Physiology of Respiratory System Flashcards
External respiration consists of (2):
- pulmonary ventilation/breathing
- gas exchange in pulmonary capillaries of the lungs
Internal respiration consists of:
- systemic tissue gas exchange
- cellular respiration
metabolic reactions that consume oxygen and give off CO2 during the production of ATP
cellular respiration
2 phases of pulmonary ventilation/breathing:
inspiration/inhalation: moves air into the lungs
expiration/exhalation: moves air out of the lungs
the rate of airflow and amount of effort needed for breathing are influenced by _________, ________, and ________.
- alveolar surface tension
- compliance of the lungs
- airway resistance
air flows from ____ pressure to _____ pressure.
high pressure to low pressure
alveolar pressure (PA) < atmospheric pressure (PB) =
inspiration
alveolar pressure (PA) > atmospheric pressure (PB) = expiration
expiration
pressure gradients are established by changes in the size of the thoracic cavity, produced by ____ and ______ of respiratory muscles
contraction and relaxation
Law: the pressure of a gas in a closed container is inversely proportional to the volume of the container
Boyle’s Law
_____ is important for understanding the pressure changes that occur in the lungs and thorax during the breathing cycle
Boyle’s Law
______:
expansion of the thorax –> decreased alveolar pressure –> air flows in to lungs
inspiration
most important muscle of respiration is the ______. Contraction of this muscle causes it to flatten and increase the vertical diameter of the thoracic cavity
diaphragm
the 2nd most important muscle of respiration are the ______ . When they contract, the ribs elevate increasing the anteroposterior and lateral diameters of the chest cavity
external intercostals
contraction of the ______ is responsible for about 25% of the air that enters the lungs during normal respiration
intercostals
expansion of the thorax results in _______ alveolar pressure.
decreased
Air moves into the lungs when alveolar pressure…
drops below atmospheric pressure
a passive process that begins when inspiratory muscles are relaxed, decreasing the size of the thorax
There is no active muscle movement
quiet expiration
at max inspiration, the atmospheric pressure and alveolar pressure are ____, meaning no more movement of air
equal
decreasing thoracic volume ____ alveolar pressure above atmospheric pressure –> air moves out of the lungs
increases
tendency of pulmonary tissues to return to a smaller size after having been stretched during inspiration
elastic recoil
how much effort is required to stretch the lungs and chest wall
compliance
lungs and chest wall expand easily
high compliance
lungs and chest wall resist expansion
low compliance
the 2 principle influences on compliance:
elasticity
surface tension
Surfactant reduces the pressure difference needed to allow the lung to inflate. The lung’s compliance decreases and ventilation decreases when lung tissue becomes _______ and _____.
diseased and fibrotic
Airway resistance:
Normal inspiration:
- bronchioles __#1___ because their walls are pulled outward in all directions
- __#2____ resistance
Normal exhalation:
- brochioles return to resting diameter with __#3___ of lungs
- ___#4___ resistance
- enlarge
- decreased resistance
- elastic recoil
- increased resistance
any condition that narrows or obstructs airways _____ resistance. i.e. asthma, emphysema, chronic bronchitis, COPD
increases
Respiratory muscles for inspiration (7)
- diaphragm
- external intercostals
mm that aid in forced inspiration:
- scalenes
- SCM
- Trapezius
- Pectoralis Major
- Pectoralis Minor
Respiratory muscles for forced exhalation (5)
- internal intercostals
- rectus abdominus
- external oblique
- internal oblique
- transverse abdominus
the amounts of air moved in and out of the lungs and remaining in them
pulmonary volumes
instrument used to measure volume of air exchanged in breathing
spirometer
amount of air inhaled and exhaled in normal breathing
tidal volume (TV)
when you take a deep breath, more than 500mL of air is inhaled. This additional air is the _________.
inspiratory reserve volume (IRV)
Tidal volume = the volume of one breath averages about ____mL of air into and out of the lungs
500mL
IRV is approximately ____mL in an adult male and ___mL in an adult female
- 3100
- 1900
amount of air that can be exhaled after normal exhalation
expiratory reserve volume (ERV)
average ERV is approx. ____ mL in men and ___mL in women
- 1200
- 700
amount of air that cannot be forcibly exhaled
residual volume (RV)
measuring _______ helps monitor the response of treatment and progression of respiratory disease
lung capacity
represents the largest volume of air an individual can move in and out of the lungs
vital capacity (VC)
VC = TV + IRV + ERV
maximal amount of air an individual can inspire after a normal expiration
Inspiration Capacity (IC)
IC = TV + IRV
the amount of air in lungs at the end of normal expiration (no contraction of expiratory muscles)
functional residual capacity
(FRC)
FRC = ERV + RV
total volume of air a lung can hold
total lung capacity (TLC)
TLC = VC + RV
factors than affect lung volumes: (3)
- chest wall deformities (scoliosis, kyphosis)
- neuromuscular disorders (Lou Gehrig’s disease
- pleural disease (fluid in pleural space)
All of these are restrictive respiratory diseases
volume of air blown out in the 1st second of forced expiration
forced expiratory volume (FEV1)
vital capacity measured during forced expiration
Forced vital capacity (FVC)
a FEV/FVC of #% indicated that there isn’t likely any obstruction to air flow out of the lungs
80%
Diseases that affect the airways themselves, causing an airflow limitation or an airflow obstruction
obstructive lung diseases
ie.
- bronchitis: excessive mucus production
- ephysema: alveoli collapse
- COPD
- Astma
the volume of inspired air that reaches the alveoli
only this volume of air takes part in the exchange of gases between air and blood. Gas exchange only occurs in the alveoli
alveolar ventilation
air in passageways that do not participate in gas exchange
anatomical dead space
anatomical dead space plus the volume of any nonfunctioning alveoli (as in pulmonary disease)
physiological dead space
treatments to increase alveolar ventilation (3):
- diaphragmatic breathing
- mobilization = exercise
- aiding clearance of secretions (eg. CPT, postural drainage)
pressure exerted by one gas in a relative mixture of gases or in a liquid
partial pressure of gas
partial pressure of gas is directly related to the relative concentration of the gas in the mixture
gases will diffuse down their concentration gradient from an area of ____ concentration to ___ concentration
high to low
4 main factors that determine the amount of oxygen that diffuses into blood:
- oxygen pressure gradient between alveolar air and incoming pulmonary blood
- total functional surface area of the respiratory membrane
- respiratory minute volume
- alveolar ventilation
the oxygen pressure gradient between alveolar air and incoming pulmonary blood
pulmonary gas exchange
anything that lowers the alveolar PO2 will ____ the pressure gradient
decrease
anything that decreases the number of alveoli available for gas exchange will _____ the functional surface area
decrease
total volume of air inhaled and exhaled each minute
respiratory minute volume
anything that decreases respiratory rate or volume inspired per minute will ____ minute volume
decrease
decreased exchange of gases related to obstruction
preventing inspired air from getting to the alveoli
foreign body, secretions, disease
alveolar ventilation (decreased)
structural factors that facilitate oxygen diffusion from alveolar air to blood:
- walls of alveoli and capillaries form only thin barrier for gases to cross
- alveolar and capillary surfaces are large
- blood is distributed through the capillaries in a thin layer so each red blood cell comes in close contact to alveolar air
how blood transports gases:
- O2 and CO2 are transported as solutes and as parts of molecules of certain chemical compounds
- Immediately upon entering the blood, both O2 and CO2 dissolve in the plasma
- Most of the O2 and CO2 molecules form a chemical union with some other molecule such as hemoglobin
a reddish protein pigment found only inside red blood cells
made up of 4 polypeptide chains each with an iron-containing heme group
hemoglobin
A _____ is the binding agent for oxygen on the hemoglobin molecule
iron atom
As hemoglobin has 4 binding heme groups it can transport up to # atoms of oxygen
4
______ binds to amino acid chains on hemoglobin
carbon dioxide
oxygenated blood contains about # ml of dissolved oxygen per 100 ml of blood
0.3 ml
hemoglobin _____ the oxygen-carrying capacity of blood
increases
the exact amount of O2 in the blood depends mainly on the _____.
amount of hemoglobin present
to combine with hemoglobin, oxygen must diffuse from plasma into ______ where hemoglobin molecules are located
red blood cells
oxygen travels in 2 forms:
- as dissolved O2 in the plasma
- as O2 associated with hemoglobin (oxyhemoglobin)
an illustration of the rate at which hemoglobin combines with oxygen in lung capillaries
increasing blood PO2 accelerates hemoglobin association with oxygen (concentration gradient)
O2 Hb dissociation curve
______ carries the majority of the total oxygen transported by blood
oxyhemoglobin
a small hand-held device that measures the color of blood in a superficial capillary bed. The device gives an indirect reading of the oxygen saturation of the blood.
pulse oximeter
Carbon dioxide is carried in the blood similarly to oxygen:
- a small amount of CO2 is dissolved in plasma
- about 20% of CO2 combines with NH2 (amine) groups of hemoglobin = carbamino compounds (carbaminohemoglobin)
most CO2 (about 60%) is carried in plasma as ______.
bicarbonate ions
an increase of carbon dioxide in the blood causes an increase in ____, or a drop in pH in the blood
acidity
exchange of gases in tissues takes place between ____ and _____. This occurs because of pressure gradients for both oxygen and carbon dioxide
- blood flowing through capillaries
- tissue cells
oxygen diffuses out of ______ into cells and carbon dioxide diffuses from cells into venous blood.
arterial blood
homeostasis of blood gases is maintained primarily by means of changes in ventilation:
rate and depth of breathing
the main integrators of homeostasis of gases in the blood are located within the ____, _____, and _____
- brainstem
- carotid bodies
- aorta
several mechanisms help match breathing effort to metabolic demand
respiratory center is divided into 2 parts:
- medullary respiratory center
- pontine respiratory group
basic breathing rhythm can be altered by different inputs to the ____ and ____.
medulla and pons
input from the ____ helps to regulate breathing rhythm (inspiration and expiration)
pons
input from the ____ can override subconcious control of breathing - intentional deep breath
cerebral cortex
input from _____ within the medulla are sensitive to PCO2 and pH
chemoreceptors
feedback information to the medulla is also brought in from other control centers:
- peripheral chemoreceptors
- carotid bodies and aorta
an increase in PCO2 = __#1__
a decrease in PCO2 = __#2__
- faster breathing
2. slower breathing
Our drive to breathe (4):
- CO2 levels whether low or high
- more chemoreceptors in body for CO2
- concentration gradients are typically held in narrow range
- more mechanisms to transport CO2
air flow to the alveoli
alveoli ventilation
blood flow to the alveoli
alveolar perfusion
matching ____ and _____ to the alveoli is important for efficient gas exchange in the lungs
ventilation and perfusion
