1.1 Cardiovascular System Flashcards
Health
A state of complete physical, mental and social well-being and not merely the absence of disease and infirmity/injury.
Fitness
The ability to meet the demands of the environment
Physical activity
Being active and taking part in exercise - can directly benefit your physical health and wellbeing.
Heart rate (HR)
The number of times the heart beats per minute
Anticipatory rise
Slight increase in heart rate usually before activity starts due to the expectation of exercise
Stroke Volume (SV)
The volume of blood that leaves the heart during each contraction
Cardiac output (Q)
The amount of blood the heart pumps out per minute . Measured in litres per minute (L/min)
Q = SV xHR
Systole
Term used to describe the contraction phase of the cardiac cycle - the ventricles contract and pump blood to the arteries
(RV to the pulmonary artery and lungs, LV to the aorta and the body)
Diastole
Term used to describe the relaxation phase of the cardiac cycle.
The heart ventricles are relaxed and fill with blood
What is the Cardiac cycle ?
The mechanic event of ONE heart beat
Explain the diastole phase
The relaxation phase of the cardiac cycle
1. The heart at this point is relaxing and filling up with blood.
2. The atria fill with blood and pressure builds within these chambers.
3. As the pressure increases, the valves begin to slowly open and let small amounts of blood through.
Explain the systole phase
( the contraction part of the cardiac cycle)
Pressure has built up in the atria during diastole phase.
ATRIAL SYSTOLE PHASE
1. Valves are now forced open, both atrial contract and remaining blood is forced into ventricles.
VENTRICULAR SYSTOLE PHASE
1. Blood is now in ventricles, ventricles now contract increasing the pressure within these chambers.
2. Aortic valve and Pulmonary valve are forced open, allowing blood to be pushed through into the Aorta or Pulmonary Artery.
The heart muscle is myogenic. What does this mean?
The ability of the heart to generate its own electrical impulses – the heart muscle starts the beat itself with the electrical signal from the SAN – spreads across the heart like a Mexican wave and is called a wave of excitation.
Explain the Conduction System of the heart
Impulse starts in the SINOATRIAL NODE (SA NODE)
Then the pulse travels down into the ATROVENTRICULAR NODE (AV NODE) and onto the BUNDLE OF HIS.
These impulses here stimulate the atria (0.1 second delay)
From here, the pulse travels down the left and right branches and down into the PURKINJE FIBRES.
Here the ventricles are squeezed.
Short term effects of exercise
- Increased HR due to rising adrenaline levels
- Increase in Stroke Volume due to stronger ventricular contractions
- Increase Cardiac Output
Long term effects of Exercise
- Decrease in RHR
- Thicker left ventricle wall
- Increase in resting stroke volume - more typical in endurance athletes
- hypertrophy of the heart
- increase number of capillaries in muscles = more efficient oxygen delivery to muscles
- improvement in cardiac output during exercise
- increase in blood volume = increase in red blood cells to carry more oxygen
Name the four chambers of the heart
Right atrium and right ventricle Left atrium and left ventricle
Which chambers are larger? Explain why ?
The ventricles are larger because they have to pump the blood further
Which side of the heart is larger ? Explain why ?
Left as it has to push blood around the whole body compared to the right that only pushes blood to the lungs
Name the main blood vessels that enter and leave the heart
Vena Cavae – from body to right atrium, pulmonary artery from RV to lungs, pulmonary vein from lungs to left atrium, aorta from left ventricle to body and back to the vena cavae
What are the names of the valves in the heart and where are they located ?
Tricuspid – between RA and RV
Bicuspid valve between LA and LV
Semi lunar valves – in the pulmonary artery (stops backflow into the RV) and the aorta (stops back flow into the LV)
What is the main function of the valves ?
Prevents back flow of blood
Starting at the venae cavae (inferior and superior vena cava), place the following structures in the correct order that a red blood cell would pass on its journey through the heart
Venae cavae – RA – Tricuspid valve – RV – semilunar valve – pulmonary artery – lungs – pulmonary vein – LA – bicuspid valve – LV – semilunar valve - aorta - body
What is the order that the impulse through the heart travels in
SAN - atrial systole – AVN – bundle of His – bundle branches – purkinje fibres –
ventricular systole
What happens to HR during a football match ?
The heart rate fluctuates as intensities during the match change ie. Standing, jogging or sprinting.
Sinoatrial node (SAN)
A small mass of cardiac muscle found in the wall of the right atrium that generates the
heartbeat. It is more commonly called the pacemaker.
Atrioventricular node (AVN)
This node relays the impulse between the upper and lower sections of the heart.
Systole
When the heart contracts
Bundle of His
A collection of heart muscle cells that transmit electrical impulses from the AVN via the bundle branches to the ventricles.
Purkinje fibres
Muscle fibres that conduct impulses in the walls of the ventricles.
What are the factors affecting the change in rate of the conduction system ?
- Sympathetic nervous system
- parasympathetic nervous system
- medulla oblongata
How does the heart know to speed up ?
The Automatic Nervous System (ANS) determines the rate at which the SA Node sends out impulses
Sympathetic nervous system
A part of the autonomic nervous system that speeds up heart rate by releasing adrenaline .
Parasympathetic nervous system
A part of the autonomic nervous system that decreases heart rate . Releases acetylcholine which slows the spread of impulses throughout the heart.
What two parts are the nervous system made up of ?
- The central nervous system (CNS) - brain and the spinal cord
- The peripheral nervous system - nerve cells that transmit information to and from the CNS
Medulla oblongata
The most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate
What is the cardiac control system controlled by ?
Chemoreceptors - carotid arteries , aortic arch
Baroreceptors - heart
Proprioceptors - ligaments ,tendons, muscles
Chemoreceptors
Tiny structures in the carotid arteries and aortic arch that detect chemical changes . During exercise chemoreceptors detect an increase in carbon dioxide. An increased concentration of carbon dioxide in the blood will have the effect of stimulating the sympathetic nervous system, which means
the heart will beat faster.
Baroreceptors
Special sensors in tissues in the aortic arch, carotid sinus, heart and pulmonary vessels that respond to changes in blood pressure to either increase or decrease heart rate. Increase in bp—>decrease in HR
Proprioceptors
Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement. These receptors then send an impulse to the medulla, which then sends an impulse
through the sympathetic nervous system to the SAN to increase heart rate.
Adrenaline
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in heart rate.
Ejection fraction
The percentage of blood pumped out by the left ventricle per beat.
Venous return
The return of blood to the right side of the heart via vena cava
Structure and function of veins
- carry blood towards the heart
- mostly carry deoxygenated blood ( not pul vien )
- No stretch - very thin layer of smooth muscle
- Thin walled large lumen have valves to prevent back flow
Starlings law
If more blood is being pumped into the heart the more blood will need to be pumped out .So SV increases , this is starlings law. This occurs during exercise,when this happens venous return will increase
Plasma
The fluid part of blood (mainly water) that surrounds blood cells and transports them
Haemoglobin
An iron-containing pigment found in red blood cells , which combines with oxygen to form oxyhaemoglobin
Myoglobin
Often called ‘muscle haemoglobin’. It is an iron-containing muscle pigment in slow-twitch muscle fibres which has a higher affinity for oxygen than haemoglobin. It stores the oxygen in the muscle fibres which can be used quickly when exercise begins
Mitochondria
Often referred to as the ‘powerhouse’ of the cell as respiration and energy production occurs there
What are the 6 venous return mechanisms ?
- The skeletal muscle pump
- The respiratory pump
- Pocket valves or Valves
- Smooth muscle in the walls of veins
- Gravity
- The suction pump action of the heart
The skeletal muscle pump
when the muscles contract and relax they press on nearby veins,causing a pumping effect and squeezing the blood towards the heart
The respiratory pump
when the muscles contract and relax during inspiration and expiration, pressure changes occur in the thoracic and abdominal cavities. These pressure changes compress the nearby veins and assist blood return back to the heart
Pocket valves
These prevent the back flow of blood
Smooth muscles
a thin layer of smooth muscle within the veins helps squeeze blood back towards the heart
Gravity
helps the blood return to the heart from the upper body
Graphs for maximal and sub maximal exercise
Cardiac hypertrophy
The thickening of the muscular wall of the heart so it becomes bigger and stronger ; also can mean a larger ventricular cavity
Bradycardia
A decrease in resting heart rate to below 60 beats per minute.
Cardiac output in response to exercise
During exercise there is a large increase in cardiac output due to an increase in heart rate and an increase in stroke volume. Cardiac output will increase as the intensity of exercise increases
How does a trained performer have a greater heart rate range ?
their resting heart rate is lower and their maximum heart rate increases.
The impact of physical activity and sport on the health of the individual
Decreases the chance of :
Heart disease
High blood pressure
Cholesterol levels
Stroke
Atherosclerosis
Occurs when arteries harden and narrow as they become clogged up by fatty deposits.
Atheroma
A fatty deposit found in the inner lining of an artery.
Angina
Chest pain that occurs when the blood supply through the coronary arteries to the muscles of the heart is restricted.
Stroke
A stroke occurs when the blood supply to the brain is cut of.
Steady state
Where the athlete is able to meet the oxygen demand with the oxygen supply
What is cardiovascular drift?
- After 10 mins of exercise in a warm environment
-You begin to sweat which causes fluid from plasma to be lost
This causes stroke volume to decrease and heart rate to increase
Results in a progressive rise in cardiac output . - this reduces venous return
What do you do as an athlete to minimise cardiovascular drift ?
Maintain high fluid consumption before and during exercise
Blood pressure
The force exerted by the blood against the blood vessel wal.
Systolic pressure
The pressure in the arteries when the ventricles are contracting
Diastolic pressure
The pressure in the arteries when the ventricles are relaxing
Bohr shift
When an increase in blood carbon dioxide and a decrease in pH results in a reduction of the affinity of haemoglobin for oxygen.
Vascular shunt mechanism
The redistribution of cardiac output
Vasodilation
The widening of the blood vessels to increase the flow of blood into the capillaries
Vasoconstriction
The narrowing of the blood vessels to reduce blood flow into the capillaries
Arterie-venous difference
The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles
