Question | Answer |
Main Functions of the Respiratory System | Its an organ system the rhythmically takes in air and expels it from the body, thereby |
Main Functions of the Respiratory System | It provides oxygen and carbon dioxide exchange between the blood and air. |
Main Functions of the Respiratory System | It serves for speech and other vocalizations such as crying and laughing. |
Main Functions of the Respiratory System | It provides the sense of smell |
Main Functions of the Respiratory System | By eliminating CO2, it helps control the pH of the body fluids.Therefore if the respiratory system does not keep pace with the rate of CO2 |
Main Functions of the Respiratory System | The lungs carry out a step in the synthesis of a vasoconstrictor called Angiotensin II, |
Main Functions of the Respiratory System | Breathing creates pressure gradients b/w the thorax and abdomen that permit the flow |
Two Main Divisions of the Respiratory System | Conducting Division & Respiratory Division |
Conducting Division | This division consists of those passages that serve only for airflow – basically from the |
Respiratory Division | This division consists of the alveoli and other distal gas exchange areas. |
The main functions of the nose | a)Warms, cleanses and humidifies inhaled air.
b)Detects odors in the airstream.
c)Serves as a resonationg chamber that amplifies the voice. |
Basic Anatomy of the Nose | It extends from a pair of anterior openings called the nostrils or anterior (external) |
Basic Anatomy of the Nose | The facial part of the nose is shaped by bone and hyaline cartilage |
The nasal cavity | This is the internal chamber of the nose which is divided into right and left halves |
Three parts to the nasal septum | (a) Superior Part – formed by the perpendicular plate of the ethmoid bone.
(b) Inferior Part – formed by the vomer
(c) Anterior Part – formed by the septal cartilage |
ethmoid and sphenoid bones | compose the roof of the nasal cavity and the palate |
nasal cavity | The nasal cavity begins with a small dilated chamber called the vestibule, just inside
the nostril. |
nasal cavity | This space is lined w/ stratified squamous epithelium and has stiff guard hairs |
nasal cavity | These folds of tissue are the superior, middle and inferior nasal
conchae. |
nasal cavity | Odors are detected by sensory cells in the olfactory mucosa – a small patch of |
Nasal Cavity | Lining the rest of the nasal cavity and extending deep into the lungs is a
psuedostratified respiratory mucosa. This is a nonsensory epithelium having two
types of cells: Goblet & Ciliated Cells |
Goblet cells | These produce mucus. |
Ciliated cells | In the nose, these cilia drive the mucus toward the posterior nares and into the |
Pharynx | The pharynx is a muscular funnel extending about 13 cm from the choanae to the |
Pharynx has three main regions | Nasopharynx, Oropharynx, Laryngopharynx |
Nasopharynx | This i)This part lies posterior to the choanae and dorsal to the soft palate.
ii)It receives the auditory tubes from the middle ears and contains the pharyngeal tonsil.
iii)Lined by pseudostratified columnar epithelium.
iv)The nasaopharynx passes only |
Oropharynx | ii)It contains the palatine and lingual tonsils.
iii)Lined by stratified squamous epithelium.
iv)Passes air, food and drink. |
Laryngopharynx | The esophagus begins at this point.
Lined by stratified squamous epithelium.
Passes air, food and drink. |
Larynx | The larynx (voicebox) is a cartilaginous chamber about 4 cm long. |
Main functions of the larynx | To keep food and drink out of the airway. / Sound production. |
Epiglottis | A flap of tissue which guards the superior opening of the larynx. |
Epiglottis | During swallowing, extrinsic muscles of the larynx pull the larynx upward toward |
Basic framework of the larynx consists of nine cartilages | i)Epiglottic Cartilage
ii)Thyroid Cartilage
iii)Cricoid Cartilage
iv)Arytenoid Cartilages (one pair)
v)Corniculate Cartilages (one pair)
vi)Cuneiform Cartilages (one pair) |
Epiglottic Cartilage | This is the most superior cartilage. It’s a spoon shaped supportive plate in the
epiglottis. |
Thyroid Cartilage | This is the largest cartilage and has a sheildlike shape. It broadly covers the
anterior/lateral aspects of the larynx. The laryngeal prominence is the anterior peak
of the thyroid cartilage – also called the Adam’s apple. |
Cricoid Cartilage | Found inferior to the thyroid cartilage. It connects the larynx to the trachea. |
Arytenoid Cartilages (one pair) | This pair of cartilages is found posterior to the thyroid cartilage. These cartilages
function in speech. |
Corniculate Cartilages (one pair) | These cartilages are found attached to the upper ends of the arytenoid cartilages.
These cartilages function in speech (along with the arytenoids cartilages). |
Cuneiform Cartilages (one pair) | This pair of cartilages support the soft tissues b/w the arytenoids cartilages and
epiglottis. |
Ligaments of the larynx | A group of fibrous ligaments bind the cartilages of the larynx together and to
adjacent structures in the neck. |
Extrinsic Ligaments | These are ligaments which link the larynx to other organs, namely:
a. Thyrohyoid ligament
b. Crichotracheal ligament |
Thyrohyoid ligament | Found superiorly, it’s a broad sheet that joins the thyroid cartilage to the hyoid |
Crichotracheal ligament | Found inferiorly, this ligament joins the cricoid cartilage to the trachea. |
Instrinsic Ligaments | They support the
vestibular folds and vocal cords. |
Extrinsic muscles | These connect the larynx to the hyoid bone and elevate the larynx during swallowing. |
Intrinsic muscles | These muscles control the vocal cords by pulling on the corniculate and arytenoids
cartilages, causing the cartilages to pivot. Depending on their direction of rotation,
the arytenoid cartilages abduct or adduct the vocal cords. Air forced b/w the
addu |
Folds of the Larynx | There are two folds found on each side of the interior wall of the larynx. They run
from the thyroid cartilage in front to the arythenoid cartilages in the back. |
Vestibular Folds | This is the superior pair. They close the glottis during swallowing but play no role
in speech. |
Vocal Folds (vocal cords) | a. Inferior pair of folds.
b. Produce sound when air passes through them. c. Contain vocal ligaments and covered w/ stratified squamous epithelium.
d. Vocal folds & opening b/w them are glottis |
Trachea | The trachea (windpipe) is a rigid tube about 12 cm long and 2.5 cm in diameter. |
Basic anatomy of the trachea | It lies anterior to the esophagus. |
Basic anatomy of the trachea | It is supported by 16 to 20 C shaped rings of hyaline cartilage. The posterior part of the trachea has open C rings. These openings are spanned by
the trachealis muscles. This opening in the cartilage allows for the esophagus to
expand, as swallowed foo |
Basic anatomy of the trachea | The posterior part of the trachea has open C rings. These openings are spanned by |
Basic anatomy of the trachea | The inner lining of the trachea is a pseudostratified columnar epithelium. This |
Basic anatomy of the trachea | The CT beneath the tracheal epithelium has lymphatic nodules, mucous and serious
glands and the tracheal cartilages. |
Basic anatomy of the trachea | The adventia is the outermost layer of the trachea. It is composed of fibrous CT that |
Basic anatomy of the trachea | At its inferior end, the trachea forks into right and left primary bronchi. The lowermost |
The Lungs | Each lung is a conical organ with a broad concave base resting on the diaphragm and a
blunt peak called the apex projecting slightly above the clavicle. |
Costal surface | This is the broad surface that is pressed against the rib cage. |
Mediastinal Surface | The smaller concave surface that faces medially. This surface has a slit called the |
Right Lung | Is shorter than the left lung because the liver rises higher on the right. |
Right Lung | The right lung has three lobes – superior, middle and inferior – which are
separated by two fissures. |
Left Lung | Although taller, this lung is more narrow than the right lung because the heart tilts
toward the left and occupies more space on this side of the mediastinum. |
Left Lung | Has only a superior and inferior lobe and a single fissure. |
Definition of the bronchial tree | A highly branched system of air tubes extending from the primary bronchus to about
65, 000 terminal bronchioles. |
Basic Anatomy of the Bronchial Tree | Two primary bronchi arise from the trachea at the level of the angle of the sternum. |
Basic Anatomy of the Bronchial Tree | Each secondary bronchus divides into tertiary bronchi. The part of the lung supplied |
Basic Anatomy of the Bronchial Tree | Bronchioles are continuations of the airway that lack supportive cartilage and are |
Basic Anatomy of the Bronchial Tree | Each bronchiole divides into 50 to 80 terminal bronchioles – the final branches of the |
Basic Anatomy of the Bronchial Tree | Each terminal bronchiole gives off two or more smaller respiratory bronchioles, |
Basic Anatomy of the Bronchial Tree | Each respiratory bronchiole divides into 2 to 10 elongated, thin walled passages
called alveolar ducts, which have alveoli along their walls. These ducts have
nonciliated simple squamous epithelium. The ducts end in alveolar sacs, which are
grapelike c |
Alveoli | An alveolus is a simple pouch about 0.2 to 0.5 mm in diameter. |
Squamous (type I) Alveolar Cells | Thin broad cells that cover about 95% of the alveolar surface. |
Squamous (type I) Alveolar Cells | Their thinness allows for rapid gas diffusion b/w the alveolus and bloodstream. |
Great (type II) Alveolar Cells | Cuboidal cells that cover 5 % of the alveolar surface. They outnumber the |
Great (type II) Alveolar Cells Function | Secrete pulmonary surfactant – which is a mixture of phospholip
protein that coats the alveoli/smallest bronchioles and prevents
from collapsing when one exhales. Without surfactant, the walls
deflating alveolus would cling together like sheets of wet |
Alveolar Macrophages | The most numerous off all lung cells. |
Respiratory Membrane | The barrier b/w the alveolar air and the blood. |
Respiratory Membrane | This membrane consists of the squamous alveolar cell, the squamous endothelial cell |
Neural Control of Breathing | The hearbeat and breathing are the two most obvious rhythmic processes in the body. |
Neural Control of Breathing | The heart has an internal pacemaker and continues beating – even if all the nerves to it |
Neural Control of Breathing | Conversely, the lungs have no autorhythmic pacemaker cells for respiration. The |
Breathing depends on repetitive stimuli from the brain | Breathing stops if the nerve connections to the thoracic muscles are severed or if the |
There are two reasons for this dependence on the brain | Skeletal muscles (unlike cardiac muscles), can’t contact without input from the |
There are two reasons for this dependence on the brain | Breathing involves the organized action of many muscles and thus requires a central |
Breathing is controlled at two levels of the brain | a)Cerebral/Conscious Control & Involuntary/Unconscious Control |
Cerebral/Conscious Control | This allows us to inhale/exhale at will. |
Brainstem Respiratory Centers | The involuntary/unconscious control of breathing is controlled by three respiratory |
Dorsal Respiratory Group (DRG) | This is an elongated mass of neurons, extending for most of the length of the |
Dorsal Respiratory Group (DRG) | The neurons here are called inspiratory (I) neurons because their firing stops
inhalation.
a. Their axons decussate and descend the contralateral spinal cord and end in
integrating centers of the cervical and thoracic spinal cord.
b. Lower motor neuro |
DRG output begins weakly and builds in intensity over a period of about 2 seconds | The inpiratory muscles contract w/ increasing force and we inhale. |
Ventral Respiratory Group (VRG) | This is another elongated neural network, just ventral to the DRG. |
Ventral Respiratory Group (VRG) | It consists of both I neurons and expiratory (E) neurons and is active during both |
Ventral Respiratory Group (VRG) | It shows little activity during quiet respiration but comes into play during heavy
breathing such as during exercise. |
Ventral Respiratory Group (VRG) | The VRG is especially important in stimulating the abdominal/other accessory |
Pneumotaxic Center | This is a nucleus in the pons that regulates the shift from inspiration to expiration. |
Central and Peripheral Input to the Respiratory Centers | Input from the hypothalamus and limbic system enables pain and emotion to affect
breathing – for example in gasping, crying and laughing. |
Central Chemoreceptors | These are brainstem neurons that respond to changes in the pH of the CSF. |
Peripheral Chemoreceptors | These are located in the aortic and carotid bodies of the large arteries above the heart. |
Peripheral Chemoreceptors | They respond to the concentration of O2/CO2 in the blood and to the pH of the blood. |
Irritant Receptors | These are nerve endings amid the epithelial cells of the airway. They respond to |
Irritant Receptors | They transmit signals by way of the vagus nerves to the DRG. In turn, the DRG |
Voluntary Control of Breathing | Voluntary control of breathing is important in singing, speaking, breath holding, etc. |
Voluntary Control of Breathing | This voluntary control originates from the motor cortex of the frontal lobe of the
cerebrum.
The output neurons send impulses down the corticospinal tracts to the integrating
centers in the spinal cord, bypassing the brainstem centers |
Gas Exchange and Transport | analyze how O2 is obtained from inspired air and delivered to the
tissues and how CO2 is removed from the tissues and released into the expired air. |
Composition of Air | Air consists of the following: 78.6% nitrogen, 20.9% oxygen, 0.04% CO2, 0 to 4%
water vapor and several minor gases such as argon, neon, helium, methane and ozone. |
Dalton’s Law | This law gives the total atmospheric pressure which is the sum of the contributions of
the gases mentioned above. |
Alveolar Gas Exchange | Alveolar gas exchange is the back and forth traffic of O2 and CO2 across the respiratory membrane. |
Alveolar Gas Exchange | The reason that oxygen can diffuse in one direction and carbon dioxide in the other is
that each gas diffused down its own pressure gradient. |
Henry’s Law | States that at the air-water interface for a given temperature, the amount of gas
that dissolves in the water is determined by its solubility in water and its partial
pressure in the air. |
Chemical Reactions in Alveolar Gas Exchange | The events of alveolar gas exchange are the opposite of systemic gas exchange. |
Pressure gradients of the gases | The P02 is about 104 mm Hg in the alveolar air and 40 mm Hg in the blood arriving |
Membrane thickness | The respiratory membrane b/w the blood and alveolar air is only 0.5 um thick – much
less than the 7 to 8 um diameter of a RBC. Thus, it presents little obstacle to
diffusion. |
Membrane thickness | in conditions such as left ventricular failure, blood pressure backs up into |
Membrane area | several pulmonary diseases such as emphysema, TB, lung cancer decrease
the alveolar surface area and thus result in low blood P02 |
Ventilation-perfusion coupling | The lungs have a ventilation-perfusion ratio of about 0.8 – a flow of 4.2 L of air and
5.5 L of blood per minute at rest. |
Primary Organs of the Respiration System | 1. Nose
2. Pharynx
3. Larynx
4. Trachea
5. Bronchi
6. Lungs |