Cardiology Flashcards
What are the 2 main components of the circulatory system
- ) Plasma (55%)
2. ) Cellular components (45%) (WBC + RBC)
What is Haematocrit?
% of total blood volume that is erythrocytes
What is Plasma?
The fluid component of the blood that contains Proteins such as Albumin, CLOTTING FACTORS such as Fibrinogen, and nutrients
What is included in the cellular component of blood?
- ) Eryhthrocytes
- ) Platelets
- ) Leucocytes
What are leucocytes?
White Blood Cells
Neutrophils Eosinophils Basophils Monocytes T+B cells
What is Serum?
Plasma with Clotting Factors removed
Where do all blood cells descend from?
Multipotent Haematopoietic Stem Cells
What is the precursor to Lymphocytes?
Bone Marrow Precursor Lymphocytes
What is the precursor cell for every blood cell except lymphocytes
Blast Cells
Where are Erythrocytes produced in the Adult?
Bone Marrow in Axial Skeleton
Where are Erythrocytes produced in the foetus?
Yolk Sac
Liver
Spleen
What is the average lifespan of a RBC and where are they removed?
120 days
The Spleen
What do Neutrophils do?
Most Numerous WBC
Phagocytose
What do Eosinophils do?
Kill Parasites
What do Basophils do?
Involved in Inflammation via the secretion of Histamine
What do Monocytes do?
Regulate the Immune Response via secretion of Cytokines
Give way to Macrophages
What do Macrophages do?
Engulf and Ingest
Antigen Presentation
What do T+B cells do
Specific Immune Response
Antibody Production
What are the Granulocytes
Neutrophils
Basophils
Eosinophils
What are the Agranulocytes
T+B Lymphocytes
Monocytes
What is the main factor that influences blood flow?
Pressure
What are the 2 circulations
Pulmonary
Systemic
Stages of the Microcirculation
Arteries -> Arterioles -> Capillaries -> Venules -> Veins
What is Preload?
End Diastolic Volume
What is Afterload?
Pressure in the Aorta that the LV must overcome in order too pump blood around the body
Blood flow is from regions of …. to regions of ….
Higher Pressure to Lower Pressure
Equation for Force of contraction?
Change in Pressure/ Resistance
Forces is Directly Proportional to…
Change in Pressure
Force is indirectly proportional to…
Resistance
What is the main variable that impacts resistance in blood vessels
Diameter of Blood Vessels
What do Gap Junctions do?
Allow action potentials to pass between myocytes
What triggers contraction of Cardiac Muscle?
Depolarisation of Myocyte plasma membrane
Where does the initial depolarisation in the heart occur?
SA Node
Why is the SA node referred to as the ‘Pacemaker of the Heart”
Initial depolarisation occurs there
Sequences of Cardiac Depolarisation
SA Node -> Atrial Contraction -> Internodal Pathways -> AV node -> Bundle of His -> L/R Bundle Branches -> Purkinje Fibres -> Ventricular Contraction
Describe what happens during a Cardiac Myocyte Action Potential?
- ) Na+ channels open; Na+ moves into the cell causing DEPOLARISATION (causes more Na+ channels to open via + feedback)
- ) K+ channels open temporarily, causing momentary repolarisation
- ) Ca++ channels open, balancing out the K+ lost out of the plasma membrane, causing a PLATEAU
- ) Ca++ channels close, whilst more K+ channels open -> REPOLARISATION
Describe the Action Potential in Nodal Cells?
- ) K+ channels close at a - voltage
- ) Ca++ and Na+ channels open at - voltage, causing PACEMAKER POTENTIAL - gradual depolarisation
- ) Once a threshold value has been reached, Ca++ channels open, depolarising the cell and causing an AP
- ) K+ channels open and Ca++ channels close, leading to the formation of a Pacemaker Potential Again
What does the P wave represent?
Atrial Depolarisation
What does the QRS complex represent?
Ventricular Depolarisation
Atrial Repolarisation
What is the T wave?
Ventricular Repolarisation
Describe the Process by which Cardiac Muscle Contracts? (Excitation- Contraction Coupling)
- ) Na+/K+ pump keeps resting potential
- ) Na+ channels open, depolarising the cell
- ) Depolarisation causes Voltage-Gated Ca++ cells to open, causing Ca++ to enter the cell
- ) Ca++ entry causes Ryanodine Receptors to release more Ca++ into the SR
- ) Ca++ binds to Troponin, causing a conformational change in the shape of Troponin, which results in the movement of Tropomyosin away from the Actin-Myosin binding sites
- ) Actin- Myosin cross bridges formed, resulting in muscle contraction
- ) Ca++ is removed back into Ryanodine Receptors by Ca++/ATPase
What are Ryanodine Receptors?
Ca++ gated Ca++ stores found in the SR
What removes Ca++ from the SR following muscle contraction
Ca++/ATPase
How can the strength of cardiac muscle contraction be increased?
Increased concentration of Ca++ in Cytosol
