Isometric – Do not create movement, the muscle neither shortens nor lengthens it remains the same Eg : To support a weight in a stationary position/ To hold the body in a particular position eg handstand, plank, arabesque

• Isotonic – These create movement. The muscle length changes when it contracts, resulting in limb movement

• Concentric – When the muscle contracts and shortens

• Eccentric – When the muscle contracts and lengthens

The structure and function of the cardio-respiratory system

The respiratory system – This brings oxygen into the body so it can be used to produce energy and enable activity. it then gets rid of carbon dioxide a waste product which is produced in the muscles during exercise.

Key terms

Cardio-respiratory- The name used to describe the respiratory system and the cardiovascular system working together

Circulatory system – Heart, blood vessels, and blood

Respiratory System – Lungs and airways

Functions – Enable the body to breathe, pump blood and oxygen around the body

Gaseous exchange – The process where oxygen from the air in the alveoli moves into the blood in the capillaries, while carbon dioxide moves from the blood in the capillaries into the air in the alveoli.

Haemoglobin - The protein found in red blood cells that transports oxygen as oxyhaemoglobin and carbon dioxide around the body

Oxyhaemoglobin - A chemical formed when haemoglobin bonds to oxygen

Alveoli - Small air sacks in the lungs where gas exchange takes place. Very thin, one cell thick, provides a moist and extremely large surface area for gaseous exchange to occur. Numerous capillaries run across the alveoli, ensuring a large blood supply to the area

Capillaries - A network of microscopic blood vessels. They are only one cell thick.

Diffusion Pathway - The distance travelled during diffusion. The diffusion pathway is short in gaseous exchange

1. Oxygen that has been breathed in passes through the alveoli and into the red blood cells in the capillaries

2. In the capillaries the oxygen combines with haemoglobin to form oxyhaemoglobin and is then carried around the body

3. At the same time haemoglobin carries carbon dioxide from the body to the capillaries

4. The carbon dioxide in the capillaries passes through the alveoli and is breathed out

Mechanics of breathing

Inhalation

• The diaphragm contracts. It flattens and moves downwards

• The intercostal muscles contract, raising the ribs and pushing out the sternum, making the chest cavity larger

• The lungs increase in size and the air pressure inside the lungs is reduced

• The air pressure outside the body is now higher than inside the body. Air travels from areas of high concentration to areas of low concentration, so air is pulled into the lungs

Exhalation​

• The diaphragm relaxes. It moves back up into a dome shape.

• The intercostal muscles relax, lowering the ribs and dropping the sternum, making the chest cavity smaller.​

• The lungs reduce in size and the air pressure inside the lungs is increased.​

• The air pressure outside the body is now lower than the air pressure inside the body. Air travels from areas of high concentration to areas of low concentration, so air leaves the lungs.​

What happens to your breathing during exercise?

• The lungs expand and contract more as more air is inhaled to supply more oxygen to the working muscles and more air is exhaled to remove the increased amount of carbon dioxide produced by the working muscles. 

• More muscles are involved in breathing when you exercise. The sternocleidomastoid, paired muscles in the side of the neck, assist in raising the sternum when you inspire. The abdominals pull the rib cage down more quickly, forcing air out quickly, when you expire.

Spirometer Trace

• A spirometer is a piece of equipment that measures the air capacity of the lungs

• It is a way of recording and drawing these volumes. The pattern of the trace will change as the amount of air you inspire and expire changes as a result of exercise.

• A spirometer measures the 5 following volumes associated with the lungs

Tidal volume – The normal amount of air inhaled or exhaled per breath

Expiratory reserve volume – The amount of air that can be forced out after tidal volume (after normal expiration)

Inspiratory reserve volume – The amount of air that can be forced in after tidal volume (a normal inspiration)

Residual volume - The amount of air that remains in the lungs after maximal expiration

Structure of the heart

KEY TERMS

Pulse – the rhythmic throbbing that you can feel as your arteries pump blood around the body. You can measure your heart rate using your pulse.

Backflow - the flowing backwards of blood for. Valves in the veins prevent back flow.

Diastole – the phase of the heartbeat when the chambers of the heart relax and filled with blood.

Systole – the phase of the heart between the chambers of the heart contract and empty of blood; when blood is ejected from the heart.

Cardiac cycle – one cycle of diastole and systole is called the cardiac cycle.

Blood pressure – the pressure that blood is under. The systolic reading measures the pressure the blood is under when the heart contracts. The dear stolice reading measures the pressure the blood is under when the heart relaxes

Blood Vessels

• Arteries

• Thick muscular walls with a small internal diameter - carry oxygenated blood away from the heart under high pressure

• Arteries do not have valves

• Your pulse is located in your arteries as they pulse as blood is carried through them

• Can vasodilate and vasoconstrict

• Veins

• Thinner walls with a larger internal diameter - blood pressure is low in the veins

• Veins carry deoxygenated blood back to the heart

• Veins contain valves that open due to the pressure of the blood flow and close to make sure that the blood does not flow backwards so there is no back-flow

• Capillaries –

• Microscopic blood vessels that link the arteries to the veins

• walls are very thin just one cell thick - tell out oxygen and carbon dioxide to pass through them during gaseous exchange

• deoxygenated blood becomes oxygenated at the capillaries

Pathway of blood

• Deoxygenated blood enters the right atrium from the superior vena cava and inferior vena cava​

• It then passes into the right atrium, through a valve and into the right ventricle.​

• The pulmonary artery transports deoxygenated blood to the lungs.​

• Gaseous exchange occurs, resulting in oxygenated blood.​

• The pulmonary vein transports oxygenated blood from the lungs to the left atrium. ​

• It then passes through a valve to the left ventricle.​

• Oxygenated blood is ejected from the heart and is transported to the body via the aorta.​

Cardiovascular system

The cardiovascular system carries blood around the blood.

How is blood redistributed during exercise?

During exercise the body alters its priorities. When the body is resting most of the blood is directed towards the organs, but during exercise most of the blood is directed towards the voluntary muscles. This ensures that voluntary muscles are able to work aerobically, which is the most efficient. Redistributing blood when exercise begins is achieved by vasodilation and vasoconstriction, which changes the internal diameter of the arteries that supply the body with blood. Vasoconstriction is the narrowing of the internal diameter of a blood vessel to restrict the volume of the blood travelling through it. This is so less blood is delivered to inactive areas. Vasodilation is when the internal diameter of a blood vessel widens to increase the volume of blood travelling through it. The arteries dilate more during exercise so more blood is delivered to active areas therefore increasing their oxygen supply

Cardiac Cycle

Blood pressure

• Two readings are taken when blood pressure is measured.​

• The pressure that the blood is under when contracting and ejecting the blood from the heart – SYSTOLIC PRESSURE.​

• The pressure that the blood is under when the heart relaxes (and fills with blood) – DIASTOLIC PRESSURE.

Redistribution of blood during exercise

Heart Rate

• The number of times the heart beats in one minute

• Units = beats per minute (bpm)

• Resting heart rate = 60-80 bpm

• Maximum heart rate = 220 – your age =

Stroke volume

• The amount of blood pumped out of the left ventricle each beat

• Unit = Milliliters (ml)

Cardiac output

Aerobic and anaerobic exercise

Aerobic exercise – Working at a low to moderate intensity so then the body has time to use oxygen for energy production and can work for a long amount of time

• Aerobic exercise takes place in the presence of oxygen

• When exercise is over a long period of time, not too fast and steady, the heart can supply all the oxygen the working muscles need

• When working aerobically the energy comes from carbohydrates

• These carbs are converted into glucose and oxygen

Intensity – The amount of energy needed to complete an activity. Working at a high intensity requires a large amount of energy. Working at a low intensity requires less energy

• Sporting examples include – long distance running, endurance cycling, long distance swimming

Anaerobic exercise - Working for short periods of time at a high intensity without oxygen for energy production

• Takes place in the absence of enough oxygen

• The heart and lungs cant supply enough blood and therefore oxygen to the working muscles

• Glucose is converted to energy without the presence of oxygen

• Sporting examples include – short distance sprinting (100m,200m), short distance swimming (25m,30m)

Excess Post-exercise Oxygen Consumption (EPOC) – The amount of oxygen needed to recover after exercise. It is characterised by an increased breathing after exercise

The recovery process

Cool down

• Gradually reduces the intensity of the exercise

• Helps maintain an elevated breathing rate/ heart rate

• Ensures blood continues to flow quickly to the muscles

• Replenishes working muscles with oxygen

• Helps the body convert lactic acid produced anaerobic exercise into glucose, carbon dioxide and water so your not stiff

Manipulation of diet

Drink water

• Drink water to rehydrate to replace fluids lost during exercise (sweat)

• How much water you need to drink depends on the intensity levels and duration of the exercise that was done

• Air temperature, humidity, and altitude effect how much water you need

Carbohydrate loading

• Carbohydrate loading increases the amount of carbs eaten which maximises the amount of glucose in the body

• More carbs = more glucose (body can meet better demands of the performance)

• Limits the length and severity of the recovery period

• Boosts performance

Timing of protein intake

• Important for power athletes to increase strength and speed

• Consuming protein after training

• Provides the body with nutrients it needs to heal tears quickly and build muscle

• Protein helps repair small tears that occur (hypertrophy)

Ice baths or massages

• Immediately after exercise

• Helps prevent DOMS (Delayed Onset Muscle Soreness)

• The muscle soreness you feel a day after intense exercise

The effects of exercise

Immediate effects

• Heart rate increases – as your heart works harder to deliver oxygen to the working muscles

• Breathe more deeply and frequently – as your body delivers more oxygen to working muscles

• Feel hotter – body temperature increases

• Sweat and skin will redden – this occurs as part of the body’s temperature control system

Short term effects (24-36 hours)

• Feel nauseous

• Feeling light headed

• Muscle ache/cramps

• DOMS (if exercise was intense)

• Feel tired/ fatigued

Fatigue – Physical fatigue is a feeling of extreme or severe tiredness due to a build-up of lactic acid in the muscles or working for a long period of time

The long term effects of exercise (occurs after months or years)

• Stamina will improve – this us your ability to exercise

• Muscles will increase in size and produce greater strength – when a muscle is strained, small tears are created. As they heal, they become thicker. This is called hypertrophy

• Heart will increase in size. This is called cardiac hypertrophy and your cardiac output increases. Your heart is able to deliver more blood and more oxygen to your working muscles, removing more carbon dioxide and other waste products like lactic acid

• Resting heart rate is lower (Bradycardia) – This is if you have a resting heart rate under 60 bpm

• Your body will change shape (for the better) – Exercise helps keep body weight down

• Improvements in specific components of fitness – increase in strength, muscular endurance, cardiovascular endurance, improvement in speed and flexibility

Hypertrophy – the enlargement of an organ or tissue caused by an increase in the size of its cells . When a muscle is trained, small tears are created. As they heal, they become thicker and increase in size