Unit 3: The Respiratory System (Lesson 10)

Oxygen (O2) --> Atmosphere (Example)

1. Breathing allows oxygen from the outside to enter the lungs 2. External respiration allows the oxygen to go across the respiratory surface between alveoli and into the blood 3. Internal respiration occurs when the oxygen molecule diffuses across the cell membrane into the cell

The Respiratory System Functions (4)

1. Gas Exchange 2. Capillaries and Hemoglobin 3. Process of Diffusion 4. Breathing Process 5. Breathing Rate

Respiratory Structures within the Thoracic Cavity (4)

1. Lungs 2. Bronchi and Bronchioles 3. Alveoli 4. Diaphragm and Pleura

Respiratory Structures above the Thoracic Cavity (4)

1. Nasal and Oral Cavity 2. Pharynx 3. Larynx 4. Trachea

Breathing Process (4)

A cycle of repetition of inhalation and exhalation (aka- inspiration/expiration) > Air moves in and out of the lungs because of changes of pressure within the thorax, due to action of the diaphragm 1. Inhalation 2. Exhalation 3. Pressure 4. Diaphragm

Hypoxia

A low level of O2 delivered to the cells of the body > Immediate responses to these low levels of O2 include rapid and deeper breathing as well as increased heart rate > Other body responses to this stress, called chronic responses or acclimatization, take longer to develop

Effects of Exercise

A person's vital capacity is greatly affected by their daily activities > Smoking or inactivity decrease the vital capacity by reducing the ability to exchange O2 for CO2 > Regular exercise increases the body's need for O2 and leads to numerous and varied physiological changes that are beneficial from a health standpoint 1. Improved cardio-respiratory function (1) 2. Improved skeletal muscle function 3. Higher bone density 4. Higher levels of high-density lipoprotein cholesterol (the "good" cholesterol) 5. Lower blood pressure 6. Decreased insulin and improved glucose tolerance 7. Enhanced performance at physical activities 8. Many psychological benefits -- In general, regular exercise does not substantially change measures of pulmonary function such as total lung capacity and vital capacity > One of the biggest differences between and athlete and a non-athletes concerns the hearts ability to pump blood and consequently deliver oxygen to working muscles

Breathing Rate

A respiratory control centre in the *medulla oblongata*, at the base of your brain, controls your breathing > This centre sends ongoing signals down your spine, to the nerves of the muscles involved in breathing > Muscular contraction and relaxation controls the rate of expansion and contraction of the lungs > These muscles are stimulated by nerves that carry messages from the medulla 1. Breathing Controls and Malfunctions 2. Monitoring O2, CO2, and Other Substances 3. Resuscitation

Trachea (1)

A tube approximately 12 cm's in length and 2.5 cm's wide > It extends downward from the base of the *larynx* > It lies partly in the neck and partly in the chest cavity > The walls of the trachea are strengthened by stiff rings of cartilage, which keep it open so air can flow through on its way to the lungs > This structure is also lined with *cilia*, which sweep fluids and foreign particles out of the airway so they stay out of the lungs 1. Cilia

Eructation

Air collected in the esophagus and removed by burping

Nasal Cavity (Nostril, Cilia, and Epithelial Lining)

Air enters through the nostrils, where it is warmed and cleaned by small hairs that act like filters to remove dust and particles > As air passes through the nasal cavity, the *cilia* (tiny hair-like projections) on the nasals cavity's *epithelial lining* further filter and moisten the air

Larynx

Also known as the voice box, is the uppermost part of the air passage > This short tube contains a pair of muscles called vocal cords, one on each side of the tube, which vibrate to make sounds, enabling humans to speak and sing > This structure goes directly into the trachea or windpipe

Bronchi and Bronchioles

At the bottom end of the trachea it divides into left and right air tubes which connect to the lungs > These branch from bronchi into small bronchi, into even smaller tubes called bronchioles (these then divide and then subdivide --> Bronchioles are as thin as a strand of hair, end in tiny air sacs called alveoli (which is where the exchange of oxygen (O2) and CO2 takes place) * The network of bronchi, bronchioles, and alveoli within the lungs is known as the bronchial tree Note: They also serve a cleaning function: with ciliated cells secreting mucus (sends the particles to the mouth to be swallowed - 946mL on avg. estimated per/day)

Gas Exchange of O2 & CO2

CO2 diffuses from the red blood cells, through the capillary walls, into the alveoli and then leaves the alveoli through the nose and mouth > O2 diffuses rom the alveoli into the capillaries, and then into the red blood cells

Unequal Distribution in Diffusion

Diffusion requires an unequal distribution of gas molecules > The concentration of O2 in the alveoli must be kept at a higher level than in the blood > The concentration of CO2 in the alveoli must be kept at a lower level that in the blood Note: This is accomplished by continuously bringing fresh air (with lots of O2 and little CO2) into the lungs and the alveoli through the breathing process

Exhalation

During this time, air is pushed out of the lungs, and the thoracic cavity decreases in size

Inhalation

During this time, the thoracic cavity enlarges, and the lungs fill with air

Process of Diffusion (2)

Each alveolus is lined with a thin layer of tissue and fluid that is essential for the diffusion of O2 and CO2 * This is because a gas must dissolve in a liquid in order to enter or leave a cell * > In the tiny capillaries, oxygen is freed from hemoglobin and moves into the cells > CO2 is produced during cellular respiration and diffuses out of these cells into the capillaries; most of it is then dissolved in the plasma of the blood > Blood rich in CO2 then returns to the heart via the veins and from the heart, this blood is pumped to the lungs, where CO2 passes into the alveoli to be exhaled 1. Diffusion 2. Simple Diffusion

Alveoli (3)

Each bronchiole ends in a tiny air chamber that looks like a bunch of grapes, composed of many cup-shaped cavities known as alveoli > Each individual cavity is known as an alveolus and the walls of the alveoli, which are only about one cell thick, are the respiratory surface > They are thin and moist, and are surrounded by capillaries (tiny blood vessels) 1. Gas Exchange of Oxygen & CO2 2. Lung Capacity and Surface Area 3. Smoking Effects

Tidal Capacity

The amount of air your lungs can hold during normal breathing --> The amount of air moved in and out of the body in one breath > This amount of supplies enough O2 for a person who is resting > The amount of air that enters the lungs during normal inhalation at rest is known as *Tidal Volume (TV)* --> The same amount leaves the lungs during exhalation * Average tidal volume is 500mL

Pressure

Gases (O2 and CO2) move from areas of high pressure to areas of low pressure > When internal pressure of the thoracic cavity is less than atmospheric pressure outside of the mouth, gas is drawn inwards in inhalation > The opposite causes gas to move outwards, resulting in exhalation

Stretch Receptors

In the lungs and the chest wall monitor the amount of of stretch in these organs > If the lungs become over-inflated (stretch too much), they signal the respiratory centre to exhale and inhibit inspiration * This mechanism prevents damage to the lungs that would be caused by over-inflation

Lung Capacity and Surface Area

Its estimated that there are150 million alveoli in each lung, with a total surface area of about 70m2 > The gas exchange occurring would not be nearly as large if the lungs were hollow > The inner walls of the alveoli are covered in a lipid-based material: surfactant - helps stabilize the alveoli, preventing them from collapsing > The absence of surfactant would cause the alveoli to behave similar to a plastic bag that is wet on the inside (working at little capacity)

Lung Capacity and Respiratory Volumes

Lung capacity is the amount of space available in the lungs to store air -- Respiratory volumes are the actual amounts of air inhaled, stored, and exhaled from the lungs at any given time -- Both measurements are expressed in millilitres (mL), although they can be expressed in litres (L) or cubic centimetres (CM3) Note: 1 CM3 = 1mL * A Spirometer is a medical device used to measure respiratory volume > Lung capacities different with age, sex, body frame, and aerobic fitness > Measuring your lung capacity can help you determine how much stamina you have available for daily activities or sports > Your lung capacity may be affected by certain disorders: asthma/emphysema > Cigarette smoking will give you noticeable signs of emphysema after only 3 years -- Measuring Lung Capacity: 1. Tidal Capacity (TC) 2. Reserve Volumes (RV) 3. Vital Capacity (VC) 4. Residual Capacity (RC) 5. Total Lung Capacity (TLC) 6. Anatomical Dead Space Air

Air Pollution (3)

Many of us breathe dirty urban air laden with particulates, carbon monoxide, and other substances that are damaging to the respiratory system > Our lungs have a variety of defence mechanisms to help protect themselves 1. Filtration 2. Bronchial Constriction 3. Macrophages

Improved Cardio-Respiratory Function

Means that the body is able to perform exercise much more efficiently > Exercises to improve this function include: swimming, or middle-long distance running, whereby your heart rate is increased consistently but not intensively for long periods of time > This means respiration is more laboured than usual, and the lungs are forced to expand in order to cope with the increased workload to ensure your muscles receives oxygen more quickly > These exercises increase vital capacity as well

Capillaries and Hemoglobin

Note: Thousands of capillaries line the lungs > Their function is to pick up the incoming O2 > Red blood cells contain a protein called *hemoglobin* which has binding sites for O2 and CO2 > As O2 enters the bloodstream, CO2 leaves, exiting the alveoli

Cellular Respiration

Occurs at the cellular level in the cytoplasm and mitochondria, and it needs to occur in every cell > This is the process of oxidizing food molecules, like glucose, into CO2 and water > The energy released is captured in the form of adenosine-5'-triphosphate (ATP) for use by all the energy-consuming activities of the cell > Support for this process resides in the digestive system while it supplies glucose, and the respiratory system supplies O2 an the ability to remove CO2

Bronchial Constriction

One of the most rapid defences against dirty air > The bronchial tubes become narrower, and inhaled particles are more likely to land on the sticky mucous lining as a result of this constriction; however, less air can pass through the lungs, decreasing the amount of O2 being supplied to the body's cells > Chain-smokers remain in a constant state of chronic bronchial constriction

The Human Body at Higher Elevations (2)

Our bodies are adapted to perform at sea level, as you climb higher, the proportion of each gas in the air stays the same but because of lower pressure, the gas expands - making the air "thinner" > Therefore, each breath at high altitudes actually brings in less O2 than at sea level > A low level of O2 delivered to the cells of the body produces a condition called hypoxia(1) 2. Acclimatization

Acclimatization

People living at high altitudes acclimatize in several ways to help them function at high altitudes 1. Increased production of red blood cells (which can take up to two months to mature) 2. Improved circulation to body tissues (20-30% of the body's capillary system is normally not used, but at high altitudes all the capillaries are used to deliver O2 to tissues 3. Increased pulmonary blood pressure 4. Increased mitochondrial density 5. Increased muscle myoglobin

Disorders

People that smoke are highly susceptible to emphysema > There is also a strong link between cigarette smoking and lung cancer > Related Cancers: lung, mouth, lip, tongue, throat, larynx, pancreas, esophagus, and pharynx - have all seen marked increases over the 20th century

Anatomical Dead Space Air

Some air remains behind in various parts of the respiratory tract > The air in the trachea, bronchi, and bronchioles (where no diffusion occurs) is called anatomical dead space air, and always consists of the last bit of air exhaled from the previous exhalation > When 500mL of air is inhaled, 150mL occupies anatomical dead space and does not reach the alveoli - only 350mL of the inhaled air is available for gas exchange and 150mL of the air is depleted O2 (stale)

Monitoring O2, CO2, and Other Substances (2)

Specialized nerve cells within the aorta and carotid arteries of the heart called peripheral chemoreceptors(PC) monitor the O2 concentration of the blood/CO2 concentration and provide feedback to the control centre > O2 c. Decreases = the PC tell the respiratory centre to increase the rate and depth of breathing > CO2 c. Increases = the PC signal the respiratory centre to increase the rate and depth of breathing > For both situations, the rate of breathing returns the O2 c. and the CO2 c. back to normal 1. Stretch Receptors 2. Never Cells

Trachea (Bronci)

The air then passes down the *trachea*, through the two tubes called *bronchi*, each of which is attached to a lung, then into the lungs

Mouth (Larynx/Voice-Box)

The air then passes through the back of the mouth, crossing the path of food as it enters the *larynx* (or voice-box)

Resuscitation

The air we breath is approximately 21% O2 and 0.04% CO2 > O2 is used to produce energy and CO2 is a waste produce of producing energy; therefore, the air exhaled will contain less O2 and more CO2 than breathed in > However, 17% O2 and 3% CO2 is exhaled, which is more than enough for mouth-to-mouth resuscitation *Note: Carbon dioxide levels only become toxic above 5%* > On avg. the human takes one breath every 5 seconds

Macrophages (Specialized WB Cells)

The alveoli are not equipped with mucus or ciliated cells and foreign particles that make their way unto the alveoli are engulfed and "eaten" by specialized white blood cells > If there are too many foreign particles present because of air pollution, there may be a build up of these specialized WB cells > These can accumulate in the lymph tissue of the lungs, causing inflammation and illness

Reserve Volumes

The amount of extra air (beyond tidal volume) inhaled during a deep breath is known as inspiratory reserve volume (IRV) --> This can be as high as 3000mL > This expiratory reserve volume (ERV) is the amount of extra air (beyond tidal volume) exhaled during a forceful breath out

Residual Capacity

The amount of room left in the lungs after a deep exhalation > The actual amount of air left in the lungs following a maximal exhalation is known as the *residual volume (RV)*

Lungs

The chest/thoracic cavity is an airtight system that houses the bronchi, bronchioles, lungs, heart, and other structures > The top and sides of the thorax are formed by the ribs and attached muscles, and the bottom is formed by the diaphragm > The chest walls and ribs form a protective cage around the lungs and other contents > The lungs are located on either side of the heart in the thoracic cavity UPPER: near the collarbone (or clavicle), is called the *apex* LOWER: the broad lower part is called the base (the base of ea. lung rests on the diaphragm) Note: Lung tissue is porous and spongy due to the tremendous amount of air sacs that it contains * The right lung is larger and broader than the left due to the shape and location of the heart --> It is also shorter due to the diaphragms upward displacement to accommodate the liver RIGHT: has three lobs LEFT: has two lobes

Hiccups

The diaphragm almost always works perfectly, unless it becomes irritated > If so, it will pull down in a jerky way, which makes you suck air into your throat suddenly > As the air rushes in, it hits your voice box and you are left with hiccup

Simple Diffusion (1)

The exchange of gases (O2 and CO2) between the alveoli and the blood > O2 diffusing from the alveoli into the blood > CO2 diffusing from the blood into the alveoli 1. Unequal Distribution in Diffusion

External Respiration

The exchange of gases across the respiratory surface, between air sacs called alveoli and the blood > Respiratory Surface: this is where O2 diffuses into the organism and CO2 diffuses out of the organism > The surface most be moist in order for diffusion to occur

Internal Respiration

The exchange of gases between the blood and the individual cell in the tissue > O2 diffuses out of the blood and CO2 diffuses into the blood > This exchange makes it possible for cellular respiration to occur

Filtration

The hairs inside the nostrils (cilia) and the ciliated mucous lining in the nose and pharynx act as filters that trap foreign particles in inhaled air, preventing them from reaching the lungs

Thoracic Cavity (Lungs, Ribs, Diaphragm, Abdominal Cavity)

The human lungs are located in the *thoracic cavity* (chest cavity) > The thoracic cavity is bounded on its side by the ribs and inter-costal muscles, and on the bottom by a thick layer of muscle (*diaphragm*), which separates the thoracic cavity and the *abdominal cavity*

Diaphragm and Pleura

The lungs elastic tissues that allow them to inflate and deflate without losing shape > Lungs are connected to the diaphragm and to the walls of the thorax by the pleura 1. Parietal Pleura - lines the chest wall 2. Visceral Pleura - on the surface of the lungs --> Between the two pleural membranes is a fluid that prevents friction and keeps the two membranes together during breathing * The lungs cannot inflate/deflate on their own and requires the use of the diaphragm, which is the major muscle for respiration* > It is a large dome-shaped muscle located below the lungs that contracts rhythmically and continually, most of the time involuntary INHALATION: it contacts and flattens, and the chest cavity enlarges (this creates a vacuum, which pulls air into the lungs EXHALATION: it relaxes and returns to its domelike shape, and air is forced out of the lungs

Tar

The lungs of a smoker usually have dark spots corresponding to the areas containing tar and nicotine > The tar can be particularly damaging, as prolonged exposure can lead to the narrowing of the bronchioles and destruction of the lungs protection and filter system > The cilia of the lungs get coated with tar, so they cannot clean themselves and the smoker develops smoker's hack - a persistent cough that is a reaction to dirty lungs > Quitting smoking can and will reverse this effect; the cilia will recover, and eventually removing all traces of all smoke particles from them --> That process can work as long as the smoker hasn't already developed chronic obstructive pulmonary disorder

Gas Exchange

The main function of the respiratory system refers to the process of oxygen (O2) and carbon dioxide (CO2) moving between the lungs and blood > Efficient exchanges of these gases can only occur if the alveoli are flushed regularly with fresh air

Mount Everest

The maximum amount of O2 that can be extracted form the air and delivered to the cells is only 30-40% of sea level readings; therefore, doing work at high altitudes is indeed much more difficult that at sea level, even with acclimatization

Nasal and Oral Cavity

The nose serves three purposes: 1. warming, 2. filters, and 3. moistens the air before it reaches the lungs > This does not happen if you breathe through your mouth but is a large portal for air right into the trachea > Nasal Cavity; aka - *nasopharynx* is lined with mucous membranes, which contain many folds to provide a large surface area --> This facilitates temperature and moisture control --> Cells in the nasal c. secrete a sticky fluid called mucus that traps dust, particulate matter (such as pollen), bacteria, and other particles (mucus also helps moisten the air) > Under the mucous membrane, there are a large number of capillaries --> The blood within these capillaries helps warm the air as it passes through the nose (runny nose = producing more fluid to warm and moisten the cold, dry air) > Also, the nasal c. is lined with *cilia*, which move back and forth during breathing, pushing any foreign matter out of the nostrils or down the pharynx (digestion system, excreted with the bodies waste)

The Respiratory System

The primary function of this system is to supply the blood with oxygen to deliver to all parts of the body > Through breathing, we inhale oxygen (O2), and exhale carbon dioxide (CO2) > This exchange of gases is the systems way means of getting oxygen to the blood > This system and the circulatory system are linked; that is, blood carries the O2 from the lungs to all the cells of the body

Respiration: Breathing (2)

The process by which O2 is taken from the external environment > This involves both inhalation and exhalation > The movement of air allows the body to take in the O2 it needs for cellular activities and remove CO2, which is a waste product of cellular respiration * The exchange of O2 and CO2 occurs in the lungs 1. External Respiration 2. Internal Respiration 3. Cellular Respiration

Diffusion

The process by which molecules of a given substance move from an area of relatively high concentration to an area of lower concentration

Smoking

The respiratory system does not deal well with tobacco because of the 4000 different substances it contains > Some of the most hazardous compounds are Tar, Nicotine, Carbon Monoxide (CO), cadmium, nitrogen dioxide, and hydrogen sulfide > Just 1 cigarette slows the motion of cilia for 20 minutes > Tobacco also increases the amount of mucus in the air passages and coughing is the result of attempting to get rid of the extra mucus > The alveoli fill up with air and deflate when we breath --> In healthy lungs they are spongy/springy, and the passageways that lead to the alveoli are unobstructed, wide and open --> In unhealthy lungs (mainly smokers), the air passages are partially blocked, inflamed, narrowed, alveoli is damaged, become looser, saggy, and out of shape > The lungs elasticity is destroyed; this is what makes the expansion and contraction of the lungs less efficient and breathing more laboured and more frequent 1. Tar 2. Disorders 3. Second-Hand Smoke

Total Lung Capacity

The total amount of air in the lungs that it can hold; the amount of air in the lungs after a deep inhalation > It is equivalent to the vital capacity plus the residual capacity > Avg. total lung capacity is 6000mL

Vital Capacity

The total amount of air that can be exhaled in one breath; the maximum amount of air that can be forcibly exhaled after breathing in as much as possible * This volume of air can be up to 10x more than you would normally exhale

Pharynx (1)

The two openings of the airway (nasal c. & the mouth) meet at the throat, located at the back of the nose and mouth > This is part of the digestion and respiratory system because it carries food and air > At the bottom, the pathway divides in two 1. Passage for food (esophagus to stomach) 2. Passage for air (trachea) > The *epiglottis* (small flap of tissue) covers the air passage when we swallow > When air enters the esophagus, it collects and is removed the process of eructation(1 - burping) > When food goes into the trachea instead of the esophagus, coughing occurs to help dislodge the particle of food

Breathing Controls and Malfunctions

There are two controls for breathing, both in which are involved in holding your breath 1. Automatic Response 2. Voluntary Response Although in automatic breathing, you can breathe while you sleep, it sometimes malfunctions ADULTS: Sleep Apnea (stoppage of breathing for as long as 10 seconds - some as often as 300 times per night) INFANTS: may result in SIDS - sudden infant death syndrome

Never Cells

These cells in the airways also sense the presence of unwanted substances such as pollen, dust, noxious fumes, water, or cigarette smoke > These cells then signal the respiratory centre to contract the respiratory muscles, causing you to sneeze or cough > Coughing or sneezing cause air to be rapidly and violently exhaled from the lungs and airways, removing the offending substance

Second-Hand Smoke

This may just as dangerous > Some studies suggest that smokers develop immunity to smoke that non-smokers do not > Approximately 3000 Canadians die each year from the exposure to second-hand smoke

Diaphragm

This plays a lead role in breathing > When this structure moves downward, toward the abdomen, and the rib muscles pull the ribs upward and outward, enlarging the chest cavity and pulling air in through the mouth or nose > Air pressure in the chest cavity is reduced then and with gas flowing from high pressure to low air pressure, the environments air would flow through the nose or mouth > When we breathe out this structure moves upward, forcing the chest cavity to get smaller, and pushing the gases in the lungs up, and out through the nose and mouse > Air pressure in the lungs is now increased, so air flows from the lungs, through the nose and mouse, up and out of the respiratory system back into the environment

Cilia

Tiny hair-like projections that move liquids and regulate systems in the respiratory system: *Nasal Cavity* - on this structures epithelial lining to further filter and moisten the air --> pushes any foreign matter out the nostrils or for waste down the pharynx *Trachea* - on this structure, it sweeps fluids and foreign particles out of the airway to keep the lungs safe *Lining of Bronchi* - Right on the walls under the mucous membranes and removes foreign particle

Structure of the Human Respiratory System (2)

We breathe about 20 000 times a day > the respiratory system includes: nose, throat, larynx, trachea, and lungs The Process 1. Nasal Cavity (nostril, cilia, epithelial lining) 2. Mouth (larynx/voice-box) 3. Trachea (bronchi) 4. Thoracic Cavity (lungs, ribs, diaphragm, abdominal cavity) * Although we cannot see it, the air we breathe is made up of several gases > The oxygen concentration = 21% and is the most important gas to keep us alive for body cells to have energy and growth (otherwise the body cells would die)

Things that affect Lung Function (2)

We breathe about 20 000 times each a day, inhaling about 16 kilograms (six times more food and liquid consumed) 1. Air Pollution 2. Smoking

Smoking Effects

When cigarette smoke is inhaled, about 1/3 of the smoke particles will remain within the alveoli, damaging their walls > Smoking causes a reduction in the working area of the respiratory surface and flexibility, leading to the disease emphysema --> A condition in which the alveoli lose their elasticity and crack or explode, thus decreasing the surface area for gas exchange