Respiratory and Motor System

• Training can also change the amount of muscle tissue in your body, while inactivity can cause the amount of muscle tissue to shrink.
• . Earth’s atmosphere is made up of approximately 78 % nitrogen and 21 % oxygen; the remaining gases, argon, carbon dioxide, and others, make up about 1 %
• Cells obtain energy through a chemical reaction called oxidation, in which organic compounds are broken down using oxygen
• It has been estimated that an average adult utilizes 250 mL of oxygen every minute while resting. Oxygen consumption may increase up to 20 times with strenuous exercise.
• Breathing, or ventilation, involves the movement of air between the external environment and the body
• The uptake of oxygen and the release of carbon dioxide by cells take place across a respiratory membrane.
• The term respiration can be used to describe all processes that supply oxygen to the cells of the body for the breakdown of glucose and to describe the process by which carbon dioxide is transported to the lungs for exhalation.
• breathing: the process of the exchange of air between the lungs and the environment, including inspiration and expiration
• respiratory membrane: the membrane where the diffusion of oxygen and other gases occurs between the living cells of the body and the external environment (the atmosphere or water)
• respiration: all processes involved in the exchange of oxygen and carbon dioxide between cells and the environment, including breathing, gas exchange, and cellular respiration
• External respiration takes place in the lungs and involves the exchange of O2 and CO2 molecules between the air and the blood.
• Internal respiration takes place within the body and involves the exchange of O2 and CO2 molecules between the blood and tissue fluids.
• The concentration of oxygen in cells is much lower than in their environment because cells continuously use oxygen for cellular respiration.
• Foreign particles are prevented from entering the lower respiratory tract by tiny hairs lining the nasal cavities that act as a filtering system.
• The nasal cavities warm and moisten incoming air and contain mucus, which traps foreign particles and keeps the cells lining the cavities moist.
• trachea: the windpipe
• cilia: tiny hairlike structures found on some cells that sweep away foreign debris
• epiglottis: the structure that covers the glottis (opening of the trachea) during swallowing
• larynx: the voice box
• glottis: opening to the trachea
• Two openings branch from the pharynx: the trachea, or windpipe, and the esophagus, which carries food to the stomach.
• . Mucus-producing cells, some of which are ciliated, line the trachea. The mucus traps debris that may have escaped the filters in the nasal passage.
• debris is swept by the cilia (singular: cilium) from the windpipe back into the pharynx
• The nasal cavities open into an air-filled channel at the back of the mouth called the pharynx
• The wall of the trachea is supported by bands of cartilage, which keep the trachea open
• An enlarged segment of cartilage (the larynx) supports the epiglottis, a flaplike structure that covers the glottis, or opening of the trachea, when food is being swallowed.
• Food or liquid entering the trachea stimulates the cilia, and particles too large to be swept out of the respiratory tract are usually expelled by a second more powerful reflex: a violent cough.
• Air from the pharynx enters the larynx, or voice box, located at the upper end of the trachea. The larynx contains two thin sheets of elastic ligaments that form the vocal cords. The vocal cords vibrate as air is forced past them.
• Your larynx is protected by thick cartilage commonly known as the Adam’s apple. Following puberty, the cartilage and larynx increase in size and thickness, more so in males than females.
• Inflammation of the vocal cords causes swelling and produces lower-frequency vibrations. Should the infection become severe and result in a condition referred to as laryngitis, you may temporarily lose your voice.
• . The hiccup sound is produced when air is taken in as the glottis closes
• bronchi: the passages from the trachea to the left and right lung
• bronchiole: the smallest passageways of the respiratory tract
• alveoli: sacs of the lung in which gas exchange occurs
• Inhaled air moves from the trachea into two bronchi (singular: bronchus), which, like the trachea, contain bands of cartilage
• The bronchi carry air into the right and left lungs, where they branch into many smaller airways called bronchioles.
• Unlike the trachea and bronchi, the bronchioles do not contain cartilaginous bands. Muscles in the walls of the bronchioles can decrease their diameter
• Any closing of the bronchioles increases the resistance of air movement and can produce a wheezing sound.
• Air moves from the bronchioles into tiny sacs called alveoli (singular: alveolus). Measuring between 0.1 and 0.2 µm (micrometres) in diameter, each alveolus is surrounded by capillaries
• . In the alveoli, gases diffuse between the air and blood according to concentration gradients