Respiratory System

Respiratory System – Fig. 14-1 Includes the passages that transport air to and from the lungs, and the air sacs in which gas exchange occurs. Respiration is the entire process by which gases are exchanged between the atmosphere and the body cells. http://www.youtube.com/watch?v=o2OcGgJbiUk&feature=related (Overview of respiratory system) (Don’t get confused with cellular respiration which is the breakdown of food to produce chemical energy.)

Organs of the Respiratory System Upper respiratory (outside thorax) – nose, larynx, & pharynx Lower respiratory (within thorax) – trachea, bronchial tree, and lungs Nose Supported by bone & cartilage Nostrils provide entrances for air

Organs of the Respiratory System Nasal Cavity (space behind the nose) – Fig. 14-4 Divided medially by the nasal septum Nasal conchae divide the cavity into passageways & help increase the surface area of the mucous membrane Mucous membrane (Fig. 14-2) – filters, warms & moistens incoming air; particles trapped in the mucus are carried to the pharynx by ciliary action & are swallowed

Organs of the Respiratory System

Organs of the Respiratory System Cilia Pseudostratified epithelium Submucosa Mucous gland

Organs of the Respiratory System Sinuses – Fig. 14-3 Spaces in the bones of the skull that open into the nasal cavity Lined with mucous membrane that is continuous with the lining of the nasal cavity Function mainly to reduce weight of skull, they also serve as resonant chambers that affect the quality of the voice

Organs of the Respiratory System

Organs of the Respiratory System Pharynx (throat) Located behind the mouth and between the nasal cavity and the larynx Functions as a common passage for air and food Aids in creating vocal sounds

Organs of the Respiratory System

Organs of the Respiratory System Larynx – Fig. 14-5 Enlargement at the top of the trachea Serves as passageway for air & helps prevent foreign objects from entering the trachea Composed o muscles & cartilage Contains the vocal cords which produce sounds by vibrating as air passes over them Pitch of sound is related to the tension of cords Intensity is related to the force of the air passing over the cords Glottis (space between vocal cords) & epiglottis help prevent food & liquid from entering the trachea

Organs of the Respiratory System

1- vocal cords; 2 – vestibular fold; 3 – epiglottis; 4 – glottis; 5 – cartilage; 6 – sinus piriformis; 7 – base of the tongue

Organs of the Respiratory System Larynx – Fig. 14-5 http://www.youtube.com/watch?v=ajbcJiYhFKY (vocal cords)

Organs of the Respiratory System Trachea – Fig. 14-6 Extends into the thoracic cavity in front of the esophagus Divides into the right and left bronchi Mucous lining continues to filter incoming air Wall is supported by incomplete (C shaped) cartilaginous rings; keeps trachea from collapsing

Organs of the Respiratory System

Organs of the Respiratory System Bronchial tree – Consists of branched air passages that lead from the trachea to the air sacs Primary bronchi  secondary bronchi  bronchioles  alveolar ducts  alveolar sacs  alveoli ****Respiratory surface is alveoli – exchange of carbon dioxide and oxygen between alveoli & capillaries of circulatory system****

Organs of the Respiratory System Bronchial tree (con’t) Structure of the respiratory tubes As tubes branch the amount of cartilage in the wall decreases and the muscular layer becomes more prominent Elastic fibers in the walls aid the breathing mechanism Epithelial lining changes from pseudostratified & ciliated to cuboidal & simple squamous as tubes decrease in size

Organs of the Respiratory System

Organs of the Respiratory System

Organs of the Respiratory System Lungs Left and right lungs are separated by the mediastinum and are enclosed by the diaphragm & the thoracic cage Visceral pleura is attached to the surface of the lungs; parietal lines the thoracic cavity R. lung – 3 lobes; L. lung – 2 lobes Lobes contain – alveoli, nerves, blood vessel, and lymphatic & connective tissue (no muscle tissue)

Organs of the Respiratory System

Organs of the Respiratory System

Inspiration – air moves into lungs (atm. Pressure = 760 mm Hg) Breathing/Pulmonary Ventiliation – Fig. 14-11 – movement of air into & out of lungs Inspiration – air moves into lungs (atm. Pressure = 760 mm Hg) Phrenic nerve impulses cause diaphragm to contract As dome shaped diaphragm moves downward the size of the thoracic cavity increases External intercostal muscles may contract causing ribs to rise which causes in increase in the size of thoracic cavity As size of thoracic cavity increases pressure within alveoli DECREASES (758 mm Hg) Atm. Pressure which is greater on the outside forces air into respiratory tract Lungs inflate

Expiration – air moves out of lungs Breathing/Pulmonary Ventilation – Fig. 14-11 – movement of air into & out of lungs Expiration – air moves out of lungs Diaphragm & external respiratory muscles relax Elastic tissue of the lungs, thoracic cage and abdominal organs, which were stretched during inspiration suddenly recoil & surface tension causes alveolar walls to collapse Pressure within the alveoli INCREASES (761 mm Hg) causing expiration of air out of lungs

Breathing/Pulmonary Ventilation – Fig Breathing/Pulmonary Ventilation – Fig. 14-11 – movement of air into & out of lungs http://www.youtube.com/watch?v=q6-oyxnkZC0 (Boyles Law and ventilation)

Respiratory or Pulmonary Air Volumes & Capacities – Fig. 14-13 Breathing/Pulmonary Ventilation – Fig. 14-11 – movement of air into & out of lungs Respiratory or Pulmonary Air Volumes & Capacities – Fig. 14-13 Tidal volume – amount of air that normally moves into or out of lungs during quiet breathing (approx. 500 ml) Inspiratory reserve volume – additional air that can be inhaled (approx. 3000 ml) Expiratory reserve volume – additional air that can be exhaled (approx. 1100 ml) Residual volume – amount of air that remains in lungs (approx. 1200 ml)

Respiratory or Pulmonary Air Volumes & Capacities – Fig. 14-13 Breathing/Pulmonary Ventilation – Fig. 14-11 – movement of air into & out of lungs Respiratory or Pulmonary Air Volumes & Capacities – Fig. 14-13 Vital capacity – maximum amount of air a person can exhale after taking the deepest breath possible VC = TV + IRV + ERV Lung Capacity – TLC = VC + RV – varies with age, sex, body size, athlete vs. non athlete Residual air mixes with new air, this prevents concentrations of oxygen and carbon dioxide from fluctuating excessively with each new breath

Control of Breathing – normal breathing is rhythimic & involuntary, although the respiratory muscles can be controlled voluntarily Respiratory Center Located in the brain stem and includes parts of the medulla oblongata & pons Controls both inspiration & expiration & rates of breathing

Factors affecting breathing Control of Breathing Factors affecting breathing Breathing is affected by certain chemicals, the stretching of lung tissues & the persons emotional state Chemosensitive areas are associated with the respiratory center CO2 combines with H2O to form H2CO3 which in turn dissociates into HCO3- & H+ Chemosensitive areas mainly influenced by [H+], this concentration determines acidity of blood Stimulation of these areas causes the breathing rate to increase

Factors affecting breathing Control of Breathing Factors affecting breathing Chemoreceptors in the carotid & aortic bodies Sensitive to low [O2] When [O2] is low  increase breathing rate An inflation reflex is triggered by stretching the lung tissues; this reflex reduces the duration of inspiratory movements & prevents over-inflation of the lungs during forceful breathing

Alveolar Gas Exchange – Internal Respiration Alveoli Tiny sacs clustered at the distal ends of the alveolar ducts Some alveoli have openings into adjacent air sacs that provide alternate pathways for air when passages are obstructed Respiratory Membrane/Surface Consists of the alveolar & capillary walls Gas exchange occurs here Diffusion Gasses diffuse from regions of higher concentration to lower concentration O2 diffuses from alveoli to capillaries; CO2 diffuses from capillaries to lungs

Organs of the Respiratory System

Organs of the Respiratory System

Transport of Gases – blood transports O2 & CO2 – Fig. 14-12 O2 transport Mainly combines with HB (hemoglobin) to produce oxyhemoglobin O2 + Hb  HbO2 HbO relatively unstable & releases O2 in areas where [O2] pressure is low There is an increase in the release of O2 from the blood when CO2 levels increase pH becomes more acidic blood temperature increases

Transport of Gases – blood transports O2 & CO2 – Fig. 14-12 CO2 transport Carried in solution either bound to Hb or as HCO3- Most CO2 transported as HCO3- (approx. 70%) CO2 + Hb  HbNHCOOH (carbamino hemoglobin) (approx. 23%) Some dissolved in plasma (approx. 7%)

Transport of Gases – blood transports O2 & CO2 – Fig. 14-12 Carbon monoxide – CO Combines with Hb more readily than O2 & forms a stable compound Toxic because decreases Hb available for transport of O2 Utilization of O2 – used for cellular respiration C6H12O6 + 6O2  6CO2 + H2O + ATP