THE RESPIRATORY SYSTEM

The Respiratory System

• are organs that deliver oxygen to the circulatory system for transport to all body cells.
• the intake of oxygen and removal of carbon dioxide
• helps regulate the balance of acid and base in tissues , a process crucial for the normal functioning of cells. It protects the body against disease-causing organisms and toxic substances inhaled with air.
• also houses the cells that detect smell, and assists in the production of sounds for speech
• work together to deliver oxygen to cells and remove carbon dioxide in a two-phase process called respiration.

Respiration – an exchange of oxygen and carbon dioxide

Functions of the Respiratory System

•       Breathing process

•       Exchange of Oxygen and Carbon Dioxide

•       Enable speech production

•       Supplies the blood with oxygen so that the blood can deliver oxygen to all parts of the body

•       Removes carbon dioxide waste that cells produced

Two Phases of Respiration

1. External Respiration

·      is the exchanges of gases between the atmosphere and blood

·      this involves the lungs

·    the oxygen from the air goes into the lungs through the respiratory tract. In the capillaries oxygen joins the blood. At this point, the level of oxygen is higher in the alveoli of the lungs

·    the blood that leaves the lungs is called oxygenated blood, since it is rich in oxygen

·      carbon dioxide moves from the blood to entering the lungs and out into the air. The blood entering the lungs is said to be deoxygenated, it is rich in carbon dioxide

 

2. Internal Respiration

·      is the exchange of gases between the blood and the body tissues

Breathing – is a mechanical process that helps get air into and out of the lungs

Two Stages of Breathing

1. inspiration – or the intake of air
• during inspiration, you breath in or inhale to bring a fresh supply of air into the lungs
• inhalation brings air from outside the body into the lungs. Oxygen in the air moves from the lungs through blood vessels to the heart, which pumps the oxygen-rich blood to all parts of the body. Oxygen then moves from the bloodstream into cells, which completes the first phase of respiration. In the cells, oxygen is used in a separate energy-producing process called cellular respiration, which produces carbon dioxide as a byproduct.

 

2. expiration – the breathing out of air

·      during expiration, you breath out or exhale to get rid of carbon dioxide or waste gases not needed by the body

·      begins with the movement of carbon dioxide from the cells to the bloodstream. The bloodstream carries carbon dioxide to the heart, which pumps the carbon dioxide-laden blood to the lungs. In the lungs, breathing out, or exhalation, removes carbon dioxide from the body, thus completing the respiration cycle.

 

Normal Rate of Breathing

Infants – breathe 30 to 40 times a minute

6 years old – the breathing rate slows down to about 22 times a minute

14 to 25 years old – the rate is further slowed down about 16 to 18 times a minute

 

STRUCTURE OF THE RESPIRATORY SYSTEM

1. Nasal Passages

·      The flow of air from outside of the body to the lungs begins with the nose, which is divided into the left and right nasal passages. The nasal passages are lined with a membrane composed primarily of one layer of flat, closely packed cells called epithelial cells.

·      While transporting air to the pharynx, the nasal passages play two critical roles: they filter the air to remove potentially disease-causing particles; and they moisten and warm the air to protect the structures in the respiratory system.

·   Filtering prevents airborne bacteria, viruses, other potentially disease-causing substances from entering the lungs, where they may cause infection. Filtering also eliminates smog and dust particles, which may clog the narrow air passages in the smallest bronchioles. Coarse hairs found just inside the nostrils of the nose trap airborne particles as they are inhaled.

·     The nasal passages also moisten and warm air to prevent it from damaging the delicate membranes of the lung. The mucous membranes of the nasal passages release water vapor, which moistens the air as it passes over the membranes. As air moves over the extensive capillaries in the nasal passages, it is warmed by the blood in the capillaries. If the nose is blocked or “stuffy” due to a cold or allergies, a person is forced to breathe through the mouth. This can be potentially harmful to the respiratory system membranes, since the mouth does not filter, warm, or moisten air.

·      The nasal passages house cells called olfactory receptors, which are involved in the sense of smell. When chemicals enter the nasal passages

2.    PHARYNX

·      Air leaves the nasal passages and flows to the pharynx

·    A short and funnel-shaped tube about 13 cm (5 in) long that transports air to the larynx.

·   Is lined with a protective mucous membrane and ciliated cells that remove impurities from the air.

·     Houses the tonsils and adenoids. These glands pick up and destroy the bacteria trapped in the film of the mucus

·      serves as a passageway for both air and food

·      it is an entrance to both respiratory and digestive tracts

3. LARYNX

·      A structure about 5 cm (2 in) long located approximately in the middle of the neck.

·      the strings of your harp are the vocal cords some people call this structure Adam’s apple

·     it is a small cave of muscle in the front of the neck, a little below the back of the tongue

·      the primary role of the larynx is to transport air to the trachea

·     it plays a primary role in producing sound; it prevents food and fluid from entering the air passage to cause choking; and its mucous membranes and cilia-bearing cells help filter air

·      Food and fluids from the pharynx usually are prevented from entering the larynx by the epiglottis, a thin, leaflike tissue. The “stem” of the leaf attaches to the front and top of the larynx.

4. TRACHEA OR WINDPIPE

·      is a tough muscular tube supported by the rings of cartilage 

·      is also lined with cilia and fluid that trap germs and other materials from the air

·      A tube about 12 to 15 cm (about 5 to 6 in) long located just below the larynx. The trachea is formed of 15 to 20 C-shaped rings of cartilage. The sturdy cartilage rings hold the trachea open, enabling air to pass freely at all times.

·      The base of the trachea is located a little below where the neck meets the trunk of the body. Here the trachea branches into two tubes, the left and right bronchi.

5. BRONCHI

·     Are two smaller pipes from the trachea. One leads to the right lung, the other to the left

·      tube leading from the windpipe to a lung, which provides for the passage of air

·      narrow tube inside the lungs that branches off the main air passages bronchi

6. ALVEOLI

·      a cluster of microscopic, balloonlike air sacs

·      these tiny air sacs perform the main job of the lungs

·  its walls are thin and moist that is why gases can easily diffuse across the membrane of the alveolus

·      deliver oxygen to the circulatory system and remove carbon dioxide

·    The alveoli number about 150 million per lung and comprise most of the lung tissue.

·    Are arranged in grapelike clusters, and each cluster is surrounded by a dense hairnet of tiny, thin-walled capillaries.

7. LUNGS

·      A pair of elastic, spongy organs used in breathing and respiration.

·    The lungs occupy a large portion of the chest cavity from the collarbone down to the diaphragm. They are separated by the heart, blood vessels, and the esophagus

·      it is dome-shaped or cone-shaped with its base [pointing downward, resting on the diaphragm, or sheet of muscle, below

·      At birth the lungs are pink, but as a person ages, they become gray and mottled from tiny particles breathed in with the air.

·      The left lung is slightly smaller than the right. It has two main lobes while the right lung has three

·      In the adult human, each lung is 25 to 30 cm (10 to 12 in) long and roughly conical.

 

DISEASES AND DISORDERS OF THE RESPIRATORY SYSTEM

•       Asthma attack

–      May result from exposure to an allergen, cold temperature, exercise, or emotion

•       Atelectasis

–      A collapse of part or all of a lung, caused by a tumor in the thoracic cavity, pneumonia, or injury

•       Bronchitis

–      An infection of the bronchi

•       Carbon monoxide poisoning

–      Occurs from breathing carbon monoxide

•       Chronic obstructive pulmonary disease

–      A group of chronic respiratory disorders including asthma, chronic bronchitis, and pulmonary emphysema

•       Cold

–      A respiratory infection

•       Emphysema

–      The alveoli lose elasticity and become dilated and do not exchange gases well

•       Hantavirus

–      A respiratory condition spread by breathing in materials contaminated by urine or saliva of infected rodents such as deer mice and chipmunks

•       Hay fever

–      A respiratory inflammation caused by allergens such as plants, dust, and food

•       Lung cancer

–      Directly linked to smoking and smoke products

•       Pleurisy

–      An inflammation of the membranes that line the lungs

•       Pneumonia

–      An inflammation of the lungs, in which a buildup of excessive moisture impairs breathing

•       Respiratory distress syndrome

–       A condition that occurs when the alveoli do not inflate properly

 •       Sinusitis

–      An inflammation of one or more of the paranasal sinuses

•       Sudden infant death syndrome (SIDS)

–      A respiratory disorder of newborns

•       Tuberculosis

–      Caused by bacteria that are difficult to destroy, and it can be transmitted through the air

•       Upper respiratory infection

–      Caused by a virus or bacteria in the nose, pharynx, or larynx