2.2 Structure and function of the cardiovascular system Flashcards
What three elements make up the cardiovascular system?
Heart, blood, blood vessels
State the composition of blood
Plasma - 55%
White blood cells (leukocytes and platelets) - <1%
Red blood cells (erythrocytes) - 45%
What is the function of erythrocytes?
Carry & transport oxygen and carbon dioxide
Contains an iron-rich protein called haemoglobin
Oxygen binds to haemoglobin to be transported around the body as oxyhaemoglobin
What is the function of leukocytes?
Protection from infectious diseases and foreign substances
One part of the body’s immune system
What is the function of platelets?
Blood clotting and repair damage to cells
Stops the spread of pathogens
Another part of the body’s immune system
BE ABLE TO LABEL
THE HEART - ALL OF THE BITS
What are the two intrinsic regulators?
Sinoatrial node (SA node)
Atrioventricular node (AV node)
(heart has a pacemaker of it’s own creating electrical impulses in the muscular walls)
Summarise the regulator process
SA node generates nerve impulses that travel throughout the heart wall. This causes both atria to contract.
SA node impulses meet AV node there’s a delay of about 0.1 seconds.
This delay allows atria to empty into ventricles, before ventricles contract.
AV node generates nerve impulses that travel through the septum which cause the ventricles to contract.
What are the three extrinsic regulators?
Sympathetic, parasympathetic, adrenaline (overrides the intrinsic regulation of the heart)
What are sympathetic regulators?
Connected to the heart via the sympathetic cardiac nerve
Responsible for increasing heart rate
Increases the force of cardiac muscle contractions
What are parasympathetic regulators?
Slows down your heart rate
Connected to the heart via the vagus nerve
Responsible for slowing the heart rate
Vagus nerve decreases the force of cardiac muscle contractions
What are adrenaline regulators?
Released from the adrenal glands which increase the heart rate and the force of contraction.
Also increases breakdown of glycogen and lipids and redistribution of blood to the skeletal muscles.
BE ABLE TO LABEL AND DRAW
of blood going around the body from the lungs to the heart to the body, oxygenated blood and deoxygenated blood
What is the first step in circulation? P or S
Deoxygenated blood enters the right atrium through the superior and inferior vena cava S
What is the second step in circulation?
Deoxygenated blood travels through tricuspid valve and into the right ventricle S
What is the third step in circulation?
Deoxygenated blood leaves the heart through the pulmonary artery and returns to the lungs P
What is the fourth step in circulation?
Gaseous exchange takes place. CO2 deposited. O2 taken into the bloodstream P
What is the fifth step in circulation?
Oxygenated blood leaves the lungs and goes back to the heart through the pulmonary vein P
What is the sixth step in circulation?
Enters the left atrium P
What is the seventh step in circulation?
Travels through the bicuspid valve to the left ventricle S
What is the eighth step in circulation?
Oxygenated blood leaves the heart through the aorta S
What is the ninth step in circulation?
Oxygenated blood travels to the systems in the body such as liver, kidneys S
What does cardiac output mean + formula?
Amount of blood pumped by each ventricle in one minute - amount of blood ejected by the heart per minute = stroke x heart rate
What does stroke volume mean?
Volume of blood ejected by the heart per beat
What does heart mean?
Beats per minute BPM
What is the equation that connects these key words?
Cardiac output = stroke volume x heart rate
What happens to heart rate, cardiac output, and stroke volume during exercise?
Increased amount of oxygen in the working muscles.
Demands increase in cardiac output (Q)
Stroke volume expands and heart rate increases during exercise
What adaptations occur as a result of endurance training?
Cardiac hypertrophy (increased muscle size)
Increased capillarisation
Increased arterio-venous oxygen difference
Explain cardiac hypertrophy
Specifically left ventricular volume increases, leading to increased stroke volume and decreased resting heart rate
Explain increased capillarisation
Moore capillaries surrounding each muscle fibre
Explain arterio-venous oxygen difference
Greater difference between oxygen in arteries and venioles
How does VO2 max change in males and females?
Females usually have a lower relative VO2 max, primarily due to size difference. Even in relative terms they have a lower value then males. Males have a higher haemoglobin content. Females have a higher amount of non-oxygen-using body fat.
How does VO2 max change in young and old?
Peaks in early 20s for males and mid-teens for females. Children have a lower VO2 max than adults. From adulthood relative VO2 max typical declines by 1% a year. In relative terms male children have a similar VO2 max compared to an adult
What is VO2MAX?
Maximum amount of oxygen a person can utilise during intense exercise
What unit is VO2MAX measured in?
ml of oxygen used per kg in a minute (ml/kg/min)
Which component of fitness is VO2MAX an indicator of?
Cardiorespiratory endurance
variability of MAXIMAL OXYGEN consumption in selected groups AND
variability of MAXIMAL OXYGEN consumption with different modes of exercise
What is blood pressure?
The pressure exerted by the blood on the arterial walls
What is systolic blood pressure?
The force exerted by the blood on arterial walls during ventricular contraction
What is diastolic blood pressure?
The force exerted by blood on arterial walls during ventricular relaxation
Why is ELEVATED BLOOD pressure
DANGEROUS
How does the blood pressure change when moving from rest to exercise?
Systolic pressure increases as a result of increased cardiac output, caused by increased HR and SV
Diastolic pressure remains relatively unchanged
As exercise intensity increases, so does systolic pressure
If steady state exercise is prolonged systolic pressure can start to decrease
How does dynamic and static exercise affect blood pressure differently?
Dynamic exercise: increase of systolic in the first few minutes and then stablises after 2/3 mins of exercise of a given intensity; diastolic pressure remains relatively unchanged
Static exercise: can increase both systolic and diastolic blood pressure dramatically, compresses peripheral arteries increasing the resistance to blood flow
What is cardiovascular drift?
After 10 minutes of prolonged moderate-intensity constant intensity exercise there will be a progressive decline in stoke volume, an increase in heart rate, and a constant cardiac output in order to give working muscles oxygen
Explain reasons for cardiovascular drift
Hydration reduces stoke volume, cardiac output stays the same, heart rate has to increase. Hydration can worsen cardiovascular drift. Can normally be observed in a non-endurance trained person during which there are progressive but small increases in the persons core temperature ??
How does the body prevent overheating?
Blood vessels on the surface of the skin vasodilate to allow blood flow to the skin and to release heat
Dehydration contribution explained
During prolonged exercise, we begin to sweat meaning we lose water from the body, some of which comes from the blood therefore increasing blood viscosity. Lower level of blood volume = decrease stroke volume
What type of exercise causes cardiovascular drift?
Prolonged moderate intensity training
What are the cardiovascular adaptation from endurance exercise?
Increased left ventricular volume
Increased stroke volume
Increased capillarisation
Lower resting and exercising heart rate
Increased arteriovenous oxygen difference
What is vasoconstriction?
Blood vessels reduce in diameter
Reduces blood flow
What is vasodilation?
Blood vessel increases in diameter
Increases blood flow
What is the precapillary sphincter?
Stops and allows blood flow
What happens to the blood usage during exercise?
Blood flow is redistributed away from non-essential body parts to working muscles.
During sustained exercise blood flow is directed to the skin to aid cooling through radiation.
—> This reduces the blood flow to working muscles slightly which emphasises the need to keep cool during sustained exercise
Both of these functions are facilitated by vasoconstriction and vasodilation
How is the blood received by the heart?
Atrium receives blood through a vein and then atria contacts and pushes the blood into the ventricles
How is the blood ejected through the heart?
The ventricles then contract, the blood is pushed out of the heart and carried away from the heart via arteries.
