The Cardiovascular System Flashcards
What is the cardiovascular system?
Its the body’s transport system. It includes the heart and the blood vessels.
What are the functions of the cardiovascular system?
Carries oxygen + nutrients
Gets rid of carbon dioxide
Regulates body temperature
Protects the body
What are the chambers of the heart?
It’s divided into two parts by a muscular wall called the septum and each part contains two chambers - an atrium and a ventricle.
What do the atria do?
They’re smaller than the ventricles as all they do is push the blood down into the ventricles.
They have thinner muscular walls
What do the ventricles do?
They have much thicker muscular walls as they need to contract with greater force in order to push blood out of the heart.
What side of the heart is bigger?
The left, as it needs to pump blood all around the body.
Whereas the right pimps deoxygenated blood to the lungs which are in close proximity to the heart.
What blood vessels are connected to the heart?
The vena cava
Pulmonary vein
Pulmonary artery
Aorta
What does the vena cava do?
Brings deoxygenated blood back to the right atrium.
There’s the superior (top) and inferior (bottom)
What does the pulmonary vein do?
From the lungs - Delivers oxygenated blood to the left atrium.
What does the pulmonary artery do?
Leaves the right ventricle with deoxygenated blood to go to the lungs
What does the aorta do?
Leaves the left ventricle with oxygenated blood leading to the body.
How many valves are in the heart and what are they called?
There are 4 main valves
The tricuspid valve
The bicuspid valve
The semi-lunar valves - pulmonary and aortic
Where is the tricuspid valve?
Between the right atrium and right ventricle.
Where is the bicuspid valve?
Between the left atrium and left ventricle
Where are the semi-lunar valves?
Between the right and left ventricles and the pulmonary artery and aorta.
What is the cardiac conduction system?
A group of specialised cells located in the wall of the heart which send electrical impulses to the cardiac muscle, causing it to contract.
What is the Sinoatrial node (SAN)?
A small mass of cardiac muscle found in the wall of the right atrium that generates the heartbeat.
Commonly known as the pacemaker.
What does myogenic mean?
The capacity of the heart to generate its own impulses
What is the atrioventricular node (AVN)?
Found in the atrioventricular septum.
It relays the impulse between the upper and lower sections of the heart.
What is systole?
When the heart contracts.
What is the bundle of His?
A collection of heart muscle cells that transmit electrical impulses from the AVN bias the bundle branches to the ventricles.
What are Purkinje fibres?
Muscle fibres that conduct impulses in the walls of the ventricles.
What’s the order that blood passes through the heart?
Vena cava Right atrium Tricuspid valve Right ventricle Pulmonary artery Lungs Pulmonary vein Left atrium Bicuspid valve Left ventricle Aorta Body
What does the SAN do?
Regulates heart at 60-100 bpm
Generates the heartbeat using electrical impulses
Bachman’s branch carries them to the left atrium
Impulses cause atrial systole.
What does the AVN do?
Delays transmission of the cardiac impulse for approximately 0.1 seconds.
This enables the atria to fully contract before ventricular systole begins
Regulates heart at 40-60 bpm.
What does the bundle of His do?
The electrical impulse travels through these fibres
Located in the septum, separating the two ventricles
It branches out into two bundle branches called Purkinje fibres.
They go around the ventricles and cause them to contract
Regulates heart at 20-40 bpm
What does the conduction system ensure?
It ensures that heart rate increases during exercise to allow working muscles to receive more oxygen.
What factors affect the change in rate of the conduction system?
The rate in which cardiac impulses are fired can be controlled by 3 main mechanisms:
Neural control mechanism
Receptors
Hormonal control mechanisms
What is the neural control mechanism?
It involves the sympathetic nervous system and the parasympathetic system. The nervous system is made up of two parts: the central nervous system and the peripheral nervous system. These two systems are coordinated by the cardiac control centre located in the medulla oblongata of the brain.
Sympathetic nervous impulses are sent to the SAN and there is a decrease in parasympathetic never impulses so that the heart rate increases
What is the sympathetic nervous system?
A part of the autonomic nervous system that speeds up heart rate
What is the parasympathetic system?
A part of the autonomic nervous system that decrease heart rate.
What is the medulla oblongata?
It regulates processes that keep us alive such as breathing and heart rate.
What is the types of receptors involved with conduction system?
Chemoreceptors
Baroreceptors
Proprioceptors
What are chemoreceptors?
Tiny structures in the carotid arteries and aortic arch that detect a change in blood acidity cause by an increase or decrease in the concentration of carbon dioxide.
What do chemoreceptors do during exercise and how?
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.
What are 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.
What do baroreceptors do during exercise and how?
At the start of exercise the baroreceptor set point increases, which is important as the body doesn’t want heart rate to slow down as this would negatively affect performance, as less oxygen would be delivered to the working muscles.
What do baroreceptors do?
They establish a set point for blood pressure.
An increase/decrease above/below this point results in baroreceptors sending signals to the medulla in the brain.
An increase in arterial pressure causes an increase in the stretch of the baroreceptor sensors and results in a decrease in heart rate.
What are proprioceptors?
Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement.
What do proprioceptors do during exercise and how?
At the start of exercise, they detect an increase in muscle movement.
These receptors then send an impulse to the medulla, which sends an impulse through the sympathetic nervous system to the SAN to increase the heart rate.
When the parasympathetic system stimulates the SAN, heart rate decreases.
What’s the hormonal control mechanism?
Hormones can also have an effect on heart rate.
The release of adrenaline during exercise is known as hormonal control.
What is adrenaline?
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in heart rate.
How does adrenaline effect heart rate?
Its stimulates the SAN (pacemaker) which results in an increase in both the speed and force of contraction, thereby increasing cardiac output.
This results in more blood being pumped to the working muscles so they can receive more oxygen for the energy they need.
What is stroke volume?
The volume of blood pumped out by the heart ventricles in each contraction.
Average resting stroke volume is approximately 70ml.
What does stroke volume depend on?
Venous return.
The elasticity of cardiac fibres.
The contractility of cardiac tissue (myocardium).