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• What is the major function of the respiratory system? Major Organs?

• What is the relationship between the cardiovascular system and the respiratory system?

Chapter 13Respiratory System

• The trillions of cells in our body require an abundant and continuous supply of oxygen to carry out their vital functions.

• The cardiovascular system and the respiratory system share the responsibility for supplying the body with oxygen and disposing of carbon dioxide.

• The respiratory system organs oversee the gas exchanges that occur between the blood and the external environment.

• Transportation of gases is carried out by the cardiovascular system.

Functional Anatomy of the Respiratory System

Organs of the Respiratory system

• Nose• Pharynx• Larynx• Trachea• Bronchi and their smaller branches• Lungs• BLT PLT

• The lungs contain the alveoli which are terminal air sacs.

• Gas exchange only occurs in the alveoli.

• Therefore all other organs of the respiratory system are conducting passageways that allow air to reach the lungs.

The Organs of the Respiratory System

Functions of the Conducting Passageways

• Allows air to reach the lungs

1. Nose

• Air enters through the nostrils or external nares.

• The nose contains two nasal cavities.• Special ciliated cells in the upper

reaches of the nasal cavity act as odor receptors.

• Tear glands drain into the nasal cavity.

• The palate separates the nasal cavity from the oral cavity.

• Function – filter, warm and moisten the air

2. Pharynx

• The pharynx is a muscular passageway commonly called the throat.

• It is a common passageway for food and air.

• The pharynx in superior to the larynx and trachea.

• Tonsils are located in the pharynx.

3. Larynx

• The larynx is also known as the voicebox.

• Function of the larynx: sound production

• The epiglottis: a flap of tissue that prevents food from passing into the larynx

• Parts of the larynx form folds called the vocal folds or the true vocal cords which: vibrate with expelled air giving us the ability to speak

• Glottis – opening to the larynx – epiglottis covers

4. Trachea

• The trachea is also known as the windpipe

• The trachea is lined with cilia. The cilia beat in the direction opposite of the incoming air.

• They propel mucus: loaded with dust particles and other debris, away from the lungs to the throat where it can be swallowed or spat out

• The trachea is rigid because it has C shaped cartilaginous rings

• Tracheotomy – when as incision is made in the trachea to allow air to pass around a blockage

5. Bronchi

• The trachea divides into the right and left primary bronchi

• The bronchi laid into the lungs

• The bronchi branch into a great number of smaller passageways known bronchioles

During an asthma attack:

• Smooth muscle lining the bronchioles constricts and movement of air through the narrowed tubes results in the characteristic wheezing

By the time air has reached the bronchi it

is:

1. Warm2. Cleansed of most impurities3. Well humidified

6. Lungs

• The paired lungs are fairly large organs• They occupy almost the entire thoracic

cavity• The primary bronchi go into the lungs

where they subdivide into smaller and smaller branches (secondary and tertiary bronchi). They finally end in the smallest of the conducting passageways the bronchioles.

• The bronchioles end in alveoli or air sacs.• The alveoli make up the respiratory zone• The lungs are cone-shaped organs. The

right lung has three lobes and the left lung has 2 lobes. The left lung has 2 since the heart is on that side and takes up some of the space.

Capillary Network Diagram

• Each alveolar sac is made up of simple squamous epithelium surrounded by blood capillaries. Gas exchange occurs in the capillaries.

• This layer of tissue and the capillary net create the respiratory membrane (air/blood barrier). Air flows by one side and blood flows by on the other side. Gas exchange occurs by simple diffusion.

• There are approximately 300 million (alveoli). Their surface area is at least 40X that of the skin.

• The lungs are mostly air spaces so they are light and usually float in water – soft and spongy

• Macrophages (WBC) wander in and out of the alveoli picking up bacteria, carbon particles and other debris.

Mechanisms of Breathing

• Respiration: the complete process of supplying oxygen to body cells for aerobic cellular respiration and the reverse process of ridding the body of oxygen

Respiration includes the following components:

1. Breathing

• Inspiration – entrance of air into the lungs

• Expiration – exit of air from the lungs

2. External Respiration

• Exchange of the gases oxygen and carbon dioxide between air and blood

• Occurs in the lungs

3. Internal Respiration

• Exchange of the gases oxygen and carbon dioxide between blood and tissue fluid

• Occurs in the body cells

4. Cellular Respiration

• Production of ATP in cells

Mechanics of Breathing

• Breathing is a completely mechanical process that depends on volume changes occurring in the thoracic cavity

• Volume changes lead to pressure changes, which lead to the flow of gases to equalize the pressure

Ventilation

• The manner in which air enters and exits the lungs

To understand ventilation it is necessary to:

1. There is a continuous column of air from the pharynx to the alveoli of the lungs

2. The lungs lie within the sealed-off thoracic cavity. The rib cage forms the top and sides. The diaphragm forms the floor of the thoracic cavity.

3. The lungs are enclosed by 2 serous membranes called pleural membranes. One layer is attached to the rib cage and diaphragm and the other layer is attached to the lungs. The two layers are very close and are only separated by a little fluid. The pressure in the pleural space is lower than atmospheric pressure.

Inspiration is Active

• Inspiration is triggered by the respiratory center. Impulses are sent by way of the nerves to the diaphragm and the muscles of the rib cage known as intercoastals.

• When relaxed the diaphragm is domed shaped but when it contracts it lowers.

• Nerves also stimulate the intercostal muscles to contract causing the rib cage to move upward and outward

• When the diaphragm contracts and the rib cage moves up and out, the thoracic cavity increases in size. This causes the lungs to expand and air to move in from the nose or mouth.

Expiration is usually passive

• When the nerves stop sending signals, the diaphragm relaxes and resumes its dome shape.

• The abdominal organs press up against the diaphragm and the rib cage moves down and inward

• This causes the elastic lungs to recoil and air to be pushed out.

External and Internal Respiration

• The principles of diffusion alone govern whether oxygen or carbon dioxide enters or leaves the blood

External Respiration cleanses the blood

• External respiration refers to the exchange of gases between air in the alveoli and blood in the pulmonary capillaries

External Respiration occurs in the lungs.

• Carbon dioxide diffuses out of the blood in the lungs.

• Oxygen diffuses into the blood in the lungs.

Internal respiration cleanses tissue fluid

• Internal respiration occurs in the body cells

• Oxygen diffuses out of the blood and into the tissues.

• Carbon dioxide diffuses out the tissues and into the blood

Respiratory Sounds

• As air flows in and out of the respiratory passageways it produces two recognizable sounds that can be picked up with a stethoscope.

1. Bronchial Sounds – produced by air rushing through the large respiratory passageways

2. Vesicular sounds – as air fills the alveoli

• Diseased respiratory tissue, mucus or pus can produce abnormal sounds such as rales (a rasping sound) or wheezing (a whistling sound)

Respiration and Health

Bronchitis: Acute and Chronic

Acute

• Caused by: secondary bacteria infection

• Results in: heavy mucous discharge with much coughing

• Treatment: antibiotics

Chronic

• Caused by: smoking – second hand smoke – irritation to the lining of the bronchi

• Results in: frequent coughing, increased risk of respiratory infections

• Treatment - none

Pneumonia

• Caused by: bacteria or virus infection of the lungs

• Results in: lobes fill with fluid become non-functional

• Treatment - antibiotics

Pulmonary Tuberculosis

• Caused by: Tubercle bacillus – bacteria

• Results in: cysts in the lungs, alveoli burst and replace by inelastic connective tissue

• Treatment: antibiotics – some strains are now resistant

Emphysema

• Caused by: destruction of lung tissue – damage and collapse of lung tissue

• Results in: ballooning or inflation of the lungs due to trapped air, breathless cough, surface for gas exchange decreases, not enough oxygen to hear and body

• Treatment: none

Smoker's Lung - tar coated, causing emphysema

Lung Cancer

• Caused by: smoking• Results in:

thickening of bronchi cells, loss of cilia, dust and bacteria enter

• Treatment: removal of lung piece

The End