Cardiovascular system

Stroke Volume:
1. Volume of blood pumped out of the left ventricle per beat
2. Venous return- Volume of blood returning to the heart via veins. Increased venous return, stroke volume increases. (More blood goes in, more blood goes out)
  1. Elasticity of fibres: diastole phase- when the heart relaxes to fill with blood. More fibres stretch, greater force of contraction.
    1. Ejection Fraction- % of blood pumped out by the left ventricle per beat.
      1. Starlings law: increased venous return, greater diastolic filling, cardiac muscles stretched, force of contraction & Increased ejection fraction
4 chambers of the heart: Separated by septum, Ventricles-thicker muscle. Atriums- Thinner muscle
Myogenic- Generates its own impulses
Blood vessels:
1. Vena cava- deoxygenated blood back to the right atrium
  1. Pulmonary Artery- deoxygenated blood to the lungs
    1. Pulmonary vein- oxygenated blood to left atrium
      1. Aorta- oxygenated blood to the rest of the body
Valves:
1. Tricuspid valve- right atrium & right ventricle
  1. Bicuspid valve- Left atrium & left. ventricle
    1. Semi-lunar valve- right atrium & left ventricle, Pulmonary artery & aorta
Cardiac conduction system:
1. Sino atrial node(SA node)- Pacemaker
  1. Electrical impulse-(Wave of excitation)
    1. Atrioventricular node(AV node)- Delays for 0.1 secs before ventricular systole
      1. Bundle of his- transmit implies via bundle branches to the ventricles
        Purkinje fibres- Conduct impulses in the walls of ventricles
2. Factors affecting Rate:Means heart rate increase during exercise so working muscles get 02.
  1. Neural control mechanisms:
    1. Parasympathetic : Returns heart to resting
      1. Sympathetic: Stimulates heart to beat faster
        CNS- Brain & spinal cord
        Medulla oblongata- regulates brain processes. I.E) Breathing rate and heart rate
    2. PNS- Sympathetic and Parasympathetic
  2. Chemoreceptors: Chemical changes, Increase in C02- important for heart rate
    1. Increase blood C02, Increase in heart rate.
  3. Baroreceptors: Detects change in blood pressure
    1. Increase blood pressure, decrease heart rate
  4. Proprioceptors: detects changes in muscle movement
    1. More movement, impulse to medusa oblongata, sympathetic nervous system to increase heart. Parasympathetic stimulates SAN, decreasing heart rate.
  5. Hormonal control: Adrenaline- Stress hormone released by the sympathetic nervous system to increase heart rate. Stimulates SAN, increasing cardiac output- more blood pumped, more 02
    1. Anticipatory rise
Cardiac output:
1. Volume of blood pumped out of the left ventricle per minute
2. Stroke volume X Heart rate
3. Max heart rate = 220- Age
  1. Trained performer has a greater heart rate range & resting heart rate is lower
  2. Average resting heart rate = 72 bpm
    1. Cardiac hypertrophy- Thickening of the muscular wall of the heart so its bigger & stronger- Larger ventricular cavity. Aerobic training. Effects stroke volume, heart rate & cardiac output. End diastolic volume of the ventricle increases.
      1. Bradycardia- Resting heart rate decreases below 60 bpm. Resting heart rate will decrease, as larger contractions mean more blood is forced out during a single contraction.
Impact of Sport on health:
1. Heart disease:
  1. Coronary heart disease(CHD)- Coronary arteries become blocked or or start to narrow because of a build up of fatty-acid deposits(Atheroma),Process= Atherosclerosis
    1. Causes- High blood pressure, high cholesterol levels, smoking, lack of exercise.
    2. Angina- chest pain that occurs when the blood supply through the coronary arteries is restricted.
      1. Blood clot can form if a bit of atheroma breaks off in the coronary artery, causing a blockage cutting off the blood supply to the heart, resulting in a heart attack.
        Regular exercise keeps the heart healthy- Pump more blood around the body as its stronger increasing stroke volume & also maintains flexibility of blood vessels ensuring good blood flow and normal blood pressure.
        2hrs 30mins per week of moderate exercise
2. High blood pressure:
  1. Force exerted by the blood against the blood vessel wall
    1. High blood pressure puts strain on arteries and heart
      1. Risk of heart attack, heart failure, kidney disease, stroke or dementia
        Exercise lowers both systolic and diastolic pressure by up to 5-10 mmHg- reduces heart attack risk by up to 20%.
3. Cholesterol levels:
  1. LDL(Low density lipoproteins)- Transport cholesterol in the blood to the tissues.(BAD cholesterol- linked to increased risk of heart disease)
  2. HDL (High density lipoproteins)- Transport excess cholesterol in the blood back to the liver to be broken down. GOOD cholesterol- lower risk of getting heart disease
  3. Exercise reduces bad LDL cholesterol and increase Good HDL cholesterol
4. Stroke:
  1. When the blood supply is cut off to the brain damaging brain cells so they start to die. Can lead to brain injury, disability and deat
  2. Ischaemic stroke- most common, occur when a blood clot stops blood supply
  3. Haemorrhagic stroke- occur when weakened blood vessel supplying the brain bursts
  4. Exercise lowers blood pressure and helps maintain healthy weight- reduces risk of stroke by 27%
Cardiovascular drift:
1. Steady state- athlete is able to meet the oxygen demand with the oxygen supply
  1. A progressive decrease in stroke volume snd arterial blood pressure, together with a progressive rise in heart rate.
    1. Occurs during prolonged period of exercise, intensity stays the same, heart rate increase, stroke volume decreases, because fluid lost as sweat, resulting in reduced plasma volume, reduced venous return, cardiac output increases due to more energy needed to cool body/ sweat.
      1. To minimise cardiovascular drift, maintain high fluid level before and during exercise
Vascular system:
1. Made up of blood vessels that carry blood through the body delivering oxygen and nutrients to the body tissues and removes waste products
2. Pulmonary - Deoxygenated blood from the heart to lungs & oxygenated blood back to heart
  1. Systemic- Oxygenated blood to body from heart & deoxygenated blood from the body to heart
3. Heart- Arteries- Arterioles- Capillaries- Venules- Veins- Heart
4. Veins- thinner elastic tissue layer, wider lumen and valves
  1. Arteries- High pressure, thin lumen, smooth inner layer, elastic outer layer
    1. Capillaries- one cell thick to allow for diffusion.
Blood pressure:
1. Important to increase blood flow during exercise so the muscles receive oxygen
2. Force exerted by the blood against the blood vessel wall
3. Blood flow X resistance
4. Systolic pressure- Pressure in the arteries when the ventricles are contracting
  1. Diastolic pressure- Pressure in the arteries when the ventricles are relaxing
    1. Measured at the brachial artery (upper arm)- 120mmHg/80
Venous return:
1. The return of blood to the right side of the heart via the vena cava
  1. During exercise venous return increases- more blood is being pumped back to the heart, more blood has to be pumped out, so the volume increases- starlings law
    1. Pressure in large veins is low so hard to return blood to the heart & large lumen means little resistance to blood flow.
2. Skeletal muscle pump- When muscles contract and relax they change shop. This means that the muscles press on the nearby veins causing a pumping affect
  1. Respiratory pump- When muscles contract and relax during breathing pressure changes occur in chest and stomach cavities. This compresses the nearby veins and assist blood return to heart.
    1. Pocket valves- valves ensure blood travels in one direction. Once blood has passed though they close to prevent the blood from flowing backwards
      1. Other factors: Gravity- helps return blood from upper body. The suction pump action of the heart. Thin layer of smooth muscle between walks of veins
3. Impact of blood pressure on venous return:
4. Impact of pressure gradient on venous return:
Transportation of oxygen:
1. During exercise, oxygen diffuses into the capillaries supplying the muscles, 3%dissolves into plasma and 97% combines with haemoglobin to form oxyhemoglobin
  1. When fully saturated, haemoglobin will carry 4 molecules of oxygen. This occurs when the partial pressure of oxygen in the blood is high.
    1. At the tissue oxygen is released due to the lower pressure- oxyhemoglobin dissociation.
      1. In muscle, oxygen is stored by myoglobin. This has high affinity for oxygen and stores the oxygen for the mitochondria (where aerobic respiration occurs) until its used by the muscles
Redistribution of blood:
1. Muscles need more oxygen and blood so its redirected from non-essential organs
  1. Vascular shunt mechanism- redistribution of cardiac output
    1. Don't eat less than an hour before exercise as blood flow is redirected to muscles. Full gut would mean blood would go to stomach instead of muscles which will affect performance was less oxygen available
      1. Blood flow to brain and heart stays constant as both need oxygen for normal function and energy. Blood also goes to skin as energy to cool body down
        Important to: increase the supply of oxygen to working muscles, remove waste products-lactic acid & C02, Ensure blood goes to skin to regulate body temperature, Direct more blood to heart as it requires extra oxygen during exercise
        Pre-capillary sphincters aid- tiny rings of muscle located at the opening of capillaries- contract, restrict blood flow. Relax, blood flow is increased.
2. Control of blood flow:
  1. Vasodilation- widening of the blood vessels to increase blood flow into the capilleries
    1. Vasoconstriction- narrowing of the blood vessels to decrease blood flow to the capillaries
A-V02 Difference
1. The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles
  1. At rest its low as not much 02 is required in muscles but during exercise its high as more oxygen is needed from the blood in muscles
    1. This increases gaseous exchange at the alveoli as more 02 is taken in and more c02 is removed
      1. Trained performers can extract a greater amount of oxygen from the blood

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	Created by milly Dingwall over 4 years ago