The Respiratory System

Ventilation

room air

80% nitrogen, 20% oxygen, and other gases

moves into the lungs for external respiration

Accessory Muscles of Respiration

• external intercostal muscles

• sternocleidomastoid

• scalenes

• external oblique

• rictus abdomens

• internal intercostal muscles

Functions of Accessory Muscles

• used in stressed situations

• when you need to increase air moving in and out to maintain oxygen levels

External Intercostal Muscles

• between the ribs

• when they contract it pulls up the ribs

Sternocleidomastoid

pull up against the head and help raise the first ribs, sternum, and clavicle

Scalenes

attach to the first rib and clavicle, pull them up

Internal Intercostal Muscles

pull the chest down so forced expiration can occur

Alveoli

• where gas exchange takes place

• has nucleus

Pulmonary Suffocation

the enclosure of the mouth or the nose at the throat by foreign body

Alveolar Suffocation

obstruction causing the exchange of oxygen will be blocked

Tissue Suffocation

obstruction of flow from the capillary bed

Cellular Suffocation

a failure of oxygen to reach the cells due to various factors such as toxic substances or metabolic issues.

Medullary Rhythmically Centre

establishes a normal rhythm in the brain

Pneumothorax

• air in the chest

• create loss of vacuum

Respiratory System vs Cardiovascular System

Respiratory: provides exchange of gases, adjusts pH of body fluids

Cardio: transports blood containing the gases between the lungs and body cells

both: supply O2 and eliminate CO2

Steps in Respiration

1. pulmonary ventilation

2. external respiration

3. internal respiration

Pulmonary Ventilation

• the inhalation and exhalation of air between the atmosphere and the pulmonary alveoli of the lungs

• inhalation permits O2 to enter the lungs

• exhalation permits CO2 to leave the lungs

External Respiration

• the exchange of gases between the pulmonary alveoli of the lungs and the blood in pulmonary capillaries across the respiratory membrane

• pulmonary capillary blood gains O2 and loses CO2

Internal Respiration

• the exchange of gases between blood in systemic capillaries and tissue cells

• the blood loses O2 and gains CO2

• within cells the metabolic reactions that consume O2 and gives off CO2 during the production of ATP (cellular respiration)

Upper Respiratory System

nose, nasal cavity, pharynx, and associated structures

Lower Respiratory System

larynx, trachea, bronchi, and lungs

Conducting Zone

• consists of a series of interconnecting cavities and tubes both outside and within the lungs

• include nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchial

Conducting Zone Functions

• filters, warm, and moisten air

• conduct it into the lungs

Respiratory Zone

• consists of tubes and tissues within the lungs where gas exchange occurs

• includes respiratory bronchioles, alveolar ducts, alveolar saccules

• main site of gas exchange between air and blood

External Nose

• visible on the face

• consists of supporting framework of bone and hyaline cartilage

• somewhat flexible

Bony Framework

frontal bone, nasal bones, maxillae

Cartilaginous Framework

• several pieces of hyaline cartilage connected to each other and certain skull bones by fibrous connective tissue

• nasal septal cartilage

• lateral nasal cartilage

• alar cartilages

External Nose Functions

• warming, moistening, and filtering incoming air

• detecting olfactory stimuli

• modifying speech vibrations as they pass through the resonating chambers

Internal Nose

• nasal cavity

• lies inferior to the nasal bone and superior to the oval cavity

• lined with muscle and mucus membrane

• nasal septum

Nasal Septum

• divides the nasal cavity into left and right sides

• anterior portion: hyaline cartilage

• remainder is formed by the vomer and perpendicular plate of the ethmoid, maxillae, and palatine bones

Pharynx Overview

• 13 cm long

• starts at the choanae and extends to the level of the cricoid cartilage

• wall composed of skeletal muscles and is lined with mucus membrane

Pharynx Functions

• deglutition(swallowing)

• passageway for air and food

• provides a resonating chamber for speech/sounds

• participates in immunological reactions against foreign invaders

Nasopharynx

• superior portion of pharynx

• soft plate

• contains pharyngeal tonsil

• receives air from nasal cavity and packages of dust-laden mucus

Solf Plate

• forms posterior portion of the roof and mouth

• 5 openings include two choanae, two that lead into the auditory tubes and the opening into the oropharynx

Oropharynx

• has respiratory and digestive functions

• common passageway for air, food, and drink

• lined with nonkeratinized stratified squamous epithelium

• palatine and lingual tonsils

Laryngopharynx

• begins at level of hyoid bone

• inferior end opens into the esophagis posteriorly and the larynx anteriorly

• both respiratory and digestive pathway lined with nonkeratinized stratified squamous epithelium

Larynx Overview

• nine pieces of cartilage

• singly cartilages

• paired cartilages

Singly Cartilages Include

• thyroid cartilage

• epiglottic cartilage

• cricoid cartilage

Paired Cartilages Include

• aryenoid

• cuneiform

• curniculate

Thyroid Cartilage

• largest in larynx

• consists of two fused plates that form the anterior wall of the larynx

Epiglottic Cartilage

• elastic cartilage

• mucus membrane covering

Cricoid Cartilage

• horn shaped elastic cartilage

• located at the apex of each arytenoid cartilage

Cuneiform Cartilage

• elastic cartilages anterior to the corniculate cartilages

• support the vocal folds and lateral aspects of the epiglottis

Structures of Voice Production

• vocal folds

• bands of elastic ligaments are stretched between the rigid cartilages of the larynx

• intrinsic laryngeal muscles attach to both rigid cartilage and vocal folds

• contracting and relaxing the muscles varies the tension in the vocal folds

Vocal Folds

the principle structures of voice production

When Muscles of Voice Production Contract

• they move the cartilages, pulling the elastic ligaments tight

• this stretches the vocal folds out into the airway so the rima glottidis is narrowed

Pitch Controlled by

• controlled by the tension on the vocal folds

Pitch - when pulled taut

they vibrate more rapidly at a higher pitch

Pitch - Decreasing Tension

• causes vibrating more slowly and produce lower pitch sounds

• due to the influence of androgens vocal folds are thicker and longer in males and vibrate more slowly

Sound Originates From

the vibration of the vocal folds

Whispering

• accomplished by closing all but the posterior portion of the rima glottidis

• vocal folds do not vibrate

• as size of oral cavity changes, its resonance qualities change which imparts a vowel-like pitch to the air as it rushes towards the lips

Laryngitis

• inflammation of the larynx most often caused by respiratory infection or irrants such as smoking

• causes hoarseness or loss of voice by interfering with the contraction of the folds or by causing them to swell to the point of not being able to vibrate freely

Cancer of the Larynx

• found most commonly in those who smoke

• characterized by hoarseness, pain during swallowing, or pain radiating to an ear

• treatment consists of radiation therapy and/or surgery

Tracheal Wall Layers (Deep to Superficial)

• respiratory mucosa

• submucosa

• hyaline cartilage

• adventitial layer

Respiratory Mucosa

• deepest layer

• consists of an epithelial layer of ciliates pseudostratisfied columnar epithelium and an underlying layer of latina propria that contains elastic and reticular fibers

• provides same protection against dust as the membrane lining the nasal cavity

Submucosa

• consists of areolar connective tissue that contains seromucous glands and their ducts

Hyaline Cartilage

• horizontal rings resembling the letter C

• connected by dense connective tissue

• spanned by the membranous wall of the trachea

• within membranous wall are trachealis muscle

Trachealis Muscle

elastic connective tissue that allow the diameter of the trachea to change during inhalation and exhalation

Adventitial Layer

consists of areolar connective tissue that joins the trachea and surrounding tissues

Tracheostomy

• done under general anesthesia

• a skin incision is followed by a short longitudinal incision into the trachea below the cricoid cartilage

• then an endotracheal tube is placed through the opening to provide an airway

• used for medical conditions that require a ventilator, vocal cord paralysis, throat cancer, airway burns

Intubation

• advanced through the mouth into the trachea

• a laryngoscope is used

• once vocal folds. are located the tube is placed in the inferior portion of the trachea

• used to permit air to freely pass into and out of the lungs, introduce anesthesia, medications, and O2 or to suction respiratory secretions

Lungs

• located in thoracic cavity and separated by the heart and other structures of the mediastinum

• pleural membrane

• parietal pleura

• visceral pleura

• pleural cavity

Pleural Membrane

protects the lungs in a double-layered serous membrane

Parietal Pleura

superficial layer that lines the wall of the thoracic cavity

Visceral Pleura

deep layer, covers the lungs

Pleural Cavity

• between visceral and parietal pleurae

• contains a small amount of lubricating fluid secreted by the membranes

• fluid reduces friction between the membranes allowing them to slide easily over one another

General Position of the Lungs

extend from the diaphragm to just slightly superior to the clavicles and lie against the ribs

Base of Lungs

is concave and fits over the convex area of the diaphragm

Apex of Lungs

narrow superior portion

Costal Surface of Lungs

surface of the lung lying against the ribs, matches the rounded curvature of the ribs

Mediastinal Surface of Lungs

• each lungs contains the hilum which bronchi, pulmonary blood vessels, lymphatic structures, and nerves enter and exit

• these structures held together by the pleura and connective tissue and constitute the root of the lung

Both lungs have an _______ _______ that runs downward (inferiorly) and forward (anteriorly)

oblique fissure

Left lung has ___ oblique fissure that separates superior and inferior lobe

1

Right lung has __ oblique fissure and __ horizontal fissure

1, 1

Left Lung smaller due to

• heart occupying space

Lobules

• small compartments within each bronchopulmonary segment

• wrapped in elastic connective tissue

Each Lobule Contains

• terminal bronchiole

• lymphatic vessel

• pulmonary arteriole

• pulmonary venule

Terminal Bronchioles branch into _____

respiratory bronchioles

Respiratory Bronchioles

• the beginning of the respiratory zone and divide into 2-11 alveolar ducts

Alveolar Components

• alveolar saccules

• pulmonary alveoli

Alveolar Saccules

clusters of pulmonary alveoli, each contain 20-30 alveoli

Pulmonary Alveoli

main sites of gas exchange

Pulmonary Arterioles and Venules branch into ___

a dense capillary network surrounding the alveoli

Capillaries lie directly ____ the alveolar walls

against

Types of Cells in the Alveoli

• pneumocyte Type I

• pneumocyte type II

• alveolar microphages

• fibroblasts

Pneumocyte Type I

• 95% of alveolar cells

• simple squamous epithelial cells

• form most of alveolar wall

• primary site of gas exchange

Pneumocyte Type II

• less numerous

• rounded or cuboidal

• contain microvilli

• secrete pulmonary alveolar fluid

• produce surfactant

Alveolar Microphages

• phagocytes cells

• remove dust, debris, and foreign particles

Fibroblasts

• produce elastic fibers, reticular fibres

• support alveolar walls and allow lungs to expand and recoil

Structure of Respiratory Membrane

• alveolar wall: type I and type II along with alveolar macrophages

• alveolar epithelial basement membrane

• capillary basement membrane

• capillary endothelium

Alveolar-Capillary membrane Functions

• site of diffusion of respiratory gases

• O2 diffuses from alveoli into blood

• CO2 diffuses from blood into alveoli

• thin membrane allows rapid gas exchnage

Blood Supply to the Lungs Overview

• lungs receive blood via the pulmonary and bronchial arteries

• deoxygenated blood passes through the pulmonary trunk which divides into a left and right pulmonary artery

• return of the oxygenated blood to the heart occurs by four pulmonary veins that drain into the left atrium

• pulmonary blood vessels constrict in response to localized hypoxia

• ventialtion-perfusion coupling

Left Pulmonary Artery enters…

left lung

Right Pulmonary Artery enters….

right lung

Ventilation-Perfusion Coupling

• vasoconstriction in response to hypoxia diverts pulmonary blood from poorly ventilated areas of the lungs to well-ventilated regions for more efficient gas exchange

Pulmonary Ventilation Definition

flow of air into and out of the lungs

Pulmonary Ventilation Overview

• air flows between the atmosphere and pulmonary alveoli of the lungs

• air moves into the pulmonary alveoli of the lungs when the air pressure inside the lungs is less then the air pressure in the atmosphere

• air moves out of the pulmonary alveoli of the lungs when the air pressure inside the lungs is greater than the pressure in the atmonsphere

Boyle’s Law

• if the size of a closed container is increased: the pressure of the gas inside the container decreases and if the size of the container is decreased then the pressure inside increases

• differences in pressure caused by: changes in the lung volume force air into our lungs when we inhale and out when we exhale

• if inhalation occurs: lungs must expand which increases lung volume and thus decreases the pressure in the lungs to below atmospheric pressure

To Expand Lungs:

• contraction of the diaphragm with resistance from external intercostals

Intrapleural Pressure

• pressure within the pleural cavity

• negative pressure

• as diaphragm and external intercostals contract and the overall size of the thoracic cavity increases, the volume of the pleural cavity also increases which causes intrapleural pressure to decrease