2.2 The cardiovascular system Flashcards
What is the function of the cardiovascular system?
Transport:
Oxygen vs Carbon Dioxide, Nutrient delivery from digestive tract, Waste removal, Hormones.
Protection:
Inflammation, WBC destroy microorganisms and cancer cells, Antibodies, Platelets and blood clotting
Regulation:
Body temperature, stabilise pH and fluid distribution.
Where is blood produced?
Red bone marrow site of production of erythrocytes & leucocytes
State the composition of blood
2.1
4 components:
erythrocytes 45%
plasma 55%
leucocytes & platelets <1%
blood transports electrolytes, proteins, gases, nutrients, waste products, hormones
Distinguish between the functions of erythrocytes, leucocytes and platelets.
2.2
Erythrocytes (RBC):
hemoglobin protein binds to oxygen -> oxyhemoglobin.
Leucocytes (WBC):
part of immune system, protects body against infection & foreign invaders. Fight pathogens such as bacteria, viruses, or parasites.
Platelets:
Form blood clots to prevent the loss of blood.
Outline the role of hemoglobin in oxygen transport
RBD site of transport:
Oxygen transported in blood as oxyhemoglobin. Hemoglobin has 4 binding sites for individual O molecules to bind to.
Describe the anatomy of the heart with reference to the heart chambers, valves and major blood vessels.
2.3
Chambers:
Right & Left: Atrium & Ventricle
Valves:
Pulmonary, aortic, tricuspid, bicuspid
Blood vessels:
Aorta, pulmonary vein, pulmonary artery, vena cava
Define pulmonary & systemic circulation
pulmonary circulation- Delivers deoxygenated blood from right side of the heart to the lungs to be oxygenated. Then carried back to left side of heart.
systemic circulation- Delivers oxygenated blood from left side of the heart to the body & capillaries. Then carried back to right side of heart.
Outline the relationship between the pulmonary and systemic circulation.
2.5
-
What are arteries?
thick muscular walls; O2 rich (except pulmonary artery); transport blood away from the heart
What are capillaries?
narrow vessels with thin walls; site of exchange between blood & tissue
What are veins?
deoxygenated blood (except pulmonary veins); less muscular; valves to prevent back flow; to heart
What are valves?
Veins contain valves to stop the blood from flowing backwards due to gravity. This is because the blood inside is at low pressure.
Define:
Cardiac Output (CO) (l/min)
Stroke volume (SV) (l)
Heart Rate (HR) (bpm)
2.6
Cardiac Output (CO) (l/min) - The amount of blood ejected by the heart (ventricles) in 1 minute
-> takes approx 1 min for blood to return & pass through the heart OR. in other wordsAny RBC leaving the left ventricle will be back in approx 1 min
Stroke volume (SV) (l) - The amount of blood being pumped from the heart during each contraction
Heart Rate (HR) (bpm) - How quickly the heart is beating (per minute)
Whats the relationship btw. HR & SV? Why?
2.6
CO = HR x SV
People with higher resting SV have lower resting HR.
-> The more blood you can pump per ventricular contraction, the less your heart needs to beat to pump the blood around your body.
Analyse cardiac output, stroke volume and heart rate data between gender
2.7
-women have lower stroke volume-> smaller heart & smaller left ventricle
-women have smaller blood volume
-women have higher resting & sub-maximal heart rate -> maintain cardiac output
-max heart rate same
Analyse cardiac output, stroke volume and heart rate data between ages
2.7
-children lower stroke volume ->size
-young children have higher resting & working working heart rate -> maintain cardiac output
-w/ age stroke volume increases & heart rate decreases
-older adults have decrease in cardiac output -> bcus of decrease in stroke volume & heart rate
-older adults have much smaller max heart rate
Explain cardiovascular drift.
2.8
the progressive increase in heart rate and decrease in stroke volume that begins after approximately 10 min of prolonged moderate-intensity exercise, is associated with decreased maximal oxygen uptake, particularly during heat stress.
Why does stroke volume decrease, during cardiovascular drift?
Body fluids are lost, reducing the volume of blood returning to the heart causing a decrease in stroke volume
Define the terms systolic and diastolic blood pressure.
2.9
Systolic:
max pressure in the artery during ventricular contraction
(force exerted by blood on arterial
walls during ventricular contraction)
Diastolic:
minimum pressure in the artery during ventricular relaxation (force exerted by blood on arterial
walls during ventricular relaxation)
Analyse systolic and diastolic blood pressure during:
-dynamic exercise
-static exercise
-rest
2.10 & .11
Dynamic exercise- (moderate aerobic exercise)
- systolic pressure increase : first few minutes
- diastolic pressure remains relatively unchanged
Static exercise- (heavy resistance exercise)
- increase blood pressure for both
Recovery - (after a bout of moderate exercise )
- systolic blood pressure temporarily decreases
Compare the distribution of blood at rest and the redistribution of blood during exercise.
2.12
Starling’s Law - the more the heart fills during diastole, the greater the force of contraction
during systole
During exercise blood will move towards the muscles
During rest blood will move to organs (ex. digestion)
Describe the cardiovascular adaptations resulting from endurance exercise training.
2.13
-
Explain maximal oxygen consumption.
2.14
maximal O2 consumption = VO₂ max
-amount of oxygen a person consumes in a set period of time (usually a minute)
⟶ those who have a higher fitness level have higher VO₂ max values and can exercise more
intensely than those who are not as well conditioned
How is VO₂ max calculated?
Fick Equation:
During Max exercise it summarises the relationship between:
Maximum Cardiac Output-(CO)
Maximum Arterio-Venous Difference- (a-v)O2
VO2 Max
VO2 max = Max CO x Max (a-v)O2
What factors affect VO2 max?
2.15
Factors affecting VO2 max:
* Heredity
* Age
* Gender
* Body size and composition
* Mode of exercise
* Types of muscle fibers used during the exercise
* Altitude
* Temperature
* Training status
Discuss the variability of maximal oxygen consumption in selected groups.
2.15
Groups:
Age - decreases with age
Trained vs Untrained - higher in trained and lower in untrained
Male vs Female - higher in males than females
-> Differences in body composition
-> Hemoglobin concentration
How does training increase VO2max?
Increase in stroke volume
-increased in the volume of the left ventricle (sub-maximal & maximal values)
Increased number of capillaries
-so that more blood can supply oxygen to the exercising muscles.
What effect does strenuous exercise have on CO2?
Strenuous exercise can increase CO to 21L/min in a fit person and 35L/min in world-class athletes.
Why should we train if one’s VO2 max is genetic anyway?
We may have a ‘ceiling’ VO2 max that is determined by our genes, but this will only become limiting once a person has trained and increased their VO2max as much as possible to reach this ceiling.
Discuss the variability of maximal oxygen consumption with different modes of exercise.
2.16
Highest values: treadmill exercise
-> more muscles are being used
Lowest values: bicycle ergometer test
arm ergometry
->participant is sitting down and only using their
arms, which requires less oxygen going to the muscles
What is affected by training more HR or SV?
- Our maximum HR remains the same, however with training one can tolerate a higher HR for longer.
- SV is affected the most by training as physical changes to the heart (increase in the left ventricle) result in a higher SV, thus more cardiac output. (CO)
Explain Absolute VO2 max vs Relative VO2 max.
Absolute VO2 Max: Does NOT account for differences in size and mass Expressed in L/min Relative
Relative VO2 Max: Does account for differences in size and mass. Expressed in ml/kg/min
What is Max (a-v)O2
The (a-v)O2 is an indication of how much oxygen has been removed by the capillaries and used by the body.
What is intrinsic regulation of the heart rate?
2.4
The intrinsic regulation of heart rate means that the heart can beat on its own without needing commands from the brain, thanks to special cells that act like a natural pacemaker.
What is the extrinsic regulation of the heart rate?
2.4
Extrinsic regulation of heart rate involves external factors, such as signals from the nervous system and hormones, which influence the heart rate in response to changes in the body’s needs or conditions, like during exercise or stress.
Outline intrinsic regulation of the heart rate.
2.4
Heart stimulates itself to contract –> Pacemaker system
- SA node (pacemaker) fires a cardiac impulse, starts in wall of right atrium, causing the 2 atria to contract simultaneously (almost)
- W/ slight delay, cardiac impulse reaches the AV node, giving ventricles time to fill with blood.
- Impulse then passes down septum of heart which splits left & right around heart -> impulse spread around walls of ventricles so they contract again.
- Ventricles relax & cycle repeats
What is the role of extrinsic regulation of the heart rate?
While heart is able to contract by itself, it needs info. from body to speed up or slow down. It gets this info. from:
-
Chemoreceptors - Detect changes in blood pH, carbon dioxide and oxygen. In the aortic arch, carotid arteries send information to the cardiac centre in the brain stem.
(same receptors as in respiratory/ventilatory system) -
Baroreceptors – Blood Pressure Receptors.
-When HR drops, send impulses to the cardiac centre
Cardiac Centre sends a signal back to the heart increasing the firing rate of the SA node bringing the HR, CO and Blood Pressure back to normal. When it spikes, so to does blood pressure at the Baroreceptors. (present in the aorta and internal carotid arteries) - Proprioceptors. are sensors that provide information about joint angle, muscle length, and muscle tension. Detect changes in physical activity & allow heart to change output before muscles require extra oxygen.
- Emotions & Drugs. (Example) caffeine will stimulate the Sympathetic & speeding up the SA node thus releasing adrenaline. K+ potassium and calcium deficiency causes the parasympathetic nervous system to release acetlycholine which decreases HR.
What is blood pressure?
measurement of the force of blood against the artery walls as the heart pumps it throughout the body
How is a blood pressure reading expressed? (which numbers?)
Systolic blood pressure
Dystolic blood pressure
