Respiratory System Exchange of oxygen and carbon dioxide between the blood and the muscle tissues...
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Transcript of Respiratory System Exchange of oxygen and carbon dioxide between the blood and the muscle tissues...
Respiratory SystemRespiratory System
Exchange of oxygen and carbon
dioxide between the blood and the muscle tissues
Exchange of oxygen and carbon dioxide between the lungs and blood
The breathing of air into and out of the lungs
Mechanics of Mechanics of BreathingBreathing
Inspiration: External intercostals muscles contract during
inspiration Diaphragm contracts (downwards and flattens) This pulls the rib cage upwards and outwards These actions cause the thoracic cavity size to increase This decreases the pressure inside the thoracic cavity Gases move from areas of high pressure to low
pressure areas Therefore oxygen moves from the atmosphere (higher
pressure) into the lungs (now low in pressure) During exercise, a more forceful inspiration is required
so extra muscles are involved in this process – sternocleidomastoid and pectoralis minor
Expiration Usually a passive process As the intercostals muscles relax the rib cage
moves downwards The diaphragm relaxes and returns to its dome
shape This decreases the size of the thoracic cavity This causes the pressure to increase in the thoracic
cavity (smaller volume) Therefore gases move out of the lungs (high
pressure) into the atmosphere (lower pressure) During exercise breathing rate is increased,
expiration is aided by the internal intercostal muscles and the abdominal muscles,
This pulls the rib cage down more quickly and with greater force
Gaseous ExchangeGaseous Exchange
Key Terms: Gaseous Exchange – the process of
exchanging O2 and CO2 Partial Pressure - the pressure a gas exerts
in a mixture of gases Diffusion - The movement of gases from areas
of higher partial pressure to lower partial pressure
Diffusion Gradient - The difference between high and low pressure of gases. The bigger the gradient the greater the diffusion.
External RespirationExternal Respiration
Involves the movement of oxygen and carbon dioxide between the alveoli of the lungs and capillaries surrounding the alveoli.
The aim of external respiration is to oxygenate the blood returning from the tissues
As blood circulates through the capillaries surrounding the alveoli oxygen is picked up and carbon dioxide is dropped off to be expired
Internal RespirationInternal Respiration
Involves the movement of O2 and CO2 between the capillaries surrounding the muscles and the muscle tissues
The aim of internal respiration is to oxygenate the muscles and collect CO2 to return it to the alveoli
These processes can only happen if a diffusion gradient is present.
External and Internal External and Internal Respiration Showing Respiration Showing
Changes in O2 and CO2Changes in O2 and CO2
Oxygen-Haemoglobin Oxygen-Haemoglobin Dissociation CurveDissociation Curve
Shows us how much haemoglobin is saturated with oxygenSaturated – when haemoglobin is loaded with oxygenDissociation – where oxygen is unloaded from the haemoglobinThe higher the partial pressure of oxygen, the higher percentage of oxygen saturation to haemoglobin
Oxygen associates with haemoglobin at the lungs and dissociates at the muscles (because PP of O2 is high at lungs and low at muscles)
During exercise a greater amount of dissociation of O2 at the muscles is required, therefore less saturation at the muscles has to occur
Four factors happen in our bodies during exercise to allow this to occur
Factors Affecting the Factors Affecting the saturation of oxygen to saturation of oxygen to
haemoglobinhaemoglobin Increase in temperature – in the blood and muscles
during exercise Decrease in PP of O2 – within the muscles during
exercise, therefore creating a greater diffusion gradient
Increase in PP of CO2 – therefore causing a greater CO2 diffusion gradient
Increase in acidity – lowering the pH of the blood through production of lactic acid (more hydrogen ions produced). This is known as the BOHR SHIFT
All four of these factors (which occur during exercise) increases the dissociation of oxygen from haemoglobin, which increases the supply of oxygen to the working muscles and therefore delays fatigue..
Exam Style Question: What happens to the oxygen-Haemoglobin
Dissociation Curve during exercise? (6 marks)
It shifts to the right Because during exercise there is an
increase in blood/muscle temperature Decrease in PP of O2 in the muscles Increase in PP of CO2 in muscles Increase in acidity (more lactic acid) Known as Bohr Effect/Shift
MyoglobinMyoglobin
Has a higher affinity for O2 than haemoglobin
Therefore acts as a store of O2 Even at very low partial pressures of
02 (the muscles when exercising) it remains saturated
This means that myoglobin still has O2 available to supply the working muscles.
Respiratory Adaptations to Respiratory Adaptations to TrainingTrainingReduction in breathing rate during
sub-maximal exercise,System is more efficient therefore less breaths required,No changes in lung volumes except. . . .Vital capacity – amount of air that air that can be forcibly expired after can be forcibly expired after maximal inspirationmaximal inspiration – increases – increases slightly, largely due to stronger slightly, largely due to stronger respiratory musclesrespiratory musclesTherefore spirometer traces are Therefore spirometer traces are not good predictors of training or not good predictors of training or fitness because lung size/volume do fitness because lung size/volume do not determine fitness (these are not determine fitness (these are largely genetic and not adapted due largely genetic and not adapted due to training)to training)
Gaseous exchange becomes efficient
External Respiration - increased capilliarisation surrounding alveoli – more opportunity for gaseous exchange to occur, more O2 enters the blood
Internal Respiration – increase in myoglobin within the muscles (this carries O2 to mitochondria), therefore leading to improved efficiency of energy production.
Describe the chemical, physical Describe the chemical, physical and neural changes that cause a and neural changes that cause a
change in our breathing rate.change in our breathing rate. Chemical – Increase in CO2, increase in acidity Detected by chemoreceptors Physical – Movement of muscles and joints Detected by proprioreceptors Also stretch receptors in lungs, temperature receptors
detect changes Neural – Nervous control Messages sent to the medulla (respiratory control centre) Messages to send respiratory muscles via sympathetic
nervous system.
Respiratory System so Respiratory System so far . . .far . . .
1. What is the Oxygen-Haemoglobin Disassociation Curve?
2. What happens to the curve during exercise?
3. What causes this to happen?4. What are the effects of the curve
shifting to the right?5. What changes occur to the respiratory
system as a result of training?
Lung Volumes (Average male) ** Learn
Volume Name Description Value at Rest (ml)
Change during
Exercise
Tidal Volume (TV)
Amount of air breathed in or out per breath
500 Increases
Inspiratory Reserve Volume
(IRV)
Maximal amount of air forcibly inspired in
addition to tidal volume
3100 Decreases
Expiratory Reserve Volume
(ERV)
Maximal amount of air forcibly expired in
addition to tidal volume
1200 Decreases
Vital Capacity (VC)
Maximal amount of air exhaled after a maximal
inspiration(TV + IRV + ERV)
4800 Slight
Residual Volume (RV)
Amount of air left in the lungs after a maximal
expiration
1200 None
Total Lung Capacity (TV)
Vital Capacity plus residual volume
(TV + IRV + ERV + RV)
6000 none
Effects of Exercise on Volumes
At rest, lungs are ventilated at approx. 6 Litres per minute During “steady state” endurance exercise maximal ventilation
is about 80-100 Litres per minute (males) and 45-80 Litres per minute (females) – smaller lungs!
Brief maximal exercise (800m race) rates may increase to 120-140 Litres per minute
BREATHING RATES – rise from 12 per minute to 45 per minute during strenuous exercise
Depth of respiration can increase from 0.5 litres per breath to 2.5 litres per breath
Training will usually result in little or no change in pulmonary function. However, swimmers may experience some increase in vital capacity and maximal breathing capacity (breathing
against resistance of the water)Comparison of marathon runners and sedentary subjects showed
no difference in actual lung functions (FEV1, etc)
Summary The respiratory system functions to deliver O2 to the lungs and
remove CO2 The system consists of the nose, trachea, larynx, bronchial tree
and lungs Inspiration occurs when air is drawn into the lungs by the
reduction of the pressure caused by an increase in the size of the thoracic cavity
Expiration occurs when the pressure increases as the size of the thoracic cavity decreases and air is forced out
During normal breathing inspiration is produced by the activity of the diaphragm and intercostal muscles
During exercise both the rate and depth of breathing increase Respiration is controlled by the MEDULLA of the brain Total Lung Capacity = Tidal Volume + Inspiratory Reserve
Volume + Expiratory Reserve Volume and Residual Volume (6000ml)