CV and R Systems

• Pulmonary circuit


  • Carries deoxygenated blood to the lungs and oxygenate blood back to the heart
• Systemic circuit


  • Carries oxygenated blood to the body and deoxygenated blood to the heart
• The path of the blood through the heart

  1. Left side

  2. Right side
• Cardiac systole

  The contraction of the cardiac muscle, firstly of the atria, then the ventricles
• Cardiac diastole

  The relaxation of the cardiac muscle, firstly the atria, then the ventricles
• The Cardiac Cycle


  1. Diastole

  2. Atrial Systole

  3. Ventricular Systole
• Heart Rate


  • An average resting HR is 72 (bpm)
  • HR can be affected by genetics, gender and fitness levels
  • A HR lower than 60 bpm is known as bradycardia
• Maximum Heart Rate


  220 - Age
• Stroke Volume


  • The volume of blood ejected from the left ventricle per beat
  • An average resting SV is 70 ml
• Cardiac Output


  Cardiac Output = Stroke Volume X Heart Rate
• Maximal exercise


  High intensity, anaerobic exercise that will push a performer to exhaustion
• Sub-maximal exercise


  Low - moderate intensity, aerobic exercise
• HR response to exercise


  1. Sub-maximal

  2. Maximal
• SV response to exercise


  • Increased venous return
  • Starling Law
• Respiratory system

  The respiratory system is made up of; the nose, a series of airways, lungs, and respiratory muscles. These all work together as the mechanism for breathing and gaseous exchange.
• Function of the respiratory system

  • Pulmonary ventilation (inspiration and expiration of air)
  • Gaseous exchange
  • External respiration - Movement of O2 into blood and CO2 into the lungs
  • Internal respiration - Release of O2 to respiring cells for energy production & removing waste products
• Structure of the respiratory system

  1. Nasal cavity

  2. Mouth

  3. Bronchus

  4. Bronchioles

  5. Lung

  6. Trachea

  7. Diaphragm

  8. Alveoli
• Air is drawn in through nose to the nasal cavity and travels down the pharynx, larynx and trachea.
• The trachea divides into left and right bronchi as they enter the lung cavity.
• The bronchi divide into smaller bronchioles and end in alveolar ducts.
• The alveolar ducts are the entrance for air to move into the alveoli for gas exchange to take place.
• Oxygen transport


  • 97% - Carried with Haemoglobin in red blood cells
  • 3% - Carried in blood plasma
• Carbon dioxide transport


  • 70% - Dissolved in water
  • 23% - Carried with haemoglobin (carbaminohaemoglobin)
  • 7% - Dissolved in blood plasma
• Breathing rate


  The number of inspirations or expirations taken in one minute
• Tidal volume


  The volume of air inspired or expired in one breath
• Minute ventilation


  The volume of air inspired or expired per minute
• Average breathing rate = 12-15 breaths per minute
• As exercise intensity increases

  Breathing rate increases in proportion until maximum of 50-60 breaths per minute
• During sub-maximal activity

  Breathing rate can plateau, as O2 supply matches O2 demand from muscles
• As exercise intensity increases


  Tidal volume increases initially in proportion up to approx. 3 litres
• During sub-maximal exercise


  Tidal volume can reach a plateau when O2 supply matches O2 demand
• Minute ventilation = Breathing Rate x Tidal Volume
• As exercise intensity increases


  Initial increase in minute ventilation due to adrenaline release before exercise, then rapid increase at start of exercise due to TV and BR increase, followed by steady MV as O2 supply meets O2 demands, and finally initially rapid and then more gradual decrease to resting levels
• Mechanics of breathing


  1. Thoracic cavity

  2. Lungs

  3. Diaphragm

  4. Thoracic cavity

  5. Pulmonary pleura
• Mechanics of inspiration at rest

  External intercostals contract lifting the ribs and sternum up and out

  Diaphragm contracts and flattens

  Lung volume increases, lowering its partial pressure compared to outside the body, so air rushes into the lungs
• Mechanics of inspiration during exercise

  In addition to external intercostals and diaphragm, sternocleidomastoid and pectoralis minor assist in creating a larger contraction, moving the rib cage up and out even further
• Mechanics of expiration at rest


  External intercostals relax, lowering the rib cage and sternum

  Diaphragm relaxes and returns to original 'dome' shape

  Volume inside the lungs decreases, increasing the pressure above pressure outside the body, so air is pushed out of the lungs
• Mechanics of expiration during exercise


  Internal intercostals and rectus abdominis contract, creating a greater down and inwards movement increasing pressure quicker than at rest, so breathing rate is increased
• Muscles


  Movement of ribs and sternum

  Volume of thoracic cavity

  Pressure in lung tissue

  Inspiration (rest)

  Inspiration (exercise)

  Expiration (rest)

  Expiration (exercise)
• Respiratory Control Centre (RCC)


  A control centre in the medulla oblongata responsible for respiratory regulation

  Receives info from nerves and sends messages to change the rate of respiratory muscle contraction

  Has two main centres: The Inspiratory and Expiratory Centres