hlsc 128 Flashcards
respiratory system
main function of respiratory system?
supply body tissues with 02 and dispose of co2 generated by cellular metabolism
how many processes does the respiratory system encompass are they related and are they separate and what are they called
-2
-internal respiration
-external respiration
-seperate but related
what is external respiration
exchange of o2 and co2 between the external environment and cells of the body
how many steps in external respiration and what are they
4 steps
-ventilation : movement of air in and out of the lungs
-o2 and co2 exchange between air in the alveoli and blood within the
pulmonary capillaries
-blood transports o2 and co2 between lungs and tissues
-o2 and co2 exchanged between tissues and blood by diffusion across systemic capillaries
what does the respiratory system consist of ?
- respiratory airways leading into lungs
- lungs (airways and alveoli)
-structures of the thorax involved in air movement through the airways into and out of the lungs
what occupies most of thoracic cavity ?
the lungs
what are the two lungs divided into and what is each on supplied by
divided into several lobes and each one is supplied by one of the bronchi
what are some characteristics of the lungs and what do they contain
-highly branched airways
-the alveoli
the pulmonary blood vessels
-and large quantities of elastic connective tissue
what do the respiratory airways do
they are tubes that carry air between the atmosphere and the air sacs
what are the respiratory airways
-nasal passages /nose
-pharynx /common passageway for respiratory digestive systems
-trachea/windpipe
-larynx /voice box
-right and left bronchi
do bronchioles contain cartilage to hold them open
no cartilage to hold them open
what do bronchioles walls contain and innervated by what
contain smooth muscle innervated by the autonomic nervous system
what are the bronchioles sensitive to
hormones and local chemicals
where are the alveoli located in the bronchioles
they are clustered at ends of terminal bronchioles
what are the trachea and larger bronchi called
convection zone
how does the convection zone prevent collapse
by rings of cartilage
a description of the convection zone
fairly rigid, nonvascular tubes
where is the diffusion zone
bronchioles
what are alveoli
thin walled inflatable sacs
what are the function of alveoli
-gas exchange
-large surface area
what is type 1 alveolar cells consist of
wall consist of a single layer of flattened epithelial cells
what do pulmonary capillaries do
encircle each alveolus
what do type 2 alveolar cells secrete
pulmonary surfactant
what do alveolar macrophages do
they guard the lumen
what do pores of kohn do
permit airflow between adjacent alveoli (collateral ventilation)
what is the outer chest wall called
thorax
how is the thorax formed
by 12 pairs of ribs
how do the sternum and thoracic vertebrae face the thorax
-sternum anteriorly
-thoracic vertebrae posteriorly
what does the ribcage do
protects the lungs and the heart
what do the muscles in the thorax do
involved in generating pressure that cause airflow
what are the main inspiratory muscles
-diaphragm
-external intercostal muscles
what is the structure of the diaphragm
-dome shaped sheet of skeletal muscle
what does the diaphragm do
separates the thoracic cavity from abdominal cavity
what is the diaphragm innervated by
phrenic nerve
what is the external intercostal muscles innervated by
intercostal nerve
what do the expiratory muscles contain
-internal intercostals
-abdominal muscles
what do the abdominal muscles contain
-rectus abdominis
-transverse abdominis
-internal and external obliques
what is the pleural sac or the serousal membrane
-double walled, closed sac that separates each lung from the thoracic wall
what is the pleural cavity
the interior of plural sac
what is inter pleural fluid and what is it secreted by
-secreted by the pleura
-lubricates the pleural surfaces
what does the pleural sac form and how many ml
form a thin double layered serosa that is a few ml
what is the parietal membrane
thoracic wall and superior face of the diaphragm
viceral membrane what is it
external surface of the lung
what does pleural sac allow to happen during breathing
allows lungs and thorax to slide past each other during breathing
how does air enter and leave the lungs
by respiratory mechanics
pressure differences
f =p/r
what’s important in ventilation
interrelationships among pressures inside and outside the lungs
how many different pressure considerations is there what are they called and what are they important in
4
-atmospheric (barometric pressure)
-intraalveolar pressure
-intraplural pressure
-transpulmonary pressure ( inside - outside pressure)
important in ventilation
respiratory pressures are always relative to what
atmospheric pressure
measure in what
mmhg
cmh20
atmospheres (atm)
how much do pressures equate at sea level
mmhg =760
atm=1
cmh20 =1034
at higher altitudes would pressures be higher or less than sea level
less than sea level
what are highly distensible and have elastic recoil
lungs
what is more rigid than lungs and recoils outward
thoracic wall
what is transmural pressure
inside pressure - outside pressure
what keeps lung and chest wall together
transmural pressure gradient
what always has sub atmospheric pressure
pleural sac
source of lungs elastic recoil
1-strechability
2-alveolar surface tension thin liquid films lines each alveolus
what do water lined alveoli creates and what does this cause
surface tension
-resists alveoli expansion -less compliant
-tends to shrink alveoli - recoil
what would happen to lungs if only water lined alveoli
they would collapse
if the alveoli is smaller what happens to the surface tension
surface tension is greater the smaller the alveoli which causes collapse
what reduces surface tension
pulmonary surfactant
how does pulmonary surfactant reduce surface tension
-reduces cohesive force between water molecules
-deep breathing increases secretion by stretching type 2 cells
what is pulmonary surfactant made of
a complex mixture of phospholipids and proteins
what are the benefits of pulmonary surfactant
- reduces work of the lungs
- reduces recoil pressure of smaller alveoli more than larger alveoli
why do premature babies have difficulty breathing
lack of pulmonary surfactant
what does alveolar interdependence contribute to
alveolar stability
how are alveoli connected
by connective tissues
what happens if an alveolus begins too collapse
neighbouring alveoli resist by recoiling
what forces keep alveoli open
positive transmural pressure
pulmonary surfactant
alveolar interdependence
wat forces promote alveolar collapse
elasticity of stretched connected tissue fibres
alveolar surface tension
what is pneumothorax
its an abnormal condition when air enters the pleural space
what happens to pleural and alveolar pressure during pneumothorax
both pleural and alveolar pressure now equal atmospheric pressure, therefore pressure gradient no longer exits across lung or chest wall
what happens to lung when there’s no opposing negative pleural pressure to keep it inflated
collapses to its unstretched size
boyles law
at any constant temperature the pressure exterted by a gas varies inversely with the volume of a gas
what does change in alveolar pressure do
produces flow of air in and out of the lungs
what happens if alveolar pressure is less than atmospheric pressure
air enters the lungs
what happens if alveolar pressure is greater than atmospheric pressure
air exits the lungs
what is boyles law
p1v1=p2v2
what happens when lung volume is altered
pressure changes in the lungs
airflow is generated
what happens in respiratory muscle
activity change volume of thoracic cavity
expansion during inspiration decreases what
intra pleural pressure
what is the primary determinant of resistance to airflow
radius of airways
what controls the contraction of smooth muscle in airway walls aka changes the radii
autonomic nervous system
which branches of the autonomic nervous system act on airway smooth muscle
both SNS and PNS
SNS causes what
causes bronchodilaton by NE and Epinephrine
PNS causes what
bronchoconstriction by ACh
what happens when someone has chronic pulmonary disease
abnormally increases airway resistance
when is expiration more difficult than inspiration
during chronic pulmonary diseases
what are some diseases that affect airway resistance
-chronic bronchitis
-emphysema
-asthma
what does a spirometer contain
an air filled drum floating in a water filled chamber
what is the maximum volume of lungs in adult male and adult female
male 5.7 L
female 4.2 L
how much do lungs contain at reset
2.2 L after expiration still half full
tidal volume Vt
500 mL
inpiratory reserve volume IRV
3000mL
inpiratory capacity IC
3500mL
exploratory reserve volume ERV
1000mL
Residual volume RV
1200mL
functional residual capacity FRC
2200 mL
vital capacity VC
4500 mL
total lung capacity TLC
5700 mL
what is tidal volume
volume of air entering or leaving lungs during a single breath 500 mL
Residual volume what is it
minimum volume of air remaining in the lungs even after a maximal expiration 1200 ml
what is vital capacity
maximum volume of air that can be moved out during a single breath following a maximal inspiration VC = IRV+TV+ERV 4500 mL
total lung capacity TLC what is it
maximum volume of air that the lungs can hold 5700 mL
what gives abnormal spirometry results
-obstructive lung disease : •increased airway resistance •FEV1<80% forced exploratory volume in one second
-restrictive lung disease : •normal airway resistance but reduced vital capacity •impaired respiratory movements •abnormalities in lung tissues
•the pleura
•chest wall
•neuromuscular machinery
pulmonary ventilation equals what
minute ventilation
what is pulmonary ventilation
volume of air breathed in and out in one minute
what is the pulmonary ventilation equation
pulmonary ventilation (6000mL/min)= tidal volume (500 mL / breath) x respiratory rate (12breaths/min)
what more important alveolar ventilation or pulmonary ventilation
alveolar ventilation
what is alveolar ventilation
volume of air exchanged between atmosphere and the alveoli per minute
why is alveolar ventilation less than pulmonary ventilation
due to anatomic dead space
alveolar ventilation equation
(tidal volume - dead space )x respiratory rate
how much does quiet breathing of total energy expenditure require
3%
when is work of breathing increased
-when there is a need for increased ventilation example exercise 10-15 O2 consumption
-when pulmonary compliance is decreased eg fibrosis
-when elastic recoils is decreased example emphysema
what is gas exchange
-simple diffusion of O2 and CO2 down partial pressure gradient
-until partial pressures are equilibrated
