Cardiovascular System

• Why does the body need a double circulatory system?

  - Pulmonary system provides deoxygenated blood to lungs, where carbon dioxide is expelled into them

  - Systemic system takes oxygenated blood and carries it to rest of the body and CO2 produced is then transferred back into blood to lungs
• Describe structural and/or physiological differences between elite marathon runners and non-elite joggers (6)

  Elite marathon runners:

  - Increased VO2 max

  - Increased myoglobin content

  - More mitochondria

  - More oxidative enzymes

  - Increased stores of useable glucose

  - Cardiac hypertrophy

  - Reduced body-fat%

  - Increased capillary density
• Describe the structures involved in gaseous exchange in the lungs and explain how gaseous exchange occurs within this tissue (6)

  - Gas exchange is the delivery of oxygen from lungs to bloodstream

  - Elimination of CO2 from bloodstream to lungs

  - Occurs between alveoli and capillaries located in walls of alveoli

  - Gaseous exchange depends on partial pressure of each gas

  - Via diffusion

  - High partial pressure to low partial pressure
• Describe how oxygen is transferred from the alveoli to muscle at rest (4)

  - At lungs, diffusion of the oxygen into the capillaries from the alveoli

  - Diffusion occurs from high concentration to low concentration/partial pressure

  - Oxygen binds to haemoglobin

  - Transport of oxygen via cardiovascular system to muscles

  - Oxygen diffuses into muscle from high pp to low pp
• Summarise the functions of three structural components of the cardiovascular system (3)

  Atria: Contract to push blood into ventricles

  Ventricles: Contract to push blood into blood vessels

  Valves: Prevent backflow of blood

  Capillaries: Allow gas exchange

  RBCs: carry oxygen
• What is meant by partial pressure of oxygen?

  Pressure that oxygen exerts within other gases
• Outline the mechanical process of inspiration at rest (4)

  - Contraction of external intercostal muscles

  - Movement of rib cage up and out

  - Contraction/flattening of diaphragm

  - Expands the volume of thoracic cavity

  - Pressure inside lungs decreases and is less than outside of body

  - Air inside lungs decreases as gas moves from higher to lower pressure
• Outline the mechanical process of expiration at rest (4)

  - Relaxation of external intercostal muscles

  - Movement of rib cage down and in

  - Inflation of diaphragm

  - Decreases the volume of thoracic cavity

  - Pressure inside lungs increases and is more than outside of body

  - Air inside lungs increases
• Summarise how oxygen is delivered to the working muscles increase during exercise (4)

  - Increased ventilation/tidal volume

  - Increased diffusion gradient(s)

  - Increased cardiac output/stroke volume/heart rate

  - Increased blood volume

  - Vasodilation to increase blood flow to muscles

  - Vasoconstriction of blood vessels in areas where is it not required
• Inspiration:

  - At rest, external intercostal muscles/diaphragm contracts/flattens

  - During exercise, pectoralis minor contracts

  - During exercise, allows thoracic cavity to increase in size

  
  

  Expiration:

  - At rest, external intercostal muscles/diaphragm relaxes

  - At rest, Passive process

  - During exercise, internal intercostals contract

  - Pulls ribcage down faster to push air out

  - During exercise, becomes a passive process
• Why does tidal volume change by only a small amount during the exercise period? (3)

  - Major respiratory regulator is carbon dioxide

  - Which controls rate of breathing

  - And depth (TV) of breathing

  - And stimulate a bigger increase in breathing rate when compared with tidal volume.
• Define what is meant by the term 'minute ventilation volume'


  Minute ventilation volume is the volume of air inspired or expired in one minute (VE)
• Define the terms:

  a) Functional residual capacity (1)

  b) Total lung capacity (1)

  Functional residual capacity is the amount of air that can fill the lungs

  
  

  Total lung capacity is the maximum amount of air that can fill the lungs
• How is 'breathing rate' controlled to meet the demands of changing levels of exercise? (4)

  - Exercise increases CO2 levels

  - Increases acidity

  - Detected by chemoreceptors

  - Nerve impulse to respiratory centre

  - Phrenic nerve
• Define the term vital capacity (1)

  Maximum volume forcefully expired after maximal inspiration
• Outline the change in four respiratory values during aerobic exercise (4)

  Tidal volume: increase

  
  

  IRV: decrease

  
  

  ERV: decrease

  
  

  Vital capacity: decrease
• Explain the meaning of Q=SVxHR and give typical resting values that you would expect in an endurance based athlete (6)

  Q = Cardiac output (volume of blood pumped by left ventricle in one minute

  - Combination of stroke volume and heart rate

  - Typical resting values are 5.6 l/m-1 = 110ml x 51
• How is blood flow to various regions of the body controlled? (4)

  - Achieved through vasomotor control

  - Which creates the vascular shunt

  - This is vasodilation, which is expansion of arteries and arterioles

  - This is in response to cessation of neural signals to smooth muscle walls of vessels

  - Vasoconstriction restricts arteries and arterioles

  - In response to increased neural signals from baroreceptors which detect changes in cardiac output
• What is meant by venous return mechanism (2)

  Venous return is the transport of blood from the capillaries, through venules, veins and venae cavae to the right atrium of the heart.
• Describe how venous return is aided during physical activity when a person is exercising in an upright condition (3)

  - Venous return is aided by exercise due to increased actions of skeletal muscle and respiratory and cardiac pumps and limited action of venoconstriction of veins.

  - Increased activity in skeletal muscle results from contracting and relaxing squeezing sections of veins.

  - Therefore causing increased blood flow back towards the heart.
• Explain the importance of the skeletal muscle pump mechanism during an active cool down (2)

  - Skeletal muscles continue to contract to squeeze vein walls, forcing blood back towards the heart.

  - Thereby preventing blood pooling and an associated sudden drop in blood pressure.

  - And removing of waste products such as carbon dioxide and lactic acid.
• What effect does enhanced venous return have upon cardiac output and stroke volume? (3)

  - Stroke volume is dependent on the amount of venous return

  - Increased venous return will cause myocardial tissue to be stretched even further.

  - And so contract more forcibly

  - To increase stroke volume
• Identify one factor that affects resistance to the flow of blood within systemic blood vessels (1)

  - Friction between moving blood and the walls of blood vessels.

  - Length of blood vessels.

  - Diameter or lumen width of blood vessels.

  - Viscosity of blood.
• What does mm/Hg refer to?

  'mm' is the systolic pressure when ventricles contract

  
  

  'Hg' is the diastolic pressure when ventricles relax
• How would blood pressure values change during a game of football and a rugby scrum lasting 6 seconds with reason to your answer (3)


  FOOTBALL:

  - Dynamic exercise so systolic pressure would rise

  - Because of increased cardiac output

  - Diastolic pressure remains same as resting value

  
  

  RUGBY SCRUM:

  - Raises both pressures

  - Because isometric position reduced actions of skeletal muscle and resp' pumps

  - Which reduces venous return, cardiac output, blood pressure and capillary blood flow
• Describe how running affects venous return mechanism (3)

  - Venous return increases

  - Skeletal pump increases muscle contractions and pushes blood towards heart

  - One way valves in veins to prevent backflow

  - Respiratory pump allows greater breathing movements which alter pressure in thorax
• How is carbon dioxide transported in the blood (2)

  - As hydrogen carbonate ions/bicarbonate ions/combines with water/carbonic acid

  - Combined with haemoglobin/carbaminohaemoglobin

  - Dissolved in plasma
• Explain one reason why vascular shunting is necessary during a game of basketball (3)

  - Necessary to transport oxygen to muscles as they require more oxygen to work aerobically

  - Muscles require nutrients for energy which prevents fatigue

  - Muscles require removal of CO2 which means they can maintain quality of performance
• Identify two effects of regular aerobic training on lung volumes and capacities. (2)

  - Improved strength of respiratory muscles

  - Increase in TV, VC at expense of RV

  - At submax. workloads slightly decrease in frequency of breaths

  - At max. workloads increase in frequency of breaths
• Explain why heart rate takes some time to return to its resting value following the exercise period. (2)

  - Raised levels of O2 and CO2

  - Build up of lactic acid during high intensity work which takes time to clear

  - Heart needs more O2 than resting O2 consumption
• Identify a hormone that is responsible for heart rate increases prior to and during an exercise period (1)

  - Adrenaline

  - Noradrenaline
• Heart rate is regulated by neural, hormonal and intrinsic factors. How does the nervous system detect and respond to changes in heart rate during an exercise period? (4)

  - CCC responds to neural information

  - Supplied by proprioceptors

  - Baroreceptor reflex is sensitive to changed in Bp

  - Chemoreceptor is sensitive to changes in CO2 and pH levels

  - Acceleration nerve increases stimulation of SA node

  - Increasing heart rate
• An unhealthy lifestyle is likely to lead to risky behaviours. Describe how smoking adversely affects the respiratory system. (6)

  - Sticky mucus in lungs traps pathogens which normally are swept out by cilia cells

  - However, smoking damages these which leads to a build up of mucus

  - Smoke irritates bronchi and can cause bronchitis

  - Reduces efficiency of gas exchange so people with COPD find mild exercise difficult

  - Carcinogens cause cancer which is found in tar which is an ingredient in cigarettes
• Identify three healthy lifestyle changes to reduce diabetes risk. (3)

  - Engage in 30 to 60 mins or more of daily exercise.

  - Keep alcohol consumption at the light to moderate level.

  - Consume a healthy diet.

  - Maintain a body mass index (BMI) of less than 25.
• Describe the effects of an unhealthy lifestyle on the cardiovascular system. (4)

  - Stiffening of blood vessels

  - Blocking of blood vessels

  - Reduction in blood flow

  - Increase in blood pressure

  - Increase in stroke volume

  - Heart has to contract more to deliver same amount of blood