A&P 22: The Respiratory System Flashcards
Respiratory System
system that supplies the body with oxygen and disposes of carbon dioxide
Respiration
pulmonary ventilation, external respiration, transport of respiratory gases, and internal respiration are collectively known as this function
Pulmonary ventilation
breathing; air moving in and out of the lungs (during inspiration and expiration) so the gases there are continuously changed and refreshed
External respiration
oxygen diffuses from the lungs to the blood, and carbon dioxide diffuses from the blood to the lungs
Transport of respiratory gases
oxygen is transported from the lungs to the tissue cells of the body, and carbon dioxide is transported from the tissue cells to the lungs; the cardiovascular system accomplishes this transport using blood as the transporting fluid
Internal respiration
oxygen diffuses from blood to tissue cells, and carbon dioxide diffuses from tissue cells to blood
Respiratory zone
actual site of gas exchange; composed of the respiratory bronchioles, alveolar ducts, and alveoli, all microscopic structures
Conducting zone
includes all other respiratory passageways, which provide fairly rigid conduits for air to reach the gas exchange sites
Nostrils (nares)
external openings of the nose
Nasal cavity
internal cavity lying in and posterior to the external nose
Nasal septum
the nasal cavity is divided by this midline, formed anteriorly by the septal cartilage and posteriorly by the vomer bone and perpendicular plate of the ethmoid bone
Posterior nasal apertures
the nasal cavity is continuous posteriorly with the nasal portion of the pharynx through these “funnels” called choanae
Hard palate
where the palate is supported by the palatine bones and processes of the maxillary bones
Soft palate
the unsupported posterior portion is this muscular palate
Nasal vestibule
part of the nasal cavity just superior to the nostrils; lined with skin containing sebaceous and sweat glands and numerous hair follicles
Vibrissae
nose hairs; filter coarse particles from inspired air
Olfactory mucosa
small patch of this lines the slitlike superior region of the nasal cavity and contains smell receptors in its olfactory epithelium
Olfactory epithelium
where smell receptors are contained
Respiratory mucosa
lines most of the nasal cavity; pseudostratified ciliated columnar epithelium, containing scattered goblet cells, that rests on a lamina propia richly supplied with seromucous nasal glands
Paranasal sinuses
the nasal cavity is surrounded by a ring of these chambers; located in the frontal, sphenoid, ethmoid, and maxillary bones
Sinusitis
inflamed sinuses
Pharynx
funnel-shaped organ that connects the nasal cavity and the mouth superiorly to the larynx and esophagus inferiorly
Nasopharynx
posterior to the nasal cavity, inferior to the sphenoid bone, superior to the level of the soft palate; part of the pharynx serving only as an air passageway
Pharyngeal tonsil
AKA adenoids; traps and destroys pathogens entering the nasopharynx in air
Oropharynx
part of the pharynx lying posterior to the oral cavity & continuous with it through an archway (isthmus of fauces)
Isthmus of fauces
archway continuous with the oropharynx
Palatine tonsils
paired tonsils embedded in the lateral walls of the oropharyngeal mucosa just posterior to the oral cavity
Lingual tonsil
tonsil covering the posterior surface of the tongue
Laryngopharynx
serves as a passageway for food and air; lined with a stratified squamous epithelium; directly posterior to the upright epiglottis and extends to the larynx, where the respiratory and digestive pathways diverge
Larynx
voice box; extends for 5cm from the level of the 3rd to the 6th cervical vertebra
Thyroid cartilage
large, shield-shaped cartilage formed by the fusion of 2 cartilage plates
Laryngeal prominence
midline; marks the fusion point of 2 cartilage plates; obvious externally as the Adam’s Apple
Cricoid cartilage
ring-shaped cartilage perched atop and anchored to the trachea inferiorly
Arytenoid, cuneiform, & corniculate cartilages
3 pairs of small cartilages that form part of the lateral and posterior walls of the larynx
Epiglottis
9th cartilage; flexible, spoon-shaped structure; composed of elastic cartilage and is almost entirely covered by a taste bud-containing mucosa
Vocal ligaments
ligaments that attach they arytenoid cartilages to the thyroid cartilage; composed largely of elastic fibers; form the core of mucosal folds (vocal cords)
Vocal folds (true vocal cords)
mucosal folds, appear pearly white because they lack blood vessels; vibrate, producing sounds as air rushes up from the lungs
Glottis
the vocal folds and the medial openings between them through which air passes
Vestibular folds (false vocal cords)
superior to the vocal folds is a similar pair of mucosal folds; play no direct part in sound production but help to close the glottis when we swallow
Laryngitis
inflammation of the vocal folds
Valsalva’s Maneuver
the vocal folds acting as a sphincter that prevents air passage; during abdominal straining associated with defecation, the glottis closes to prevent exhalation and the abdominal muscles contract, causing the intra-abdominal pressure to rise; these events help empty the rectum and can also splint/stabilize the body trunk when lifting a heavy load
Trachea
windpipe; descends from the larynx through the neck and into the mediastinum; ends by dividing into the 2 main bronchi at midthorax
Submucosa
connective tissue layer deep to the mucosa containing seromucous glands that help produce the mucus sheets within the trachea
Adventitia
outermost layer of connective tissue of the trachea
Trachealis
the open posterior parts of the cartilage rings of the trachea, which abut the esophagus; connected by smooth muscle fibers of this & by soft connective tissue
Carina
spar of cartilage as the last tracheal cartilage is expanded; projects posteriorly from the inner face of the trachea; marks the point where the trachea branches into 2 main bronchi
Heimlich maneuver
procedure in which air in the victim’s lungs is used to expel an obstructing piece of food
Bronchial tree
the air passageways in the lungs branch again and again (about 23 times overall) in a pattern called this
Right and left (primary) bronchi
the trachea divides to form these passageways; approximately at the level of T7 in an erect/standing person
Lobar (secondary) bronchi
once inside the lungs, each main bronchus subdivides into these passageways, 3 on the right and 2 on the left, each supplying one lung lobe
Segmental (tertiary) bronchi
the lobar bronchi branch into 3rd order segments, which divide repeatedly into smaller and smaller bronchi
Bronchioles
passages smaller than 1mm in diameter
Terminal bronchioles
smallest of the passages in the lungs; less than 0.5mm in diameter
Alveoli
thin-walled air sacs
Respiratory bronchioles
the respiratory zone begins as the terminal bronchioles feed into these passages within the lungs
Alveolar ducts
the respiratory bronchioles lead into these winding ducts, whose walls consist of diffusely arranged rings of smooth muscle cells, connective tissue fibers, and outpocketing alveoli
Alveolar sacs/saccules
the alveolar ducts lead into these terminal clusters of alveoli
Type I alveolar cells
the walls of the alveoli are composed primarily of as single layer of these squamous epithelial cells, surrounded by a flimsy basement membrane
Respiratory membrane
the capillary and alveolar walls and their fused basement membranes form this 0.5 micrometer thick blood air barrier that has blood flowing past on 1 side and gas on the other
Type II alveolar cells
cells that secrete a fluid containing a detergent-like substance called surfactant that coats the gas-exposed alveolar surfaces
Alveolar pores
openings connecting adjacent alveoli that allow air pressure throughout the lung to be equalized and provide alternate air routes to any alveoli whose bronchi have collapsed due to disease
Alveolar macrophages
phagocytes that crawl freely along the internal alveolar surfaces
Lungs
pair of structures that occupy all of the thoracic cavity except the mediastinum, which houses the heart, great blood vessels, bronchi, esophagus, and other organs
Root
each cone-shaped lung is surrounded by pleurae and connected to the mediastinum by vascular & bronchial attachments, collectively called this
Costal surface
the anterior, lateral, and posterior lung surfaces lie in close contact with the ribs and form this continuously curving surface
Apex
narrow superior tip of the lung, just deep to the clavicle
Base
concave, inferior surface of the lung that rests on the diaphragm
Hilum
on the mediastinal surface of each lung is this indentation through which pulmonary and systemic blood vessels, bronchi, lymphatic vessels, and nerves enter and leave the lungs
Cardiac notch
concavity in the medial aspect of the left lung to make room for the heart
Lobes
subdivisions of each lung; 3 on the right; 2 on the left
Bronchopulmonary segments
each lobe contains a number of these pyramid-shaped segments separated from one another by connective tissue septa
Lobules
the smallest subdivisions of the lung visible with the naked eye; appear at the lung surface as hexagons ranging from the size of a pencil eraser to the size of a penny
Stroma
elastic connective tissue that makes up the majority of the lungs
Pulmonary arteries
systemic venous blood that is to be oxygenated in the lungs is delivered by these vessels which lie anterior to the main bronchi
Pulmonary capillary networks
in the lungs, the pulmonary arteries branch profusely along with the bronchi and finally feed into these networks surrounding the alveoli
Pulmonary veins
vessels conveying the freshly oxygenated blood from the respiratory zone of the lungs to the heart
Bronchial arteries
provide oxygenated systemic blood to lung tissue; arise from the aorta, enter the lungs as the hilum, and then run along the branching bronchi
Pulmonary plexus
the lungs are innervated by parasympathetic and sympathetic motor fibers, and visceral sensory fibers that enter each lung through this plexus on the lung root and run along the bronchial tubes and blood vessels in the lungs
Pleurae
form a thin, double-layered serosa
Parietal pleura
layer covering the thoracic wall and superior face of the diaphragm
Visceral pleura
layer covering the external lung surface, dipping into and lining its fissures
Pleural fluid
fluid filling the slitlike pleural cavity between the pleurae
Pleurisy
inflammation of the pleurae, often from pneumonia
Breathing
pulmonary ventilation; consists of 2 phases - inspiration & expiration
Inspiration
period when air flows into the lungs
Expiration
period when gases exit the lungs
Atmospheric pressure (Patm)
pressure exerted by the air (gases) surrounding the body; 760mm Hg at sea level
Intrapulmonary pressure (Ppul)
pressure in the alveoli
Intrapleural pressure (Pip)
pressure in the pleural cavity
Transpulmonary pressure
difference between the intrapulmonary & intrapleural pressures that keeps the air spaces of the lungs open (or keeps the lungs from collapsing)
Atelectasis
lung collapse; occurs when a bronchiole becomes plugged (as may follow pneumonia)
Pneumothorax
presence of air in the pleural cavity; reversed by drawing air out of the intrapleural space with chest tubes
Boyle’s Law
law giving the relationship between the pressure and volume of a gas: at constant temperature, the pressure of a gas varies inversely with its volume; p1vi = p2v2
Inspiratory muscles
diaphragm and external intercostal muscles
Surface tension
state of tension at the surface of a liquid
Surfactant
detergent-like complex of lipids and proteins produced by the type II alveolar cells; decreases the cohesiveness of water molecules
Infant respiratory distress syndrome (IRDS)
condition in which too little surfactant is present, surface tension can collapse the alveoli
Lung compliance
distensibility of lungs (unbelievably stretchy)
Respiratory volumes
tidal, inspiratory reserve, expiratory reserve, and residual
Tidal volume (TV)
respiratory volume during normal quiet breathing, about 500 mL of air moves into and then out of the lungs with each breath
Inspiratory reserve volume (IRV)
amount of air that can be inspired forcibly beyond the tidal volume
Expiratory reserve volume (ERV)
amount of air (normally 1000-1200mL) that can be expelled from the lungs after a normal tidal volume expiration
Residual volume (RV)
even after the most strenuous expiration, about 1200mL of air remains in the lungs; helps to keep the alveoli patent (open) and prevent lung collapse
Respiratory capacities
inspiratory, functional residual, vital, and total lung capacities
Inspiratory capacity (IC)
total amount of air that can be inspired after a normal tidal volume expiration (sum of TV & IRV)
Functional residual capacity (FRC)
amount of air remaining in the lungs after a normal tidal volume expiration (RV + ERV)
Vital capacity (VC)
total amount of exchangeable air; sum of TV, IRV, & ERV; ~4800 mL in healthy young males
Total lung capacity (TLC)
sum of all lung volumes; normally ~ 6000 mL
Anatomical dead space
volume of conducting zone conduits that never contribute to gas exchange; typically amounts to 150mL; in a healthy young adult = 1mL per pound of ideal body weight
Alveolar dead space
if some alveoli cease to act in gas exchange (due to alveolar collapse or obstruction by mucus), this volume is added to the anatomical dead space
Total dead space
sum of the nonuseful volumes (anatomical and alveolar dead space)
Spirometer
original clinical measuring tool for lung volumes and capacities
Forced vital capacity (FVC)
amount of gas expelled when a subject takes a deep breath and then forcefully exhales maximally and as rapidly as possible
Forced expiratory volume (FEV)
determines the amount of air expelled during specific time intervals of the FVC test
Minute ventilation
total amount of gas that flows into or out of the respiratory tract in 1 minute
Alveolar ventilation rate (AVR)
better index of effective ventilation (compared to minute ventilation); takes into account the volume of air wasted in the dead space and measures the flow of fresh gases in and out of the alveoli during a particular time interval; = frequency (breaths/min) x (TV - dead space)
Nonrespiratory air movements
processes other than breathing; most result from reflex activity, but some are produced voluntarily
Dalton’s Law of Partial Pressures
law stating that the total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture
Partial pressure
pressure exerted by each gas in a mixture
Henry’s Law
law stating that when a gas is in contact with a liquid, the gas will dissolve in the liquid in proportion to its partial pressure
Oxygen toxicity
condition that develops rapidly when PO2 is greater than 2.5-3 atm
Oxyhemoglobin (HbO2)
the hemoglobin-oxygen combination
Reduced hemoglobin
hemoglobin that has released oxygen; AKA deoxyhemoglobin (HHb)
Oxygen-hemoglobin dissociation curve
graph showing how local PO2 controls oxygen loading and unloading from hemoglobin
Bohr Effect
both declining blood pH (acidosis) and increasing PCO2 weaken the Hb-O2 bond, a phenomenon called this; enhances oxygen unloading where it is most needed
Hypoxia
inadequate oxygen delivery to body tissues
Anemic hypoxia
reflects poor O2 delivery resulting from too few RBCs or from RBCs that contain abnormal or too little Hb
Ischemic (stagnant) hypoxia
results from impaired or blocked blood circulation
Histotoxic hypoxia
occurs when body cells are unable to use O2, even though adequate amounts are delivered; metabolic poisons, such as cyanide, can cause this
Hypoxemic hypoxia
indicated by reduced arterial PO2; possible causes include disordered or abnormal ventilation-perfusion coupling, pulmonary diseases that impair ventilation, and breathing AC containing scant amounts of O2
Carbon monoxide poisoning
unique type of hypoxemic hypoxia; leading cause of death from fire
Carbaminohemoglobin
dissolved CO2 is bound and carried in the RBCs
Bicarbonate ions (HCO3-)
most carbon dioxide molecules entering the plasma quickly enter RBCs, where the reactions that prepare carbon dioxide transport as these ions in plasma mostly occur
Carbonic anhydrase
substance in RBCs; enzyme that reversibly catalyzes the conversion of carbon dioxide and water to carbonic acid
Chloride shift
to counterbalance the rapid outrush of these anions from the RBCs, chloride ions move from the plasma into the RBCs; this ion exchange process occurs via facilitated diffusion through a RBC membrane protein
Haldane Effect
the lower PO2 and the lower the Hb saturation with oxygen, the more CO2 the blood can carry; reflects the greater ability of reduced hemoglobin to form carbaminohemoglobin and to buffer H+ by combining with it
Carbonic acid-bicarbonate buffer system
very important in resisting shifts in blood pH
Ventral respiratory group (VRG)
network of neurons that extends in the ventral brain stem from the spinal cord to the pons-medulla junction
Dorsal respiratory group (DRG)
located dorsally near the root of cranial nerve IX
Phrenic and intercostal nerves
2 nerves exciting the diaphragm and external intercostal muscles
Eupnea
normal respiratory rate and rhythm
Pontine respiratory group
transmit impulses to the VRG of the medulla
Chemoreceptors
sensors responding to chemical fluctuations
Central chemoreceptors
receptors located throughout the brain stem, including the ventrolateral medulla
Peripheral chemoreceptors
receptors found in the aortic arch and carotid arteries
Hypercapnia
condition in which CO2 accumulates in the brain
Hyperventilation
increase in the rate and depth of breathing that exceeds to body’s need to remove CO2
Hypocapnia
low CO2 levels in the blood
Apnea
breathing cessation
Aortic bodies
where peripheral chemoreceptors can be found in the aortic arch
Carotid bodies
where peripheral chemoreceptors can be found (in addition to the aortic arch)
Hering-Breuer Reflex
inflation reflex
Hyperpnea
increased ventilation in response to metabolic needs
Acclimatization
when you move on a long-term basis from sea level to the mountains, your body makes respiratory and hematopoietic adjustments via this adaptive response
Chronic obstructive pulmonary diseases (COPD)
diseases exemplified best by emphysema and chronic bronchitis
Dyspnea
difficult or labored breathing often referred to as “air hunger”
Hypoventilation
most COPD victims develop respiratory failure manifested as this insufficient ventilation in relations to metabolic needs, causing them to retain CO2, respiratory acidosis, and hypoxemia
Emphysema
distinguished by permanent enlargement of the alveoli, accompanied by destruction of the alveolar walls
Chronic bronchitis
condition in which inhaled irritants lead to chronic production of excessive mucus
Asthma
condition characterized by episodes of coughing, dyspnea, wheezing, and chest tightness
Tuberculosis (TB)
infectious disease caused by the bacterium Mycobacterium tuberculosis; spread by coughing and primarily enters the body in inhaled air
Adenocarcinoma
40% of lung cancer cases, which originates in peripheral lung areas as solitary nodules that develop from bronchial glands and alveolar cells
Squamous cell carcinoma
25-30% of lung cancer cases; which arises in the epithelium of the bronchi or their larger subdivisions and tends to form masses that may cavitate (hollow out) and bleed
Small cell carcinoma
20% of lung cancer cases; round lymphocyte-sized cells that originate in the main bronchi and grow aggressively in small grapelike clusters within the mediastinum
Olfactory placodes
2 thickened plates of ectoderm present on the anterior aspect of the head
Olfactory pits
olfactory placodes invaginate to form these structures that form the nasal cavities
Laryngotracheal bud
the epithelium of the lower respiratory organs develops as an outpocketing of the foregut endoderm, which becomes the pharyngeal mucosa; this protrusion is present by the 5th week of development
Cystic fibrosis (CF)
most common lethal genetic disease in North America; strikes 1 in 2400 births
