Anatomy and Physiology

• Stroke volume is the volume of blood pumped out of the left ventricle with each contraction
• Heart rate is the number of times the heart beats per minute. It is controlled by the autonomic nervous system.
• Cardiac output is the volume of blood pumped out of the heart per minute. Q=SV x HR
• Cardiac conduction system

  1. Electrical signal at the SAN (sinoatrial node)
  2. The electrical impulse spreads through the atria walls causing them to contract, impulse passes through the AVN (atrioventricular node) where there is a 0.1 second delay
  3. Impulse passes through the bundle of HIS, which divides into two branches called Purkinje fibres - this spreads the impulse through the ventricles
• chemoreceptors detect increase in blood pressure -> cardiac control centre -> sympathetic nervous system -> SAN increase heart rate
• baroreceptors detect increase in blood pressure -> cardiac control centre -> parasympathetic nervous system -> SAN decrease in heart rate
• proprioceptors detect increase in muscle movement -> cardiac control centre -> sympathetic nervous system -> SAN increases heart rate
• Veins - thinner muscle/elastic tissue layers, blood is at low pressure, valves present and a wider lumen
• Arteries - experience the highest pressure, a narrower lumen and a smooth inner layer
• Capillaries - one cell thick, short diffusion pathway, large surface area and a narrow diameter
• Venous return mechanisms:

  • the skeletal muscle pump - when muscles contract and relax they press on nearby veins, this causes a pumping effect and squeezing the blood towards the heart
  • the respiratory pump - when muscles contract and relax during the inspiration and expiration process, pressure changes in the thoracic and abdominal cavities.
  • valves - prevent the backflow of blood
  • thin layer of smooth muscle within the veins helps squeeze blood back towards the heart
  • gravity helps the blood return to the heart from the upper body
• Pre-capillary sphincters also aid blood redistribution, they are located at the openings of capillaries
• Why is the redistribution of blood important?

  • increases the supply of oxygen to working muscles
  • remove waste products from the muscles
  • ensure that more blood goes to the skin during exercise
  • direct more blood to the heart
• What is arterio-venous oxygen difference?

  The difference in oxygen content between arterial and venous blood.
• What is tidal volume?

  The volume of air inhaled or exhaled during normal breathing.
• What is the inspiratory reserve volume?

  The maximum amount of air that can be inhaled after a normal inhalation.
• What is expiratory reserve volume?

  The maximum amount of air that can be exhaled after a normal exhalation.
• What is the residual volume?

  The volume of air remaining in the lungs after maximum exhalation.
• What is minute ventilation?

  Minute ventilation is the total volume of air breathed in and out in one minute.
• Why is the structure of the alveoli important?

  • thin walls create a short diffusion pathway
  • extensive capillary network surrounding the alveoli
  • a huge surface area
• What are proprioceptors?

  Sensory receptors that provide information about body position and movement.
• What are baroreceptors?

  Sensory receptors that detect changes in blood pressure.
• What can smoking cause?

  • irritation of the trachea and bronchi
  • reduced lung function and increased breathlessness
  • damage cells lining the airway
  • reduction in the efficiency of gaseous exchange
• What is the role of the sympathetic nervous system?

  Fight or flight response as well as preparing the body for exercise
• What is the role of the parasympathetic nervous system?

  Rest and digest, as well as slowing down high-energy functions
• What are muscle spindles?

  They are proprioceptors that send excitory signals to the CNS about how far and a fast a muscle is being stretched. The CNS then sends impulses to the muscle causing it to contract and produce the stretch reflex.
• What are golgi tendon organs?

  Detect levels of tension in a muscle, when the muscle is contracted isometrically in proprioceptive neuromuscular facilitation they sense the increase and send inhibitory signals to the brain. This allows the antagonist muscle to relax and lengthen (known as autogenic inhibition).
• Sports injuries include various types of injuries such as acute injuries, chronic injuries, fractures, dislocations, sprains, and strains.
• Common injuries associated with a sport are often synonymous with the sport itself and can be either chronic or acute.
• Acute injuries are characterized by sudden, severe pain, swelling around the injured site, inability to bear weight, restricted movement, extreme weakness, and a joint or bone that is visibly out of place.
• Fractures are breaks or cracks in a bone.
• Comminuted fractures are where the bone breaks in three or more places.
• Spiral fractures are winding breaks created by torsion or twisting forces.
• Longitudinal fractures occur along the length of a bone.
• Buckle fractures usually occur in children when the bone deforms but doesn’t break.
• Hairline fractures are partial fractures that are difficult to detect.
• Greenstick fractures usually occur in children with a partial break.
• The greater the mass of the performer, the more stability there is due to an increase in inertia.
• The mass of the performer affects the stability of the performance.
• Stable fractures are fractures that do not involve a displacement of the bone.