topic 7 -respiratory system

1. Understand the processes of respirations

2. Describe the functions of the respiratory system

3. Describe the structural and functional anatomy of the respiratory system

4. List and label the basic components of the respiratory system

5. Explain the basic structure and function of the respiratory system

6. Explain how and where gas exchange occurs in our lungs

7. Define pulmonary ventilation, expiration and inspiration

8. Explain how the respiratory muscles cause volume changes during breathing

functions of respiratory system

• regulation of blood pH by changing carbon dixoide levels

• production of chemical mediators

• voice production

• olfaction (smell)

• protection

respiration processes

1. Ventilation; the movement of air into and out of the lungs;

2. Gas exchange between the air in the lungs and the blood; sometimes called external respiration;

3. The transport of oxygen and carbon dioxide in the blood; and

4. Gas exchange between the blood and the tissues, sometimes called internal respiration.

classifiying the respiratory system

Two ways of classifications

• Structural

  • Upper Respiratory Tract

  • Lower Respiratory Tract

• Functional

  • Conducting Zone

  • Respiratory Zone

structural classification ww

The upper respiratory tract includes the external nose, the nasal cavity, the pharynx (throat) with its associated structures, and the larynx (voice box). These passageways filter, warm, and humidify incoming air, protecting the more delicate surfaces of the lower respiratory system. They also reabsorb heat and water from the outgoing air.

The lower respiratory tract includes the trachea (windpipe), the bronchi and smaller bronchioles, and the lungs.

the larynx

• The larynx is made up of nine cartilages

• You can feel the main one - the thyroid cartilage a.k.a 'Adam's Apple'

• Other important ones include the epiglottis - the only one that is elastic cartilage

• Your vocal folds (vocal cords) are not cartilage, but are ligaments

• Inflammation here is known as laryngitis! 

the trachea

• The trachea is also known as the 'windpipe'

• Reinforced with cartilage rings to stop it from collapsing - providing an open passageway for air

• There are some smooth muscle in the posterior wall

• Important in coughing - prevents food/liquid going in the lungs

functional classification

The conducting zone (or region) is exclusively for air movement and extends from the nose to the bronchioles.

The respiratory zone (or region) is within the lungs and is where gas exchange between air and blood takes place.

lungs

The lungs are the principal organs of respiration, and on a volume basis they are among the largest organs of the body. Each lung is conical in shape, with its base resting on the diaphragm and its apex extending to a point approximately 2.5 cm superior to the clavicle. The right lung is larger than the left and weighs an average of 620 g, whereas the left lung weighs an average of 560 g.

The hilum is a region on the medial surface of the lung where structures, such as the main bronchus, blood vessels, nerves, and lymphatic vessels, enter or exit the lung. All the structures passing through the hilum are referred to as the root of the lung.

The narrow superior portion of each lung, the apex, is just deep to the clavicle. The broad lung area resting on the diaphragm is the base.

The right lung has three lobes, and the left lung has two to accommodate an indentation called the cardiac notch. This arrangement allows the heart to lie between the lungs. The lobes are separated by deep, prominent fissures on the surface of the lung (see Figure 8), and each lobe is supplied by a lobar bronchus.

The word fissure means a cleft or groove which divides the lung into lobes. The right lung has two fissures, therefore there are three lobes. The left lung only has one fissure – therefore two lobes.

respiratory zone

mechanics of breathing

Keep this rule in mind about the mechanics of breathing: Volume changes lead to pressure changes, which lead to the flow of gases to equalise the pressure.

The two phases of breathing include: inspiration, when air is flowing into the lungs, and expiration, when air is leaving the lungs.

inspiration

When the inspiratory muscles (diaphragm and external intercostals) contract, the size of the thoracic cavity increases. As the dome-shaped diaphragm contracts inferiorly, the superior-inferior dimension (height) of the thoracic cavity increases. Contraction of the external intercostals lifts the rib cage and thrusts the sternum forward, which increases the anteroposterior and lateral dimensions of the thorax. The lungs adhere tightly to the thorax walls (because of the surface tension of the fluid between the pleural membranes), so they are stretched to the new, larger size of the thorax.

As intrapulmonary volume (the volume within the lungs) increases, the gases within the lungs spread out to fill the larger space. The resulting decrease in gas pressure in the lungs produces a partial vacuum (pressure less than atmospheric pressure outside the body), which causes air to flow into the lungs. Air continues to move into the lungs until the intrapulmonary pressure equals atmospheric pressure. This series of events is called inspiration (inhalation).

pulmonary ventilation

Pulmonary ventilation is the physical movement of air into and out of the respiratory tract. Its primary function is to maintain adequate alveolar ventilation—movement of air into and out of the alveoli. Alveolar ventilation prevents the buildup of carbon dioxide in the alveoli. It also ensures a continuous supply of oxygen that keeps pace with absorption by the bloodstream.