JC HBHD 2 Week 3 Chapter 17 Respiratory

Respiratory System

• The respiratory system is covered in chapter 17.
• Learning objectives for lesson 17.1 include listing and describing the function of respiratory system organs, discussing the structures and conditions of the upper respiratory tract, and discussing the structures and conditions of the lower respiratory tract.
• The basic plan of the respiratory system is similar to an inverted tree.
• Gas exchange occurs through diffusion.
• The upper respiratory tract includes the nose, pharynx, and larynx.
• The lower respiratory tract includes the trachea, bronchial tree, and lungs.
• Respiratory mucosa lines the air distribution tubes and produces a mucus blanket.
• The cilia on mucosal cells move mucus upward to the pharynx.

Nose

• The nasal septum divides the nose into two cavities.
• The mucous membrane lines the nose.
• Nasal polyps are noncancerous growths.
• Frontal, maxillary, sphenoidal, and ethmoidal sinuses drain into the nose.
• The nose warms and moistens inhaled air.
• Functions of the nose: Warms and moistens inhaled air; contains sense organs of smell.

Pharynx

• The pharynx (throat) is approximately 12.5 cm (5 inches) long and divided into nasopharynx, oropharynx, and laryngopharynx.
• The pharynx has openings for nasal cavities, mouth, esophagus, larynx, and auditory tubes.
• Pharyngeal tonsils and openings to the auditory tubes are in the nasopharynx.
• Other tonsils are in the oropharynx.
• The pharynx is lined by mucous membrane.

Larynx

• The larynx (voice box) is located below the pharynx.
• It has several pieces of cartilage including the thyroid cartilage (Adam's apple).
• The epiglottis partially covers the opening into the larynx.
• The larynx contains a mucous lining and vocal cords.
• The space between the cords is called the glottis.
• Functions of the larynx: Air distribution and voice production.

Laryngeal Cancer

• The incidence increases with age and alcohol abuse.
• Mostly affects men over age 50.
• Removal of the larynx may require esophageal speech or an artificial larynx.

Upper Respiratory Infections (URIs)

• Rhinitis: Nasal inflammation (cold, influenza, or allergies).
• Pharyngitis: Inflammation or infection of the pharynx (sore throat)
• Infectious rhinitis is also known as the common cold.
• Allergic rhinitis is also known as hay fever.

Laryngitis

• Inflammation of the larynx due to infection or irritation.
• Epiglottitis is a life-threatening condition, caused by Haemophilus influenzae type B (Hib) infection.
• Croup causes a barking cough.

Anatomical Conditions

• Deviated septum: A septum that is abnormally far from a midsagittal plane (congenital or acquired).
• Epistaxis (bloody nose): Due to mechanical injuries to the nose, hypertension, or other factors.

Trachea

• The trachea (windpipe) is about 11 cm (4.5 inches) long.
• It extends from the larynx into the thoracic cavity.
• C-shaped rings of cartilage hold the trachea open.
• Function: Passageway for air to move to and from the lungs.
• Obstruction can be life-threatening in minutes.
• Common procedures to clear obstructions include abdominal thrusts and tracheostomies.

Bronchi, Bronchioles, and Alveoli

• The trachea branches into right and left bronchi, with the right bronchus being more vertical.
• Aspirated objects often lodge in the right primary bronchus.
• Each bronchus branches into smaller tubes (secondary bronchi), eventually leading to bronchioles.
• Bronchioles end in clusters of microscopic alveolar sacs.
• Alveolar walls are made up of alveoli, which are where gas exchange occurs between air and blood.

Functions of Bronchi, Bronchioles, and Alveoli

• Bronchi and bronchioles distribute air.
• Alveoli exchange gases between blood and air.
• Type II cells produce surfactant to help reduce surface tension in the alveoli.

Gas Exchange Structures of the Lung

• These structures include alveoli, surfactant, capillaries, and other components essential for gas exchange.
• Alveolar walls provide a large surface area for diffusion.

Respiratory Distress

• Infant respiratory distress syndrome (IRDS) is a leading cause of death in premature infants. It's caused by a lack of surfactant production.
• Adult respiratory distress syndrome (ARDS) is surfactant impairment caused by foreign substances or other factors.

Structure of the Lungs

• Lungs are large enough to fill the chest cavity, except for where the heart and large blood vessels are located.
• The apex is the narrow upper portion of each lung.
• The base is the broader lower part that rests on the diaphragm.

Structure of the Pleura

• The pleura is a moist, smooth, slippery membrane lining the chest cavity. It covers the lungs and chest wall, reducing friction during breathing.

Functions of the Lungs and Pleura

• Function: Pulmonary ventilation (breathing).
• Pleurisy: Inflammation of the pleura.
• Atelectasis: Incomplete expansion or collapse of the lung.
• Pneumothorax: Presence of air in the pleural space.
• Hemothorax: Presence of blood in the pleural space.

Conditions of the Lower Respiratory Tract

• Acute bronchitis.
• Pneumonia.
• Tuberculosis.
• Restrictive pulmonary disorders.
• Obstructive pulmonary disorders (e.g., COPD, chronic bronchitis, emphysema, asthma).
• Lung cancer.

Respiration and Gas Exchange

• Pulmonary ventilation involves inspiration (breathing in) and expiration (breathing out).
• Mechanically this occurs due to changes in pressure and volume of the thorax.
• Mechanisms include the diaphragm and external and internal intercostals.
• Regulation is done by the brainstem, including central regulatory centers.
• Breathing rates are influenced by factors like the medullary rhythmicity area.

Volumes of Air Exchanged in Pulmonary Ventilation

• Tidal volume.
• Inspiratory Reserve Volume.
• Expiratory Reserve Volume.
• Vital Capacity.
• Residual Volume.
• Total Lung Capacity.

Regulation of Ventilation

• Regulation permits body adaptation to varying oxygen and carbon dioxide needs.
• Brainstem’s respiratory control centers respond to changes in chemical levels and other factors.
• Medullary centers set the resting breathing rate.
• Pontine centers adjust the breathing rhythm.
• External factors, like the cerebral cortex, influence, but to a limited extent, respiratory control.

Breathing Patterns

• Eupnea (normal breathing).
• Hyperventilation (rapid, deep breathing).
• Hypoventilation (slow, shallow breathing).
• Dyspnea (labored or difficult breathing).
• Orthopnea (dyspnea relieved by upright posture).
• Apnea (cessation of breathing).
• Cheyne-Stokes Respiration (CSR).

Pulmonary Gas Exchange

• Carbaminohemoglobin: Carbon dioxide bonds to hemoglobin.
• Carbon Dioxide Movement: Carbon dioxide leaves lung blood and enters the alveoli.
• Oxygen Movement: Oxygen moves from alveoli into blood.
• Oxyhemoglobin: Oxygen binds with hemoglobin.

Blood Transportation of Gases

• Oxygen transport: Most oxygen binds to hemoglobin to form oxyhemoglobin.
• Carbon dioxide transport: Significant amounts transported as bicarbonate ions in blood. Some as carbaminohemoglobin. There are additional ways to transport gases in blood, including dissolved forms.