What is a diffusion gradient?

A diffusion gradient is the difference in partial pressure of a gas between two areas. The steeper the gradient, the faster the gas diffuses.

Explain how oxygen moves from the alveoli into the blood.

The partial pressure of oxygen in the alveoli is higher than in the capillary blood arriving at the lungs. Oxygen diffuses down this gradient into the blood.

Give typical partial pressures of oxygen in the alveoli and in blood arriving at the lungs.

Alveolar air has a partial pressure of oxygen of about 100 mmHg. Deoxygenated blood arriving at the lungs has about 40 mmHg.

What is the oxygen diffusion gradient between alveolar air at 100 mmHg and capillary blood at 40 mmHg?

The diffusion gradient is 60 mmHg. The gradient = 100 mmHg − 40 mmHg = 60 mmHg.

AQA A-Level Physical Education 7582

The Cardiovascular System

Topic overview Heart health, fitness and cardiac output The cardiac conduction system and heart rate control Receptors, vascular shunting and blood redistribution Oxygen transport, the Bohr shift and the a-VO₂ difference Venous return, Starling's law and cardiovascular drift

The Respiratory System

Topic overview Lung volumes and minute ventilation Gas exchange, diffusion and partial pressure Control of breathing during exercise Smoking and the respiratory system

The Neuromuscular System

Topic overview Muscle fibre types and their characteristics The nervous system and motor units Summation, the all-or-none law and tetanic contraction Muscle spindles, Golgi tendon organs and PNF

The Musculo-Skeletal System and Movement Analysis

Topic overview Planes, axes and sagittal plane joint actions Frontal and transverse plane joint actions Joint types, articulating bones and muscle pairs Isotonic and isometric contraction in sporting actions

Energy Systems

Topic overview ATP and the aerobic energy system Anaerobic energy systems and the energy continuum Lactate accumulation, the lactate threshold and OBLA Oxygen deficit and EPOC VO₂ max, RER and measuring energy expenditure Altitude training, HIIT, plyometrics and SAQ

Skill, Transfer and Practice

Topic overview Characteristics of skill Classifying skills on the six continua Transfer of learning Whole, progressive part and whole–part–whole practice Massed, distributed, variable and mental practice

Theories of Learning

Topic overview Fitts and Posner's stages of learning Learning plateaus and performance curves Insight learning and operant conditioning Observational learning and social development theory

Guidance and Feedback

Topic overview Verbal and visual guidance Manual and mechanical guidance Types of feedback Matching feedback and guidance to the learner

Information Processing and Memory

Topic overview Input, receptors and the DCR process Memory and the working memory model Whiting's information processing model Reaction time, response time and Hick's law The psychological refractory period and anticipation Schmidt's schema theory

The Emergence and Globalisation of Sport

Topic overview Pre-industrial society, mob football and real tennis Industrialisation, urbanisation and rational recreation Association football, lawn tennis and Victorian athletics Amateurs, professionals and women in Victorian sport The Golden Triangle of sport, media and sponsorship Professionalism and elite women's sport since 1950

Equal Opportunities in Sport

Topic overview Society, socialisation and social structures Social action theory, prejudice and stereotyping Barriers and solutions for women and ethnic minority groups Barriers and solutions for disabled and disadvantaged groups Benefits of participation, Sport England and its partners

Diet and Nutrition

Topic overview Carbohydrate, fibre and fats for exercise Protein, vitamins and minerals Hydration before, during and after exercise Creatine, sodium bicarbonate, caffeine and glycogen loading

Preparation and Training Methods

Topic overview Fitness testing: data, validity and reliability Warm-up, cool-down and stretching Principles of training and FITT Periodisation, tapering and peaking Training methods for fitness and health

Injury Prevention and Rehabilitation

Topic overview Acute and chronic sports injuries Screening, protective equipment, flexibility and taping Rehabilitation methods and their physiological basis Recovery methods, sleep and nutrition

Biomechanical Principles and Levers

Topic overview Newton's laws of linear motion Speed, distance and scalar quantities Centre of mass and stability Lever classes and mechanical advantage

Linear and Angular Motion

Topic overview Forces acting in linear motion Vectors: displacement, velocity, acceleration and momentum Impulse and force–time graphs in sprinting Angular motion and conservation of angular momentum

Projectile Motion and Fluid Mechanics

Topic overview Factors affecting horizontal displacement Flight paths and vector components of projectiles Drag and dynamic fluid force Lift and the Bernoulli principle

Personality and Attitudes

Topic overview Trait and social learning theories of personality The interactionist perspective in sport The triadic model and how attitudes form Changing attitudes: cognitive dissonance and persuasive communication

Arousal and Anxiety

Topic overview Drive theory and the inverted-U Catastrophe theory, the zone of optimal functioning and peak flow Somatic, cognitive, trait and state anxiety Measuring anxiety

Aggression

Topic overview Aggression and assertive behaviour Theories of aggression Strategies to control aggression

Motivation and Achievement Motivation

Topic overview Intrinsic and extrinsic motivation Atkinson's model: need to achieve and need to avoid failure Incentive value and probability of success Achievement goal theory and approach behaviour

Social Facilitation and Group Dynamics

Topic overview Zajonc's model of social facilitation Evaluation apprehension and coping with an audience Tuckman's model and team cohesion Steiner's model, the Ringelmann effect and social loafing

Goal Setting

Topic overview Outcome, performance and process goals Why goal setting works SMARTER goal setting

Attribution Theory

Topic overview The attribution process and Weiner's model Attribution, task persistence and self-serving bias Learned helplessness, general and specific Attribution retraining and overcoming helplessness

Self-Efficacy and Confidence

Topic overview Self-efficacy, self-confidence and self-esteem Bandura's model of self-efficacy Vealey's model of sport confidence Home field advantage and building self-efficacy

Leadership

Topic overview Effective, prescribed and emergent leaders Autocratic, democratic and laissez-faire styles Fiedler's contingency theory Chelladurai's multi-dimensional model

Stress Management

Topic overview Stress, stressors and the warm-up Mental rehearsal, visualisation and imagery Attentional control, thought stopping and self-talk Somatic relaxation techniques

Concepts of Physical Activity and Sport

Topic overview Physical recreation and sport Physical education and school sport The sports development continuum

Development of Elite Performers

Topic overview Talent identification and progression factors National governing bodies, national institutes and UK Sport Support services for talent development World Class Programme and UK Sport talent schemes

Ethics and Violence in Sport

Topic overview Amateurism, sportsmanship and the win ethic Positive and negative deviance Causes and implications of violence in sport Preventing violence among performers and spectators

Drugs in Sport

Topic overview Why elite performers use drugs EPO, anabolic steroids and beta blockers Consequences of drug taking for sport and performer Eliminating drugs and the testing debate

Sport, the Law and Commercialisation

Topic overview The law and the sports performer Negligence, duty of care and spectator law Commercialisation, the performer and the coach Commercialisation, officials, audiences and the sport

Technology in Sport

Topic overview Collecting and analysing sports data Functions of sports analytics Sports equipment and facilities Benefits and drawbacks of sports technology

The Respiratory System

Gas exchange, diffusion and partial pressure

3 things to know
Paper 1

Overview

Diffusion, partial pressure and diffusion gradients, gas exchange at the alveoli and at the muscles, typical partial pressures, alveolar features and the effect of training.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What are the partial pressures of oxygen in alveolar air and in blood arriving at the lungs, and what gradient results?

Key term

Define diffusion as it applies to gas exchange.

Key term

What is partial pressure?

Questions from this subtopic

Each one with the model answer underneath.

1
Define diffusion as it applies to gas exchange.
Model answer
Diffusion is the movement of gas molecules from an area of high partial pressure to an area of low partial pressure.
2
What is partial pressure?
Model answer
Partial pressure is the pressure exerted by one gas within a mixture of gases.
3
What is a diffusion gradient?
Model answer
A diffusion gradient is the difference in partial pressure of a gas between two areas. The steeper the gradient, the faster the gas diffuses.
4
Explain how oxygen moves from the alveoli into the blood.
Model answer
The partial pressure of oxygen in the alveoli is higher than in the capillary blood arriving at the lungs. Oxygen diffuses down this gradient into the blood.
5
Give typical partial pressures of oxygen in the alveoli and in blood arriving at the lungs.
Model answer
Alveolar air has a partial pressure of oxygen of about 100 mmHg. Deoxygenated blood arriving at the lungs has about 40 mmHg.
6
What is the oxygen diffusion gradient between alveolar air at 100 mmHg and capillary blood at 40 mmHg?
Model answer
The diffusion gradient is 60 mmHg. The gradient = 100 mmHg − 40 mmHg = 60 mmHg.

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