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A-Level Physical Education > Cardiovascular system :) > Flashcards

Cardiovascular system :) Flashcards

1
Q

cardiac conduction system

A
  1. from sinoatrial node, electrical impulse spreads causing walls to contract - atrial systole
  2. then atrioventricular node delays for 0.1 seconds for atria to fully contract
  3. bundle of HIS
  4. bundle branches
  5. purkinje fibres spreading through ventricles causing ventricular systole
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2
Q

neural control mechanism

A

sympathetic nervous system stimulating heart to beat faster and parasympathetic nervous system returning it to normal

located in cardiac control centre in medulla oblongata

chemoreceptors - detect blood co2 increase - ccc - sympathetic system - san increases heart rate

baroreceptors - detect blood pressure increase - ccc - parasympathetic system - san decreases heart rate

proprioceptors - detect muscle movement increase - ccc - sympathetic system - san increases heart rate

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3
Q

hormonal control mechanism

A

anticipatory rise- increase in heart rate prior to exercise, due to the release of adrenaline

adrenaline is a stress hormone released by sympathetic nerves which stimulates the san and increases the speed and force of contraction - increasing cardiac output

more blood pumped to working muscles- more oxygen

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4
Q

stroke volume

A

volume of blood pumped out by heart ventricles in each contraction - average is 70 ml

depends on:

  • venous return- when increases sv increases too
  • elasticity of cardiac fibres- degree of stretch when heart is relaxed (diastole) the more stretch, the greater the force of contraction = increased ejection fraction
  • contractility of tissue - more the cardiac tissue contracts the greater the sv

increases during exercise up to 40-60 of max effort then sv plateaus as no time to fill more

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5
Q

ejection fraction

A

the percentage of blood pumped out by left ventricle per beat

relationship with stroke volume

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6
Q

starling’s law

A

increased venous return - greater diastolic filling - cardiac muscles stretched - bigger force of contraction - increased ejection fraction

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7
Q

heart rate

A

heart rate increases with exercise in direct proportion to intensity

maximum heart rate is 220 - age

trained performer has a greater heart rate range as resting heart rate is lower and max heart rate increases

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8
Q

trained performers heart

A

regular training leads to more cardiac muscle

cardiac hypertrophy - heart becomes bigger and stronger due to thickened muscle walls

bradycardia - decrease in resting heart rate to 60 bpm or below due to stronger heart enabling more blood to be pumped out each beat
-better oxygen delivery as less oxygen used for heart beats

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9
Q

cardiac output

A

amount of blood pumped from the heart every minute

heart rate x stroke volume

during exercise there is big increase due to increased hr and sv, increase in proportion to exercise intensity until maximum is reached

at rest co is same for trained and untrained performers but maximum cardiac output is different
-during exercise trained performer can transport more blood and oxygen to working muscles

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10
Q

heart disease

A

atherosclerosis: coronary arteries (supply blood to heart with oxygenated blood) become blocked or narrow due to build up of fatty deposits (atheroma)
angina: arteries getting smaller so able to deliver less oxygen causing pain and discomfort

caused by: high blood pressure, high cholesterol levels, lack of exercise and smoking

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11
Q

high blood pressure

A

blood pressure is force exerted by blood against blood vessel wall

high blood pressure puts extra strain on arteries and increases risk of heart failure, heart attack, kidney disease, stroke or dementia

regular exercise can reduce blood pressure, lowering diastolic and systolic pressure by 5-10 mmHg

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12
Q

cholesterol levels

A

two types of cholesterol:

LDL transports bad cholesterol linked to hear disease into blood and tissue
HDL transports excess good cholesterol back to liver to be broken down

regular physical activity lowers LDL and increases HDL

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13
Q

stroke

A
  • occurs when blood supply to part of the brain is cut off, causing damage to brain cells so they die
  • brain needs constant supply of oxygenated blood and nutrients to function

two types of stroke:
ischaemic- most common and occurs when blood clot stops blood supple
haemorrhagic- weakened blood vessel supplying blood bursts

regular exercise helps maintain healthy body weight reducing risk of stoke by 27%

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14
Q

cardio vascular drift

A

progressive decrease in stroke volume + blood pressure with a rise in heart rate

happens during prolonged exercise (10+ mins) in a warm environment

plasma volume reduced bc of more sweating

venous return and stroke volume reduces which increases heart rate

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15
Q

venous return

A

return of blood to the right side of heart via vena cava- increases during exercise

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16
Q

venous return mechanisms

A

skeletal muscle pump- muscles contracting and relaxing so they press on nearby veins and pump/squeeze blood up to heart

respiratory pump- muscles that contract and relax during breathing change pressure in chest and stomach assisting blood flow to heart

pocket valves- valves ensure blood only flow one way through veins

smooth muscle- helps squeeze blood back to heart

gravity- helps blood return

17
Q

impact of blood pressure on venous return

A

increasing right arterial pressure – decreases venous return

18
Q

blood vessels

A

veins transport deoxygenated blood back to heart
{thinner muscle layers, lower pressure, valves and wider lumen}
arteries transport oxygenated blood around the body
{highest pressure, thick elastic walls and walls, smaller lumen, smooth inner layer}
capillaries only wide enough for one red blood cell
{slower blood flow, exchange of nutrients with tissues via diffusion}

19
Q

vascular shunt mechanism

A

during exercise skeletal muscles require more oxygen so blood needs to be redirected to where it is most needed- vascular shunt mechanism or blood-shunting

important to:

  1. increase supply of oxygen to working muscles
  2. remove waste products like lactic acid + co2
  3. ensure blood goes to skin to regulate body temp (sweating)
  4. direct more blood to heart as big working muscle
  5. important to ensure gut it empty to stop blood going to stomach
  6. brain blood flow maintained for brain function
20
Q

control of blood flow

A
  • controlled by vasomotor in medulla
  • increase in co2 and lactic acid detected by chemoreceptors

vasodilation: widening of blood vessels to increase blood flow into capillaries
- happens in arteries during exercise
vasoconstriction: narrowing of blood vessels to decrease blood flow into capillaries
- happens at non-essential organs like intestines

sympathetic nerves can also be stimulated in blood vessel walls that increases vasoconstriction

21
Q

pre-capillary sphincters

A

tiny rings of muscles at the opening of capillaries

  • when they contract, blood flow is restricted
  • when they relax blood flow is increased
22
Q

myoglobin

A

protein in muscle that has a higher affinity for oxygen then haemoglobin

stores oxygen in muscle fibres that can quickly be used when exercise starts

23
Q

haemoglobin

A

carries blood around the body

24
Q

oxyhaemoglobin dissociation- at rest

A

curve represents relationship between oxygen and haemoglobin

at tissues: haemoglobin gives up some oxygen to tissues due to lower partial pressure of oxygen think of like diffusion

at lungs: haemoglobin almost completely saturated with oxygen due to high partial pressure of oxygen

25
Q

oxyhaemoglobin dissociation- during exercise

A

during exercise the curve shifts to the right as the muscles require more oxygen

haemoglobin dissociation in capillaries to the muscles happens more readily (faster) to allow a higher % of oxygen to be released at lower pH

in tissues there is low partial pressure of oxygen and high partial pressure of carbon dioxide to haemoglobin releases it here

26
Q

bohr shift

A

as mucles require more oxygen, the dissociation of oxygen from haemoglobin happens more readily

factors responsible:

  • increase in blood temp-
  • partial pressure of co2-
  • decrease in blood pH- more co2 lowers pH
27
Q

a-vo2 diff

A

difference between the oxygen content of arterial blood arriving at the muscles and venous blood leaving muscles

-at rest a-vo2 is low as not much oxygen required

  • during exercise more oxygen is needed so a-vo2 high
  • increase affects gaseous exchange so more oxygen is taken in and more carbon dioxide removed
  • trained performers have increased a-vo2 diff as they can extract a greater amount of oxygen from blood
28
Q

blood pressure

A

systolic pressure-ventricles are contracting

diastolic pressure- ventricles are relaxing

29
Q

redistribution of blood

A

A-Level Physical Education (30 decks)

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