The RESPIRATORY System - Davis School District / … •External Portion –Supporting bony...
Transcript of The RESPIRATORY System - Davis School District / … •External Portion –Supporting bony...
Respiration
• The exchange of gases between the atmosphere, blood, and cells
• Pulmonary Ventilation - the exchange of air between the atmosphere and lungs
• External (Pulmonary) Respiration - gas exchange between the lungs and blood
• Internal (Tissue) Respiration - gas exchange between the blood and cells
Functions of the Respiratory System
• Provides structures and mechanisms for gas exchange
– Intake of O2
– Elimination of CO2
• Helps maintains body’s pH
• Sense of smell
• Speech and sound production
Nose
• External Portion
– Supporting bony framework
– Cartilage - Skin
– Mucous membranes
– Nostrils or external nares
• Internal Portion - large cavity within the skull
– Connects the external nose to the pharynx through two openings (Internal Nares)
Nose
• Nasal Cavity - large cavity that contains both the external and internal nose cavities
• divided into the right and left sides by the NASAL SEPTUM
Functions of the Nose
• Warming, moisturizing and filtering incoming air
• Smell (reception of olfactory stimulus)
• Resonating chamber for speech
Pharynx
• Funnel-shaped tube about 13 cm long
• Extends from the internal nares down to the cricoid cartilage of the larynx
• Walls composed of skeletal muscle lined with a mucous membrane
• Divided into three areas– Nasopharynx
– Oropharynx
– Laryngopharynx
Larynx (Voice Box)
• A short passageway that connects the pharynx with the trachea
• Walls of the larynx is composed of 9 pieces if cartilage– Three single pieces of cartilage
• epiglottic cartilage (Epiglottis)
• thyroid cartilage (Adam’s Apple)
• cricoid cartilage (attaches the Larynx to the Trachea)
– Three paired pieces of cartilage• arytenoid - corniculate - cuneiform
Trachea
• Tubular passageway about 12 cm long and 2.54 cm in diameter
• Anterior to the esophagus
• Extends from the larynx to about the 5th thoracic vertebrae
• Composed of 16 - 20 C-shaped cartilage rings stacked upon one another– Hyaline cartilage rings
– Covers the anterior and lateral walls
Trachea
• Non-cartilaginous posterior softer portion of the trachea allows for expansion of the esophagus during swallowing
• Lined with ciliated epithelium
• The point where the trachea bifurcates is called the carina– About the 5th thoracic vertebrae
Bronchi
• Tubes that branch off of the trachea at the carina and extend into the lungs
• Left Primary Bronchus (Left Mainstem Bronchus)
• Right Primary Bronchus (Right Mainstem Bronchus)
– Shorter and more vertical
– Swallowed objects more likely to lodge in the right primary bronchus than the left
Bronchi
• Also composed of cartilaginous rings
• Continue branching as they enter the lungs into a structure called the bronchial tree– Trachea
-Mainstem (Primary) Bronchi - Secondary (Lobar) Bronchi
- Segmental (Tertiary) Bronchi - Terminal Bronchioles
- Respiratory Bronchioles - Alveolar Ducts
Bronchioles
• Bronchioles are smaller air passages which branch from the bronchi. Bronchioles are small, muscular tubes with a narrow diameter. Changes in the size of the bronchioles help direct the flow of air to various parts of the lungs.
Alveolar Ducts
• Alveolar ducts are enlarged chambers found at the end of the bronchioles. These very fine passageways end at the alveolar sacs and connect to the alveoli.
Alveoli
• A cup shaped out pouching of epithelial tissue
• Place where external respiration occurs (gas exchange between the lungs and the blood)
• Lungs contain 300 - 500 million alveoli– Surface area of about 750 sq. ft.
– The size of a Tennis Court
Pharynx
• Funnel-shaped tube about 13 cm long
• Extends from the internal nares down to the cricoid cartilage of the larynx
• Walls composed of skeletal muscle lined with a mucous membrane
• Divided into three areas– Nasopharynx
– Oropharynx
– Laryngopharynx
Structures of the Larynx
• Epiglottis
• Glottis
• Hyoid Bone
• Thyroid Cartilage
• Cricoid Cartilage
• True and False Vocal Cords
Epiglottis
• Large leaf-shaped piece of cartilage lying on top of the larynx
– The stem of the epiglottic cartilage is attached to the thyroid cartilage
• Leaf portion of the cartilage is unattached and acts like a trap door covering the opening to the trachea which is called the glottis.
– Dependent upon breathing or swallowing
Glottis
• The opening from the pharynx to the larynx that contains the vocal cords
– Vocal Cords - mucous membrane folds that extend across the glottis in two layers
• upper layer or folds - false vocal folds
• lower layer or folds - true vocal folds
• Sounds originate from vibration of these true vocal cords
Hyoid Bone
• Is located in the neck between the lower jaw and the larynx.
• It does not articulate with any other bones.
• It serves as the posterior attachment for the tongue and helps in swallowing.
Thyroid Cartilage
• The thyroid cartilage is the largest cartilage of the larynx.
• It give the larynx its characteristic triangular shape.
• Nicknamed the Adam’s Apple because of its enlarged size due to the influence of testosterone.
Cricoid Cartilage
• The most inferior cartilage of the larynx.
• Used as a landmark to perform a tracheotomy.
True Vocal Cords
• The most inferior of the horizontal folds in the larynx.
• Contain elastic fiber which vibrate to create sound.
False Vocal Cords
• The most superior of the folds in the larynx.
• Help the glottis close during swallowing to prevent food from entering the lower respiratory passages.
Lungs
• Paired - cone shaped organs that occupy most of the thoracic cavity
• Separated from each other by the heart and other structures of the mediastinum
• Surrounded by a double layered serous membrane called the pleural membrane
Features of the Lungs
• Apex - the pointed, superior portion of the lungs.
• Base – the broad, inferior surface of the lungs which rests on the diaphragm.
Pleural Membrane
• Parietal Pleura - outer layer of the pleural membrane
– Attached to the thoracic wall
• Visceral Pleura - inner layer of the pleural membrane
– Attached to the lungs themselves
• Between the parietal pleura and the visceral pleura is a potential space called the pleural cavity
– Contains pleural (serous) fluid (reduces friction)
Gross Anatomy of the Lungs
• Extend from the diaphragm to an area about 2.54 cm above the clavicles on both sides of the thoracic cavity
• Base
• Apex
• Hilus
• Lobes
Lobes and Fissures
• Each lung is divided into lobes by one or more fissures
• There are three lobes in the right lung and two lobes in the left lung.
Pleural Cavity
• The mediastinum divides the thoracic cavity into two pleural cavities, each of which contains one lung.
Gas Exchange
• Gas exchange occurs in the alveoli due to the difference in the partial pressures of oxygen and carbon dioxide in the capillary blood and the alveoli.
• Since the concentration of oxygen is greater in the alveoli, it diffuses into the capillary blood.
• Since the level of carbon dioxide is higher in the capillary blood than in the alveoli, carbon dioxide diffuses out of the blood and into the alveoli.
Lung Parameters
• Tidal Volume (TV) - 500 ml - volume of air moved in and out of the lungs during breathing
• Vital Capacity (VC) - 4500 ml -maximum volume of air that can be exhaled after taking the deepest possible inhalation
VC - TV + IRV + ERV
Physiology of Ventilation
• Ventilation - the process of inhaling and exhaling air in and out of the lungs
• Pulmonary Ventilation - the process by which air flows between the lungs and the external environment
• Due to a change in pressure between the atmosphere and the air in the lungs
Inspiration (Inhalation)
• Bringing air into the lungs from the external environment
• The lungs themselves contain no muscles and thus depend upon the relationship with the muscles of the walls of the thoracic cavity to alter lung volumes
Expiration (Exhalation)
• Movement of air from the lungs to the external environment
• Normally a passive process (no energy or muscular contractions required)
• Dependent upon muscle and lung elasticity
• May become active during high levels of physical activity– Most people require ventilation rates above
55% - 65% of their vital capacity for expiration to become active
Chemical Stimuli
• Determines how fast and how deeply an individual breathes
• Very sensitive to the levels of CO2 and H+ ion concentration in the blood
• Monitored by chemoreceptors at:
– carotid arteries, aorta, and the medulla oblongata.
Bronchiogenic Carcinoma(Lung Cancer)
• Most fatal cancer in the U.S.
• Highly metastatic
• Usually linked with cigarette smoking
• Starts in the walls of the bronchi due to irritation of the bronchiole epithelium
• Common irritants include smoking, pollution, dust particles
• 20 times more prevalent in smokers than non- smokers
Emphysema
• “Blown up or full of air”
• A condition where the alveolar walls lose their elasticity and remain filled with air during expiration
• Alveoli become damaged and eventually merge together to form large air sacs with reduced overall volume
• Patients often develop a barrel chest
• Generally caused by cigarettes, pollution, industrial dust particles
Influenza
•Caused by one of many viruses
• Antibiotics cannot help
• Medications used to treat the symptoms– sneezing - coughing
– congestion - rhinorrhea
• May result in rhinitis: inflammation of the nasal mucosa
• Commonly known as the flu
Pneumonia
• Acute infection or inflammation of the alveoli of the lungs
• Most common infectious cause of death in the U.S.
• Alveolar sacs fill with fluid and dead white blood cells reducing the amount of functional surface area of the lungs
• Most commonly caused by bacterium
– Streptococcus pneumoniae
• Affects those in poor health or compromised immune system
Sudden Infant Death Syndrome (SIDS)
• 10,000 infant deaths per year in the U.S.
• Cause is not known but thought to be caused by an infectious agent or compressed carotid artery
• Most deaths occur in the fall or winter
• Over 50% of SIDS death children had an upper respiratory infection within the past two weeks
• May also be caused by improper positioning for sleeping in the crib
Tuberculosis (Tb)
• Caused by a bacterium– Mycobacterium tuberculosis
• An infectious communicable disease that destroys the lung tissue and pleura
• Replaced by fibrous connective tissue called tubercles
• Disease is spread by inhalation of the bacterium