The Respiratory Sys
(pgs 829-873)
Ventilation
– moving air
Respiration
– exchanging gases
v
Respiratory Sys
Ø
Function
§
Supply
O2 to body
§
Dispose
of CO2 from body
v
4 phases of respiration
Ø
Pulmonary
Ventilation (Breathing)
§
Moving
air into/out of lungs
Ø
External
Respiration
§
Movement
of O2 from lungs to blood
§
Movement
of CO2 from blood to lungs
§
Exchanging
gases w/ air in lungs
§
Called
“external” b/c it is soon exhaled
Ø
Transportation
of Respiratory gases
§
Transport
of O2 from lungs to tissue cells
§
Transport
of CO2 from tissue cells to lungs
§
Blood
= transport fluid
Ø
Internal
Respiration
§
Movement
of O2 from blood to tissue cells
§
Movement
of CO2 from tissue cells to blood
§
Exchange
of gases inside body
v
Respiratory/Circulatory Sys
Ø
If
either fails = O2 starvation
v
Functional Anatomy of Respiratory
Sys
Ø
Nose,
nasal cavity, pharynx, larynx, trachea, bronchi (& subdivisions), lungs
(alveoli)
Ø
2
zones
§
Respiratory
zone
·
Actual
site of gas exchange
·
Composed
of respiratory bronchioles, alveolar ducts, alveoli
§
Conducting
zone
·
Carries
air to lungs
¨
Cleanses
Ø
Mucus
= fly paper (sticky)
§
Traps
dust
¨
Humidifies/Moistens
Ø
Air
passes over mucosa
¨
Warms
Ø
B.v.
in nose vasodilate
§
↑
blood = ↑ heat of air to prevent shock to lungs
·
Doesn’t
do respiration
·
Composed
of nose, pharynx, trachea, larynx, bronchi, bronchioles
v
The Nose and Paranasal Sinuses
Ø
Functions
of Nose
§
Provides
an airway for respiration
§
Moistens
and warms entering air
§
Filters
and cleans inspired air
§
Serves
as a resonating chamber for speech
§
Houses
olfactory (smell) receptors
Ø
Structures
§
External:
external nose
·
External
openings
¨
Nostrils
(external nares)
§
Internal:
internal nasal cavity
·
Nasal
septum
¨
Cartilage
¨
Vomer
bone
¨
┴
plate ethmoid bone
·
Roof
¨
Ethmoid
& sphenoid bones
·
Floor
¨
Palate
Ø
Hard
§
Separates
nasal & oral cavities
§
Supported
by maxillary process & palatine bones
Ø
Soft
§
Muscular
·
Vestibule
¨
Chamber
above nostrils
¨
Lined
w/ skin containing sebaceous (oil) & sweat glands
Ø
Lined
w/ vibrissae (nose hairs)
§
Trap
dust & pollen
·
Mucosa
¨
Lining
on sides of nose
¨
Olfactory
mucosa
Ø
Lines
slit-like superior region of nasal cav.
Ø
Contains
smell receptors
¨
Respiratory
mucosa
Ø
Pseudostratified
ciliated columnar
§
Cilia
·
Moves
contaminated mucus to throat where it is swallowed and later digested by
stomach juices
Ø
Contains
goblet cells
§
Mucous
glands (secretes mucus) & serous glands (secretes H2O &
enzymes)
·
1
qt/day
·
Defensins
– antimicrobial
·
Lysozomes
– antibacterial
¨
Nasal
mucosa
Ø
Rich
supply of nerve endings
§
Contact
w/ dust & particles triggers sneeze reflex
·
Nasal
conchae (see diag 22.3 pg 832)
¨
Scroll
like projections of nasal wall
¨
Superior,
middle, inferior
¨
Meatus
Ø
Groove
below e@ (each) conchae
¨
Enhance
air turbulence in cavity
Ø
Allows
nongaseous particle to get trapped
¨
Functions
Ø
During
inhalation
§
Filter
§
Heat
§
Moisten
Ø
During
exhalation
§
Reclaims
heat & moisture
·
Minimizes
moisture & heat loss from body thru breathing
·
Paranasal
sinuses (spaces next to nose)
¨
Located
in frontal, sphenoid, ethmoid, maxillary bones
¨
Lined
w/ mucosa
¨
Lighten
skull
¨
Warm
& moisten air
v
The Pharynx
Ø
Connects
nasal & oral cavities
Ø
“Throat”
Ø
3
regions
§
Nasopharynx
·
Behind
nasal cavity
·
Above
soft palate
·
Air
passageway only
·
Uvula
¨
Keeps
food & liquids OUT
¨
Ciliated
pseudostratified columnar epithelium
¨
Pharyngeal
tonsil
Ø
Destroys
pathogens entering nasopharynx in air
§
Oropharynx
·
Behind
oral cavity
·
Connected
by archway called “fauces”
·
Passageway
for food/liquid & air
·
Stratified
squamous epithelium
¨
Protective,
resist abrasion
·
Palatine
tonsils
¨
Sides
of fauces
·
Lingual
tonsil
¨
Base
of tongue
§
Laryngopharynx
·
Food
& air passageway
·
Stratified
squamous epithelium
·
Behind
epiglottis
v
The Larynx
Ø
Voice
box (switching box)
Ø
3 main
functions
§
Provide
open airway
§
Switching
mechanism to route air (trachea) & food (esophagus)
§
Voice
production
Ø
Cartilage
in larynx (diag 22.4 pg 834)
§
2
arytenoid – anchors vocal cords
§
2
corniculate – looks like kernel of corn
§
2
cuneiform
§
1
thyroid
·
Laryngeal
prominence (Adam’s apple)
§
1cricoid
§
1
epiglottis (guardian of airways)
·
Mucosa-containing
taste buds
Ø
Swallowing
§
Entire
larynx up
§
Epiglottis
mushes against tongue & is forced downward at unattached end
§
Epiglottis
covers opening of trachea
§
Food/liquid
slides down epiglottis into esophagus
Ø
Vocal
ligaments
§
Attached
to arytenoid cartilage
§
Composed
of elastic fibers
§
Form
core of mucosal folds
·
Vocal folds
(true vocal cords)
¨
Strings
of CT
¨
Pearly
white (no b.v.)
¨
Vibrate
producing sounds
¨
∆
pitch = ∆ length or tension of cord
¨
↑
pitch = tighten or shorten ( musc
attached to arytenoids)
¨
Slow =
low tension = low pitch
¨
Fast =
high tension = high pitch
·
Glottis
¨
Space
between true vocal cords
Ø
Sphincter
functions of larynx
§
Valsalva’s
maneuver
·
Vocal
folds acting as sphincter that prevents air passage
¨
Prevents
exhalation during abdominal straining
Ø
Associated
w/ defecation
Ø
Associated
w/ lifting a heavy load
The Trachea
– around 4 inches long
“Windpipe” – from neck to chest,
ends at division (bronchii)
Layers
Mucosa
Goblet cells
(make mucous) - microvilli
Cilia to move mucous to pharynx
Lamina propria
- elastic
Submucosa
Connective tissue
layer
Contains Seromucous
glands – help to make mucous
Adventitia
Connective Tissue with 16-20 partial
rings of cartilage
Trachealis
muscle
Across
the posterior part of the “rings” (closes the ring)
Smooth
muscle – contracts to narrow trachea
Faster
air flow – coughing
Bronchi and
bronchial tree
Primary Bronchi – one per lung
Right is shorter, wider,
more vertical
Secondary Bronchi
One per lobe of lung
3 on right,
2 on left
Tertiary (“segmental”) Bronchi
One for each segment (segment is a
part of lobe)
“Bronchial Tree”
Keeps dividing (23 divisions)
Bronchioles (little bronchi)
Smaller than
1 mm
Terminal Bronchioles
Smaller than
½ mm
Composition of Bronchi changes as they divide
|
Structure |
Cartilage
type |
Epithelium |
Muscle |
|
Large Bronchi |
Cartilage
rings |
Psuedostratified,
ciliated Many goblet
cells for mucous |
Very
little |
|
Small
Bronchi |
Reduced rings |
Columnar (less
production/move) |
More muscle |
|
Bronchioles |
Cartilage
“plates” |
Cuboidal (very
little mucous/cilia) Macrophages
present |
Muscle ring
|
Most of bronchial tree is part of conducting zone
No gas
exchange in conducting zone
Respiratory zone
Anywhere
gas exchange happens
(anywhere
there are alveoli)
Alveoli
Little round chambers (hollow) where
gas exchange happens
Around 300 million in the lungs
May be attached directly to “respiratory
broncholes”
Named because they have
alveoli for gas exchange
May occur in clusters (“Alveolar Sac”)
Alveolar Sac – like a
bunch of grapes
Alveoli – like a grape
Cell types
Type 1
cells
Main
component of wall
Make
angiotensin converting enzyme (urinary/circulatory system)
Sit
on a basal lamina
Shared
with the capillaries
Respiratory Membrane (see pg. 841)
Type
1 | basal lamina | tunica intima
Type II cells
Less
common
Make
surfactant
Fluid
that reduces surface tension in lung (more below)
Other features of Alveoli
Alveolar
pores
Tubes
connecting adjacent alveoli
Equalize
pressure
Alternate
route
Still
use alveoli if disease blocks alveoli
Macrophages
Eat
any microbes that get inhaled
Crawl
up bronchial tree until they encounter cilia
Carried
to throat and swallowed
2
million/hour
Elastic
Fibers
Surround
alveoli (see pg. 841)
Lungs
All of thorax except mediastinum
Features
Hilus – notch where root
attaches
Root
– bronchi and vessels that attach at hilus
Apex – tip at top
Base – surface against diaphragm
Fissures – separations between
lobes
Right lung
Oblique
fissure – diagonal between middle & lower
Horizontal
fissure – between middle & upper
Left lung
Oblique
fissure
Cardiac notch
Notch in
left lung to accommodate the heart
Costal (“rib”) surface
Surface of
lung resting against ribs
Subdivisions of lung
Lobe
Bronchiopulmonary
segment
Lobe
(penny size or smaller)
Structure
Mostly air
Tissue of lungs = “stroma”
Bronchial Arteries
High pressure, systemic circuit
All of lungs
except alveoli
BLOOD DRAINS VIA
PULMONARY VEINS!!!!
Pleura
Serous
membranes
Visceral
and parietal layers
Serous
fluid between
Lubrication
Lungs stick to ribs from surface
tension of serous fluid
Breathing
Pulmonary
ventilation (moving air in and out of lungs)
Inspiration
= breath In
Expiration
= air Exits
Respiratory pressure
“Air always
flows from high pressure to low pressure”
Patm = atmospheric pressure
(~760 mm Hg / 15 lbs/square inch)
Ppul = pressure inside
alveoli (“intrapulmonary pressure” –
bad name)
If Ppul > Patm
the air flows out of lungs
If Ppul < Patm
the air flows into lungs
Intrapleural pressure
pressure of serous fluid between
pleura layers
Should
ALWAYS be negative (below Ppul & Patm )
Usually
–4 mm Hg
Why
surface of lungs are stuck to ribs
If
positive, the lung will collapse
Pneumothorax
McSwain
Dart or Chest Tube
Causes
Elasticity
of alveolar wall
Surface
tension of alveolar fluid
Boyle’s
Law: if amount is constant and pressure goes up
The
volume will go down
Quiet (tidal)
Diaphram – drops
External Intercostals – pull ribs up
and out
Deep (inspiratory reserve)
Diaphram – drops
External Intercostals – pull ribs up
and out
Sternocleidomastoid – pull ribs up and
out
Pectoralis minor – pull ribs up and out
Why
Muscle movement causes lung volume to
increase
Ppul drops
Air rushes
in to compensate
Expiration
Quiet (tidal)
Muscles relax
lungs return to normal size
elastic
surface tension
Deep (expiratory reserve)
Abdominal muscles (oblique and
transverse)
Push organs up against diaphragm
Internal intercostals
Pull ribs inward
Why
Lungs volume reduced
Ppul rises
Air leaves
lungs to compensate
F = delta P / R (just like blood)
Surfactant (type II cells)
lowers surface tension
Water surface tension is so strong it would collapse
lungs
Lung compliance
How stretchy the lungs are
Healthy lungs are very compliant
(stretchy)
Very
little effort to stretch them and breath
Respiratory volumes
Tidal volumes (TV) – the amount you normally breath in
and out at rest
(half a liter) KNOW THIS
Reserve volumes – the extra space in your lungs that
could be used
Inspiratory reserve volume (IRV) – the extra
you could breath in
Expiratory reserve volume (ERV) – the extra
you could breath out
Residual volume (RV) – the amount you never get out of
lungs (residue)
MATH WARNING: PAY ATTENTION TO THIS!!! (PG 849-851)
Respiratory Capacities
Inspiratory Capacity – amount you can breath in after TIDAL
exhale
Normal amount you breath in + Extra you
could
IC = TV + IRV
Functional Residual Capacity –
amount left in lungs after TIDAL exhale
Amount you still
could breath out + amount you’ll never get out
FRC = ERV + RV
Vital Capacity = amount of air
you could breath out after breathing in as much as possible
Normal amount in +
extra in + extra you can breath out
VC = TV + IRV +
ERV
Total Lung Capacity = all the air
that can be in the lungs
TLC = TV + IRV +
ERV + RV
What partial pressure is
% of total air
pressure due to a gas
Nitrogen
= 79%
Oxygen
= 21%
Carbon
Dioxide = 0.04 %
“When a mixture of gases is in contact
with a liquid,
IF ALL GASES
HAVE THE SAME SOLUBILITY,
each gas will dissolve in the liquid in proportion to
its partial pressure.”
Do all gasses have the same solubility? NO
Carbon Dioxide =
very soluble
Oxygen = not so
soluble (1/20th of carbon dioxide’s solubility)
Nitrogen = almost
no solubility in fluids (more soluble in fats)
We exchange about the same amount
of oxygen and carbon dioxide
Oxygen
Low
solubility
Still
dissolve a lot because it has fairly high partial pressure
We
can breath :)
Carbon Dioxide
Very
little in air (low partial pressure)
Very
soluble
Still
dissolve as easily as oxygen
Nitrogen
Almost
insoluble
Doesn’t
go into blood unless it is at very high pressure
Scuba
More
soluble in fats
Nitrogen
narcosis
Won’t
go into blood easily when leaving body
Bends
Pg.
855
Ventilation
perfusion coupling
Low oxygen area of lungs (e.g. disease)
Bronchioles
constrict – less air to bad area
Arterioles constrict
– less blood to bad area
High oxygen area of lungs
Broncholes relax –
more air to that area
Arterioles relax –
more blood to that area
Result – we send air and blood to
the parts of the lungs
That are best able
to do gas exchange. We ignore
The parts that can’t
do their job well
P.
856
Internal
respiration
Exchange of gases at body tissues
Depends on pressure gradients
just like at lungs
Oxygen
transport
Dissolved in blood (1.5%)
On RBC (98.5%)
Hemoglobin
4
globins, 4 hemes
carries
4 O2 molecules
Oxygen Affinity
The more oxygen,
the more affinity for oxygen
No oxygen “might be nice to
have”
One oxygen “that’s good, let’s
have another”
Two oxygen “wow, this is really
good stuff,
I
need to keep some of it around”
Three oxygens “This is a stickup. Give me a fourth oxygen”
Things that lower
hemoglobin’s affinity for oxygen
High
temperature
Acidic
conditions
Lots
of CO2 in the area
Hyperventilation
“Saturated” = full
Artery
Full of oxygen
(98% saturated)
Vein
Less oxygen( 75%
saturated)
Still more than
half full
Hyperventilating
Breathing deeper and harder
VERY LITTLE EFFECT ON OXYGEN
Already 98% full,
can’t add much more
BIG EFFECT ON CARBON DIOXIDE
Breathing faster
removes CO2 from blood
Can remove so much CO2 that you
can black out before
Needing to breath (pg. 865)
P.
859
Hypoxia
– low oxygen to tissues
Causes
Anemic Hypoxia – few RBC or
little Hb to carry Oxygen
Ischemic hypoxia – blood doesn’t
flow well, can’t deliver oxygen
Histotoxic hypoxia – cells can’t
take oxygen to use (cyanide)
Hypoxemic hypoxia – low oxygen
levels
p.
859
CO2
Transport (3 ways)
As a gas dissolved in plasma
(7-10%)
Bound to hemoglobin (20%)
As bicarbonate ions (70%)
KNOW THIS!!!
CO2 + H20 <==> H2CO3
<==> H+ + HCO3-
Carbon Dioxide + Water <==> Carbonic Acid
<==> Hydrogen Ions + Bicarbonate
This
happens inside red blood cells
Hydrogen
ions bind to hemoglobin, bicarbonate ions go into blood plasma
Pg.
861
“Acid”
= more H+ ions than OH- ions
“Base”
= more OH- ions than H+ ions
Bicarbonate
Ions are one type of blood buffer
If
the blood is too acidic (has too many H+ ions) they will bind with bicarbonate
If
blood is too basic, the carbonic acid will break down to release H+ ions
Control
of Respiration
Medulla: (2 centers)
Dorsal Respiratory
Group (inspiratory center)
Pacemaker
for breathing
Controls
diaphragm and external intercostals
(stuff that causes
inspiration)
Ventral
Respiratory Group
Controls
internal intercostals, abdominals
(stuff
that causes forced exhalation)
Controls
sternocleidomastoid
(forced
inhalation)
Hypothalamus
Emotions
that affect breathing
Factors affecting breathing (pg. 864)
Pulmonary
irritation – vagal afferent nerves
Fumes
– constrict broncholes
Sneeze
– expel irritant
Chemical factors
“Of all the
chemicals influencing respiration, CO2 is the most potent and
the most closely
controlled”
CO2 levels up =
need to breath
Chemoreceptors
in medulla
Sensors
in carotid sinus and aortic arch
Influence of pH
(pg. 866)
Too
Acid = breath faster/deeper = less CO2 in blood = less carbonic acid
Too
basic = breath slow/shallow = more CO2 = more carbonic acid
READ
“A CLOSER LOOK”, pg. 866