1. Antrim PE Revision Course AQA AS PHED 1
Session 3b
Applied Physiology – Respiration & Cardiac Function

2. Respiration – need to know
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

3. Cardiac function – need to know
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

4. Breathing Quiet breathing – diaphragm+ intercostals
Deep breathing – sternocleidomastoid + pectorals

5. Autonomic breathing control
Chemo-receptors
CO2
Inflation of aleveoli
Medulla Oblongata
Respiratory
Accelerator Centre
Respiratory Inhibitory Centre
Parasympathetic
Vagus nerve
Sympathetic
(Acc nerve)
The role of the brain in breathing
Normal relaxed rhythmical breathing is controlled unconsciously by the medulla oblongata of the brain.
A rise in blood CO2 stimulates the medulla to fire, sending nerve impulses to the breathing muscles.
The diaphragm and intercostal muscles contract and so air is breathed in.
Inflation of the alveoli causes nerve feedback to the medulla switching off its stimulation of the breathing muscles.
Breathing in stops and the lungs recoil causing expiration.
The cerebellum allows us to voluntarily control our breathing if desired, e.g., talking, singing and laughing
Autonomic breathing control
Lungs
Intercostal muscles
Diaphragm Contract

6. Respiration – Lung Volumes
June02Q3
Ans

7. Respiration - Ventilation
Ventilation = Tidal Volume x Frequency (breathing rate)
Frequency/Breathing rate:
Resting min-1 Peak: min-1
Tidal volume:
Resting 0.5L Peak: 2.25 L
Minute Ventilation
Resting: 6 lt/min Peak:175 lt/min-1

8. Respiration - O2 Transport
Red Blood Cells
Haemoglobin > Oxyhaemoglobin
From alveoli – to muscle cell boundary
Myoglobin > Oxymyoglobin
From muscle cell boundary > mitochondria
Carbon dioxide
70-80% Bicarbonate carbonic acid HCO3
5-10% Dissolved in plasma
5-10% Carbaminohaemoglobin
A-V difference

9. Arterial – Venous Oxygen Difference (a-VO2 diff)
Arterial Blood
O2%
Venous Blood
a-VO2 Diff
More oxygen is extracted by working muscles
Rest 20 15 5
Intense Exercise 20 5 15
Jun02Q5
Ans

10. Blood Flow in Capillary
CO2
Gas
Exchange
Alveolus
PCO2 40mm Hg
PO2 104mm Hg
Capillary
PCO2 45mm Hg
PCO2 40mm Hg
PO2 40mm Hg
PO2 104mm Hg
Blood Flow in Capillary

11. Exercise and oxygen disassociation
Rise in temperature
Acidity rise due to CO2 LA increase
Curve moves to the right
Jun02Q5
Haemoglobin disassociates oxygen more readily
More O2 available during exercise
Ans

12. Pulmonary and systematic circulation
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.

13. Invisible on this scale
Blood vessels
Invisible on this scale
Arterioles
Venules
Arteries - thick muscular walls; take blood away from heart - high pressure; elastic
Capillaries - tiny, very thin walls - diffusion of substances in and out
Veins - thin walled; carry blood back to heart - need help - venous return

14. 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

15. Dynamics of venous return
Muscle pump
Respiratory pump

16. Blood pressure and velocity
Arteries
Veins
Venules
Capillaries
Arterioles
Velocity falls and rises – with increasing & decreasing total cross-sectional area
Blood pressure
Blood velocity
Pressure falls - friction & increasing cross-sectional area
Total cross-sectional area
Jun04Q5
Ans

17. Starlings Law Increase in fibre length Increase in contractility
Trained heart will contract more powerfully SV
Trained Heart
Normal contractility
Left ventricle
Venous return
Increased venous return
Increased filling of left ventricle
Increase in fibre length
Increase in contractility
Increased stroke volume

18. Blood Flow - Redistribution
Ans
Jan04Q1
Blood Flow in cm3 per minute
Area
Rest
Max
Muscles
1000
26000
Heart
250
1200
Skin
500
750
Kidneys
300
Liver & Gut
1250
375
Brain
Whole
5000
30000
Liver & Gut
Rest
Liver & Gut
Max Exercise

19. Blood Flow Redistribution - Volume
Blood Flow in cm3 per minute
Increase to skeletal muscles & heart
Area
Rest
Max Ex
Muscles
1000
26000
Heart
250
1200
Skin
500
750
Kidneys
300
Liver & Gut
1250
375
Brain
Whole
5000
30000
Decrease to liver, gut, kidneys
Brain stays same
Increase in total blood flow (Cardiac Output)
SV+ HR+

20. Cardiac cycle Contraction = systole The order of contraction Diastole
Relaxation = diastole
Atrial systole
High pressure (systole) in chambers forces valves open
Ventricular systole
Valves close when pressure drops again (diastole)

21. 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)
With a partner trace the route of the blood flow through the heart and the body.
You should include the following terms:
left atria, right atria, left ventricle, right ventricle, vena cavae, aorta, pulmonary vein, pulmonary artery, mitral valve, tricuspid valve, semi-lunar valves (aortic and pulmonary), lungs, body.

22. Cardiac Hypertrophy Cardio-Vascular Drift
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

23. Heart Rate Control Increase in blood pressure Adrenaline
Conduction of nerve impulses gets quicker
Increased levels of carbon dioxide, lactic acid

24. Medulla Oblongata Heart Rate Control Chemo-receptors CO2 H+ Movement
Muscle action
Baro-receptors
Blood pressure
Medulla Oblongata
Cardiac Accelerator Centre
Cardiac Inhibitory Centre
Vaso-motor
Centre
Parasympathetic
Vagus nerve
Sympathetic
(Acc nerve)
Vaso-constriction or dilation
Heart Rate Control
Jan07Q5
Ans