Antrim PE Revision Course
AQA AS PHED 1
Session 3b
Applied Physiology – Respiration
& Cardiac Function
Respiration – need to know
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Mechanics of breathing
Different lung volumes and capacities
Interpret spirometer graphs
Oxygen and carbon dioxide exchange in lung
alveoli and muscles
• Process of diffusion
• Concept of partial pressure
Cardiac function – need to know
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Circulatory system
Role of haemoglobin, myoglobin
Venous return
The a-vO2 difference
Heart structure – cardiac cycle
Cardiac output, stroke volume, heart rate
Control of heart rate
Effects of training
Breathing
Quiet breathing – diaphragm+ intercostals
Deep breathing – sternocleidomastoid + pectorals
Chemo-receptors
Inflation of aleveoli
CO2
Medulla Oblongata
Respiratory
Respiratory
Inhibitory
Centre
Accelerator Centre
Autonomic
breathing
control
Sympathetic
Parasympathetic
(Acc nerve)
Vagus nerve
Lungs
Intercostal muscles
Diaphragm Contract
Respiration – Lung Volumes
June0
2Q3
Ans
Respiration - Ventilation
Ventilation = Tidal Volume x Frequency (breathing rate)
Frequency/Breathing rate:
Resting 12-18 min-1
Peak: 45-60 min-1
Tidal volume:
Resting 0.5L Peak: 2.25 L
Minute Ventilation
Resting: 6 lt/min-1 Peak:175 lt/min-1
Respiration - O2 Transport
Red Blood Cells
Haemoglobin > Oxyhaemoglobin
From alveoli – to muscle cell
boundary
Myoglobin > Oxymyoglobin
From muscle cell boundary >
mitochondria
A-V difference
Carbon dioxide
70-80% Bicarbonate carbonic
acid HCO3
5-10% Dissolved in plasma
5-10% Carbaminohaemoglobin
Arterial – Venous Oxygen Difference (a-VO2 diff)
Arterial
Blood
O 2%
Venous
Blood
O 2%
a-VO2
Diff
O 2%
Rest
20
15
5
Intense
Exercise
20
5
15
Jun02Q5
Ans
More
oxygen is
extracted by
working
muscles
O2
CO2
Gas
Exchange
PCO2 40mm Hg
Alveolus
PO2 104mm Hg
Capillary
PCO2 45mm Hg
PCO2 40mm Hg
PO2 40mm Hg
PO2 104mm Hg
Blood Flow in Capillary
Exercise and oxygen disassociation
Rise in
temperature
Bohr Shift
Shift
Bohr
% saturation Hamoglobin
% Saturation of Haemoglobin
100
100
Acidity rise
due to CO2 LA
increase
9090
8080
7070
6060
Rest
Rest
Exercise
5050
4040
3030
Curve moves
to the right
2020
1010
0 0
30 40
40 50
50
0 0 1010 2020 30
60
70
70 80
80 90
90 100
100
Jun02Q5
pO2(mm
mmHg)
Hg
pO2
Haemoglobin
disassociates oxygen
more readily
More O2 available
during exercise
Ans
Pulmonary and systematic circulation
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Arteries/arterioles/capillaries/venules and veins)
Generation of blood pressures/velocities
Venous return mechanism
Redistribution of blood/vascular shunting
Arterio – venous oxygen difference (A-VO2 diff).
Cardiac function
Cardiac cycle
Cardiac output, stroke volume and heart rate and the relationship
between them.
Heart rate range in response to exercise; hormonal and nervous
effects on heart rate;
Role of blood carbon dioxide in changing heart rate
Cardiac hypertrophy leading to bradycardia/athlete’s heart
Starling’s law of the heart
Cardio-vascular drift.
Arteries - thick
muscular walls;
take blood away
from heart - high
pressure; elastic
Invisible
on this
scale
Capillaries tiny, very thin
walls - diffusion
of substances in
and out
Venules
Arterioles
Blood vessels
Veins - thin
walled; carry
blood back to
heart - need
help - venous
return
Venous return
• One-way valves in veins
• Contraction of skeletal muscles during
movements – skeletal pump
• Compression of chest veins during inspiration,
and lowering of thoracic pressure –
respiratory pump
• ‘Suction pressure’ of heart
06-19
14
Dynamics of venous return
Muscle
pump
Respiratory
pump
Blood pressure and velocity
Blood
pressure
Arteries
Blood
velocity
Capillaries
Venules
Veins
Velocity falls
and rises –
with
increasing &
decreasing
total crosssectional
area
Pressure falls
- friction &
increasing
crosssectional
area
Total
crosssectional
area
Jun04Q5
Arterioles
Ans
Starlings Law
SV
Trained Heart
Normal
contractility
Left
ventricle
Venous return
Increased
venous
return
Increase
in
fibre
length
Increased stroke volume
Increasefilling
in contractility
Increased
of left ventricle
Trained heart will
contract more
powerfully
Ans
Blood Flow - Redistribution
Jan04Q1
Blood Flow in cm3 per minute
Liver & Gut
Area
Rest
Max
Muscles
1000
26000
Heart
250
1200
Skin
500
750
Kidneys
1000
300
Liver &
Gut
Brain
1250
375
750
750
Whole
5000
30000
Rest
Liver & Gut
Max Exercise
Blood Flow Redistribution - Volume
Blood Flow in cm3 per minute
Area
Rest
Max Ex
Muscles
Heart
1000
250
26000
1200
Skin
500
750
Kidneys
Liver &
Gut
Brain
Whole
1000
1250
300
375
750
5000
750
30000
Increase to skeletal
muscles & heart
Decrease to liver, gut,
kidneys
Brain stays same
Increase in total blood
flow (Cardiac Output)
SV+ HR+
Cardiac cycle
Contraction =
systole
Relaxation =
diastole
The order of
contraction
Diastole
Atrial
systole
High pressure (systole) in
chambers forces valves open
Valves close when pressure
drops again (diastole)
Ventricular
systole
Cardiac Output
Cardiac Output = Heart Rate x Stroke Volume
Q. = HR X SV
Stroke Volume - Volume of blood ejected each
contraction (systole) of the ventricle
Units!
Rest
60bpm x 83ml = 5000ml-1 (5 litres)
Max work (trained)
200bpm x 170ml = 34000ml-1(34 litres)
Cardiac Hypertrophy
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Increase in heart size due to training
Specifically left ventricle
Thickening of heart muscle
Leads to bradycardia – resting heart rate <60
Cardio-Vascular Drift
• Decreasing venous return
• Decrease in stroke volume
• Heart rate increases
Heart Rate Control
Increase in blood
pressure
Adrenaline
Conduction of
nerve impulses gets
quicker
Increased levels
of carbon
dioxide, lactic
acid
Chemo-receptors
Movement
Baro-receptors
CO2 H+
Muscle
action
Blood pressure
Medulla Oblongata
Vasomotor
Cardiac
Accelerator Centre
Cardiac
Inhibitory
Centre
Centre
Sympathetic
Parasympathetic
Vasoconstriction
or dilation
(Acc nerve)
Vagus nerve
Jan07Q5
Ans
Heart Rate
Control