M5 - Respiratory System

nasal cavity

Filters, warms, and moistens incoming air

Inside the nose

pharynx

Common air passage from nose/mouth to larynx

Behind the nasal and oral cavities (throat)

epiglottis

Prevents food and liquid from entering the airway during swallowing

Flap at the base of the tongue, above the larynx

larynx

produces sound, protects lower airway

Between the pharynx and trachea Keeps airway open

trachea

Conducts air to and from the

From larynx to bronchi lungs

lungs

Gas exchange (oxygen in, carbon dioxide out)

Thoracic cavity, on either side of the heart

pleura

The pleura is a two-layered membrane surrounding the lungs, with one layer (parietal pleura) lining the chest wall and the other (visceral pleura) covering the lungs, creating a small space filled with lubricating fluid (pleural fluid) that allows the lungs to move smoothly during breathing. It's located within the chest cavity, separating the lungs from the thoracic wall

parietal pleura

Reduces friction during breathing

Lines the inner chest wall

visceral pleura

Reduces friction and allows lungs to move smoothly

Covers the surface of the lungs

bronchi

Conduct air into the lungs

Branches off the trachea into each lung

bronchioles

Regulate airflow to alveoli

Smaller branches within the lungs

alveoli

Site of gas exchange

End of bronchioles in the lungs

pulmonary capillaries

Exchange oxygen and carbon dioxide with alveoli

Surround alveoli

cilia

Move mucus and trapped particles out of the airway

Lining of nasal cavity, trachea, and bronchi

cartilage

functions as a shock absorber, reduces friction between joints, and provides structural support for body parts like the nose and ears

A serous membrane (serosa)

is a thin, double-layered, lubricating membrane that lines closed body cavities and covers internal organs to reduce friction

What type of membrane lines the respiratory tract?  What are the functions of this membrane?

Mucous membrane

• Secretes mucus to trap dust, microbes, and debris

• Moistens and warms inhaled air

• Protects underlying tissues

• Cilia move trapped particles upward toward the pharynx for removal

What is the function of the eustachian tubes?

Drain fluid from your middle ear

Equalize air pressure in your middle ear

Protect your middle ear

Explain the anatomical difference between the right and left lungs

Right lung

• shorter, wider, and heavier

• 3 lobes (superior, middle, inferior)

• 2 fissures

Left lung

• narrower, and lighter

• 2 lobes (superior, inferior),

• 1 fissure

• has a cardiac notch to accommodate the heart.

The right lung lies over the liver, while the left provides space for the heart and the aorta.

How are the lung surfaces protected from irritation due to breathing movements?

a double-layered membrane system containing a specialized, slippery lubricant. This mechanism ensures that the lungs can expand and contract smoothly against the chest wall without damage.

Inspiration and Expiration

Inspiration (inhalation):

• Diaphragm contracts and moves downward

• External intercostal muscles contract → ribs move up and out

• Thoracic cavity volume increases

• Intrapulmonary pressure decreases

• Air moves into the lungs

 

Expiration (exhalation):

• Diaphragm relaxes and moves upward

• Intercostal muscles relax → ribs move down and in

• Thoracic cavity volume decreases

• Intrapulmonary pressure increases

• Air moves out of the lungs

Recall the name of the serous membrane in the thoracic cavity.

pleura

Which layer of the serous membrane lines the thoracic cavity?

The parietal pleura

What is unique about the pressure in this space?

The pressure in the pleural cavity is negative (sub-atmospheric).

This negative pressure keeps the lungs expanded and adhered to the chest wall and prevents lung collapse during normal breathing.

What is the space between the two layers of the serous membrane called?

pleural cavity (pleural space)

Which layer of the serous membrane covers the lung tissue?

visceral pleura

What muscles perform the function of normal breathing?

External intercostal muscles: are primary muscles of inspiration that elevate the ribs and sternum, increasing the thoracic cavity's volume and decreasing internal pressure to pull air into the lungs

The muscle that divides the thoracic and abdominal cavities also has a role in breathing.  What is the name of this muscle and how does it assist in breathing? 

Diaphragm: is the primary, dome-shaped muscle located below the lungs that enables breathing by contracting and flattening to expand the chest cavity, drawing air in (inhalation)

Organs in Thoracic Cavity

heart, lungs, thymus, trachea, and esophagus

Alveoli

are tiny, balloon-shaped air sacs at the end of the bronchioles in the lungs, acting as the primary site for gas exchange between the respiratory and circulatory systems

Arterial blood

is bright red, oxygen-rich blood pumped from the heart under high pressure to supply organs

Venous blood

is dark red, deoxygenated blood returning to the heart under low pressure

arterial blood gases

are a crucial blood test measuring oxygen, carbon dioxide, and pH in blood from an artery, assessing lung function, oxygenation, ventilation, and the body's acid-base balance (acidosis/alkalosis).