Transcript Respiratory PPT.ppt

Respiratory System
The respiratory system includes tubes that
remove particles from incoming air and
transports air to and from the lungs and
the air sacs where gases are exchanged.
Respiration is the entire process of gas
exchange between the atmosphere and
body cells.
Anatomy of the Respiratory
System
The Upper Respiratory Tract
Organs of the Respiratory System
Outside the Thorax
Nose
1. Bone and cartilage support the nose
2. The nostrils are opening for air.
3. Many internal hairs guard the nostrils, preventing
entry of large particles carried in the air
Nasal Cavity
1. Nasal conchae divide the nasal cavity into
passageways and help increase the surface area of
the mucous membrane.
2. The mucous membrane filters, warms, and
moistens incoming air.
3. Ciliary action carries particles trapped in mucus to
the pharynx, where they are swallowed.
Paranasal Sinuses
1. The paranasal sinuses are spaces in the
bone of the skull that open into the nasal
cavity.
2. Mucous membrane lines the sinuses
Anatomy of the Respiratory
System
• the pharynx
– tonsils
• the larynx
– epiglottis
• the trachea
– C rings
Pharynx
1. The pharynx is behind the oral cavity and between the
nasal cavity and the larynx.
2. It is a passageway for air and food.
Larynx
1. The larynx conducts air and helps prevent foreign
objects from entering the trachea.
2. It is composed of muscles and cartilages and is lined
with mucous membrane.
3. It contains the vocal cords, which vibrate from side to
side and produce sounds when air passes between
them.
4. The glottis and epiglottis help prevent foods and liquids
from entering the trachea.
Organs of the Respiratory System
Inside the Thorax
Trachea
1. Extends into the thoracic cavity in front of the
esophagus.
2. Divides into right and left bronchi.
Bronchial Tree
1. The bronchial tree consists of branched air passages
(primary bronchi, bronchioles, and alveolar ducts) that
lead from the trachea to the air sacs.
2. Alveoli are at the distal ends of the narrowest tubes,
the alveolar ducts.
Alveoli
1. Alveoli provide a large surface area of thin simple
squamous epithelial cells through which gases can
easily be exchanged.
2. Oxygen diffuses through alveolar walls and enters
blood in the nearby capillaries, and carbon dioxide
diffuses from blood through the walls and enters
alveoli.
3. An adult lung has about 300 million alveoli, providing a
total surface area half the size of a tennis court.
Lungs
1. The mediastinum separates the left and right lungs,
and the diaphragm and thoracic cage enclose them.
2. The visceral pleura attaches to the surface of the
lungs. The parietal pleura lines the thoracic cavity.
3. Each lobe of the lungs is composed of alveoli, blood
vessels, and supporting tissue.
Review and Assessment
Match these words with 1–4 below:
surfactant, apex, epiglottis, conchae.
1. lungs
2. larynx
3. nasal cavity
4. alveoli
Chapter 9: The Respiratory System
Lesson 9.2
Respiration: Mechanics
and Control
Respiration
• also known as breathing
• air always moves from a higher pressure
area to a lower pressure area
• four key tasks involved in respiration
– pulmonary ventilation
– external respiration
– respiratory gas transport
– internal respiration
Breathing Mechanism
Changes in the size of the thoracic cavity accompany
inspiration and expiration.
Inspiration
1. Atmospheric pressure due to the weight of air is the
force that moves air into the lungs. Normal air pressure
is equal to 760mm of mercury (Hg).
2. If the pressure inside the lungs and alveoli decreases,
atmospheric pressure will push outside air into the
airways.
3. Impulses carried on the phrenic nerves stimulate
muscle fibers in the dome-shaped diaphragm below
the lungs to contract, moving it downward. The
thoracic cavity enlarges, and the pressure within the
alveoli falls to about 2mm Hg below that of
atmospheric pressure
4. The external (inspiratory) intercostal
muscles between the ribs may be
stimulated to contract, raising the ribs and
elevating the sternum, enlarging the
thoracic cavity even more, resulting in
further reduction of pressure.
5. The water molecules in the serous fluid
greatly attract one another, creating a
force called surface tension that holds
the moist surfaces of the pleural
membranes tightly together. When the
intercostal muscles move the thoracic wall
upward and outward, the parietal pleura
moves, the visceral pleura follows it,
helping to expand the lungs in all
directions
6. Certain
alveolar cells synthesize a mixture
of lipoproteins called surfactant, which is
secreted continuously into alveolar air
spaces, reducing surface tension and
decreasing alveoli’s tendency to collapse
when lung volume is low.
7. Additional muscle, such as the pectoralis
minors and sternocleidomastoids, can also
pull the thoracic cage farther upward and
outward, enlarging the cavity and
decreasing internal pressure.
Respiration
• Boyle’s law
– as the volume of a gas increases, the pressure
of the gas decreases
Respiration
• inspiration (inhalation)
– diaphragm and intercostal muscles contract
– thoracic cavity expands
• expiration (exhalation)
– diaphragm and intercostal muscles relax
– thoracic cavity shrinks
Exhalation
1. The forces responsible for normal expiration come
from the elastic recoil of tissues and from surface
tension.
2. Similarly, the abdominal organs spring back into their
previous shapes, pushing the diaphragm upward.
3. At the same time, the surface tension that develops
between the moist surfaces of the alveolar linings
decreases the diameter of the alveoli.
4. Each of these factors increases aveolar pressure
about 1mm HG above atmospheric pressure, so the air
inside the lungs is forced out through respiratory
passages.
5. If a person needs to exhale more air than normal, the
posterior internal (expiratory) intercostal muscles
can be contracted to pull the ribs and sternum
downward and inward, increasing the pressure in the
lungs. Also, the abdominal wall muscles can squeeze
the abdominal organs inward, which will increase
pressure in the abdominal cavity and force the
diaphragm still higher against the lungs
Nonrespiratory Air Maneuvers
Respiratory Air Volumes and Capacities
1. The amount of air that enters the lungs during
inspiration (about 500mL at rest) is
approximately the same amount that leaves
during normal expiration. One inspiration
followed by an expiration is called a
respiratory cycle.
2. The volume of air that enters (or leaves) during
a single respiratory cycle is termed tidal
volume.
3. During forced inspiration, air in addition to the
resting tidal volume enters the lungs. This
extra volume is inspiratory reserve volume,
and at maximum, it equals about 3,000mL.
4. During forced expiration, the lungs can expel up
to 1,100mL of air beyond the resting tidal
volume. This quantity is called expiratory
reserve volume.
5. Even after the most forceful expiration, about
1,200mL of air remains in the lungs. This is
called the residual volume.
6. Residual air remains in the lungs at all time.
This prevents oxygen and carbon dioxide
concentrations in the lungs from fluctuating
greatly with each breath.
7. Combining 2 or more of the respiratory volumes
yields four respiratory capacities.
a. vital capacity (4,600mL) – IRV +TV+ERV;
the maximum amount of air a person can
exhale after taking the deepest breath
possible
b. inspiratory capacity (3,500mL) – TV+IRV;
maximum amount of air a person can inhale
following a resting expiration
c. functional residual capacity (2,300mL) –
ERV+RV; volume of air that remains in the
lungs following a resting inspiration
d. total lung capacity (5,800mL) – VC+RV
8. Some of the air that enters the respiratory
tract during breathing does not reach the
alveoli. This volume (about 150mL)
remains in passageways of the trachea,
bronchi, and bronchioles. Because gas is
not exchanged through the walls of these
passages, the air is said to occupy
anatomic dead space.
Control of Breathing
• neural factors
– pons and medulla oblongata
• chemical factors
– central chemoreceptors
– peripheral chemoreceptors
– mechanoreceptors
Control of Breathing
Control of Breathing
Normal breathing is a rhythmic, involuntary act that continues even
when a person is unconscious. The respiratory muscles, however,
are under voluntary control.
Respiratory Center – located in the brain stem, and includes the pons
and medulla oblongata
1. Medullary Rhythmic Area
a. dorsal respiratory group – neurons that
control the basic rhythm of breathing
b. ventral respiratory group – quiet during normal
breathing; generate impulses that increase inspiratory
movements when more forceful breathing is required; other
neurons in the group activate muscles associated with
forceful expiration
2. Pneumotaxic Area – control breathing rate by continuously
transmitting impulses to the dorsal respiratory group; when
signals are strong, the inspiratory burst are shorter, and breathing
rate increases; when signals are weak, the inspiratory burst are
longer, and the breathing rate decreases
Factors Affecting Breathing
1.
Chemosensitive areas (central chemoreceptors) that
are associated with the respiratory center
a. Blood concentrations of carbon dioxide and
hydrogen ions influence these receptors to signal
the respiratory center, so that respiratory rate and
tidal volume will increase
2. Peripheral chemoreceptors are in the walls of certain
arteries
a. These receptors sense low oxygen concentrations
and increase breathing rate.
3. Overstretching lung tissues triggers an inflation reflex
a. helps regulate depth of breathing by shortening the
duration of inspiratory movements
b. prevents overinflation of the lungs during forceful
breathing
4. Hyperventilation – decreases blood carbon dioxide
concentrations; but is very dangerous when done
before swimming underwater
Alveolar Gas Exchange
1.
2.
3.
Alveoli – microscopic air sacs clustered at the distal
ends of the narrowest respiratory tubes, the alveolar
ducts. They carry on vital processes of exchanging
gases between air and blood.
Respiratory membrane – two thicknesses of simple
squamous epithlial cells and a layer of fused basement
membranes separate the air in the alveolus from blood
in the capillaries
Diffusion across the Respiratory Membrane
a. The parietal pressure of a gas is proportional to the
concentration of that gas in a mixture or the
concentration dissolved in a liquid.
b. Gases diffuse from regions of higher partial
pressure toward regions of lower partial pressure.
c. Oxygen diffuses from alveolar air into blood. Carbon
dioxide diffuses from blood into alveolar air.
Gas Transport
Oxygen transport
1. Blood mainly transports oxygen in
combination with hemoglobin molecules.
2. The resulting oxyhemoglobin is unstable and
releases its oxygen in regions where the
oxygen is low due to cellular respiration
3. More oxygen is released as the blood
becomes more acidic, and blood
temperature increases
Gas Transport cont…
Carbon Dioxide Transport
1. Carbon dioxide may be carried in solutions, bound to
hemoglobin (the globin part), or as a bicarbonate
ion.
2. Most carbon dioxide is transported in the from of
bicarbonate ions.
3. The enzyme carbonic anhydrase speeds the reaction
between carbon dioxide and water to form carbonic
acid.
4. Carbonic acid dissociates to release hydrogen ions
and bicarbonate ions.
5. The bicarbonate ions diffuse out of red blood cells and
enter the plasma. Nearly 70% of the carbon dioxide
that blood transports is in this form and the other
30% is given off when we exhale.
Surfactant Production
Babies are considered premature if they are born before 37
weeks gestation.
Fetuses begin to produce surfactant between weeks 24
and 28. By about 35 weeks, most babies have enough
naturally produced surfactant to keep the alveoli from
collapsing.
Babies born before 35 weeks, especially those born very
prematurely (before 30 weeks), are likely to need surfactant
replacement therapy. Over half the babies born before 28
weeks gestation need this treatment, while about one-third
born between 32 and 36 weeks need supplemental
surfactant.
Chapter 9: The Respiratory System
Lesson 9.3
Respiratory Disorders
and Diseases
Respiratory Disorders and
Diseases
•
•
•
•
•
upper respiratory tract illnesses
lower respiratory tract illnesses
chronic obstructive pulmonary diseases
asthma
lung cancer
Upper Respiratory Tract
Illnesses
Upper Respiratory Tract
Illnesses
• avoiding URIs
– cover when
sneezing and
coughing
– wash hands
– don’t touch hands to
eyes, nose, mouth
• influenza
– vaccine
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Lower Respiratory Tract
Illnesses
• acute bronchitis
– inflammation
• pneumonia
– infection
• tuberculosis
– infection
COPD
(Chronic Obstructive Pulmonary Disease)
Exemplified by:
Chronic bronchitis
Emphysema
Features of these 2 diseases:
1. History of smoking
2. Dyspnea (difficult or labored breathing)
3. Coughing and frequent infections
4. Hypoxic (retain CO2and have respiratory
acidosis)
Chronic Obstructive Pulmonary
Diseases
• causes
– smoking
• living with COPD
– stop smoking
– purse-lipped breathing
Chronic Obstructive Pulmonary
Diseases
• emphysema
– decreased lung surface area
– pink puffers
• chronic bronchitis
– inflammation obstructs airways
– blue bloaters
Asthma
• asthma attack
– inflamed and
narrowed airways
– bronchospasms
– caused by allergens
or irritants
– treatment relaxes
muscles to expand
airways
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Lung Cancer
• more deaths from lung cancer than other
cancers
• non-small cell lung cancer
– more common lung cancer
• small cell lung cancer
– less common lung cancer
Lung Cancer