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The Physiology of Respiration
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RESPIRATIONThe exchange of gases between theatmosphere, blood and cells.Involves three processes
Pulmonary ventilation- inspiration andexpiration.External respiration- the exchange of gasbetween the lungs and blood.
Internal respiration- the exchange of gasesbetween the blood and cells.
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Why do we need to breathe?
Breathing gets oxygen into the body so that cells canmake energy
Cells use this energy to contract muscles and powerthe thousands of biochemical reactions that takeplace in the cell every second
Without oxygen, cells cant make energy and without
energy, cells would die
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IMPORTANT CONCEPTThe supply of blood and oxygen to cellsand tissues is called PERFUSION
If perfusion stops then cells die
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Energy productionInside the cells most energy is made by themitochondria. This energy is in the form of ATP*
*adenosine triphosphate a small packet ofenergy
In the process of energy production
Oxygen is consumed by the cells
Carbon dioxide is produced as a waste gas
Glucose fuels the process
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O2
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Mitochondrion
O2
Glycolysis
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Electron TransportChain
e-e-
Mitochondrion
Membrane (close-
H+H
+ H+
H+ H
Krebs Cycle
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Making ATP
e-
H+
H+H+
H+
H+
H+
H+H+
O O
O
HH
Water Made
ATPSynthase
Enzyme
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How do cells get their oxygen?
Oxygen (O2) from the air in the lungs diffusesinto the blood
It is transported in the blood to the cells
Oxygen diffuses from the blood into the cells
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Movement of O2 and CO2 between
lungs and cells
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The anatomy of the Respiratory
System
The respiratory system consists of a series oftubes that transfer air from outside the bodyto the small air sacs in the lungs where gasexchange take place the alveoli
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Look at thestructure of the
respiratorysystem and labelthe diagram in
your workbook
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Alveoli
At the end of the smallest bronchioles are thealveoli
There are millions of alveoli in each lung
Alveoli are surrounded by a network of smallblood vessels called capillaries
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Alveoli and adjacent capillaries
terminal bronchiole
alveoli
capillaries
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Gas exchange in the alveoli
Oxygen diffuses from the alveoli to the
blood in the capillaries
Carbon dioxide diffuses from the blood inthe capillaries to the alveoli
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W
hat is diffusion?Diffusion is a process that occurs when there isa difference in the concentration of a substancebetween two areas
The substance, for example oxygen, will diffusefrom an area of high concentration to an areaof low concentration
No energy is required from the body for thisprocess
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Partial pressure
The pressure exerted by each type of gas in a
mixture
Diffusion of gases through liquids
Concentration of a gas in a liquid is determined
by its partial pressure and its solubility
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oconcentration o p opp of gas p odiffusion
CO2 more soluble than O2, therefore it
diffuses faster
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Oxygen and Carbon Dioxide
Diffusion Gradients
Oxygen
Moves from alveoli into
blood. Blood is almost
completely saturated
with oxygen when it
leaves the capillary
P02
in blood decreases
because of mixing with
deoxygenated blood
Oxygen moves from
tissue capillaries into the
tissues
Carbon dioxide
Moves from tissues
into tissue capillaries
Moves frompulmonary capillaries
into the alveoli
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23-29
Oxygen and Carbon Dioxide
Diffusion Gradients
Oxygen
Moves from alveoli into
blood. Blood is almost
completely saturated
with oxygen when it
leaves the capillary
P02
in blood decreases
because of mixing with
deoxygenated blood
Oxygen moves from
tissue capillaries into the
tissues
Carbon dioxide
Moves from tissues
into tissue capillaries
Moves frompulmonary capillaries
into the alveoli
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Changes in Partial Pressures
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Ventilation (breathing)
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Ventilation (breathing)
Inspiration (breathing in)
Ribs rise and diaphragm flattens
Volume increases and pressure decreases
Air enters the lungs
Expiration (breathing out)
Ribs fall and diaphragm domes
Volume decreases and pressure increases
Air leaves the lungs
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Mechanics of Breathing Inhaling (active process) Air moves in. Why??
Gases move from an area of high pressure to low
pressure During inspiration diaphragm pulls down and lungs
expand
When lungs expand, it INCREASES the VOLUME,
which DECREASES the PRESSURE inside lungs
Lung pressure is lower than outside pressure, so air
moves in
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Exhaling (passive process) breathing out
Diaphragm and muscles relaxVolume in lungs and chest cavity decreases,
so now pressure inside increases
Air moves out because pressure inside isHIGHER than OUTSIDE atmosphere
Mechanics of Breathing
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Respiration
What is respiration?
External respiration exchange ofO2
and
CO2between respiratory surfaces and the
blood (breathing)
Internal respiration exchange ofO2
and
CO2between the blood and cells
Cellular respiration process by which cells
useO2 to produce ATP
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External Respiration Exchange ofO2 and CO2between alveoli andblood
Partial pressure ofO2 higher in alveoli thanblood so O2 diffuses into blood
Partial pressure of CO2 higher in blood than
alveoli, so CO2 moves into alveoli in oppositedirection and gets exhaled out
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Internal Respiration
Exchange ofO2 and CO2between blood and tissues
Pressure ofO2
higher in blood than tissues soO2
gets release into tissues.
Pressure of CO2 higher in tissue than in blood so
CO2 diffused in opposite direction into blood.
CO2Is a waste product
O2Is used in cellular respiration
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Control of Ventilation
As we exercise, the body needs to obtainmore oxygen and remove more carbondioxide (CO2)
This is done by increasing the rate anddepth of breathing
An increase in carbon dioxide in the blood is
the main trigger that increases the rate anddepth of breathing
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respiratorycentres inmedulla
chemoreceptorson aorta andcarotid artery
heart
brain
intercostalnerve toexternalintercostalmuscles
phrenic
nerve todiaphragm
diaphragm
ribs
Control of Respiration
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Diseases such as emphysema, bronchitis andasthma can impede the movement of gasbetween the alveoli and the blood
CO2 levels can build up in the blood known as hypercapnia
This stimulates the chemoreceptors inthe respiratory centre of the brain
The rate and depth of breathing increasesto expire more CO2 and reduce levels in theblood
Response to hypercapnia