Electrical Impulse of the Heart
Where is the sino-atrial node located?
Right Atrium
What does the aorta do?
Carry blood away from the heart to the rest of the body
What does atrial systole mean?
The contraction of the atria
What is an antigen?
A protein on the surface on the membrane of a cell
What does the SAN do?
It is the pacemaker of the heart - it sends electrical impulses to the AVN and to atrial walls making the atria contract
What blood vessel carries blood from the lungs into the heart?
Pulmonary Vein
What does the QRS complex on the electrocardiogram signify?
Ventricular depolarisation - ventricles begin to contract
What attacks antigens?
Antibodies
How does the electrical impulses travel down from the AVN to reach the apex of the heart?
Travels down the Bundle of His
What are two examples of arrhythmias?
Tachycardia, Bradycardia, Sinus Arrhythmia, Ventricular Fibrillation and Flat Line.
What are the three stages in the cardiac cycle?
1 - Atrial Systole
2 - Ventricular Systole
3 - Cardiac Diastole
What blood group is know as a universal recipient and why?
AB because it has no antibodies in their blood plasma so would not attack the donor's antigens
What does the electrical impulse travel along to make the ventricle walls contract?
The Purkinje Fibres
What are the 2 types of medications used to treat CVD and how do they work?
Antihypertensives - lower blood pressure
Statins - lower blood cholesterol
At which stage in the cardiac cycle do semi-lunar valves open?
During ventricular systole when pressure in the ventricle becomes higher than in the aorta and pulmonary artery
What blood group is know as a universal donor and why?
O because it has no antigens on its surface so the recipient's antibodies would not attack the O blood cells
Why is there a time delay at the AVN before sending the electrical impulse down the Bundle of His?
To ensure that atria have fully contracted and pushed all the blood down into the ventricle
Why is the circulatory system called a double circulatory system?
One side of the heart pumps blood around the whole body - systemic circulation - whilst the other side pumps blood to the lungs for gas exchange - pulmonary circulation
The P wave signifies which stage of the cardiac cycle?
Atrial Systole because the atria are contracting due to atrial depolarisation
Why can an O+ donor NOT give blood to an O- recipient?
Because O+ has D antigens and O- have anti-D antibodies so the recipient's antibodies would attack the donors O- red blood cells.