Respiratory System Chapter 21
Structural Anatomy Upper respiratory system Lower respiratory system throat windpipe voice box
Function of Respiratory System Gas exchange Contains receptors for sense of smell Filters and warms inspired air Produces sound Eliminates waste
Gas Exchange Intake of O 2 and elimination of CO 2. Cardiovascular involvement? 4 steps in respiration (atmosphere blood cells) Pulmonary ventilation breathing, inspiration/expiration of air. External (pulmonary) respiration exchange of gases between air space of lungs and blood in pulmonary capillaries. Transport of respiratory gases transport of gases between the lungs and body tissues by cardiovascular system. Internal (tissue) respiration exchange of gasses between blood in systemic capillaries and tissue cells.
Functional Anatomy Conducting portion hard tubes, interconnecting cavities and rigid tubes that lead to the sites of gas exchange in microscopic lung tissue. Nose, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles, all serve to conduct air into lungs. Respiratory portion soft spaces, consists of those portions where the exchange of gasses occurs. Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, most of lung volume.
The Nose Provides: air passage moistens and warms air filters air resonating chamber for sound houses olfactory (smell) receptors.
The Nose (external and internal portion) External nares openings Nasal bones Skeletal framework provided by nasal and maxillary bones Nasal cartilage Flexible plates of hyaline cartilage Lateral, septal, and alar cartilages
The Nose (internal portion)
The Nose (internal portion) Nasal cavity space inside the internal nose, divided into halves by a vertical petition (septum). Septum formed by hyaline cartilage, vomer and perpendicular plate. Nasal conchae subdivide the cavity into a series of groovelike passages (meatus) line w/ mucous membranes.
Mucous membranes contain capillaries and epithelial tissue w/ goblet cells.
Olfactory Receptors Olfactory receptors lie in the superior portion of the nasal cavity, olfactory epithelium. Olfactory nerve communicates with these recepotrs through the cribiform plate of the ethmoid bone.
Paranasal Sinuses Air filled spaces lined w/ respiratory mucosa, located w/in skull bones.
Paranasal Sinuses These spaces open into the nasal cavity and are lined with mucous membranes, and can drain secretions into the nasal cavity. Inflammation and swelling may cause pressure (sinus headache). Resonators of the voice sounds.
Pharanyx (Throat) Passage for: 1) food from oral cavity to esophagus and 2) air passing between nasal cavity and oral cavity to the larynx.
Pharanyx (Throat) 3 parts: 1) nasopharynx swallowing causes uvula and soft palate to move superiorly to block food from entering this area.
Nasopharynx Openings in the nasopharnyx Pharyngotympanic tubes (auditory tube), drains the middle ear. Pharyngeal tonsils (adenoids)
Oropharynx Oropharynx intermediate portion of pharynx. Serves as both passage for air and food. Palatine tonsil pair of tonsils located in faucal wall. Lingual tonsil covers posterior base of tongue.
Laryngopharnyx Connects esophagus (food tube) with the larynx (voice box), where the food and airway passage diverge. It is both a respiratory and digestive pathway. During swallowing, the food has the right of way and air passage is blocked by the epiglotis in larynx.
Functions: The Larynx Airway, routes food and air to proper channel. Voice production, voice box.
The Larynx The walls are made up of 9 pieces of cartilage.
The Larynx 1 thyroid cartilage prominence (Adam s apple). Thyroid gland sits on this triangular piece. Hyoid bone attached to it via ligaments. 1 cricoid cartilage ring of hyaline cartilage. Landmark for tracheostomy.
The Larynx 1 epiglottis cartilage acts as trap door over the glottis. During swallowing, the larynx rises causing the apparatus to move down to block liquids and food en route to esophagus.
The Larynx 2 arytenoid cartilage anchors the vocal chords. 2 corniculate & 2 cuneiform help in support of vocal folds and lateral aspects of layrnx.
Voice Production Vocal cords are elastic and when air is directed against them they vibrate. Pitch is controlled by the tension of the cords, provided by laryngeal muscles. Loudness depends on the force of the air across the folds. Inflammation of the cords can cause laryngitis. Upper respiratory pathway (pharynx & nasal) responsible for forming recognizable sounds with help of the paranasal sinuses and muscles in throat and face help in enunciation of words.
Tubular passageway located anterior to esophagus, from the larynx down into the thoracic cavity where it splits into 2 bronchi. Tracheal cartilage 16-20 C shaped hyaline cartilage rings. Trachea
Opening of cartilage ring pointed posteriorly which allows for expansion of esophagus as food passes through. Rings also keep the trachea from collapsing and blocking the airway.
Bronchi and Subdivisions: Bronchial Tree A branched airway that leads from the trachea to the microscopic air sacs in lungs. Primary, Secondary and Tertiary Bronchi.
Bronchi and Subdivisions: Bronchial Tree Primary Bronchi trachea divide into left and right primary bronchi and then enters lung at medial hilus.
Bronchi and Subdivisions: Bronchial Tree Secondary (lobar) bronchi primary bronchi divide into secondary bronchi. Bronchi undergo successive divisions to create the bronchial tree, about 23 in all.
Bronchi and Subdivisions: Bronchial Tree Tertiary (segmental) bronchi supplies a portion of the lung called the bronchopulmonary segment.
Right lung (largest) is divided into 3 lobes upper, middle, and inferior. Left lung divided into 2 lobes upper and lower.
Bronchopulmonary Segments Each lobe is separated by C.T. into segments with tertiary bronchi, veins, and arteries.
Bronchi and Subdivisions: Bronchial Tree Bronchiole branches of the segmental bronchi under 1 mm in diameter that enter the lobes of the lungs. Terminal bronchiole branches from bronchiole under 0.5 mm. This is where the respiratory system begins!
Respiratory Bronchiole Respiratory bronchiole 2 or more branches from each terminal bronchiole with air sac buds. This is the first level of air exchange.
Alveoli are covered in cobweb of pulmonary capillaries. Comprises some 70-80 sq. meters. Gas exchange is by diffusion through these respiratory membranes.
Alveoli are lined with simple squamos epithelium (Type I) which aid in gas exchange. Type II, cuboidal epithelial cells are present and secrete surfactant to prevent alveoli from sticking together.
Tissue Composition Changes in the Respiratory Tree As branching becomes more extensive in the bronchial tree there are structural changes.epithelia, cartilage and smooth muscle changes. Epithelia changes epithelium changes from psuedostratified ciliated columnar in bronchi to nonciliated simple cuboidal cells in the terminal bronchioloes. (macrophages clear debris at this level) Cartilage changes incomplete cartilage rings in primary bronchi give way to cartilage plates which finally disappear in the distal bronchioles.
Tissue Composition Changes in the Respiratory Tree Smooth muscle dominates the respiratory zone as cartilage decreases, the amount of smooth muscle increases. Contraction of these spiral bands of muscle is controlled by the ANS and chemicals (epinephrine relaxes, histamine contracts). Muscle layer persists to the end of the respiratory bronchioles. Excessive contraction can close off airways and create life-threatening event (asthma?)
Lungs and Pleural Cavities Lungs are paired, cone shaped, spongy organs located in the thoracic cavity separated by the heart and mediastinum. They are enclosed by the diaphragm and thoracic cage. The bronchi and blood vessels enter medially through the hilus (depression). Lung tissue is mostly open space with supporting elastic C.T.
Ventilation
Ventilation Muscles of inspiration diaphragm and external intercostals Muscles of forced expiration internal intercostals and abdominal muscles