Lecture 8: The Heart as a Pump Flashcards
What circuit move blood to and from the lungs?
The Pulmonary circuit
What circuit moves blood to and from the tissues of the body?
The Systemic circuit
How many chambers of the heart are there?
Four
How many directions does blood flow in?
One
What direction does arterial blood flow in?
Away from the heart
What direction does Venous fluid flow in?
Towards the heart
How many pumps are in the heart and how can their location be described?
There are 2 pumps and they are in series
When pumping blood which pumps work together in synchronisation?
The left/right
When contracting what contracts first?
Atria
When the heart contracts what contracts second?
Ventricles
What controls the flow of blood between the Atria and ventricles?
Tricuspid and bicuspid (mitral) valves
atrioventricular valves
What controls the flow of blood from the ventricles out to the circulatory vessels?
Aortic and pulmonary valves
Semilunar valves
What are Thin filaments made of?
Actin
What are Thick filaments made of?
Myosin
What causes mysoin-actin cross bridges to form in cardiac muscle?
Calcium levels increasing
Where are calcium ions released from into the cardiac muscle?
Sarcoplasmic reticulum
How do myosin-actin interactions generate force?
Myosin pulls on actin to shorten the sarcomere
What myocytes are activated during each heart beat?
All the Myocytes
How can force be increased during the contractions of the heart?
Increasing the extent of of cross bridge formations
How can the extent of cross bridge formations be increased?
3
- increase cytosolic calcium level
- increase number of cross-bridges formed
- increase force of contraction
What causes cardiac relaxation?
Decrease in cytosolic calcium levels by pumping calcium back into the sarcoplasmic reticulum
What happens to the heart during Diastole?
2
- Relaxes
- Falling pressure
What happens to the heart during Systole?
2
- Contraction
- Rising pressure
What happens during Atrial systole?
- Atria contract moving blood to the ventricles
- AV valves open
- Semilunar valves are closed
What happens in the Isovolumetric ventricular contraction?
5
- Atria relax
- Ventricles contract
- AV valves close
- Semilunar valves close
- Pressure increases
What happens in the Ventricular ejection phase?
- Blood is pushed out of the ventricles
- ventricles contract
- Semilunar valves open
What happens during Isovolumetric ventricular relaxation phase
- Semilunar valves close
- AV valves close
- Pressure decreases
What has a higher pressure systemic or pulmonary circuit?
Systemic
What is diastolic blood pressure?
Your lowest blood pressure
What is systolic blood pressure?
Your highest blood pressure
What is the pulse pressure?
The difference between the diastolic and systolic pressure
What is mean pressure?
The average pressure over a cardiac cycle
Why is the mean pressure lower than half way?
Because we spend more time at diastolic pressure
What is hypertension?
A high blood pressure
What is hypotension?
A low blood pressure
What is the equation for flow?
Flow = Pressure difference / Resistance
Which circuit has a higher resistance?
Systemic circuit
