Cardiovascular Flashcards
What are the 3 basic cell types in the heart?
Cardiac muscle cells, purkinje cells and nodal cells.
What are cardiomyocytes composed of and how are they connected to each other?
They majority of them are composed of myofilaments and mitochondria, and joined together by intercalated discs.
List the 3 types of basic cell types located in the heart in terms of decreasing propagation velocity.
Purkinje cells = 120cm/sec
Cardiomyocytes = 70cm/sec
Nodal cells = 20cm/sec
Where are nodal cells located? And how are they connected to each other
The two nodes in the heart: SAN & AVN
They are connected via gap junctions
Define ‘inotropic’ and give both exogenous and endogenous examples.
An inotropic substance is something that affects the force of cardiac contraction; positive inotropic agent = increased force of myocardial contraction
Eg catecholamines and digoxin
Define ‘chronotropic’ agents. Name an example.
Substances that affect HR (e.g. adrenaline, atropine)
Define ‘lusitrophy ‘
Rate of myocardial relaxation
Where is the vagus motor nucleus located?
Brainstem; medulla
The vagus nerve (CNX) has parasympathetic control over the CV system; true or false?
True
What receptors do catecholamines use in the heart and what is their effect?
NA & adrenaline use beta1-adrenoceptors in the hearts
Once stimulated, the activity of adenylyl cyclase increase = increased intracellular conc. of cAMP = stimulation of If = increased rate of depolarisation of pacemaker
What receptors does the ACh released from parasympathetic fibres target in the heart and what is their effect?
They use M2-muscarinic receptors
They reduce the activity of adenylyl cyclase = decreases of intracellular conc. of cAMP = decreases of no. Of active Ca2+ channels = decreased hyperpolarisation = activates inwardly rectifying potassium channels
RESULTS IN negative chronotropy and inotropy
Define end diastolic volume
Volume of blood in ventricles before contraction
Define ‘preload’
The end diastolic pressure, which is stretching the wall of the ventricles to their greatest geometrical dimensions
Define stroke volume
Volume of blood ejected from the heart over heart beat
Describe the Frank-Starling mechanism.
A greater EDV would increase the contractile strength of the ventricles (i.e. myocardiocytes) and will increase stroke volume
Increase EDV = increase contractile strength = increase SV
The reason behind this is that the myocardium will be more stretched due to a greater volume, therefore, their increased sacrilege length results in increased sensitivity to Ca2+ = munch stronger contraction
Describe the Anrep effect
Increased arterial pressure (due to vasoconstriction) causes a slow increase in contractility
How much blood runs through the average adult?
5-6L
What proteins are found in blood (plasma)?
Albumins, globulins and fibrinogen
What is the action of albumins in blood?
To help regulate the osmotic pressure to keep blood inside the vessels
What protein in blood is essential for the blood clotting mechanism
Fibrinogen
Define haematocrit and note the difference between the 2 sexes
The number of RBC/erythrocytes an individual possesses. Women have a slightly lower haematocrit of 3.9-5.8x10^12/L compared to Men of 4.5-6.5x10^12/L due to menstruation.
What is the average diameter of a RBC?
7.2micrometers
What are the 2 types of leukocytes in blood?
Agranulocytes and granulocytes
What is a unique characteristic of a neutrophil’s organelles that makes it easier to distinguish in an histology slide?
It’s 2-5 lobed nucleus: the more lobes = more mature
What type of granules are found in platelets and important for coagulation?
Alpha-granules