Download Respiratory System - Wando High School

Respiratory System
Respiratory System

Major function is to supply the body with
oxygen and dispose of carbon dioxide

Most of the carbon dioxide waste is used
as blood’s buffer system
4 Processes of Respiration

Pulmonary ventilation: movement of air
into and out of the lungs so that gases are
continuously refreshed.

External respiration: movement of oxygen
from the lungs to the blood and of carbon
dioxide from the blood to the lungs
4 Processes cont.

Transportation: movement of oxygen to
the tissues and carbon dioxide from the
tissues to the lungs.

Internal respiration: movement of oxygen
from blood to the tissue cells and of
carbon dioxide from the cells to blood.
Atmospheric Gas: mixture

Nitrogen: 78%
◦ Must be eaten to obtain for body
◦ Nitrogen is fixed by bacteria for plants to absorb
◦ Nitrogen is introduced to the soil also through
lightning

Oxygen: 20.9%
◦ Combustible at 22%
◦ Released by organisms that perform
photosynthesis
◦ Used by organisms for cellular respiration
Atmospheric Gases, cont.

Carbon dioxide: 0.04%
◦ Waste product of cellular respiration
◦ Carbon dioxide comes from pollution
◦ Green organisms use CO2 for photosynthesis
Water Vapor: 0.46%
 Percentage of water vapor in air is called
dewpoint

◦ Higher the dewpoint = higher the humidity
Respiratory System Parts

1. nose: external portion supported by
bone and cartilage
◦ Internal nasal cavity is divided by the septum
and lined with mucosa.
◦ Roof is lined with olfactory epithelium
◦ Terbinate bone line the nasal cavity
◦ Produce mucus, filter, warm, and humidify the
incoming air, resonance chamber for speech.
Parts, cont.

2. paranasal sinuses: mucosa lined air-filled
cavities
◦ Decreases the weight of the skull, and
performs the same functions as the nose
Parts, cont.

3. Pharnyx: back of the throat.
◦ 3 divisions: nasopharynx. Oropharnyx, and
laryngopharynx
◦ Houses the tonsils- lymphoid tissue

Passageway for both food and air
Parts, cont.

4. Larynx: connects the throat to the
trachea
◦ Contains a cartilage framework that includes
the epiglottis
◦ Epiglottis closes over the trachea when
swallowing
◦ Houses vocal cords

Air passageway into the lower respiratory
tract
Parts, cont.

Trachea: flexible tube connecting the
larynx and the bronchi
◦ Walls contain C-shaped cartilage rings that
are incomplete posteriorly
(keep the airway open)
◦ **air passageway, cleans,
warms, and moistens
the incoming air
Parts, cont.

Bronchial tree: right and left bronchi that
subdivides into the bronchioles
◦ Has the same function as the trachea, can
become inflamed and can restrict air flowasthma
Parts, cont.

Alveoli: microscopic chambers at
terminal bronchioles
◦ Walls are simple squamous epithelium
◦ Site of gas exchange
Parts, cont.

Pleurae membranes
◦ Produces surfactant; lubricating solution that
decreases friction
Mechanics of Breathing
Remember Boyle’s Law???
 If the volume increases, then the pressure
must decrease (or vice versa)


P1V1 = P2V2
Breathing occurs when the contraction or
relaxation of muscles around the lungs
changes the total volume of air within the
air passages (bronchi, bronchioles) inside
the lungs.
 When the volume of the lungs changes,
the pressure of the air in the lungs
changes in accordance with Boyle’s Law.


If the pressure is greater in the lungs than
outside the lungs, then air rushes out. If
the opposite occurs, then air rushes in.
Mechanics of Breathing: Inspiration
Diaphragm contracts and lowers, thus
increasing the size of the thoracic cavity.
 External intercostal muscles contract
elevating the ribs and sternum.
 Total volume of internal air passages
increases, air pressure inside the lungs
decreases below that of air outside the body.
 Because gases move from regions of high
pressure to low pressure, air rushes into
the lungs.

Mechanics of Breathing: Expiration
Diaphragm relaxes and raises, thus
decreasing the size of the thoracic cavity.
 External intercostal muscles relax lowering
the ribs and sternum.
 Elastic fibers cause the lungs to recoil to
original volume
 Total volume of internal air passages
decrease, air pressure inside the lungs
increases below that of air outside the body,
air rushes out.


https://www.youtube.com/watch?v=F0OB
kR00OZE
Control of Breathing

The autonomic nervous system controls
breathing.

The respiratory center that controls the
rate of breathing is in the medulla.
Factors that influence the Medulla

Oxygen:
◦ Peripheral chemoreceptors located in the carotid
and aorta detect the amount of oxygen in the
blood. If the oxygen concentration is low, they tell
the medulla to increase breathing.

Carbon dioxide:
◦ These receptors also monitor carbon dioxide
levels in the CSF. If too high, then signals are sent
to respiratory centers to increase the rate and
depth of breathing.
Other Factors that influence the
Medulla

pH:
◦ If the blood becomes too acidic, then signals
are sent to the centers to speed up

Stretch:
◦ If the lungs are overinflated, respiratory
centers are signaled to exhale

Signals from brain centers:
◦ Nerve cells in the hypothalamus and cortex
◦ During pain or strong emotions,
hypothalamus tells the centers to speed up,
slow down, or stop