Transcript cont`d

Functions
Brings oxygen into the
bloodstream
Removes carbon dioxide from
the blood
Transfer of gases
Pulmonary ventilation

breathing in and out
External respiration

gas molecules diffuse between
the air sacs and the tiny
capillaries
Transfer of gases (cont’d)
Internal respiration

movement of oxygen and carbon
dioxide between the bloodstream
and body cells
Organs of the Respiratory
System
Upper
respiratory tract



Nose
Pharynx
Larynx
Organs of the Respiratory
System (cont’d)
Lower
respiratory
tract
 Trachea
 Bronchi
 Bronchioles
 Alveoli
Nose
Initial receiving
chamber for inhaled
air
Formed by 2 nasal
bones and cartilage
External nares =
nostrils
Nasal septum separates nare and
nasal cavity
Nose (cont’d)
Vestibules –
small chambers
containing hairs

Filter dust and
insects
Conchae –
turbinate bones
in nose.

Increase surface
area – air gets
warmed before it
goes to the lungs
Nose (cont’d)
Mucous membrane - warms
and moistens inhaled air and
traps particles
Olfactory receptors located in
mucosa in superior part of nasal
cavity
 Ciliated cells in mucosa – move
contaminated mucus to throat,
where swallowed and digested

Nose (cont’d)
Nasal cavity
separated from
oral cavity by
palate
Cavity surrounded
by paranasal
sinuses
Lacrimal ducts also
drain into cavity
Pharynx
A.K.A. the throat
From back of nasal
cavity to the larynx
Common passageway
for food and air
Formed by skeletal
muscle and lined
with mucous
membrane
Receives air from the
nasal cavity via
internal nares
Pharynx (cont’d)
3 Segments

Nasopharynx
 Superior part
 Receives air
from nasal
cavity
 Two auditory
tubes open
into here
Pharynx (cont’d)
3 Segments
(cont’d)


Oropharynx
 What you see
when looking
in a mirror
Laryngopharynx
 Unites with
larynx in neck
Pharynx (cont’d)
Clusters of lymphatic tissue called
tonsils found in pharynx
Larynx
A.K.A. voicebox
Connects the
pharynx with the
trachea
Provides passage to
air
Prevents solid
material from
entering the trachea
Houses the vocal
cords
Larynx (cont’d)
Walls made up of 9 pieces of
cartilage

Thyroid cartilage


“Adam’s Apple”
Cricoid cartilage
Larynx (cont’d)
Walls (cont’d)

Epiglottic cartilage (epiglottis)
Spoon-shaped flap of elastic cartilage
 Protects superior opening of larynx


3 pairs of smaller cartilages attached
to vocal cords
Larynx (cont’d)
Mucous membrane contains 2
pairs of folds
False vocal cords
 True vocal cords

Vibrations of the true vocal cords
as air rushes past produce sound
Trachea
A.K.A windpipe
Between the
larynx and the
bronchi
Supported by
incomplete rings
(C- shaped) of
cartilage
Trachea (cont’d)
Internally lined with ciliated mucous
membrane
Mucus carries particles trapped in
sticky mucus toward the pharynx
Bronchial Branches
Division of trachea
Into right and left
primary bronchi


Right – more
vertical (more likely
to be blocked)
Left – more
horizontal because
crosses over the
heart
Bronchial Branches (cont’d)
Enter the lungs,
subdivide into
smaller and smaller
branches
(secondary ,
tertiary, etc)
Smallest of
conducting
passageways are
bronchioles – no
cartilage
Bronchial Branches (cont’d)
This branching network is
called the bronchial or
respiratory tree
Bronchial Branches (cont’d)
Continue into alveolar ducts
Terminate in alveoli – air sacs

Only site of gas exchange between
external environment and bloodstream
 Occurs at respiratory membrane
(air-blood barrier)
 Via diffusion
Bronchial Branches (cont’d)
 300-500
million alveoli
 Enormous surface area
 Resemble bunches of grapes
 Each consists of microscopic air
space surrounded by thin
epithelial wall
 Interspersed cells produce
surfactant.
 Allows alveoli to inflate
Bronchial Branches (cont’d)
 Alveolar
pores connect
neighboring air sacs
 Provide alternative routes for
air to reach alveoli
 Alveoli make up bulk of lungs
 Lungs are then mostly air space
 Soft and spongy
Lungs
Consist of branches
of the bronchial
tree, alveoli, and
supportive tissue
Located in thoracic
cavity within the
rib cage
 Superior apex
located just deep
to clavicle
 Base rests on
diaphragm
Lungs (cont’d)
Serous membranes surround
each lung
Outer layer - parietal pleura
 Inner layer - visceral pleura

Pulmonary Ventilation
Provides an exchange of air between
the external environment and the
spaces within the alveoli of each lung
Sets the stage for gas exchange with
the bloodstream
2 events

inspiration and expiration
Inspiration
Initiated by the
contraction of the
respiratory muscles,
diaphragm, and
external intercostal
muscle
Cause the thoracic
cavity to expand
The pleural cavity
volume increases
and pressure
decreases
Inspiration (cont’d)
The lung surface is pulled
outward, causing the lung volume
to increase
The alveolar pressure falls below
the atmospheric
Air rushes into the alveoli
Expiration
Passive process
Relies on the
ability of the
lungs and thoracic
wall to recoil
Respiratory
muscles relax,
causing the
thoracic cavity to
return to its
original volume
Expiration (cont’d)
The thoracic cavity decreases in
size
The pleural cavity pressure
increases
The alveolar pressure becomes
greater than the atmospheric
pressure
Air flows out of the alveoli
Expiration ( cont’d)
Intrapleural
pressure is
always negative
 Major factor
preventing
collapse of
lungs
Expiration ( cont’d)
If, for any reason, this pressure
becomes equal to atmospheric
pressure, the lungs recoil
completely and collapse
(atelectasis).
Lung is useless for ventilation
Presence of air in pleural space pneumothorax
Respiratory Volume
Influences
activity
 sex
 height
 age
 weight
 state of health

Respiratory Volume
(cont’d)
Spirometer - measures respiratory
volume under different conditions &
compares with average values
Tidal volume (TV)

Normal quiet breathing moves 500 ml in
and out of the lungs each breath
Respiratory Volume
(cont’d)
Inspiratory reserve volume (IRV)

Maximum amount of air that can be
inhaled forcibly over the tidal volume
 Between 2100 and 3200 ml
Expiratory reserve volume (ERV)

Maximum amount of air that can be
exhaled forcibly over the tidal volume
 1200 ml
Respiratory Volume
(cont’d)
Residual volume (RV)
The amount of air remaining in the
lungs following a forced expiration
 1200 ml
 Important because allows gas
exchange to go on continuously even
between breaths and helps keep
alveoli open

Respiratory Volume
(cont’d)
Vital capacity (VC)
Total amount of exchangeable air
 The sum of the TV + IRV + ERV
 4800 ml

Respiratory Volume
(cont’d)
Total lung capacity
Total amount of air contained in
the fully inflated respiratory
system
 The sum of the VC + RV
 6000 ml

Respiratory Volume
(cont’d)
Dead Space Volume
Air that enters respiratory tract
and never reaches alveoli
 Of 500 ml of TV , dead space vol.
is 150 ml

External Respiration
Exchange of gases btwn the alveoli
& bloodstream
Across the thin respiratory
membrane
Always more O2 in the alveoli than
there is in the blood
Causes pressure gradient across the
resp. membrane forcing O2 from
alveoli into the O2-poor blood of
capillaries
External Respiration
(cont’d)
O2 transported in the blood in 2
ways:

98% bound to hemoglobin
(oxyhemoglobin or HbO2)


Carried thru bloodstream to the tissue
capillaries
Other 2% carried in a dissolved state
within the plasma
External Respiration
(cont’d)
Movement of O2 from alveoli into
the bloodstream accompanied by
CO2 moving in opposite direction
 More CO2 in blood than in alveoli
 Causes a pressure gradient –
moves CO2 into alveoli
Internal Respiration
Exchange of gases btwn capillaries &
body cells
Includes movement of O2 from the
capillaries to interstitial fluid and on
to cells
Includes the diffusion of CO2 from
cells into interstitial fluid on to the
capillaries
Respiratory Center
Located in the medulla & pons
Medullary respiratory centers
Inspiratory center
 Sets basic rhythm of breathing
 Ventral respiratory group
 Activated when need arises to breathe
more forcefully

Respiratory Center (cont’d)
Pons respiratory centers
Appear to smooth out the
transitions from inspiration to
expiration & vice versa
 Pneumotaxic center

Regulates the breathing rate by
inhibiting inspiration
 Prevents overinflation


Apneustic Area

Inhibits expiration
Respiratory Center (cont’d)
Eupnea
Normal respiratory rate
 12-15 respirations/minute

Factors that Affect Breathing
Chemicals

Chemosensitive area in medulla and
chemoreceptors in arteries detect
levels of O2, CO2, and H+ in the blood


Increased CO2 and decreased blood pH –
most impt stimuli leading to increased rate
and depth of breathing
Stimulate hyperventilation if CO2 levels
rise too high
Factors that Affect Breathing
(cont’d)
Stretch Receptors
Located in the walls of the lungs
 Prevent overextension of the
lungs during inspiration

Factors that Affect Breathing
(cont’d)
Mental State
Breathing & and depth - under both
voluntary & involuntary control.
 Cannot stop breathing completely using
conscious thought
 Certain emotions increase breathing
rate

Factors that Affect Breathing
(cont’d)
Physical factors
Talking, coughing, exercise
 Increased body temperature increases
rate of breathing

Chronic Obstructive
Pulmonary Diseases (COPD)
Emphysema
Alveolar walls break down and enlarge
 Lungs lose elasticity (compliance)
 Expiration becomes an active process

Chronic Bronchitis

Excessive mucus production in lower
respiratory passageways
Asthma
Constriction of bronchioles
Restrict airflow
Wheezing and shortness of breath
Tuberculosis
Infectious disease caused by
bacterium
Mainly affects lungs
Fever, weight loss, cough, spitting up
blood
Lung Cancer
1/3 of all cancer deaths in U.S.
Extremely aggressive
Metastasizes rapidly
Pneumonia
Infection of alveoli
Fluid build-up within the lungs
O2 exchange usually diminishes
If not treated, can cause death
Cystic Fibrosis
Inherited disorder
Secretion of thick and sticky mucus
and an unusual secretion of sweat
and saliva
Traps air in smaller airways
Progressive lung damage that is fatal
Can also affect digestive system
Other Disorders
Pleurisy
Hypoxia – reduced availability of
oxygen in blood – become cyanotic

CO poisoning – unique type of hypoxia
SIDS – crib death
Infant respiratory Distress Syndrome
– lack of surfactant in premature
infants – difficulty in breathing