The Respiratory System

24 The Respiratory System

PowerPoint® Lecture Presentations prepared by Steven Bassett Southeast Community College Lincoln, Nebraska

• The respiratory system includes: • Nose • Nasal cavity • Sinuses • Pharynx • Larynx • Trachea • Bronchi • Bronchioles • Alveoli

•The upper respiratory system •Consists of: •Nose, nasal cavity, sinuses, and pharynx •The lower respiratory system •Consists of: •Larynx, trachea, bronchi, bronchioles, and alveoli

Frontal sinus Nasal cavity

Sphenoidal sinus Nasal conchae Nose Internal nares

Nasopharynx Tongue

UPPER RESPIRATORY Hyoid bone SYSTEM Larynx LOWER Esophagus RESPIRATORY Trachea SYSTEM Bronchus

Clavicle

Bronchioles

RIGHT LEFT LUNG LUNG

Ribs Diaphragm

• Functions of the Respiratory System • The following is a partial list of respiratory functions • Provides an area for gas exchange between the air and the blood • Protects the respiratory surfaces from dehydration (for example) • Provides protection against invading pathogens • Produces sound involved in verbal communication • Assists in the regulation of blood volume, blood pressure, and body fluid pH

• The Respiratory Epithelium • Consists of: • Pseudostratified, ciliated, columnar cells (except for the pharynx, smaller bronchi, and alveoli) • Mucus-producing cells • Pharynx consists of stratified squamous cells

• The Respiratory Epithelium • Function • Ciliated columnar cells move mucus in an upward manner (mucus escalator) so debris can be coughed out • Mucous cells produce mucus so inhaled debris will get stuck and not enter the lungs • Stratified squamous cells provide protection against abrasion

• Protection of the Respiratory System • Hairs in the nose block some of the inhaled debris • Called vibrissae • Nasal cavity produces mucus to trap inhaled debris • Sneezing will remove this debris • Respiratory epithelium mucus will trap inhaled debris • Coughing will remove this debris

• The following is the pathway of air: • Air enters the external nares • Passes by the nasal vestibule • Area surrounded by the two pairs of alar cartilage • Enters the nasal cavity • Air flows in and around the nasal conchae • Inferior, middle, and superior conchae • As air swirls around the conchae, debris gets stuck in the mucus • As air swirls around the conchae, the air warms a bit before entering the trachea

• The following is the pathway of air (continued): • Air enters the internal nares • Air enters the nasopharynx area

Frontal sinus

Nasal cavity Superior

Middle Nasal Internal nares conchae Inferior Nasopharynx Nasal vestibule Pharyngeal tonsil External nares Entrance to auditory tube Hard palate Soft palate

Palatine tonsil Oral cavity

Oropharynx Tongue Epiglottis Mandible

Aryepiglottic Lingual tonsil fold

Laryngopharynx Hyoid bone

Glottis Thyroid cartilage Cricoid cartilage Vocal fold Trachea Esophagus Thyroid gland

A sagittal section of the head and neck

• The Pharynx • The pharynx is a passageway that connects the nose to the mouth to the throat • Nasopharynx (the back of the nose area) • Oropharynx (the back of the mouth area) • Laryngopharynx (the area that has the entrance to the trachea and esophagus)

Frontal sinus

Nasal cavity Superior

Middle Nasal Internal nares conchae Inferior Nasopharynx Nasal vestibule Pharyngeal tonsil External nares Entrance to auditory tube Hard palate Soft palate

Palatine tonsil Oral cavity

Oropharynx Tongue Epiglottis Mandible

Aryepiglottic Lingual tonsil fold

Laryngopharynx Hyoid bone

Glottis Thyroid cartilage Cricoid cartilage Vocal fold Trachea Esophagus Thyroid gland

A sagittal section of the head and neck

• The Larynx • A cylinder whose cartilaginous walls are stabilized by ligaments or skeletal muscles or both

• Begins at the level of vertebrae C4 or C5

• Ends at the level of vertebra C7

• Cartilages of the Larynx • Thyroid cartilage • Contains the laryngeal prominence • Cricoid cartilage • Epiglottis • Closes over the glottis during swallowing of food • Paired laryngeal cartilages • Some play a role in the opening and closing of the glottis

Frontal sinus

Nasal cavity Superior

Middle Nasal Internal nares conchae Inferior Nasopharynx Nasal vestibule Pharyngeal tonsil External nares Entrance to auditory tube Hard palate Soft palate

Palatine tonsil Oral cavity

Oropharynx Tongue Epiglottis Mandible

Aryepiglottic Lingual tonsil fold

Laryngopharynx Hyoid bone

Glottis Thyroid cartilage Cricoid cartilage Vocal fold Trachea Esophagus Thyroid gland

A sagittal section of the head and neck

Lesser cornu

Hyoid bone

Thyrohyoid ligament (extrinsic)

Laryngeal prominence Thyroid Larynx cartilage

Cricothyroid ligament (intrinsic) Cricoid cartilage

Cricotracheal ligament (extrinsic)

Trachea Tracheal cartilages

Epiglottis

Vestibular ligament Thyroid Vocal cartilage ligament

Arytenoid cartilage

Cricoid cartilage

Tracheal cartilages

• Laryngeal Ligaments • A series of intrinsic laryngeal ligaments bind the laryngeal cartilages together • Extrinsic laryngeal ligaments bind the thyroid cartilage to the hyoid bone and cricoid cartilage • Some of the ligaments become the vocal cords

• Sound Production by the Vocal Cords • Air passing between the vocal cords creates sound • Pitch depends on the diameter, length, and tension in the vocal cords • Children have slender, short vocal folds thus creating a high-pitched sound • At puberty, the vocal cords of males become thicker and longer thus producing a deeper voice than females • Amplification of sound occurs in the sinus cavities • Production of definite sounds depends on movement of the lips, tongue, and cheeks

Corniculate POSTERIOR cartilage Corniculate cartilage Glottis (closed) Cuneiform Glottis (open) cartilage Aryepiglottic Vestibular fold fold

Vocal fold Vocal fold

Vestibular fold Epiglottis

Root of tongue Epiglottis ANTERIOR

Glottis in the open Glottis in the closed position position

POSTERIOR

POSTERIOR Corniculate cartilage Glottis (closed)

Glottis (open) Cuneiform cartilage in aryepiglottic fold

Vocal fold

Vestibular fold

Epiglottis

ANTERIOR Root of tongue

Glottis in the closed position ANTERIOR

This photograph is a representative laryngoscopic view. For this view the camera is positioned within the oropharynx, just superior to the larynx.

• Laryngeal Musculature • Intrinsic muscles • Regulate tension of the vocal cords • Open and close the glottis • Extrinsic muscles • Position and stabilize the larynx

Tongue forces Hard palate compacted bolus Soft palate into oropharynx. Tongue Bolus

Epiglottis

Larynx Trachea

Laryngeal movement folds epiglottis; Soft palate pharyngeal muscles push bolus into esophagus. Bolus Epiglottis

Bolus moves along esophagus; larynx returns to normal position.

Epiglottis

• Characteristics of the Trachea • About 2.5 cm in diameter • Contains tracheal cartilage • Each cartilage ring is actually C-shaped, not a complete ring • Connecting one cartilage ring to another are annular ligaments • The lining consists of: • Respiratory epithelia • Lamina propria • Submucosa

Larynx

Annular ligaments

Trachea

Tracheal cartilages

Location of carina Root of (internal ridge) right lung Root of Superior left lung lobar bronchus

Lung Primary tissue bronchi Superior lobar bronchus Middle lobar Secondary bronchus bronchi Inferior lobar bronchi

RIGHT LUNG LEFT LUNG

• Characteristics of the Trachea (continued) • The posterior side of the cartilage ring is the trachealis muscle • This muscle allows for constriction and dilation of the trachea • The trachea branches at the carina to form the left and right bronchi

Larynx

Annular ligaments

Trachea

Tracheal cartilages

Location of carina Root of (internal ridge) right lung Root of Superior left lung lobar bronchus

Lung Primary tissue bronchi Superior lobar bronchus Middle lobar Secondary bronchus bronchi Inferior lobar bronchi

RIGHT LUNG LEFT LUNG

Esophagus

Trachealis muscle

Lumen of trachea Thyroid gland

Respiratory epithelium

Tracheal cartilage

The trachea LM  3

• The left and right primary bronchi branch off the trachea at the area of the carina • The primary bronchi enter into each lung • The right primary bronchus is steeper and larger in diameter than the left • Hence, children can aspirate foreign objects into the right lung easier than the left lung

• Each primary bronchus will enter the lung at the point called the hilum • The hilum is also the point of entrance and exit of the pulmonary blood vessels • The combination of the bronchus, artery, and vein is called the root

Frontal sinus Nasal cavity

Sphenoidal sinus Nasal conchae Nose Internal nares

Nasopharynx Tongue

UPPER RESPIRATORY Hyoid bone SYSTEM Larynx LOWER Esophagus RESPIRATORY Trachea SYSTEM Bronchus

Clavicle

Bronchioles

RIGHT LEFT LUNG LUNG

Ribs Diaphragm

• Structure of the Lungs • The apex points superiorly and the base inferiorly • The right lung has three lobes • Superior, middle, and inferior lobes • Consists of a horizontal fissure and an oblique fissure • The left lung has two lobes • Superior and inferior lobes • Contains the oblique fissure • Left lung has a cardiac notch

Boundary between right and left Superior lobe pleural cavities

LEFT LUNG RIGHT LUNG

Superior lobe

Horizontal fissure Oblique fissure

Middle lobe Fibrous layer Oblique fissure of pericardium Inferior lobe Inferior lobe Falciform ligament

Cut edge of diaphragm Anterior view of the opened chest, Liver, Liver, showing the relative positions of right lobe left lobe the left and right lungs and heart.

Lateral Surfaces

Diagrammatic views of Apex Apex the lateral surfaces of the isolated right and Superior lobe left lungs Superior lobe

Horizontal fissure Middle lobe Inferior Cardiac lobe notch Inferior Oblique Oblique lobe fissure fissure

Base Base RIGHT LUNG LEFT LUNG

Medial Surfaces

Apex Diagrammatic views of the medial surfaces of Superior lobar bronchus Superior Superior the isolated right and lobe Pulmonary arteries lobe left lungs Middle lobar bronchus Groove for aorta Superior lobar bronchus

Pulmonary Pulmonary veins Inferior lobar bronchus veins Horizontal Cardiac fissure Middle Hilum impression lobe Inferior Inferior Oblique lobe Oblique lobe fissure fissure

Groove for Diaphragmatic esophagus Base surface

RIGHT LUNG LEFT LUNG

• Structure of the Pulmonary Bronchi • The primary bronchi branch numerous times once inside the lungs (outside the lungs they are called extrapulmonary bronchi while inside the lungs they are called intrapulmonary bronchi) • Each primary bronchus divides to form: • Secondary bronchi and tertiary bronchi • Each tertiary bronchus goes to a specific lung area called a bronchopulmonary segment

• Detailed Branching of the Primary Bronchi • The right lung has 10 tertiary bronchi and therefore 10 bronchopulmonary segments • The left lung has 8 or 9 segments • The trachea and primary bronchi have rings of cartilage • The secondary and tertiary have cartilage plates • The final branch (bronchiole) does not have any cartilage

Apicoposterior Apical Bronchopulmonary Posterior Anterior segments of Anterior Bronchopulmonary superior lobe Superior lingular segments of superior lobe Medial Inferior lingular Bronchopulmonary segments of Lateral middle lobe Superior Superior Medial basal Lateral basal Posterior basal Bronchopulmonary Medial segments of Bronchopulmonary basal Anterior basal inferior lobe segments of inferior lobe Posterior basal Lateral basal Anterior basal Right lung, costal surface Left lung, costal surface

Isolated left and right lungs have been colored to show the distribution of the bronchopulmonary segments.

LEFT LUNG Primary bronchus

Cartilage ring Secondary (superior lobar) bronchus Root of lung

Secondary (inferior lobar) bronchus

Cartilage plates

Visceral pleura

BRONCHIOLE Tertiary bronchi Respiratory epithelium

Smooth muscle

Bronchioles

• The Bronchioles • Tertiary bronchi give rise to bronchioles • Bronchioles have a diameter of 0.3–0.5 mm • They are self-supporting and therefore do not require cartilage plates • Consist of smooth muscle for bronchodilation (sympathetic stimulation) and bronchoconstriction (parasympathetic stimulation) • Bronchioles terminate with clusters of alveolar sacs

Trachea Respiratory epithelium Branch of pulmonary Bronchiole artery

Left Bronchial artery (red), primary vein (blue), and nerve (yellow) bronchus Smooth muscle around terminal Visceral bronchiole pleura Secondary Terminal bronchus bronchiole Tertiary bronchi Respiratory bronchiole

Elastic fibers Smaller bronchi Capillary Arteriole Branch of beds Lymphatic pulmonary Bronchioles vessel vein Alveolar Terminal bronchiole duct Respiratory bronchiole Alveoli Alveoli in a pulmonary lobule

Bronchopulmonary segment Alveolar sac

Interlobular septum

Visceral pleura

Pleural cavity Parietal pleura

The structure of one portion of a single pulmonary lobule

• Alveolar Ducts and Alveoli • Each lung has about 150 million alveoli • Extensive network of capillaries surround each alveolus • Capillaries drop off carbon dioxide and pick up oxygen • Elastic tissue surrounds each alveolus • Maintains the shape and position of each alveolus during inhalation and exhalation

Respiratory bronchiole Smooth muscle Alveolar duct

Alveolus Elastic fibers Alveolar sac

Capillaries

Basic structure of a lobule, cut to reveal the arrangement between the alveolar ducts and alveoli. A network of capillaries surrounds each alveolus. These capillaries are surrounded by elastic fibers. © 2012 Pearson Education, Inc. The Lungs

• Alveoli Details • The cells associated with alveoli • The lining consists of a single layer of squamous cells • These are called type I pneumocytes • Type II pneumocytes are scattered among the type I pneumocytes • Type II pneumocytes secrete surfactant • Surfactant prevents alveolar collapse • Alveolar macrophages wander around phagocytizing particulate matter

Alveoli

Alveolar sac

Alveolar duct Lung tissue LM  125

SEM of lung tissue showing the appearance and organization of the alveoli

Pneumocyte Pneumocyte type II cell type I cell

Alveolar macrophage

Elastic fibers

Alveolar macrophage

Capillary

Endothelial cell of capillary

• Gas Exchange at the Alveoli • Pulmonary arteries transport carbon dioxide to the alveolar capillaries • Carbon dioxide leaves the capillaries and enters the alveolar sacs • Oxygen leaves the alveolar sacs and enters the capillaries • Oxygen enters the pulmonary veins and returns to the heart to be pumped to all parts of the body

Pneumocyte Pneumocyte type II cell type I cell

Alveolar macrophage Red blood cell Elastic fibers Nucleus of Capillary lumen endothelial cell Endothelium

0.5  m Alveolar macrophage

Capillary Fused Alveolar Surfactant basal epithelium laminae Endothelial cell of Alveolar air space capillary

Diagrammatic sectional view of alveolar structure The respiratory membrane and the respiratory membrane

Trachea Respiratory epithelium Branch of pulmonary Bronchiole artery

Bronchopulmonary segment Alveolar sac

Interlobular septum

Visceral pleura

Pleural cavity Parietal pleura

The structure of one portion of a single pulmonary lobule

• The right and left pleural cavities are separated by the mediastinum • Each lung is lined by a serous membrane • The membrane is made of two continuous layers • Visceral pleura portion covers the outer surface of the lung • Parietal pleura portion covers the inside lining of the thoracic wall • The space created between the visceral and parietal is the pleural cavity

• The pleural cavity between the visceral and parietal membranes consists of: • Pleural fluid • Reduces friction when the lungs move upon inhalation and exhalation • Pleurisy • A condition in which the membranes produce too much pleural fluid or the membranes adhere to the thoracic wall thereby resulting in pain upon inhalation and exhalation

Pericardial cavity Body of sternum Right lung, Ventricles middle lobe

Oblique fissure Rib Left lung, Right pleural superior lobe cavity Visceral pleura Atria Left pleural cavity Esophagus Parietal pleura Aorta Bronchi Right lung, inferior lobe Left lung, inferior lobe Spinal cord Posterior mediastinum

• Respiratory Muscles • The muscles involved in pulmonary ventilation (breathing) are: • Diaphragm • External intercostals • Internal intercostals

• Diaphragm • Contracts (lowers) to cause inhalation • Relaxes (raises) to cause exhalation • External intercostals • Elevate the ribs to aid in inhalation • Internal intercostals • Depress the ribs to aid in exhalation

Ribs and sternum elevate

Diaphragm contracts

As the ribs are elevated or the diaphragm is depressed, the volume of the thoracic cavity increases and air moves into the lungs. The outward movement of the ribs as they are elevated resembles the outward swing of a raised bucket handle. © 2012 Pearson Education, Inc. Figure 24.16b Respiratory Muscles Accessory Muscles of Inspiration External intercostal muscles Sternocleidomastoid muscle Scalene muscles Accessory Muscles of Exhalation

Pectoralis Internal intercostal minor muscle muscles

Serratus Transversus thoracis anterior muscle muscle

External oblique Diaphragm muscle

Rectus abdominus

Internal oblique muscle The primary and accessory muscles of respiration

Scalene Sternocleidomastoid muscles muscle

Pectoralis minor muscle

Serratus anterior muscle

External intercostal muscles Diaphragm

Transversus thoracis muscle

Internal intercostal muscles

Rectus abdominis and other abdominal muscles (not shown)

• Respiratory Movements • Respiratory movements can be classified two ways: eupnea or hyperpnea • Eupnea: quiet breathing • May involve diaphragmatic breathing or costal breathing or both • During pregnancy, due to the uterus pushing upward on the diaphragm, women typically use costal breathing • Hyperpnea: forced breathing • Generally requires the use of accessory breathing muscles © 2012 Pearson Education, Inc. Figure 24.16b Respiratory Muscles Accessory Muscles of Inspiration External intercostal muscles Sternocleidomastoid muscle Scalene muscles Accessory Muscles of Exhalation

Pectoralis Internal intercostal minor muscle muscles

Serratus Transversus thoracis anterior muscle muscle

External oblique Diaphragm muscle

Rectus abdominus

Internal oblique muscle The primary and accessory muscles of respiration

• Respiratory Centers of the Brain • There are three pairs of nuclei in the pons and medulla oblongata that regulate the respiratory muscles • The respiratory rhythmicity center sets the respiratory pace • The apneustic center adjusts the respiratory pace • The pneumotaxic center adjusts the respiratory pace

Cerebrum

HIGHER CENTERS Cerebral cortex Limbic system Hypothalamus

Pons CSF CHEMORECEPTORS Pneumotaxic center Apneustic center Medulla N IX and N X oblongata

Chemoreceptors and baroreceptors of carotid and aortic sinuses N X Dorsal Stretch respiratory receptors group (DRG) of lungs Diaphragm Respiratory Ventral rhythmicity Spinal respiratory centers cord group (VRG)

Motor neurons controlling diaphragm

Motor neurons controlling other respiratory muscles

• There are three different reflexes involved in respiration: • Mechanoreceptor reflexes • Respond to changes in lung volume or changes in blood pressure • Chemoreceptor reflexes • Respond to changes in partial pressures of carbon dioxide and oxygen • Respond to changes in pH • Protective reflexes • Respond to physical injury or irritation

• The respiratory system becomes less efficient as we age. • Noteworthy changes include: • Elastic tissue begins to deteriorate • Lungs cannot expand or constrict as much as they used to • Movements of the ribs are restricted due to arthritis • Some degree of emphysema, which hinders breathing • With age, roughly one square foot of respiratory membrane is lost each year after age 30 © 2012 Pearson Education, Inc.