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Investigate the initial responses of the cardiovascular and

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Lashaun greenaway

on 10 March 2014

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Transcript of Investigate the initial responses of the cardiovascular and

Unit 2:Sport and Exercise Physiology Assignment 1
Investigate the initial responses of the body to exercise

An increase of carbon dioxide when exercise has started and lactic acid builds up in the body and is detected by the chemo receptors. Due to this, signals are then sent back to the SNS, where more adrenaline is released in order to increase the Working heart rate
Blood Pressure
There are two types of blood pressure: systolic and diastolic.
Systolic blood pressure is the maximum pressure exerted from the heart, where as Diastolic blood pressure is the minimum pressure exerted from the heart
Cardiac Output
Cardiac output is the amount of blood pumped aound the body per minute. When exercising the cardiac output is increased because the heart rate and stroke volume is increased. During exercise the cardiac output will increase up to the point of exhaustion.
When you exercise in between 40-60% the stroke volume increases so the cardiac output increases.

Investigate the initial responses of the cardiovascular and respiratory systems to exercise
Before starting exercise the resting heart rate increases above the normal heart rate due to the release of adrenaline from the sympathetic nervous system (SNS)
The Heart Rates Initial Response To Exercise
Definition:The amount of blood pumped from the ventricles in one beat.
Once exercise has suddenly started, then the stroke volume will increase due to more blood being pumped around the body. Stroke volume usually increases very quickly at the start of exercise and then evens out gradually throughout the process of exercising
As the image shows the blue side is the Diastole side of the heart and the pink side being the Systole side.
Heart rate x Stroke Volume = Cardiac Output
HR x SV = CO
Diastolic blood pressure is the bottom number which indicates the pressure in the arteries when the heart is resting between beats.
The systolic blood pressure is the pressure exerted on the arteries when your heart beats.
As soon as exercise begins the systolic blood pressure increases in direct proportion to increase in exercise intensity. The central nervous system responds by constricting (this is called Vasoconstriction which is narrowing of the blood vessel lumen) blood vessels and increase the systolic blood pressure.
The diastolic blood pressure however doesnt change significantly or it may decrease.
The mean Arterial Pressure (MAP) wouldnt change however. The MAP is the product of both the SBP and DBP. The valsava maneuver can also increasde blood pressure due to forcing exhalation. This topic will be expanded on later.
Cardiovascular Information from:
Cardiovascular Responses to Acute Exercise (powerpoint)
Respiratory initial responses to exercise
Increased Breathing Rate

Valsava manoevre
Intercostal muscles
Increase in tidal volume
Valsava manoeuvre
Pulmonary ventilation

When you begin to exercise your respiratory rate also increases. This increase is influenced by the sympathetic nerves stimulating the respiratory muscles to increase the rate of breathing. The increased respiration rate allows more oxygen to reach the lungs and blood to be delivered to the muscles allowing the body to work easier without injury.

To meet the demands from the working muscles which need more oxygen, additional oxygen must be transported through the blood vessels. This blood is carrying carbon dioxide from the muscles and can increase the total stroke volume of the heart by 30 to 40 percent.

Tidal volume is the volume of air you breathe in a single breath.

Your lungs bring in fresh air with every breath; this amount is measured in part by the tidal volume. During exercise, your body's production of carbon dioxide goes up. Increasing tidal volume is one way for your lungs to accommodate the exhalation of this increased carbon dioxide load.

So as you begin to exercise your tidal volume increases because it is trying to accomidate for the amount of carbon dioxide being produced.

As the breathing rate increases the external intercostal muscles begin to contract more causing the ribs and sternum to move upwards and outwards.
The muscles of the neck pull up on the clavical and rib cage which allow the thoracic cavity to expand and allow maximum inhalation.

The vasalva maneuver is used to help increase intra-thoracic and intra-abdominal pressure.
Due to this increase in pressure, there is a decrease in venous return and reduced cardiac output. The heart rate then speeds up and vasoconstriction increases in order for the blood pressure to be maintained. If intense and held for long enough you may become lightheaded and even faint due to the lack of oxygen in the brain.
Pulmonary Ventilation (PV) is a term which describes the movement of air in and out of the lungs. The rate of PV is defined as the tidal volume multiplied by the number of breaths taken per minute.

As exercise begins the PV will immedietly increase due to the increasing demand of oxygen to the muscles in order for the body to exercise properly.
Neuromuscular Responses
Energy Systems
The reason adrenaline is released
Nervous control of the muscular system

The term muscle contraction in reference to the Muscular system would mean the musle would be shortening. Muscle contractions in reference to the neuromuscular system means muscle fibers generating tension. Muscle contractions are controlled by the nervous system, Voluntary and Involuntary.
The brain sends signals, in the form of action potentials, through the nervous system to the motor neuron that innervates several muscle fibers. A Neuromuscular junction is a place where the last motoneuron and the muscle cell meet.
As exercise begins the brain automatically sends signals towards the motor neuron which enables the muscles to contract ensuring tension.

Muscle spindles are small sensory organs with an elongated shape. It contains intrafusal fibers which are several small, specialized muscle fibers. They stimulate reflexively for a muscle contraction to prevent overstretching and muscle fiber damage, this is known as the stretch or myotatic reflex.
These twithes would be an anaerobic result of instant exercise. So as you start to exercise your brain sends these signals down and the muscle spindles do their job and try to prevent overstretching.
Muscle Spindles
Our muscle cells need an energy source to be able to contract during exercise. The first source of energy would come from the food we eat. A complex chemical process within your cells, called cellular respiration, converts the energy stored in the foods we eat into a form that is optimized for use at the cellular level of your muscles.
Creatine phosphate and lactic acid system

When exercise begins there is a large amount of ATP used. In order to quickly regenerate ATP and maintain high intensity activities, an enzyme known as creatine kinase breaks down creatine phosphate to creatine and a free phosphate with a net release of energy.The process is reversed to regenerate creatine phosphate. ATP is broken down to ADP and a free phosphate, of which the free energy is used to combine creatine and phosphate to form creatine phosphate.
Anaerobic glycolysis
Glycolysis simply means the breakdown (lysis) of glucose and consists of a series of chemical reactions that are controlled by enzymes. The anaerobic glycolytic system produces a lot of power, but not quite as much or as quickly as the ATP-PC system
Adrenaline is another word for the hormone epinephrine which is a part of the brain's response to exercise. Epinephrine increases the cardiorespiratory activity that facilitates exercise. It also has an affect on your metabolism and can improve your mood. So as exercise begins the brain automatically sends out this hormone in order for the body to work harder.
As we get more into exercising.

Read more: http://www.livestrong.com/article/536924-does-exercise-cause-an-adrenaline-rush/#ixzz2iLyNtjUK
Why does stroke volume increase?
Stroke volume increases according to how and what exercise you are doing because your body needs more oxygen and nourishment, which are both received from the blood. It also increases depending on the type of physical activity your are doing and your training level.
For example a person who is just taking part in jogging to stay fit would have a normal stroke volume of 50 ml at rest but when they begin jogging could raise to 120 ml. However an athlete that trains for long distance would have a resting stroke volume of 80ml and once they start running it would raise to approx 200 ml.
Adenosine triphosphate production

There are 3 systems which your body makes ATP for phosphorylization of creatine phosphate, aerobic and anaerobic respiration. Phosphorylization of CP happens immediately, but only lasts 15 seconds. It's the lease efficient, because it yields only 1 ATP/CP.

When exercise begins ATP and energy is needed, ATP is broken down using an enzyme also known as ATPase into ADP (Adenosine Diphosphate). This process breaks down the high energy Phosphate (P) bond and so provides energy for use by the body.

Stroke Volume
Heart rate activity response
Adrenaline is released as part of the sympathetic nervous system initiating the "fight or flight" response. It increase your heart rate in order to increase the amount of blood your heart beats each minute. The more blood that is flowing means a larger amount of oxygen your muscles will recieve. It also constricts your blood vessels, increasing your blood pressure and allows more blood to your muscles.
Due to this release of adrenaline the heart rate increases.
Heart rate anticipatory response
Investigate the initial responses of the Neuromuscular and Energy systems
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