Chapter 23 Flashcards
Respiration
Is gas exchange: O2 and CO2
Occurs between atmosphere and body cells. Cells need O2 for aerobic ATP production and need to dispose of CO2 that process produces
respiratory system
provides the means for gas exchange
Consists of respiratory passageways in head, neck, and trunk, and the lungs
General function of Respiratory system
1 Site for exchange of oxygen and carbon dioxide
(O2 diffuses from alveoli to blood)
(C02 diffuses from blood to alveoli)
2. Air passageway between atmosphere and lungs
3. Detection of odors (olfactory receptors)
4. Sound production (vocal cords of the larnynx vibrate as air move over them
Upper Respiratory tract
Nose, nasal cavity, pharynx, Larynx
Lower Respiratory tract
Trachea, Bronchus, Bronchiole, terminal bronchiole
Respiratory zone
Respiratory Bronchiole, Laveolar duct, Alveoli
What is Respiratory Mucosa composed of
Epithelium resting on a basement membrane and an underlying lamina proprietary composed of areolar connective tissue
Respiratory Mucosa layers
-Muscous (Mucin and H2O)
-Cilia (sweep muscus and microorganisms)
-Epithelium
-Basement membrane
-Lamina propria (mucous and serous glands, watery secretion)
Pseudostratified ciliated columnar epithelium
-Lines the nasal cavity, paranasal sinuses, nasopharynx, trachea, inferior portion of larynx, main bronchi and lobar bronchi
Simple Ciliated Columnar Epithelial
Lines the segmental bronchi, smaller bronchi, and large Bronchioles
Simple cuboidal epithelium
Lines the terminal respiratory bronchioles
Simple squamous epithelium
Forms both the alveolar dots and alveoli
Parts of the throat
Nasopharynx, oropharynx, larynopharnyx
External nose
Nasal bone, septal nasal cartilage, lateral cartilage, dense irregular connective tissue, nostrils (nares)
Nasal Cabot
from nostrils (nares) to choanae
Choanae
paired posterior nasal apertures (openings) that lead to pharynx
what does the nasal cavity do
Warms: extensive blood vessels
Cleans: mucus & cilia
Humidifies: secretions of nasal cavity
Turbulence by conchae enhances all three processes
Nasal vestibule
Skin & vibrissae (coarse hairs)
(coarse particles)
Olfactory region
Olfactory epithelium odor detection
Respiratory
Many blood vessels
Pseudostratified ciliated columnar epithelium
Seromucous glands in lamina propria
Conchae (turbinate bones)
Paired bones on lateral walls that project into nasal cavity
Divides cavity into passages called meatuses
Each is immediately inferior to its concha
Paranasal sinuses:
spaces within skull bones
Pseudostratified ciliated columnar epithelium
Mucus swept into pharynx and swallowed
Ducts connect to nasal cavity
Condition the air
Provide resonance to voice
Lighten the skull
4 kinds of sinus
Frontal sinus, ethmoidal sinus, sphenoidal sinus, maxillary sinus
Pharynx:
funnel-shaped passageway posterior to nasal cavity
Connects nasal cavity & mouth to larynx and esophagus
Wall with skeletal muscle throughout
13 c, long
Nasopharnyx
Most superior pharyngeal region; air only; pseudostratified ciliated columnar
Soft palate & uvula elevate when swallowing
Connected to middle ear via auditory (Eustachian) tubes
oropharynx
Middle pharyngeal region; food & air; nonkeratinized stratified squamous
Palatine tonsils on lateral walls
Lingual tonsil on posterior tongue surface
Laryngopharynx
Inferior, narrow pharyngeal region; food & air; nonkeratinized stratified squamous
Where respiratory & digestive systems diverge
Continuous with esophagus posteriorly
Food has right-of-way
Cartilages of the Larynx
9 cartilages held in place by ligaments, muscles, membranes
Larynx (voice box)
Cylindrical airway between laryngopharynx & trachea
Air passageway
Switching mechanism to route air & food into the proper channels
Voice production
-Attached to hypoid bone superiorly
Kinds of Cartilage in larynx
3 external unpaired: thyroid, cricoid, epiglottis
3 internal paired: arytenoid, corniculate, cuneiform
All but epiglottis are hyaline cartilage
Thyroid cartilage
largest, shield-shaped, has anterior protrusion called laryngeal prominence
(Adams apple)
Cricoid cartilage
: inferior to thyroid, ring-shaped, anchored to trachea inferiorly
Arytenoid, corniculate, & cuneiform cartilages
form part of lateral and posterior walls of larynx
Epiglottis:
anchored to thyroid cartilage, leaf- or spoon-shaped
Projects posterosuperiorly into the pharynx
Closes over laryngeal inlet during swallowing
(Guardian of the airway)
vocal fold of the Larynx
(elastic fibers) under laryngeal mucosa on both sides
-Attach arytenoid to thyroid cartilage and forms vocal floss
Vocal Folds and Voice Production
Vocal folds vibrate to produce sound as air rushes up from the lungs
Airflow
amount of air moving in and out of lungs with each breath
Glottis
vocal fols and opening
Pulmonary Ventilation
process of air moving in and out
components of Pulmonary Ventilation
Airflow, Pressure Gradients, and Resistance
Pressure gradient
established between Patm & Ppul
Airflow =
pressure gradient divided by resistance
Difference between Patm & Ppul
-can be changed by altering volume of thoracic cavity
-Deeper breather higher thoracic volume = lower Ppul = higher pressure gradient
Factors that influence airflow resistance
- Bronchiole diameter (side of air passageway)(Higher resistance less air)
- Compliance =ease of expansion of chest cavity (elasticity of chest wall and surface tension)
elasticity effects on airflow
lower elasticity, high resistance, low airflow
Surface tension effect on airway
Higher surface tension, higher resistance, less airflow
tidal volume
the amount of air that moves in or out of the lungs with each respiratory cycle.
Inspiratory reserve volume
the amount of air taken into lungs during a forced inspiration, following a quiet inspiration, IRV is measure of lung compliance
Expiratrory reserve volume
The amount of air expelled from. lungs during a forced expiration following a quiet expiration, ERV is a measure of lung and chest wall elasticity
Residual volume
the amount of air left in the lungs following an expiration
Obstructive diseases
increased airway resistance and may show increased TLC, FRC, and RV
Restructive disease
decreased compliance and may show less TLC FRC RV and VC
Impiratory capacity
TV + IRV total ability to inspire
(3600, 2400)
Functional residual capacity
ERV + IRV
Amount of air normally left residual in lungs after you expire quietly
(2400, 2800)
Vital capacity
TV+IRV+ERV max amount of air that can be forcefully expired after a forced inspiration
(4800, 3100)
Total Lung capacity
TV + IRV + ERV + RV
Max amount of air that can be held
(6000, 4200)
Forced vital capacity (FVC)
Volume of air expired when subject takes a deep breath and forcefully exhales as maximally and quickly as possible
Forced expiratory volume
Percent of vital capacity that can be expelled in one second
Obstruction (more then 80%) difficult to expire
Restrictive (less then 80%) difficult to inspire
75-85%
Anatomical dead space (Vd)
(150 mL) volume of air left in conducting zone after inspiration 12-20 breaths/min
TV = tidal volume (500 mL)
Minute Ventilation (Ve)
Volume of air moved in & out of lungs per minute
f x TV = 12 breaths/min x 500 mL/breath = 6000 mL/min
= 6 L /min
Alveolar Ventilation (VA)
Volume of air reaching the alveoli per minute
f x (TV - VD) = 12 breaths/min x (500 – 150 mL/breath)
= 12 breaths/min x 350 mL/min = 4200 mL/m = 4.2 L /min v
Gas exchange between atmosphere & cells to meet metabolic demands Steps
Gas exchange between atmosphere & cells to meet metabolic demands
1. air containing O2
2. O2 moves into blood
3. Blood contains O2
4. O2 moves into systemic cells
5. CO2 moves into blood
6. Blood containing CO2
7. CO2 moves into alveoli
8. Air containing CO2
Respiration: 4 Continuous Processes
Pulmonary ventilation, pulmonary gas exchange, gas transport, tissue gas exchange
Dalton’s Law of Partial Pressures
The total pressure in a mixture of gases is equal to the sum of the pressures exerted independently by each gas (i.e., its partial pressure) in the mixture
Partical pressure = total pressure of x% of the gas in the mixture = P”gas” (PO2 Pco2)
Gases contained in air
N2, O2, CO2, H2O
Patm
= 760 mm Hg at sea level = PN2 + PO2 + PCO2 + PH2O
Partial pressure =
total pressure of mixture x % of that gas in the mixture (e.g., N2 = 760 mm Hg x 0.786 (78.6%) = 597 mm Hg)
How does PCO2 control Ventilation
by changing bronchiole diameter
How does PO2 control perfusion
by arteriole diameter
Ventilation less than perfusion
Mismatch:causes local increase of PCO2 and decrease of PO2
-pulmonaey arterioles serving these alveoli constrict bronchioles will dilate in response to increased CO2
Match: Decreased ventilation and decreased perfusion
Ventilation greater than perfusion
Increased ventilation and perfusion of alveoli causes local decrease of PCO2 and increased PO2
Pulmonary arterioles serving these alveoli dilate
Match: increased ventilation and perfusion
Blood’s ability to transport O2 depends on
- Solubility coefficient of O2 low only 2% O2 in plasma
- Amount of available hemoglobin (Hb) About 98% of O2 is bound to HbHbO2 = oxyhemoglobin; HHb is deoxyhemoglobin
Three Ways to Transport Carbon Dioxide in Blood
As CO2 dissolved in plasma (7%)
Chemically bound to globin of Hb (23%)
CO2 + Hb HbCO2 (carbaminohemoglobin)
As bicarbonate ions (HCO3-) in plasma (70%)
CO2 + H2O H2CO3 HCO3- + H+
Occurs inside RBC as they have the enzyme
H+ binds to Hb & buffers pH
Conversion of Carbon Dioxide to Bicarbonate
- CO2 movement CO2 diffuses into erythrocyte
- Formation of HCO3 and H+ once the erthycyte CO2 is joined to H2O to form carbonic acid by carbonic anhydrase H2CP32 splits into biatcarbonite and hydrogen ion (C)2 + H20 H2CO3. HCO3 + H+
- Chloride movement HCo3 which is negatively charged exits from the erythrocyte
Conversion of HCO3 to CO2 at pulmonary capillaries
- Chloride movement HCO3 moves into the erythrocyte as CL- moves out
- Formation of CO2 and H2O HCO3 recombines with H+ to form H2CO3 which dissocitates into CO2 and H2O
- CO2 movement CO2 diffuses our of the erythrocytes into the plasma CO2 diffuses into an alveolus
Hemoglobin (Hb) transports
O2 attached to iron
CO2 bound to globin
H+ ions bound to globin
Binding of one substance causes a change in shape of Hb
Influences the ability of Hb to bind or release the other two substances
How many molecules can each Hb binds to
4 O2 Molecules (O2 sats)
Oxygen-Hemoglobin Saturation Curve
Relates % O2 saturation of Hb to PO2
Large changes initially with small increases in PO2
O2 loading at lungs (pulmonary capillaries) & unloading at tissues (systemic capillaries)
What happens to PO2 when altitude goes up
PO2 goes down
PO2 in blood after leaving lungs
104 mmHg = O2 sat =98%
PO2 in blood after tissue gas exchange at rest
40 mmHg (75%)
Oxygen Reserve
O2 that remains bound to Hb after passing through systemic circulation
PO2 in blood leaving lungs = 104 + 98% sat
PO2 in blood after tissue gas exchange during exercise = 20mmHg =35% O2
63% of transported O2 was released during tissue gas exchange
Variables That Influence Hb’s Binding & Release of O2
- PO2 in blood most important
- Temp
- Blood pH (H+ binds Hb) lower pH and higher H+)
- Blood PCO2 (binds to Hb)
- Amount of 2,3-bisphosphoglycerate (BPG) in the blood
RBCs produce BPG as they use glucose
Temperatures influence on hemoglobin saturation
More oxygen is released as temp increases
pH influences on hemoglobin saturation
More oxygen is released as pH decrease
Respiratory center
Autonomic nuclei of brainstem that coordinate breathing
Medulla & pons
Ventral respiratory group (VRG)
-Inspiratory neurons excite phrenic and intercostal nerves causing contraction of diaphragm and external intercostals
-Expiratory neruuons stop incporatory firing muscles relax and lungs recoil
Dorsal respiratory group (DRG)
-Inspiratory neurones only
Receives and integrates sensory inputs and relays them to VRG
Pontine respiratory center (PRC)
Regulates DRG & VRG
Receives sensory inputs like DRG
Ensures smooth transaction between inspiration & expiration
Damage to this area results in long, gasping inspirations followed by occasional expirations called
Chemoreceptors
Most important stimulus is blood PCO2
increased stimuli, increased breathing rate and depth increased ventilation = more exhaled = homeostasis
Central chemo receptors
-in medulla, monitor pH of CSF
-Changes in H+ induced by changes in blood PCO2
-Increased blood PCO2 = Diffusion into CSF = Increased conversion of CO2 to HCO3 + H+ = increased H+ = stimulation of chemoreccpetor s
Peripheral chemoreceptors
In aortic arch bifurcation of common carotid arteries
Respond to H+ from sources other than PCO2 conversion
increased blood PCO2, decreased pH, or large decreased in PO2 to around 60 mm Hg (PO2 is normally ~100 mm Hg when it reaches these chemoreceptors)
Small decreased blood PO2 increased chemoreceptor sensitivity to increased blood PCO2
Proprioceptors
in joints and muscles stimulated by movements increased breathing depth
Baroreceptor
In visceral pleura & bronchiole smooth muscle
Stimulated when overstretched
Initiate inhalation reflex (Hering-Breuer reflex) to shut off inspiration and protect againstoverinflation of lungs
Irritant receptors
in air passageways
stimulated by particulates
Causes forceful muscle contraction
Higher Brain Centers
Hypothalamus and limbic system alter breathing rate & depth in response to temperature, emotions & pain via medullary respiratory center
Central cortex controls voluntary changes in breathing by directly stimulating Lower motor neurons
Hyperventilation
breathing rate or depth above body’s demand
Higher Po2 Nd lower PCO2 in alveoli which increases pressure gradient between alveoli and blood = PCO2 decreases blood
Hypocarnia
lower blood CO2
Low blood CO2 causes
vasoconstriction
respiratory alkalosis
a pathology that is secondary to hyperventilation. Hyperventilation typically occurs in response to an insult such as hypoxia, metabolic acidosis, pain, anxiety, or increased metabolic demand.
Hypoventilation
breathing too slow bradypnea or too shallow hypopnea
PO2 decreased and PCO2 increased in alveoli which decreased pressure between alveoli and blood and increase PCo2
Low blood CO2 is
Hypercarnia
Low blood PO2
Hyposemia
Respiratory acidosis
a state in which there is usually a failure of ventilation and an accumulation of carbon dioxide.
Breathing and Exercise
-Hyperpnea to meet increased tissue needs during exercise
Depth increases rate remains the same
Blood PO2 and Blood PCO2 remain relatively constant
The respiratory center is stimulated due to:
Proprioceptor stimulation in response to movement
Motor output from cerebral cortex
Conscious anticipation of exercise
