By: Jatin "The Bear" Kumar, Morgan "The Crippled" Lander, Ryan "The Executioner" Ma

I. What is the Respiratory System?

The anatomical feature of the respiratory system include the heart, the lungs, and the respiratory muscles. It is the location where 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.

A. Structure:

(Key Terms that may help you later on in your life)
Frontal sinus - The air-filled cavities located between the lamina of the frontal bone; drain into the nose though the Ethmoid sinuses and if there is blockage, this causes inflammation of the frontal sinus.
Sphenoid sinus - A pair of paranasal sinuses located centrally between and the behind the eyes, below the ethymoid sinus.
Nasal cavity - It contains the nasal septum, turbinates, and cilia; turbinates are bones that protrude into the nasal cavity; they increase the surface area filtering dust and dirt particles by the mucous membrane; cilia are also called nose hairs that trap larger dirt particles.
Nasal vestibule - The anterior segment of the nasal cavity, especially that enclosed by the alar cartilage, limited posterosuperiorly by the limen masi and lined with a squamous epithelium.
Oral cavity - The region consisting of the vestibulum oris, the narrow cleft between the lips and cheeks, and the teeth and gums and the cavitas oris propria.
Pharynx - Also called the throat; common passageway for air and food that is five inches long.
Epiglottis - Closes over the opening to the larynx when food is swallowed, preventing food from entering the lungs.
Vocal fold - The sharp-edged fold of mucous membrane overlying and incorporating the vocal ligament and the thyroarytenoid muscle and stretching along either wall of the larynx from the angle between the laminae of the thyroid cartilage to the vocal process of the arytenoid cartilage; air flow causes the vocal folds to vibrate in production of the voice.
Thyroid cartilage - The largest of the cartilages of the larynx. It is formed of two approximately quadrilateral plates joined anteriorly to the prominence so formed constituting the laryngeal prominence.
Cricoid cartilage - The lowermost of the laryngeal cartilages. It is shaped like a signet ring, being expanded into a nearly quadrilateral plate posteriorly. The anterior portion is called the arch.
Trachea - Also known as the windpipe. It filters the air we breathe and branches into the bronchi. The bronchi are two air tubes that branch off of the trachea and carry air directly to the lungs.
Apex - The upper part of the lungs.
Superior lobe - The lobe of the right lung that lies above the oblique and horizontal fissures and includes the apical, posterior, and anterior bronchopulmonary segments. In the left lung, the lobe lies above the oblique fissure and contains the apicoposterior, anterior, superior lingular, and inferior segments.
Horizontal fissure - is a fissure separating the superior lobe from the middle lobe. The left lung has no middle lobe, so there is no horizontal fissure on that lung. The horizontal fissure usually extends from the oblique fissure along the border of the 4th rib.
Oblique fissure - separates the inferior lobe of either lung from the remainder of the lung and it separates the inferior from the superior and middle lobe; in the left lung it separates the inferior and superior lobe, as there is no middle lobe in the left lung.
Middle lobe - The middle lobe, the smallest lobe of the right lung, is wedge-shaped, and includes the lower part of the anterior border and the anterior part of the base of the lung.Very important in the process of respiration.
Diaphragm- a sheet of internal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity (heart, lungs & ribs) from the abdominal cavity and performs an important function in respiration. A diaphragm in anatomy can refer to other flat structures such as the urogenital diaphragm or pelvic diaphragm, but "the diaphragm" generally refers to the thoracic diaphragm.
Capillary beds - a network of capillaries in a tissue or organ.
Connective tissue - Animal tissue that functions mainly to bind and support other tissues, having a sparse population of cells scattered through the extracellular matrix.
Alveolar sacs - This is mainly referred to as an anatomical structure that has the form of a hollow cavity. Found in the lung parenchyma, the pulmonary alveoli are the dead ends of the respiratory tree, which outcrop from either alveolar sacs or alveolar ducts, which are both sites of gas exchange with the blood as well.
Alveolar duct - Alveolar ducts are the tiny end ducts of the branching airways that fill the lungs. Each lung holds approximately 1.5 to 2 million of them. The tubules divide into two or three alveolar sacs at the distal end. They are formed from the confluence openings of several alveoli. Distal terminations of alveolar ducts are atria which then end in alveolar sacs.
Mucous gland - The mucous salivary glands are similar in structure to the buccal and labial glands.They are found especially at the back part behind the vallate papillae, but are also present at the apex and marginal parts. And as most people could decipher the mucus gland does, in fact, secrete mucus, such a big surprise.
Mucosal lining- This is a specialized tissue that lines the area around the cavities that are exposed to the air, and most commonly referred to the nose as snot, boogers, slime, and many other various counterparts, of which I have a tendency to ramble about, but take no note to my garrulous nature and rather consider the content rather than the bombast that is very gratuitous.
Pulmonary vein - This is a large blood vessel that carries blood from the lungs to the left atrium of the heart. In humans there are four pulmonary veins, two from each lung. They carry oxygenated blood, which is unusual since almost all other veins carry deoxygenated blood.
Pulmonary artery - the artery that carries deoxygenated blood from the heart to the lungs. It starts from the right ventricle then branches off into the left and right pulmonary artery that delivers blood to the lungs to be oxygenated.
Alveoli - These are tiny air sacs in the lungs. Oxygen and carbon dioxide are exchanged in the blood, getting rid of the carbon dioxide and giving the oxygen to the red blood cells to be first transfered to the left ventricle then to the muscles and organs.
Atrium - Part of the heart. The right and left atriums both receive blood, but the right atrium receives deoxygenated blood from the body while the left atrium receives oxygenated blood from the lungs.
Superior lobe - There are two superior lobes, the right and left superior lob (lung). It is divided by the oblique fissure.
Lingular division bronchus - This is part of the bronchus that is divided where it becomes to look like a tree, and this is where we begin to see the alveoli.
Carina of trachea - It is a cartilaginous ridge separating the openings of the right and left main bronchi at their junction with the trachea.
Intermediate bronchus - It is the portion of the right and left main bronchus between the upper lobar bronchus and the origin of the middle and lower lobar bronchi.
Main bronchi - Two main bronchi: left and right. They both carry air to the lungs and both branch off into small tubes, which in turn become bronchioles. Important: no gas exchange takes place in this part of the lung. Only air transfer.
Lobar bronchus - It is a bronchus extending from a primary bronchus to a segmental bronchus into one of the lobes of the right or left lung.
Cardiac notch - The main function of the cardiac notch is to allow us to distinguish between the left and right lung. It is a notch in the anterior border of the lung.
Lingula of lung - It is a projection of the upper lobe of the left lung that serves as the homologue. Some sources define the lingula as a distinct lobe
Inferior lobe - It is located under the oblique fissure, and it contains five bronchopulmonary segments: superior, medial basal,anterior basal, lateral basal, and posterior basal.


Figure 1.1 shows the whole outline of the respiratory system.

B. Main Functions:

The main function of gas exchange, in short, is the uptake of molecular oxygen from the environment and the discharge of carbon dioxide to the environment. And here is a further explanation as we dive even deeper into the mechanics of gas exchange:

II. Gas exchange:

Gas exchange is usually referred to as respiratory exchange or respiration and it should not be confused with the energy transformations of cellular respiration. Gas exchange is the uptake of molecular O2 from the environment and the discharge of CO2 to the environment. To understand what the driving forces for the gas exchange, we need to calculate partial pressure, the pressure exerted by a particular gas in a mixture of gases. For example, at sea level, the atmosphere exerts a downward force equal to that of a column of mercury (Hg) 760 mm high. Therefore, atmospheric pressure at sea level is 760 mm Hg. Since the atmosphere is 21% O2 by volume, the partial pressure of O2 is 0.21 x 760, or about 160 mm Hg. This value is called the partial pressure of O2 because it is the portion of atmospheric pressure contributed by O2.

A. Partial Pressure Gradients:

Partial pressure is simply the pressure exerted by a particular gas in a mixture of gases. To understand the driving forces for gas exchange, the partial pressure must be calculated. In order to calculate the partial pressure, both the pressure being exerted and the fraction of the mixture being represented by a particular gas needs to be known. Calculating partial pressure for a gas dissolved in liquid, such as water, can be done after water is exposed to the air. The amount of a gas that dissolves in the water is proportional to its partial pressure in the air and its solubility in water.

B. Respiratory Media:

The conditions for gas exchange vary considerably, depending on whether the respiratory medium, the source of oxygen, is air or water. Compared to water, air is much less dense and less viscous. Gas exchange with water as the respiratory medium is much more demanding. You see water lowers the oxygen content, greater density, and greater vescisity mean that aquatic animals such as fishes and lobsters must expend considerable energy to carry out gas exchange. In the context of these challenges, adaptations have evolved that in general enable aquatic animals to be very efficient in gas exchange.

external image lungs.gif
external image lungs.gif
Figure 1.2 shows the respiratory media in the cells of a human being.

C. Respiratory Surfaces:

Cells that carry out gas exchange have a plasma membrane must be in contact with an aqueous solution. Respiratory surfaces are therefore always moist and tend to be large and thin. The structure of a respiratory surface depends mainly on the size of the animal and whether it lives in water or on land, but it is also influenced by metabolic demands for gas exchange. In simple animals, such as sponges, cnidarians, and flatworms, every cell in the body is close enough to the external environment that gases can diffuse quickly between all cells and the environment. However, the bulk of the body's cells lack immediate access to the environment. The respiratory surface in these animals is a thin, moist epithelium that constitutes a respiratory organ. The skin serves as a respiratory organ in some animals, such as earthworms and some amphibians. Below the skin, a dense network of capillaries facilitates the exchange of gases between the circulatory system and the environment. The respiratory surface must remain moist at all times, and allows earthworms the ability to survive for extended periods in only damp places. The general body surface of most animals lacks sufficient area to exchange gases for the whole organism. The solution is a respiratory organ that is extensively folded or branched. This enlarges the available surface area for gas exchange. These three organs include gills, tracheae, and lungs.

1. Gills in Aquatic Animals:
What are gills?
Gills are out-foldings of the body surface that are suspended in the water. Without considering the distribution of the gills, the gills have a total surface area much greater than that of the rest of the body. Movement of the respiratory medium over the respiratory surface, a process called ventilation, maintains the partial pressure gradients of oxygen and carbon dioxide across the gill that are necessary for gas exchange. This means that the fishes have to usually move their gills through the water or move water over their gills.

external image respiration.jpg
external image respiration.jpg

Figure 1.3 shows a picture of a shark, a shark has to keep moving trough the water in order for it to survive, even when sleeping the shark has to ride a current in order for water to move through the gills, since it can't move its gills like most fishes. The arrangements of capillaries in a fish gill allows for countercurrent exchange, the exchange of a substance or heart between two fluids flowing in opposite directions. In a fish gill, this process maximizes gas exchange efficiency.

Video 1.1 shows the process of respiration.

2. Tracheal Systems in Insects:
Although the most familiar respiratory structure among terrestrial animals is the lung, the most common is actually the tracheal system of insects. (There are so many of them that they can take over the world one day if they mutate enough, but Ryan believes robots will take over first.) The tracheal system is made up of air tubes that branch throughout the body, this system is one variation on the theme of an internal respiratory surface. The largest tubes, called tracheae, open to the outside. The finest branches extend close to the surface of nearly every cell, where gas is exchanged by diffusion across the moist epithelium that lines the tips of the tracheal branches. This means that the branches extend throughout the body helping the insect breathe in various locations inside the network of its body. The tracheal system can also transport oxygen and carbon dioxide without the participation of the animal's open circulatory system. Also in many flying insects, alternating contraction and relaxation of the flight muscles pumps air rapidly through the tracheal system.

external image grasshopper-respiratory-system.jpeg
external image grasshopper-respiratory-system.jpeg
Figure 1.4 shows what a tracheal system is, and in the diagram we can see a grasshopper.

3. Lungs:
Lungs, unlike the tracheal system, do not brach though the entire body. Rather, they are localized respiratory organs. This is also the reason why the lung is not directly in contact with all other parts of the body. The gap must be bridged by the circulatory system, which transports gases between the lungs and the rest of the body. Amphibian lungs are relatively small and lack an extensive surface for exchange. All in all, the different animals in the world and their metabolic rate correlate with the size and complexity of the lung.

external image lung-diagram-pleura.jpg
external image lung-diagram-pleura.jpg
Figure 1.5 shows a major organ in the respiratory system, without which the whole organ would not function, the lung.
a. Mammalian Respiratory Systems: A Closer Look:
The fundamentals into understanding the mammal's lung are: air enters through the nostrils, which is then filtered, warmed, humidified, and sampled by the hairs for odors as it flows through a maze of spaces in the nasal cavity. The nasal cavity then leads to the pharynx, and intersections where the paths for air and food cross. For example, when food is swallowed, the larynx moves upward and tips the epiglottis over the glottis, the opening of the trachea, or windpipe. From the larynx air then passes into the trachea. Cartilage reinforcing walls of both the larynx and the trachea keeps this part of the airway open. The exhaled air then rushes ahed through the vocal cords, which is a pair of elastic bands of muscle in the larynx. This causes the creation of sound for those who did not know.
The trachea then fork into two bronchi, one leading to each lung. Within the lung, the bronchi branch repeatedly and refines itself into finer tubes called the bronchioles. The epithelium lining the major branches of this respiratory tree is covered by cilia and a thin film of mucus. The mucus traps all sorts of bad harmful things, such as dust and pollen. This process where the cilia moves the mucus upward into the pharynx, is called mucus escalator, which plays a critical part in the respiratory factor. Gas exchange occurs in the alveoli, air sacs clustered at the tips of the tiniest bronchioles. They are so small that specialized secretions are required to relieve the surface tension in the fluid that coats their surface. These secretions are called surfactants, they contain a mixture of phospholipids and proteins. Lacking cilia or significant air currents to remove particles from their surface, alveoli are highly susceptible to contamination. And from this the white blood cells patrol the alveoli to engulf the foreign particles.

III. Breathing Ventilates the Lungs:

The process that vetilates lungs is breathing, the alternating inhibition and exhalation of air. A variety of mechanism for moving air in and out of lungs have evolved, as we will se by considering breathing in amphibians, mammals and birds.

A. Amphibian Breathing:

Amphibians are very primitive when it comes to breathing, since amphibians have lived in water for first parts of thier life and now they are on land. They need water on thier bodies and other areas to survive. An exeption is the toad which spends most of its life on land. An amphibian such as a frog ventilates its lungs by positive pressure breathing, this means that the organism inflates its lungs with forced airflow. There are three stages to the amphibian breathing process:
1. During the first stage of inhilation, muscles lower the floor of an amphibian's oral cavity, drawing air into its nostrils.
2. Next with the nostrils and mouth closed , the floor of the oral cavity rises, forcing air down the trachea.
3. Then during exhalation, air is forced back out by the elastic recoil of the lungs and by compression of the muscular body wall.

external image Lowering_of_lower_Jaw_Closing_of_external_nares_and_rising_of_lower_jaw.gif
external image Lowering_of_lower_Jaw_Closing_of_external_nares_and_rising_of_lower_jaw.gif
Figure 1.6 shows an amphibian's breathing structure, which is very different from those of mammals and birds

external image Gamabunta.jpg
external image Gamabunta.jpg

Figure 1.6a shows another type of amphibian away from the norm, the toad, which has other means of breathing, p.s smoking is bad for health.

However this process can be disrupted when they engage in courtship rituals or aggressive behavior, and this is when air is taken in several times before being exhaled. A similar process that applies in birds and mammals called exercise.

B. Mammal Breathing:

Unlike amphibians, mammals employ negative pressure breathing, pulling rather than pushing the air into their lungs. Unsing this muscle contraction cavity, mammals lower their air pressure in thier lungs and the outside of the body. During exhalation, the muscles controlling the thoracic cavity relax, and then the volume of the cavity is reduced. When someone expands the thoracic cavity during exhalation it involves the animal's rib muscles and the diaphragm. Inside the thoracic cavity, a double membrane surrounds the lungs. The inner layer of this membrane adheres to the outside of the lungs, and the outer layer adheres to the wall of the thoracic cavity. A thin space filled with fluid separates the two layers. Surface tension in the fluid causes the two layers to stick together like the to plates of glass separated by a film of water.
However this all changes during exercise when other muscles of the neck, back, and chest increase the volume of the thoracic cavity by raising the rib cage. In kangaroos and other species, locomotion causes rhythmic movement of organs in the abdomen, including the stomach and liver, this results in a piston-like pumping motion that pushes and pulls on the diaphragm, further increasing the volume of the air moved in and out of the lungs.
The volume of the air inhaled and exhaled is called the tidal volume, this averages about 500 mL in resting humans. The tidal volume during the maximal inhalation and exhalation is the vital capacity, which is about 3.4 L and 4.8 L for college-age women and men. This indicates that women and men in college, have way too much exercise and stress.
The air that remains after forced exhalation is called residual volume. When we get older our lungs lose quite a bit of their resiliency, causing residual volume increase at the expense of the vital capacity. Because lungs in mammals do not completely empty with each breath, and because inhalation occurs through the same airways as exhalation, each inhalation mixes fresh air with oxygen depleted residual air.

external image Respiratory-System.jpg
external image Respiratory-System.jpg
Figure 1.7 shows the respiratory system of a human being, a mammal, whose breathing is more efficient than an amphibian but less than a bird.

C. Bird Breathing:

Respiration and ventilation is more efficient and more complicated in birds than in mammals. Try this: when birds breathe, they pass air over the gas exchange surface only in one direction. Also, incoming, fresh air does not mix with the air that has already carried out gas exchange. To bring fresh air to their lungs, birds use eight or nine air sacs situated on either side of the lungs.
Because the air in the bird's lungs is renewed with every exhalation, the maximum Po2 in the lungs is higher in birds than in mammals. This is one reason birds function better than mammals in the higher altitudes. For example, when we humans climb up to mount everest we are usually gasping for air, however the same elevation even higher in fact, bar-headed geese fly over easily during their migration season.

external image dino_bird_h.jpg
external image dino_bird_h.jpg
Figure 1.8 shows a picture of how birds and dinosaurs used to breathe and the many similarities they shared. Birds are the most efficient breathers on the planet.

D. Control of Breathing in Humans:

Breathing by a basic fact is regulated by involuntary mechanisms, this means that humans and other mammals have no idea that they are breathing. For example, when I am typing this sentence, my breathing is regulated involuntary. However, as soon as I think of breathing, the involuntary switch is turned off and transferred to manual. You try this, while reading this sentence think about breathing in general and then think about its regulation. As soon as you think about regulating breathing, you learn that you are not being controlled by the involuntary mechanism, rather it is switched to the manual control. To give a further example, when you drive in a long highway, people usually switch to cruise control, and coast the highway. However when you brake, the cruise control turns off and it is switched to manual. So what controls the involuntary mechanism are called breathing control centers, and they are located in two brain regions, the medulla oblongata and the pons, control circuits in the medulla oblongata establish the breathing rhythm. And what about the tempo? The tempo is regulated in the pons. When you breathe deeply, a negative-feedback mechanism prevents the lungs from overextending. In regulating breathing, the medulla uses the pH of the surrounding tissue fluid as an indicator of blood carbon dioxide. The reason that pH can be used in this way is that blood carbon dioxide is the main determinant of the pH of the cerebrospinal fluid.
However, the breathing process can be disturbed during exercise and this lowers the pH be increasing the concentration of carbon dioxide in the blood. In response, by the medulla's control circuits increase the depth and rate of breathing. The oxygen concentration in the blood usually has a little effect in the breathing control centers. But when the oxygen drops very low, oxygen sensors in the aorta and the carotid arteries in the neck send signals to the breathing control centers, which respond by increasing the breathing rate.

external image respiratorydetail.gif
external image respiratorydetail.gif
Figure 1.9 illustrates the breathing control mechanisms in that of humans, and how humans are not aware of breathing, and how it is regulated form the sub-conscious of the mind.

IV. Adaptations for Gas Exchange:

The high metabolic demands of many animals necessitate the exchange or large quantities of oxygen and carbon dioxide.

A. Coordination of Circulation and Gas Exchange:

The partial pressures of oxygen and carbon dioxide in the blood can vary at different points. Blood arriving at the lungs through the pulmonary arteries has a lower PO2 and a higher PCO2 than the air in the avleoli. As blood enters the alveolar capillaries, carbon dioxide diffuses from the blood to the air in the alveoli, while the oxygen in the air dissolves in the fluid that coats the alveolar epithelium and diffuses into the blood. By the time the blood leaves the lungs in the pulmonary veins, the PO2 has been raised, while the PCO2 has been lowered. After returning to the heart, this blood is pumped through the systemic circuit.
In the tissue capillaries, gradients of partial pressure favor the diffusion of oxygen out of the blood while carbon dioxide goes into the blood. These gradients exist because cellular respiration in the mitochondria of cells near each capillary removes the oxygen and adds in carbon dioxide to the surrounding interstitial fluid. After the blood unloads oxygen and uploads carbon dioxide, the blood the returns to the heart and pumped to the lungs again.

B. Respiratory Pigments:

The low solubility of oxygen in water and blood creates a problem for animals that rely in the circulatory system to deliver oxygen. Animals transport most of their oxygen bound to certain proteins called respiratory pigments, which circulate the blood and are contained with specialized cells. The pigments increase the amount of oxygen that can be carried in the circulatory fluid. A variety of respiratory pigments have evolved among the animal taxa. These molecules have a distinctive color and consist of a protein bound to a metal. The respiratory pigment of almost all vertebrates (contained in the erythrocytes) and many invertebrates is hemoglobin.

1. Hemoglobin:
Vertebrate hemoglobin consists of four subunits, called polypeptide chains.


Figure 2.1 is a picture of hemoglobin, a very important molecule in the respiratory system.
Each one consists of a co-factor called a heme group that has an iron atom at its center. Each iron atom binds one molecule of oxygen. Like all respiratory pigments, hemoglobin binds oxygen reversibly, loading oxygen in the lungs or gills and unloading it in other parts of the body. This process depends on the cooperativity between the hemoglobin subunits. When oxygen binds to one subunit, the others change shape slightly, increasing their affinity for oxygen. When four oxygen molecules are bound and one subunit unloads its oxygen, the other three subunits unload, as an associated shape change lowers their affinity for oxygen. Cooperativity in oxygen binding and release in evident is the dissociation curve for hemoglobin. A slight change in PO2 can cause hemoglobin to load or unload a substantial amount of oxygen. When cells in particular locations start working harder, PO2 dips in their vicinity as the oxygen is consumed in cellular respiration. Because of the effect of subunit cooperativity, a slight drop in Po2 causes a relatively large increase in the amount of oxygen the blood unloads. The production of carbon dioxide during cellular respiration promotes the unloading of oxygen by hemoglobin in active tissues. Carbon dioxide reacts with water, forming carbonic acid, which helps lower the pH of its surroundings. Low pH decreases the affinity of hemoglobin for oxygen, an effect called the Bohr shift. Where carbon dioxide production is greater, hemoglobin releases more oxygen, which can later be used to support more cellular respiration.

2. Carbon Dioxide Transport:
Hemoglobin also helps transport carbon dioxide and assists in preventing harmful changes in pH. Only about 7% of the carbon dioxide released by respiring cells is transported in solution in blood plasma. Another 23% binds to the amino acids of the hemoglobin polypeptide chains, and about 70% is transported in the blood in the form of bicarbonate ions. Carbon dioxide from respiring cells diffuses into the blood plasma and then into erythrocytes. When blood flows through the lungs, the relative partial pressures of carbon dioxide favor the diffusion of carbon dioxide out of the blood. As carbon dioxide diffuses into alveoli, the amount of carbon dioxide in the blood decreases. This decrease shifts the chemical equilibrium in favor of the conversion of HCO3- to carbon dioxide, enabling further net diffusion of carbon dioxide into alveoli.

C. Elite Animal Athletes:

For some animals, such as long-distance runners or migrators, the oxygen demands of thier daily activities would overwhelm the capacity of a typical respiration system. For example two types of animals are in need of high demand of specialized respiratory system: endurance runners mammals, and diving mammals.

1. The Ultimate Endurance Runner:
How would it feel to sprint a mile, but not get tired, crazy right but not for these special animals. Pronghorns and antelope-like animals are native to the grassland of the north american landscape, and they are among the fastest animals to live on this land. Pronghorns in fact are second to the cheetah, running at over 65 mph over long distances. So just how do these animals do it? To answer this question, researchers Stan Lindstedt and his colleagues at the University of Wyoming and University of Bern, conducted an experiment. The researchers exercised pronghorns on a treadmill to estimate their maximum rate of oxygen consumption. The results: the pronghorns consumed three times the oxygen for an average animal of their size, normally as animals increase in size, their rate of oxygen consumption per gram of body mass declines. One gram of shrew tissue, for example, consumes as mush oxygen in a day as a gram of elephant tissue consumes in an entire month. But the rate of oxygen consumption per gram of tissue by a pronghorn turned out to be as high as that of a 10-g mouse. But what makes these pronghorns able to consume so much oxygen? Natural selection, the answer to most of the questions of life, since pronghorns run almost exclusively, their rate of oxygen consumption is higher than normal and the body just adapted to it.

Video 1.2 shows a pronghorn running

Cheetah Running
Antelope Running
Figures 2.2 (top) and 2.3 (bottom) are two animals and their unique adaptations that help play an important role in the survival of these beasts.
2. Diving Mammals:
Have you seen the depths of the ocean, without any machines, these animals have. Animals like these are special, they cary greatly in their ability to temporarily inhabit environments in which there is no access to their normal respiratory medium, what does that mean? In english: when an air-breather swims underwater. We humans, cannot hold our breathe longer than 2 to 3 minutes or swim deeper than 20 m, even the most professional of a divers. However the Weddell seal of the Antarctic routinely plunges 200-500m and remains there for about 20 minutes, and sometimes even an hour. Sea-turtles make the Weddell seal look like a sissy, they can dive up to 800m and more! Elephant seals breaks all record and can dive up to 1,500m underwater, almost a mile, and stay submerged for about 2 hours. So what the heck helps these extreme divers to stay that long underwater? The ability to store large amounts of oxygen. Compared with humans the Weddell seal can store about twice as much oxygen per kilogram of body mass. About 36% of our total oxygen is in our lungs, and 51% is on our blood, but in the case of the Weddell seal, it holds a merely 5% of its oxygen in its small lungs, and it stockpiles 70% of the oxygen in its bloodstream.Diving mammals also have a high concentration of an oxygen-storing protein called myoglobin in thier muscles. The Weddell seal can store about 25% of its oxygen in the muscle, compared with the humans who can only store about 13%. Diving mammals not only have a storing mechanism but also a mechanism to conserve the amount of oxygen that is spent. For example the diving mammals heart rate and oxygen consumption decrease when they are diving. And the regulatory mechanisms route most of the blood to the brain, spinal cord, eyes, adrenal glands, and in pregnant seals, the placenta. These special mammals have great adaptations that help to configure thier response to the environmental challenges over the short term by psychological adjustments and over a long term as a result by natural selection.

Video 1.3 shows animals diving

Sperm Whale Diving

Elephant Seal
Weddel Seal
Figures 2.4 (top), 2.5(middle), and 2.6(bottom) all are great underwater animals that are able to dive into the depths of the sea.

Injurious Behavior to the Respiratory System

There are many contributors to the failure of the respiratory system, but one sticks out the most among all these things: smoking, this act can lead to numerous health issues. Lung cancer, Chronic Obstructive Pulmonary Disease (COPD), and many Cardiovascular Diseases. Smoking is often called the slow killer, because of the many diseases that it can cause. Cigarettes, Cigars, and other smoking equipment, all no matter what they say can cause harm to your health. So don't forget if someone offers you a cigarette, slap them and show them this video. And if you ever get the temptation to smoke, call (510)-585-8653, I will come down to wherever you are and slap you back to your senses.

Video 1.4 Shows the harmful effects of smoking
nous savons tout


google translate it! :)

yes we do:)

Secret Easter eggs for those who actually read everything or just scrolled all the way down, wait are the even reading this, whatever, I'm typing!.

Warning: watching these videos could actually teach you something.

walk down memory lane

its all coming back

Well you made, it, or you scrolled all the way down to see this, either way, this is the end. so goodbye, au revoir,adiós,अलविदा, and 再见. But remember keep breathing, oh that's right you don't know that you are breathing, but after reading this sentence you realize you're breathing and are now struggling reading and breathing voluntarily all at the same time. Ha ha take that, so long and:
In case we don't see you, good afternoon, good evening and good night.
-Truman Burbank