Bio 233 @ Oit - Unit 2

Front 1

Describe the respiratory and conductions zones of respiratory system

Back 1

Respiratory System consists of the respiratory and conducting zones. Respiratory zone is
a site of gas exchange; it consists of bronchioles, alveolar ducts, and alveoli. Conducting
zone provides rigid conduits for air to reach the sites of gas exchange. It includes all
other respiratory structures (e.g., nose, nasal cavity, pharynx, and trachea)

Front 2

List the functions of respiratory system

Back 2

Major function of the
respiratory system is to supply the body with oxygen and dispose of carbon dioxide

Front 3

Describe the functions of the nasal mucosa and conchae

Back 3

Olfactory mucosa lines the superior nasal cavity. Respiratory mucosa lines the rest of the nasal cavity. Its glands secrete mucus containing lysozyme and defensins to help destroy bacteria. Superior, medial, and inferior conchae protrude medially from the lateral walls and increase mucosal area.
They enhance air turbulence and help filter air. Their sensitive mucosa triggers sneezing when stimulated by irritating particles. During inhalation the conchae and nasal mucosa
filter, heat, and moisten air; during exhalation these structures reclaim heat and moisture and minimize heat and moisture loss.

Front 4

Study the anatomy of nose, pharynx, and larynx

Back 4

The nose is divided into two regions: the external nose and the internal nasal cavity.
External Nose includes: the root, the bridge, dorsum nasi, apex, nasal alae, the external
nares (nostrils). Philtrum is a shallow vertical groove inferior to the apex.
Internal Nose: nasal cavity lies in and posterior to the external nose. It is divided by a
midline nasal septum and opens posteriorly into the nasal pharynx via internal nares.
Vestibule of nasal cavity is a space immediately superior to the nares. It contains nasal
hairs that filter coarse particles from inspired air
Pharynx is a funnel-shaped tube of skeletal muscle that connects to the nasal cavity and
mouth superiorly, and larynx and esophagus inferiorly. It extends from the base of the
skull to the level of C6
Pharynx is divided into three regions, nasopharynx, oropharynx, and laryngopharynx.
Larynx attaches to the hyoid bone and opens into the laryngopharynx superiorly and continuous
with the trachea inferiorly. The three functions of the larynx are:
o To provide a patent airway
o To act as a switching mechanism to route air and food into the proper channels
o To function in voice production

Front 5

Describe the vocal production of speech and pitch/loudness of sound

Back 5

Speech is formed when expired air is released while opening and closing the glottis. Pitch is determined by the length and tension of the vocal cords; and loudness depends upon the force at which the air rushes across the vocal cords. The pharynx resonates, amplifies, and enhances sound quality. Sound is “shaped” into language by action of the pharynx, tongue, soft palate, and lip

Front 6

Describe Valsalva’s maneuver

Back 6

Valsalva’s maneuver, when air is temporarily held in the lower respiratory tract by closing the glottis causing intra-abdominal pressure to rise when abdominal muscles contract. Valsalva maneuver helps to empty the rectum and acts as a splint to stabilize the trunk when lifting heavy loads.

Front 7

List three layers which compose the wall the trachea

Back 7

Adventitia – outermost layer made of C-shaped rings of hyaline cartilage
The carina of the last tracheal cartilage marks the end of the trachea and the beginning of the right and left bronchi Air reaching the main (first degree) bronchi is warm and cleansed of impurities and is saturated with water vapor
Mucosa – made up of goblet cells and ciliated epithelium
o Submucosa – connective tissue deep to the mucosa
Glottis

Front 8

Describe the branching patterns of bronchi, and structural changes as conducting tubes become smaller

Back 8

Bronchi
Main right and left bronchi subdivide into secondary bronchi, each supplying a lobe of the lungs.
Air passages undergo 23 orders of branching in the lungs.
Tissue walls of bronchi mimic that of the trachea. As conducting tubes become smaller, structural changes occur: cartilage support structures and epithelium types change, and the amount of smooth muscle increases. Bronchioles consist of cuboidal epithelium and contain a complete layer of circular smooth muscle. They lack cartilage support and mucus-producing cells.

Front 9

List the features of bronchioles

Back 9

Bronchioles consist of cuboidal epithelium and contain a
complete layer of circular smooth muscle. They lack cartilage support and mucus-producing cells.

Front 10

List and describe the components of respiratory membrane and describe how it
can be served as an air-blood barrier

Back 10

External Respiration is a pulmonary gas exchange. Factors that influence the movement of oxygen and carbon dioxide across the respiratory membrane include:
o Structure of the respiratory membrane
Respiratory zone is composed of terminal bronchiole and adjacent alveoli. There are
approximately 300 million alveoli, they account for most of the lungs’ volume.
Alveoli provide tremendous surface area for gas exchange. Alveolar epithelium consists of three types of cells:
o Type I cells are thin squamous cells that line most of the surface (95%) and
permit gas exchange by simple diffusion. They also secrete angiotensin
converting enzyme (ACE)
o Type II Cells are simple cuboidal cells. They tend to be concentrate at septal junctions. Their function is to secrete surfactant
o Macrophages
Gas exchange occurs across the thin respiratory membrane. It is composed of alveolar and capillary walls and their fused basal laminas

Front 11

Identify anatomical landmarks of lung

Back 11

Lungs occupy the entire thoracic cavity except
the mediastinum. They have:
o Hilus – indentation that contains pulmonary and systemic blood vessels
o Root – vessels and bronchi that enter through the hilus
o Costal surfaces – anterior, lateral, and posterior surfaces in contact with the ribs
o Apex – narrow superior tip
o Base – inferior surface that rests on the diaphragm
Cardiac notch (impression) is a cavity that accommodates the heart. Left lung is separated into upper and lower lobes by the oblique fissure. Right lung is separated into three lobes
by the oblique and horizontal fissures. There are 10 bronchopulmonary segments in each lung.

Front 12

Describe and compare pulmonary and bronchial circulations

Back 12

Lungs are perfused by two circulations: pulmonary and bronchial:
o Pulmonary arteries supply systemic venous blood to be oxygenated. They branch profusely,
along with bronchi and ultimately feed into the pulmonary capillary network surrounding the
alveoli. Pulmonary veins carry oxygenated blood from respiratory zones to the heart
o Bronchial arteries provide systemic blood to the lung tissue. They arise from aorta and enter
the lungs at the hilus and supply all lung tissue except the alveoli. Bronchial veins
anastomose with pulmonary veins. Pulmonary veins carry most venous blood back to the
heart

Front 13

Understand the relationship between parietal pleura and visceral pleura

Back 13

Pleura is a thin, double-layered serosa. Parietal pleura covers the thoracic wall and superior face of the diaphragm, and continues around heart and between lungs. Visceral, or pulmonary, pleura covers the external lung surface and divides the thoracic cavity into three chambers: the central mediastinum, and two lateral compartments, each containing a lung

Front 14

Describe two phases of breathing (pulmonary ventilation)

Back 14

Pulmonary ventilation is a mechanical process that depends on volume changes in the thoracic
cavity. Volume changes lead to pressure changes, which lead to the flow of gases to equalize
pressure. Boyle’s Law describes the relationship between the pressure and volume of gases:
P1V1 = P2V2
(where P is pressure of a gas in mmHg, v is volume of a gas in mm3
, and subscripts 1 and 2
represent the initial and resulting conditions, respectively)

Breathing, or pulmonary ventilation, consists of two phases:
o Inspiration – air flows into the lungs
o Expiration – gases exit the lungs

Front 15

Define atmospheric, intrapulmonary, intrapleural, transpulmonary pressures, and
their relationships in the thoracic cavity

Back 15

Pressure Relationships in the Thoracic Cavity
Respiratory pressure is always described relative to atmospheric pressure. Atmospheric pressure
(Patm) is a pressure exerted by the air surrounding the body. Negative respiratory pressure is
simply the pressure that is less than Patm. Positive respiratory pressure is greater than Patm.
Intrapulmonary pressure (Ppul) is defined as the pressure within the alveoli. Intrapleural pressure
(Pip) is the pressure within the pleural cavity. Intrapulmonary pressure and intrapleural pressure
fluctuate with the phases of breathing. Intrapulmonary pressure always eventually equalizes
itself with atmospheric pressure. Intrapleural pressure is always negative (less than
intrapulmonary pressure and atmospheric pressure) due to surface tension of alveoli, elasticity of
the lung and elasticity of chest. Two forces act to pull the lungs away from the thoracic wall,
promoting lung collapse: elasticity of lungs causes them to assume smallest possible size; and
surface tension of alveolar fluid draws alveoli to their smallest possible size. An opposing force
is the elasticity of the chest wall that pulls the thorax outward to enlarge the lungs. Negative
intrapleural pressure acts as suction to keep lungs inflated: as thoracic wall moves outward
during inspiration, the intrapleural pressure becomes even more negative; as the thoracic wall
recoils during expiration, the pressure returns to -4mmHG (756mmHg).

Front 16

List two forces which cause lung collapse. Describe they are opposed in the thorax

Back 16

Two forces act to pull the lungs away from the thoracic wall,
promoting lung collapse: elasticity of lungs causes them to assume smallest possible size; and
surface tension of alveolar fluid draws alveoli to their smallest possible size. An opposing force
is the elasticity of the chest wall that pulls the thorax outward to enlarge the lungs. Negative
intrapleural pressure acts as suction to keep lungs inflated: as thoracic wall moves outward
during inspiration, the intrapleural pressure becomes even more negative; as the thoracic wall
recoils during expiration, the pressure returns to -4mmHG (756mmHg).

Front 17

Describe Boyle’s law and its implication in interpreting pulmonary ventilation

Back 17

Boyle’s Law describes the relationship between the pressure and volume of gases:
P1V1 = P2V2
(where P is pressure of a gas in mmHg, v is volume of a gas in mm3
, and subscripts 1 and 2
represent the initial and resulting conditions, respectively)

Front 18

Describe how airway resistance, alveolar surface, and lung compliance can be
physical factors influencing ventilation

Back 18

The relationship between flow (Q), pressure (P), and resistance (R) is:
Q = P/R
Resistance increases when smooth muscles of the medium and small size bronchioles constrict.
This causes decrease of the air flow.
Lung Compliance (the ease with which lungs can be expanded) also affects the air flow. It is determined by two main factors:
o Distensibility of the lung tissue and surrounding thoracic cage
o Surface tension of the alveoli
Respiratory Volumes and Capacities
o Tidal volume (TV) – air that moves into and out of the lungs with each breath (approximately 500 ml)
o Inspiratory reserve volume (IRV) – air that can be inspired forcibly beyond the tidal volume (2100–
3200 ml)
o Expiratory reserve volume (ERV) – air that can be evacuated from the lungs after a tidal expiration (1000–1200 ml)
o Residual volume (RV) – air left in the lungs after strenuous expiration (1200 ml)
o Inspiratory capacity (IC) – total amount of air that can be inspired after a tidal expiration (IRV + TV)
o Functional residual capacity (FRC)
– amount of air remaining in the lungs after a tidal expiration (RV + ERV)
o Vital capacity (VC) – the total amount of exchangeable air (TV + IRV + ERV)
o Total lung capacity (TLC) – sum of all lung volumes (approximately 6000 ml in males)

Front 19

Define respiratory volumes: tidal volume, inspiratory reserve volume, expiratory volume, and residual volume

Back 19

The relationship between flow (Q), pressure (P), and resistance (R) is:
Q = P/R
Resistance increases when smooth muscles of the medium and small size bronchioles constrict.
This causes decrease of the air flow.
Lung Compliance (the ease with which lungs can be expanded) also affects the air flow. It is
determined by two main factors:
o Distensibility of the lung tissue and surrounding thoracic cage
o Surface tension of the alveoli

Respiratory Volumes and Capacities
o Tidal volume (TV) – air that moves
into and out of the lungs with each
breath (approximately 500 ml)
o Inspiratory reserve volume (IRV) –
air that can be inspired forcibly
beyond the tidal volume (2100–
3200 ml)
o Expiratory reserve volume (ERV)
– air that can be evacuated from
the lungs after a tidal expiration
(1000–1200 ml)
o Residual volume (RV) – air left in
the lungs after strenuous expiration
(1200 ml)
o Inspiratory capacity (IC) – total
amount of air that can be inspired
after a tidal expiration (IRV + TV)
o Functional residual capacity (FRC)
– amount of air remaining in the lungs after a tidal expiration (RV + ERV)
o Vital capacity (VC) – the total amount of exchangeable air (TV + IRV + ERV)
o Total lung capacity (TLC) – sum of all lung volumes (approximately 6000 ml in males)

Front 20

Define respiratory capacities: inspiratory capacities, functional residual capacity,
total capacity, and total lung capacity

Back 20

The relationship between flow (Q), pressure (P), and resistance (R) is:
Q = P/R
Resistance increases when smooth muscles of the medium and small size bronchioles constrict.
This causes decrease of the air flow.
Lung Compliance (the ease with which lungs can be expanded) also affects the air flow. It is
determined by two main factors:
o Distensibility of the lung tissue and surrounding thoracic cage
o Surface tension of the alveoli

Respiratory Volumes and Capacities
o Tidal volume (TV) – air that moves
into and out of the lungs with each
breath (approximately 500 ml)
o Inspiratory reserve volume (IRV) –
air that can be inspired forcibly
beyond the tidal volume (2100–
3200 ml)
o Expiratory reserve volume (ERV)
– air that can be evacuated from
the lungs after a tidal expiration
(1000–1200 ml)
o Residual volume (RV) – air left in
the lungs after strenuous expiration
(1200 ml)
o Inspiratory capacity (IC) – total
amount of air that can be inspired
after a tidal expiration (IRV + TV)
o Functional residual capacity (FRC)
– amount of air remaining in the lungs after a tidal expiration (RV + ERV)
o Vital capacity (VC) – the total amount of exchangeable air (TV + IRV + ERV)
o Total lung capacity (TLC) – sum of all lung volumes (approximately 6000 ml in males)

Front 21

Define dead spaces: anatomical, alveolar and total dead spaces.

Back 21

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Front 22

Define external respiration and internal respiration

Back 22

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Front 23

Describe partial pressure gradients.

Back 23

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Front 24

Define ventilation and perfusion and describe the mechanisms underlying ventilation-perfusion coupling

Back 24

Ventilation-perfusion coupling
Ventilation is the amount of gas reaching the alveoli. Perfusion is the blood flow reaching the alveoli. Ventilation and perfusion must be tightly regulated for efficient gas exchange
o Arterioles respond to changes of PO2
o Bronchioles respond to changes of PCO2
In the areas of high air flow, high PO2 causes arterial vasodilation, and therefore higher gas exchange. When the flow through the bronchiole is high in comparison with the
blood flow, low PCO2 causes bronchial constriction, decrease in air flow.
Internal Respiration:
The factors promoting gas exchange between systemic capillaries and tissue cells are the same as those acting in the lungs:
o Thickness and surface area varies in different organs. It may be changed by
constriction or dilation of precapillary sphincters.
o Gradient of partial pressures. The partial pressures and diffusion gradients are reversed: PO2 in tissue is always lower than in systemic arterial blood. And oxygen
diffuses out of the capillary. PCO2 in tissue is higher than in systemic blood. Carbon
dioxide diffuses into of the capillary.
o Perfusion rate is also dependant on metabolic activity of the organ. Increased
metabolic activity is associated with glucose degradation and CO2 production. CO2
and other metabolic products acts as local vasodilators increasing blood flow through
the organ

Front 25

List two respiratory centers in the brainstem and describe how they control respiration

Back 25

Respiratory Centers
o Medullary Respiratory Centers
 The dorsal respiratory group (DRG), or inspiratory center is located in the medulla. It
acts as the pacemaker as it capable of automaticity and rhythmicity. It sets normal
breathing rate of about 12-15 breaths/min. Stimuli generated here are conveyed down phrenic and intercostal nerves to the muscles of inspiration causing diaphragm and
external intercostal muscles to contract. DRG becomes dormant during expiration,
muscles relax, and we exhale.
 The ventral respiratory group (VRG) is involved in forced inspiration and expiration
o Pontine respiratory center
 Pontine, or = pneumotaxic respiratory group inhibits activity of inspiratory center and fine-tunes the breathing rate.

Front 26

Describe how Pco2, Po2, and arterial pH influence depth and rate of breathing

Back 26

Inspiratory depth is determined by how actively the respiratory center stimulates the respiratory muscles. Rate of respiration is determined by how long the inspiratory center is active
 Hypoventilation is slow and shallow breathing
 Hyperventilation is an increased depth and rate of breathing
 Apnea (breathing cessation) temporal cessation of breathing
Rate and depth of respiration can be affected by the following factors:
o PCO2
Increased levels of carbon dioxide in the blood diffuse into the CSF where it is hydrated;
resulting carbonic acid dissociates, releasing hydrogen ions.
o CO2 + H2O  H2CO3  H+
+ HCO3
-
High H+
levels are monitored by chemoreceptors of the brain stem. Thus, high PCO2 levels in the blood (hypercapnia) result in increased depth and rate of breathing (hyperventilation)
o Arterial pH
Changes in arterial pH can modify respiratory rate even if carbon dioxide and oxygen levels are normal. Increased ventilation in response to falling pH is mediated by peripheral
chemoreceptors.
o PO2
Partial pressure of oxygen in the blood is surprisingly less important in regulation of
respiration than PCO2. Chemoreceptors to PO2 of blood are found in carotid bodies and in aortic arch. Low PO2 causes hyperventilation.
o Exercise
Heavy exercise greatly increases respiratory rate. Mechanism is not well understood:
exercise-enhanced breathing is not prompted by an increase in PCO2 or a decrease in PO2 or pH
o Additional reflexes
 Stretch receptors in lungs cause inhibition of inspiration center (inflation reflex)
 Inhalation of gaseous irritants causes bronchospasm, cough and inhibition of inspiratory
center

Front 27

Explore the causes of hyperventilation and hypoventilation

Back 27

Inspiratory depth is determined by how actively the respiratory center stimulates the respiratory muscles. Rate of respiration is determined by how long the inspiratory center is active
 Hypoventilation is slow and shallow breathing
 Hyperventilation is an increased depth and rate of breathing
 Apnea (breathing cessation) temporal cessation of breathing
Rate and depth of respiration can be affected by the following factors:
o PCO2
Increased levels of carbon dioxide in the blood diffuse into the CSF where it is hydrated;
resulting carbonic acid dissociates, releasing hydrogen ions.
o CO2 + H2O  H2CO3  H+
+ HCO3
-
High H+
levels are monitored by chemoreceptors of the brain stem. Thus, high PCO2 levels in the blood (hypercapnia) result in increased depth and rate of breathing (hyperventilation)
o Arterial pH
Changes in arterial pH can modify respiratory rate even if carbon dioxide and oxygen levels are normal. Increased ventilation in response to falling pH is mediated by peripheral
chemoreceptors.
o PO2
Partial pressure of oxygen in the blood is surprisingly less important in regulation of
respiration than PCO2. Chemoreceptors to PO2 of blood are found in carotid bodies and in aortic arch. Low PO2 causes hyperventilation.
o Exercise
Heavy exercise greatly increases respiratory rate. Mechanism is not well understood:
exercise-enhanced breathing is not prompted by an increase in PCO2 or a decrease in PO2 or pH
o Additional reflexes
 Stretch receptors in lungs cause inhibition of inspiration center (inflation reflex)
 Inhalation of gaseous irritants causes bronchospasm, cough and inhibition of inspiratory center

Front 28

Describe inflation reflex (Hering-Breuer) reflex

Back 28

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Front 29

Describe how hypothalamus and cortex regulate breathing

Back 29

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