Transcript Respiration
Respiratory System Anatomy & Physiology Function and Functional Anatomy Function: to supply the body with oxygen (O) and dispose it of carbon dioxide(CO2) Functional Anatomy: there are 2 zones of the respiratory system I. Conducting Zone II. Respiratory Zone Upper and Lower Respiratory Tracts I. Conducting Zone Function: to warm, cleanse and humidify incoming air Structures of the conducting zone – – – – – – Nose Pharynx Larynx Trachea Primary bronchii Lungs I. Conducting Zone: Nose A&P of the nose: – External nares: nostrils; where air enters – Nasal cavity: interior of the nose – Nasal septum: splits the n. cavity into 2; contains: • Mucosa: warms air and traps bacteria • Cilia: moves particles to throat to be digested • Olfactory receptors: nerve endings to detect smell I. Conducting Zone: Nose There are 3 main nasal structures: – Conchae: mucosa covered projections; increases surface area and creates air turbulence within nose – Palate: separates nasal and oral cavities • Hard palate: bony anterior section • Soft palate: non-bony posterior section – Paranasal sinuses: • Lightens the skull • Resonance chambers for speech • Produces mucus to drain into nasal cavity Paranasal Sinuses I. Conducting Zone: Pharynx AKA the throat Muscular passageway for both food and air About 5 inches long Houses the tonsils (clusters of lymphatic tissue) I. Conducting Zone: Pharynx 3 parts to the pharynx: – Nasopharynx: meets the auditory tube from ear; houses pharyngeal (adenoids) tonsils – Oropharynx: palantine tonsils @ end of soft palate – Laryngopharynx: lingual tonsils @ base of tongue I. Conducting Zone: Larynx AKA voice box Located inferior to pharynx Function: routes air and food into proper tubes Formed from 8 rigid hyaline cartilages and the epiglottis – Epiglottis: a flap of elastic cartilage; closes larynx while swallowing; open during breathing Larynx I. Conducting Zone: Larynx – Thyroid Cartilage: AKA adam’s apple; the largest of the 8 cartilaginous rings – Larynx holds the vocal folds (cords) • Vibrate with expelled air producing sound • Vocal folds surround glottis • Glottis: slit-like passageway in the larynx I. Conducting Zone: Trachea & Primary Bronchi Trachea – AKA the windpipe – ~4 inches long – Lined with ciliated mucus – Cilia beats to propel dust and bacteria away from lungs Primary Bronchi – There are 2; right and left – Runs from trachea to lungs – Air @ this point is warmed, humidified and cleansed I. Conducting Zone: Lungs Large paired organs Apex: narrow, superior region, lying posterior to clavicles Base: broad and inferior region; rests on diaphragm Lungs divided into lobes and fissures I. Conducting Zone: Lungs Right Lung: – 3 lobes – 2 fissures • Horizontal • Oblique Left Lung: – 2 lobes Lungs I. Conducting Zone: Lungs Visceral Pleura: serous membrane surrounding each lung Parietal Pleura: serous membrane lining the wall of the thoracic cavity – Both work to produce pleural fluid allowing for reduced friction b/n lung and wall; allows lungs to cling to wall II. Respiratory Zone Function: Where gas exchange takes place Structures of the respiratory zone: – Respiratory bronchioles – Alveolar ducts – Alveolar sacs – Alveoli II. Respiratory Zone: Bronchioles Respiratory Tree – Primary bronchi branch off into right and left lungs – They then further divide into secondary and tertiary bronchi---ends at bronchioles – Bronchioles: the smallest of conducting zone passageways leading to the respiratory zone Respiratory Tree II. Respiratory Zone: Alveoli Alveoli: small air sacs – Surrounded by alveolar sacs and connected by alveolar ducts—resembles grapes – Only site of gas exchange – Millions per lung – Walls made of squamos epithelial tissue Respiratory Membrane AKA Air-Blood Barrier – External surfaces of alveoli covered by pulmonary capillaries – Alveolar walls + capillary walls = respiratory membrane Respiratory Membrane: Gas Exchange Simple Diffusion: exchange of gasses across the vessel walls---DOWN the concentration gradient – Alveoli: holds air-CO2, O2 – Pulmonary Capillaries: holds blood CO2 O2 – Oxygen exchange occurs from alveoli to capillaries – Carbon dioxide exchange occurs from capillaries to alveoli Respiration Divided into 4 different events: 1. 2. 3. 4. Pulmonary Ventilation External Respiration Respiratory Gas Exchange Internal Respiration Respiration: Pulmonary Ventilation AKA breathing Definitions: – Atmospheric pressure: pressure outside the body – Intrathoracic/intrapulmonary pressure: pressure within the thoracic cavity/lungs Pressure is dependant on volume – Volume changes within thoracic cavity leads to pressure changes, leading to the flow of gases to equalize the pressure Respiration: Pulmonary Ventilation A. There are 2 parts to pulmonary ventilation: Inspiration – Inspiratory muscles: the diaphragm and intercostal muscles – Diaphragm contracts—moves inferiorly – Intercostals contract and lift rib cage; pushes sternum anteriorly Inspiration Respiration: Pulmonary Ventilation Inspiration continued – Intrapulmonary volume increases – Intrapulmonary pressure decreases • Pressure less than atm. pressure – Air moves into lungs from outside of body until pressure inside cavity = atm. pressure Respiration: Pulmonary Ventilation B. Expiration AKA exhalation – A passive process in healthy people – Inspiratory muscles relax, descending rib cage---lungs recoil – Thoracic and intrapulmonary volume decreases – Intrapulmonary pressure increases above atm. pressure—forcing air out of the body Respiration: Pulmonary Ventilation Forced Expiration – If respiratory passageways are impeded, expiration is an active process and muscles have to contract to decrease the volume of the cavity • Asthma • Bronchitis • Pneumonia Expiration Respiration: External Respiration The actual exchange of gas between alveoli and capillaries in the lungs – Oxygen from alveoli to capillaries – Carbon dioxide from capillaries to alveoli – Blood going back to heart and out to body is oxygen rich and carbon dioxide poor Respiration: Respiratory Gas Transport The transport of respiratory gases throughout the body – Oxyhemoglobin Complex: oxygen attaches to hemoglobin on RBC’s; transports oxygen through body – Some oxygen carried in plasma – Carbon dioxide transported in plasma as a bicarbonate ion (HCO3-); some carried on hemoglobin Respiration: Internal Respiration The exchange of gases occurring between blood in capillaries and tissue cells----opposite of exchange in lungs – Oxygen from capillaries to body cells – Carbon dioxide from body cells to capillaries – Venous blood back to heart is oxygen-poor and carbon dioxide-rich Internal and External Respiration Respiratory Volumes and Capacities Tidal Volume (TV): normal quiet breathing – ~500ml moves into and out of lungs with each breath Inspiratory Reserve Volume (IRV): amount of air taken in forcibly over TV – ~2100-3200 ml Respiratory Volumes and Capacities Expiratory Reserve Residual Volume: Volume (ERV): after strenuous amount of air expiration forcibly exhaled over – ~1200 ml air remains in lungs & cannot be tidal expiration – ~ 1200ml expelled voluntarily – Allows for continuous gas exchange between breaths Respiratory Volumes and Capacities Vital Capacity (VC): Dead Space the total amount of Volume: air that exchangeable air enters the resp. tract & remains in the – ~4800 ml in healthy males conducting zone— – VC =TV+IRV+ERV never reaches alveoli – ~150 ml Respiratory Control Centers Located in medulla and pons of brain stem – Inspiratory and expiratory centers in medulla keep respiration rate ~ 12-18 breaths per minute Receptors Influencing Respiration Chemoreceptors – Located in carotid and aorta arteries – Detect rising carbon dioxide levels and low oxygen levels in blood Pulmonary Stretch Receptors – Located in pulmonary airways and alveoli of the lungs Types of Breathing Eupnea: normal respiratory rate Dyspnea: labored/difficulty breathing Orthopnea: dyspnea relieved by sitting upright Apnea: momentary cessation of breathing Types of Breathing Types of Breathing Hyperventilation: rapid and deep breathing (too much oxygen/too little carbon dioxide) Hypoventilation: slow and shallow breathing (too little oxygen/too much carbon dioxide)