INCORRECT EXAMPREP Q'S - CARDIOVASCULAR Flashcards
What is the normal duration of a PR interval? (in seconds)
0.12-0.2
What is the first heard sound?
occurs at the beginning of ventricular systole, caused by the closure of mitral & tricuspid valves
Why does the first heart sound have a lower pitch & a longer duration than the second heart sound?
the mitral & tricuspid valves close more gradually than the pulmonary & aortic valves
What vessels have individual smooth muscle cells rather than a continuous tunica media?
metarterioles
Where does the mitral valve lie?
Lies posterior to the sternum at the level of the 4th left CC
If the flux of glucose is observed to be directly proportional to the trans-membrane concentration gradient, what is the likely method of movement?
simple diffusion
How do cells in the SAN discharge?
Spontaneously
What may increased rate of conduction of the SAN result in?
Supraventricular tachycardia
To which receptor does NA bind in order to mediate vasoconstriction?
alpha 1
What do gap junctions allow in cardiac muscle cells?
impulses to travel from one cardiac fibre to another
Which organ receives approx 9% of the cardiac output ? i.e. 430ml/min
Skin
What tissue forms the most superficial layer of the heart?
visceral pericardium
The IVC is formed by the union of the common iliac veins at what vertebral level?
L5
During exercise what happens to the arterioles in the muscles? What does this result in?
they dilate due to local mechanisms (fall in oxygen & increase in CO2 & other metabolites)
it greatly reduces the TPR
What represents the depolarisation of the IV septum from left to right on an ECG?
The Q wave
What is the main characteristic of the excitation contraction coupling process in cardiac muscle that differentiates it from that seen in skeletal muscle?
the AP can last several hundred milliseconds
What do vasa vasorum consist of?
small blood vessels which provide nutrients for the outer regions of the vessel wall
What 5 things does the sympathetic NS do to the CVS?
decreases capacitance increases CO increases SV increases venous return vasocontriction
Do cardiac muscle fibres branch regularly or irregularly?
irregularly
What proportion of Ca ions enter cardiac muscle cells via L type channels in order to induce CICR?
10%
Starling’s law of the heart states that the energy released during contraction depends on the initial fibre length. The amount of stretch of the heart muscle depends on the EDV, which is affected by WHAT?
- The inherent compliance of the muscle
- heart muscle becomes stiffer & less compliant with age & becomes more difficult for the heart to stretch - The Preload or EDP
- the filling pressure of the heart (determined by pressure in great veins)
What does the starling curve show?
That SV increases with EDP until the muscle is overstretched & then the SV begins to fall
What on an ECG represents the depolarisation of the area of the heart near the base?
S wave
Why is the S wave tall?
becasue of the large muscle mass & rapidity of depoarisation
What vessel is an indirect branch of the abdominal aorta?
inferior gluteal as it arises from the internal iliac artery
What is the origin of sympathetic nerves that innervate the nodal tissue & heart muscle?
T1-5