Functions of the RS
Ventilation, External respiration, Transport, Internal respiration
1.Ventilation
Movement of air into and out of lungs
2. External respiration
Gas exchange between air in lungs and blood
3. Transport
of oxygen and carbon dioxide in the blood
4.Internal respiration
Gas exchange between the blood and tissues
RS FUNCTIONS
Regulation of blood pH, Production of chemical mediators, Voice production, Olfaction, Protection
1. Regulation of blood pH
Altered by changing blood carbon dioxide levels
2. Production of chemical mediators
ACE; Hormones that work in the blood vessels. The lungs produce an enzyme called angiotensin-converting (ACE). Important for blood pressure regulation
3. Voice production
Movement of air past vocal folds makes sound and speech
4. Olfaction,
Smell occurs when airborne molecules are drawn into nasal cavity
5. Protection
Against microorganisms by preventing entry and removing them from respiratory surfaces.
Anatomy and Histology of the Respiratory System
Divided by Upper Tract and Lower Tract
Upper Tract
Nose, pharnyx, and associated structures
Lower Tract
Larynx, trachea, bronchi, lungs, and the tubing within the lungs
Nasal Cavity
From nares to choane, Vestibule, Hard Palate, Nasal Septum, Choanae, meastuses
Nares
(Nostrils) external openings of nasal cavity
Choanae
bony ridges on lateral walls with meatuses between. Openings to paranasal sinuses and to nasolacrimal duct
Vestibule
(entry room) just inside nares
Hard Palate
floor of nasal cavity
Nasal Septum
partition dividing cavity. Anterior cartilage; posterior vomer and perpendicular plate of ethmoid
Meatuses
Passageway beneath choanae
Functions of Nasal Cavity
-Passageway for air
-Cleans the air
-Humidifies, warms air
-Smell
-Along with paranasal sinuses are resonating chambers for speech
Pharynx
3 regions: Nasopharynx, Oropharynx. Laryngopharynx
Nasopharynx
pseudostratified columnar epithelium with goblet cells. Mucous and debris is swallowed. Openings of Eustachian (auditory) tubes. Floor is soft palate, uvula is posterior extension of the soft palate.
Oropharnyx
shared with digestive system. Lined with moist stratified squamous epithelium
Laryngopharynx
epiglottis to esophagus. Lined with moist stratified squamous epithelium
Larynx
located in the anterior part of the throat and extends from the base of the tongue to the trachea. Passageway for air between the pharynx and the trachea. Has paired and unpaired cartilages.
Unpaired Cartilages
Thyroid, Cricoid, Epiglottis
Thyroid
Largest; Adam's apple
Cricoid
most inferior, base of larynx
Epiglottis
attached to thyroid and has a flap near base of tongue. Elastic rather than hyaline cartilage
Paired Cartilages
Arytenoids, Corniculate, Cuneiform
Arytenoids
attached to cricoid
Corniculate
attached to arytenoids
Cuneiform
contained in mucous membrane
Vestibular folds / False Vocal folds
Mucous membrane that cover the superior ligaments
True vocal cords / Vocal folds
sound production. Opening between is glottis
Functions of Larynx
-Maintain an open passageway for air movement: thyroid and cricoid cartilages
-Epiglottis and vestibular folds prevent swallowed material from moving into larynx
-Vocal folds are primary source of sound production. Greater the amplitude of vibration, loud
Vocal Folds
Inferior ligaments are covered by a mucous membrane, (true vocal cords) The vocal folds and the opening between them is called GLOTTIS
Trachea
-Membranous tube of dense regular connective tissue and smooth muscle; supported by 15-20 hyaline cartilage C-shaped rings open posteriorly. Posterior surface is elastic ligamentous membrane and bundles of smooth muscle called the trachealis. Contracts du
Tracheobronchial Tree
-Trachea to terminal bronchioles which is ciliated for removal of debris.
>Trachea divides into two primary bronchi.
>Primary bronchi divide into secondary bronchi (one/lobe) which then divide into tertiary bronchi.
>Bronchopulmonary segments: defined by
Respiratory zone
site for gas exchange
Respiratory bronchioles
-branch from terminal bronchioles. Respiratory bronchioles have very few alveoli. Give rise to alveolar ducts which have more alveoli. Alveolar ducts end as alveolar sacs that have 2 or 3 alveoli at their terminus.
-No cilia, but debris removed by macroph
The Respiratory Membrane
-Three types of cells in membrane; Type I pneumocytes, Type II pneumocytes, Dust Cells
-Layers of the respiratory membrane
>Thin layer of fluid lining the alveolus
>Alveolar epithelium (simple squamous epithelium
>Basement membrane of the alveolar epithel
Type I pneumocytes
Thin squamous epithelial cells, form 90% of surface of alveolus. Gas exchange
Type II pneumocytes
Round to cube-shaped secretory cells. Produce surfactant (lipids+proteins, stabilize the alveoli)
Dust cells
phagocytes
Lungs
Two lungs: Principal organs of respiration
-Right lung: three lobes. Lobes separated by fissures
-Left lung: Two lobes, and an indentation called the cardiac notch
Base, apex, hilus
Base
sits on diaphragm
apex
apex at the top
hilus
on medial surface where bronchi and blood vessels enter the lung. All the structures in hilus called root of the lung.
Divisions of lungs
Divided into lobes, bronchopulmonary segments, and lobules
Lobes
(supplied by secondary bronchi
bronchopulmonary segments
supplied by tertiary bronchi and separated from one another by connective tissue partitions
Lobules
supplied by bronchioles and separated by incomplete partitions
Inspiration
diaphragm, external intercostals, pectoralis minor, scalenes
-Diaphragm: dome-shaped with base of dome attached to inner circumference of inferior thoracic cage. Central tendon: top of dome
>Quiet inspiration: accounts for 2/3 of increase in size of thora
Expiration
muscles that depress the ribs and sternum: abdominal muscles and internal intercostals
-Quiet expiration: relaxation of diaphragm and external intercostals with contraction of abdominal muscles
-Labored breathing: all inspiratory muscles are active and co
Pleura
Pleural cavity, Visceral pleura, Parietal pleura, Pleural fluid, Mediastinum
Pleural cavity
surrounds each lung and is formed by the pleural membranes. Filled with pleural fluid
Pleural fluid
acts as a lubricant and helps hold the two membranes close together (adhesion).
Visceral pleura
adherent to lung. Simple squamous epithelium, serous
Mediastinum
central region, contains contents of thoracic cavity except for lungs
Blood and Lymphatic Supply
-Two sources of blood to lungs:
>Pulmonary artery brings deoxygenated blood to lungs from right side of heart to be oxygenated in capillary beds that surround the alveoli. Blood leaves via the pulmonary veins and returns to the left side of the heart.
>Ox
Ventilation
-Movement of air into and out of lungs
-Air moves from area of higher pressure to area of lower pressure
-
Boyle's Law
: P = k/V, where P = gas pressure, V = volume, k = constant at a given temperature
-If barometric pressure is greater than alveolar pres
Changing Alveolar Volume
Lung recoil causes alveoli to collapse resulting from
Elastic recoil, Surface tension
Elastic recoil
elastic fibers in the alveolar walls
Surface tension
film of fluid lines the alveoli. Where water interfaces with air, polar water molecules have great attraction for each other with a net pull in toward other water molecules. Tends to make alveoli collapse
Surfactant
Reduces tendency of lungs to collapse by reducing surface tension. Produced by type II pneumocytes.
Respiratory distress syndrome (hyaline membrane disease).
Common in infants with gestation age of less than 7 months. Not enough surfactant produced.
Pleural Pressure
#NAME?
Measurement of Lung Function
Spirometry, Tidal volume, Inspiratory reserve volume, Expiratory reserve volume, Residual volume
Spirometry
measures volumes of air that move into and out of respiratory system. Uses a spirometer
Tidal volume
amount of air inspired or expired with each breath. At rest: 500 mL
Inspiratory reserve volume
amount that can be inspired forcefully after inspiration of the tidal volume (3000 mL at rest)
Expiratory reserve volume
amount that can be forcefully expired after expiration of the tidal volume (100 mL at rest)
Residual volume
volume still remaining in respiratory passages and lungs after most forceful expiration (1200 mL)
Pulmonary Capacities
The sum of two or more pulmonary volumes
Inspiratory capacity, Functional residual capacity, Vital capacity, Total lung capacity
Inspiratory capacity
tidal volume + inspiratory reserve volume
Functional residual capacity
expiratory reserve volume + residual volume
Vital capacity
sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume
Total lung capacity
sum of inspiratory and expiratory reserve volumes + tidal volume and residual volume.
Minute ventilation
total air moved into and out of respiratory system each minute; tidal volume X respiratory rate
Respiratory rate (respiratory frequency):
number of breaths taken per minute
Anatomic dead space
formed by nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles
Physiological dead space
anatomic dead space + the volume of any alveoli in which gas exchange is less than normal.
Alveolar ventilation (VA)
volume of air available for gas exchange/minute
Dalton's law
total pressure is the sum of the individual pressures of each gas
Henry's Law
Concentration of a gas in a liquid is determined by its partial pressure and its solubility coefficient
Diffusion of gases / Gas Exchange, 4 Factors
1. Membrane thickness
2. Diffusion coefficient of gas
3. Surface Area
4. Partial Pressure Differences
1. Membrane Thickness
The thicker, the lower the diffusion rate
2. Diffusion coefficient of gas
(measure of how easily a gas diffuses through a liquid or tissue). CO2 is 20 times more diffusible than O2, surface areas of membrane, partial pressure of gases in alveoli and blood
3. Surface Area
Diseases like emphysema and lung cancer reduce available surface area
4. Partial pressure differences
Gas moves from area of higher partial pressure to area of lower partial pressure. Normally, partial pressure of oxygen is higher in alveoli than in blood. Opposite is usually true for carbon dioxide
Oxygen
-Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary
-PO2 in blood decreases because of mixing with deoxygenated blood
-Oxygen moves from tissue capillaries into the tissues
Carbon Dioxide
-Moves from tissues into tissue capillaries
-Moves from pulmonary capillaries into the alveoli
Hemoglobin and Oxygen Transport
-Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%)
-Oxygen-hemoglobin dissociation curve: describes the percentage of hemoglobin saturated with oxygen at any given PO2
-Oxygen-hemoglobin dissociation curve at rest shows that he
Bohr Effect
-Effect of pH on oxygen-hemoglobin dissociation curve: as pH of blood declines, amount of oxygen bound to hemoglobin at any given PO2 also declines
-Occurs because decreased pH yields increase in H+ that combines with hemoglobin changing its shape and oxy
Effects of CO2 and Temperature
-Increase in PCO2 causes decrease in pH
-Carbonic anhydrase causes CO2 and water to combine reversibly and form H2CO3 which ionizes to H+ and HCO3-
-Increase temperature: decreases tendency for oxygen to remain bound to hemoglobin, so as metabolism goes u
Effect of BPG
2,3-bisphosphoglycerate (BPG)
: released by RBCs as they break down glucose for energy
-Binds to hemoglobin and increases release of oxygen
Fetal Hemoglobin
-Fetal hemoglobin picks up oxygen from maternal hemoglobin for several reasons
-Concentration of fetal hemoglobin is 50% greater than concentration of maternal hemoglobin.
-Oxygen-hemoglobin dissociation of fetal hemoglobin is left of maternal; i.e., feta
Transport of Carbon Dioxide
-Carbon dioxide is transported as bicarbonate ions (70%) in combination with blood proteins (23%: primarily hemoglobin) and in solution with plasma (7%)
-Hemoglobin that has released oxygen binds more readily to carbon dioxide than hemoglobin that has oxy
Carbon Dioxide Transport
(a)
Tissue capillaries: as CO2 enters red blood cells, reacts with water to form bicarbonate and hydrogen ions. Chloride ions enter the RBC and bicarbonate ions leave:
chloride shift
. Hydrogen ions combine with hemoglobin. Lowering the concentration of b
Regulation of Ventilation
Medullary respiratory center, Pontine (pneumotaxic) respiratory group
Medullary respiratory center,
-Dorsal groups stimulate the diaphragm
-Ventral groups stimulate the intercostal and abdominal muscles
Pontine (pneumotaxic) respiratory group
-Involved with switching between inspiration and expiration
-Dorsal group controls the diaphragm
-When diaphragm is contracted you breathe IN
Intercostal = expiration
External intercostal = inspiration
Pontine = switching
Phrenic Nerve = diaphragm
Rhythmic Ventilation
1. Starting inspiration
2. Increasing inspiration
3. Stopping inspiration
1. Starting inspiration
-Medullary respiratory center neurons are continuously active
-Center receives stimulation from receptors and simulation from parts of brain concerned with voluntary respiratory movements and emotion
-Combined input from all sources causes action potentia
2. Increasing inspiration
More and more neurons are activated
3. Stopping inspiration
-Neurons stimulating also responsible for stopping inspiration and receive input from pontine group and stretch receptors in lungs. Inhibitory neurons activated and relaxation of respiratory muscles results in expiration.
Apnea
Cessation of breathing. Can be conscious decision, but eventually PCO2 levels increase to point that respiratory center overrides
Apnea = happens when you're diving into water
If you've done apnea for a long time -> hyperventilation
Could faint
Hyperventilation
-Causes decrease in blood PCO2 level. Peripheral vasodilation causes decrease in BP. Fainting. Problem before diving.
-Cerebral and limbic system. Respiration can be voluntarily controlled and modified by emotions
Hypercapnia
Too much CO2
Hypocapnia
Not enough CO2
Hering-Breuer Reflex
Limits the degree of inspiration and prevents overinflation of the lungs
-Infants
>Reflex plays a role in regulating basic rhythm of breathing and preventing overinflation of lungs
-Adults
>Reflex important only when tidal volume large as in exercise
Effect of Exercise on Ventilation
Ventilation increases abruptly
-At onset of exercise
-Movement of limbs has strong influence
-Learned component
Ventilation increases gradually
-After immediate increase, gradual increase occurs (4-6 minutes)
-Anaerobic threshold: highest level of exercis
Effects of Aging
-Vital capacity and maximum minute ventilation decrease
-Residual volume and dead space increase
-Ability to remove mucus from respiratory passageways decreases
-Gas exchange across respiratory membrane is reduced