The Respiratory SystemQuestions to Ponder About….

1) What is respiration?Before:

After:

2) Why do we need to breathe?Before:

After:

3) What is it that we breathe in and out of our lungs? (What substances?)Before:

After:

4) Why do we need oxygen?Before:

After:

5) How is air brought into and out of our lungs? Through which mechanism(s)?Before:

After:

Cellular Respiration

Did you know that you can survive weeks without food and days without water, but only a few minutes without oxygen?

But why? How come?

Let’s first review the concepts of cellular respiration.

Cellular Respiration Definition: - The conversion of carbohydrates (glucose) in the presence oxygen to release energy in

the form of adenosine triphosphate (ATP). - This process is carried out in the mitochondria- Required for all cellular activities within the body

Cellular Respiration Chemical Equation:

C6H12O6 + O2 H2O + CO2 + ATP

Adenosine Triphosphate (ATP)

- Organic molecule that stores and releases chemical energy for use in body cells. - ATP can be broken down into ADP and phosphate to release energy.

When you hear the word respiration, you probably think of breathing. However, breathing is just a part of the respiratory process in humans.

Respiration – the processes involved in supplying the body with oxygen and disposing of carbon dioxide.

The Human Respiratory System

Function: To exchange gases (O2 and CO2) between the atmosphere and a respiratory surface in order to maintain homeostasis.

Respiratory Surface: - The area available for the exchange of gases (O2 and CO2)- In humans, the respiratory surface is the lung.

Homeostatic Examples:

1) Cellular functions and activities are fueled by ATP (energy) that is released through the chemical process of cellular respiration. In order for cellular respiration to take place, O2 and glucose must be supplied. A lack of O2 will prevent cellular and thus bodily functions from running properly, and as a result would lead to death.

2) When CO2 is dissolved in the blood, it reacts with water to form carbonic acid, which lowers blood pH levels. Recall that the optimal blood pH is 7.4, which is slightly basic. Therefore, CO2 is a waste product of cellular respiration that needs to be removed from the body.

Oxygen at Altitude…

How much oxygen will there be at Mount Everest?

Contrary to popular belief, the percentage of oxygen in the air doesn’t change significantly with altitude up to about 85km from the earth! At sea level, oxygen comprises approximately 23% the air by weight and on the summit of Mount Everest it still comprises 23% of the air. So what happens?  Why do you feel out of breath when you are up high and why do almost all climbers need oxygen to climb Mount Everest?

The further away from sea level you are, the pressure of the entire atmosphere decreases so in effect, there is less air to breathe.  Less air means less oxygen.  So it’s true that there is less oxygen the higher up you go, but there is also less nitrogen, argon and other gasses that make up the air we breathe.  Nothing changes to the proportions of the gasses in the air, however one breath will deliver less oxygen to your bloodstream, hence you will feel out of breath.

At the summit of Mount Everest at 8850 metres, there will be approximately 33% of the oxygen that is available at sea level.  That’s like climbing up stairs and only getting 1 out of every 3 breathes!  The graph below compares the amount of oxygen available in a given volume of air at altitude relative to the amount at sea level for the same volume.

 

Effects of altitude and lower oxygen levels

On arrival at altitude, there are a number of physiological changes that occur, which enable the body to function optimally in the low oxygen environment.  The process by which individuals gradually adjust is known as acclimatisation.  The initial and most important adjustments are an increase in the frequency and depth of breathing.  This begins to occur at altitudes of just 1500m.  The heart pumps faster and blood pressure rises.  Importantly, red blood cell production increases, resulting in an increased haemoglobin concentration, which is required to pick up oxygen and transport it around the body.  These mechanisms enable the body to continue to deliver enough oxygen to each cell, despite the lower oxygen levels.  At sea level our blood is 98% saturated with oxygen and this decreases to 89% at 3000m and reaches as low as 40% on the summit of Everest.

Without proper acclimatisation, there are three different types of illness which can occur; acute mountain sickness (AMS), high altitude cerebral oedema, and high altitude pulmonary oedema, with considerable overlap between the syndromes.

Acute mountain sickness is by far the most prevalent of these and usually precedes the other two life-threatening illnesses.  In most cases, AMS is relatively mild and is treated with rest and fluids.  In fact, in the Mount Everest region, approximately 50% of trekkers who walk to altitudes above 4000m over five days develop AMS, while 84% of those who fly directly to 3860m are affected in some way.  At present, it seems that there are no particular factors that make people are any more or less susceptible to developing AMS – regardless of age, sex, fitness levels, etc.  Its symptoms (in decreasing order of frequency) include;

Headaches Fatigue Nausea Vomiting Loss of appetite Dizziness Irritability Disturbed Sleep

These symptoms gradually appear 12-24 hours after arrival at altitude and begin to decrease in severity by the third day. The number of symptoms as well as their severity, rapidity of onset, and duration varies markedly among individuals.

Question Analysis

1. Why might someone need to take in deeper breaths as s/he climbs to higher altitudes?

2. What is the chemical equation for cellular respiration? How does being at higher altitudes hinder this chemical reaction from proceeding? And as a result, what happens to the body?

3. Higher elevation causes a homeostatic imbalance within the body. How does the body compensate to normalize these changes?

Components of the upper Respiratory Tract

- Nose - Nasal Cavity - Mouth - Pharynx- Epiglottis - Larynx

Nose

- As you inhale air, small specks of dirt are trapped by tiny hairs in your nose. The nose hairs associated with the moisture inside the nose stops the small specks of dirt from going further in your body.

Nasal Cavity

- Is a large, air-filled space located behind the nose. It prepares the air filters, warms up, and moistens the air) to be received by the other areas of the respiratory system.

- It has hair, mucous membranes and cilia (tiny hairs) that prevent dust, bacteria and other foreign particles from entering the lungs

Mouth

- Air can also be taken in through the mouth. Not as good as inhaling air through your nose because it does not filter or warm up the air as the nose does.

Pharynx (Throat)

- It is situated behind the mouth and serves both the respiratory system (receives air from the nasal cavities and move air into lungs) and digestive system (moves food into your stomach).

Larynx (Voice Box)

- Is the portion of the respiratory tract containing the vocal chords. It is located between the pharynx and the trachea.

Epiglottis

- Is a flap of cartilage that lies at the top of the larynx. - At rest: the epiglottis is upright and allows air to pass - During swallowing: it folds back to cover the entrance to the larynx, preventing food and

drink from entering the windpipe (trachea)

Components of the lower respiratory tract

- Trachea (windpipe)- Bronchi- Lungs- Alveoli- Intercostal Muscles- Diaphragm

Trachea (Windpipe)

- Is a tube like structure connects the larynx to the bronchi.

Bronchi- The trachea branches off into two main bronchi(right and left) which lead to your right

and left lungs respectively. Each bronchus enters its respective lung and begins on a series of branches, called bronchioles.

Lungs

- Are found within chest cavity. Humans have 2 lungs. The left lung has 2 lobes, right lung has 3 lobes. The left lung has 2 lobes making it slightly smaller to make room for the heart. The lungs also contains thousands of alveoli (tiny air sacs) that inflate with air. The surface area of a typical human lung can cover a Tennis Court!

Alveoli (Air Sacs)

- Are located at the end of bronchioles. They are the sacs in the lungs where gas exchange occurs.

- Around the alveoli are microscopic capillaries that bring carbon dioxide from the heart via pulmonary artery and delivers oxygen back to the heart via the pulmonary vein.

Practice! Try to fill in the boxes without looking at the diagram.

http://www.lung.org/

Lungs 101: How Does Smoking Hurt Your Lungs?(June 3, 2008)—Smoking seriously damages your lungs in several important ways.  It interferes with your lungs’ natural cleaning and repair system. Smoking destroys the tiny hairs known as cilia that line the upper airways and protect against infection. Normally, your airways have a thin layer of mucus and thousands of cilia. The mucus traps the tiny particles of dirt and pollution you breathe in, while the thousands of cilia move like a wave to push the dirty mucus out of your lungs. When you cough, swallow or spit up mucus, the dirt leaves your lungs.

Because smoking destroys cilia, the dirt and pollution stays in your lungs, along with chemicals from cigarette smoke. This gunk in your lungs can put you at risk for developing lung cancer, chronic obstructive pulmonary disease (COPD), chest infections and chronic cough.

Smoking also damages the air sacs, or alveoli, in the lungs, which makes it difficult to breathe. The alveoli at the ends of your airways are like little stretchy balloons. When you breathe in, the alveoli help absorb oxygen, and when you breathe out, they help get rid of the waste gas, carbon dioxide. When you smoke, the alveoli become less stretchy, so it’s more difficult for your lungs to take in oxygen and get rid of carbon dioxide. As alveoli are destroyed, the lungs transfer less and less oxygen to the bloodstream, causing you to feel short of breath

If you’re a smoker and you feel any of the following symptoms, you are experiencing signs of lung damage:

feeling out of breath when you walk up a short flight of stairs coughing  spitting up mucus  repeat chest infections

See your doctor right away for help in quitting and treating your symptoms—if you don’t, these symptoms will just keep getting worse.

Question Analysis

1. What does smoking damage?2. What is the function of cilia and mucous?3. Why might shortness of breath be prevalent amongst smokers?

Four respiration processes

- Breathing (ventilation): air into and out of lungs- External respiration: gas exchange between alveoli and blood (capillaries) - Internal respiration: gas exchange between blood and cells (and tissues)- Cellular respiration: oxygen use to produce ATP and carbon dioxide (waste)

Gas exchange

- Physical method that organisms have for:o Obtaining O2 from their surroundingso Removing excess CO2 from their bodies

External Respiration

- Gas exchange between the blood and alveoli- Gas exchange in an alveolus occurs by simple diffusion.- Recall: What is simple diffusion?

o The movement of a substance from an area of higher concentration to an area of lower concentration (no energy expended)

Steps in Gas Exchange (In the Lungs)

A. Oxygen (O2) is brought into the lungs via inspiration, where it comes into contact with the surface of the alveolus.

B. There is a higher concentration of oxygen within the alveolus than compared to the capillary. Thus, oxygen will move down its concentration gradient (high to low concentration) into the capillary. Water is needed at the surface between the alveolus and the capillary to facilitate the diffusion of gases (O2 and CO2).

C. At the same time, CO2 in the blood diffuses across the membrane and into an alveolus. This occurs in the opposite direction to oxygen.

D. The CO2 is then sent back up the airway to be expelled to the outside via expiration

Internal Respiration

- Gas exchange between the blood and cells- Gas exchange between cells and capillaries occurs by diffusion

Steps in Gas Exchange (In body cells / tissues)

A. Oxygen is transported to body cells via the bloodstream by red blood cells. B. There is a higher concentration of oxygen in the blood than within body cells. Thus, oxygen moves into body cells.

C. There is a higher concentration of carbon dioxide within body cells than compared to the blood. Thus carbon dioxide will move out of body cells and into the bloodstream.

D. Carbon dioxide is carried in the bloodstream back to the lungs to be expelled from the body.

The mechanics of breathing

Definition: Breathing – the mechanism by which mammals ventilate their lungs (bring air in and out).

The forcing of air into and out of the lungs by breathing movements is necessary to increase the exchange of gases with the environment. The diffusion of oxygen from the external atmosphere into the nose, through the several parts of the respiratory system, and through the alveoli would be too slow to supply a large, active organism with enough oxygen for its needs or rid the body of waste carbon dioxide rapidly enough.

Ordinarily, breathing movements are involuntary; they proceed without thinking about it. They also continue when a person is sleep or unconscious. This is necessary because the body does not store oxygen, and more than momentary cessation of breathing can be lethal. It is possible to exercise voluntary control over breathing. A person can hold his/her breath, or breathe more deeply or more shallowly than usual, but he/she soon tires of this, involuntary control takes over. Breathing consists of two processes, inspiration and expiration.

Inspiration – the period when air flows into the lungs

During inspiration, the following events occur:1) The ribs move up and out2) The diaphragm moves down3) The intercostal muscles contract

o When the above happens it increases the volume of the chest cavity. This creates a low pressure inside the chest. The pressure inside the chest is less than the pressure outside the body.

o Air “rushes” into the lungs from the outside.o The lungs “inflate”

Expiration – the period when gases exit the lungs

During expiration, the following events occur:1) The ribs move down and in2) The diaphragm moves up3) The intercostal muscles relax

o When this happens, it decreases the volume of the chest cavity. This creates a high pressure inside the chest. The pressure inside the chest is greater than the pressure outside the body.

o Air is forces out of the lung.o The lungs deflate

Some Terms

Diaphragm A muscle that helps separates the upper part of the body (chest cavity) from the lower part of the body (abdominal cavity).

Function: The diaphragm works along with the intercostal muscles and ribs to help create low and high pressure within the chest cavity to aid with breathing.

Intercostal muscles A set of muscles attached to the ribs within the chest cavity that control the movement of the rib cage.

Function: Work with the diaphragm to create high and low pressure within the chest cavity to aid with breathing.

Lung Capacity

A singer with a well-trained voice can hold a single note for over 30 seconds. To do this, the singer must be able to hold a relatively large amount of air in his or her lungs and release it in a slow, controlled manner. This ability is determined, in part, by the singer's vital capacity.

A person's vital capacity

Vital capacity is also measured as the sum of three volumes of air: the tidal volume; the inspiratory reserve; and the expiratory reserve.

The tidal volume

The inspiratory reserve volume

The expiratory reserve volume

Vital Capacity is calculated as follows

Respiration and Homeostasis

Medulla Oblongata – Is a structure found in the brain that helps to maintain homeostasis. It responds to higher levels of carbon dioxide in your blood and sends a signal to rib muscles and diaphragm to contract.

Chemoreceptors – Are located at the surface of the medulla oblongata. These are sensory receptor that transduces a chemical signal into a potential action.

Blood pH regulation

Recall that depressed respiratory rates can cause a decrease in blood pH due to the buildup of carbonic acid.

Hyperventilation, which is a high breathing rate that expels carbon dioxide faster than it is produced, can cause the blood pH to rise.

Respiratory System Defense Mechanisms

Coughing

Coughing is a reflex action in response to irritation of the throat, trachea, lung or pleural membrane. It can also be caused by nervousness, or it can be voluntary. There is a rapid contraction of the chest and diaphragm muscles causing a sharp intake of air. The epiglottis closes as the chest and diaphragm muscles relax. This causes a buildup of air pressure inside. The epiglottis suddenly opens and the air blows out carrying the irritating particles with it. The main function is to protect the lungs from harmful particles that may be inhaled.

Sneezing

Sneezing is the sudden expulsion of air through the nose. Irritation of the lining of the nasal cavity usually stimulates the sneezing action. The air is taken in by normal breathing and then interrupted. The opening to the mouth is closed off by the soft palate and air is forced out through the nose carrying the irritating particles with it. During a sneeze,

the heart stops momentarily.

Yawning

Yawning is a combination of psychological and physical reactions resulting in an involuntary stretching of the mouth accompanied by a large intake of air. The air is then exhaled as the mouth closes. It may be the result of a decrease in breathing rate due to tiredness, boredom, or drug action. Since the body requires more oxygen there is a sudden intake of air in the form of a yawn.

Respiratory System Review

1. What is cellular respiration? Where does it take place?2. List the reactants and products of cellular respiration in separate categories.3. Why do living things need oxygen?4. How is energy released from a molecule of ATP?5. What is internal respiration?6. What is external respiration?7. Where does gas exchange occur?8. What is the order for the path of air entering into your lungs? In other words, what

organs/structures does air pass through in order?9. What’s the main difference between breathing through your nose and breathing through your

mouth?10. What happens to the diaphragm and intercostal muscles when you breathe in? when you

breathe out?11. Where is sound produced?12. What causes inspiration and expiration?13. Contrast lung air pressure during inspiration and expiration.14. What are tidal volume, inspiratory reserve volume, expiratory reserve volume and vital

capacity?Practice! Fill in the boxes with the correct terms.

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Across2. One of two places where air enters your body.4. When we exhale we breathe this plus carbon dioxide.7. You do this when something irritates your nose.8. You do this when you don't get enough oxygen to your blood.11. A gas that you breathe out. It is a waste gas.14. The place where oxygen enters the blood.16. You do this when something irritates your diaphragm.17. Breathe out.19. Large muscle that controls the lungs.

Down1. This prevents food from going down your lungs.3. All animals need this gas to make energy from food.5. Scientific name for the windpipe.6. Inhale and exhale.9. Common name for the trachea.10. Fish have these instead of lungs.11. You do this when something irritates your trachea or bronchi.12. Two tubes that connect the trachea to the lungs.13. Breathe in.15. One of two places where air enters your body.18. What we breathe.