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Flashcards in Biology 11 Respiratory system Deck (31):

Function of the respiratory system

• Controls breathing
• Exchanges gases in lungs
• Removes carbon dioxide
• System is connected to circulatory system (pulmonary arteries and veins)
• Diaphragm begins process (contracts→moves down during inhalation/breathe)

O2 inhaled →complex carbohydrates broken into glucose→O2 and glucose undergo chemical reaction to form energy →CO2 produced as a by-product (must be eliminated)


Structures in the respiratory system

• Includes nasal cavity (nose)→Pharynx →Larynx →Trachea →Bronchus→lungs→Bronchi and Bronchioles →Alveoli →rib cage

1. Thin permeable respiratory membrane through which diffusion can occur (lungs)
2. Large surface area for gas exchange (lungs)
3. Good supply of blood (lungs)->pulmonary circuit
4. Breathing system for bringing oxygen-rich air to respiratory system



• Air is inhaled into body
• Only external part of respiratory system

1. Airway for air
2. Moistens and warms entering air →body temperature
3. Filters and cleans air by trapping particles →cilia/hair and mucus
• Mucus secreted by cells of the nasal lining captures most fine particles and airborne chemicals →to remove any inhaled contaminants
4. Olfactory receptors →smell



• Connects the nasal cavity and mouth (located on top of larynx)
• Nasopharynx: location where tonsils are attached
o Swollen tonsils block air passageway →causing a mouth breather→air does not get filtered in mouth breathers→removal of tonsils



• Also known as voice box

1) Provides open airway
2) Director of where air/food goes (trachea or esophagus)
3) Voice Production-vocal cords
i.e: Laryngitis (vocal cord inflammation)



• Windpipe descending from larynx
• Composed of cartilage to prevent trachea from collapsing
• Connects pharynx to lungs
• Lined with mucus producing cells and cilia (trap unwanted material, expelled by coughing)
o Smoking: damages cilia -->no protection
• Choking on food can block trachea →suffocation
• Heimlich Manoeuvre (J- thrusts) uses air (pressure) from lungs to force food out -->choking



• Right and left bronchi (connect trachea with lungs) and lungs
o Right lung: 3 sections
o Left lung: 2 sections

• Located in the thoracic/chest cavity
• Protected by rib cage
• Lined by a ciliated, mucus-producing epithelium that helps defend body against respiratory infections

• Function: to extend passageway of air to lungs for gas exchange
• Bronchi breaks into smaller branches (23) known as bronchioles →forms respiratory tree

* Stretch Receptors: allow lungs to respond to a change in pressure and then contract or relax. They monitor the amount of stretch in the lungs. If they were damaged, the lungs may become over or under inflated as the lungs would not be able to change their volume →less/more room for air when not needed or needed



• Site of gas exchange
o Small, hollow sacs
o 1 cell thick (allows easy gas exchange)
o Around 300 million alveoli in lungs
o Alveoli ducts connect with bronchioles
o Alveolar ducts join to little clusters of alveolar sacs
o Do not grow new alveoli (therefore if damaged, will not grow new)
o Capillaries surround alveoli and help gas exchange (gas exchange via diffusion)
o Enormous surface area allows for efficient diffusion and gas exchange
• Alveoli (many); alveolus (single)


Gas Exchange

• Works on pressure gradients
o Area of high pressure to area of low pressure (down gradient)
• When air is inhaled, the partial pressure of Oxygen is greater in the alveoli than the partial pressure of Oxygen in the capillaries→easier for oxygen to diffuse into capillaries (down gradient)
• The partial pressure of Carbon Dioxide is greater in the capillaries than the partial pressure of Carbon Dioxide in the alveoli→ CO2 diffuse into alveoli = gas exchange

In body cells and tissues:
• Partial pressure of O2 in blood > greater than Partial pressure of O2 in body tissues = O2 diffusion from rbc into body tissues
• Partial pressure of CO2 in blood < lower than Partial pressure of CO2 in body tissues = CO2 diffusion from body tissues into RBC

• O2 and CO2 keep diffusing until there is no net movement of gases due to no difference in partial pressure
• Gas exchange occurs simultaneously



1. Inspiration (inhalation):
• During inhalation, diaphragm contracts (lowers; becomes flat), rib cage expands, and chest cavity enlarges. This results in an increase in the volume of air the lungs can hold and a decrease in the pressure.
o Intercostal muscles help move ribs upwards
• High P to Low P (air flow into body from high P environment)

2. Expiration (exhalation):
• after gas exchange is complete, the diaphragm relaxes, rib cage compresses, and chest cavity gets smaller. This results in a decrease in lung volume and an increase in air pressure. →forces air out
• High P to Low P (air flow from body to environment)

3. Breathing:
• Involuntary response (do without thinking)-->autonomic nervous system
• Delivers O2 to alveoli and removes CO2


How do humans breathe?

•Medulla Oblongata – part of the brain that controls autonomic functions such as breathing, digestion and heart rate (location of the respiratory centre)
o Neurons in the medulla oblongata of the brain stem act as the pacemaker for inhalation, initiating an action potential 10-20 times per minute
o Senses when we need to breathe
•Slower, deeper, More O2
•Faster, shallower breaths, less O2
•Chemoreceptor's (located in heart; carotid and aortic body) detect change in the blood pH → signals brain
o Increase in CO2 causes a decrease in pH (acidic) --> stimulates the Medulla Oblongata --> exhalation in order to get rid of CO2 and inhale to get O2. Not enough O2 for exchange (pH acidic), therefore increase breathing to result in equilibrium -->The respiratory center signals the diaphragm and intercostal muscles and changes the rate and depth of breathing


Lung capacity

volume of air in the lungs

Capacity varies depending on circumstances:
o Sex (males tend to be higher due to body size and larger rib cages)
o Body Size
o Lifestyle (Physical activity→automatically increase depth of breathing, smoking→lower)

• Total Lung Capacity: The maximum volume of air that can be inhaled during a single breath (6000 ml). →Volume of lungs at maximal inflation
• Measured using spirometer

TLC = vital capacity (max amount of air inhaled/exhaled) + residual capacity


Tidal Volume

the normal amount of air from involuntary breathing (small fraction of total capacity)→no extra effort. About 0.5 L
o Still some room for air to be inhaled


Inspiratory Reserve Volume

inspiratory: inhalation
Reserve: extra

Inspiratory Reserve Volume: Amount of air that can be forcibly inhaled after normal inhalation


Expiratory reserve volume

Expiratory: exhalation
Reserve: extra

Amount of air that can be forcibly exhaled after normal exhalation
oStill some air left in lungs; never empty


Residual Volume

volume of air remaining in lungs (always some air left in lungs) after a forced exhalation
o Prevents lungs from collapsing
o Allows for continuous gas exchange between breaths


Vital Capacity

Maximum amount of air that can be inhaled or exhaled


Oxygen usage

Oxygen Usage:

VO2: The rate at which oxygen is used/converted into energy in the body
o Function of the amount of oxygen delivered to the body in a given time (rate O2/time)
o At any given time (typically rest)

VO2max: The maximum rate at which oxygen can be used during sustained intense physical activity
o Measured in millliters per kilogram per minute (mL/kg/min)
• Ex: 25 mL of O2 are used per Kg per minute.
o Calculated using a spirometer

VO2max should be higher -->need more O2 to make energy to function
To make energy, you need O2

*VO2 shows fitness level (ability of lungs to efficiently use oxygen)
• Frequent exercise results in stronger intercostal muscles and diaphragm (cage) →bigger→more air capacity
• Muscle memory →use O2 more efficiently = higher VO2
• Burn more glucose (O2 and glucose react)
• Produce more energy (ATP)


Concepts for exercise

• Exercise results in the need for more oxygen for muscles to function
• Body responds by breathing more quickly and deeply
• Cells in muscles use more oxygen
• Thus, respiratory speeds up to supply blood with oxygen and get rid of carbon dioxide waste
• Lungs work harder to keep up supply
• When body has high levels of carbon dioxide, breathing rate increases so waste product can be eliminated more quickly


Smoking effects

• Destroys cilia in lungs (no protection)
o Cilia help sweep mucus with foreign particles out of body (by delivering to mouth to be eliminated)
• Loss of cilia leads to development of “smoker’s” cough (trapped mucus)
o The cilia no longer effectively remove mucus, so the individual must cough it up. Coughing is usually worse in the morning because mucus has accumulated during sleep.
• Result: emphysema (damages air sacs/alveoli) → in short of breath, lung cancer, other problems


Disorder: Lung Cancer

Cancer of lung tissues. Results in a tumour in the lungs
•Different types and stages (of severity and location of cancer)
o Non-small cell lung cancer (NSCLC)
o Small cell lung cancer (SCLC)

• Smoking.
• Second-hand smoke.
• Radon.
• Asbestos.
• Uranium, arsenic & some petroleum products

• Persistent cough.
• Persistent chest pain.
• Coughing up blood.
• Wheezing.
• Shortness of breath.
• Loss of appetite/weight loss
• Hoarse voice.
• Periodic chest infections.

• Chest X-ray.
• Sputum analysis: for lower respiratory tract; used to identify potential bacteria or fungi infection that is affecting lungs or breathing passageways
• Bronchoscopy: use of bronchoscope
• Biopsy.
• CT scan.

• Surgery: Lobectomy (removal of a lung lobe). Pneumonectomy (removal of entire one lung)
• Lung transplant.
• Radiation therapy→kill or shrink cancer cells
• Chemotherapy→uses drugs to stop growth of cancer cells by killing or inhibiting growth of cancer cells


Disorder: Chronic Obstructive Pulmonary Disease (COPD)

Chronic bronchitis & emphysema (Often times individuals have both bronchitis and emphysema)
o Disease that obstructs air-flow on a long-term basis 

Bronchitis: inflammation of the epithelium lining the bronchial tubes
-Inflammation causes secretion of extra mucus and triggers the coughing reflex
-Bacteria can colonize the mucus →more inflammation→more mucus→more coughing→mucus and inflammation prevents sufficient air from reaching the lungs

Emphysema: gradual damage to air sacs (alveoli).
-Tissue-destroying bacterial enzymes digest the thin, elastic alveolar walls, reducing the respiratory surface area →alveoli lose elasticity
-Over time, the lungs become inelastic and distended, resulting in shortage of breath.

Causes: inhaling toxins
• Smoking.
• Second-hand smoke.
• Genetic disorder.
• Air pollution.
• Repeated childhood lung infections.

• Shortness of breath.
• Coughing up mucus.
• Fatigue.
• Periodic chest infections.

• Spirometry: uses spirometer to assess how well your lungs work by measuring how much air you inhale, how much you exhale and how quickly you exhale. Using a device (patient breathes into)
• Chest X-ray→examination of lungs
• Blood test.

Treatment: Cannot be cured, but can be controlled
• Medications.
• Surgery.
• Lung transplant.


Disorder: Tuberculosis (TB)

Bacterial disease that can infect anyone
• TB bacteria can infect lungs as well as the brain, spine, bones and joints.
• Can be fatal if untreated

• Spreads through the air, person inhales TB bacteria, settles in lungs and begin to grow

Symptoms include:
• Chronic cough.
• Chest Pain
• Difficult breathing
• Coughing up fluids or blood.
• Fever.
• Loss of appetite.
• Weight loss.
• Night sweats.

• TB skin test -->PPD: used to determine if someone has developed an immune response to the bacterium that causes tuberculosis (TB). If the individual has TB, then there will be a reaction noticeable on the skin
• Chest X-ray.

• Medications: antibiotics (but take long time)
o However there are drug-resistant TB


Aerobic respiration

Aerobic Respiration: occurs when adequate oxygen is available. Purpose is to provide energy for the body.


Disorder: Asthma

Asthma: CHRONIC inflammation of lungs (bronchi and bronchioles) that results in a narrow passageway for air. Triggered by inhaled toxins (allergens). →difficulty breathing
• Airborne allergens, such as pollen, animal dander, mold, cockroaches and dust mites.
• Respiratory infections, such as the common cold.
• Physical activity (exercise-induced asthma)
• Cold air.
• Air pollutants and irritants, such as smoke



Pneumonia: infection of alveolar sacs (causes inflammation of alveoli)


Parts of the respiratory system

• Nasal Cavity (Nose): chamber where air is moistened, warmed, and filtered, and in which sounds resonate.
• Oral Cavity (Mouth): supplementary airway when breathing is labored
• Pharynx: airway connecting the nasal cavity and mouth with larynx. Also connects to esophagus
• Epiglottis: closes off larynx during swallowing
• Larynx (Voice Box): airway where sound is produced; closed off during swallowing
• Trachea (windpipe): airway connecting larynx with two bronchi that lead into the lungs
• Pleural Membrane: Double layer membrane that separates lungs from other organs; the narrow, fluid-filled space between its two layers has roles in breathing.
• Lungs (two): lobed, elastic organ of breathing; site of gas exchange between internal environment and outside air.
• Intercostal Muscles: at rib cage, skeletal muscles with roles in breathing. There are two sets of intercostal muscles (external and internal).
• Bronchial Tree: increasingly branched airways starting with two bronchi and ending at air sacs (alveoli) of lung tissue.
• Diaphragm: muscle sheet between the chest cavity and abdominal cavity with roles in breathing


Affects of respiratory disorders on respiration processes (breathing, gas exchange)

Lung Cancer:
Tumor damages alveoli→alveoli can no longer function in gas exchange→less O2 being delivered to body

Damaged alveoli→traps air→periodic infections→difficulty exhaling air→shortness of breath

Tumor expands on lungs→less space/volume to hold air

Inflammation of air passages→obstructs air flow→difficult breathing (wheezing)

Alveoli damage→decrease in surface area and ability to perform gas exchange→traps air→difficult to exhale →chest infections Lung

Infection caused by bacteria →inflammation →destroy lung tissue →creates a cavity in the lung→loss of lung function, decrease in ability to hold air, less O2 (from alveoli damage and decrease in lung capacity


Ventilation vs Gas Exchange

Ventilation: Air gets in and out of LUNGS (breathing)

Gas exchange: movement of O2 into blood and movement of CO2 out of the blood (through a respiratory membrane: alveoli and capillaries)

Need ventilation for gas exchange and gas exchange for ventilation


What are immunosuppressive drugs?

Given to transplant patients

-make the patients more susceptible to infections
-prevent the immune system from rejecting the transplanted organ (known as anti-rejection drug)
-must be taken for the rest of the patient's life


Alveoli when damaged...


Ex: emphysema is incurable