Respiratory system Flashcards
Main functions
Respiratory system-
The main function of the respiratory system is to eliminate carbon dioxide and take in oxygen. Other functions include: regulation of blood pH, receptors for smell, elimination of water in exhaled air, filtration of air, and resonance chambers for sound.
Respiration (breathing) includes 4 separate steps-
- Pulmonary ventilation- breathing Inhalation and exhalation.
- External (pulmonary) respiration- exchanges of gases between the alveoli of the lungs and blood capillaries.
- Transport of respiratory gases- gases are carried in the blood via cardiovascular system.
- Internal (tissue) respiration - exchange of gases between tissue and systemic capillaries.
Upper respiratory system-
Nose,pharynx (throat), paranasal sinuses and associated structures.
Lower respiratory system-
Larynx,trachea,main(primary) bronchi, bronchioles,lungs and associated structures.
Conducting zone-
structures are responsible for filtering, moistening, warming, and moving the air. Structures from the nose to the terminal bronchioles form a tube for air transportation to the lungs.
Respiratory zone-
Structures are involved in gas exchange are respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli ( all microscopic structures)
Nose-
External structures are formed by the frontal bone, maxillary bones and nasal bones. Bulk of the nose is made of hyaline cartilage! The nostrils (nares) are formed of hyaline cartilage and Dense regular (fibrous) connective tissue.
Nose Functions-
Warms, moistens and filters air inhaled through the nares. Provides for our sense of smell. olfactory epithelium contains olfactory receptors. Modification of speech sounds by having chambers that resonate (echo)
Internal structures of the nose-
Nasal vestibule- the anterior, portion of the nasal cavity just inside the nose. It conatins coarse hairs that filter air that enters the nose (external defense).
Nasal Conchae- located just past the vestibule, 3 shelves located on either side of the nasal septum (superior, middle and inferior). Nasal Meatuses- the passage way just underneath each conchae.
Nasal septum- divides nasal cavity in 2 chambers; septal (hyaline cartilage), the vomer, and perpendicular plate of the ethmoid bone.
Floor of the nasal cavity- formed by the palatine bones and palatine processes of the maxillae( hard plate ) and soft palate ( a muscular extension of the hard plate)
Roof of the nasal cavity is formed by the ethmoid bones.
Paranasal sinuses( frontal, maxillae, sphenoid and ethmoid bones) surround the nasal cavity and have ducts that open into the nasal cavity. Posterior nasal aperture- located in the posterior portion of the nasal cavity and allows air to exit the nasal caity into the Nasopharynx.
Tissue of the Nasal cavity-
Pseudostratified ciliated columnar epithelium (PSCCE) with goblet cells for mucus production.
Pharynx (throat) -
a passage way for food and air! ( Its divided into 3 sections)
Nasopharynx - the superior most section that extends from the posterior nasal aperture to the soft palate, made of pesudostratified ciliated columnar epithelium (PSCCE).
Oropharynx- middle section of the pharynx that extends from behind the soft palate to the level of hyoid.
Laryngopharynx- inferior section of the pharynx that extends from hyoid bone to the larynx. (non-keratinized stratified squamous epithelium) NKSSE.
Opening that are located in the Nasopharynx-
Pharyngotympanic (auditiry) tube and the Pharyngeal tonsil.
The Fauces-
is the opening from the oral cavity located in the Oropharynx. is made of (non-keratinized stratified squamous epithelium. (NKSSE) the palatine and lingual tonsil are in the Oropharynx too!
Larynx (voice box)- lots of cartilages!!
Extends from laryngopharynx to the trachea.
Cartilage of the Larynx-
thyroid cartilage (Adam's apple)- thick hyaline cartilage that attaches to hyoid bone via thyrohyoid membrane. Epiglottis ("guardian of the airway")- elastic cartilage that is atached to the thyroid cartilage inside the V. Durring swallowing, the epiglottis flaps over to prevent food from entering the glottis.
Cricoid cartilage- a single complete ring of hylaine cartilage that attaches to the trachea via cricotracheal ligament and attaches to the thyroid cartilage via the cricothyroid ligament. Arytenoid cartilage (2) - hyaline cartilage that attaches to the true vocal cords (vocal folds) and the muscles that tighten the vocal cords. Corniculated cartilage (2) - horn shaped hyaline cartilage located on the top of each arytenoid cartilage. Cuneiform cartilage (2) - wedge - shaped hyaline cartilage located anterior and superior to the other two pair.Tissue types- Voice production-
above the vocal folds are mad out of NKSSE, and below the vocal folds is PSCCE. Vestibular folds (false vocal cords)- located superior to the vocal folds( true vocal cords). Glottis - the area that includes the vocal folds and the opening between the vocal folds.
Speech- voice production,
Speech is produced by altering the size of the glottis and the expired air that passes through it. The lenght of the true vocal folds is adjusted by the contraction and relaxation of the intrinsic laryngeal muscles. In general, the tighter the folds are pulled the faster the vibration and therefore the higher the pitch. Men have deeper voices because of the thicker thyroid cartilage and thicker vocal cords, which can not be pulled as tight and therefore a lower pitch.
Other structures that act as resonating chambers:
Paranasal sinuses, pharynx,nasal,and oral cavities.
Trachea (windpipe) 4 layers,
12cm in lenght by 2.5 cm in diameter, extends from the larynx to T2 where it divides into right and left main bronchi. 1. Mucosa- lined with PSCCE (pseudostratified ciliated columnar epitheliun), goblet cells that produce mucus and capillaries that warm the air. Located closest to the lumen. 2. Submucosa-below the mucosa, composed of areolar connective tissue, and seromucous glands. 3. Hyaline cartilage and muscle- C-shaped rings of hyaline cartilage that opens at the back, smooth muscle(trachealis muscle) attaches to the trachea. 4. Adventita- areolar connective tissue provides an outer covering for the traches and attaches it to the surrounding tissues.
Bronchi- the conducting zone
At the superior border of T5 the conducting system branches into two primary (main) bronchi, the right and left. The right primary (main) bronchus is wider, shorter and more vertical than the left primary (main) bronchus. The conducting Zone, Carina - within the trachea there is mucosa that is especially sensitive to foregin objects and this triggers the coughing reflex. lobar bronchi - aka secondaty bronchi. There is one lobar bronchus for each lobe of the lung, 3 on the right and 2 on the left. segmental (tertiary) bronchi- smaller branches from the lobar bronchi. Bronchioles - smaller branches from the tertiary bronchi that have an internal diameter less than 1mm. Terminal bronchioles - the last branch before the repiratory bronchioles. The respiratory bronchioles directly enter the alveolar ducts.
Tissue in Bronchi-
Tissue in the bronchi is similar to the trachea but as the conducting tubes get smaller and smaller, the following changes occur: The cartilage becomes more and more irregular with no cartilage found in the bronchioles. The epithelium chanhes from PSCCE to simple columnar and then simple cuboidal. The amount of smooth muscle increases.
The respiratory Zone - Respiratory bronchioles within the lungs feed into alveolar ducts which feed into alveolar sacs (bunches if alveoli)
Alveoli have diffrent cells present: Type I alveolar cells - from the part of the membrane for gas exchange, composed of simple squamous cells. Type II alveolar cells (septal cells) - made up of cuboidal epithelium with microvilli, these cells secrete surfactant wich reduces the surface tension of water and keeps the alveoli from collapsing. Aveolar macrophages (dust cells) -wandering macrophages that pick up dust and debris.
Respiratory membrane ( were the exchange of gases occur). It consists of. 1-3
- Alveolar epithelium (Type I cells) 2. two fused basement membranes (one from the alveolus and one from the capillary) 3. the capillary endothelium.
Lungs-
Each lung has its own serous membrane known as the pleural membrane. (parietal pleura and visceral pleura with the pleura cavity containing pleural fluid in between). Apex- superior point of each lung, Base- broad inferior portion that rests on the diaphragm. Costal surface- curves of the lungs that match the curvature of the ribs. Mediastinal surface- located medially for each lung and includes a hilus for each lung. Hilum- (aka hilus) blood vessels, lympatic vesseles and nerves enter and exit at this depression. Cardiac notch - impression on the left lung that makes room for the heart.
Lung Anatomy-
The left lung is divided into 2 lobes (superior and inferior) by the oblique fissure. The right lung is divided into 3 lobes( superior, middle and inferior) by the horizontal and oblique fissures. Each lobe is further divided inti bronchopulmonary segments and the segments are further divided into lobules. Eavh segment has its own lymphatic vessel, arteriole, venule and terminal bronchiole. The segments are seperated from one another by connective tissue and so they can be surgically removed if necessary.
Mechanics of Breathing-
Atmospheric pressure- the pressure due to the gases surrounding the body at a given elevation, 760mm Hg at sea level.
Negative pressure - a pressure that is lower than atmospheric pressure.
Positive pressure - a pressure that is greater than atmospheric pressure.
Intrapulmonary pressure- P pul the pressure within the alveoil of the lungs, changes with breathing.
Intrapleural pressure - P ip, the pressure within the pleural cavity,changes with breathing but is always about 4mm Hg less than P pul.
Transpulmonary pressure - the diffrence between the intrapulmonary and the intrapleural pressure, ultimatley keeps the lungs from collapsing because it is at a possitive pressure, at least (+4mmHg).
Forces that favor the collapse of the lung -
if the surface tension of the fluid in the alveoli has the natural tendency to recoil because its elastic tissue.
Forces that keep the lungs inflated -
The elasticity of the thoracic cage, the tendency of the rib cage and supporting muscles to pull the thoracic cage outward and the transpulmonary pressure.
Pulmonary ventilation - Inspiration and Expiration
This involves the exchange of gases between the atmosphere and the lungs ( specifically the aliveoli). Movement of air is from high to low pressure.
Boyle’s law -
Pressure and volume are inversely proportional to each other.
Inspiration (Inhalation) -
If the thoraic cavity changes size, the pressure changes in the opposite direction. (eupena = normal breathing) :
The diaphragm contracts,moving down and flattening out. This results in a increase in the vertical (superior to inferior) dimension of the thoracic cavity. The external intercostal muscles also cotract which increases the lateral and anterior to posterior dimensions of the thoracic cavity. Boyle’s law again, pressure and volume are inversely proportional. Ex: AMP = 760mmHg and intrapulmonary pressure = 758mmHg decrease 1-3 mm HG just prior to inspiration. Similarly, intrapleural pressire also decreases slightly but is always about 4mm Hg less than the intrapulmonary pressure. If the intrapleural pressure and intrapulmonary pressure were equal the lungs would collapse.
Pneumothorax-
air entering the intrapleural cavity causing the lungs to collaps, the air must be removed and the hole sealed to return the negative pressure.
Forced inspiration -
contraction of the sternocleiomastoid muscle and the scalenes elevate the rib cage even more.
Expiration (Exhalation) - For quiet expiration,
- diaphragm and intercostal muscles relax which decreases the volume of the thoracic cavity.
- the elastic lungs and chest recoil from being stretched, decreasing the the intrapulmonary volume.
- Intrapulmonary pressure rises, creating the pressure difference necessary for air to flow out of the lungs.
Forced expiration:
abdominals and intercostal muscles contract.
Physical factors that affect pulmonary ventilation-
Surface tension - at an interface between any liquid and a gas, there is surface tension because the water molecules are more attracted to each other than gas molecules. High surface tension corresponds to stiffness or inability to stretch. If the film on the alveoil was only water they would collapse upon themselves in between breaths.
Compliance - this term refers to the “ streatchability of the lungs. High compliance is determined by elasticity and surface tension. Low surface tension means compliant.
Decreased compliance- can be due to scar tissue ( loss of elasticity) edema or a decreases in the amount of surfactant.
Increase in compliance - can occur from destruction of alveoil due to toxins in cigarette smoke ( emphysema) leaky.
Airway resistance-
just as we saw with blood vessels the flow is inversly proportinal to resistance. Resistance is determined by the diameter of the airways. Sympathetic stimulation dialates the airways by relaxing the smmoth muscle (bronchodialation). COPD = chronic obstructive pulmonary disease, emphysema or chronic bronchitis.
Types of breathing-
eupena- normal quiet breathing dyspnea- difficult breathing apena- lack of breathing, not breathing costal breathin- shallow breathing diaphragmic- deep belly breathing
Lung volumes and capacities-
tidal volume- the volume of air that moves in and out of the lungs in a normal breath.
spirometer- instrument used to measure respiratory volumes.
Anatomical dead space - the space within the conducting structures.
Physiological dead space - not functioning, dead lung tissue.
Minute volume-
the volume of air taken in or out in one minute
Alveolar ventilation rate-
volume of air that reaches the respiratory structures per minute.
IRV - inspiratory reserve volume
EVR - expiratory reserve volume
RV - residual volume
FEV - forced expiratory volume
IRV, inspiratory reserve volume- the amount of air that can still be inhaled after a tidal breath.
EVR, expiratory reserve volume - the amount of air that can still be exhaled after a tidal breath.
RV, residual volume- air that still remains after maximal exhalation.
FVE, forced expriatory volume per unit of time (usually in seconds)
Functional residual capacity = RV + ERV
Inspiratory capacity = TV + IRV
Vital capacity = IRV + TV + ERV
Total lung capacity = IRV + TV + ERV + RV
Alveolar ventilation rate - (AVR) is more accurate than minute volume because it subtracts the air that is not reaching the respiratory structures.
AVR = breaths/min X (TV- anatomical dead space)
