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Respiratory System - Britane Olvera Per.2 - Coggle Diagram
Respiratory System - Britane Olvera Per.2
Major functions of the respiratory system
supply body with O2 for cellular respiration
dispose of CO2, a waste product of cellular respiration
Respiratory system
External respiration: exchange of O2and CO2between lungs and blood
Pulmonary ventilation (breathing): movement of air into and out of lungs
Circulatory system
Transport of O2and CO2in blood
Internal respiration: exchange of O2and CO2between systemic blood vessels and tissues.
Upper respiratory structures and functions
Major Organs
Paranasal sinuses
Pharynx
Three regions:
Nasopharynx
Air passageway (only air) posterior to nasal cavity
Soft palate and uvula close nasopharynx during swallowing
Pharyngeal tonsils (adenoids) located on posterior wall
Oropharynx
Passageway for food and air from level of soft palate to epiglottis
Palatine tonsils located in lateral walls of fauces
Lingual tonsil located on posterior surface of tongue
Laryngopharynx
Passageway for food and air
Posterior to upright epiglottis
Extends to larynx, where it is continuous with esophagus
Connects nasal cavity and mouth to larynx and esophagus
Composed of skeletal muscle
Nose and nasal cavity
Provides an airway for respiration
Moistens and warms entering air
Filters and cleans inspired air
Serves as resonating chamber for speech
Houses olfactory receptors
Divided into two regions:
nasal cavity
Found within and posterior to external nose
Divided by midline nasal septum
Nasal vestibule: nasal cavity superior to nostrils
Nasal conchae
Functions: Filter, heat, and moisten air
Paranasal sinuses
Functions: Lighten skull, secrete mucus, and helps warm and moisten air
external nose
root (area between eyebrows); bridge, dorsum nasi (anterior
margin), and apex (tip of nose)
Nostrils (nares): bounded laterally by alae
Lower respiratory structures and functions
Consists of:
trachea
extends from larynx into mediastinum, where it divides into two main bronchi
4 inches long, 3/4 inch in diameter, and very flexible
Wall composed of three layers
Mucosa: ciliated pseudostratified epithelium with goblet cells
Submucosa: connective tissue with seromucous glands
Adventitia: outermost layer made of connective tissue
Carina
Last tracheal cartilage that is expanded and found at point where trachea branches into two main bronchi
Larynx
Functions:
Provides patent airway
Routes air and food into proper channels
Voice production
Houses vocal folds
consists of nine hyaline cartilages (except for epiglottis)
Thyroid cartilage
Cricoid cartilage
Paired arytenoid cartilages (anchor vocal cords)
Paired cuneiform cartilages
Paired corniculate cartilages
Epiglottis
Consists of elastic cartilage (not hyaline)
Vocal folds
Vocal ligaments: form core of vocal folds (true vocal cords)
Glottis: opening between vocal folds
Folds vibrate to produce sound as air rushes up from lungs
Vestibular folds (false vocal cords)
No part in sound production
Help to close glottis during swallowing
bronchi
Air passages undergo 23 orders of branching
Branching referred to as bronchial tree
From tips of bronchial tree:
Conducting zone structures give rise to respiratory zone structures
Conducting zone structures
Trachea divides to form right and left main (primary) bronchi
Right main bronchus wider, shorter, more vertical than left
Each main bronchus enters hilum of one lung
Each main bronchus then branches into lobar (secondary) bronchi
Three on right and two on left
Each lobar bronchus supplies one lobe
Each lobar bronchus branches into segmental (tertiary) bronchi
Segmental bronchi divide repeatedly
Branches become smaller and smaller
Bronchioles: less than 1 mm in diameter
Terminal bronchioles: smallest of all branches
Less than 0.5 mm in diameter
Respiratory zone structures
begins where terminal bronchioles feed into respiratory
bronchioles, which lead into alveolar ducts and finally into alveolar sacs (saccules)
Alveolar sacs contain clusters of alveoli
~300 million alveoli make up most of lung volume
Sites of actual gas exchange
Respiratory membrane
Blood air barrier that consists of alveolar and capillary walls
Very thin (~0.5 m); allows gas exchange across membrane by simple diffusion
Alveolar walls consist of:
Single layer of squamous epithelium
Scattered cuboidal alveolar cells secrete surfactant and antimicrobial
proteins
lungs
Lungs occupy all of the thoracic cavity except for mediastinum
Root: site of vascular and bronchial attachment to mediastinum
Costal surface: anterior, lateral, and posterior surfaces
Apex: superior tip, deep to clavicle
Base: inferior surface that rests on diaphragm
Hilum: found on mediastinal surface, it is the site for entry/exit of blood vessels, bronchi,
lymphatic vessels, and nerves
Left lung: separated into superior and inferior lobes by oblique fissure
Smaller than right because of position of heart
Cardiac notch: concavity for heart to fit into
Right lung: separated into superior, middle, and inferior lobes
Superior and middle lobes separated by horizontal fissure
Middle and inferior lobes separated by oblique fissure
Broken into two zones:
Respiratory zone: site of gas exchange
Consists of microscopic structures such as respiratory bronchioles, alveolar ducts, and alveoli
Conducting zone: conduits that tranport gas to and from gas exchange sites
Includes all other respiratory structures
Cleanses, warms, and humidifies air
Layers of the pleurae
two thin layers of tissue that protect and cushion the lungs
The inner layer (visceral pleura) wraps around the lungs.
The outer layer (parietal pleura) lines the inside of the chest wall.
Layers seperated by pleural fluid
Compare and contrast the mechanism of inspiration and expiration
Inspiration: gases flow into lungs
Active process involving inspiratory muscles
Action of the diaphragm: when dome-shaped diaphragm contracts, it moves
inferiorly and flattens out
Action of intercostal muscles: when external intercostals contract,
During same period, Pip lowers to less than Patm
Forced (deep) inspirations can occur during vigorous exercise or in people with
COPD
Accessory muscles are also activated
Expiration: gases exit lungs
Quiet expiration normally is passive process
Forced expiration is an active process that uses oblique and transverse
abdominal muscles, as well as internal intercostal muscles
Nonrespiratory air movements.
Many processes can move air into or out of lungs besides breathing
– May modify normal respiratory rhythm
– Most result from reflex action, although some are voluntary
– Examples: coughing, sneezing, crying, laughing, hiccups, and yawns
Volume and Pressure relationships in thoracic cavity
Atmospheric pressure (Patm)
Pressure exerted by air surrounding the body
760 mm Hg at sea level = 1 atmosphere
Intrapulmonary pressure (Ppul)
Pressure in alveoli
Also called intra-alveolar pressure
Fluctuates with breathing
Always eventually equalizes with Patm
Transpulmonary pressure
Transpulmonary pressure = (Ppul −Pip)
Pressure that keeps lung spaces open
Keeps lungs from collapsing
Intrapleural pressure (Pip)
Pressure in pleural cavity
Fluctuates with breathing
Always a negative pressure (<Patm and <Ppul)
Two inward forces promote lung collapse
Lungs’ natural tendency to recoil
Because of elasticity, lungs always try to assume smallest size
Surface tension of alveolar fluid
Surface tension pulls on alveoli to try to reduce alveolar size
One outward force tends to enlarge lungs
One outward force tends to enlarge lungs
Elasticity of chest wall pulls thorax outward
Negative Pip is affected by these opposing forces but is maintained by strong adhesive force between parietal and visceral pleurae
Respiratory volumes and capacities
Several respiratory volumes can be used to assess respiratory status
Respiratory volumes can be combined to calculate respiratory capacities, which can
give information on a person’s respiratory status
Spirometer: original, cumbersome clinical tool used to measure patient’s respiratory volumes
Electronic measuring devices used today
Respiratory Volumes
Tidal volume (TV): amount of air moved into and out of lung with each breath.
Averages ~500ml
Inspiratory reserve volume (IRV): amount of air that can be inspired forcibly beyond
the tidal volume (2100–3200 ml)
Expiratory reserve volume (ERV): amount of air that can be forcibly expelled from
lungs (1000–1200 ml)
Residual volume (RV): amount of air that always remains in lungs
Needed to keep alveoli open
Respiratory Capacities
Combinations of two or more respiratory volumes
Inspiratory capacity (IC): sum of TV + IRV
Functional residual capacity (FRC): sum of RV + ERV
Vital capacity (VC): sum of TV + IRV + ERV
Total lung capacity (TLC): sum of all lung volumes (TV + IRV+ ERV + RV)
Internal vs. external respiration
External respiration: diffusion of gases between blood and lungs
involves the exchange of O2 and CO2 across respiratory membranes
Partial pressure gradients and gas solubilities
Steep partial pressure gradient for O2 exists between blood and lungs
Venous blood PO2 = 40 mm Hg
Alveolar PO2 = 104 mm Hg
Drives oxygen flow into blood
Internal respiration: diffusion of gases between blood and tissues
Internal respiration involves capillary gas exchange in body tissues
Both processes are subject to:
Basic properties of gases
Composition of alveolar gas
Disorders of the respiratory system
Atelectasis: lung collapse due to
Plugged bronchioles, which cause collapse of alveoli, or
Pneumothorax, air in pleural cavity
Can occur from either wound in parietal pleura or rupture of visceral pleura
Treated by removing air with chest tubes
When pleurae heal, lung reinflates
Laryngitis: inflammation of the vocal folds that causes the vocal folds to swell, interfering with vibrations
Smoking inhibits and ultimately destroys cilia
Heimlich maneuver: procedure in which air in victim’s lungs is used to “pop out,” or expel, an obstructing piece of food
Pleurisy: inflammation of pleurae that often results from pneumonia