Cardiovascular System when exercising/recovering Flashcards
Effect of exercise on cardiac output
How will it move in correlation to exercise intensity?
What happens to it during maximum exercise?
- Cardiac output will increase linearly until maximum exercise capacity where it will plateau
- During maximum exercise, cardiac output may reach values of between 4-8 times resting values
Stroke volume response to exercise
How will it move in correlation to exercise intensity? (2 things)
Able to increase for 2 reasons: (2 reasons)
- SV increases linearly with increasing intensity, this only happens up to 40-60% of maximum effort.
- After which stroke volume plateaus - reason for this is shorter diastolic phase (ventricular)
Able to increase for various reasons:
- Increased venous return - Starlings law – with increased venous return more blood enters the ventricles which causes them to stretch more leading to a greater contract more forcefully
Heart rate response to sub maximal exercise (3 parts)
- Prior to exercise there is an increase in heart rate, known ‘anticipatory rise’ which is the result of the release of adrenaline
- Heart rate will increase linearly in direct proportion to intensity but by how much and how quick is dependent upon the intensity of the exercise.
- there is likely to be a plateau which represents the demand for O2 is being met by the O2 supply
Heart rate response to maximal exercise (2 parts)
- This will see an increase at a faster rate initially and then slow down.
- Once the event is over with the heart rate will initially decrease rapidly and then slow down
Circulatory system
Purpose?
Two types and what do they do?
Is responsible for the movement of oxygen and carbon-dioxide around the body.
There are two circulatory systems in the body, these are referred to as the:
- Systemic circulation system
- transports oxygenated blood around the body from the left ventricle through arteries and arterioles
- returns deoxygenated blood to the right side of heart through veins
- Pulmonary circulation
- Deoxygenated blood is transported from the right ventricle to the lungs via the pulmonary artery where it is re-saturated with O2
- returns to the left side of the heart via the pulmonary vein
Arteries/arterioles (3 features and what are they essential for?)
- Thick elastic walls
- Small lumen
- Smooth muscle layer
Carries blood away from the heart and essential to the re-distribution of blood
Capillaries (2 features and what do they do?)
- Narrow diameter
- One cell thick
Facilitates the exchange of gases and other nutrients between the blood and tissues
Veins/venules (3 features and what is it essential for?)
- Thin layer of smooth muscle
- Wider lumen
- Possess pocket valves
Essential in the return of blood to the heart
Venous return
Definition?
How much blood is held in the veins and what effect does it have?
What happens when we first stop exercising?
What do we do and have, that reverses this?
- the volume of blood that returns to the right side of the heart via the venae cava, veins and venules.
- 70% of the total volume of blood is held in the veins and acts as a large storage depot which can be called upon quickly when needed such as when we are exercising. If blood flow is to increase during exercise venous return must also increase.
- When we first stop exercising our cardiac output is still high, and the pressure within the body to return the blood back to the heart. Blood pooling occurs and blood sits within the pocket valves, in the veins and sometimes they may experience a sense of dizziness
- To ensure that venous return is maintained, the performer should carry out an active recovery. This will assist the muscle and respiratory pumps in returning blood to the heart.
Factors affecting Venous Return
Skeletal muscle pump:
- contraction and relaxation of muscles create a massaging effect which aids in squeezing blood back to the heart
Smooth muscles within veins:
- Located within the walls of the veins is a thin layer of smooth muscle and squeezes the vein forcing blood back to the heart
Gravity:
- Assists the flow of blood from the upper extremities of the body
Respiratory pump:
- Increased rate and depth of breathing, creates pressure within the thorax. Breathing in, increases pressure which compresses on veins and squeezes blood in veins which supply the heart
Pocket valves :
- These snap shut ensuring the flow of blood travels in one direction – back towards the heart
Control of heart rate
The rate at which impulses are fired is…?
What happens when we exercise and what needs to happen?
What controls the regulation of the heart rate?
- The rate at which the impulses are fired is external to the heart
- When we exercise the heart rate must increase, and the SA-node must fire impulses more rapidly in order to meet the body’s demand for O2
- Regulation of the HR is under control of the cardiac control centre (CCC) in the medulla oblongata, which forms part of the autonomic nervous system (ANS)
Cardiac Control Centre (CCC) in the Medulla Oblongata (causes and response)
Causes
Mechanoreceptors and proprioreceptors:
- These detect movement/muscular contractions
- inform the CCC
- HR increases
Chemoreceptors:
- Detect an increase in blood acidity/decrease in pH/ increase in CO2
- informs the CCC
- HR will increase
Baroreceptors:
- Detect an increase in blood pressure and stretch receptors exist in the walls of the aorta, vena cava detect a change in blood flow and therefore blood pressure.
- Informs the CCC
Response
CCC responds to this information by stimulating the SA node via the sympathetic nervous system OR cardiac acceleratory nerve
Anticipatory rise (3 parts)
- Prior to exercise you may experience butterflies along with an increase in heart rate
- Largely due to the hormone adrenaline being released through the adrenal glands in the blood stream.
- Adrenaline will prepare the body for the impending exercise by increasing heart rate and strength of ventricular contraction.
During exercise adrenaline and noradrenaline can aid the body’s response to exercise by: (3 things)
What happens after exercise? (2 things)
- Increasing heart rate
- Constricting blood vessels which increases blood pressure helping blood to reach active muscles
- Increase blood glucose levels by stimulating the break down of glycogen in the liver (this fuels muscular contractions)
When we stop exercising:
- The parasympathetic nervous system take over.
- The nerves here release acetylcholine which causes a decrease in heart rate.
Role of blood CO2 in changing heart rate (3 steps + 1 extra thing that will come into effect)
- During exercise CO2 levels rise which leads to increase in acidity/low pH
- This is detected by the chemoreceptors and impulses are sent to the CCC in the medulla oblongata increasing stimulation of the sympathetic nerve
- Adrenaline is released and causes impulse to continue to the SA node which causes an increase in HR, SV and VE
Starlings law will also come into effect
