The Respiratory System
Introduction
 Functions







Obtain oxygen
Remove carbon dioxide
Trap particles from air
Control temperature and water content of
air
Produce vocal sounds
Help with sense of smell
Regulate pH of blood
Organs
of the
Respiratory
System
Respiration

The process of gas exchange between the
atmosphere and cells
 Ventilation


External Respiration


gas exchange between blood and air in lungs
Gas Transport


move air into and out of lungs (breathing)
from blood to lungs and body cells
Internal Respiration

exchange between blood and body cells
Organs of the Respiratory
System
 Upper




Nose
Nasal Cavity
Paranasal Sinuses
Pharynx
 Lower




Respiratory Tract
Respiratory Tract
Larynx
Trachea
Bronchial Tree
Lungs
Organs and
Structures
of the
Respiratory
System
Nose
 Supported
internally by bone and cartilage
 Nostrils


openings for air to enter and exit
guarded by internal hairs
• keeps large particles out
Nasal Cavity
 Hollow
space behind nose
 Nasal Septum

divides cavity into right and left
 Nasal


Conchae
bones that divide cavity into passageways
supports mucous membrane
Mucous Membrane
 Contains
cells that secrete mucus
 Contains a lot of blood vessels


when air passes, heat leaves blood and
warms air to body temp
moistens incoming air
 Traps
dust and small particles trying to get
in


particles move to pharynx and are swallowed
destroyed by gastric juices
Mucous Membrane
FYI - Anthrax
 Too
small to get trapped by cilia
 Coat spores with “bioweapon”
 Reaches lungs
 Releases toxins and then you die
Check Your Recall
 What
is respiration?
 Which organs constitute the respiratory
system?
 What are the functions of the mucous
membrane that lines the nasal cavity?
Paranasal Sinuses
 Air-filled
spaces in maxillary, frontal,
ethmoid and sphenoid bones
 Continuous with mucous membranes of
the nasal cavity
 Function


reduce weight of skull
resonant chambers affecting quality of voice
Pharynx
 Throat
 Passageway
for food and air
 Helps produce sound for speech
Larynx
 Enlargement
of airway at top of trachea
 Functions



moves air in and out of trachea
keeps foreign objects out of trachea
houses vocal cords
Larynx Structure
 framework
of muscles
and cartilages bound
by elastic tissue
 cartilages



thyroid (Adam’s Apple)
cricoid
epiglottic
Larynx Structure-Vocal Cords
 False



upper folds
don’t produce sound
close airway during
swallowing
 True


vibrate side-to-side to generate sound waves
sound waves made into words by changing
shape of pharynx and oral cavity and using
tongue and lips
Larynx Structure-Vocal Cords
 Glottis


opening between vocal cords during normal
breathing
closes when food or liquid is swallowed
 Epiglottis


flap that covers opening into larynx
also keeps food and water out of airway
Everyday Life
 Laryngitis






when you lose your voice
mucous membrane of larynx is inflamed
caused by infection or irritation from
something you inhaled
prevents vocal cords from vibrating freely
usually no big deal-only bad if they are so
swollen the airway is obstructed
if this happens then you need a breathing
tube
Check Your Recall
 Describe
the structure of the larynx.
 How do the vocal cords produce sounds?
 What is the function of the glottis?
 What is the function of the epiglottis?
Trachea
 Windpipe
 Flexible



tube
2.5cm wide
12.5cm long
lined with mucous membrane cells
 Transports
air between the larynx and
bronchi
 Made of C-shaped cartilage rings


cartilage helps keep shape
smooth muscle allows expansion when food
goes down the esophagus
Bronchial Tree

Branched airways going from trachea to air sacs
in lungs
 Order









Primary bronchi
Secondary bronchi
Tertiary bronchi
Bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli
Bronchial
Tree
Gas Exchange
 Oxygen
diffuses from
air inside
alveolus into
the capillary,
while carbon
dioxide
diffuses from
blood in the
capillary into
the alveolus.
Check Your Recall
 What
is the function of the cartilaginous
rings in the tracheal wall?
 Describe the bronchial tree.
 Explain how gases are exchanged in the
alveoli.
Lungs
 Soft,
spongy, cone-shaped
 Right and left separated by mediastinum
 Enclosed by diaphragm and thoracic cage
 Takes up most of thoracic cavity
 Held in place by bronchus and blood
vessels
 Right is larger – 3 lobes
 Left only has 2
Lungs continued
 Visceral


layer of serous membrane attached to each
lung surface
folds back to become…
 Parietal


pleura
forms part of the mediastinum and lines inner
wall of thoracic cavity
 Pleural

pleura
cavity
potential space between visceral and parietal
contains fluid so surfaces can move past each
other without friction when you breathe
Lungs continued
Breathing Mechanism-Inspiration
 Atmospheric
pressure is 760mm
 Volume and Pressure are inversely related


Higher volume means lower pressure
Lower volume means higher pressure
Breathing Mechanism-Inspiration
 Impulse
carried on phrenic nerve
 Stimulates diaphragm to contract
 Thoracic cavity enlarges
 Air pressure inside lungs drop
 Air is forced in
 Also: External intercostal muscles
between ribs contract


This raises ribs and elevates sternum
Enlarges thoracic cavity even more
Breathing Mechanism-Inspiration
Possible Problem
 Lung
expansion depends on pleural
membranes
 You want these membranes to stick
together

like cover slip on microscope slide
 Alveoli
are so small they get stuck
together and air can’t get in

Surfactant – mixture of lipids and proteins
secreted in alveolar spaces helps keep them
from collapsing
Everyday Life Connection
 Newborn
uses 20X as much energy for the
first breath compared to the rest.

Because alveoli are only partially inflated
 Preemies



Don’t produce enough surfactant to keep
alveoli from collapsing
Often get Respiratory Distress Syndrome
Put on ventilator and receive synthetic
surfactant through endotrachael tube
Breathing Mechanism-Expiration
 When
muscles relax elastic recoil causes
lung and thoracic cage to return to original
shape
 Alveoli decrease in size so pressure
increases
 Pressure inside is now more than outside
so air moves out
Real World
 Not
normal to have actual space in pleural
cavity
 Puncture in thoracic wall might allow air in
from outside

pneumothorax
 Air
moving in this space from outside
causes lung to collapse

atelectasis
Nonrespiratory Movements
 Movements
in addition to breathing
 Clear air passages

sneezing or coughing
 Express

emotion
laughing or crying
 Usually
result from reflexes
Nonrespiratory Movements
 Coughing





– clears lower respiratory tract
Take in deep breath
Glottis closes
Force air upward against closure
Glottis opens suddenly
Blast of air removes substance
Nonrespiratory Movements
 Sneezing




– clears upper respiratory tract
Initiated by mild irritation in lining of nasal
cavity
Blast of air forced up through glottis
Uvula is depressed so opening to oral cavity
is closed
Can move particles out at 200mph
Nonrespiratory Movements
 Laughing

take in a breath and release in a series of
short expirations
 Crying

similar movements
 This
is why it is sometimes hard to tell if
someone is laughing or crying
Nonrespiratory Movements
 Hiccup



Sudden inspiration due to contraction of
diaphragm while glottis is closed
Noise is air striking vocal cords
Function of hiccups still unknown
 Yawning



Sometimes you need a deep breath
Not all alveoli are ventilated during normal
breathing and blood can pass through lungs
without getting much oxygen
Low oxygen concentration triggers yawn
reflex
Check Your Recall
 Describe
the events in inspiration.
 How does expansion of the chest wall
expand the lungs during inspiration?
 What forces cause normal expiration?
Air Volumes
 Spirometry

measure of volume of air going in and out of
our lungs
 Respiratory

one inspiration plus the following expiration
 Tidal


Cycle
Volume
amount of air that enters (or leaves) during a
single cycle
Resting tidal volume is about 500mL
Air Volumes

Inspiratory Reserve Volume




Expiratory Reserve Volume




during forced inspiration (deep breath)
extra volume that enters
complemental air (3000mL)
forced expiration
supplemental air
up to 1100 mL beyond resting tidal volume
Residual Volume


1200mL
no matter how hard you try something is always left in
the lung after you breathe out
Respiratory Capacities
 Combination
of two or more air volumes
 Vital Capacity



inspiratory res. + tidal volume +expiratory res.
3000mL + 500mL + 1100mL
maximum amount person can exhale after
taking the deepest possible breath
Respiratory Capacities
 Inspiratory



tidal volume + inspiratory reserve volume
500mL + 3000mL
maximum person can inhale following a
resting expiration
 Functional



Capacity
Residual Capacity
Expiratory res. vol. + residual volume
1100mL + 1200mL
amount left in lungs after resting expiration
Respiratory Capacities
 Total


Lung Capacity
5800mL
depends on age, sex, and body size
 Anatomic


dead space
trachea, bronchi and bronchioles
gas not exchanged here-
Respiratory Volumes and
Capacities
Check Your Recall
 What
is tidal volume?
 Distinguish between expiratory and
expiratory reserve volumes.
 How is vital capacity determined?
 How is total lung capacity calculated?
Control of Breathing
 Even
though breathing is involuntary and
continues when you are unconscious the
muscles are still under voluntary control.
 Respiratory Center

groups of neurons in brainstem which control
inspiration and expiration
Control of Breathing
 Medullary

Rhythmicity Area
Dorsal Respiratory Group
• controls rhythm of inspiration
• send bursts of impulses to contract diaphragm and
other respiratory muscles
• begin weak and strengthen for two seconds

Ventral Respiratory Group
• generate impulses when forceful breathing needed
Control of Breathing
 Pneumotaxic




area
located in pons
inhibit bursts from dorsal respiratory group
control breathing rate
if this inhibition is strong your breathing rate
increases
Medullary Rhythmicity and
Pneumotaxic Areas of Control
Check Your Recall
 Where
is the respiratory center?
 Describe how the respiratory center
maintains a normal breathing pattern.
 Explain how the breathing pattern may
change.
Factors Affecting Breathing
 Chemical


CO2 levels – if high – breathing rate increases
Oxygen levels don’t normally play a role
 Degree


in body fluids
of stretch in lung tissues
inflation reflex warns if tissues stretch too
much
prevents over-inflation of lungs
 Emotional

state
fear and pain increase rate
Everyday Life

Holding your breath



changes blood concentration of carbon dioxide,
hydrogen and oxygen
these changes stimulate the control center and cause
an overwhelming urge to inhale
Hyperventilation




breathing rapidly and deeply before trying to hold your
breath
lowers carbon dioxide level
takes longer for body to get urge to inhale
can hold breath for longer period of time
Check Your Recall
 Which
chemical factors affect breathing?
 Describe the inflation reflex.
 How does hyperventilation decrease the
respiratory rate?
Alveolar Gas Exchange
 Exchange
of gases between air and blood
 Alveoli


microscopic air sacs at distal ends of alveolar
ducts
each alveolus is a tiny space within a thin wall
 Respiratory


Membrane
made of alveolar and capillary walls
exchange occurs across this membrane
Alveolar Gas Exchange
Diffusion Across Respiratory
Membrane
 Gases
diffuse from areas of higher partial
pressure to areas of lower partial pressure
 Oxygen diffuses from alveolar air into
blood and carbon dioxide diffuses from
blood in alveolar air
Everyday Life

Factors affecting diffusion




surface area, distance, solubility of gases and steep
pressure differences
Pneumonia – harms respiratory membrane
Emphysema – reduces surface area for diffusion
Membrane really thin – other chemicals besides
carbon dioxide also come out



alcohol - DWI
acetone – diabetes mellitus
can also detect kidney failure, liver disease and
digestive disturbances
Check Your Recall
 Describe
the structure of the respiratory
membrane.
 What force moves oxygen and carbon
dioxide across the respiratory membrane?
Oxygen Transport
 98%
of oxygen from lungs binds to
hemoglobin in red blood cells


known as oxyhemoglobin – released where
concentrations of oxygen are low
the rest dissolves in plasma
 Release



rate
higher if carbon dioxide concentration is high
higher if blood is acidic
higher if blood temperature is high
Oxygen Transport-Hypoxia

Deficiency of oxygen reaching tissues
 Hypoxemia


Anemic Hypoxia


diminished ability of blood to transport oxygen
Ischemic Hypoxia


decreased arterial pressure
inadequate blood flow
Histotoxic Hypoxia


defect at cellular level
cyanide poisoning
Oxygen Transport
Check Your Recall
 How
is oxygen transported from the lungs
to cells?
 What stimulates blood to release oxygen
to tissues?
Carbon Dioxide Transport
 Transported


in three forms
In solution – plasma – 7%
Bound to hemoglobin – carbaminohemoglobin
- 23%
• bonds at different site than oxygen so there is no
competition

Bicarbonate ion – 70% - reacts with water to
form carbonic acid
Carbon Dioxide Transport
Check Your Recall
 Describe
three forms in which blood can
transport carbon dioxide from cells to the
lungs.
 How can hemoglobin carry oxygen and
carbon dioxide at the same time?
 How is carbon dioxide released from blood
into the lungs?