Human Respiratory System

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Human Respiratory System

• A system that provides a large surface area for
  the diffusion of O2 into the blood, and the
  diffusion of CO2 out of the blood.

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Parts of the Respiratory System
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Oral and Nasal Cavities

• Structure - openings through which air enters the
  system. Nasal cavity is the chamber behind the
  nose. It contains hairs, cilia, and mucus.
• Function - the nose and nasal cavities have the
  following functions
• (A) air is cleansed by the mucus, cilia, and hair

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• (B) air is heated by blood passing through a
  large number of capillaries just below the mucus
  membranes
• (C) mucus membranes moisten the air
• The cleansing, heating, and moistening of the air
  prevents damage to the delicate lung tissue.

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Pharynx

• Structure - cavity behind the nasal cavity that
  is common to the respiratory and digestive
  systems. It contains two lymph glands adenoids
  and tonsils.
• Function - transports air between the nasal
  cavity/mouth and the trachea.

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Larynx

• Structure - consists of several pieces of
  cartilage. Located inside is elastic tissue
  known as vocal cords.
• Function - the vocal cords vibrate as air goes
  through them producing sound. The pitch of the
  sound produced depends on the length of the vocal
  cords.

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Trachea

• Structure - a tube about 10 to 17 cm long
  containing rings of cartilage which prevent the
  tube from collapsing. At the top is located the
  epiglottis. It is lined with mucus membrane that
  is ciliated.
• Function - a connecting tube that leads air to
  and from the lungs.
• Epiglottis - prevents liquids or solids from
  entering the lungs.
• Mucus membrane - produces mucus that traps
  foreign materials that are then swept out of the
  trachea by the cilia. This material is carried
  away by food passing down the esophagus.

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Bronchi

• Structure - tubes which branch from the trachea
  leading into the two lungs.
• Function - a connecting tube that leads air to
  and from the lung.

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Bronchials

• Structure - small tubes that branch from the
  bronchi inside the lungs.
• Function - connecting tubes that lead from the
  bronchi to the bronchioles.

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Bronchioles

• Structure - yet smaller tubes that branch from
  the bronchials inside the lung.
• Function - connecting tubes that lead from the
  bronchials to the alveoli.

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Lungs

• Structure
• Protected by the ribs, sternum, and spine.
• Surrounded by two membranes called pleura. The
  pleura isolates the lungs and protects the
  delicate tissue. A lubricating fluid is found
  between the two layers allowing the lungs to move
  freely in the chest cavity during breathing.
• Function - contain a variety of tubes and
  chambers where gases are exchanged between the
  lungs and the blood.

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Diaphragm

• Structure - sheet of muscle that separates the
  thorax (chest) and abdomen cavities.
• Function - its movement is responsible for
  breathing.
• Inspiration (inhale) - diaphragm contracts
• Expiration (exhale) - diaphragm relaxes

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Alveoli

• Structure - millions per lung, giving the lungs a
  very large surface area for gas exchange. They
  are found at the ends of the bronchioles and are
  a cluster of microscopic, one cell thick,
  grape-like air sacs. They are moist and
  surrounded by capillaries.
• Function - site of gas exchange between the air
  in the lungs and the blood in the capillaries.

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Alveoli of the Lungs
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Process of Breathing

• Definition - breathing is a mechanical process
  where gases are exchanged between the lungs and
  the atmosphere. Breathing is the first step in
  respiration.
• Breathing occurs due to changes in the pressure
  in the thorax or chest cavity of the body. This
  pressure is controlled by changing the size of
  the thorax. Two structures responsible for
  changing the size of the thorax are

• ribs and rib muscles (intercostal muscle)

• diaphragm

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Inhalation (Inspiration)

• Definition - air enters the lungs
• Process - there are six steps to the process
• (1) rib muscle and diaphragm contract
• (2) ribs move up and out
• (3) diaphragm moves down
• (4) thorax increases in size or volume
• (5) pressure decreases in the thorax due to
  increase in volume. The result is lower pressure
  inside the thorax than outside.
• (6) air rushes into the lungs

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Exhalation (Expiration)

• Definition - air leaves the lungs
• Process - there are six steps to the process
• (1) rib muscle and diaphragm relax
• (2) ribs move down and in
• (3) diaphragm moves up
• (4) thorax decreases in size or volume
• (5) pressure increases in the thorax due to
  decrease in volume. The result is a higher
  pressure inside the thorax than outside.
• (6) air rushes out of the lungs

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Rate of Breathing

• Breathing is an involuntary response controlled
  by a section of the brain called the medulla
  oblongata.
• This structure sends impulses to the intercostal
  muscles of the ribs and diaphragm, causing them
  to contract which produces inspiration.
• When this impulse stops, the intercostal muscle
  and diaphragm relax producing expiration.
• The amount of CO2 in the blood determines the
  rate of breathing.

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• Two sensors located in the circulatory system
  measure the CO2 content of the blood

• carotid artery in the neck

• aorta leading from the left ventricle of the
  heart

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CO2 Level
Rate of Breathing
High
Fast
Slow
Low
Breathing rates vary with age and activity.
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Stages of Respiration

• 1. Breathing
• (previously discussed)

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2. External Respiration

• Definition - exchange of gases between the
  alveoli of the lungs and the blood.
• Process - occurs by diffusion
• O2 goes into the blood from the alveoli
• CO2 goes into the alveoli from the blood

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3. Gas Transport

• Definition - transportation of gas between the
  lungs and body cells.
• Process - the gases enter the blood and combine
  with the protein hemoglobin found on the red
  blood cell (RBC)
• lung ----gt body cells O2 enters the
  bloodstream and combines with the hemoglobin
  forming oxyhemoglobin
• body cells ----gt lung CO2 enters the
  bloodstream and combines with the hemoglobin
  forming carboxyhemoglobin

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CO2 also combines with water on the RBC and in
the plasma, this forms carbonic acid.
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Gas Exchange
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4. Internal Respiration

• Definition - exchange of gases between the blood
  and the cells of the body.
• Process - occurs by diffusion
• O2 goes into the body cells from the blood
• CO2 goes into the blood from the body cells

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5. Cellular Respiration

• Definition and Process both covered previously.

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Diseases of the Respiratory System
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Bronchitis

• Definition - inflammation of the bronchial
  passages. Two forms
• Acute - severe form which involves an infection
  of the air passages.
• Chronic - less severe form which involves an
  irritation of the air passages.
• Symptoms - fever, chest pain, severe coughing and
  often the secretion of sputum.

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Asthma

• Caused by the constriction of bronchial passages
  and swelling of their mucus linings. It is
  triggered by a hypersensitivity to various agents
  within an individuals environment.
• Symptoms - attack begins with pressure in the
  chest, feeling of suffocation, with severe bouts
  of uncontrollable coughing and the secretion of a
  thick mucous sputum.

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Pneumonia

• Caused by the infection in the alveoli resulting
  in the build-up of fluid in the lungs. Two major
  forms are bacterial and viral.
• Symptoms - fever, pain in the chest while
  breathing, cough, and blood-streaked sputum.

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Cancer

• Cancer is the uncontrollable multiplication of
  cells. Cancer may occur in any part of the body,
  and therefore in any part of the respiratory
  system.

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Emphysema

• A progressive disease in which the tissues of the
  lungs lose their elasticity, and therefore the
  volume of air that the lungs are able to handle
  continually decreases.
• The deterioration in the lungs is permanent and
  irreversible.
• Symptoms - severe coughing, shortness of breath,
  and wheezing developing into difficulty in
  breathing. It sometimes results in disability
  and death.

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Influenza

• A viral infection of the respiratory tract,
  especially the trachea. Commonly called flu.
  Reduces a persons resistance making them
  susceptible to further infections such as
  pneumonia.
• Symptoms - sore throat, nasal discharge, fever,
  chills, headache, aching of muscles and joints,
  upset stomach

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Common Cold

• A viral infection of the upper respiratory tract.
• Symptoms - sneezing, headaches, sore throat,
  nasal discharge

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Pleurisy

• Inflammation of the pleura membranes that
  surrounds the lungs. Most cases are due to
  infections, and many are associated with
  pneumonia.
• Symptoms - sharp pain brought on by breathing and
  coughing. Patient breaths shallowly.

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Carbon Monoxide Poisoning

• Definition - Carbon monoxide is a chemical
  compound consisting of one atom of carbon and one
  atom of oxygen (CO). It is an odorless and
  tasteless gas.
• Source - It is produced when organic compounds
  are burned with an insufficient air supply.
• Effects - When inhaled, it combines with the
  hemoglobin on the RBC, preventing absorption of
  oxygen.

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• Symptoms - symptoms are normally mild and include
  nausea, headache, or fatigue. Excessive
  inhalation can be more serious, even fatal.
• Treatment - remove the individual from the source
  of CO. Perform mouth to mouth resuscitation if
  necessary.