FUCK!!! Flashcards
the AV valves between atria and ventricles
tricuspid and mitral valves
chronotropy
rate of depolarization; heart rate
ionotropy
aka contractility; Ca2+ binds troponin
preload
ventricular filling ~ end diastolic volume
blood flows from
high to low pressure
how much of ventricular filling is passive
80%
s3 and s4 heart sounds
s3 can be healthy or pathologic
s4 is pathologic; atria force blood into non compliant ventricle
which ventricle has the higher pressure
Left Ventricle
Aorta is 120/80mmHg so its
the blood pressure value
more force; atria or ventricles
ventricles
ACXVY for at the atria
A wave: atrial contraction (atrial systole)
C wave: tricuspid buldge
X-descent: atrial relax (atrial diastole)
V wave: passive filling (ventricular systol)
y-descent: atria empty into ventricles with open AV valves
dicrotic notch
division between 2 waves in aortic valves; when valve closes (elastic recoil)
Stroke volume
volume ejected with each heart beat
SV=
SV= EDV-ESV
cardiac output
volume ejected each systole x heart rate
–> give o2 and nutrients to tissues
–> equal in left and right ventricles
CO=
CO = SV x HR
ejection fraction
proportion of EDV ejected with each heart beat
–>estimated heart function in heart failure
EF=
EF= SV/ EDV
EF= (EDV-ESV)/ EDV
preload of 1 ventricle depends on ____ of other ventricle
cardiac ouput
treppe effect
accumulate Ca2+ in SR as HR increases (not enough time to remove calcium)
skeletal myocyte excitation- contraction coupling
Ach (nicotinic receptor) –> depolarize –> Na+ VGC open –> Ca2+ VGC open –> t tubules get AP deeper –> Ca2+ binds troponin and open the myosin binding site on actin by moving tropomyosin out of the way –> cross bridge formation
where does most of the calcium come from in skeletal muscle contraction
little bit from Ca2+ VGC
but the main action of Ca2+ VGC is to open ryanodine receptor in SR and the SR is where most of the Ca2+ is from
cardiac myocytes differences from skeletal myocytes
-no tetany bc long refractory period
-synctium; intercalated disks (gap junctions and desmosomes) = coordinated heart contraction
-t tubules less important; rely more on L-type Ca2+ channels
-1 nucleus, lots of mitochondria; ATP, oxidative metabolism with fats
automatic cells 4 phases
phase 4: unstable, funny current (Na+ and K+)
phase 0: depolarize by L-type Ca2+ channels (NOT Na+ VGC)
-no phase 1 or phase 2 plateau
-phase 3: repolarize; K+ efflux
where is there a delay in heart conduction
AV node; give atria time to eject blood to ventricles and time for ventricles to fill
bundle of His (AV bundle) purpose
carry AP along septum to ventricle
purkinje fibers carry AP to…
apex then base = ventricular contraction
fibrous skeleton so
atria and ventricles can only communicate through AV node
Bachman’s bundle
right and left atrium contract simultaneously
4 major types of APs in the heart
- myocyte APs (ventricular and atrial)
- purkinje cell APs (almost same as ventricular but unstable 4 like automatic cell)
- automatic cell APs
automatic cells
-SA and AV node
-depolarize without external stimuli
what cell takes over in complete heart block
purkinje cells give AP because cant go from atria to ventricles with AV node and SA
SA node is
pacemaker; HR = 60-100bpm
4 typical phases of myocyte APs
phase 4- resting membrane potential, leaky K+, Nernst = -84mv
phase 0- rapid depolarization, Na+ VGC open; influx
phase 1- initial repolarization, close Na+ VGC, K+ VGC open= efflux
phase 2- plateau- open L-type Ca2+, influx (Ca2+ and K+ balance out)
phase 3- slow repolarization; close Ca2+, open slow K+ VGCs
calcium spark
1 Ca2+ VGC opens and elicits small Ca2+ release from neighbouring ryanodine receptor on SR –> summation = increase in Ca2+ in cytosol (some contribution from ECF)
3 things remove Ca2+ from cytosol
-SERCA
-Na+ Ca2+ exchanger; 3 Na in, 1 Ca out
-sarcolemma calcium ATPase; Ca out
what is SERCA regulated by
phospholambdin phosphorylation
beta 1 receptors (SNS)
beta 1 –> cAMP –> phospholambdan –> phosphorylate troponin –> L-type Ca2+ VGC –> Ca2+ influx –> enhance contractility and quicker Ca2+ reuptake into SR
ECG measures? what is a little box?
electrical activity
-little box is 0.1mV high and 0.04 seconds wide
P wave
atrial depolarization via SA node
PR interval
impulse from SA node through atria and AV node to ventricles (AV node delay for ventricular filling)
AP from SA –> AV node
QRS complex
ventricular depolarization (via bundle of His and Purkinje)
ST segment
ventricles fully depolarized, before they depolarize
T wave
ventricular repolarization
QRS interval
AP from end of AV node to throughout ventricles
QT interval
ventricle depolarize and repolarize
3 layers of blood vessels
tunica intima
tunica media
tunica externa/adventitia
tunica intimia is made of
simple squamous endothelium
tunica media is made of
muscle cells
which layer is thickest in arteries
tunica media
which layer is thickest in veins
tunica externa/adventitia
tunica externa/adventitia components
vasa vosaorum (blood vessels), fibroelastic CT
4 types of arteries
elastic arteries/conducting
muscular arteries/distributing
arterioles
metaarterioles
elastic arterioles/ conducting
i.e. aorta, pulmonary trunk
elastic fibers for high pressure near heart, major pressure reservoirs
muscular arteries/ distributing
i.e. brachial and femoral arteries
smooth muscle, most abundant in body
most common artery in body
muscular arteries/ distributing
arterioles
constrict and dilate, control systemic BP
metaarterioles
regulate flow into capillaries via pre capillary sphincters
3 types of capillaries
continuous capillaries
fenestrate capillaries
sinusoidal capillaires
which are the majority of capillary in the body
continuous capillaries
what is least permeable and most permeable capillary
least- continuous capillary
most- sinusoidal capillary
continuous capillaries
least permeable, majority, intercellular junctions for water soluble substances to pass
exception: BBB, BtestesB –> tight junctions (Claudius and occluding)
caveolae (caves): endocytosis of macromolecules
intracellular cleft; for small (albumin cant go through)
coalesces and make vesicular channels –> pinocytosis and endocytose ECF –> increase in inflammation to transport antibodies and nutrients
3 types of veins
large
medium
small (venules)
large veins
vena cava, portal vein, pulmonary veins
thick tunica advanetitia with dense CT, collagen, elastic fibers, vasa vasorum
medium veins
femoral, renal and brachial veins
valves to prevent back flow to limbs
small veins (venules)
post capillary and collecting venules
collect blood from capillaries
valves formed via
reflection of tunica intima
lumen bigger in vein or artery
vein
2/3 blood in
systemic vein
veins can somewhat constrict via
catecholamines
poiselles law vs Reynolds #
poiselles; laminar flow
Reynolds; turbulent flow (i.e. atherosclerosis, hypotension)
–> likely if increased blood velocity, decreased or irregular diameter and decreased viscosity (faster)
pressure and velocity in arteries, capillaries and veins
arteries- high pressure, fast velocity
capillaries- low pressure, slow velocity
veins- low pressure, moderate velocity
basement membrane of capillaries
type IV collagen
series circulation vs parallel circulation
series- higher resistance
parallel- majority, reduce resistance even though small radius i.e. capillaries
lower resistance in parallel or series circulation
parallel
compliance
amount of pressure need to change volume
high compliance
small amount of pressure= large change in volume
what are more complaint; veins or arteries
veins; blood resevoir
arteries have low compliance to maintain high BP
mean arterial pressure MAP
MAP= DP + 1/3 (SP-DP)
1/3 of cardiac cycle in systole
edema
too much movement across capillary walls
albumin keeps H2O in capillary
glycosaminoglycans absorb H2O and reduce edema
what reduces edema
albumin and glycosaminoglycans
2 ways capillary blood flow is regulated
- autoregulation
2.myogenic regulation
autoregulation of capillaries
capillary bed regulates flow via local tissue factors
h2o, o2, co2, [lactate, K+, adenosine= exercise] all vasodilate
myogenic regulation of capillaries
constant flow despite changes in MAP because if pressure drops then dilate and if pressure increases then constrict
Increased Blood Pressure (Stretch):
When blood pressure increases, it causes the walls of arterioles (the small arteries leading to capillaries) to stretch.
The smooth muscle cells in the walls of these arterioles respond to this stretch by contracting (a phenomenon known as the myogenic response). This constriction reduces the diameter of the arteriole, thereby decreasing the flow of blood into the capillaries.
This is a protective mechanism to prevent overdistention of the capillaries and potential damage to delicate capillary walls.
Decreased Blood Pressure (Reduced Stretch):
When blood pressure decreases, the walls of the arterioles are less stretched. In response, the smooth muscle cells in the arteriole walls relax, causing the arterioles to dilate.
This dilation helps maintain blood flow through the capillary network by preventing the pressure in the capillaries from becoming too low, ensuring adequate perfusion to tissues.
NO effect and pathway
vasodilate via shear stress
NO –> guanylyl cyclase –> cGMP –> PKG –> dephosphorylate myosin and relax
vasodialtors of capillaries
histamine
bradykinin
prostaglandin E2 and I2
NE, E via beta 2 receptors
vasoconstriction of capillaries
NE, E alpha 1 receptors
serotonin
ADH
AT II
thromboxane A2 and prostaglandin F
NE and E 2 receptors
beta 2= vasodilate
alpha 1= vasoconstrict
cerebral blood flow is regulated by
ph and adenosine