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Short term effects of exercise (Cardiovascular System Responses (Heart…
Short term effects of exercise
Skeletal System
Osteoclast Activity
Break down the tissue to allow new growth
Weight baring exercise stimulates the activity of osteoblasts and supresses osteoclast activity, maintaining a healthy bone density.
Synovial Fluid
Thick, straw-coloured liquid that acts as a lubricant and is found primarily in the cavities of synovial joints.
Exercise increases the amount of synovial fluid.
Muscular System Responses
Muscle Fibre recruitment
First, slow twitch (type 1) muscle fibres are brought into action, then fast-twitch muscle fibres (type11a and type 11x).
High intensity = type 11x
Medium intensity = type 11a
Low intensity = type 1
Blood Flow to Woking Muscles
Vascular Shunting
shunt blood and sweat
increases blood flow to muscle
decreases blood flow to digestive system
Micro-tears
Muscle fibres will contract and relax against each other, resulting in microscopic tears to the fibres.
When you rest after the activity your body heals and uses proteins to fill the gaps in the tears.
Temprature
During exercise all muscles require energy, gained from fuels such as carbohydrates and fats
One of the products is heat. As the muscles warm up, blood circulating through the muscles is also warmed resulting in a rise in the body's temperature.
The amount of heat your muscles produce is related to the amount of work they perform: the more exercise, the more heat they produce.
Cardiovascular System Responses
Cardiac Cycle
Speeds up to meet the demands of the exercise
Factors that changes as a result:
heart rate increases
amount of blood increases
blood pressure increases
waste products are removed
blood is diverted
vasoconstriction
vasodilation
Anticipatory increase in heart rate
Occurs before the start of exercise
Heart rate can be changed by neurotransmitters such as adrenaline and noradrenaline, released from the brain.
Before exercise, the heart rate increases and the subsequent increase in blood flow has already begun to supply oxygen and nutrients to the working muscles
Cardiac output
The volume of blood pumped out of the heart in 1 minute
expressed as Q
Is equal to heart rate multiplied by the stroke volume
Changes in blood pH
The pH of blood is generally between 7.2 and 7.5
During exercise - we go towards being more acidic due to waste products such as carbon dioxide and lactic acid
blood pH
Heart rate
Changes according to the body's needs
Increases during exercise to deliver extra oxygen to tissues and remove carbon dioxide
The sympathetic nerve speeds up the heart
The vagus nerve (parasympathetic nerve) slows down the heart
Stroke volume during maximal exercise does not increase - left volume is already full to capacity
Stroke volume
The amount of blood pumped by the left ventricle in one contraction.
Increases during exercise
Goes from 70-80ml per beat to around 110ml
Arteriovenous oxygen difference (a-v02 diff)
Arterial blood
bright red in the colour due to high concentrations of oxygen
when the blood leaves the heart
Venous blood
Darker red due to high concentrations of carbon dioxide
delivered O2 to the muscle
At rest - smaller gap
During exercise - bigger difference
Blood pressure
Determined by two factors:
cardiac output
the resistance offered by blood vessels
Higher exercise intensity = greater rise in heart rate
Respiratory
Control of breathing rate
chemical - chemoreceptors
neural control - respiratory receptors
Respiratory muscles
Diaphragm
intercostal muscle
Additional muscles that aid breathing
Sternocleidomastoid
External Obliques
Internal Obliques
Rectus Abdominus
Transverse Abdominus
Tidal volume
The amount of air ventilated in or out of the lungs in one breath
Trained athletes achieve the required alveolar ventilation by increasing tidal volume and only minimally increasing breathing rate.
Minute volume
At a low to moderate exercise intensity, tidal volume and breathing rate increase proportionally
At a high exercise intensity, tidal volume reaches a peak so any further increase in minute volume requires an increase in breathing rate
Oxygen Dissociation Curve
Partial Pressure
pressure applied by a single gas in a mixture of gasses
Shows the relationship between the percentage of oxygen saturation of blood and the partial pressure of oxygen
Increased temperature and lower blood pH concentration affect the oxygen dissociation curve
In the lungs, the partial pressure of oxygen is high therefore haemoglobin has a high affinity
Neuromuscular System
Motor Neurons
Carry information from our central nervous system to out muscles
Sensory Neurons
Carry information from our skin to our central nervous system
Muscle spindles and Golgi tendon organs provide sensory information about the intensity of exercise, allowing smooth, coordinated movement patterns
Detect changes in the environment
Thermoreceptor
Detects change in temperature
Baroreceptors
Detects change in blood pressure
Chemoreceptors
Carbon dioxide
Hydrogen
Lactic acid
endocrine System Responses to Short Term Exercise
Oestrogen
Female sex hormone which controls puberty and strengthens bones
Exercise can lower levels of circulating oestrogens
Increases seretonin
Modifies the production and the effects of endorphins
Cortisol
Stress hormone
Helps control blood pressure and metabolism
Increases blood sugar levels
Testosterone
Involved in the development of muscle tissue and muscular strength
Increases the number of neurotransmitters
Encourages muscle growth
Increases levels of human growth hormone (HGH)
Human Growth Hormone
Stimulates general body growth and the lengthening of bones in particular
Noradrenaline
Acts as a neurotransmitter
Low levels are associated with depression
Acts to increase force of skeletal muscle contraction and the rate and force of contraction
Adrenaline
Anticipatory rise
Vasoconstriction and vasodilation
Increases heart rate, breathing rate and metabolic rate and improves the force of muscle actions
Energy Systems
During exercise, the body does not switch from one energy system to another - energy is derived from all systems at all times. However, the emphasis of which is used is dependant on intensity
ATP - CP
high intensity
PC is broken down, releasing both energy and a molecule (which is then used to rebuild ATP). The enzyme that controls the breakdown of PC is called creatine kinase.
The ATP-PC system can operate with or without oxygen, but because it does not rely on the presence of oxygen it is anaerobic.
The ATP-PC system can sustain all-out exercise for 3-15 seconds.
ATP Production
ATP if formed when adenosine diphosphate (ADP) binds with a phosphate
Energy is stored in the bond between the second and third phosphate groups
When a cell needs energy it breaks off the phosphate for adenosine diphosphate (ADP)
Lactate system
Medium intensity (just after ATP-PC)
Glycolysis = the breakdown of glucose
It consists of a series of enxymatic reactions. The end product of glycolysis is pyruvic acid which is used in a process called the Krebs cycle or converted into lactic acid.
Krebs Cycle
Anaerobic glycolysis occurs at times when energy is required in the absence of oxygen
It involves the breakdown of glycogen to form ATP plus lactate
The build up of lactate in the muscles stops the use of this energy after 40 to 60 seconds
Pyruvic acid and hydrogen is formed. A build up of hydrogen turns the muscle acidic so NAD molecules remove hydrogen
NAD is reduced to NADH which gets rid of the hydrogen during the electron transport chain to be mixed with oxygen to form water
If there is insufficient oxygen, NADH cannot release the hydrogen and they build up in the cell.
Aerobic