Diffusion is the net movement of gas molecules from an area of high partial pressure to an area of low partial pressure.

What is external respiration?

External respiration is gas exchange between the alveoli and the blood in the pulmonary capillaries.

What is internal respiration?

Internal respiration is gas exchange between the blood in the tissue capillaries and the muscle cells.

Why does oxygen diffuse from the alveoli into the blood?

The partial pressure of oxygen in the alveoli is about 100 mmHg, against about 40 mmHg in the returning blood. Oxygen diffuses down this gradient into the blood.

Why does carbon dioxide diffuse from the blood into the alveoli?

Blood arriving at the lungs has a carbon dioxide partial pressure of about 45 mmHg, against about 40 mmHg in the alveoli. Carbon dioxide diffuses down the gradient into the alveoli.

Edexcel A-Level Physical Education 9PE0

The Musculo-Skeletal System

Topic overview Muscles, bones and movements of the upper body Muscles, bones and movements of the lower body and trunk Contraction types and the stretch-shortening cycle Muscle roles and the acute response to a warm-up

Levers, Newton's Laws and Stability

Topic overview Lever systems in the body Mechanical advantage and disadvantage of levers Newton's laws of motion and force calculations Centre of mass and stability

The Respiratory System

Topic overview Structure of the airways and alveoli The mechanics of breathing Gas exchange, partial pressure and diffusion Lung volumes and capacities

The Cardiovascular System

Topic overview Heart structure and the conduction system Blood vessels, circulation and vascular shunting Heart rate, cardiac output and bradycardia Exercise responses and the effects of an unhealthy lifestyle

The Neuromuscular System

Topic overview Muscle fibre types and their characteristics Motor units, recruitment and gradation of contraction Muscle structure and the sliding filament theory Neuromuscular transmission and the response to warming up

Adaptations to Training

Topic overview Heart and lung adaptations to training Muscle and bone adaptations to training Nervous system and muscle fibre adaptations

Energy Systems

Topic overview Forms of energy and ATP The ATP-PC and glycolytic systems The aerobic system and fuel use The energy continuum and priming exercise

Fatigue and Recovery

Topic overview Fatigue from energy depletion and dehydration Lactic acid, hydrogen ions and fatigue Oxygen deficit, EPOC and the fast component The slow component and recovery windows

Diet, Nutrition and Supplements

Topic overview Energy balance, nutrients and optimal weight Hydration, electrolytes and sports drinks Legal supplements and their effects Carbohydrate loading and fuelling around exercise

Fitness Testing

Topic overview Gas analysis and aerobic field tests Lactate and functional threshold testing Anaerobic capacity and power tests Strength, agility and sprint tests

Components and Principles of Training

Topic overview Aerobic, anaerobic and muscular fitness Speed, agility, balance and coordination Principles of training and FITT Measuring intensity, Karvonen and monitoring technology

Training Methods and Periodisation

Topic overview Periodisation cycles and recovery strategies Continuous, fartlek, interval, circuit and cross training Flexibility, resistance, plyometric and SAQ training Training at altitude and in heat and humidity

Injury Prevention and Rehabilitation

Topic overview Classifying injuries and acute injuries Overuse injuries: shin splints, tendonitis and stress fractures Preventing sports injuries Rehabilitation methods, POLICE and RICE

Linear and Angular Motion

Topic overview Distance, displacement, speed and acceleration Distance–time, speed–time and velocity–time graphs Angular motion and moment of inertia Conservation of angular momentum

Projectile Motion and Fluid Mechanics

Topic overview Forces acting on a projectile in flight Release velocity, height and angle Drag, streamlining and technology Lift, the Bernoulli effect and spin

Coaching and Skill Classification

Topic overview Mosston's coaching styles Tactics and strategies in competition Analysing a skill in phases Classifying skills on continuums Transfer of skills

Learning Theories

Topic overview Classical and operant conditioning Reinforcement, punishment and the S-R bond Thorndike's laws of learning Fitts and Posner's stages of learning

Practice and Guidance

Topic overview Whole, part, progressive part and whole-part-whole practice Massed, distributed, fixed and variable practice Visual, verbal, manual and mechanical guidance Technology in guidance

Feedback and Motor Control

Topic overview Purposes and effectiveness of feedback Types of feedback Feedback technology and performance analysis Open and closed loop control

Information Processing and Memory

Topic overview Welford and Whiting's information processing models The sensory store and short-term memory Long-term memory and the multi-store model Reaction time, Hick's law and the psychological refractory period Schmidt's schema theory

Personality and Attitudes

Topic overview Sport psychology and the nature–nurture debate Trait theory: Eysenck and Cattell Interactionist theory and personality structure Attitudes, Wood's triadic model and cognitive dissonance

Arousal and Anxiety

Topic overview Arousal and the optimal level for performance Drive, inverted-U and catastrophe theories Anxiety, stress and stressors Cognitive and somatic stress management strategies

Aggression

Topic overview Aggression and assertion in sport Types of aggression Theories of aggression: Lorenz, Bandura, Dollard and Berkowitz Causes of aggression and strategies to reduce it

Motivation

Topic overview Types of motivation Internal, external, tangible and intangible rewards Achievement motivation: NACH and NAF Developing a need to achieve

Social Facilitation

Topic overview Social facilitation, social inhibition and types of others Zajonc's dominant response and evaluation apprehension Home advantage, distraction, proximity and coping with an audience

Group Dynamics and Cohesion

Topic overview Groups, teams, and task and social cohesion Carron's four factors of cohesion Steiner's model and the Ringelmann effect Social loafing and building team cohesion

Goal Setting

Topic overview SMARTER targets Outcome, performance and process goals Goal timescales and the benefits of goal setting

Attribution Theory

Topic overview Weiner's attributions for success and failure The three dimensions of attribution Attribution retraining

Confidence and Self-Efficacy

Topic overview Self-confidence and its effect on performance Vealey's model of sport confidence Bandura's four sources of self-efficacy Learned helplessness

Leadership

Topic overview Qualities and impact of an effective leader Autocratic, democratic and laissez-faire styles Fiedler's and Chelladurai's leadership models Trait, social learning and interactionist theories of leadership

The Emergence of Modern Sport

Topic overview Popular recreation in pre-industrial Britain The Industrial Revolution and recreation Rational recreation, Arnold and athleticism Factory teams, the sporting press and the first governing bodies

Equality, Diversity and Migration in Sport

Topic overview Corporate and geographically based teams Disability sport and opportunities for women Migration of sporting labour

The Globalisation of Sport

Topic overview What globalisation means for sport Colonial diffusion of sport across the British Empire National and international governing bodies Bidding for and staging world events

The Commercialisation of Sport

Topic overview Commercialisation and sport as a commodity Broken time, spectatorism and the media The Olympic Games and the 1984 commercial blueprint Franchises, Americanisation and global stars

Ethics and Deviance in Sport

Topic overview Ethics, sportsmanship and gamesmanship Performance-enhancing drugs from early use to today Simulation, bribery, bungs and match fixing Responses to deviance and the role of WADA

Sport and the Media

Topic overview The two-way relationship between sport and the media Live and social media coverage Viewing technology, sports packages and pay-per-view

Talent Identification and Elite Development

Topic overview Talent identification programmes in the UK The pathway from novice to elite performer East German and Australian influences on UK sport

Participation and the Health of the Nation

Topic overview Barriers to participation and the benefits of mass participation Mass participation initiatives in the UK Participation trends in the 21st century

The Respiratory System

Gas exchange, partial pressure and diffusion

3 things to know
Component 1

Overview

Partial pressure and diffusion, external and internal respiration, oxygen and carbon dioxide gradients at the alveoli and the muscles, how each gas is carried, the oxyhaemoglobin dissociation curve, the Bohr shift and the a-vO₂ difference.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Where do external and internal respiration take place, and why does oxygen enter the blood at the lungs?

Key term

What is partial pressure?

Key term

Define diffusion.

Questions from this subtopic

Each one with the model answer underneath.

1
What is partial pressure?
Model answer
Partial pressure is the pressure one gas exerts within a mixture of gases. Each gas diffuses from where its partial pressure is high to where it is low.
2
Define diffusion.
Model answer
Diffusion is the net movement of gas molecules from an area of high partial pressure to an area of low partial pressure.
3
What is external respiration?
Model answer
External respiration is gas exchange between the alveoli and the blood in the pulmonary capillaries.
4
What is internal respiration?
Model answer
Internal respiration is gas exchange between the blood in the tissue capillaries and the muscle cells.
5
Why does oxygen diffuse from the alveoli into the blood?
Model answer
The partial pressure of oxygen in the alveoli is about 100 mmHg, against about 40 mmHg in the returning blood. Oxygen diffuses down this gradient into the blood.
6
Why does carbon dioxide diffuse from the blood into the alveoli?
Model answer
Blood arriving at the lungs has a carbon dioxide partial pressure of about 45 mmHg, against about 40 mmHg in the alveoli. Carbon dioxide diffuses down the gradient into the alveoli.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

The Musculo-Skeletal System

Levers, Newton's Laws and Stability

The Respiratory System

The Cardiovascular System

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

The survey began in .

201520052012

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe training zone is 136 to 158 bpm.

BHeart rate reserve = (220 − 40) − 70 = 110 bpm.

CLower limit = (110 × 0.6) + 70 = 136 bpm.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Acceleration means a rise in velocity each second.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in The Respiratory System, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.