Exercise affects a number of biological activities that take place throughout the body. These include changes in the muscles, lungs, heart, brain, joint and bones, among others. During exercise the muscles need ATP and glucose for its contraction and relaxation. The body creates more ATP by increasing the demand for oxygen, which results in increased breathing and increase in the pumping of the blood to the muscles by the heart (Rivera-Brown and Frontera 2012).
With increase in exercise, the muscles require more oxygen and as a result, the lungs start functioning rapidly and the respiratory rate increases. The heart rate also increases to supply more blood to the muscles. The increase in blood flow because of exercise also affects the brain and helps it to function effectively. Exercising promotes the growth of new cells in the brain, which in turn helps to boost learning and memory (Thomas et al. 2012). Exercises also help to maintain a healthy bone mass.
This report gives a brief description of each of the systems, followed by the effects of exercise on each of these systems.
The musculoskeletal system helps to provide support, form, movement and stability to the entire body. It consists of the bones, muscles, joints, tendons, ligaments, cartilage and other connective tissues that binds the organs and tissues together.
Bones of the human skeleton
The different types of bones of the human skeleton are the long bones, short bones, flat bones, irregular bones, sesamoid bones and sutural bones. The long bones include the femur, tibia, fibula, ulna, humerus and radius. Long bones consists of a shift with variable number of extremities, are curved, thereby contributing to the mechanical strength. The short bones include scaphoid bones, hamate bones, lunate bones, cuboid bones, first and second cuniform bones and tarsal bones. The function of the cube shaped short bones is to provide stability and support with very little to negligible movement. The flat bones consists of the cranialbones (frontal and parietal bones), sternum, ribs and the scapulae. The flat bones are thin and provide protection to soft tissues that lie underneath or are enclosed by them. The irregular bones include the atlas and axis bones, hyoid, sphenoid, zygomatic and other facial bones. The irregular bones do not have any definite shape and is responsible for providing mechanical support. The sesamoid bone consists of the patella. They develop in tendons, which undergo physical stress, friction and tension. The sutural bones are small and located in the sutural joints in between the bones of the cranium (Hillson 2016).
Characteristics of joints
The 3 main types of joints of the human body are the fibrous, cartilaginous and the synovial joints. The fibrous joints are immoveable and synarthrodial. They are connected to each other by dense connective tissues, mainly collagen. They have no cavity. The 3 types are sutures, syndesmoses and gomphoses. The cartilaginous joints form connections between the bones held together by cartilage. They are semi-moveable and are of 2 types, namely synchondroses and symphyses. The synovial joints are freely moveable. They have a synovial capsule, synovial membrane that is responsible for secreting the synovial fluid and the hyaline cartilage, which provides protection to the ends of the articulating bones (Sekiya et al. 2015).
The types of synovial joints are the hinge, pivot, ball and socket, saddle, condyloid and gliding joint. The possible movements of the hinge joints (elbow, knee) include flexion and extension, those of the pivot joints (atlas, axis) are rotation, those of the ball and socket joints (shoulder, hip) are flexion, extension, adduction, abduction, internal and external rotation. The movements of the saddle (thumb) and condyloid joints (wrist) are flexion, extension, adduction, abduction and circumduction. The movements of the gliding joint (intercarpal joints) include gliding movements (Sokoloff 2014).
Functions of skeletal muscle pairs
The skeletal muscle pairs consist of an agonist and antagonist. The agonist is the prime mover and an antagonist functions opposite to that of the agonist. One pair is the biceps and triceps brachii located in the anterior and posterior compartments of the arm. The biceps brachii flexes, while the triceps brachii extends the forearm. Another pair is the hamstrings and the quadriceps femoris. The hamstrings consist of 3 muscles in the posterior part of the thigh compartment, while the quadriceps femoris consist of 4 muscles in the anterior compartment of the thigh. The hamstring flexes, while the quadriceps femoris extends the legs (Jarmey and Sharkey 2016).
Skeletal, cardiac and smooth muscles
The skeletal muscles carry out voluntary movement. They vary in size, shape and fiber arrangements. Skeletal muscle consists of large number of muscle fibers wrapped within connective tissue. The connective tissue sheath is called epimysium. Fascia is the connective tissue present outside the epimysium. The bundle sof muscle fibers or fasciculus are surrounded by perimysium. Each muscle cell is surrounded by endomysium. The skeletal muscle fiber is a cylindrical and single muscle cell. The connective tissues provide protection and support against forces of contraction. It consists of blood vessels and nerves that helps in the contraction (Frontera and Ochala 2015).
Cardiac muscles or myocardium is a part of the heart. It consists of a layer of myocardium in between the endocardium and epicardium. The endocardium lines the cardiac chambers and valves. Epicardium protects, lubricates and surrounds the heart. The myocardium consists of cardiomyocytes. The cardiac muscles contracts in order to squeeze the blood out of heart called systole and then relaxes called diastole. The atria contract to push the blood to the ventricles, while the ventricles contract and push the blood out of the heart (Canale, Campbell and Smolich 2012).
Smooth muscles carry out involuntary movements. They are not striated and the fibers are tapered and small. The smooth muscle fibers have a nucleus at the central position. Smooth muscle contractions carry out constrictions of the surrounding vessels. This is a part of the gastrointestinal system. It also helps in movements of fluids throughout the body and elimination of undigested matter (Campbell and Campbell 2012).
Effect of exercise on the musculoskeletal system
Exercise has a positive influence on the musculoskeletal system. It results in increased lean muscle mass, which results in improvements in energy metabolism, improved vascularity, posture and support to the entire body, maintenances of bone density, balance and coordination. It also improves the range of joint motions and improves metabolic rates. Helps to keep the joints supple and increased secretions of synovial fluid helps in joint motions. Exercise increases the metabolic activity of the muscles, thereby helping in burning calories and gaining lean body mass (Vincent, Raiser and Vincent 2012).
Figure 1: Effect of exercise on the musculoskeletal system
(Source: Pedersen and Febbraio, 2012)
The respiratory system is a complex system that helps in the inhalation and exhalation of respiratory gases like oxygen and carbon dioxide.
Anatomy and function
The respiratory system consists of the biological structures like the nose and nasal cavity, pharynx, mouth, trachea, larynx, bronchi, bronchioles, lungs and the respiratory muscles. The nose provides protection and support to the nasal cavity. The hairs of the mucous membranes trap the harmful agents present in the air (Peters 2013). It also involves warming the outside air before entering the respiratory tract and at the time of exhalation, the heat from the warm air is returned to the nasal cavity. The mouth helps to supplement the air inhaled by the nose and functions as an alternative. The pharynx consists of nasopharynx, oropharynx and laryngopharynx. It acts as an intermediate between the nasal cavity and larynx or esophagus. The air from the laryngopharynx is diverted to the larynx by the epiglottis. The larynx connects the laryngopharynx to the trachea. The larynx consists of the epiglottis, thyroid and cricoids cartilage and the vocal folds. These cartilages offer protection and support to the vocal folds and the larynx. The vocal folds help in the development of sound. The trachea consists of hyaline cartilage rings that keeps the trachea open for air intake. The open end of the trachea faces the esophagus and this in turn helps in permitting food chunks to pass through. The trachea connects the larynx to bronchi and filters the air that enters the lungs. The epithelium traps harmful particles. The lower portion of the trachea branches into the primary bronchi. Then in the lungs they branch into smaller bronchi. The secondary bronchi carry air to the lungs and split into the tertiary bronchi. The tertiary bronchi splits into bronchioles. They control the flow of air that enters the lungs and also traps harmful contaminants. The lungs consist of innumerable sacs called alveoli. The respiratory gases present in the air that enters the alveoli can be exchanged with the blood running through the capillaries. The muscles surround the lungs and help in the continuous inhalation and exhalation of air (Ionescu 2013).
Structure of alveoli and its function
The lungs consist of microscopic branches called respiratory bronchioles. These in turn are connected to the alveolar ducts. The end of the alveolar ducts consist of alveolar sacs, each containing 20-30 alveoli, which are 200-300 micrometer in diameter. The alveolar membranes are one cell thick and are in contact with capillaries. The large surface area of the alveoli along with the thin membranes allows easy diffusion of gases across alveolar walls. The oxygen present in the inhaled air undergoes diffusion through the alveolar walls and capillaries into the red blood cells, which in turn carries the oxygen to the body tissues. The carbon dioxide from the body is returned to the alveoli, which then diffuses though the respiratory membranes and capillaries into the air space to be exhaled (Lopez-Rodriguez and Pérez-Gil 2014).
Figure 2: Lungs and alveoli
(Source: Hogan et al. 2014)
Effects of exercise on ventilation and relation to homeostasis
The resting values of ventilation ranges from 5-6 liters per minute and on exercising these values increase to 100 liters per minute. Ventilation rates increases proportionally with increase in the rate of exercises. The rates of oxygen consumption also increase with the increase in exercise rates. The resting oxygen consumption of a healthy young male is 250 ml per minute and high endurance exercises can result in oxygen consumption of 5000 ml per minute. The rise in pulmonary ventilation is caused as a result of increased respiratory rate and tidal volume and creates a balance between the increase in uptake of oxygen with release of carbon dioxide. Ventilation suddenly increases at the onset of exercise and then is followed by a gradual increase. Exercise helps to increase energy consumption by the muscles and also activates the energy generating reactions, thereby helping to maintain homeostasis. The increased heart rate also helps to deliver oxygen to the cells of the body to maintain a balance in the oxygen levels in the body. The heat generated due to exercise helps to maintain a balance in the body temperature, while sweating helps to remove that heat (Lekeux, Art and Hodgson 2013)
Circulatory and cardiovascular system
Types of blood vessels
The human body consists of three types of blood vessels. These are arteries, veins and capillaries. The arteries are responsible for carrying blood away from heart. The arteries divide into arterioles, which divide to form capillaries. The inner wall of the arteries provides frictional resistance to the flow of blood. The middle layer stretches at the time of heart beats, while the outer layer acts as a thick covering. The pressure is maintained by elastic stretch and recoil. The veins return the blood to the heart. The systemic veins are responsible for carrying deoxygenated blood. The superior and inferior venacava return the blood from the body to the heart. The vein has a inner layer tunica intima, a thick outer layer called tunica adventitia. The blood flow through the veins is slower due to the large area as compared to arteries. The smallest blood vessels are the capillaries. Exchange of gases, wastes and nutrients take place in the capillaries between the blood and body tissues. Double circulation involves the presence of two loops, one loop carries oxygenated, while the other carries deoxygenated blood (Abramson 2013).
Structure of heart
The heart controls the circulatory system and helps to pump blood throughout the body. The heart consists of a dark red muscle on the outside and attached to the venacava, pulmonary artery and vein and the aorta. The internal part of heart consists of the atria and ventricles. The atrioventricular valves separates the atria from the ventricles, while the semilunar valves separate the ventricles from the pulmonary artery and aorta. The atrial walls are thin, while the ventricular walls are thick (Glass, Hunter and McCulloch 2012).
The cardiac cycle consists of the diastole and the atrial and ventricular systole. During the diastole, the heart is filled with blood. The blood flows from the venacava and pulmonary veins to the atria and ventricles. During the atrial systole, the atria undergoes contraction thereby pumping more blood to the ventricles. During the ventricular systole, the ventricles undergo contraction and the atrioventricular valves are kept shut by the blood, thereby preventing blood to enter the atria. When the pressure increases, the semilunar valves open, forcing the blood out of heart and into arteries. The subsequent decrease in pressure, causes the semilunar valves to shut and the atrioventricular valves to open. The electrical system of the heart generates signals that helps the heart to beat. This heartbeat helps to pump the blood throughout the whole body. The electrical system includes the sinoatrial, atrioventricular node and the His-purkinje system. The electrical signals causes the heart chambers to undergo contraction and relaxation. This is highly essential during the cardiac cycle.
Composition of blood and associated functions
The composition of blood consists of plasma, red and white blood cells and platelets. The red blood cells carry oxygen to the body and carbon dioxide to the lungs to exhale, the white blood cells help to fight infection and are a part of the immune system, while the platelets are required for clotting. The lymphatic system consists of the lymph fluid having white blood cells that helps to fight infections and remove unwanted toxins from the body (Bain 2014).
Effects of exercise on the cardiovascular system
The effects of exercise on the cardiovascular system involves increased blood circulation, lowering of resting heart rate, lowered blood pressure, improvement of blood flow, decrease in the number of varicose veins, increases the red blood cells, diminishes the level of stress related hormones and increases the lining of the blood vessels (Lavie et al. 2015).
Figure 3: Effect of exercise on the cardiovascular system
(Source: Golbidi and Laher 2012).
This report describes the effect of exercise on the musculoskeletal system, respiratory system and the cardiovascular system. The effects of exercise on the musculoskeletal system includes increased blood flow, increased muscle size, muscle coordination and blood supply. The effects of exercise on the respiratory system includes increased rates of breathing, increased oxygen uptake, increased blood supply to the lungs, increased functional and vital capacity, increased diffusion of respiratory gases like carbon dioxide, which is exhaled. The effect of exercise on the cardiovascular system includes increased heart rate and blood flow. Thus, exercise is highly important in order to maintain the proper functions of the body.
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