Download Respiration

22 The Respiratory System
Respiration
• function - supply body with O2 and dispose of CO2
• respiration - process of gas exchange between the
atmosphere and cells
throat
voicebox
windpipe
*gas exchange
a. pulmonary ventilation (breathing) - movement of
air into and out of the lungs
b. external respiration - gas exchange between the
blood and air in lungs (O2 in, CO2 out)
c. gas transport - blood carries O2 to tissue cells and
picks up CO2
d. internal respiration - gas exchange between
blood and body cells (O2 out, CO2 in)
• also involved in the sense of smell and with speech
*breathing
external respiration - O2 into blood, CO2 into lungs
gas transport - O2 and CO2 ride the blood bus
pulmonary ventiliation
internal respiration - O2 into cells, CO2 out of cells
WHY DO OUR CELLS NEED OXYGEN??????
*O2 is the golden ticket into the mitochondria where we make ATP!
22 The Respiratory System
Respiratory Tract
upper
• functional divisions
respiratory tract
a. respiratory zone - site of gas exchange
includes bronchioles, alveolar ducts, alveoli
b. conducting zone - allow air to reach respiratory zone
includes nose, nasal cavity, paranasal sinuses,
pharynx, larynx, trachea, bronchi, lungs
lower
respiratory tract
• structural divisions
a. upper tract
includes nose, nasal cavity, paranasal sinuses, pharynx
strep throat, colds, allergies, sinus infection
b. lower tract
includes larynx, trachea, bronchial tree, lungs
pneumonia, laryngitis, bronchitis
High Card Wins...Best 2 out of 3
*movement of air
*gas exchange
RIGHT
Winner...What are the 4 processes of respiration?
Nonwinner...What's happening at each step?
external respiration
internal respiration
LEFT
Right...Differentiate between upper and lower respiratory tracts.
Left...Differentiate between conducting and respiratory zones.
22 The Respiratory System
1 ____ refers to the process of normal
breathing.
2 ____ means gas exchange.
A
Ventilation
A
pulmonary ventilation
B
Respiration
B
internal respiration
C
Pulmonary
C
external respiration
D
Inspiration
D
cellular respiration
3 All of the following are part of the upper
respiratory system EXCEPT
4 MATA: The respiratory zone
A
starts with the nose and mouth
A
nasal cavity
B
is where gas exchange occurs
B
pharynx
C
includes the bronchioles and alveoli
C
trachea
D
warms, moistens, and filters
incoming air
D
nares
Nose & Nasal Cavity
• functions - produce mucus, filter, warm, and moisten
incoming air, resonating chamber for speech, houses
olfactory (smell) receptors
• nose
bone and cartilage support nose internally
nostrils (nares) provide openings for air to pass
hairs prevent entry of large particles
• nasal cavity
nasal septum divides cavity into right and left
nasal conchae creates passageways, supports
mucous membranes, increases surface area
receptors for smell
*****
22 The Respiratory System
Mucous Membranes
• mucous - structure that secretes mucus
• mucus - sticky substance
• pseudostratified ciliated epithelium
lining nose and nasal cavity
• extensive network of blood vessels
• air passing over membrane is heated to
within 1 of body temperature (98.6 F) by
blood vessels
• air is moistened as water evaporates
from membrane
• sticky mucus traps dust and other small particles
• cilia push a thin layer of mucus with entrapped particles
toward pharynx (throat)
Paranasal Sinuses
• functions - same as nose and nasal cavity, lighten
skull
• air-filled spaces located within the maxilla, frontal,
ethmoid, and sphenoid bones
• open to nasal cavity
• mucous membrane lines sinuses and are continuous
with nasal cavity
swallowed - stomach acid destroys microorganisms
expectorated - spit or blown out
• sensory nerve endings trigger a sneeze when they come in
contact with an irritant
*warm, moisten, filter!!!
Pharynx
...Upper respiratory tract structure and function.
• functions: passageway for food/liquid to esophagus
and air to larynx
• commonly referred to as the throat
• passageway connecting nasal cavity to larynx and
oral cavity to esophagus
• three divisions: nasopharynx (behind nose),
oropharynx (behind mouth), laryngopharynx/
hypopharynx (behind larynx)
lower
respiratory tract
5 The ____ is a passageway for both air
and food/liquid.
6 MATA: The mucous membranes function
to
A warm incoming air
A
Nares
B
moisten incoming air
B
Nasal conchae
C
filter incoming air
C
Sinuses
D
deionize incoming air
D
Pharynx
22 The Respiratory System
Larynx
• functions - air passageway, prevents food from
entering lower respiratory tract, voice production
• commonly referred to as the voice box
• composed of muscle and cartilage bound by
elastic tissue
Vocal Cords, Glottis, & Epiglottis
• vocal cords housed in larynx
false vocal cords - upper pair of folds within larynx
produces NO sound, but help close airway during
swallowing
true vocal cords - lower pair of folds in larynx
produces sound through vibration
• glottis - triangular slit/opening in vocal cords
muscles in false vocal cords close glottis when
swallowing
• epiglottis - flaplike structure that closes over larynx
during swallowing to prevent food/liquid from
entering airways
Trachea
• functions - air passageway, cleans, warms, and
moistens incoming air
• commonly referred to as the windpipe
• flexible, cylindrical tube about 2 cm in diameter and
10-12 cm in length
• extends downward in front of esophagus into
thoracic cavity
• splits into right and left bronchi
• about 20 C-shaped pieces of hyaline cartilage keep
trachea from collapsing
• backside composed of smooth muscle and
connective tissue to allow esophagus to expand
when swallowing food
Bronchial Tree
• functions - air passageways connecting trachea with
alveoli; cleans, warms and moistens incoming air
• branched airways leading from the trachea to the
microscopic air sacs (alveoli) of the lungs
• cartilage line bronchial tree (like trachea), but as
branching gets smaller smooth muscle becomes
more prominent
• primary bronchi
secondary bronchi
bronchioles
alveolar ducts
alveolar sacs
alveoli
• alveoli - simple squamous epithelial cells through
which gases can easily be exchanged (diffusion)
increase surface area of lungs (1/2 size of a tennis court)
about 300 million
22 The Respiratory System
*site of external respiration
*segmental bronchi keep dividing into smaller and
smaller tubes eventually called terminal bronchioles
Lungs & Pleurae
...Lower respiratory
soft, spongy, cone-shaped organs in thoracic cavity
mediastinum - separates right and left lung
diaphragm - muscle underneath lungs
suspended by a bronchus and some large blood
vessels
• pleurae - membrane that surrounds each lung
•
•
•
•
tract structure and
function.
serous fluid in between the membranes reduces
friction while breathing
• right lung is larger and divided
into 3 lobes
• left lung is smaller and divided
into 2 lobes
7 MATA: Protective structures of the
respiratory system include the
8 Gas exchange occurs in the
A
trachea
glottis
B
bronchi
B
nasal conchae
C
bronchioles
C
epiglottis
D
alveoli
D
tracheal cartilage
A
22 The Respiratory System
Respiration Review
Mechanics of Breathing
Pulmonary Ventilation
• respiration - process of gas exchange between the
atmosphere and cells
a. pulmonary ventilation (breathing) - movement of
air into and out of the lungs
• 2 phases
inspiration - air flows into lungs (inhale)
expiration - gases exit lungs (exhale)
• nonrespiratory movements - voluntary or reflexive
movement of air into and out of the lungs
coughing, sneezing, laughing, crying, hiccups,
and yawning
WHAT INCREASES
Pressure Relationships in the Thoracic Cavity
• atmospheric pressure (Patm) - pressure
exerted by the air surrounding the body
Patm = 760 mm Hg at sea level
negative respiratory pressure is
lower than 760 mm Hg
positive respiratory pressure is
higher than 760 mm Hg
• intrapulmonary pressure (Ppul) - pressure
in alveoli
rises and falls with phases of breathing
• intrapleural pressure (Pip) - pressure in pleural cavity
rises and falls with phases of breathing
ALWAYS negative (about -4 mm Hg) relative to Ppul
• transpulmonary pressure - difference between intrapulmonary
and intrapleural pressures (Ppul - Pip)
partial vaccum keeps lungs from collapsing
INTRAPULMONARY
PRESSURE?
fluid, air, or tumor
X-ray of collapsed lung
What's this?
CYST
CT scan
Boyle's Law
at constant temperature...
PV = P V
1
1
where,
P = pressure of a gas
V = volume
1 = initial conditions
2 = resulting conditions
• pressure of a gas varies
inversely with its volume
2
2
Inspiration
• normal inhale = quiet inspiration
moves about 500 mL of air into lungs
• inspiratory muscles increase
intrapulmonary volume
diaphragm - contracts and flattens
external intercostal muscles - elevate
ribs and sternum
• as volume increases, Ppul decreases about
1 mm Hg relative to Patm
• anytime Ppul is less than Patm air rushes into
the lungs until the two are equal
• Pip decreases to -6 mm Hg relative to Patm
• deep or forced inspiration = accessory
muscles increase volume further
22 The Respiratory System
Sequence of Events - Inspiration
1. inspiratory muscles (diaphragm and external
intercostals) contract
2. thoracic cavity volume increases
3. intrapulmonary pressure drops (-1 mm Hg)
4. air flows into lungs
Sequence of Events - Expiration
1. inspiratory muscles relax
2. thoracic cavity volume decreases
3. intrapulmonary pressure rises (1 mm Hg)
4. air rushes out of lungs
Expiration
• normal exhale = quiet expiration
• passive process dependent on elastic
recoil of lung and thoracic wall tissue
• when inspiratory muscles relax, lungs return
to original/resting state
• volume decreases, Ppul increases about 1
mm Hg above Patm
• anytime Ppul is greater than Patm air is forced
out of the lungs until the two are equal
• forced expiration (deep exhale) is an
active process that relies on contraction of
the abdominal wall (pushes diaphragm
higher into lungs) and internal intercostals
(pull rib and sternum down and in) to
further decrease lung volume
Best 2 out of 3
ICH
Pull
OES THE
WORK?
NONWINNER...Review the process of inspiration.
WINNER...Review the process of expiration.
22 The Respiratory System
1 MATA: Inspiration occurs when
A
the diaphragm relaxes
B
the thoracic cage expands
C
when intrapulmonary pressure is less
than atmospheric pressure
D
air enters lungs
3 MATA: Pressure in the lungs increases
A
during expiration
B
when lung volume decreases
C
when the diaphragm relaxes
D
forcing air out
2 Intrapleural pressure should always be
negative (less than atmospheric) to
prevent the lungs from collapsing.
True
False
Introduction to Lung Volumes
normal breathing
always there (reserve)
WHAT HAPPENS WHEN YOU GET THE
deep inhale
WIND KNOCKED OUT OF YOU?
Hmm...
normal
breathing
deep exhale
Pull
always there
(reserve)
22 The Respiratory System
Respiratory Capacities
• specific combinations of respiratory volumes
• inspiratory capacity (IC) = 2400-3600 mL
maximum amount of air that can be inspired after a
normal expiration
IC = TV + IRV
• functional residual capacity (FRC) = 1800-2400 mL
volume of air remaining in the lungs after a normal tidal
volume expiration
FRC = ERV + RV
• vital capacity (VC) = 3100-4800 mL
maximum amount of air that can be expired after a
maximum inspiratory effort
VC = TV + IRV + ERV
• total lung capacity (TLC) = 4200-6000 mL
maximum amount of air contained in the lungs
TLC = TV + IRV + ERV + RV
Respiratory Volumes
• different intensities of breathing move different volumes
of air into and our of the lungs (respiratory volumes)
• normal inspiration = about 500 mL
• normal expiration = about 500 mL
• tidal volume (TV) = 500 mL
amount of air that moves into and out of the lungs during
quiet breathing
• inspiratory reserve volume (IRV) = 1900-3100 mL
amount of air that can be forcibly inhaled after normal
tidal volume
• expiratory reserve volume (ERV) = 700- 1200 mL
amount of air that can be forcefully exhaled after a
normal tidal volume exhalation
• residual volume (RV) = 1100-1200 mL
amount of air remaining in the lungs after a forced
exhalation
TALLER...Review the important lung volumes.
SHORTER...What is VC and TLC?
4 ____ refers to the amount of air moving
in and out during quiet breathing.
5 The amount of air that remains in our
lungs after our biggest exhale is called
A
Tidal volume
A
expiratory reserve volume
B
Total lung capcity
B
total lung volume
C
Inspiratory reserve volume
C
minimal lung volume
D
Vital capacity
D
residual lung volume
22 The Respiratory System
Factors Influencing Ventilation
• airway resistance
F = gas flow
P = pressure
R = resistance
WHY DOES
KNOWING
THESE VOLUMES
MATTER?
Gas Exchange & Transport
F=
• alveolar surface tension
P
R
surfactant - mixture of lipids and proteins that
reduces the surface tension of water and prevents
alveoli from collapsing
• lung compliance - lung stretchy-ness
determined by distensibility of lung tissue and
alveolar surface tension
diminished by decreases in lung elasticity
(inflammation or infection) and decreases in
surfactant
Respiration Review
• respiration - process of gas exchange between the
atmosphere and cells
a. pulmonary ventilation (breathing) - movement of
air into and out of the lungs
b. external respiration - gas exchange between the
blood and air in lungs (O2 in, CO2 out) - DIFFUSION
c. gas transport - blood carries O2 to tissue cells and
picks up CO2
d. internal respiration - gas exchange between
blood and body cells (O2 out, CO2 in) - DIFFUSION
Two More Gas Laws
Dalton's Law of Partial Pressures
Dalton's Law of Partial Pressures
LEFT...
• the total pressure exerted by a mixture of gases is the sum of
the pressures exerted independently by each gas in the
mixture
• partial pressure (pressure of each gas) is directly proportional
to the percentage of that gas in the gas mixture
• ex. atmosphere is 21% oxygen
0.21 x 760 mm Hg = 159 mm Hg
PO2 = 159 mm Hg
Henry's Law
• the direction and amount of movement of a gas is
determined by its partial pressure in the two phases (gas and
dissolved in liquid)
• gases move from higher partial pressure to lower partial
pressure until they reach equilibrium
• also affected by solubility of the gas and temperature of the
liquid
CO2 is more soluble than O2, so it dissolves more readily in water
(ex. blood plasma)
What is
Dalton's
Law?
Henry's Law
RIGHT..
What is
Henry's
Law?
22 The Respiratory System
1 ____ law states that gases diffuse from
areas of higher partial pressure to areas
of lower partial pressure.
A
Dalton's
B
Bohr's
C
Henry's
D
Boyle's
Composition of Alveolar
Gas
ATMOSPHERE
N2 - 78.6% and 597 mm Hg
O2 - 20.9% and 159 mm Hg
CO2 - 0.04% and 0.3 mm Hg
H2O - 0.46% and 3.7 mm Hg
ALVEOLI
N2 - 74.9% and 569 mm Hg
O2 - 13.7% and 104 mm Hg
CO2 - 5.2% and 40 mm Hg
H2O - 6.2% and 47 mm Hg
Why the difference?
1. gas exchange occurring in lungs
2. humidification of air by conducting zone
3. mixing of alveolar gas during each breath
External Respiration
Partial Pressures
• O2 loaded into blood, CO2 unload into alveoli
• partial pressure gradients and gas solubilities
driving force of diffusion across respiratory membrane
gases diffuse from regions of higher partial pressure to
regions of lower partial pressure (Henry's Law)
*refer to picture on following slide
• ventilation-perfusion coupling
ventilation = gas reaching alveoli
perfusion = blood flow in pulmonary capillaries
high ventilation = high perfusion
(and vice versa)
ensures efficient gas exchange
• thickness and surface area of
respiratory membrane
2 epithelial cells (1 lining alveolus
& 1 lining capillary) & a fused
basement membrane
a thin respiratory membrane increases
gas exchange efficiency
Ventilation-Perfusion Coupling
mismatch
(inefficient)
stimulus
restored
response
efficiency
NOSE
GOES
22 The Respiratory System
Winner...Explain Henry's Law in
relation to external respiration.
2 MATA: PO2 is ___ in the lungs and ___ in
the blood.
Nonwinner...How does the
structure of the respiratory
membrane support its function?
3 Which structure increases the efficiency
of external respiration?
A
ciliated pseudostratified epithelium
B
capillary minivalves
C
respiratory membrane
D
alveolar surfactant
A
higher, lower
B
lower, higher
O2 Transport
• b/c O2 is poorly soluble in water, blood plasma only
carries about 1.5% of O2 to cells
• 98.5% of O2 is chemically combined with
lungs
hemoglobin (Hb)
HHb + O2
HbO2 + H
oxyhemoglobin - HbO2
tissues
deoxyhemoglobin (reduced) - HHb
loading/unloading equation
• rate at which Hb reversibly binds or releases O2
depends on...
PO2
temperature
= Hb affinity for O2
blood pH
= Hb affinity for O2
PCO2
BGP (2,3-bisphosphoglycerate) concentration
*created during anaerobic respiration in RBCs
Oxyhemoglobin Dissociation Curve
25% to tissues;
Hb unloads more O2
75% stays HbO2
after 1
at rest
trip
50% more to tissues;
through
25% stays HbO2
body
(decreased affinity)
additional O2
unloading to
exercising
tissue
Hb unloads less O2
(increased affinity)
exercising
tissue PO2
at rest
+
22 The Respiratory System
TALLER...How is O2 transported in the blood?
SHORTER...What factors affect O2 unloading?
4 MATA: O2 is transported
5 Which of the following does NOT affect
Hb's affinity for O2?
A
HHb
B
BPG
C
temperature
D
PCO2
CO2 + H2O
loading @ tissues
H2CO3
unloading @ lungs
H + HCO3
+
-
A
attached to hemoglobin
B
in blood plasma
C
connected to platelets
D
from higher partial pressure to lower
partial pressure
Internal Respiration
• O2 unloaded into cells,
CO2 loaded into blood
• accomplished by simple
diffusion driven by the
partial pressure gradients
of O2 and CO2
CO Transport
2
• blood flowing through capillaries picks up CO2 from tissues
with an elevated PCO2
• blood transports CO2 3 ways
7% dissolves in plasma
23% binds to "globin" = carbaminohemoglobin
70% forms bicarbonate ions (HCO3-)
• in RBC, CO2 combines with H2O to form carbonic acid (H2CO3)
• RBCs contain carbonic anhydrase (enzyme) which reversibly
catalyzes these reactions
• carbonic acid then dissociates releasing H+ and HCO3• HCO3- then diffuse back into plasma
chloride shift - HCO3- exchanged for Cl- (balanced
exchange of neg. ions)
• when blood reaches lungs, CO2 diffuses into alveoli due to low
PCO2 in alveolar air
• at the same time HCO3- re-renter RBCs and the reaction reverses
22 The Respiratory System
CO2 + H2O
loading @ tissues
H2CO3
H + HCO3
+
unloading @ lungs
-
6 How does MOST CO2 travel in the blood?
THIS ONE IS
TRICKIER...work
together to explain how
CO2 is transported in
the blood.
Neural Mechanisms
• medullary respiratory centers (medulla
oblongata)
> dorsal respiratory group (DRG) - helps VRG;
still figuring this one out
> used to be called pneumotaxic area
• generation of respiratory rhythm seems to
be autorhythmic, but still figuring this one
out too
combined with hemoglobin
B
dissolved in plasma
C
attached to albumin
D
as bicarbonate ions
Factors Influencing Breathing Rate & Depth
1.
rising CO2 - MOST POWERFUL
2.
PO2 drops substantially
> ventral respiratory group (VRG) - generates
basic rhythmic rate of 12-15 breaths per
minute
• pontine respiratory centers (pons) influence and modify activity of VRG
A
>
causes chemoreceptors to become more
sensitive to PCO2
>
falls below 60 mm Hg reflexively increases
ventilation
3.
arterial pH drops (becomes more acidic, more H+)
>
could be rising CO2 levels or metabolic activities
like increased lactic acid during exercise
Other Controls of Respiration
emotions, pain, cold/hot
*voluntary control until CO2
reaches critical levels
protective
response to
keep lungs
from over
stretching
trigger
coughing
and
sneezing
22 The Respiratory System
...How is our breathing regulated?
7 The most important regulator of
breathing rate and depth is the
concentration of oxygen.
True
False
8 MATA: Which of the following play a role
in regulating our breathing?
A irritants
B
CO2 levels
C
blood pH
D
stretch relfex
E
VRG and DRG
F
pons
G
emotions