PE CRS
4 Summary
Cardiovascular system structures
• The cardiovascular system has three main structures that help carry out its functions:
o heart
o blood vessels
o blood.
Cardiovascular system functions
• The cardiovascular system has five main functions:
o to circulate blood
o to transport water, oxygen and nutrients
o to transport wastes
o to help maintain body temperature
o to help fight disease.
• The heart is an involuntary muscle that pumps blood throughout the cardiovascular system. It has four chambers, two atria and two ventricles, a septum that divides the heart into two pumps and valves at the entrances of structures to allow only a one-way flow of blood.
• The heart works via contraction and relaxation of the atria and ventricles. This is known as the cardiac cycle.
• The three types of blood vessels are arteries, capillariesand veins.
o Arteries carry blood away from the heart.
o Capillaries are the site of exchange of gases between the cells and the cardiovascular system.
o Veins return blood to the heart.
• Blood circulation occurs via two main circuits:
o the systemic circuit (the body)
o the pulmonary circuit (the lungs).
Role of the cardiovascular system in thermoregulation
• Thermoregulation is the maintenance of body temperature and heat exchange that occurs between the body and the environment.
• The cardiovascular system assists thermoregulation through the redirection of blood flow via the expanding of blood vessels (vasodilation) to increase heat loss or the reduction in size of blood vessels (vasoconstriction) to reduce heat loss.
Responses of the cardiovascular system
• There is a direct relationship between heart rate, stroke volume and cardiac output in response to increased demands to produce energy during exercise across a range of varying intensities.
• The cardiovascular system adapts to the onset of exercise via increases in heart rate, stroke volume, cardiac output, systolic blood pressure, arteriovenous difference (a-VO2 diff.), blood flow and redistribution of blood flow.
• Key terms
• acute responses the body’s immediate, short-term responses that last only for the duration of the activity and for a short time afterwards (recovery)
• arteries large, thick-walled blood vessels that carry blood away from the heart
• arterioles small blood vessels that branch off from arteries and extend to capillaries
• arteriovenous oxygen difference (a-VO2 diff.) the difference between the concentration of oxygen in the arterial blood and the concentration of oxygen in the blood in the veins. This is measured in mL/100 mL of blood.
• atria the two upper chambers of the heart. They receive blood from the veins and pump it into the lower chambers (ventricles).
• blood the fluid circulated by the heart around the body. It consists of plasma, red and white blood cells, and platelets.
• blood vessels a transport network of arteries, capillaries and veins that carries nutrients and waste around the body
• capillaries tiny blood vessels in the cardiovascular system between the ends of the arterioles and the venules. They are the site for the exchange of gases between the cells and the cardiovascular system.
• cardiac cycle the movement of blood through the heart in one heartbeat. It consists of alternate systole and diastole of the atria and the ventricles.
• cardiac output (Q̇) the amount of blood ejected from the left ventricle of the heart per minute. It is the product of stroke volume (SV) multiplied by heart rate (HR), so Q̇ = SV × HR, and is measured in litres per minute (L/min).
• cardiovascular system the heart and blood vessels circulate blood throughout the body, delivering water, oxygen and nutrients to cells, and removing waste products such as carbon dioxide
• coronary arteries the arteries that supply oxygen and nutrients to the cardiac muscle (heart)
• deoxygenated oxygen-poor (carbon dioxide-rich) (blood)
• diastole a relaxation of the heart muscle
• heartbeat one contraction and relaxation of the heart muscle
• homeostasis a constant internal environment for optimal functioning of the body and its systems
• hyperthermia a rise in the body’s core temperature above 37.5–38.3 °C
• hypothermia a reduced core body temperature below 35 °C
• oxygenated oxygen-rich (blood)
• precapillary sphincters one-way valves that control blood flow within capillaries
• pulmonary circulation the arteries and veins that feed blood from the heart to and from the lungs where blood is oxygenated
• steady state the state in which oxygen supply equals oxygen demand and energy is being supplied aerobically
• stroke volume (SV) the amount of blood ejected from the left ventricle with each heartbeat (contraction) of the heart. It is measured in millilitres per beat (mL/beat).
• systemic circulation the arteries and veins that feed blood from the heart to the whole body and back to the heart again for reoxygenation
• systole a contraction of the heart muscle, specifically the ventricles
• systolic blood pressure the blood pressure recorded as blood is ejected during the contraction phase of the heart cycle. It is the higher of the two blood-pressure values.
• thermoregulation the maintenance of core body temperature within a narrow range
• vasoconstriction a process whereby blood vessels narrow or constrict, causing a decrease in blood flow
• vasodilation a process whereby blood vessels increase their diameter, causing an increase in blood flow
• veins blood vessels that carry deoxygenated blood and waste products from the body’s cells back to the heart
• venous pooling a collection of blood in the leg veins when high-intensity activity stops too suddenly
• ventricles the two lower chambers of the heart. They receive blood from the atria and pump it to the lungs (right ventricle) and to the body (left ventricle).
5 RESPIRATORY SYSTEM
• The respiratory system — structure and functions
• The respiratory system brings oxygen into the body and removes carbon dioxide from the body.
• The conducting system of the respiratory system includes the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and alveoli.
• The diaphragm contracts and relaxes to aid breathing.
The respiratory system — mechanics of breathing and gaseous exchange
• Inspiration is when the lungs take in air, while expiration is when air is forced out of the lungs.
• Gas exchange occurs at the alveoli and capillaries, and at the capillaries and muscles, and involves the movement of oxygen and carbon dioxide from areas of high concentration to areas of low concentration.
• Everyone has different lung volumes, and this affects their capacity for holding and expelling air.
• Vital capacity measures the maximum amount of air that you can breathe out after a maximum inhalation.
• Maximum oxygen uptake (VO2 max) is the maximal amount of oxygen that can be used by the body in 1 minute.
Responses of the respiratory system to physical activity
• The respiratory system adapts to the onset of exercise via increases in respiratory rate, tidal volume, ventilation, pulmonary diffusion and oxygen uptake by the muscles.
Summary of the interaction of the cardiovascular system and respiratory systems during physical activity
• The heart, a key component of the cardiovascular system, plays a major role in receiving oxygen-rich blood from the lungs (respiratory system) and pumping it throughout the body. It then circulates deoxygenated, CO2-rich blood back to the lungs to be exhaled.
• The respiratory system functions to inhale oxygen into the lungs and diffuses it into the bloodstream via the alveoli. This oxygen is then transferred to the cardiovascular system and delivered to body tissues from the capillaries.
• Both the cardiovascular and respiratory systems are essential for the efficient delivery of oxygen to tissues and the removal of carbon dioxide, which is crucial for maintaining the body’s metabolic processes.
Key terms
• diffusion the movement from a higher concentration to a lower concentration
• expiration the movement of air out of the lungs to the external environment (breathing out)
• inspiration the movement of air from the external environment into the lungs (breathing in)
• maximum oxygen uptake (VO2 max) the maximum amount of oxygen per minute that can be taken in, transported to and used by the working muscles to produce ATP (adenosine triphosphate)
• pulmonary diffusion the process to describe the exchange of gases in the lungs
• respiratory rate (RR) the amount of breaths per minute
• respiratory system the lungs and associated structures responsible for gas exchange in the body, bringing air into the body and removing waste products
• tidal volume (TV) the amount of air breathed in and out in one breath
• ventilation (V) the amount of air that is inspired and expired during 1 minute
• vital capacity the maximum amount of air that can be expired after a maximal inspiration
6. Summary
Impact of aerobic exercise on the cardiorespiratory system
• Performance benefits of a more efficient cardiorespiratory system include not having to work as hard at the same intensity during aerobic activity or being able to work at a higher intensity aerobically for longer, delaying fatigue.
• Aerobic exercise involves repetitive movements, such as walking or swimming, which increase the rate of oxygen delivery from the lungs to the blood. This allows for greater efficiency of the cardiorespiratory system.
• Long-term physiological changes to the cardiorespiratory system occur when exercise is done regularly, such as an increase in heart size and lung volume.
Permitted substances and methods
• Training methods to enhance the functioning of the cardiorespiratory system include aerobic training methods, such as continuous training, fartlek training, long-interval and high-intensity interval training, as well as altitude training.
• Altitude training is a permitted training method that induces physiological changes to enhance the oxygen-carrying capacity of the blood, thus increasing the delivery of oxygen to the muscles. This training can occur at actual altitude (greater than 1500 metres above sea level) or in specifically designed chambers or rooms that simulate altitude.
Prohibited substances and methods
• Prohibited methods used by athletes to enhance performance include EPO, blood doping, gene doping and beta blockers.
• EPO and blood doping increase the red blood cell count, creating more sites to carry oxygen, which results in better oxygen transportation and a higher rate of aerobic energy production.
• The use of beta blockers is prohibited in precision sports such as archery and shooting as they can increase the competitor's accuracy and steadiness, and reduce body tremors and pre-competition anxiety.
• Gene doping involves the use of substances or techniques to manipulate cells or genes, with the potential to improve athletic performance. This technology is rapidly transforming various fields.
Ethical and sociocultural influences
• There are a variety of reasons why athletes may feel the pressure to use performance-enhancing substances. Sociocultural influences on athletes’ decision-making include income; education; family and peers; the influence of coaches and sporting organisations; cultural norms in society or the particular sporting culture; and national and political ideologies.
• When deciding if a substance or method is permitted from an ethical standpoint, it is important to uphold the integrity of the sport by keeping a fair and even playing field as well as prioritising the health of the athletes.
6.Key terms
aerobic exercise sustained physical effort which increases the rate that oxygen is inhaled and passed from the heart to the bloodstream
aerobic training training that specifically targets the aerobic energy system and refers to a type of repetitive, rhythmical movement
altitude training involves training at levels greater than 1500 metres above sea level to induce physiological changes that enhance the oxygen-carrying capacity of the blood
beta blockers drugs that block adrenaline hormones from binding to receptors on nerves, reducing the effect they have on the heart and blood vessels
blood doping the process of infusing extra human blood (red blood cells) into an athlete’s body prior to performance
continuous training continuous, submaximal (70–85 per cent HR max) activity lasting longer than 20 minutes
CRISPR-Cas9 a gene editing tool that allows scientists to selectively modify the DNA of living organisms. It makes it possible to switch genes on and off and correct errors in the genome.
deoxyribonucleic acid (DNA) molecule that carries genetic information for the development and functioning of an organism
erythropoietin (EPO) a naturally occurring hormone secreted by the kidneys that stimulates the production of red blood cells. Can also be produced synthetically.
fartlek training continuous training involving changes of intensity to work both the aerobic and anaerobic energy systems
gene doping the use of substances or techniques to manipulate cells or genes to improve athletic performance
haemoglobin protein responsible for transporting oxygen in red blood cells
high-intensity interval training (HIIT) training that involves repeated bouts of high intensity efforts followed by varying periods of complete rest or recovery at a lower intensity
hypoxic means that a low level of oxygen is available
long-interval training training that consists of intervals of work followed by equal intervals of rest or recovery to develop the aerobic energy system
maximum oxygen uptake (VO2 max) the maximum amount of oxygen per minute that can be taken in, transported and used by the body for energy production
nucleic acids nucleotides that are the building blocks of DNA
nucleic acid analogues compounds that are structurally similar to naturally occurring DNA
permitted officially allowed
physiological adaptations the physical changes of the body's cardiovascular, respiratory and muscular systems due to regular exercise, over a period of time
pulmonary diffusion the movement of oxygen and carbon dioxide from a high concentration to a low concentration between the alveoli and the surrounding capillaries
sociocultural relating to the social and cultural norms prevalent in society
