1.1 Cardiovascular system (add more detail) Flashcards
What does the Cardiac conduction system refer to?
How the heart contracts/how the heart creates its own heart beat
List the CCS in order of impulse travel
SA node (sinoatrial node)
AV node (atrioventricular node)
Bundle of HIS
Purkinje fibers
Explain the function of the SA node?
Sinoartial node
- Sends electrical impulses to spread throughout both atria to stimulate atrial systole.
- Initiates all heart beat and detriments heart rate.
- Natural pace maker of the heart.
Explain the function of the AV node?
Atrioventricular node
- Delays the cardiac impulse, from SA node, to ensures the atria have ejected all the blood into the ventricles before ventricles contacts.
- The AV node receives signals from the SA node and passes them onto the Bundle of HIS.
Explain the function of the Bundle of HIS?
The Bundle is divided into left and right bundle branches and into purkinje fibres
-Conduct the impulses to the apex of the heart. The signals are then passed to Purkinje fibers
Explain the function of the Purkinjie fibers?
- Purkinjie fibres spreads signal throughout the ventricular myocardium causing Ventricular systole
Identify and explain the order in which a cardiac impulse travels?
- SA node initiates heart beat and spreads impulse across top two chambers (atria) creating atrial systole.
- AV node delays impulse (0.1sec) from SA node to ensure atria have ejected all blood into ventricles and sends impulse to Bundle of HIS.
- Conducts impulse to the apex of the heart and then sent to Purkinjie fibers.
- Purkinjie fibers cause ventricular systole
Key terms brain dump
Conducts Electrical impulses Systole Diastole Eject CCS Myogenic Symp
What is the term used when the heart is contracting and relaxing
Systole and diastole
Name all the chambers of the heart
Artia (left and right
Ventricles (left and right)
Ventricle (left+right)
What is the first things that happens during a heart beat?
SA node sends impulse across both atriums causing ATRIAL SYSTOLE
How does the heart control the rate at which it beats
SA node sends impulse to create atrial systole. Impulse reaches AV node which delays cardiac impulse to ensure all blood has been ejected out the atria and into the ventricles. Impulse then sent down to Bundle of HIS and conducts into Purkinje fibres. This will achieve ventricular systole.
How do you measure the electrical activity and rhythm of the heart?
ECG: Electrocardiogram
Why is one side of the heart’s walls bigger than the other?
The ventricles of the heart have thicker muscular walls than the atria. This is because blood is pumped out of the heart at greater force from these chambers compared to the atria. Therefore need to withstand higher pressure.
Which chamber in the heart are larger and explain why?
The left ventricle is the biggest chamber as it has to pump blood to the rest of the body (further distance) whereas the right ventricle only pumps to the lungs.
Name the main blood vessels that enter and leave the heart
Aorta, vena cava and pulmonary artery = AWAY
Pulmonary vein = TOWARDS
Which blood vessel brings deoxygenated blood back to the heart?
Vena cava brings deoxygenated blood to right atrium
Which blood vessel delivers oxygenated blood to the heart?
The Pulmonary vein delivers oxygenated blood to the left atrium.
Whats the difference between arteries and veins?
Arteries carry blood AwAy from the heart, and veins carry blood towards the heart.
What is the function of the Aorta?
Leaves the left ventricle with oxygenated blood to the rest of the body
What is the function of the pulmonary artery?
Leaves the right ventricle with deoxygenated blood to the lungs
The heart acts as a _______ forcing blood around the body
The heart acts as a DOUBLE PUMP forcing blood around the body
Name the hearts two circuits
Pulmonary circulation
Systemic circulation
Systemic circulation
Explain the difference between the hearts circulatory systems
Pulmonary circulation: Deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart
Systemic circulation: Oxygenated blood to the body from the heart and deoxygenated blood from body back to heart.
“The cardiac muscle cells in the heart are myogenic” what is meant by this?
Heart muscle is described as being myogenic as the beat starts in the heart muscle itself with an electrical signal in the sinoatrial node (SAN).
CCS ensures that ………. increases during exercise to allow the …….
CCS ensures that ..heart rate.. increases during exercise to allow the working muscles to receive more oxygen.
Explain the functions of the Neural Control Mechanism?
Involves the sympathetic nervous system = stimulates the heart beat faster. Parasympathetic system which returns the heart to its resting level. Both are coordinated by the Medulla of the brain which is the cardiac control centre.
Sympathetic nerve impulses are sent to the SA node and there is an increase in HR.
Parasympathetic nerve impulses so that the heart rate decreases.
What is the Cardiac control center stimulated by?
The cardiac control center is stimulated by chemoreceptors, baroreceptors and proprioceptors and will send impulses through either the sympathetic system to increase HR, or the parasympathetic to decrease HR.
What are the mechanisms which affect the rate at which cardiac impulses are fired?
Neural Control mechanisms:
Chemoreceptors
Baroreceptors
Proprioceptors
Explain the role of chemoreceptors?
Sense chemical changes such as CO2
Describe why chemoreceptors are important during exercise?
During exercise, chemoreceptors detect an increase in CO2. An increase concentration of CO2 in the blood will stimulate the sympathetic nervous system which means the heart will beat faster.
Explain the role of Baroreceptors?
Baroreceptors detect changes in Blood Pressure.
Detect the stretch in the arterial wall caused by changes in blood pressure. Baroreceptors have a set point for blood pressure.
Describe the function of Baroreceptors
An increase/decrease in set BP causes baroreceptors to send signals to the medulla to either increase or decrease heart rate.
Increase in arterial pressure -> increase stretch of the arterial wall -> increase stretch of baroreceptor sensors = decrease heart rate
Decrease In arterial pressure -> decrease stretch of arterial wall -> decrease stretch of baroreceptor sensors = increase heart rate
Why is it important for Baroreceptors to increase heart rate during exercise?
At the start of exercise the baroreceptors set point increases which is important as the body does not want heart rate to slow down as this would negatively affect performance = less oxygen would be delivered to the working muscles.
What are Proprioceptors?
Sensory nerve endings in muscles, tendons and joints that provide info about movement and body position.
Why are Proprioceptors important during exercise?
At the start of exercise they detect increase muscle movements.
These receptors send impulses to the medulla which sends an impulse through the sympathetic nervous system to the SA node to increase hr.
Explain the hormonal control mechanism
The release of the hormone Adrenaline in the blood during exercise is known as hormonal control. Released into the blood and causes the heart to beat faster (fight or flight response). Occurs within 2-3 min of stressful situations. Released by the sympathetic NS which stimulates the SAN resulting in an increase speed and force of contraction = increase cardiac output. Results in more blood being pumped to the working muscles for oxygen replenishment.
What is stroke volume?
The volume of blood pumped out of the heart’s ventricles each contraction
Memory tool: strOke = not enough blood OUT to the brain = vol of blood pumped OUT each contraction
What does stroke volume depend on?
- Elasticity of Cardiac muscles (more the heart can stretch the greater force of contraction)
- Venous return
What is cardiac output?
The volume of blood pumped out the heart ventricles per minute.
Memory tool: oUtpuT = minUT