Chapter 23 The Respiratory System INTRODUCTION. Lecture Outline

Transcription

1 Principles of Human Anatomy and Physiology, 11e 1 Chapter 23 The Respiratory System Lecture Outline INTRODUCTION The two systems that cooperate to supply O 2 and eliminate CO 2 are the cardiovascular and the respiratory system. The respiratory system provides for gas exchange. The cardiovascular system transports the respiratory gases. Failure of either system has the same effect on the body: disruption of homeostasis and rapid death of cells from oxygen starvation and buildup of waste products. Respiration is the exchange of gases between the atmosphere, blood, and cells. It takes place in three basic steps: ventilation (breathing), external (pulmonary) respiration, and internal (tissue) respiration. Principles of Human Anatomy and Physiology, 11e 2 Chapter 23 The Respiratory System Cells continually use O2 & release CO2 Respiratory system designed for gas exchange Cardiovascular system transports gases in blood Failure of either system rapid cell death from O2 starvation Principles of Human Anatomy and Physiology, 11e 3

2 Principles of Human Anatomy and Physiology, 11e 4 Respiratory System Anatomy (Figure 23.1). Nose Pharynx = throat Larynx = voicebox Trachea = windpipe Bronchi = airways Lungs Locations of infections upper respiratory tract is above vocal cords lower respiratory tract is below vocal cords The conducting system consists of a series of cavities and tubes - nose, pharynx, larynx, trachea, bronchi, bronchiole, and terminal bronchioles - that conduct air into the lungs. The respiratory portion consists of the area where gas exchange occurs - respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. Internal Anatomy The interior structures of the nose are specialized for warming, moistening, and filtering incoming air; receiving olfactory stimuli; and serving as large, hollow resonating chambers to modify speech sounds. The internal portion communicates with the paranasal sinuses and nasopharynx through the internal nares. The inside of both the external and internal nose is called the nasal cavity. It is divided into right and left sides by the nasal septum. The anterior portion of the cavity is called the vestibule (Figure 7.14a). The surface anatomy of the nose is shown in Figure Nasal polyps are outgrowths of the mucous membranes which are usually found around the openings of the paranasal sinuses. Principles of Human Anatomy and Physiology, 11e 5 Nose -- Internal Structures Large chamber within the skull Roof is made up of ethmoid and floor is hard palate Internal nares (choanae) are openings to pharynx Nasal septum is composed of bone & cartilage Bony swelling or conchae on lateral walls 6

3 Principles of Human Anatomy and Physiology, 11e 7 Functions of the Nasal Structures Olfactory epithelium for sense of smell Pseudostratified ciliated columnar with goblet cells lines nasal cavity warms air due to high vascularity mucous moistens air & traps dust cilia move mucous towards pharynx Paranasal sinuses open into nasal cavity found in ethmoid, sphenoid, frontal & maxillary lighten skull & resonate voice Rhinoplasty Rhinoplasty ( nose job ) is a surgical procedure in which the structure of the external nose is altered for cosmetic or functional reasons (fracture or septal repair) Procedure local and general anesthetic nasal cartilage is reshaped through nostrils bones fractured and repositioned internal packing & splint while healing Principles of Human Anatomy and Physiology, 11e 8 Pharynx - Overview The pharynx (throat) is a muscular tube lined by a mucous membrane (Figure 23.4). The anatomic regions are the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx functions in respiration. Both the oropharynx and laryngopharynx function in digestion and in respiration (serving as a passageway for both air and food). Principles of Human Anatomy and Physiology, 11e 9

4 Principles of Human Anatomy and Physiology, 11e 10 Pharynx Pharynx Muscular tube (5 inch long) hanging from skull skeletal muscle & mucous membrane Extends from internal nares to cricoid cartilage Functions passageway for food and air resonating chamber for speech production tonsil (lymphatic tissue) in the walls protects entryway into body Distinct regions -- nasopharynx, oropharynx and laryngopharynx Principles of Human Anatomy and Physiology, 11e 11 Larynx - Overview The larynx (voice box) is a passageway that connects the pharynx with the trachea. It contains the thyroid cartilage (Adam s apple); the epiglottis, which prevents food from entering the larynx; the cricoid cartilage, which connects the larynx and trachea; and the paired arytenoid, corniculate, and cuneiform cartilages (Figure 23.5). Voice Production The larynx contains vocal folds (true vocal cords), which produce sound. Taunt vocal folds produce high pitches, and relaxed vocal folds produce low pitches (Figure 23.6). Other structures modify the sound. Principles of Human Anatomy and Physiology, 11e 12

5 Principles of Human Anatomy and Physiology, 11e 13 Cartilages of the Larynx Thyroid cartilage forms Adam s apple Epiglottis---leaf-shaped piece of elastic cartilage during swallowing, larynx moves upward epiglottis bends to cover glottis Cricoid cartilage---ring of cartilage attached to top of trachea Pair of arytenoid cartilages sit upon cricoid many muscles responsible for their movement partially buried in vocal folds (true vocal cords) Larynx Cartilage & connective tissue tube Anterior to C4 to C6 Constructed of 3 single & 3 paired cartilages Principles of Human Anatomy and Physiology, 11e 14 Vocal Cords False vocal cords (ventricular folds) found above vocal folds (true vocal cords) True vocal cords attach to arytenoid cartilages 15

6 Principles of Human Anatomy and Physiology, 11e 16 The Structures of Voice Production True vocal cord contains both skeletal muscle and an elastic ligament (vocal ligament) When 10 intrinsic muscles of the larynx contract, move cartilages & stretch vocal cord tight When air is pushed past tight ligament, sound is produced (the longer & thicker vocal cord in male produces a lower pitch of sound) The tighter the ligament, the higher the pitch To increase volume of sound, push air harder Movement of Vocal Cords Opening and closing of the vocal folds occurs during breathing and speech Principles of Human Anatomy and Physiology, 11e 17 Speech and Whispering Speech is modified sound made by the larynx. Speech requires pharynx, mouth, nasal cavity & sinuses to resonate that sound Tongue & lips form words Pitch is controlled by tension on vocal folds pulled tight produces higher pitch male vocal folds are thicker & longer so vibrate more slowly producing a lower pitch Whispering is forcing air through almost closed rima glottidis -- oral cavity alone forms speech Principles of Human Anatomy and Physiology, 11e 18

7 Principles of Human Anatomy and Physiology, 11e 19 Application Laryngitis is an inflammation of the larynx that is usually caused by respiratory infection or irritants. Cancer of the larynx is almost exclusively found in smokers. Trachea The trachea (windpipe) extends from the larynx to the primary bronchi (Figure 23.7). It is composed of smooth muscle and C-shaped rings of cartilage and is lined with pseudostratified ciliated columnar epithelium. The cartilage rings keep the airway open. The cilia of the epithelium sweep debris away from the lungs and back to the throat to be swallowed. Principles of Human Anatomy and Physiology, 11e 20 Trachea Size is 5 in long & 1in diameter Extends from larynx to T5 anterior to the esophagus and then splits into bronchi Layers mucosa = pseudostratified columnar with cilia & goblet submucosa = loose connective tissue & seromucous glands hyaline cartilage = 16 to 20 incomplete rings open side facing esophagus contains trachealis m. (smooth) internal ridge on last ring called carina adventitia binds it to other organs Principles of Human Anatomy and Physiology, 11e 21

8 Principles of Human Anatomy and Physiology, 11e 22 Trachea and Bronchial Tree Full extent of airways is visible starting at the larynx and trachea Histology of the Trachea Ciliated pseudostratified columnar epithelium Hyaline cartilage as C-shaped structure closed by trachealis muscle Principles of Human Anatomy and Physiology, 11e 23 Airway Epithelium Ciliated pseudostratified columnar epithelium with goblet cells produce a moving mass of mucus. Principles of Human Anatomy and Physiology, 11e 24

9 Principles of Human Anatomy and Physiology, 11e 25 Tracheostomy and Intubation Reestablishing airflow past an airway obstruction crushing injury to larynx or chest swelling that closes airway vomit or foreign object Tracheostomy is incision in trachea below cricoid cartilage if larynx is obstructed Intubation is passing a tube from mouth or nose through larynx and trachea Bronchi The trachea divides into the right and left pulmonary bronchi (Figure 23.8). The bronchial tree consists of the trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and terminal bronchioles. Walls of bronchi contain rings of cartilage. Walls of bronchioles contain smooth muscle. Principles of Human Anatomy and Physiology, 11e 26 Bronchi and Bronchioles Primary bronchi supply each lung Secondary bronchi supply each lobe of the lungs (3 right + 2 left) Tertiary bronchi supply each bronchopulmonary segment Repeated branchings called bronchioles form a bronchial tree Principles of Human Anatomy and Physiology, 11e 27

10 Principles of Human Anatomy and Physiology, 11e 28 Histology of Bronchial Tree Epithelium changes from pseudostratified ciliated columnar to nonciliated simple cuboidal as pass deeper into lungs Incomplete rings of cartilage replaced by rings of smooth muscle & then connective tissue sympathetic NS & adrenal gland release epinephrine that relaxes smooth muscle & dilates airways asthma attack or allergic reactions constrict distal bronchiole smooth muscle nebulization therapy = inhale mist with chemicals that relax muscle & reduce thickness of mucus Pleural Membranes & Pleural Cavity Visceral pleura covers lungs --- parietal pleura lines ribcage & covers upper surface of diaphragm Pleural cavity is potential space between ribs & lungs Principles of Human Anatomy and Physiology, 11e 29