CHAPTER 23 THE RESPIRATORY SYSTEM
I. ANATOMY OF THE RESPIRATORY SYSTEM
A.
Nose
1.
Functions
a.
air passageway
b.
hairs to trap large particles
c.
moistens
d.
adjusts inhaled air to body temperature
e.
resonance chamber for speech
2.
Nasal cavity
a.
sphenoid, ethmoid - roof
b.
hard and soft palate - floor
3.
Respiratory mucosa
a.
pseudostratified ciliated columnar epithelium
below
epiglottis and stratified squamous above
b.
goblet cells
c.
mucous cells- secrete mucus
d.
serous cells- secrete watery fluid
e.
secretions include lysozyme
1.
antibacterial enzyme
f. ciliated cells important in moving
substances over the surface -"up the mucous elevator"
Why
would this be an important function?
The
cilia is damaged by smokers. What is
the
result?
B.
Paranasal Sinuses
1.
Location within skull bones
a.
frontal
b.
sphenoid
c.
ethmoid
d.
maxillary
2.
Functions
a.
lighten skull
b.
resonance chambers for speech
c.
moisten and warms air
3.
Infections of nasal mucosa
C.
Pharynx (throat)
1.
common to respiratory and digestive systems
2.
connects
a.
nasal cavity/larynx
b.
mouth/esophagus
3.
divided into regions
a.
nasopharynx
1.
superior region-connects with nasal cavity
2.
uvula
a.
closing of nasal cavity with swallowing
3.
pharyngeal tosnils (same as adenoids)
a.
can obstruct air movement if swollen
b.
oropharynx
1.
fauces
a.
opening to mouth
b.
palatine tonsils laterally
c.
lingual tonsils at base of tongue
c.
laryngopharynx
1.
common passageway for food and air
2.
posterior to the epiglottis at base of tongue
D.
Larynx
1.
attaches to hyoid bone
2.
at 4th to 6th vertebra
3.
connects laryngopharynx with trachea
4.
functions
a.
provides open airway
b.
routes food or air traffic
5.
Adam's apple - laryngeal prominence
a.
this is the center of the thyroid cartilage
6.
Cricoid cartilage attaches to trachea
7.
Epiglottis - at base of tongue
a.
not hyaline but elastic cartilage
b.
mucosal covering contains taste buds
c.
tips over larynx opening with swallowing
1.
this routes food/water to esophagus
d.
cough reflex if food/water enters
8.
Vocal Cords
a.
vocal folds
1.
true vocal cords
2.
mucosal folds
3.
glottis is opening between folds
4.
supported by vocal ligaments
b.
vestiblar folds
1.
false vocarl cords
2.
give support to the true vocal cords
c. function in voice
1.
laryngeal muscles produce tension on
the
folds and they vibrate faster for a higher pitch
2.
glottis is wide for deep tone
3.
glottis is narrow for high pitched tones
4.
vocal cords thicken and elongate with
male puberty to
deepen voice
d.
Laryngitis
1.
inflammation of vocal cords
E.
Trachea (windpipe)
1.
Anterior to esophagus
2.
4" long 1" diameter
3.
C-shaped rings of cartilage
a.
opening of C posterior to allow expansion of
esophagus
b.
supported by connective tissue
4.
carina
a.
where trachea divides into left and right branches
b.
particles reaching this point trigger a violent
coughing
attack
5.
Heimlich maneuver
a.
uses lung's air to pop out obstruction
F.
Bronchial Tree
1.
air passageway through lungs
2.
Left and Right primary bronchi
a.
from carina
3.
branching continues in 'orders' 23 times
a.
fractal arrangement
b.
Secondary bronchi
1.
3 right (3 right lobes)
2.
2 left (2 left lobes)
c.
bronchioles
1.
smallest at less than 1 mm
2.
terminal bronchioles - feed into respiratory
bronchioles
4.
Respiratory zone
a.
respiratory bronchioles
b.
last order
c.
less elastin more smooth muscle
d.
no ciliated or mucous cells
(macrophages
in alveoli to cleanse)
e.
respiratory bronchioles
1.
for gas exchange
2.
branch to alveolar ducts
f.
alveolar sacs (alveoli)
1.
pouches off the sides of the duct
2.
air pockets
3.
described as grapelike clusters
4.
Surfactant
a.special epithelial cells (Type II
cells) secrete surfactant to coat alveolar surface
b.
a lipid/protein secretion
c. decreases
surface tension of alveolar fluid so that alveoli do not collapse (water molecule cohesiveness is lessened)
c.Premature
infants do not secrete adequate surfactant
5.
Macrophages present to clean up
G.
Lungs
1.
Left lung
a.
smaller
b.
cardiac notch in concave region for heart
c.
2 lobes - superior and inferior
1.
separated by oblique fissure
2.
Right lung
a.
larger
b.
three lobes
1.
superior(upper), middle, inferior(lower)
2.
oblique and horizontal fissure
3.
Bronchiole tree distributed throught with branching
of
pulmonary artery and veins
4.
branches of aorta: bronchiole arteries supply
lung
with oxygenated blood
5.
Stroma
a.
elastic CT
b.
soft and spongy
H.
Pleura
1.
parietal - outer covering
2.
visceral - outer lining
3.
pleural fluid
a.
serous (watery) to lubricate lung and
create
surface tension between lobes
4.
pleurisy is inflammation of pleura
II. Breathing (Pulmonary Ventilation)
A.
Pressures
1.
Air movement as with other substances is
from
area of HIGH PRESSURE to area of LOW PRESSURE
2.
Phases
a.
Inspiration: air moves into lungs
b.
Expiration: air moves out of lungs
3.
Pressures given are relative to atmospheric pressure
a.
760mmHg (760torr) standard at sealevel
b.
ex. -2mmHg means pressure is 2mmHg less than
atmospheric
pressure and +2mmHg indicates greater
4.
Intrapulmonary pressure
a.
pressure in alveoli that changes with breathing
5.
Intrapleural plessure
a.
pressure in pleural cavity
b.
always 4mmHg less than in alveoli (negative)
c.
factors to keep lungs to wall of thorax:
1.
surface tension (pleural fluid)
lungs
slide over each lobe easily but
don't
pull together
2.
atmospheric pressure in lungs(not alveoli)
push
out
3. external thorax - atmospheric
pressure pushes wall inward to lungs
d.
factors to pull lungs away from thorax wall
1.
recoil due to elasticity of lungs
2. surface tension inside alveoli to pull
in to smallest size but do not collapse
e.
pneumothorax
1.
air in the chest cavity (puncture)
2.
collapses lung
3. no ventilation possible because pressures
are all atmospheric
6.
Boyle's Law
a.Ideal
Gas Law
1. pressure of a gas varies inversely
with its volume when temperature is constant
P1V1=P2V2
What
happens to each when one increases or decreases?
b.
gas molecules far apart (take shape of container)
1.
increase pressure molecules pushed closer
7.
Inspiration
a.
diaphragm contracts
1.
moves inferiorly - flattens
b.
external intercostal muscles contract
1.
elevates rib cage
2.
sternum moves anteriorly
3.
chest expands - increases volume
4. creates a low pressure inside so
that air moves in (-1mmHg intrapulmonary pres.)
c.
forced inspiration
1.
accessory muscles give greater expansion
a.
scalenes
b.
sternocleidomastoid
c.
pectoral
d.
erector spinae group
8.
Expiration
a.
normally passive
1.
recoil of lungs
2.
relaxation of inspiratory muscles decrease
thoracic volume and raise intrapulmonary
pressure 1mmHg - air moves out
b.forced
expiration
1.
active process
2.
accessory muscles
a.
transversus and obliques
b.
internal intercostal
c.
latissimus dorsi
3.
contraction of these decrease thoracic
volume
to increase pressure for air to move
outward
C.
Factors influencing ventilation
1.
resistance
a.
friction
b.
as resistance increases air flow decreases
c.constriction
of bronchioles (bronchioconstriction)
1.
parasympathetic
2.
asthma attacks
3.
many chemicals act to constrict
d.
dialation (bronchiodilation)
2.
sympathetic stimulation
a.
to increase respiratory rate
in
flight-or fight response
b.
these are beta2 adrenergic receptors
c.
caution: beta-blockers could prevent this dilation
2.
Compliance
a.
distensibility - important in inspiration
1.
ease of expansion
2.
depends on volume and pressure
3.
C=changein lung volume /change in pressure
Compare
2 lungs: A has greater change in volume than B at the same pressure? Which is
more compliant?
3.
Elasticity
a.
recoil for normal expiration
b.
decreases with emphysema
4.
Surface Tension
a. molecules in a liquid surface
attract and separate from the gas thus reducing molecule contact with gas
b.
surfactant
1.
detergent-like lipoprotein produced by alveolar cells
2.
decreases cohesiveness of water molecules
D.
Lung Volumes and Capacities
1.
Tidal Volume (TV)
a.
amount of air that moves in and out of
the
lungs during normal breathing
b.
about 500ml
2.
Inspiratory Reserve Volume (IRV)
a.
amount of air that can be forcefully
inhaled,
above TV
3.
Inspiratory Capacity = TV + IRV
4.
Expiratory Reserve Volume (ERV)
a.
amount that can be forcefully exhaled
beyond
the TV
5.
Residual Volume (RV)
a.
remains in lungs after forceful expiration
6.
Functional Residual Capacity (FRV)
a.
amount remaining in lungs after TV
b.
ERV +RV
7.
Vital Capacity
a. TV +IRV + ERV
b.
exchangable volume
8.
Total Lung Capacity
a.
TV + IRV +ERV + RV
b.
6000ml in males, less in females
9.
Dead Space
a.
air that fills the passageways but not
exchanging
gases at alveoli
b.
about 150 ml
10.
PFT - Pulmonary Function Tests
a.
spirometer
b.
evaluates losses in respiratory function
c. obstructive pulmonary disease
1.
increased airway resistance
a.
ex. asthma
2.
increases in TLC, FRC, and RV
3.
hyperinflation of lung
d.
restrictive disorders
1.
structural or functional changes in lungs
2.
ex. TB
3.
VC, TLC, FRC, and RV reduced
11.
MRV - minute respiratory volume
a.air
flow in and out of lungs per minute
b.
6 L/min with TV of 500 ml
at
RR of 12 breaths per min
12.
alveolar ventilation rate (AVR)
a.
effective ventilation
AVR
= RR x (TV-dead space)
b.
amount reaches alveoli
III. Gas Exchange
A.
Properties of Gases
1.
Dalton's law of partial pressures
a.
total pressure exerted by a mixture of gases
is
the sum of the pressures exerted by each
gas
in the mixture
a.
Nitrogen - 79% of atm, 597mmHg ATM = partial pressure (P)
b.
Oxygen 21% of atm, 159 mmHg ATM
c.
Carbon Dioxide 0.04%, 0.3 mmHg ATM
d.
Water Vapor 0.46% , 3.7 mmHg ATM
e.
Total pressure = 760 mmHg ATM
f.
Water vapor and Carbon dioxide have higher
partial
pressures in the alveoli
g.
Nitrogen and Oxygen have lower P in alveoli
than atmosphere
What
do the partial pressures of the gases tell you about
which
way the gases will diffuse?
2.
Henry's Law
a.
each gas in a mixture will dissolve in a liquid
dependent
upon its partial pressure gradient
until
equilibrium
B.
Hyperbaric oxygen
1.
chambers to provide higher than atmospheric pressure
of
oxygen to aid treatment of certain oxygen
dependent
disorders
2.
ex. gas gangrene, tetanus (anaerobic organisms)
carbon monoxide poisoning, circulatory
shock,
3.
generate harmful amounts of oxygen free radicals
and
can cause oxygen toxicity effects
C.
Factors Influencing gas exchange
1.
partial pressure gradients
a.
PO2 of pulmonary blood 40 mm Hg
b.
PO2 of 104 mmHg in alveoli
c.
diffuse intil 104 mmHg on both sides
d. PCO2 40 mmHg in alveoli
e.
PCO2 45 mmHg in pulmonary blood
2.
Structure of respiratory membrane
a.
between alveoli and pulmonary capillaries
b.
thicken (as with edema) longer time to diffuse
c.
more surface area the faster diffusion
1.
many alveolar sacs
3.
match between ventilation rate and blood flow to lungs
4.
gas exchange at capillaries and cells:
a.
reversed partial pressure gradients
b.
driven by partial pressure gradients and
diffusion
D.
Transport of Respiratory Gases in BLood
1.
Oxygen
a.
bound to heme of hemoglobin
1.
oxyhemoglobin
a.
delivers oxygen to tissues
b.
dissolved oxygen
c.
Oxygen-hemoglobin dissociation curve
DRAW from
page 750
1.When
all four of the heme groups are
bound
with oxygen it is fully saturated
2.
% Saturation of hemeglobin with oxygen
is
dependent on Po2 in blood/tissues
Saturation
is 75% in venous blood
3.
temperature affects saturation
cold
: Hb holds oxygen tighter
and
Hb dissociation curve shifts to left
warm
(ex. working muscles) require more
oxygen
and Hb releases more oxygen
as
temp. increases increase temp shifts
curve
to right and oxygen is easily
released
4. CO2 lowers blood pH
(acts to increase H ions with buffering) and Hb saturation
curve
shifts to right.
Working
muscles will need more ATP, if not
enough
oxygen pH decreases (acidosis) so
desire
this result to aid release of oxygen
from
hemoglobin
Bohr
effect: acid decreases binding affinity of Hb and oxygen
5.
no mitochondria in RBCs but release
DPG
)2,3- diphosphoglycerate formed from
glycolysis
within RBC . This more DPG
enhances
release of oxygen from heme
a.
hormones can have effect of increasing
metabolic
rate of RBC (more DPG) and enhance
delivery
of oxygen to tissues
e.
Hypoxia
1.
low oxygen delivery to tissues
2.
can result from ischemia, anemia
pulmonary
disease
3
carbon monoxide poisoning
1.
Hb binds CO instead of O2
2.
Carbon Dioxide transport
a.
Dissolved in plasma 10%
b.
bound to hemoglobin 25%
c.
as bicarbonate ion in plasma 65%
HCO3-
d.
Carbonic acid/ bicarbonate ion buffer system
Write
equation:
e. fast reaction in RBC due to enzyme
carbonic anhydrase that converts carbon dioxide and water to carbonic acid
and
also the reverse reaction to liberate carbon dioxide
1.
Chloride shift
a.
chloride ions move
in
when bicarbonate ions leave to balance
f.
Haldane effect
IV. Control of Respiration
A.
medulla : respiratory center
1.
inspiratory center -dorsal respiratory group
a.
phrenic innervation to diaphragm
b.
intercostal nerve
c.
eupnea - normal rate and rhythm
2.
expiratory center- ventral respiratory group
a,
keeps inspiratory muscles slightly contracted
b.
recruits expiratory muscles as needed
B.
Pons
1.
pneumotaxic center
a.
inhibitory impulses to inspiratory center
b.
yields short,rapid breaths
2.
apneustic center
a.
hold breath with inspiration
b.
yields deep, slow breathing
C.
Factors affecting rate
1.
receptors for irritants
a.
cough, constriction
2.
Hering-Breuer Reflex
a.
stretch receptors
b.
prevents over stretching of lungs
3.
Hypothalamus - autonomic nervous system
4.
chemoreceptors
a.
Carbon dioxide
1.
central in medulla
2.
peripheral
3.
hypercapnia - high carbon dioxide levels
want
to blow off more so increase RR
hyperventilation
4.
hyperventilation can therefore also result
in
lowering carbon dioxide to far or hypocapnia
5.
apnea - breathing cessation
b.
oxygen
1.
carotid bodies
2.
aortic arch
3.
sense low oxygen tension
c.
pH
1. decrease in pH or increase in
hydrogen
ion concentration separate
from
influence of carbon dioxide will
stimulate
respiration
5.
exercise
a.
hyperpnea
1.
deeper breathing
b.
increase in ventilation not result of
chemicals,
other neural control
6.
altitude
a.
acclimatization
b.
Po2 is less
c.
respond by increasing RBC production
V. Disorders
A.
Chronic Obstructive Pulmonary Disease (COPD)
1.
Emphysema
a.
enlargement of alveoli
b.
deterioration of alveolar wall
c.
fibrosis of lung
1.
less elasticity
2.
airways collapse with breathing
d.bronchioles
collapse during expiration
and
air is trapped in alveoli - barrel chest
e.
not cyanotic until disease progresses
2.
bronchitis
a.
excessive mucus
b.
block airways
B.
Lung Cancer
1.
1/3 cancer deaths in US
2.
clearly associated with cigarette smoking
3.
irritation, loss of cilia
4.
mucosal cells lose histological sturcture and proliferate
5.
removal of disease part
VI. Developmental
A.
Gas exchange via placenta not lungs
B.
Vascular shunts bypass lungs
C.
Fetal lungs filled with fluid
D.
Baby takes first breath in response to increases
in
blood carbon dioxide
E.
Developmental abnormalities
1.
cleft palate - structural abnormalities
2.
cystic fibrosis
a.
oversecretion of mucus - a genetic
abnormality
3.
RR = newborn 40-80/min
infants
30/min
END