breathing and exchange of gases Flashcards
mechanisms of breathing depends on what among different groups of animals?
based on their habitats and their levels of organization
lower invertebrates: sponges colentrates and flatworms mechanism of breathing?
simple diffusion over their entire body surface
earthworm mechanism of breathing?
moist cuticle
insects mechanism of breathing?
tracheal tubes
aquatic arthropods and molluscs mechanism of breathing?
gills ( branchial respiration)
amphibians, reptiles, birds and mammals mechanism of breathing?
lungs ( pulmonary respiration)
amphibians like frog mechanism of breathing?
cutaneous respiration (moist skin)
portion which is common for both food and air in human respiratory system
pharynx
what is sound box
larynx which is a cartilaginous box
epiglottis function
it prevents the entry of food into the larynx by its thin elastic cartilaginous flap
trachea location
it extends up to the mid thoracic cavity and divides at the level of 5th thoracic vertebra
human respiratory system pathway
nostrils - nasal passage - nasal chamber - pharynx - larynx -trachea - left and right primary bronchi - secondary and terminally bronchioles - alveoli
what comprises the lungs
the branching network of bronchi, bronchioles and alveoli
lungs are covered by
double layered pleura with pleural fluid between them
what is the role of pleural fluid
to reduce friction
outer pleural membrane surface is in close contact with
thoracic lining
the inner pleural membrane is in close contact with
lung surface
what is the conducting part
external nostrils to the terminal bronchioles
what is the function of conducting part
-it transports atmospheric air in to the alveoli
-clears it from foreign particles
-humidifies and also brings air to body temperature
what is the respiratory part or exchange part
alveoli and their ducts
what is the function of exchange part
actual site of diffusion of o2 and co2 between blood and air
where are lungs situated
in the thoracic chamber which is anatomically tight chamber
where is thoracic chamber formed
dorsally by the ventral column
ventrally by the sternum
laterally by the ribs
and on the lower side of the dome shaped diaphragm
what is the anatomical setup in the thoracic cavity
any change in the volume of thoracic cavity will be reflected in pulmonary cavity . it is essential for breathing as we CANNOT directly alter the pulmonary volume
inspiration can occur if
intrapulmonary pressure( lung pressure )is less than atmospheric pressure
expiration can occur if
when intrapulmonary pressure is higher than atmospheric pressure
what helps in the generation of pressure gradient
diaphragm and specialized set of muscles -external and internal intercostal between the ribs
inspiration is initiated by
contraction of diaphragm which increases volume of thoracic chamber in antero posterior axis
contraction of external inter costal muscles lift up the ribs and sternum and increase the volume in dorso ventral axis
what initiates expiration
relaxation of the diaphragm and inter costal muscles returns the diaphragm and sternum to their normal positions. this reduces the thoracic volume so the pulmonary volume. thereby increase in pulmonary pressure.
what is the role of additional muscles in the abdomen
it has the ability to increase the strength of inspiration and expiration
on an average a healthy human breathes
12-16 times/minute
the volume of air involved in breathing movements can be estimated by
spirometer
tidal volume TV
volume of air inspired or expired during normal respiration
approx: 500ml
6000-8000ml of air per minute
IRV
additional volume of air a person inspires by a forcible inspiration
2500-3000ml
ERV
additional volume a person expire by forcible expiration
1000-1100ml
RV
volume of air remaining in lungs after forcible expiration
1100-1200ml
IC
total volume of air a person can inspire after normal expiration
TV+IRV
EC
total volume a person can expire after normal inspiration
TV + ERV
FRC
volume of air that remain in lungs after normal expiration
ERV+RV
VC
maximum volume of air a person can breathe in after a forced expiration
ERV+TV+IRV
TLC
total volume of air accommodated in lungs at end of forced inspiration
RV+ERV+TV+IRV or VC+RV
what are the volumes which cannot be measured by spirometer
FRC, RV AND TLC
what are the primary sites of exchange of gases
alveoli
o2 and co2 diffusion between blood and tissues is mainly based on
pressure or concentration gradient
what are the important factors that can affect the rate of diffusion
solubility of gases
thickness of the membrane
oxygen pathway
alveoli to blood to tissues
co2 pathway
tissues to blood to alveoli
how much times higher is co2 solubility than that of o2
20-25 times higher
what are the diffusion membrane layers
thin squamous epithelium of alveoli
endothelium of alveolar capillaries
basement substance
basement membrane is composed of
thin basement membrane supporting the squamous epithelium and basement membrane surrounding the single layer of endothelial cells
total thickness of membrane
less than a millimeter
what is the medium of transport for o2 and co2
blood
transport of o2 by rbcs
97%
transport of o2 in dissolved state of plasma
3%
transport of co2 by rbc
20-25%
transport of co2 by bicarbonate
70%
transport of co2 by dissolved state through plasma
7%
o2 bind with haemoglobin to form
oxyhemoglobin
each haemoglobin can carry a maximum of
4 molecules of o2
favorable condition for formation of oxyhaemoglobin
low po2, high pco2, high H^+ concentration, high temperature
every 100ml of oxygenated blood can deliver
5ml of o2
factors favourable for carbamino haemoglobin
high pco2, low po2
for dissociation of co2 bound to haemoglobin
low pco2, high po2
rbcs contain very high concentration of an enzyme called
carbonic anhydrase
every 100ml of deoxygenated blood delivers
4ml of co2 to alveoli
asthma
inflammation of bronchi and bronchioles
difficulty in breathing due to wheezing
emphysema
chronic disorder
alveolar walls are damaged due to which respiratory surface is decreased
cause: cigarette smoking
occupational respiratory disorder
proliferation of fibrous tissues : fibrosis
center present in medulla region responsible to maintain and moderate respiratory rhythm
respiratory rhythm center
what moderates the functions of RRC
center present in pons region of brain called pneumotaxic centre
it can reduce duration if inspiration and thereby alter respiratory rate
what is adjacent to rhythm centre
a chemosensitive area is situated which is highly sensitive to co2 and hydrogen ions
increase in these substances activate RRC
which receptors can also recognize changes in co2 and H+ concentration
aortic arch and carotid arch
