Respiratory System Every animal needs a system to take in oxygen from the environment Why is oxygen needed? Oxygen is required for cell respiration Oxygen and nutrients are combined to release energy Remember cell respiration? Reactants: Products: Glucose + O2 CO2 + H2O + Energy

How Does Oxygen Get Into Cells? O2 and CO2 enter and leave the cells (gas exchange) by diffusion Different animals have different systems Some examples: Organism: Gas exchange between: one-celled cell membrane and outside cell earthworm skin and capillaries insects trachea and body cells fish gill filaments and capillaries mammals air sacs (alveoli) and capillaries

Human Respiratory System Our own pathway, in order: Mouth/Nasal Cavity Pharynx Larynx Trachea Bronchi Bronchioles Alveoli (tiny air sacs)

Respiratory System Tissues Mouth/nasal cavity: Air enters the body Nasal hairs and mucus warm and clean the air Pharynx and larynx: Pharynx is the back of your mouth (say aaaaah) Larynx is lower – this is your throat (voice box) Trachea: Air passageway leading to lungs Lined with C-shaped rings of cartilage Bronchi, bronchioles, alveoli: Air pathway into each lung branches down and ends in millions of microscopic air sacs (alveoli) An adult human lung has several hundred million alveoli, each one surrounded by capillaries of your circulatory system

How Air Moves in and Out Inhaling: getting oxygen in Exhaling: getting carbon dioxide out Air is forced into and out of your lungs. But how? When you squeeze a plastic bottle, what does the air do? Which direction does it move? When you let the plastic bottle spring back into shape, what does the air do? Which direction does it move now? This is because of an important law of how gases work: Boyle’s Law

Boyle’s Law Robert Boyle discovered that if: volume decreases, pressure increases volume increases, pressure decreases Pressure and volume are inversely related: If one increases, the other decreases This is called an inverse relationship Gases always move from: areas of higher pressure to areas of lower pressure Boyle’s Law explains how air is forced into and out of your lungs !

1. Diaphragm & rib muscles contract 2. Rib cage expands 3. Volume in lungs increases 4. Pressure in lungs decreases 5. Air pressure outside is greater 6. Air rushes into lungs 1. 2. 3. 4. 5. 6. Can you fill in steps 1- 6 for exhaling?

How Does O2 Get Into the Blood? A i r To heart From heart A i r Alveolus (air sac) O2 CO2 Pulmonary capillary

How Does O2 Get Into the Blood? Blood needs a special chemical to “carry” the oxygen: Hemoglobin oxygen “sticks to” or binds with hemoglobin in red blood cells hemoglobin contains iron which binds with oxygen Can you follow the oxygen? In the lungs: Oxygen diffuses from the air in the alveoli into capillaries Oxygen passes into red blood cells and binds with hemoglobin In the blood, oxygen remains bound to hemoglobin until it reaches your cells At your cells: CO2 diffuses from cells into capillaries Hemoglobin releases oxygen and binds with CO2 Oxygen diffuses from red blood cells into your body cells

Respiratory System Problems Dirt, pollen, dust, and smoke damage the system and interrupt the flow of oxygen to your cells Respiratory System Defenses: White blood cells Surround, consume, and digest bacteria Cannot consume asbestos Cilia Tiny hairs lining trachea Hairs “wave” upward to expel foreign particles Cigarette smoke paralyzes cilia Defense against choking: The epiglottis Flap of tissue that closes trachea when you swallow Makes certain food travels through esophagus instead

Respiratory Disorders Asthma Bronchial tubes become constricted Symptoms: shortness of breath, wheezing, coughing Causes: environmental factors: allergies, stress, certain foods Emphysema Alveoli lose ability to expand and contract when breathing Alveoli stretch and rupture; scar tissue develops Less oxygen to cells + buildup of CO2 Lung cancer Caused by “tars” and other carcinogens in cigarette smoke Cancerous tumors destroy lung tissue Effects of smoking: Short term: carbon monoxide (CO) replaces oxygen in blood Long term: heart disease, emphysema, lung cancer Without smoking, these disorders are a minor problem in society

Review Questions Which term does not belong with the others and why not? gills, alveoli, diaphragm, trachea asthma, respiration, emphysema, lung cancer gills, lungs, hemoglobin lung cancer, asthma, emphysema alveoli, diaphragm, trachea Explain what happens to your diaphragm and ribcage when you inhale and exhale. What are the reactants and products of cell respiration? Use Boyle’s Law to explain inhaling, exhaling, and why the Heimlich Maneuver works. Describe how gas exchange occurs in the lungs. Why is your trachea lined with cartilage? What is the function of your nasal cavity? What is your epiglottis and what is it for? Why do you have cilia inside your trachea? Which respiratory condition can be the result of allergies?