Cardiovascular System Flashcards
What are the TWO functions of the cardiovascular system?
Transportation and regulation
What are the THREE parts of transportation?
- Respiratory
- Nutritive
- Excretory
What is the excretory part of the transportation doing?
Cardiovascular system carry metabolism wastes to kidneys to be excreted
What are the FOUR parts of the Regulation?
- Hormonal
- Temperature
- Protection
- Immune
What part of the heart supplies the Pulmonary circuit?
Right hand side
What part of the heart supplies the Systemic circuit?
Left hand side
Is the blood oxygenated or deoxygenated when it enters the lungs?
Deoxygenated
How many chambers are in the heart?
4
What are the chambers of the heart called?
Atria (top) & Ventricles (bottom)
What ventricle delivers blood to the tissues?
Left ventricle
What are the functions of the valves?
To allow unidirectional blood flow and to avoid back flow
What is the name of the valve between the RIGHT atrium and RIGHT ventricle?
Tricuspid valve
What is the name of the valve between the LEFT atrium and LEFT ventricle?
Bicuspid valve
What generates heart pumping action?
Rhythmic contraction and relaxation
Do atria and ventricles contract as a unit respectively?
Yes.
Atria contract as a unit
Ventricles contract as a unit
What drives blood flow?
Pressure gradient
What comes first, atrial or ventricular contraction?
Atrial
What type of tissue is the Atrioventricular valve made of?
Connective tissue
Where are the Semilunar valves located?
At the origin of the aorta and pulmonary artery
What are the TWO proteins arranged in sarcomeres in cardiac muscle?
Actin & Myosin
How do the proteins in cardiac muscle contract?
Via sliding filaments
What joins myocardial cells?
Intercalated discs which contain gap junctions
What are Gap Junctions?
Fluid filled channels that allow action potentials to spread rapidly
What is used to initiate contraction in myocardial cells?
Extracellular Ca2+
What nerves innervate skeletal muscle?
Somatic motor nerves
What generates action potentials?
Depolarisation of the cell
Where are Autorhythmic / Pacemaker cells located?
In the sinoatrial node
(in right atrium near vena cava opening)
What are HCN channels?
Leaky channels that allow spontaneously slow flowing of Na+ and Ca2+ ions
What is the change in membrane potential caused by HCN?
From -60mV to -50mV
When does threshold occur in myocardial autorhythmic cells?
When membrane reaches -50mV
At what voltage do K+ channels open for depolarisation?
At -20mV
When does myocardial contractile cell relaxation occur?
During repolarisation when Ca2+ is transported out of the cell
What activates the cross bridge cycle (muscle contraction)?
Binding of Ca2+ to Troponin
How fast are action potentials in skeletal muscles?
20msec
How fast are action potentials in myocardial cells?
250msec
Are myocardial cells refractory during almost their entire contraction?
Yes
Which node sets the rate of depolarisation of the contractile myocardial cells?
Sinoatrial (SA) node
Which node sets the rate of contraction?
Sinoatrial (SA) node
Which node determines the heart rate?
Sinoatrial (SA) node
Why can’t action potentials spread directly from the atria to the ventricles?
Due to fibrous layer separating both regions
How are action potentials passed from the atria to the ventricles?
- Electrical impulse spreads through atria and reaches AV node
- Passes onto the Bundle of His
- Passes down interventricular septum
- Joins with Purkinje Fibres which conducts activity into ventricles
What causes atrial and ventricular contraction to occur sequentially?
Delay in conduction at AV node
What triggers contraction in myocardial contractile cells?
Increase in intracellular Ca2+
What do electrocardiograms measure?
Movement of electrical activity around the heart
What are the THREE waves during a cardiac cycle?
- P wave - atrial depolarisation
- QRS wave - ventricular depolarisation
- T wave - ventricular repolarisation
What is Systole?
Contraction phase
What is Diastole?
Relaxation phase
What do systole and diastole alone refer to?
Ventricular contraction and relaxation
What vein fills the left atrium?
Pulmonary vein
What vein fills the right atrium?
Vena cava
Does blood volume change during isovolumetric contraction phase?
No
What is Stroke Volume?
Two thirds of blood volume that ventricles contain are ejected into aorta/pulmonary artery
What happens to the heart valves in isovolumetric relaxation?
Both atrioventricular and semilunar valves are closed
How long does diastole last?
0.5 sec