Chapter 4: Acute Responses & o2 Uptake, Deficit & debt VCE Physical Education - Unit 3

Oxygen Uptake, Oxygen Deficit and Oxygen Debit Acute Responses Oxygen Uptake, Oxygen Deficit and Oxygen Debit

VCE Physical Education - Unit 3 Compare: VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Acute Responses When exercise commences, many changes occur within the body to meet the new demands been placed on it. These demands are largely derived by the need to supply the working skeletal muscles with energy. The magnitude of the changes (acute responses) will depend on a number of factors, however amongst the most important are the intensity and duration of exercise. KEY POINT: Acute responses occur to supply extra oxygen and nutrients to support ATP production. VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Acute Responses Acute responses to exercise. Increase in; Oxygen intake Transport of oxygen Extraction of oxygen from the blood Consumption of oxygen by working muscles Continues until maximum uptake is met (VO2 max) http://www.bbc.co.uk/science/humanbody/body/ VCE Physical Education - Unit 3

Body Systems - Respiratory VCE Physical Education - Unit 3

Respiratory Acute responses The respiratory system - exchange of gases (oxygen and carbon dioxide) occurs here (at the alveolar-capillary membrane) as the blood becomes oxygenated before returning to the heart and being circulated towards the muscles. VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Respiratory changes:  increased ventilation (provided by an increased tidal volume and increased respiratory rate) Increased diffusion of oxygen and carbon dioxide at the alveolar-capillary interface due to increased surface area and increased concentration gradients of oxygen and carbon dioxide VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Respiratory readings Read through pages 99-101 Be prepared to answer the “Thinking things through” questions verbally on page 101 VCE Physical Education - Unit 3

Body Systems - Circulatory VCE Physical Education - Unit 3

Circulatory Acute responses The cardiovascular system - the system that circulates blood around the body. Vascular = blood vessels, cardio = heart (cardiac muscle). Logically, it has three components - the heart (myocardium), the blood vessels, and the blood. The blood supplies the muscles with nutrients such as oxygen and glucose, it also helps remove wastes. VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 There are three types of blood vessels – arteries (which circulate blood towards the muscles), veins (which circulate blood back towards the heart, but because they do not have a high blood pressure and smooth muscles surrounding them, rely on muscles to propel blood back to the heart - venous return), and capillaries - the smallest blood vessels forming the link from arterioles (smaller versions of arteries) to muscle and muscle to venules (smaller version of veins) VCE Physical Education - Unit 3

Cardiovascular changes: Increased cardiac output (facilitated by an increased heart rate and increased stroke volume) increased systolic blood pressure redistribution of blood flow to active muscles, and as body temperature rises, to the skin increased a–vO2 difference - the difference in oxygen concentration between the arterioles and venules - a direct measure of how much oxygen the muscles are utilising VCE Physical Education - Unit 3

Cardiovascular Readings Read through pages 101 - 107 Be prepared to answer the “Thinking things through” questions verbally on page 107 VCE Physical Education - Unit 3

Body Systems - Muscular VCE Physical Education - Unit 3

Muscular Acute responses The muscular system - helps produce movement by pulling on bones. Changes here are: increased motor unit recruitment (a motor unit is a nerve cell and the muscle fibres/cells it excites, or stimulates) increased fuel metabolism increased oxygen consumption  increased production of metabolic by-products  increased muscle temperature VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Muscular Readings Read through pages 107-110 Be prepared to answer the “Thinking things through” questions verbally on page 110 VCE Physical Education - Unit 3

Oxygen Uptake, Oxygen Deficit and Oxygen Debit

Delivery of Oxygen to the Working Muscles The respiratory system is responsible for the extraction of oxygen from the atmosphere. This process is called ventilation. Diffusion – Exchange of gases based on concentration levels (High to low). Occurs at a cellular level (In the lungs and in the muscle cell) Cardiac output (Heart rate x stroke volume) - The heart pumps out oxygenated blood to the vascular system. Oxygen combines with haemoglobin in the blood Myoglobin, in the muscle attracts the oxygen from the blood and draws it into the mitochondria. Waste produces of aerobic metabolism is removed from the muscle cell via diffusion. See fig 5.2 p.119 VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Oxygen Uptake Limiting factors to oxygen uptake; Respiratory system – ability to take in oxygen Cardiovascular system – ability to transport and deliver oxygen Muscular system – Utilisation of oxygen Type of exercise performed, genetic inheritance, lifestyle, age and gender. VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Limitations to VO2 Max VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Oxygen Uptake - Sports VCE Physical Education - Unit 3

Heart Rate and Oxygen consumption When exercising; Our heart rate increases to meet the oxygen demands for the working muscles. The relationship between HR and oxygen consumption is linear. YOU MUST KNOW THIS RELATIONSHIP Trained athletes are able to utilise their oxygen uptake more efficiently than non trained people. See fig 5.3 p.119 VCE Physical Education - Unit 3

Heart Rate and Intensity VCE Physical Education - Unit 3

Oxygen Uptake, Oxygen Deficit and Oxygen Debit

VCE Physical Education - Unit 3 Oxygen Deficit Oxygen deficit occurs when the demand for oxygen exceeds the supply of oxygen available. The body therefore needs to obtain ATP through anaerobic pathways. Short duration/high intensity – Lactic acid is produced but is removed once oxygen demands are met. Performance is hindered due to the presence of lactic acid Once oxygen demands are met, the body reaches its steady state. Aerobic glycolysis assists in the removal of lactic acid. VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 Oxygen Consumption VCE Physical Education - Unit 3

Oxygen Uptake, Oxygen Deficit and Oxygen Debit Oxygen Debt Oxygen Uptake, Oxygen Deficit and Oxygen Debit

VCE Physical Education - Unit 3 Oxygen Debt After exercise our demand for ATP decreases but we still need to ‘repay’ the oxygen needed during exercise. This is why we puff after intense activities. The higher the intensity and duration of activities, the longer the oxygen debit. VCE Physical Education - Unit 3

EPOC Another term used for oxygen recovery is EPOC – excess post-exercise oxygen consumption. Alactacid Debt – Oxygen used to restore ATP and PC stores Lactacid Debt - Oxygen used to remove lactic acid from cells/blood. Additional oxygen is used to recover the energy systems. EPOC Fast Replenishment (0  3 minutes) Slow Replenishment (0 minutes  hours) ATP resynthesis Return core temperature to pre-exercise levels PC resynthesis LA converted to CO2 & H2O Absorption of H+ ions (buffering) Restore oxygen to myoglobin LA converted to glycogen, protein & glucose Restoring heart rate, ventilation & other body systems to pre-exercise levels VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 VCAA Questions VCE Physical Education - Unit 3

VCE Physical Education - Unit 3 VCAA Questions VCE Physical Education - Unit 3