Cardiovascular Flashcards
the pulmonary valve is
between right ventricle and pulmonary artery
the aortic valve is
between left ventricle and the aorta
right atrium receives deoxygenated blood from
IVC/SVC/coronary sinus
left atrium receives oxygenated blood from
right and left pulmonary veins
anterior/sternocostal surface of heart
mostly R ventricle
inferior/diaphragmatic surface of heart
mostly L ventricle
posterior surface/base of heart
L atrium + pulmonary veins
apex of heart
L ventricle
right border of heart consists of
right atrium
inferior border of heart consists of
L ventricle + R ventricle
left border of heart consists of
L ventricle (some of L atrium)
superior border of heart consists of
R/L atria and great vessels
surface marking for apex of heart
mid-clavicular line
5th intercostal space
auscultation of mitral valve
apex
auscultation for tricuspid valve
left lower sternal border 5th intercostal space
auscultation for pulmonary valve
left of sternum 2nd intercostal space
auscultation for aortic valve
right of sternum 2nd intercostal space
the first heart sound (S1) is
the closing of tricuspid/mitral valves at beginning of systole
the second heart sound (S2) is
the closing of aortic/pulmonary valves at beginning of diastole
superior mediastinum contains (5)
arch of aorta - 3 branches superior vena cava - 4 tributaries vagus nerve phrenic nerve thymus/trachea/oesophagus etc
middle mediastinum contains (6)
heart pericardium bifurcation of trachea origins of great vessels cardiac plexus phrenic nerves
what is the floor of the inferior mediastinum
the diaphragm
posterior mediastinum contains (5)
oesophagus descending aorta - branches azygous veins sympathetic nerve trunks thoracic splanchnic nerves
where does the right coronary artery arise from
anterior aortic sinus and runs in coronary sulcus
what does the right coronary artery supply
SAN
AVN
R atrium/R ventricle
where does the left coronary artery arise from
left posterior aortic sinus and divides in the atrioventricular groove
dominance refers to
70% people RCA supplies PDA
20% co-dominant from RCA and Cx
10% Cx supplies PDA
right marginal artery supplies
right ventricle and apex
left anterior descending supplies
R ventricle L ventricle and interventricular septum
left marginal artery supplies
left ventricle
left circumflex artery supplies
left atrium left ventricle
why are LV walls x3 thicker than RV
increased resistance of systemic circulation compared to pulmonary circulation
brachiocephalic trunk landmark
second right costal cartilage
the pericardium consists of
fibrous layer
serous layer= parietal and visceral
what is the pericardial cavity
space between parietal and visceral layers
mneumonic for pericardium
fart police smell villains
where is the oblique sinus
pericardial space behind the left atrium
what is the blood supply of the pericardium
pericardiacophrenic arteries
internal thoracic arteries
what innervates the pericardium
phrenic nerve
what supplies parasympathetic innervation of the heart
the vagus nerve
what supplies sympathetic innervation of the heart
sympathetic trunk via cardiac nerves
what provides motor innervation to the diaphragm
phrenic nerve
why do we get referred pain from heart damage
pain felt in cutaneous regions because dermatomes responsible for cutaneous pain are supplied by same spinal cord levels as visceral afferents from the heart
where is pain felt during myocardial infarction
right shoulder region
what are the nerve roots of the phrenic nerves
anterior rami of C3 C4 C5
what structures are supplied by the vagus nerve (6)
pharynx larynx heart lungs foregut midgut
left common carotid artery supplies
most of cerebral hemisphere + L face and neck
left subclavian artery supplies
vertebral
thyrocervical
axillary arteries
what supplies the SAN
60 % people RCA
40% people LCA
what supplies the AVN
posterior descending artery
what is haemocrit
the percentage of RBCs in the cellular component of blood
components of blood proportions are
45% cellular
55% fluid
45% haemocrit
where are erythrocytes formed in adults
bone marrow in axial skeleton
where are erythrocytes formed in children and foetuses
bone marrow in bones in children
liver/yolk sac/bone marrow in foetus
what is the erythrocyte regulatory hormone
erythropoietin
5 types of leukocytes
eosinophil neutrophil basophil monocyte lymphocyte
eosinophil characteristics
bilobed nucleus
upregulated in parasitic infection
decrease histamine
bright pink/orange granules
neutrophil characteristics
most abundant
multilobed nucleus - increase with age
granular cytoplasm
acute inflammation/phagocytic function
basophil characteristics
bilobed nucleus
dark blue granules fill cell
precursor to mast cells
contain histamine = allergic response
monocyte characteristics
kidney shaped nucleus
pale blue cytoplasm
differentiate into dendritic cells/macrophages
adaptive immunity
lymphocyte characterists
fried egg appearance
B or T cells
immature = bigger than RBC
B lymphocytes become
plasma and produce antibodies
what do T cells do
mediate inflammation
platelet features
anucleate and discoid
stain blue
4 types of granules
where are platelets formed
from megakaryocytes in the bone marrow
platelet life span
5-10 days
platelet regulatory hormone
thrombopoietin
name 4 soluble plasma proteins
albumin
carrier proteins
coagulation factors
immunoglobulins
what is haemostasis
maintenance of balance of blood flow so it is liquid in vessels but clot outside
what allows blood to stay liquid
coagulation factors and platelets are INACTIVE
what activates platelets
tissue factor found on all cells except endothelial cells
what happens when you cut yourself
vessel damage leads to vessel constriction
slow of blood flow to area and endothelial surfaces press together
bleeding is stopped by platelet plug and coagulation cascade
formation of platelet plug 5 steps
- endothelium disrupted = expose collagen fibres
- platelets adhere to VWF which is bound to collagen
- binding causes release of dense granules and thrombin form platelet
- platelet is activated = spiculated shape
- fibrinogen binds to platelets to allow more platelets to aggregate
what does the release of platelet dense granules do
causes platelet amplification
what does the release of thrombin do
platelet activation and further thrombin release via positive feedback
how does the platelet plug stay where its wanted
prostaglandins produced by undamaged endothelium = inhibit aggregation
nitric oxide from undamaged endothelium = vasodilation and inhibit aggregation
why do we have a coagulation cascade
occurs around platelet plug to support and reinforce
what enzyme converts prothrombin to thrombin
clotting factor Xa
what is the role of thrombin enzyme
convert soluble fibrinogen to insoluble fibrin
fibrinolytic pathway
plasminogen converted to plasmin to break down fibrin
what level is the arch of the aorta
T4
type A have
A antigen on surface of RBC and anti-B antibodies in plasma = co-dominant
type B have
B antigens on surface of RBC and anti-A antibodies in plasma = co-dominant
type AB have
A and B antigens on surface of RBC but no anti-A or anti-B in plasma = universal recipient
type O have
no A or B on surface of RBC but BOTH anti-A and antiB antibodies in plasma = universal donor
what is rhesus
C, D, E antigens
what is rhesus postivie
D antigen present
what is rhesus negative
D antigen NOT present
what is rhesus sensitisation in pregnancy
mother has RhD negative baby has positive
mothers blood recognises as foreign = makes antibodies against
takes time so 1st baby unaffected but mother = sensitised to RhD positive blood
what is rhesus disease
mother has antibodies against RhD positive baby
attacks baby RBC
causes anaemia and jaundice
4 features of a cardiac myocyte
intercalated discs
centrally nucleated
striated
branching
what is systole
isovolumetric ventricular contraction and ventriucular emptying (not completely)
0.3 secs
what is diastole
isovolumetric ventricular relaxation and ventricular filling
0.5 secs
isovolumetric definition
change in pressure but not in volume
what is responsible for 80% ventricular filling
rapid ventricle filling - rest is slow filling due to equalising pressures
what is diastis
little to no net movement of blood
what is atrial booster
sudden pressure increase due to atrial contraction (SAN) allowing ventricles to be actively filled
what is the length of a cardiac cycle
0.8 secs
what is starling’s law
the larger the volume of the heart the greater the energy of its contraction and amount of chemical change at each contraction
larger end diastolic volume = larger stroke volume
what is compliance
relationship between change in stress and the resultant strain e.g. how easily blood chamber expands when filled with blood
what is diastolic distensibility
pressure required to fill the ventricle to the same diastolic volume
what is elasticity
myocardial ability to recover its normal shape after removal of systolic stress
parasympathetic stimulation of the heart casues
decrease heart rate
decrease force of contraction
decrease CO
sympathetic stimulation of heart causes
increase heart rate
increase force of contraction
increase CO
myosin structure
2 heavy chains and 2 light chains
what is actin
polymerised globular protein with troponin and tropomyosin
what is titin
elastic filaments that maintain sarcomere alignment
molecular sarcomere contraction 4 steps
- action potential inhibits calcium pumps = calcium escape from sarcoplasmic reticulum
- calcium binds to troponin = changes shape so moves tropomyosin to expose myosin binding site on actin
- myosin head bind to actin bridges formed = ADP released = myosin head move forward = contraction
- energy from atp pulls z lines closer together = contraction
- ATP attach to myosin head = breakdown of bridges
where are calcium ions stored
sarcoplasmic reticulum
what is excitation-contraction coupling
- motor neuron connect with muscle at neuromuscular junction
- Acetylcholine diffuse along synaptic cleft depolarise sarcolemma
- depolarisation = Ca2+ released to stimulate contraction
pressure of pulmonary circulation
20/8
pressure of systemic circulation
120/80
what constitutes microcirculation
arterioles capillaries and venules
artery features
thick muscular wall to sustain force of LV contractions
elastic for systole
diastolic pressure supplies elastic recoil
arteriole features
smooth muscle walls
site of resistance to vascular flow
determines arterial pressure
distributes flow to tissues/organs
capillary features
endothelial cells and pericytes
fenestrated
what is the role of precapillary sphincters
control blood flow to tissue
what happens to substances and fluid that move into tissue
it becomes lymph
how much of total blood do veins hold
70%
3 functions that allow venous return against gravity
valves prevent backflow
muscle action peristalsis
respiratory pump
lymph vessels features
low pressure valves drains excess fluid from tissues no RBC/large proteins but all other blood components fluid is eosinophilic
where does lymph drain
subclavian veins
stroke volume equation
end diastolic volume - end systolic volume
cardiac output equation
heart rate x stroke volume (typically 5L/min)
blood pressure equation (BP)
CO x total peripheral resistance
pulse pressure equation (PP)
systolic - diastolic pressure
mean arterial pressure (MAP)
diastolic pressure + 1/3rd pulse pressure
Ohm’s Law, force =
pressure gradient / resistance
what is the end systolic volume
volume of blood left in ventricle after contraction
what is the end diastolic volume
volume of blood in ventricle before contraction (how much filled)
Poiseuille’s equation, flow =
radius of blood vessel to power of 4
what does PACE stand for
preload
afterload
contractility
‘eart rate
preload definition
volume of blood in LV which stretches cardiac myocytes before LV contraction
what happens if preload increases
increased end diastolic volume
myocardial fibres stretch more
increase force of contraction = starling
increase stroke volume
afterload definition
pressure LV must overcome to eject blood during contraction
what happens of afterload increases
decreases stroke volume
increase venous return would cause
increase EDV
increase stretch of muscle
increase force of contraction
increase stroke volume and cardiac output
what is contractility
the force in which the heart contracts
independent of load and reliant on sympathetic innervation/hormonal factors
increase contractility would cause
heart contracts with more strength = higher pressure
what is vascular resistance
resistance that must be overcome to push blood through the circulatory system
which cells are auto-rhythmic
pacemaker cells
which cells are non-autorhythmic
cardiac contractile cells
which clotting factors is vitamin K necessary for
2, 7, 9, 10
remember as 1972
cardiac myocyte action potential 6 steps
- action potential from adjacent cells = Na+ into cells = rapid depolarisation
- opens K+ channels = K+ out of cell = partial repolarisation
- Ca2+ channels open and enter = plateau
- Ca2+/Na+ channels close only K+ open and moving out = repolarisation
- resting potential maintained
3 differences between cardiac action potential and regular action potential
cardiac = calcium leaving cell causes a plateau cardiac = 200-300ms vs 1ms cardiac = longer refractory period
why does cardiac action potential have a longer refractory period
to prevent muscle fatigue
pacemaker action potential
- HCN channels allow Na+ in = depolarisation
- threshold is -40mV
- Ca2+ voltage gated channels = calcium in = even more positive
- too positive = K+ open and exit = repolarisation
- resting potential restored
why does the SAN determine the pace of the heart
because resting potential is closer to threshold = action potential initiated more rapidly than in AVN
speed of transmission through pacemaker cells is
slower than through cardiac myocites because in pacemaker Ca2+ used to depolarise = slower
sympathetic stimulation of pacemaker action potential
adrenaline/noradrenaline bind to Beta1 = increase Na permeability so threshold reached faster
parasympathetic stimulation of pacemaker action potential
acetylcholine bind to muscarinic receptor = decrease Na permeability so threshold reached slower
what regulates peripheral resistance
vasoconstriction/vasodilation
autonomic NS - sympathetic = constriction
blood viscosity
MAINLY ARTERIOLE RESISTANCE
3 types of vasoconstrictors and examples
local = endothelin 1 hormonal = adrenaline/angiotensin 2/ADH medulla = pressor region
role of pressor region
increases blood pressure by increasing vasoconstriction = increase cardiac output
name 7 local causes of vasodilation
NO H+ lactic acid hypoxia increased CO2 bradykinin prostaglandin/prostacyclin
3 hormonal vasoconstrictors
angiotensin 2, vasopression, adrenaline
medulla source of vasodilation is
depressor region = inhibits pressor region
where are central baroreceptors located
atria
ventricles
pulmonary artery
role of central baroreceptors
inhibit pressor region
RAAS
ADH if increased pressure
= decrease BP
where are central chemoreceptors located
in the medulla
role of central chemoreceptors
respond to changes in pH as CO2 cant cross BBB
where are peripheral baroreceptors/chemoreceptors located
aortic arch (vagus nerve) carotid sinus (glossopharyngeal nerve)
role of peripheral chemoreceptors
stimulated by decrease O2/pH/increase CO2 = decrease BP
role of peripheral baroreceptors
stimulated by high BP = lower BP
nervous system involvement in lowering BP
decrease sympathetic NS
increase parasympathetic NS
what is the developmental significance of the ligamentum arteriosum
remnants of shunt between PA and aorta
shunt closes at birth
how may fibrous pericardium contribute to reduction in ventricular filling
pericardium swells with fluid over time
will limit ventricular filling = lower stroke volume
this increases heart rate to try and increase cardiac output as pericardium is resistant to stretch
what phase of the cardiac cycle do coronary arteries fill
pressure is highest during systole so some CA fill but most in the myocardium so squeezed empty
during diastole pressure in myocardium decreases so CA fill
where is the SAN located
superior end of crista terminalis at the junction of SVC and RA
what is the thoracic duct
main lymphatic channel draining lymph from half of body back to bloodstream
what does the greater splanchnic nerves supply and where is pain felt
foregut but felt in epigastrum
what does the lesser splanchnic nerves supply and where is pain felt
midgut but felt round umbilicus
what does the least splanchnic nerves supply and where is pain felt
hindgut but felt suprapubic region
what structures drain blood into the azygous system
body walls
mediastina viscera
lateral/posterior chest wall
lateral/posterior abdo wall
difference between L and R laryngeal nerve
left passes through thorax
where do the sympathetic nerves attach to the nervous system
T1-T12
L1-L2
sympathetic nerves to head/neck disrupted leads to
Horner’s syndrome
what factors affect BP (5)
CO compliance volume of circulating blood lifestyle factors genetics
when is the myocardium perfused
in heart relaxation (diastole)
during cardiac cycle theres a greater flow of blood through which coronary arteries
left in most people
what are the consequences of a LAD occlusion
myocardial infarction in front/bottom of LV and front of septum
nausea, shortness of breath, pain in head/jaw/neck
induces cardiac arrest
what are the consequences of a RCA occlusion
RCA supplies SAN/AVN
chest pain, shortness of breath
leads to ischaemic myocardium and conduction abnormalities
are RBC precursors found in the blood
no, this is a sign of leukemia
what is myogenic autoregulation
when blood flow increase smooth muscle constricts until diameter is normalised/slightly reduced.
when blood flow decrease smooth muscle relaxes and dilates in response.
what is intrinsic autoregulation
when arterioles either vasoconstrict or vasodilate in response to changes in resistance seemingly automatically to maintain constant blood flow
what is hyperaemia
increase in blood flow
what is active hyperaemia
increase in blood flow when metabolic activity is increased
what is reactive hyperaemia
transient increase in organ blood flow that occurs following a brief period of ischaemia
what happens at the P wave
atrial depolarisation
0.08-0.11s
what happens at PR interval
time taken for atria to depolarise and electrical activation to reach AVN
0.12-0.2s
what happens at the QRS complex
ventricular depolarisation
0.06-0.1s
what happens at ST segment
interval between depolarisation and repolarisation
0.005-0.150s
what happens at the T wave
ventricular repolarisation
what happens at QT segments and how long does it take
ventricular depolarisation then repolarisation
0.2-0.4s
what is the conduction pathway
SAN
AVN
bundle of His
Purkinje fibres
how is the His-Purkinje system specialised (4)
rapid conduction
large fibres
high permeability at gap junctions
spreads from endocardium to pericardium
what does an ECG show
changes in voltage over time
p waves are positive in every lead apart from
aVR
t waves are positive in every lead apart from
aVR/sometimes V1/V2
what is anaemia
reduction in haemoglobin in the blood
what is the normal Hb levels
12.5-15.5g/dl
what is iron deficiency anaemia
iron needed for Hb production
lack of iron result in reduced production of small red cells
what is MCV
mean corpuscular volume
= average size of RBC
how does vitamin B12/folate deficiency lead to anaemia
B12/folate needed for DNA synthesis
deficiency = RBCs cannot be made in bone marrow = less are released = anaemia
what is haemolysis
normal/increased RBC production but decreased life span (<30 days)
how is a delay created at AVN
has less gap junctions
what happens at day 19 heart development
2 endocardial tubes form
what happens at day 22 heart development
embryo undergoes lateral folding
2 endocardial heart tubes fuse to form single tube
what develops from the bulbus cordis
proximal 1/3 = muscular RV
conus cordis = smooth outflow portion of LV/RV
what develops from the truncus cordis/arteriosus
proximal aorta and pulmonary trunk
what develops from the primary ventricle
left ventricle
what develops from the primary atrium
anterior RA
entire LA
L/R auricles
what develops from the sinus venosus
part of RA/VC/coronary sinus
where is the CVS embryologically derived from
mostly the mesoderm
some contribution from neural crest cells from ectoderm
what occurs in cardiac looping
- bulbus cordis and primary ventricle grow
- BC moves inferiorly, anteriorly and right
PV moves to left - PA, SV move superiorly and posteriorly
truncus arteriosum form
what are the stages of cardiac embryological development
- heart tube fuse
- cardiac looping
- cardiac septation = 4th - 5th week
what is vasculogenesis
angioblasts from mesoderm coalesce to form angioplasties cords throughout embryonic disc
= migrate to form the aorta
what is angiogenesis
driven by growth factors = adds to vasculogenesis through proliferation and sprouting
what does 3rd aortic arch develop into
L/R common/internal/external carotid arteries
what does 4th aortic arch develop into
Left = part of aortic arch Right = part of right subclavian artery
what does 6th aortic arch develop into
left = L pulmonary artery and ductus arteriosus right = R pulmonary artery
foetal circulation
- oxygenated from placenta via umbilical vein
- bypass liver via ductus venosus = combine with deoxy in IVC
- join with blood from SVC and enter RA
- RA shunted to LA
- blood to aorta via ductus arteriosus
- deoxy to placenta via umbilical arteries
what occurs after birth
- increased alveolar O2 = vasodilation of pulmonary vessels
2. increased LA pressure/decrease RA pressure = foramen ovale close
what happens to the foramen ovale after it closes
becomes the fossa ovalis
3 granulocytes
neutrophils
eosinophils
basophils
2 agranulocytes
lymphocytes
monocytes
the heart is mainly composed of
myocardium
what are the heart valves composed of
fibro-elastic connective tissue
what is the surface of the heart valves covered by
endocardium
includes a layer of endothelial cells
what is the surface of the heart covered by
mesothelial cells that form the visceral pericardium
what does the medial layer of blood vessels contain
smooth muscle
elastic
collagen
what does the adventitia layer of blood vessels contain
densely packed collagen and elastic fibres
how does cardiac muscle differ from skeletal muscle
structurally = branched, central mononuclear, no stem cells physiological = contract/relax without rest, secrete hormones
what hormone does cardiac muscle secrete and what does it do
ANP
when stretched excessively = increase water/K+/Na+ excretion and inhibit RAAS
what is the role of gap junctions
allow ion transfer between cardiac smooth muscle = electrochemical coupling
what colour do purkinje fibres stain with PAS
magenta
purjinke fibres histology characteristics
large vacuoles
pale H&E bc few myofibrils
stores glycogen
histology of valves
thick collagen occasional elastic tissue
both surfaces have endothelial cellss
fibrous chordae tendinae
what is the pericardium made up of
single layer of mesothelial cells on BM with thin loose elastic and fibrous tissue
what is the endocardium made up of
endothelial cells on BM with thin loose elastic and fibrous tissue
what are the colours of an elastic artery with mallorys stain
elastic = red collagen/muscle = blue
capillary diameter is same as
RBC
what are the 4 functions of endothelial cells
- AT across membrane
- influence muscle tone
- coagulation
- produce cell adhesion molecules to influence lymphocyte/neutrophil migration
what type of muscle do large veins have in their medial layer
smooth muscle
what colour do lymph vessels stain
blood plasma and valves stain pink
what are reticulocytes
immature RBC with some visible ribosomes = dark staining granules
why can muscular arteries reduce their diameter
have smooth muscle in media
elastic tissue van gieson with iron haemotoxylin counter stain
elastic = black
smooth muscle = mushroom
collagen = pink
name 2 hormonal vasodilators
atrial natriuretic peptide
adrenaline