Transcript Respiratory System

Respiratory System
Anatomy & Physiology
Chapter 14
I. Overview
A. Function:
 Brings about
the exchange
of oxygen and
carbon dioxide
between the
blood, the air,
and tissues
B. Organs
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Lungs – alveoli
C. Respiratory tract
 Pathway of air from
nose to lungs
 Air in the respiratory
tract are:
– Cleansed – by hairs,
cilia, and mucus
– Warmed – by heat
from the blood
vessels
– Moistened – by the
wet surfaces in the
passageway

Necessary to keep
lung tissue healthy
II. Structure
A. Upper Respiratory Tract
– Nasal cavities, pharynx, glottis, larynx
1. Nasal Cavity
Description: Hollow canals separated by a
septum of bone and cartilage
 Function: Filter, warm, and moisten the air


Paranasal Sinuses – Cavities within bones
surrounding the nasal cavity
– Function of the sinuses
 Lighten
the skull
 Act as resonance chambers for speech
 Produce mucus that drains into the nasal cavity

Mucous membrane lines nasal cavity
– Cilia moves mucous and trapped particles to
the pharynx

Contains lateral projections called conchae
– Increases surface area
– Increases air turbulence within the nasal cavity

The nasal cavity is separated from the oral
cavity by the palate
– Anterior hard palate (bone)
– Posterior soft palate (muscle)
Hard Palate
Soft
Palate
2. Pharynx – Throat
 Description:
funnel-shaped
passageway
between the
nasal cavity
and larynx
 Function:
Connects nasal
and oral
cavities to the
larynx

Three regions of the
pharynx
– Nasopharynx – superior
region, passageway for air
– Oropharynx – where oral
cavity joins pharynx,
passageway for food and
air
– Laryngopharynx – inferior
region that opens to
larynx

Tonsils – located in
oropharynx
– A lymphatic tissue that
protects against inhaled
pathogens
3. Epiglottis
Description: flap
of tissue that sits
at the base of the
tongue
 Function:
prevents food
from entering the
trachea, or
windpipe, during
swallowing

4. Larynx
Description: Also called
the voice box, contains
the vocal cords
 Function: Produces
sound
 Vocal cords are elastic
tissues that vibrate
producing sound as air
travels through

– The opening or slit in the
vocal cords is called the
glottis
B. Lower Respiratory Tract
– Trachea, bronchi, bronchioles, lungs,
alveoli
1. Trachea
 Description:
known as the
windpipe, flexible
tube that
connects larynx to
bronchi
 Function: directs
air to bronchi
 Held
open by C-shaped hyaline
cartilage
 Trachea is lined with pseudostratified
ciliated columnar epithelial cells
– Cilia sweeps mucus loaded with dust and
other debris away from lungs
Cilia
Goblet
cells
Pseudostratified
epithelial
Basement
membrane
Review
Breakdown the words “pseudostratified
ciliated columnar epithelial” to understand
the meaning.
 “pseudo” – fake
 “stratified” – layers
 “ciliated” – with hair like projections
 “columnar” – cells that are taller than wider

2. Bronchi
 Description:
Left
and right
branched tubes of
the trachea
 Function:
passageway of air
to lungs
 Bronchi
enters the
right and left lungs
– Bronchi subdivide into
smaller and smaller
branches called
bronchioles
 Right
bronchus is
wider, shorter,
and straighter than
left
3. Bronchioles
 Description:
Smallest
branches of the
bronchi
 Function:
Bronchioles
lead to the
alveoli
 Description:
4. Lungs
paired, coneshaped organ
that occupy the
thoracic cavity
 Function:
contains
alveolus where
gas exchange
occurs
 Apex
(superior
portion) is near
the clavicle
 Base (inferior
portion) rests on
the diaphragm
 Each lung is
divided into lobes
by fissures
– Left lung – two
lobes
– Right lung – three
lobes
 Coverings
of the lungs
– Visceral pleura covers the lung
– Parietal pleura lines the walls of the
thoracic cavity
– Pleural fluid fills the area between layers
of pleura to allow gliding
5. Alveoli
 Description:
Structure made up
of simple squamous
epithelium
surrounded by
blood capillaries
 Function: Exchange
of gas
 Respiratory
membrane – extremely
thin membrane that aids in the rapid
exchange of gases
 Gas
crosses the respiratory
membrane by diffusion
– Oxygen enters the blood
– Carbon dioxide enters the alveoli
 Macrophages
add protection
 Surfactant in alveoli prevents the
lung from closing or collapsing
Review
 What
gases are exchanged in the
respiratory membrane?
 How
are gases moved or transported
across the membrane?
Summary
 Draw
a flow map showing the
pathway air travels through the
respiratory system starting with the
nasal cavity and ending with the
alveoli. Underneath each structure
(8 total), write down the function.
 Ex.
III. Mechanism of Breathing
 Ventilation
– manner in which air
enters and exits the lungs
 Two phases
– Inspiration – flow of air into lung
– Expiration – air leaving lung
A. Inspiration
 Active
phase of ventilation
 Diaphragm and intercostal muscles
contract
 The size of the thoracic cavity
increases
 External air is pulled into the lungs
due to an increase in intrapulmonary
volume
B. Expiration
 Largely
a passive process which
depends on natural lung elasticity
 Diaphragm and intercostal muscles
relax
 As muscles relax, air is pushed out of
the lungs
 Forced expiration can occur mostly
by contracting internal intercostal
muscles to depress the rib cage
C. Nonrespiratory Air Movements
 Can
be caused by reflexes or
voluntary actions
 Examples
– Cough and sneeze – clears lungs of
debris
– Laughing
– Crying
– Yawn
– Hiccup
D. Ventilation Control
 Normal
breathing rate is 12-20
ventilation per minute
 Controlled by the respiratory center
in the medulla oblongata (brain)
 Factors that influence ventilation
– Nervous input
– Chemical input
 1.
Nervous input
– Intercostal and
phrenic nerve
stimulate muscles
to contract for
inspiration
– Lack of
stimulation
results in
expiration
 2.
Chemical input
– Level of carbon dioxide in the blood is
the main regulatory chemical for
respiration
– Increased carbon dioxide increases
respiration
E. Respiratory Volumes
 Normal
breathing moves about 500
ml of air with each breath (Tidal
Volume [TV])
 Many factors that affect respiratory
capacity
– A person’s size
– Sex
– Age
– Physical condition
 Inspiratory
reserve volume (IRV)
– Amount of air that can be taken in
forcibly over the tidal volume
– Usually between 2100 and 3200 ml
 Expiratory
reserve volume (ERV)
– Amount of air that can be forcibly
exhaled
– Approximately 1200 ml

Residual volume
– Air remaining in lung after expiration
– About 1200 ml

Vital capacity
– The total amount of exchangeable air
– Vital capacity = TV + IRV + ERV

Dead space volume
– Air that remains in conducting zone and never
reaches alveoli
– About 150 ml
 Functional
volume
– Air that actually reaches the respiratory
zone
– Usually about 350 ml
 Respiratory
capacities are measured
with a spirometer
IV. Gas Exchange and Transport
 Respiration
–
process of
exchanging gases
between the
atmosphere and
body cells
A. External Respiration
Exchange of gases
between air and blood
in the lungs
 Blood entering the
lungs is oxygen-poor
and carbon dioxide-rich
 Oxygen movement into
the blood

– The alveoli always has
more oxygen than the
blood
– Oxygen moves by
diffusion from an area of
high concentration to an
area of low concentration

Carbon dioxide
movement out of the
blood
– Blood returning from
tissues has higher
concentrations of carbon
dioxide than air in the
alveoli
– Pulmonary capillary
blood gives up carbon
dioxide

Blood leaving the lungs
is oxygen-rich and
carbon dioxide-poor
B. Internal Respiration
 Exchange
of gases
between blood and
body cells
 An opposite
reaction to what
occurs in the lungs
– Carbon dioxide
diffuses out of
tissue to blood
– Oxygen diffuses
from blood into
tissue
C. Gas Transport
 Oxygen
transport in the blood
– Inside red blood cells attached to
hemoglobin (oxyhemoglobin [HbO2])
– A small amount is dissolved in the
plasma
 Carbon
dioxide transport in the blood
– Most is transported in the plasma as
bicarbonate ion (HCO3–)
– A small amount is carried inside red
blood cells on hemoglobin, but at
different binding sites than those of
oxygen
V. Respiratory Disorders

A. Tonsillitis – occurs
when tonsils become
inflamed and enlarged
– Can make breathing difficult
– Tonsils are the first line of
defense against pathogens
that enter the pharynx

B. Laryngitis – infection of
larynx
– Lead to inability to talk
audibly
– Disappears with treatment

C. Chronic Obstructive Pulmonary Disease
(COPD)
– Major causes of death and disability in the
United States
– Example: chronic bronchitis, emphysema,
asthma

1. Chronic Bronchitis
– Airway becomes inflamed and fills with mucus
– Loss of cilia and normal cleansing action
– Caused by smoking cigars, cigarettes, and
some pollutants
 2.
Emphysema
– Chronic and
incurable disorder
where the alveoli
bursts and fuse into
larger air spaces
– Reduces surface
area for gas
exchange
– Caused by prolong
cigarette smoking

3. Asthma
– Disease of the bronchi and bronchioles marked
by wheezing and breathlessness
– Airways are sensitive to irritants (pollen,
animal dander, dust, etc)
– Causes muscle in the bronchioles to spasm and
may even cause them to become inflamed
– Treated with inhalers that stop the spasms or
reduce the inflammation
D. Lung Cancer
 Caused
by smoking cigarettes &
second hand smoke
 Lung cancer begins with the
thickening and callusing of the
bronchi
 Cilia is destroyed
 Atypical cells appear in tissue
 Tumor forms
 Cells break loose and spread to other
organs (metastasis)
 Tumor
can grow until it blocks
bronchi, cutting off air supply
 Lung collapses
 Treatments:
– Pneumonectomy – remove a lobe or a
whole lung
– Chemotherapy
– Radiation