RESPIRATORY SYSTEM

Respiratory system  Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood.  This exchange process occurs in the alveolar region of the lungs

Respiratory Control  Ventilation occurs under the control of the autonomic nervous system from parts of the brain stem, the medulla oblongata and the pons.  This area of the brain forms the respiration regulatory center, a series of interconnected brain cells within the lower and middle brain stem which coordinate respiratory movements.  This section is especially sensitive during infancy, and the neurons can be destroyed if the infant is dropped and/or shaken violently. The result can be death due to "shaken baby syndrome”

Control of Breathing  Breathing is regulated by the rhythmicity center in the medulla of brain  Medulla stimulates inspiratory muscles (diaphragm & external intercostal muscles) rhytmicity center

Control of Breathing

Human Respiration  Works together with the circulatory system  Exchange of gases between atmosphere, blood, and cells  If respiratory system and/or circulatory system fails, death will occur  Cells need O 2 for work; release CO 2 as a waste product  Accumulation of excess CO 2 is toxic to cells and MUST be removed

Respiratory System  Intakes oxygen  Releases carbon dioxide waste Circulatory system  Transports gases in blood between lungs and cells

Respiratory Structures and Organs

 Nose – made of cartilage and bone and is designed to warm, moisten, and filter air as it comes into the system  Pharynx – (throat) conducts food and air; exchanges air with Eustachian tube to equalize pressure

Respiratory Structures and Organs  Larynx – (voice box) connects the pharynx and the trachea; made of cartilage; contains vocal cords  Epiglottis – flap of tissue that covers trachea; ensures food travels down the esophagus

 Trachea – (windpipe) tubular passage way for air; carries air to the lungs  Bronchi – pair of tubes that branch from trachea and enter lungs; have cartilage plates; lining is ciliated & secretes mucus larynx trachea bronchi bronchioles

Respiratory Structures and Organs  Bronchioles – tiny tubes lacking cartilage and cilia; possess smooth muscle bronchiole smooth muscle

Respiratory Structures and Organs  Alveoli – cup shaped structures at the end of the bronchioles that resemble bunches of grapes; are in direct contact with capillaries (gas exchange);

Alveoli

 Lungs – paired, cone-shaped organs that are surrounded by a pleural membrane, made of elastic tissue, and divided into lobes

Mechanics of Breathing  Inhaling (active process) – Air moves in. Why?? Gases move from an area of high pressure to low pressure During inspiration – diaphragm pulls down and lungs expand When lungs expand, it INCREASES the VOLUME, which DECREASES the PRESSURE inside lungs Lung pressure is lower than outside pressure, so air moves in

Mechanics of Breathing  Exhaling (passive process) – breathing out Diaphragm and muscles relax Volume in lungs and chest cavity decreases, so now pressure inside increases Air moves out because pressure inside is HIGHER than OUTSIDE atmosphere

Respiration  What is respiration? External respiration – exchange of O 2 and CO 2 between respiratory surfaces and the blood (breathing) Internal respiration – exchange of O 2 and CO 2 between the blood and cells Cellular respiration – process by which cells use O 2 to produce ATP

External Respiration  Exchange of O 2 and CO 2 between alveoli and blood  Partial pressure of O 2 higher in alveoli than blood so O 2 diffuses into blood  Partial pressure of CO 2 higher in blood than alveoli, so CO 2 moves into alveoli in opposite direction and gets exhaled out

Internal Respiration  Exchange of O 2 and CO 2 between blood and tissues  Pressure of O 2 higher in blood than tissues so O 2 gets release into tissues.  Pressure of CO 2 higher in tissue than in blood so CO 2 diffused in opposite direction into blood.  CO 2 Is a waste product  O 2 Is used in cellular respiration

Gas Exchange  Earth’s atmosphere is about 78% Nitrogen and about 21% O 2  What happens to the air when we inhale?  300 million alveoli in a healthy lung  Hemoglobin can hold four O 2 molecules GASINHALEDEXHALED O2O %14.6% CO 2.004%4.0% H2OH2O1.25%5.9%

Gas Transport in Blood  Carbon dioxide 70% as bicarbonate ion (HCO 3 - ) dissolved in plasma 23% bound to hemoglobin 7% as CO 2 dissolved in plasma  Oxygen 99% bound to hemoglobin 1% as O 2 dissolved in plasma  Carbon monoxide poisoning occurs because CO binds to hemoglobin more readily than O 2

Lung Defense systems  Airway epithelial cells can secrete a variety of molecules that aid in lung defense. Secretory mmunoglobulins (IgA), collectins (including Surfactant A and D), defensins and other peptides and proteases, reactive oxygen species, and reactive nitrogen species are all generated by airway epithelial cells.  These secretions can act directly as antimicrobials to help keep the airway free of infection. Airway epithelial cells also secrete a variety of chemokines and cytokines that recruit the traditional immune cells and others to site of infections.

Respiratory during pregnancy  The respiratory system lies dormant in the human fetus during pregnancy. At birth, the respiratory system becomes fully functional upon exposure to air, although some lung development and growth continues throughout childhood.  The lungs of pre-term infants may not function well because the lack of surfactant leads to increased surface tension within the alveoli. Thus, many alveoli collapse such that no gas exchange can occur within some or most regions of an infant's lungs, a condition termed respiratory distress syndrome.

Infectious respiratory diseases  Infectious, environmental and other "diseases" (e.g., pneumonia, tuberculosis, asbestosis, particulate pollutants)  Coughing is of major importance, as it is the body's main method to remove dust, mucus, saliva, and other debris from the lungs.

Sleep apnea  is a sleep disorder characterized by abnormal pauses in breathing or instances of abnormally low breathing, during sleep.  Each pause in breathing, called an apnea, can last from a few seconds to minutes, and may occur 5 to 30 times or more an hour

Respiratory System Disorders  Asthma – muscles of bronchioles constrict, drastically reducing ventilation  Emphysema – destruction of alveoli  Tuberculosis – highly contagious bacterial infection  Lung cancer – 90% of lung cancer victims have a history of smoking

Facts about ETS  Smoking causes 20% (or 1 in 5) of all deaths in the United States each year.  In 1988, the U.S. Surgeon General reported that nicotine is just as addictive as heroin and cocaine. A "hit" of nicotine reaches the brain in seven seconds, twice as fast as heroin injected into the vein.  There are over 19 known carcinogens in cigarette smoke.

After quitting smoking  At 20 minutes after quitting: Blood pressure decreases Pulse rate drops Body temperature of hands and feet increases.

After quitting smoking  At 8 hours: Carbon monoxide level in blood drops to normal Oxygen level in blood increases to normal

After quitting smoking  At 24 hours: Chance of a heart attack decreases

After quitting smoking  At 48 hours: nerve endings begin regrow

After quitting smoking  Between 2 weeks and 3 months: Circulation improves Walking becomes easier Lung function increases The worst of nicotine withdrawal symptoms subside within the first month. Following that, the focus shifts to learning how to decipher and reprogram the psychological tugs or urges to smoke that we've all built up over the years.

After quitting smoking  At One Year Smoke-Free: Your excess risk of coronary heart disease is decreased to half that of a smoker after one year.

In class exercise  How is it that cigarette smoke can be linked to an increased incidence of many kinds of cancers?  Explain reason(s) why a person who has never smoked a day in their life can get lung cancer?