Cardio Vascular System Flashcards
Define Myogenic
The capacity of the heart to generate its own impulses
Name the order of the pulse through the heart
SAN > Atrial Systole > AVN > Bundle of His > Bundle Branches > Purkinje Fibres > Ventricular Systole
What does the sympathetic nervous system do ?
Increase heart rate
What does the parasympathetic nervous system do ?
Decrease heart rate
What do Chemoreceptors do and how does this affect heart rate ?
Detect the content of carbon dioxide in the blood
↑ CO2 = ↑ Heart Rate
What does the Medula Oblongata do ?
It regulates vital processes
What do Baroreceptors do and how does this affect heart rate ?
Establish a set point for blood pressure
Any increase or decrease sends a signal to the Medulla Oblongata
↑ Arterial Press = ↓ Heart Rate
↓ Arterial Press = ↑ Heart Rate
What do Proprioceptors do and how does this affect heart rate ?
Detect and send information about body movement and position
↑ Movement = ↑ Heart Rate
↓ Movement = ↓ Heart Rate
How do hormones affect heart rate ?
Adrenaline – Stress Hormone
Stimulates SAN to increase Heart rate and Strength which causes an increase in Cardiac Output
Define stroke volume
Volume of blood pumped out per beat
Define cardiac output
Volume of blood pumped out per minute
Define ejection fraction
Percentage of blood pumped out by the left ventricle per beat
Define venous return
Volume of blood returning to the heart through the veins
What is the equation for cardiac output
Cardiac Output = Stroke Volume x Heart Rate
What is Sterling’s Law ?
A greater force of contraction means an increase in ejection fraction
Define Bradycardia
A resting heart rate of less than 60
What are the benefits of aerobic exercise ?
Cardiac hypertrophy
Lower resting heart rate
Larger ventricular cavities
Increased stroke volume and diastolic volume
More oxygen delivered to the muscles
Large increase to Cardiac Output
Define steady state
When oxygen demand and supply are equal
What happens during cardiovascular drift ?
Progressive decrease in stroke volume and arterial blood pressure
Progressive increase in heart rate to compensate
What are the conditions for cardiovascular drift to occur ?
Occurs during prolonged exercise in a warm environment after approximately 10 minutes
What causes cardiovascular drift ?
Caused by sweating as a proportion comes from blood plasma supply
Lower plasma volume causes blood to become more viscous
How can cardiovascular drift be prevented
Plenty of fluid should be consumed regularly
What is the pulmonary circuit ?
Heart > Lung
What is the systemic circuit ?
Heart > Body
what are the 5 types of blood vessels ?
Arteries
Arterioles
Capillaries
Venules
Veins
What happens to blood pressure during exercise ?
During exercise systolic pressure increases and diastolic pressure decreases
Name the 6 types of venous return
Skeletal muscle pump
Respiratory pump
Pocket valves
Gravity
Suction pump
Smooth muscle in wall of veins
Explain how the skeletal muscle pump works
When muscles contract and relax they change shape therefore pressing on the nearby veins
Explain how the respiratory pump works
When muscles contract and relax during breathing in and out, pressure changes occur which compress the nearby veins
Explain how pocket valves works
Important blood in veins only flows in one direction
Explain how exercise affects which venous return mechanisms are used
Rest - Smooth muscle and valves in veins are enough
Exercise - Need skeletal muscle and respiratory pump to aid return
Post - Still need to maintain these mechanisms
What is the impact of pressure on venous return ?
Linked very closely to systolic pressure
When systolic pressure increases, venous return also increases
What is Coronary heart disease ?
When the Coronary arteries become blocked or begin to narrow due to a build up of fatty deposits (Atheroma)
Atherosclerosis
What can CHD be caused by ?
High blood Pressure
High cholesterol levels
Lack of exercise
Smoking
What is Angina ?
As coronary arteries become blocked, oxygen cant be delivered to the heart therefore causing pain/discomfort
What can CHD lead to ?
If a atheroma breaks off it can cause a blood clot which cuts off the oxygen supply to the heart which therefore causes a heart attack
What can high blood pressure increase the risk of ?
Heart attack
Heart failure
Kidney disease
Stroke
Dementia
What is normal blood pressure ?
Systolic - less than 120
Diastolic - less than 80
What are the 2 types of cholesterol ?
LDL (Low density lipoproteins)
HDL (High density lipoproteins)
What are the characteristics of LDL ?
Transports cholesterol in blood to tissues
Classed as ‘bad’
Linked to increase risk of heart disease
What are the characteristics of HDL ?
Transports excess cholesterol in the blood to the liver where it is broken down
Classed as ‘good’
Linked to decrease risk of heart disease
What is a stroke ?
When blood supply to the brain is cut off causing damage to brain cells
What can a stroke lead to ?
Brain injury
Disability
Death
What are the 2 types of strokes and explain them ?
Ischaemic - When a blood clot stops the blood supply
Haemorragic - When a weakened blood vessel supplying the brain bursts
What are the symptoms of a stroke ?
Face drooping
Arm weakness
Speech difficulties
What are the 3 ways blood can be transported around the body ?
Plasma
Haemoglobin
Myoglobin
How many molecules are on a fully saturated haemoglobin and when does it occur ?
4 molecules of oxygen
Occurs when partial pressure of oxygen is high
What is oxyhaemoglobin dissociation ?
The release of oxygen at tissues/skeletal muscles due to lower partial pressure
Where is oxygen stored in the muscles ?
In the myoglobin because it has a higher affinity for oxygen
What is Bohr shift ?
When muscles require more oxygen, the dissociation occurs more readily, causing the graph to shift to the right
Causes of Bohr shift
Increased blood temperature
Increased partial pressure of carbon dioxide
Lower pH level
What is vascular shunting ?
The redistribution of cardiac output around the body
Key areas of vascular shunting
Brain
Heart
Skin
What controls the blood pressure and flow ?
The vasomotor centre which is located in the medulla oblongata
What happens to blood vessels during exercise ?
Vasodilation - Widening of the lumen
Vasoconstriction - Narrowing of the lumen
What does sympathetic stimulation do to blood vessels ?
Vasoconstriction
Reduced blood flow
What are pre-capillary sphincters ?
Tiny rings of muscle at the opening of capillaries
Why is blood redistribution important ?
Increased oxygen delivery to active muscles and heart
Remove waste products
Ensure blood goes to skin to cool down
What is A-Vo2 diff ?
The difference in oxygen content between the arteries and veins at the muscle
