Download Respiration and Circulation - Greater Atlanta Christian Schools

Oxygen is essential for the existence of
animals
 All oxygen in the air comes from the
process of photosynthesis
 Air consists of:
 Nitrogen-78.09%
 Oxygen-20.95%
 Inert gasses-0.93 %
 Carbon dioxide-0.03%

Purpose: to obtain oxygen and remove
carbon dioxide from the body
 Gases are exchanged across
membranes, through water by
diffusion(surfaces must be wet)
 Gases are then distributed by the
circulatory system

Diffusion of oxygen is slow and only
diffuse over 0.5mm.
 Special organs had to be developed to
have larger organisms
 Protists can use simple diffusion because
of their size

Others use water currents to carry
oxygen across membranes
 Need large surface area
 Others developed internal organs to
provide contact between the outside
and internal circulation
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External gills V. Internal gills
External gills are outside of
the body and the many
branched gills are resistant
to water.
Internal are found in an
internal body cavity that
allow water to flow from
the mouth through the
cavity and out another
opening(creates a one
way current)

Gills would not work for terrestrial animals.
Why?
Amphibians –have primitive lung but can
also diffuse Oxygen through skin
(ectothermic-Oxygen needs low)
Reptiles-more active (need more Oxygen),
can't obtain oxygen through skin
therefore have more advanced lung with
greater surface area therefore have more
lung with greater surface area

Mammals have higher activity and
higher body temperature so Oxygen
needs are greater

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Air is breathed in by the nostrils
Nostrils are lined with hair and mucous
› These are used to trap invaders
› Air then passes nasal passages into the trachea.
› Trachea branches in to two bronchi.(one for each
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lung)
These bronchi continue branching into smaller and
smaller tubes.
The smallest are bronchioles
Bronchioles end in clusters of sacs called alveoli
All gas exchange takes place in the thin walled
alveoli
Total surface are of 6080 square meters
Rib intercostal muscles contract and
expand the rib cage
 Diaphragm contracts and increases the
volume of the thoracic cavity
 More volume means less pressure and air
rushes in

Diaphragm and intercostals relax and
decreases the volume of the thoracic
cavity
 This action increases the pressure in the
cavity
 This causes air to rush out of the lungs

Tidal Volume
 Amount of air in and out in a single
breath.
 Usually around 500ml.(can increase to
3000 with exercise)
 Inspiratory reserve volume(IRV) excess air
when breathing in maximumly
 Expiratory reserve volume(ERV) amount
of air when breathing out maximumly.

Vital capacity (VC)total lung volume
when breathing in and out maximumly.
 VC=IRV +TV +ERV
 Not all air is breathed out during
maximum expiration this residual
volume(RV)
 Total lung capacity:

› Y= VC + RV
Respiratory rate = number of breaths per
unit time.
 Such as Breaths/minute.
 respiratory rate and tidal volume =lung
ventilization
 TV X respiratory rate per minute
 Normal is 5L per minute but can be up to
1300L per minute during exercise

Controlled in brain by the breathing control
center(BRC)
 Automatic process

› BRC sends impulses to the intercostal muscles of
the rib cage and the diaphragm and we inhale
› When the signal stops we exhale.
› When breathing stops Carbon Dioxide levels rise
and trigger cells in the aorta and carotid arteries
to signal the BRC to breathe.
› In hyperventilation so much CO2 is removed that
the cells signal BRC to stop breathing
Allergens-cause release of histamines to
constrict airways
 Bronchitis-inflammation of the bronchiexcess mucous and retards ciliary action
 Emphysema-walls of alveoli become less
flexible and can be damages. This
reduces surface area for gas exchange.
 Caused by chronic bronchitis, infection,
genetics, and environmental
conditions(smoking)

Paralyzes cilia
 Stimulates mucous production
 Coughing helps, but still leads to
bronchitis and other lung illnesses
 Smoke contains substances that convert
to carcinogens in the body
 80% of lung cancer is caused by smoking
