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Before the start of exercise your heart rate usually increases above resting levels. This is known as anticipatory heart-rate response. This is because the nerves that directly supply the heart and chemicals in the blood can rapidly alter the heart rate. It is also worth noting that heart rates start to rise prior to any type of exercise – just the thought of exercise is enough to trigger a heart rate response. This initial response serves simply to prepare the body for activity and is controlled by the sympathetic division of the autonomic (involuntary) nervous system. Stroke volumes also rise as a person starts to exercise and continue to rise as the intensity of the activity increases

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The Anticipatory Response is when the heart rate increases at the beginning of exercise. The heart rate can be changed by chemicals by neurotransmitters, called adrenaline and nor-adrenaline which are released and found in the brain. These neurotransmitters are the chemicals found and released from the brain which allow an impulse from one nerve cell to pass to another nerve cell. These chemicals tell the heart to get ready for exercise therefore there is an increase in beats per minute, heart rate increases. By increasing our heart rate our body begins to supply oxygen and nutrients for our working muscles.

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During exercise, the skeletal muscles are working harder and require an increase in the oxygenated blood. Your body adapts by sending more blood volume to those working muscles, and it does so by pulling blood flow away from the less active organs at that time. The less active organs are the liver, kidneys and intestinal tract. This is why it is recommended not to eat a large meal prior to exercise, since digestion will generate a competition for blood flow between the skeletal muscles and the gastrointestinal tract.

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Cardiovascular responses - increased blood pressure

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Cardiovascular responses - increased blood pressure

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To accommodate for the increased need for blood and oxygen during exercise, the vessels of the cardiovascular system dilate, which is called vasodilation. Some of your capillaries, the smallest vessels, are also "activated." This activation of the capillaries and the vasodilation lasts several hours after exercise. Your blood pressure is the pressure of the blood on your arterial walls. During exercise, your systolic blood pressure should rise due to the increase in blood volume, while diastolic pressure should remain about the same. Because the vasodilation lasts for several hours after your workout is over, your blood pressure should be slightly lower than your resting value prior to exercise. This is why physicians often recommend physical activity as a means of controlling blood pressure.

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As muscles begin exercising, the arterioles serving the muscle dilate to provide more blood flow. By itself, this vasodilation would lower the total peripheral resistance and thus mean arterial pressure. However, arterial pressure does not decrease because other parts of the cardiovascular system are adjusted to support the increased blood flow to the muscles. Let's first look at the muscle arterioles and then at the various changes in the cardiovascular system that support the increased flow of blood to the exercising muscles.

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The aerobic system produces far more ATP than either of the other energy systems but it produces the ATP much more slowly, therefore it cannot fuel intense exercise that demands the fast production of ATP.  The advantages of the ATP-PC system is that you can perform high intensity exercises without relying on oxygen whilst doing them and with no by-products.

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The increased heart rate increases the rate of blood flow around the body. The increased rate and depth of breathing increases the rate of gaseous exchange in the lungs. The muscles store glucose as glycogen. This can then be converted back to glucose for use during exercise.

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Tidal volume is the amount of air held in the lungs. The amount of air breathed out in and out in each breath is approximately 500cm3, however only about 2/3 of the oxygen you breathe in reaches the alveoli where the gaseous exchange in the body occurs and the remainder of the oxygen is just breathed out. During exercise tidal volumes increases to allow more oxygen to reach muscles that need the oxygen and to have a supply of oxygen in the blood to be used. The intercostal muscles which help expansion of the thoracic cavity works harder to increase the expansion during inhalation to take in more air

If the intensity of the exercise continues to rise, the amount of oxygen you are able to take in will eventually reach its maximal point and the person will reach their vo2 max, this means that they have reached their maximal level for oxygen consumption.

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Responses to physical activity ( increased breathing rate)

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Responses to physical activity ( increased breathing rate)

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When exercise begins there is an almost immediate increase in breathing rate.
this comes as a  result of receptors working in both the muscles and joints detecting by-products and harmful substances. when exercising the body requires the production of ATP to be constant, to produce ATP oxygen and nutrients are needed to create this ATP, however as a result of producing ATP one of the by-products is carbon dioxide and the body needs to remove this as soon as possible. The brain then sends signals to the respiratory muscles and the lungs to tell them to increase the breathing rate to get rid of these substances rapidly. as well as breathing more rapidly to get rid of substances, we also need to breathe more rapidly to get a quicker supply of oxygen to meet the muscles demand more oxygen after changes in exercise intensify

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The human respiratory system is a series of organs responsible for taking in oxygen and expelling carbon dioxide. The primary organs of the respiratory system are lungs, which carry out this exchange of gases as we breathe.

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Energy systems - Adenosine Triphosphate (ATP)

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Energy systems - Adenosine Triphosphate (ATP)

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Our body stores energy in the form of ATP
ATP is made up of one adenosine molecule and 3 phosphate molecules.
Our body requires energy and the source for this energy comes from the breakdown of ATP in our cells. 3 types of nutrients we can get energy from: carbohydrates, fats and protein

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The lactic acid system is an anaerobic energy system in which the high energy compound adenosintriphosphate (ATP) is manufactured from the breakdown of glucose to pyruvic acid in the muscle cells. The end product of glycolysis under aerobic conditions is pyruvate, a salt or ester of pyruvic acid.

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The stress placed on your muscles during exercise leads to tiny tears in your muscle fibers, these tears will cause swelling in your muscle tissues, this creates pressure on the nerve ending and pain. To repair these tears protein is needed to build and repair these tears making them stronger. For example a footballer will also vulnerable to this as throughout a game a lot of stress is placed on their muscles

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Acute responses to the skeletal system are demonstrated by the changes within the joints. Within the joint synovial fluid is secreted, the synovial fluid helps to provide a larger range of movement during acute exercises. When the synovial fluid is secreted it becomes less viscous making it easier for a large range of movement to take place. having an increased range of movement would benefit a sprinter because it will make them quicker as they can move more freely

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Muscle pliability relates to the stretchiness of your muscles and connective tissues.
Warming up before exercising is a must, as it helps to reduce the risk of  injury. This is done as we warm we are producing heat, from our muscles contracting and creating friction. When our muscles are stretchier there is an increase in movement resulting in pliability within our muscles and tendons. For example a gymnast warming before a competition will allow there muscles to reach there maximum 'give'.

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As the blood supply increases, there is an increase in temperature and metabolic activity. As we begin to exercise our muscles need to work faster to produce energy at a faster rate, to keep up with the movement in the muscles. Oxygen in the red blood cells and other nutrients and minerals are stored in the muscles to supply these muscles with energy (glucose.) During exercise our muscles contract causing friction producing heat as much as 70% of body heat is produced by energy production in muscle tissue. Vasodilation of the capillaries at the skin, takes place to help regulate body temperature, allowing more blood to come to the skin therefore resulting in our bodies sweating.    If the temperature in our bodies is not maintained and gets too high , the enzymes in our bodies will begin to die. The greater the demand for oxygen is met by an increase in blood supply through capillary dilation.

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Some responses to the musculoskeletal system to physical activity are: increased blood supply, increased muscle pliability, increased range of movement and muscle fibre tears.
The function is to support and make the body (posture) it includes things such as tendons,ligaments, muscles, bones and cartilage.