Variable affecting the efficiency of gas exchange in the alveolus - will be asked abt on the quiz
Oxyhemoglobin disassociation curve - may be questions on quiz
Overview
Respiration
can mean ventilation of the lungs (breathing) OR
use of oxygen in cellular metabolism
Functions of the respiratory system
Gas exchange: provides oxygen & CO2 exchange btw blood & air
Communication: serves for speech and other vocalization
Olfaction: sense of smell
Acid-Base balance: controls pH of the body fluid
Blood Pressure Regulation: help synthesize angiotensin II, a hormone that regulate BP
Platelet Production: half the blood platelets is made by megakaryocytes in the lungs
Blood and Lymph Flow: promote flow of lymph and venous blood bc breathing creates pressure gradients btw thorax & abdomen
Blood Filtration: filter small blood clots - preventing obstruction
Expulsion of abdominal contents: breath-holding & abdominal contraction help to expel abdominal contents during urination, defecation, & childbirth
Air flows along a dead-end pathway consisting essentially of bronchi β bronchioles β alveoli
Conducting zone: consisting of passage that serve only for airflow, essentially from nostrils through the major bronchioles
Respiratory Zone: consists of the alveoli and other gas-exchange regions of the distal airway
The Upper Respiratory Tract: nose through the larynx
The Lower Respiratory Tract: Trachea through the lungs
The Nose
Several functions: Warms, cleanses & humidifies inhaled air, detects oder, and serves as a resonating chamber that amplifies the voice
Nostrils or Nares: anterior openings
Posterior Nasal Apertures or choanae: posterior openings
Facial part of the nose is shaped by bone & Hyaline cartilage
Superior half is supported by a pair small nasal bones medially and the maxillae laterally.
The inferior half is supported by the lateral and alar cartilages
The flared portion on each side of the lower end of the nose called the ala nasi, shaped by the alar cartilages and dense connective tissue
Nasal Cavity - internal chamber of the nose
divides into right and left halves = nasal fossae
The dividing wall is a vertical plate called the nasal septum, which is composed of bone and hyaline cartilage
Vomer forms one-thrid
The perpendicular plate of the ethmoid forms the superior two thirds
Septal cartilage forms the non bony anterior part of the septum
Both the ethmoid & sphenoid compose the roof of the nasal cavity
paranasal sinuses and the nasolacrimal ducts of the orbit drain into the nasal cavity
Nasal cavity begins with a small dilated chamber called the vestibule just inside the nostril, bordered by the ala nasi
lined with stratified squamous epithelium, guard hairs, or vibrissae
Posterior to the vestibule, contained by three folds of tissue - the superior, middle, & inferior nasal conchae OR turbinates which project from the lateral walls toward the septum
Beneath each conchae are narrow air passages called a meatus
captures dust and air picks up moisture and heat from the mucosa - enables the the nose to cleanse, warm, & humidify the air more effectively
The Mucosa
consists of ciliated pseudostratified columnar epithelium
Over most the mucosa, the epithelium is called the respiratory epithelium
goblet cells, secrete most of the mucus
brush cells - chemosensory
cilia beta in waves and dust & debris stick to the mucus
nasal mucosa has olfactory epithelium - concerned with sense of smell
in the olfactory mucosa, the lamina propria has large serous olfactory glands
Lamina propia contains large blood vessels that help warm the air
erectile tissue (swell body) - located in the inferior concha
every 30 to 60 minutes the erectile tissue on one side swells &Y restricts airflow through that fossa - keeps the engorged side time to recover from drying
This is called the nasal cycle
The Pharynx
The pharynx is a muscular funnel extending from the posterior nasal apertures to the larynx
Contains three regions: Nasopharynx, Oropharynx, & laryngopharynx
The nasopharynx is distal to the posterior nasal apertures and superior to the soft palate - only passes air
The oropharynx is the space btw the posterior margin of the soft palate and the epiglottis - pass air, food, & drink
Laryngopharynx lies posterior to the larynx, extending from the superior margin of the epiglottis to the inferior margin of the cricoid cartilage - pass air, food, & drink
The Larynx
Larynx is cartilaginous chamber, primary function is to keep food & drink out of the airway, but has evolved the additional role of sound production - the voice box
superior opening guarded by the epiglottis
Consists of 9 cartilages
First three - solitary & relatively large
Most superior, epiglottic cartilage, spoon shaped supportive of elastic cartilage
The largest, thryoid cartilage, is shield-like, has anterior peak called the laryngeal prominence or the Adamβs Apple, constitute the voice box
Cricoid cartilage, most inferior, constitute the voice box
Remaining cartilage - smaller & occur in three pairs
Arytenoid cartilages: Two, Posterior to the thyroid cartilage, attached to their upper ends is a pair of little horns which are the corniculate cartilages
Cuneiform cartilages: supports the soft tissues btw the arytenoids and the epiglottis
Thyroid membrane: broad sheet suspends the larynx from the hyoid bone below it
Cricothyroid ligament suspends the cricoid cartilage from the thyroid cartilage
cricothyrotomy
Cricotracheal ligament suspends the trachea from the cricoid cartilage.
Contain two folds on each side
Vestibular folds - close larynx when swallowing
Vestibular ligaments - support the vestibular folds
Inferior vocal cords produce sounds when air passes btw them
contain vocal ligaments which are best suited to endure vibration and contact btw the cords
Vocal cords and the opening btw them are collectively called the glottis
The Trachea
Or windpipe, anterior to the esophagus, supported by 16 to 20 C-shaped rings of hyaline cartilage
These rings keep the trachea from collapsing when you inhale and create a partial vacuum in the airway
The open part of the C, where itβs spanned by a smooth muscle. the trachealis
Mucus in the trachea traps inhaled particles and the upward beat of the cilia drives the debris-laden mucus toward the pharynx, where it is swallowed - called the mucociliary escalator
outermost layer of the trachea - adventitia - blends with the adventitia of other organs of the mediastinum
Trachea ends at a fork called the tracheal bifurcation where it gives off right and left main bronchi - the lowermost tracheal cartilage has an internal median ridge called the carina
The Lungs and the Bronchial Tree
Broad costal surface is pressed against rib cage
mediastinal surface faces medially, toward the heart
The mediastinal surface exhibits a slit called the hilum through which the lung receives the main bronchus, blood vessels, & lymphatics, and nerves
These structures constitute the root of the lung
3 lobes of the lung nor are they symmetrical - right is shorter than the left
three lobes; superior, middle, & inferior
On the medial surface, the left lung has an indention called the cardiac impression part of the this is visible anteriorly as a crescent shaped cardiac notch
a deep groove called the horizontal fissure separates the superior & middle lobes, and a similar oblique fissure separates the middle and inferior lobes.
oblique fissure separates the middle and inferior lobes
the left lung has a only a superior and inferior lobe and a single oblique fissure
The Bronchial Tree
branching system of air tubes called the bronchial tree
right main bronchus extends from the fork
gives off three branches - the superior, middle & inferior lobar (secondary) bronchi - one to each lobe of the lung
left main bronchus - slightly narrower and less vertical than the right
gives off superior and inferior lobar bronchi to the two lobes of the left lung
in both lungs the lobar bronchi branch into segmental (tertiary) bronchi
each one ventilates a functionally independent unit of lung tissue called bronchopulmary segment
Bronchioles are continuations of the airway that lack supportive cartilage
The portion of the lung ventilated by one bronchioles is called a pulmonary lobule
each bronchiole divides into 50 to 80 terminal bronchioles - the final branches of the conducting zone
each terminal bronchiole gives off two or more smaller respiratory bronchioles - beginning of the respiratory zone bc their alveoli participate in gas exchange
these further divide into 2 to 10 aveolar ducts
these further divide into alveolar sacs, which are clusters of alveoli arrayed around a central space called the atrium
Alveoli
provide 70mΒ² of gas exchange surface per lung - equal to the floor area of an American indoor handball court or a room 8.4m (25ft) square
Alveolus is a pouch about 0.2 to 0.5 mm in diameter
clustered like soap bubbles & have pores in their walls that directly exchange air with each other
functions of alveolar cells: repair alveolar epithelium when the squamous cells are damaged and they secrete pulmonary surfactant - a mix of phospholipids and protein that coats the alveoli and small bronchioles and prevents the bronchioles from collapsing when one exhales
alveolar macrophages (dust cells) are the most numerous and keep the alveoli free of debris
the barrier btw the alveolar air and blood is called the respiratory membrane
Pulmonary Circulation
two blood supplies: pulmonary & systemic
Pulmonary circuit
begins with the pulmonary trunk arising form the RV.
the trunk then divides right and left pulmonary arteries which then divide into lobar arteries, which supply the three lobes of the right and two lobes of the left
Serves to only unload CO2 and pick up fresh O2 from inhalation
The oxygenated blood returns to the heart by way of pulmonary veins
Lungs receive systemic blood supply from the bronchial arteries that arise from the thoracic aorta
lead to pleura, bronchi, bronchioles, and the larger pulmonary blood vessels. DO NOT LEAD TO AhLVEOLI
Bronchial veins drain this blood from the lungs into the azygos vein of the thorax
The Pleurae
Serous membrane, the pleura, forms the surface of the lung
There are two layers - visceral and parietal
the visceral forms the surface and extends even. into the fissues btw the lobes
The parietal pleura, adheres to the mediastinum, inner surface of the rib cage, and the superior surface of the diaphragm
The space btw the parietal and visceral pleurae is called the pleural cavity
wraps around the lung
contains pleural fluid - only a potential space
Pleurae and pleural cavity have three functions
Reduction of friction: acts as lubricant that enables lungs to expand and contract with minimal friction - can cause pleurisy which makes breathing painful
Creation of a pressure gradient
Compartmentalization: The pleurae, mediastinum, and pericardium
, compartmentalize the thoracic organs and prevent infections of one organ from spreading easily to neighboring organs
Overview
Consists of a repetitive cycles of inspiration and expiration - one complete breathe (in and out) is called the respiratory cycle
Two kinds - quiet & forced
Quiet respiration refers to relaxes, unconscious, automatic breathing
Forced means usually deep or rapid breathing
Lungs do not ventilate themselves as they only contain smooth muscle
only adjusts the diameter of the airway and affects the speed of airflow
The Respiratory Muscles
Principle muscles are the diaphragm and intercostal muscles
Diaphragm is a prime mover; it alone produces abt two thirds of the pulmonary airflow
The diaphragm, at rest, is domed, and when contracting, move downward
Enlargement of the thoracic cavity lowers its internal pressure and produces an inflow of air
Other muscles aid the diaphragm as synergists
internal and external intercostal muscles btw the ribs
primary function is to keep the chest form moving inward
The scalene muscles (of neck ribs 1 & 2; holding them stationary)
attach to the first rib and can pull upward during quiet breathing
and can pull upwards like the handle on a bucket and enlarge the chest laterally & anteriorly
Accessory muscles