Transcript A View of Life

Respiratory System
1
Outline
•
•
•
•
The Respiratory Tract
– The Nose
– The Pharynx
– The Larynx
– The Bronchial Tree
– The Lungs
Gas Exchange
Mechanisms of Breathing
– Inspiration and Expiration
Respiration and Health
2
The Respiratory System
•
•
During inspiration or inhalation, air is
conducted toward the lungs.
During expiration or exhalation, air is
conducted away from the lungs.
3
The Respiratory System
•
The respiratory system works with the
cardiovascular system to accomplish
respiration.
– Breathing.
– External respiration.
– Internal respiration.
– Cellular respiration.
4
The Respiratory Tract
•
•
As air moves towards the lungs it is
cleansed, warmed, and moistened.
As air moves out during expiration, it cools
and deposits moisture on the lining of the
trachea and the nose.
5
The Respiratory Tract
6
The Nose
•
The nose contains two nasal cavities that
empty into the nasopharynx.
– Tear glands drain into the nasal cavities.
– Auditory tubes lead from the nasopharynx
to the middle ears.
7
The Pharynx
•
•
The pharynx is a funnel-shaped
passageway that connects the nasal and
oral cavities to the larynx.
Three sections.
– Nasopharynx - Nasal cavities open above
soft palate.
– Oropharynx - Oral cavity opens.
– Laryngopharynx - Opens into the larynx.
8
The Path of Air
9
The Larynx
•
•
•
The larynx serves as a passageway for air
between the pharynx and the trachea.
– When food is swallowed, the larynx
moves against the epiglottis preventing
food from passing into the larynx.
The larynx houses the vocal cords which are
stretched across the glottis.
The trachea is a tube connecting the larynx
to the primary bronchi.
10
Placement of the Vocal Cords
11
The Bronchial Tree
•
The trachea divides into left and right
primary bronchi which eventually branch into
secondary bronchi and then into
bronchioles.
– Each bronchiole leads to an elongated
space enclosed by alveoli.
12
The Lungs
•
The lungs lie on either side of the heart
within the thoracic cavity.
– Right lung has three lobes and the left
lung has two lobes.
 Each lobe is divided into lobules, further
divided into bronchioles serving many
alveoli.
13
Gas Exchange in the Lungs
14
Mechanism of Breathing
•
Respiratory Volumes
– Tidal volume is the amount of air that
moves in and out with each breath.
– Vital capacity is the maximum amount of
air that can be moved out in a single
breath.
 Inspiration can be increased by
expanding the chest (inspiratory
reserve volume).
15
Respiratory Volumes
Vital Capacity
 Expiration can be increased by
contracting the abdominal and thoracic
muscles (expiratory reserve volume).
Residual volume is the air remaining in the
lungs after deep exhalation.
–
•
16
Vital Capacity
17
Inspiration and Expiration
•
Ventilation
– Normally there is a continuous column of
air from the pharynx to the alveoli.
– Lungs lie within sealed thoracic cavity.
 Rib cage forms top and side of the
cavity, while the diaphragm forms the
floor.
– Lungs are enclosed by two membranes,
pleura.
18
Inspiration
•
•
A respiratory center is located in the medulla
oblongata and triggers inspiration.
Inspiration is the active phase of breathing.
– The diaphragm and the rib muscles
contract, intrapleural pressure decreases,
the lungs expand, and air rushes in.
 Creation of a partial vacuum in the
alveoli causes air to enter the lungs.
19
Expiration
•
•
When the respiratory center stops sending
signals to the diaphragm and the rib cage,
the diaphragm relaxes.
– Abdominal organs press up against the
diaphragm, and the rib cage moves down
and inward.
Expiration is usually passive as the
diaphragm and external intercostal muscles
are relaxed.
20
Inspiration Versus Expiration
21
Gas Exchanges in the Body
•
External respiration refers to gas exchange
between air in the alveoli and blood in the
pulmonary capillaries.
– Blood entering the pulmonary capillaries
has a higher partial pressure of carbon
dioxide than atmospheric air.
 Carbon dioxide diffuses out of the blood
into the lungs.
– The pressure pattern is the reverse for
oxygen.
22
Internal Respiration
•
Internal respiration refers to gas exchange
between the blood in systemic capillaries
and the tissue fluid.
– Oxygen diffuses out of the blood into the
tissue because the partial pressure of
oxygen of tissue fluid is lower than that of
blood.
23
24
Binding Capacity of Hemoglobin
•
Binding capacity of hemoglobin varies
according to the environmental conditions in
the lungs and tissues.
– If the binding capacity of hemoglobin is
high, hemoglobin will be saturated with
oxygen.
– The binding capacity of hemoglobin for
oxygen is affected by the partial pressure
of oxygen, temperature, and pH.
25
Respiration and Health
•
Upper Respiratory Tract Infections
– Sinusitus - Infection of cranial sinuses.
– Otitis Media - Bacterial infection of middle
ear.
– Tonsillitis - Inflammation and enlargement
of tonsils.
– Laryngitis - Infection of larynx with
hoarseness and inability to talk.
26
Respiration and Health
•
Lower Respiratory Tract Infections
– Acute bronchitis - Infection of primary and
secondary bronchi.
– Pneumonia - Viral or bacterial infection of
the lungs.
– Pulmonary tuberculosis - Tubercle bacillus
bacterium.
27
Respiration and Health
•
•
Restrictive pulmonary disorders - Vital
capacity is reduced because lungs have lost
elasticity.
– Pulmonary fibrosis.
Obstructive pulmonary disorders - Air does
not flow freely in the airways.
– Chronic bronchitis.
– Emphysema.
– Asthma.
– Lung cancer.
28
Review
•
•
•
•
The Respiratory Tract
– The Nose
– The Pharynx
– The Larynx
– The Bronchial Tree
– The Lungs
Gas Exchange
Mechanisms of Breathing
– Inspiration and Expiration
Respiration and Health
29
30