Respiratory System

Respiratory Tract• Conducting passageways carrying air to and

from the alveoli– Upper respiratory

• Nasal Cavity• Larynx• Pharynx

– Lower passageways• Trachea• Lungs

– Bronchi– Bronchioles– Alveoli– Diaphragm

nasal cavities (or oral cavity) → pharynx → trachea → primary bronchi (right & left) → secondary bronchi → tertiary bronchi → bronchioles → alveoli

Pathway

Nasal Cavity/Nose• Functions

– Provides an airway for respiration – Moistens and warms entering air – Filters and cleans inspired air – Resonating chamber for speech – Detects odors in the airstream

• Selected anatomical features – Vibrissae (guard hairs) – stiff hairs that filter large particles from the air – Nasal cilia – hair-like projections that propel trapped particles towards the throat

for digestion by digestive enzymes – Rich supply of capillaries warm the inspired air – Nasal conchae – folds in the mucous membrane that increase air turbulence and

ensures that most air contacts the mucous membranes – Olfactory mucosa – mucous membranes that contain smell receptors – Respiratory mucosa – pseudostratified ciliated columnar epithelium containing

goblet cells that secrete mucus » Mucus » Stickiness traps inhaled particles » Lysozyme kills bacteria

– Lymphocytes and IgA antibodies protect against bacteria

Respiratory Mucosa

Upper Respiratory

Paranasal Sinuses

PharynxThree regions of the pharynx

•Nasopharynx – air passage (pseudostratified columnar epithelium)

•Oropharynx – passageway for air, food, and drink (stratified squamous epithelium)

•Laryngopharynx – passageway for air, food, and drink (stratified squamous epithelium)

LarynxFunctions

1. Keeps food and drink out of the airway 2. Sound production 3. Acts as a sphincter during abdominal straining (ex. during defecation and heavy lifting)

LarynxSelected anatomical features

•Nine c-rings of hyaline cartilage form the framework of the larynx •Muscular walls aid in voice production and the swallowing reflex •Glottis – the superior opening of the larynx •Epiglottis – prevents food and drink from entering airway when swallowing •False vocal cords – aid in closing the glottis when swallowing •True vocal cords – produce sound when air passes between them •The shorter and thinner these membranes are, the faster air moves over them – produces high pitched sounds •The longer and thicker these membranes are, the slower air moves over them – produces low pitched sounds

Glottis

Trachea

• Functions1. Air passageway 2. Cleans, warms, and moistens incoming air

3. Selected anatomical features • Rings of hyaline cartilage – reinforce the trachea

and keep it from collapsing when you inhale• Ciliated pseudostratified epithelium – traps

inhaled debris and propels mucus up to the

pharynx where it is swallowed

Lung Anatomy

•Function - Solely an air passageway •Selected anatomical features

1. Left and right primary bronchi branch off from trachea 2. Once the left and right primary bronchi enter the lungs they are subdivided into smaller tubes:

Secondary bronchi (one for each lobe) → tertiary bronchi → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveolar sacs

3. Alveolar sacs are clusters of alveoli 4. Alveoli are the site of gas exchange 5. Other tissue types present in the alveoli a. Smooth muscle rings aid in resistance to air flow b. Elastic connective tissue fibers aid in expelling

air from the lungs

Anatomy of Bronchi

Lung bronchiogram

Pulmonary arteriogram

Respiratory Physiology

Diaphragm contracts - increase thoracic cavity vl -Pressure decreases - causes air to rush into lungs

Diaphragm relaxes - decrease thoracic cavity vl -Pressure increases – forces air out of lungs

Inspiration

Expiration

Patterns of Breathing

• Apnea – temporary cessation of breathing (one or more skipped breaths)

• Dyspnea – labored, gasping breathing; shortness of breath

• Eupnea – Normal, relaxed, quiet breathing

• Hyperpnea – increased rate and depth of breathing in response to exercise, pain, or other conditions

• Hyperventilation – increased pulmonary ventilation in excess of metabolic demand

• Hypoventilation – reduced pulmonary ventilation

• Orthopnea – Dyspnea that occurs when a person is lying down

• Respiratory arrest – permanent cessation of breathing

• Tachypnea – accelerated respiration

Clinical Disorders and Diseases of the Respiratory System

• Hypoxia – deficiency of oxygen in a tissue or the inability to use oxygen• • Oxygen toxicity – excess oxygen, causing the build up of peroxides and free radicals• • Chronic obstructive pulmonary diseases (COPD) – long-term obstruction of airflow and a substantial reduction in

pulmonary ventilation

• Chronic bronchitis – cilia are immobilized and reduced in number; goblet cells increase their production of mucus → mucus clogs the airways and breeds infection

• Emphysema – alveolar walls break down and the surface area of the lungs is reduced

• Asthma – allergens trigger the release of histamine and other inflammatory chemicals that cause intense bronchoconstriction. In asthma, periodic constriction of the bronchi and bronchioles makes it more difficult to breathe in and, especially, out. Attacks of asthma can be triggered by airborne irritants such as chemical fumes and cigarette smoke airborne particles to which the patient is allergic.

• Lung cancer –most common cancer and most common cause of cancer deaths in U.S. males. There are several forms of lung cancer, but the most common (and most rapidly increasing) types are those involving the epithelial cells lining the bronchi and bronchioles. Ordinarily, the lining of these airways consists of two layers of cells. Chronic exposure to irritants causes the number of layers to increase. The ciliated and mucus-secreting cells disappear and are replaced by a disorganized mass of cells with abnormal nuclei. If the process continues, the growing mass penetrates the underlying basement membrane. Malignant cells can break away and be carried in lymph and blood to other parts of the body where they may lodge and continue to proliferate. It is this metastasis of the primary tumor that eventually kills the patient.

• Acute rhinitis – the common cold• • Laryngitis – inflammation of the vocal folds

• Pneumonia – lower respiratory infection of the alveoli that causes fluid build up in the lungs. It can be caused by many kinds of both bacteria (Streptococcus pneumoniae) and viruses. Tissue fluids accumulate in the alveoli reducing the surface area exposed to air. If enough alveoli are affected, the patient may need supplemental oxygen.

• Sleep apnea – Cessation of breathing for 10 seconds or longer during sleep

• Tuberculosis – pulmonary infection with Mycobacterium tuberculosis; reduces lung compliance

• Pleuritis - Inflammation of the pleura, producing more than the normal amount of fluid, causing a pleural effusion. The pain fibers of the lung are located in the pleura. When this tissue becomes inflamed, it results in a sharp pain in the chest that is worse with breathing in. Other symptoms of pleurisy can include cough, chest tenderness, and shortness of breath.

• Cystic fibrosis - caused by inheriting two defective CFTR genes, a transmembrane protein needed for the transport of Cl− ions out of the epithelial cells of the lung thus enabling water to follow by osmosis. Diminished CFTR function reduces the water content of the fluid in the lungs making it more viscous and difficult for the ciliated cells to move it up out of the lungs. The accumulation of mucus plugs the airways interfering with breathing and causing a persistent cough. Cystic fibrosis is the most common inherited disease in the U.S. white population.

Clinical Disorders and Diseases of the Respiratory System