Cardiovascular Flashcards
What is the muscular ridge found between the atria?
Crista terminalis
What is the fossa ovalis a remnant of?
Foramen ovale in foetal heart
Shunt to bypass lungs
RA
What are trabeculae carnae?
Irregular muscular elevations in the inflow part of the ventricles
What are attached to the tricuspid/mitral valves to prevent prolapse? (2)
Papillary muscles & chordae tendineae
What is the route the blood takes through systemic & pulmonary circulation?
Body > IVC/SVC > RA > tricuspid valve > RV > pulmonary valve > pulmonary arteries > lungs > pulmonary veins > LA > mitral valve> LV > aortic valve > aorta > body!
What is the superior vena cava formed from?
The merging of the brachiocephalic veins
At what level does the IVC enter the thorax?
T8
Give the 5 branches of the aortic arch, and the bifurcation of one of these branches
R & L coronary arteries
Brachiocephalic trunk (bifurcates into R subclavian & R common carotid arteries)
L common carotid artery
L subclavian
What are the 3 main layers of the heart wall from innermost to outermost?
Endocardium
Myocardium
Epicardium
What does the L coronary artery split into?
LAD
LMA
LCxA
What does the R coronary artery split into?
PIvA
RMA
What artery supplies the AVN & SAN?
RCA
What does the superior mediastinum contain?
Arch of aorta
SVC
Phrenic nerve
Vagus nerve
What is the inferior border of the superior mediastinum?
The level of the sternal angle
What is referred pain?
Pain perceived at a location other than at the site of the painful stimulus
What is the referred pain for the heart?
Jaw
L shoulder
L arm
Back
What are the 2 layers of the pericardium?
Fibrous (external)
Serous (internal)
What are the 4 functions of the pericardium?
Limits motion
Prevents overfilling
Provides lubrication
Protection from infection
What is systole?
The ventricular contraction phase
What does the ECG mean in terms of depolarisation of the heart?
P wave: depolarisation of atrium
QRS complex: depolarisation of ventricle
T wave: repolarisation of ventricle
What are the 5 stages of the cardiac cycle?
- Atrial systole
- Isovolumetric contraction
- Ventricular ejection
- Isovolumetric relaxation
- Ventricular filling
What is Starling’s law of the heart?
SV of the heart will increase in response to an increase in EDV when all other factors remain constant
Explain Starling’s law of the heart
The sarcomeres stretch more when the ventricle is more full (EDV increased)
There is more ability to contract more
Due to increased venous return
Give an equation that links HR, SV & CO
CO = HR x SV
Describe the length-tension relationship
As the length of the sarcomeres increases, contraction is stronger
Until the filaments are separated completely - no contraction can then take place
What is the neurotransmitter of the parasympathetic NS?
Acetylcholine
What is the area where there are no thick filaments in a sarcomere?
I-band
Give the 4 stages of the sliding-filament theory of muscle contraction
Cross bridge binds to actin
Cross bridge moves actin by releasing ADP & Pi
ATP binds to cross bridge causing it to detach
Hydrolysis of ATP
What molecule blocks the binding sites on actin?
Tropomyosin
What molecule holds tropomyosin in place?
Troponin
What causes tropomyosin to move from its blocking position?
Calcium ions
What are the steps of excitation-contraction coupling?
Action potential propagated down plasma membrane of T-tubules
Voltage-gated channels open - small Ca2+ influx
Ca2+ binds to ryanodine receptors on sarcoplasmic reticulum
Channels open, releasing calcium storage
What are the 6 layers of arteries/veins from innermost?
Lumen Tunica intima Internal elastic lamina Tunica media External elastic lamina Tunica adventitia
What property of large arteries has the biggest impact on blood pressure?
Stretch/recoil
Give an equation relating MAP, CO, TPR
MAP = CO x TPR
Give an equation for MAP
MAP = DP + 1/3 (SP - DP)
DP diastolic pressure
SP systolic pressure
Give an equation for pulse pressure
PP = SP - DP
What nerve is the heart rate controlled by?
Vagus, sympathetic
Where are 2 main baroreceptors found?
Carotid sinus
Aortic arch
What do chemoreceptors respond to?
CO2
O2
H+
What is Ohm’s law?
Flow rate is directly proportional to pressure difference
Flow rate is inversely proportional to resistance
What is Poiseulle’s law?
Resistance is directly proportional to the viscosity of the fluid
Resistance is inversely proportional to the radius of the vessel
What is an autocrine substance?
A substance thats effects are on the cell by which it was secreted (local control)
What are 2 extrinsic controls of TPR?
Hormonal
Neural
What does NO do to blood vessels?
Vasodilates
What does adrenaline bind to to cause vasoconstriction/dilation?
Vasoconstriction - alpha-adrenergic receptors
Vasodilation - beta-2-adrenergic receptors
What are the 12 ECG leads?
I, II, III
aVR, aVL, aVF
V1, V2, V3, V4, V5, V6
Describe the conduction pathway
SAN AVN (delays) Interventricular septum Bundle of His L & R branches Purkinje fibres Cells Impulse
What are the phases of the cardiac myocyte action potential?
Phase 4: negative membrane potential; Na+K+ATPase pump pumps Na+ out & K+ in; K+ leak out
Phase 0: adjacent cell undergoes depolarisation; Na+ & Ca2+ diffuse into cell via gap junctions; Na+ channels open: Na+ flood in; depolarisation of cell
Phase 1: Na+ channels close; K+ channels open; K+ diffuse out; partial depolarisation
Phase 2: Ca2+ channels open; Ca2+ diffuse in (counteract effect of K+ leaving); plateau
Phase 3: Ca2+ channels close; K+ continues to leave; repolarisation
What is the product of the breakdown of erythrocytes?
Bilirubin
What stimulates RBC development from unspecialised cells?
EPO, a hormonal growth factor
What are the 5 types of leukocyte?
Eosinophil (PMG, fights infections)
Basophil (PMG, secrete histamine & anticlotting factor)
Neutrophil (PMG, phagocytes)
Monocyte (develop into macrophages)
Lymphocyte (immune role, B & T main types)
Describe the steps of platelet plug formation
Connective tissue collagen fibres are exposed
van Willebrand factor (produced by platelets & endothelial cells) binds to collagen fibres
vWf shape changed
vWf can now bind to platelets
Forms bridge between collagen & platelets
Platelets release the contents of their vesicles
What is platelet aggregation?
Some changes cause platelets still in the bloodstream to bind to platelets already bound to collagen fibres
What does platelet aggregation stimulate?
Platelets to synthesis Thromboxane A2, which is released into the ECF and further stimulates platelet aggregation & release of the contents of their vesicles
What is platelet contraction?
This aids sealing of the plug
Platelets contain large amounts of myosin & actin
Compress & strengthen plug
What prevents the platelet plug from continuously expanding?
Intact adjacent epithelium produces prostacyclin & NO
What is blood coagulation?
The transformation of blood into a solid gel made primarily of fibrin
What are the 3 main actions of thrombin?
Converts fibrinogen to fibrin
Catalyses the conversion of factors V, VIII, XI to their active forms
Activates platelets
What type of antibodies do people with type A erythrocytes have in their plasma?
Anti-B
What epithelium lines blood & lymph vessels?
Simple squamous
What are the chambers of the heart lined by?
Endocardium
State 5 metabolic or physiological factors that reduce peripheral vascular resistance
Nitric oxide/metabolic breakdown products, Hypoxia, Hypercapnia, Reduced sympathetic stimulation, Parasympathetic stimulation
