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Respiratory System

Respiratory System. Introduction. The respiratory system shares responsibility with the cardiovascular system for supplying the body with oxygen and disposing of carbon dioxide. Oversees gas exchanges between blood and external environment. Organs of respiratory system. Nose Pharynx Larynx

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Respiratory System

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  1. Respiratory System

  2. Introduction • The respiratory system shares responsibility with the cardiovascular system for supplying the body with oxygen and disposing of carbon dioxide. • Oversees gas exchanges between blood and external environment

  3. Organs of respiratory system • Nose • Pharynx • Larynx • Trachea • Bronchi and their smaller branches • Lungs • Alveoli (contained in lungs)

  4. The Nose • Only externally visible part of respiratory system • Air enters through nostrils (external nares) • Interior of nose = nasal cavity, divided by nasal septum • Olfactory receptors (for sense of smell) are located in the mucosa in the upper slitlike part of the nose • Respiratory mucosa = remaining mucosa in the nose  warms and moistens the air as it flows past, traps bacteria and other foreign debris

  5. The Nose • Nasal mucosa creates a current using the cilia on cells that moves contaminated mucus towards the pharynx (throat) where it gets swallowed and digested by stomach juices. • In cold weather, the cilia get sluggish and slow  mucus accumulates in the nasal cavity and starts to drip outwards  “runny nose” • Nasal cavity is separated from oral cavity by hard and soft palate  cleft palate = bones failed to fuse properly, results in breathing, chewing, and speaking problems

  6. The Nose • Paranasal sinuses = surround nasal cavity, located in frontal, sphenoid, ethmoid, and maxillary bones • Sinuses lighten the skull, act as resonance chambers for speech, and produce mucus, which drains into nasal cavity • Blowing your nose creates a suctioning effect which drains the sinuses

  7. The Pharynx • The throat  passage way for food and air • Directly connected to nose through internal nares • Auditory tubes = drain the middle ear, open into the pharynx • Sore throats (or other throat infections) are often followed by ear infections • Tonsils are also found in pharynx

  8. The Larynx • The “voice box”  Below the pharynx, helps route air and food into proper channels • Formed by eight rigid hyaline cartilages  largest one is the shield shaped thyroid cartilage, usually called the Adam’s apple • Epiglottis = “guardian of the airways”  does not restrict air flow when we are not swallowing, but when we swallow, it forms a lid over the opening of the larynx • If anything other than air enters larynx, the cough reflex is triggered (unless unconscious) • Vocal cords = folds in the mucus membrane in the larynx  vibrate with expelled air, which allows speech

  9. The Trachea • The windpipe = connected to larynx, lined with ciliated mucosa • The cilia continuously beat in the opposite direction to incoming air, which moves mucus that is loaded with dust and other debris away from the lungs and to the throat to be swallowed or spit out. • Trachea is the only way for air to enter lungs  blocked trachea = death • Heimlich maneuver uses lungs to “pop” obstruction out of trachea

  10. The Primary Bronchi • Right and left branches from trachea, attach to lungs • Right bronchus is wider, shorter and straighter  more foreign objects get lodged on the right side • By the time it reaches the bronchi, air is warm, mostly cleansed of impurities, and well humidified • Bronchioles = smaller subdivisions of bronchi that lead to the air sacs

  11. The Lungs • Occupy most of thoracic cavity • Surface is covered by pulmonary pleura, walls of thoracic cavity are lined by parietal pleura • The pleural membranes produce pleural fluid, which allows lungs to slide over thorax wall during breathing movements and causes the two pleural layers to cling together. • Alveoli = air sacs connected to bronchioles, resemble bunches of grapes

  12. The Lungs • The walls of alveoli are one-cell thick • Alveolar pores connect neighboring air sacs, providing alternate routes for air to reach alveoli whose bronchioles are clogged. • External surfaces of alveoli are covered by a “cobweb” of pulmonary capillaries  respiratory membrane (air blood barrier) • Gas exchange occurs through diffusion • Alveoli are coated with surfactant, a lipid, that allows diffusion to occur

  13. How do you breathe? • Gas travels from areas of high pressure to areas of low pressure • Atmospheric pressure = pressure outside body • Intrapulmonary pressure = pressure inside lungs • Intrapleural pressure = pressure in intrapleural space (always negative)

  14. How do you breathe? • Pulmonary ventilation = movement of air into and out of the lungs (breathing) • Inspiratory muscles contract  volume inside lungs increases  pressure decreases  air rushes in (inspiration) • Inspiratory muscles relax  lungs recoil  air rushes out (expiration)

  15. Nonrespiratory air movements • Voluntary or reflex activities that move air into or out of the lungs • Examples: • Coughing • Sneezing • Laughing • Crying • Hiccuping • Yawning

  16. Respiratory volumes and capacities • Tidal volume (TV) = amount of air in a normal, quiet breath, usually about 500 mL of air • Inspiratory reserve volume (IRV) = greatest amount of air a person can inhale over TV, usually between 2100 and 3200 mL • Expiratory reserve volume (ERV) = greatest amount of air a person can forcibly exhale, usually about 1200 mL • Residual volume = air that cannot be forcibly exhaled, allows gas exchange to continue between breaths, about 1200 mL • Vital capacity (VC) = total amount of exchangeable air, TV + IRV + ERV, around 4800 mL

  17. Respiratory volumes and capacities

  18. External Respiration, Gas Transport, and Internal Respiration • External respiration = exchange of gases between alveoli and the blood, blood picks up oxygen and releases CO2 • Internal respiration = exchange of gases between systemic capillaries and tissue cells, blood picks up CO2 and releases oxygen • Gas moves through diffusion  high to low concentration • Most oxygen is transported by attaching to hemoglobin, but some is carried as dissolved oxygen in the plasma • Most CO2 is transported in the plasma as HCO3-, but some is carried by attaching to hemoglobin

  19. How is respiration controlled? • Nervous control – centers of control in medulla and pons • Physical factors – Body temperature, exercise, speech, etc. • Volition – Conscious control (to a degree) • Emotional factors – fear, anger, excitement • Chemical factors – CO2 levels in blood, oxygen levels

  20. Some respiratory disorders • Chronic obstructive pulmonary disease (COPD) = emphysema and chronic bronchitis • Emphysema = alveoli are enlarged and/or destroyed, lungs lose elasticity • Chronic bronchitis = excessive mucus production, which collects in and blocks lower respiratory pathways • Lung cancer • Pneumonia • Birth disorders = cleft palate, cystic fibrosis • Respiratory tract infections

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