RESPIRATORY SYSTEM

RESPIRATORY SYSTEM


ORGANS OF THE RESPIRATORY SYSTEM

  • Nose

  • Pharynx

  • Larynx

  • Trachea

  • Bronchi

  • Lungs-Alveoli

FUNCTION OF THE RESPIRATORY SYSTEM

  • Oversees gas exchanges between the blood and external environment

  • Exchange of gasses takes place within the lungs in the alveoli

  • Passageways to the lungs purify, warm, and humidify the incoming air

  • What is the demarcation/dividing line of the respiratory system? 

    • Larynx

NOSE

  • The only externally visible part of the respiratory system

  • External nares: nostrils: where air enters the nose 

  • The interior of the nose consists of a nasal cavity divided by a nasal septum

THE UPPER RESPIRATORY TRACT


ANATOMY NASAL CAVITY

  • Olfactory receptors: located in the mucosa on the superior surface

  • Respiratory mucosa: lines the rest of the nasal cavity

    • moistens air

    • traps incoming foreign particles

  • Conchae: projections on the lateral walls

    • increases surface area

    • increases air turbulence within the nasal cavity

  • Palate: separated the nasal cavity from the oral cavity

    • Anterior hard palate (bone)

    • Posterior soft palate (muscle)

  • Epistaxis: nose bleeding

    • Causes:

      • Infections

      • Nose picking

      • Allergies

      • Blood thinners

      • chemical irritants

      • high altitudes

      • more


PARANASAL SINUSES

  • Paranasal sinuses: cavities within bones surrounding the nasal cavity

    • Frontal bone

      • If you have a headache here, you have congested sinuses

    • Sphenoid bone

    • Ethmoid bone

    • Maxillary bone

  • Function of the sinuses

    • Lighten the skill

    • act as resonance chambers for speech

    • produce mucus that drains into the nasal cavity

  • Sinusitis: inflammation of the sinuses

  • Rhinitis: inflammation of the nasal mucosa


PHARYNX (THROAT)

  • Pharynx: The muscular passage from nasal cavity to larynx

    • Innervated by the Glossopharyngeal CN (9)

  • 3 regions

    • Nasopharynx–superior region behind nasal cavity

    • Oropharynx–middle region behind mouth

    • Laryngopharynx–inferior region attached to larynx

  • Oropharynx & laryngopharynx: common passageways for air and food

STRUCTURES OF PHARYNX

  • Auditory tubes enter the nasopharynx

  • Tonsils of the Pharynx

    • are part of the digestive, lymphatic systems (contains lymphoid follicies)

    • Pharyngeal tonsil (adenoids): loc in nasopharynx

    • Palatine tonsils: loc in oropharynx

    • Lingual tonsils: loc at the base of the tongue

  • Otitis Media: throat infection

LARYNX

  • Voice box

  • Routes air and food into proper channels

  • Plays a role in speech

  • Made of 8 rigid hyaline cartilages and an epiglottis  

    • Epiglottis: spoon-shaped flap of elastic cartilage

STRUCTURES OF THE LARYNX

  • Thyroid cartilage

    • Adam’s apple

    • largest hyaline cartilage

    • protrudes anteriorly

  • Epiglottis: superior opening of the larynx

    • routes food to the larynx and air toward the trachea

  • Vocal cords

    • vocal folds

    • vibrate with expelled air to create sound (speech)

    • Glottis: opening between vocal cords

  • What if food goes straight to the trachea? 

    • R. Primary bronchus is shorter and more vertical 

    • Will go to the lungs

    • Lungs do not have enzymes to digest the food

    • Obstructs airflow

    • Causes infection

TRACHEA

  • Windpipe

  • Connects larynx with bronchi

  • Lined with ciliated mucosa

    • Beat continuously in the opposite direction of incoming air

    • expel mucus loaded with dust and other debris away from lungs

  • Walls are reinforced with C-shaped hyaline cartilage

  • Location: 

    • begins in the neck as a continuation of the larynx at the lower border of the cricoid cartilage at the level of C6 

    • It descends in the midline of the neck. 

    • In the thorax, the trachea ends below at the carina by dividing into right and left principal (main) bronchi at the level of the sternal angle (opposite the disc between T4-T5)

  • Landmark: C6- T4/T5

LUNGS

  • occupy most of the thoracic cavity

ANATOMY OF THE LUNGS

  • Apex: is near the clavicle (superior position)

    • Base rests on the diaphragm (inferior portion)

    • projects into the neck

    • convex upward, from the sternoclavicular joint to a point 1 in. (2.5 cm) above the junction of the medial and intermediate thirds of the clavicle

  • Base: concave and fits over the convex area of the diaphragm

  • separated from each other by the heart and other structures of the mediastinum

  • Costal surface: lying against the ribs

  • Mediastinal (medial) surface: contains a region, the hilum

    • hilum: where bronchi, pulmonary blood vessels, lymphatic vessels, and nerves enter and exit

  • Root of the lung: held together by pleura and connective tissue

  • Cardiac notch: where apex of heart lies

  • Left lung: is 10% smaller than the right

  • Right lung: thicker and broader

    • shorter because of the diaphragm

    • higher on the right because it accommodates the liver that lies inferior to it



LOBES AND FISSURES OF THE LUNGS

  • Each lung is divided into lobes by fissures

    • Left lung–2 lobes (heart is more on the left)

    • Right lung–3 lobes


  • Left Lung

    • Lobes

      • upper lobe

      • lower lobe

    • Fissure: oblique fissure

  • Right Lung

    • Lobes:

      • Upper lobe

      • middle lobe: smaller triangular lobe bounded by the horizontal and oblique fissures

      • lower lobe

    • Fissures

      • Oblique fissure: runs from the inferior border upward and backward across the medial and costal surfaces until it cuts the posterior border 2.5 inches below the apex sure:

      • Horizontal fissure: runs horizontally across the costal surface at the level of the 4th costal cartilage to meet the oblique fissure

  • Purpose of the lobes: Each lobe has their own blood supply and drainage

    • If problems spread to the other lobes—> problem is severe


BORDERS OF THE LUNGS

  • Anterior Border of the Lung

    • Right lung:  behind the sternoclavicular joint and runs downward, almost reaching the midline behind the sternal angle continues until the xiphisternal joint

      • turns sharply down to the level of the xiphisternal joint

    • Left lung: at the level of the fourth costal cartilage it deviates laterally and extends for a variable distance beyond the lateral margin of the sternum to form the cardiac notch

      • Cardiac Notch: produced by the heart displacing the lung to the left.

  • Lower Border of the Lung

    • Mid Inspiration: level changes during inspiration and expiration

  • Posterior Border of the Lung

    • cervical vertebra to the level of T10 and lies about 1.5 in. (4 cm) from the midline

  • Oblique Fissure

    • from the root of the spine of the scapula obliquely downward, laterally and anteriorly, following the course of the 6th rib to the sixth costochondral junction.

    • Left lung: the upper lobe lies above and anterior to this line; the lower lobe lies below and posterior to it

  • Horizontal Fissure

    • Right lung

    • along the fourth costal cartilage to meet the oblique fissure in the midaxillary line

    • lies the upper lobe and below it lies the middle lobe; below and posterior to the oblique fissure lies the lower lobe.

PLEURAE

  • Pleura: AKA pleural membrane– double-layered serous membrane

  • Parietal Pleura: superficial layer

    • lines the wall of the thoracic cavity

  • Visceral Pleura:  covers the lungs themselves

  • Pleural Cavity: contains a small amount of lubricating fluid secreted by the membranes.

    • Pleural Fluid: reduces friction between the membranes, allowing them to slide easily over one another during breathing

      • Surface tension: when the two membranes to adhere to one another just as a film of water causes two glass microscope slides to stick together

    • pleurisy or pleuritis: inflammation of the pleural membrane

  • Cervical pleura:  extends up into the neck, lining the undersurface of the suprapleural membrane

    • It reaches a level 1 to 1.5 in. (2.5 to 4 cm) above the medial third of the clavicle.

  • Costal pleura: lines the inner surfaces of the ribs, the costal cartilages, the intercostal spaces, the sides of the vertebral bodies, and the back of the sternum

  • Diaphragmatic pleura: covers the thoracic surface of the diaphragm

    • Costodiaphragmatic recess:  lower area of the pleural cavity into which the lung expands on inspiration

  • Mediastinal pleura:  covers and forms the lateral boundary of the mediastinum

    • Lung root

  • Costodiaphragmatic recesses:  slit like spaces between the costal and diaphragmatic parietal pleura that are separated only by a capillary layer of pleural fluid

  • Costomediastinal recesses: situated along the anterior margins of the pleura. 

    • They are slit like spaces between the costal and mediastinal parietal pleurae, which are separated by a capillary layer of pleural fluid.

  • Pleural effusion: excess fluid accumulates in the pleural space

  • Lines of Pleural Reflection: indicate the limits of the parietal pleura where it lies close to the body surface

BORDERS OF THE PLEURA

  • Anterior Border of the Right Pleura: runs down behind the sternoclavicular joint, almost reaching the midline behind the sternal angle

    • continues downward until it reaches the xiphisternal joint

  • Anterior Border of the Left Pleura: has a similar course, but at the level of the fourth costal cartilage it deviates laterally and extends to the lateral margin of the sternum to form the cardiac notch.

    •  turns sharply downward 

    • to the xiphisternal joint

  • Lower border of the pleura: both sides follows a curved line, which crosses the 8th rib in the midclavicular line and the 10th rib in the midaxillary line, and reaches the 12th rib adjacent to the vertebral column

  • Costodiaphragmatic Recess: The distance between the two borders corresponds to it

BLOOD SUPPLY TO THE LUNGS

  • 2 sets of arteries

  1. Pulmonary arteries 

  2. Bronchial arteries

  • Lobar bronchi→ segmental bronchi

    • there are 10 segmental bronchi in each lung

  • Bronchopulmonary segment: The portion of lung tissue that each segmental bronchus supplies

  • Lobules: small compartments of the bronchopulmonary segments of the lungs

    • wrapped in elastic connective tissue

    • contains:

      • a lymphatic vessel

      • an arteriole

      • a venule

      • a branch from a terminal bronchiole

  • Respiratory bronchioles: microscopic branches from the terminal bronchioles and lobule

  • Alveolar ducts: subdivision of respiratory bronchioles

BRONCHOPULMONARY SEGMENTS

  •  the anatomic, functional, and surgical units of the lungs

  • surrounded by connective tissue

  • Right lung (10)

    • Superior lobe

      • apical 

      • posterior 

      • anterior

    • Middle Lobe

      • Lateral 

      • Medial

    • Inferior Lobe

      • Superior (apical)

      • Medial Basal

      • Anterior basal

      • lateral basal

      • posterior basal

  • Left lung (11)

    • Superior lobe

      • apical 

      • posterior

      • anterior

      • superior

      • lingular

      • inferior lingular

    • Inferior lobe

      • superior (apical)

      • medial basal

      • anterior basal

      • lateral basal

      • posterior basal

THE BRONCHI

  • trachea bifurcates behind the aortic arch into

    • right and left principal (primary/ main) bronchi

LOBAR BRONCHUS

Reference: PPT

  1. R & L Main bronchus

  2. Lobar bronchi

  3. Bronchopulmonary segment

  4. Lobules

  5. Respiratory bronchioles

  6. Alveolar ducts

  • Right main bronchus

    • superior lobar bronchi

    • middle lobar bronchi

    • inferior lobar bronchi

  • Left main bronchus

    • superior bronchi

    • inferior bronchi


PRINCIPAL BRONCHi

  • formed by the division of the trachea

  • enters the lung at the hilus (medial depression)

  • Bronchi subdivide into smaller and smaller branches

  • Right bronchi

    • right is wider, and more vertical than the left

    • 1 in. (2.5 cm long)

    • Before entering the hilum of the right lung, the principal bronchus gives off the superior lobar bronchus

    • On entering the hilum, it divides into a middle and an inferior lobar bronchus.

  • Left Principal Bronchus

    • narrower, longer, more horizontal 

    • 2 in, (5cm) long

    • passes to the left below the arch of the aorta and in front of the esophagus

    • On entering the hilum of the left lung, the principal bronchus divides into a superior and an inferior lobar bronchus.

RESPIRATORY TREE DIVISIONS

  1. Primary bronchi/ Principal bronchi

  2. Secondary/Lobar Bronchi

  3. Tertiary/ Segmental Bronchi

  • accompanied by a branch of the pulmonary artery

  1. Bronchiole

    1. Respiratory bronchiole: outpouching where gaseous exchange takes place

    2. Terminal bronchiole: have no supporting cartilage

  2. Alveoli

    1. Alveolar Duct: end of the respiratory bronchioles

    2. Alveolar Sac: thin-walled outpouchings

    3. Alveolus: surrounded by capillaries

  • Respiratory membrane: where gas exchange takes place within the alveoli

 

BRONCHIOLES

  • All but the smallest branches have reinforcing cartilage

  • Terminal bronchioles end in alveoli

RESPIRATORY ZONE

  • Structures

    • Respiratory bronchiole

    • Alveolar duct

    • Alveoli

  • Site of gas exchange

ALVEOLI

  • Structure 

    • Alveolar Duct

    • Alveolar Sac

    • Alveolus

  • Alveolar Sac: terminal dilation of an alveolar duct

RESPIRATORY MEMBRANE (AIR-BLOOD BARRIER)

  • Thin squamous epithelial layer lining alveolar walls

  • Pulmonary capillaries cover external surfaces of alveoli


GAS EXCHANGE

  • Gas crosses the respiratory membrane by diffusion

    • Oxygen enters the blood

    • carbon dioxide enters the alveoli

  • Macrophages: add protection

  • Surfactant: coats gas-exposed alveolar surfaces


EVENTS OF RESPIRATION

  • Pulmonary ventilation: moving air in and out of the lungs

  • External respiration: gas exchange between the pulmonary blood and alveoli

  • Respiratory gas transport: transport of oxygen gas and carbon dioxide via the bloodstream

  • Internal respiration: gas exchange between blood and tissue cells in systemic capillaries


MECHANICS OF BREATHING

  • Pulmonary ventilation

  • depends on volume changes in the thoracic cavity

  • volume changes lead to pressure changes

    • which lead to the flow of gasses to equalize pressure

  • 2 phases

    • Inspiration: flow of air INTO the lung

    • Expiration: air LEAVING the lung

INSPIRATION

  • Diaphragm and intercostal muscles contract

  • Size of the thoracic cavity increases

  • External air is pulled into the lungs due to an increase in intrapulmonary volume

EXPIRATION

  • Largely, a passive process which depends on natural lung elasticity

  • As muscles relax, air is pushed out of the lungs

  • Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage

PRESSURE DIFFERENCES IN THE THORACIC CAVITY

  • Intrapleural pressure: Normal pressure within the pleural space is always negative

  • Differences in lung and pleural space pressures keep lungs from collapsing

NONRESPIRATORY AIR MOVEMENTS

  • Can be caused by reflexes or voluntary actions

  • Examples

    • Cough/ sneeze: clears lungs of debris

    • Laughing

    • Crying

    • Yawn

    • Hiccup

RESPIRATORY VOLUMES AND CAPACITIES

  • Tidal volume (TV): Normal breathing moves about 500 ml of air with each breath

  • Many factors that affect respiratory capacity

    • A person’s size

    • sex

    • age

    • physical condition

  • Residual volume of air: after exhalation, about 1200 ml of air remains in the lungs

  • Inspiratory reserve volume (IRV): Amount of air that can be taken in forcibly over the tidal volume

    • Usually between 2100-3200 ml

  • Expiratory reserve volume (ERV): Amount of air that can forcibly exhaled

    • Approximately 1200 ml

  • Residual volume: air remaining in the lung after expiration

    • about 1200 ml

  • Vital capacity: the total amount of exchangeable air

    • Vital Capacity= TV (tidal volume) + IRV (inspiratory reserve volume) + ERV (expiratory reserve volume)

    • Dead space volume: air that remains in conducting zone and never reaches alveoli 

    • about 150 ml

  • unctional volume: air that actually reaches the respiratory zone

    • usually about 350 ml

  • Spirometer:used to measure respiratory capacities

RESPIRATORY CAPACITIES