Respiration & Gas Exhange

Respiration Two processes: 1. Release of energy from breakdown of food molecules. All living cells use oxygen to release energy. This process produces waste carbon dioxide. 2.The exchange of gases between the atmosphere and body’s cells. We will focus on the exchange of gases.

So what are the functions of the respiratory system? Bring oxygen into the body Remove carbon dioxide (CO2) from the body Clean, moisten and warm air Enable speech

Gas exchange supplies oxygen for cellular respiration and removes CO2 ………………………………………………………………………………………………………………… Gas exchange supplies oxygen for cellular respiration and removes CO2 Gas exchange – uptake of O2 from environment and discharge of CO2 Mitochondria need O2 to produce more ATP, CO2 is the by-product C6H12O6 + 6O2  6CO2 + 6H2O + 36 ATP DIFFUSION

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

Respiratory surfaces and gas exchange Size of organism Habitat Metabolic demands Unicellular organisms Entire surface area for diffusion Simple invertebrates Sponges, cnidarians, flatworms diffusion

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

Mammalian respiration

Organs of the respiratory system Nose and sinuses Q. List the advantages of breathing in from the nose? (page 170 ) 1. Cleans dust and bacteria in the air by hair and mucus, 2. warms and moistens the air 3. Detect harmful chemicals by sensory cells

Organs of the respiratory system Hyoid Bone Epiglottis Thyrohyoid Membrane Cricothyroid Ligament Muscles Cartilage Trachea Thyroid Pharynx – short tube leading to larynx Epiglottis – cartilaginous flap covering opening to larynx (glottis) Larynx – voicebox containing vocal cords

Organs of the respiratory system Trachea – tubes leading into lungs. These branch into primary bronchi then into bronchioles mouth trachea bronchi alveoli

larynx bronchiole sinuses pharynx trachea alveoli bronchial tube

Organs of the respiratory system Bronchioles end in sac like structures called Alveoli Gas exchange occurs between the alveoli and capillaries Primary bronchus Alveoli Terminal bronchiole Bronchiole Tertiary Secondary

Bronchial Tubes

Gas Exchange Capillaries surround the alveoli Gases are exchanged between the thin walls of the alveoli and capillaries

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

How Air Moves in and Out Inhaling: getting air with oxygen in Exhaling: getting air with 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 (external intercostal 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?

Lung ventilation through breathing Negative pressure breathing in reptiles and mammals Rib muscles and diaphragm change lung volume and pressure

Lung volumes Factors Vital capacity Residual volume Tidal volume Smoking, increase due to CO Anxiety, increase due to the effect of adrenaline Drugs, some may cause an increase Environmental factors, increased by high CO2 concentration in the atmosphere Altitude, increased by low O2 conc. In the atmosphere Weight, can increase because fat makes lung ventilation harder (i.e tidal volume falls), Tidal volume Volume of air inhaled and exhaled with each breath Vital capacity Maximum volume inhaled and exhaled during forced breathing Residual volume Air left in alveoli after forced exhalation

Control centers in the brain regulate breathing

Gases diffuse down pressure gradients concentration and pressure drives the movement of gases into and out of blood

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?