Respiration 03 Info]

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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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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

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