The Respiratory System Accelerated Biology

Function of the Respiratory System The job of the respiratory system is to obtain oxygen and eliminate carbon dioxide CO2 is a waste product of cellular respiration and is toxic to cells Then, the circulatory system transports the oxygen and carbon dioxide throughout the body

Structures of the Respiratory System Nasal cavity – lined with cilia to trap inhaled particles and moisten and warm the air mucus – traps inhaled particles cilia – sweeps mucus up to throat to be swallowed Pharynx – where oral and nasal cavities meet. Passageway for air and food Larynx – voice box

Structures of the Respiratory System Ciliated epithelium of the respiratory system. SEM X5000

Structures of the Respiratory System Epiglottis – flap of cartilage that covers the trachea when swallowing to prevent food and liquids from entering your lungs

Structures of the Respiratory System Trachea – wind pipe with cartilaginous rings Bronchi – two branches of the trachea that lead to each lung

Structures of the Respiratory System Bronchiole – smaller branches of the two bronchi that end in tiny air sacs called alveoli

Structures of the Respiratory System Alveoli – You have 300,000,000 air sacs in your lungs where gas exchange occurs Increase the surface area of your lungs to 42x the surface area of your body Their membranes are one cell thick and are surrounded with capillaries.

Aveoli In the lungs

Structures of the Respiratory System Diaphragm – thin sheet of smooth muscle spanning the rib cage that moves up and down to bring air into and out of the lungs

Breathing Breathing occurs because of air pressure differences between the lungs and the atmosphere Lungs have no muscles, so the work is done by the diaphragm and intercostal muscles Intercostals – muscles between the ribs

Inhalation Gain O2 by inhaling Intercostals and diaphragm contract Diaphragm flattens and pulls downward Rib cage is pushed up and out causing a decrease in the air pressure in the lungs (air pressure in lungs is now lower than atmospheric pressure) Air is sucked into lungs

Exhalation Rid body of CO2 by exhaling Passive - also due to change in lung air pressure Intercostals and diaphragm relax, decreasing the volume in the chest cavity Increases the air pressure in the lungs (higher than atmospheric pressure) Air is forced out

Inhalation and Exhalation

Gas Exchange The exchange of CO2 and O2 in both the body tissues and the lungs. Occurs as a result of diffusion O2 from alveoli diffuses into the blood in the capillaries, in turn CO2 in the blood diffuses into the alveoli Body tissues – CO2 levels high, O2 levels low RBC in lungs – O2 levels high, CO2 levels low

How is breathing regulated? Receptors in the brain and the cardiovascular system continually monitor the levels of O2 and CO2 in the blood As CO2 levels increase, the pH decreases (blood becomes more acidic) causing a person’s breathing rate to increase. Thus, they will expel more CO2 and take in more O2

How is breathing regulated? CO2 combines with H2O to form carbonic acid (H2CO3) Carbonic acid breaks up to form bicarbonate ions (HCO3) and Hydrogen ions (H+) Most CO2 travels to the lungs as bicarbonate ions (HCO3) The H+ ions is what makes the blood acidic, causing an increase in breathing. The Equation: H2O + CO2 H2CO3 HCO3- + H+

Carbon Monoxide poisoning Carbon Monoxide binds more readily to hemoglobin than oxygen and carbon dioxide If present, it will prevent oxygen from being delivered and lead to hypoxia, an inadequate oxygen supply

Asthma Asthma – Chronic condition where the bronchioles of the lungs become inflamed due to sensitivity of stimuli in the air Bronchial walls tighten and extra mucus is produced causing airways to narrow Strenuous exercise and stressful situations can trigger an asthma attack

The effects of smoking Emphysema – Elastic fibers in the lungs are destroyed Begins with the destruction of the alveoli Results in fatigue and breathlessness Smoking causes 90% of emphysema cases

The effects of smoking Lung Cancer – abnormal cell growth One of the leading of causes of death in the world Accounts for 28% of all cancer deaths Smoking is the major cause of lung cancer