The Respiratory System Ms. Cohen Anatomy & Physiology 2011 - 2012

The Basic Functions Organs of respiratory system are designed to: Serve as air distributor Gas exchanger for the body Filters, warms and humidifies air we breathe Accessory organs influence speech, sound, smell

Organs of the respiratory system Upper respiratory tract - Nose, pharynx, larynx Lower respiratory tract - trachea, all segments of bronchial tree, lungs

Respiratory Mucosa Membrane that lines most of the air distribution tubes in the system. Main function is to cleanse, warm and humidify inspired air. Mucous blanket covers lining of tubes. Microscopic cilia move materials along.

The NOSE Air enters thru nostrils/nares Flows into nasal cavities. Moist from mucus and warm from blood flowing underneath. Nerve endings in nasal mucosa smell 4 sinuses drain into nasal cavity When nasal mucosa is inflamed - sinusitis

The Pharynx Often called the “throat” Hallway for digestive and respiratory system 12.5 cm long, 3 sections Nasopharynx - upper Oropharynx - behind mouth Laryngopharynx -lower

Pharynx, continued… Right and left auditory or eustachian tubes open into the nasopharynx; they connect middle ears with pharynx. Permits equalization of air pressure b/t middle and exterior ear. Tonsils, which contribute to lymph system (defense) are embedded in mucous membrane.

Larynx/voice box Located just below pharynx Composed of several pieces of cartilage Largest is “Adams apple” (thyroid cartilage) Vocal cords stretch across larynx Epiglottis (cartilage) trapdoor for larynx

Trachea A.K.A. “windpipe” 11cm long From larynx to bronchi Furnishes part of open passageway thru which air can reach the lungs.

Trachea

THE LUNGS!! Large organ R. lung - L. lung - R - 3 lobes, L - 2 lobes Covered by pleura - thin, slippery membrane covering lungs (visceral pleura) and lines thoracic cavity (parietal pleura)

Bronchi, bronchioles, alveoli Right and left bronchi branch from trachea - Secondary bronchi - Eventually branch into tiny tubes containing smooth muscle only - primary bronchi in each lung, bronchi branch bronchioles

Alveoli Structure Basic tube with many branches ending in millions of extremely tiny, very thin-walled sacs called ALVEOLI that specialize in gas exchange via diffusion.

Why do alveoli work so well? The wall of each alveolus is made up of Capillaries are also made up single cell layer RESPIRATORY MEMBRANE How many alveoli are there? a single layer of cells This thin layer b/t blood and air is less than 1 micron Millions of alveoli which makes enormous SA (100 sq. meters)

Respiration Pulmonary ventilation is the process that moves air into and out of the lungs. Makes possible external respiration- Also makes possible internal respiration, Cellular respiration, the exchange of gases b/t air in the lungs and blood. exchange of gases b/t blood and cells in the body. refers to the actual use of oxygen by cells in the process of metabolism!

Pulmonary Ventilation Two phases: Inspiration - inhalation moves air into lungs and Exhalation - moves air out of lungs. Changes in thoracic cavity result in changes in the air pressure w/i cavity and lungs Air moves from an area where pressure is high to an area where pressure is lower. Respiratory muscles are responsible for the changes in shape of thoracic cavity.

Inspiration Diaphragm contracts Increasing volume of thoracic cavity Decreases pressure Causes air to rush into lungs.

Expiration Diaphragm returns to an upward position Reduces the volume in thoracic cavity Air pressure increases Forces air out of lungs

What about Carbon Dioxide? Most carbon dioxide is carried as bicarbonate ion (HCO3-) in the blood Some combines with hemoglobin to form carbaminohemoglobin As cells remove oxygen from circulating blood, they add the waste product to it Follows rules of diffusion

Air exchange Spirometer is used to measure amount of air exchanged in breathing This amount is referred to as the TIDAL VOLUME (TV) We take in 500ml (pint) of air into our lungs with each inspiration and expiration

Ventilation Terms Vital Capacity(VC) - In normal young adults = 4800ml Inspiratory reserve volume (IRV) - As TV increases, the ERV and IRV decreases. VC = TV+IRV+ERV Residual volume (RV) = Vital Capacity(VC) - In normal young adults = 4800ml Expiratory reserve volume (ERV) - VC largest amount of air that we can breathe out in one expiration ERV amount of air that can be forcibly exhaled after expiring TV IRV amount of air that can be forcibly inspired over and above a normal inspiration RV air that remains in lungs after the most forceful expiration.

Pulmonary Ventilation Volumes

Regulation of Respiration The body makes automatic adjustments in respiration and circulation rates when it needs to Heart beats faster, harder = pumps more blood/min. RBC make more round trips thru body

How is it regulated? Cerebral cortex can influence by modifying the rate at which neurons fire in the insp. & exp. Centers. I.E.holding breath Muscle control - stimulated by nervous impulses originated in respiratory control centers in medulla & pons

Types of Breathing Eupnea - normal respiratory rate Hyperventilation - very rapid respiration Hypoventilation - slow/shallow respiration Dyspnea- labored or difficult breathing associated with hyperventilation Orthopnea - dyspnea that is relieved by moving into an upright position Apnea - when breathing stops

Chronic Obstructive Pulmonary Disease (COPD) Disorders Chronic Bronchitis: Emphysema: Asthma: chronic (ongoing) inflammation of bronchi and bronchioles torn walls of alveoli periodic constriction of bronchioles, often due to inflammation, triggered by stress, heavy exercise, infection, or inhaling allergens

ASTHMA