cardio Flashcards
Explain which and how intermediate control mechanism of arterial blood pressure can
increase blood pressure back to normal if it was too low!
Renin- angiotensin system:
The liver will produce angiotensinogen and release it into
blood. When blood pressure decreases, the kidneys release renin which converts
angiotensinogen in the blood into angiotensin I. Blood will be delivered to the
pulmonary circulation where endothelial cells contain high concentrations of
angiotensin converting enzymes that convert angiotensin I into angiotensin II.
Angiotensin II reaches all blood vessels in the body and causes vasoconstriction.
Angiotensin II is one of the strongest vasoconstrictors in our body, which in
nanogram concentration can increase arterial blood pressure by 20-40 mmHg.
- Fluid reabsorption: With low blood pressure there will be a reabsorption of interstitial
fluid into the capillaries and a smaller filtration out. When pressure in the interstitium
is higher than the pressure inside the capillary → reabsorption takes place. This will
restore the blood pressure.
- Stress relaxation: (Stress refers to stress of the smooth muscle cells in the blood
vessel wall. Stress of the smooth muscle cell is caused by the stretch of the cell).
Sudden stress of smooth muscle cells causes deformation Ca2+ channels to open
which leads to contraction of smooth muscle cells. If the stress goes on for several
minutes or hours, the smooth muscle cell will adapt to the stretch. This will lead to
deformation Ca2+ channels closing and the calcium concentration in the cell will
decrease, leading to relaxation of the smooth muscle cells. Relaxation of the smooth
muscle cells causes less tension of the blood vessel wall which might decrease the
blood pressure. Stress relaxation due to continuous stretching of the blood vessel wall
causes relaxation of smooth muscle cells in its wall.
Meaning:
If the blood vessel wall is subjected to high pressure over a long time,
the muscle cells will relax and accept the high blood pressure instead of working
against it.
Characterize sympathetic nervous system effects in the cardiovascular (heart and
different blood vessels) and urogenital system!
The sympathetic nervous system will cause an increase in heart rate, force of
contraction, excitability, velocity of conduction and increased speed of relaxation
- For the urogenital system in males there will be an ejaculation and for women that are
pregnant there will be a contraction and for non pregnant women there will be a
relaxation in the uterus.
Explain the role of different types of calcium channels in the cardiac muscle (name a
type, location and explain its function)!
In cardiac tissues, the two types of calcium channels are the L type and the T type.
L-type channels are found in all cardiac cells and T-type are expressed in Purkinje
cells, pacemaker and atrial cells. Both these types of channels contribute to
atrioventricular conduction as well as pacemaker activity.
Explain pressure of volume changes in the left atrium and left ventricle during
the filling phase!
During the filling phase in the left ventricle the pressure is much lower than
the pressure in the aorta which means that the semilunar valves will still be
closed. The filling phase is divided into two phases: the passive and active
filling phase. The blood will flow from the veins through the atria into the
ventricles, the ventricle will receive about 80% of the blood. The active
filling phase also known as the atrial systole will push the remaining 20% of
the blood into the ventricle for the next atrial systole. Pressure in the atria and
ventricle will rise.
- During the filling phase in the left atrium the pressure in the ventricle is lower
than the pressure in the atrium. This means that the atrioventricular valves are
open and the blood will enter the ventricles. For the passive phase the blood
will flow passively from the veins through the atrium into the ventricles,
filling the ventricles with about 80%. In the active filling phase (atrial
systole) the next atrial systole will begin and the atrial muscle contraction
will push the remaining 20% of the blood into the ventricle to fill its maximal
volume.
. Name and give a size of volume of the left ventricle at the beginning and at the
end of filling phase
At the beginning of the filling phase the volume is called end systolic volume
(residual volume + reserve volume) (30-60 depending on person &
contraction strength), after the filling the volume is called end diastolic
volume (110-150ml) (residual volume + stroke volume + reserve volume)
Indicate the blood volume delivered to the skeletal muscle. Indicate its changes during
exercise
- The skeletal muscles receive 21% from the cardiac output. This is 3-5 ml/min/100g.
During exercise the percentage they receive may reach 85% of the CO and 50-80
ml/min/100g
Explain the cause of the QRS complex (each wave if possible) and QT interval in
the electrocardiogram and provide normal values!
- QRS complex starts at the beginning of Q to the end of S. It shows the
depolarization of the ventricles, normal values are 0,06-0,1s. R is always
present and positive, it represents the depolarization of the main mass of the
ventricle. Q and S waves are not always present in an ECG but they are
normally always negative. The Q wave corresponds to depolarization of the
interventricular septum. The S wave signifies the final depolarization of the
ventricles, at the base of the heart - QT interval is shown from the beginning of the Q wave to the end of the T
wave. It represents depolarization and repolarization of the ventricles.
Normal values are 0,30-0,45s.
Measure and evaluate the duration of QRS complex and QT interval in this
electrocardiogram!
- QRS ––> 3*0,02= 0,06s which is normal value
- QT interval ––> 45= 20
200,02=0,4s which is normal value
Indicate the blood volume delivered to the lungs. Indicate its changes during exercise.
- The lung circulation is divided into the bronchial circulation and the pulmonary
circulation. The pulmonary circulation receives 100% of the cardiac output (from the
right atrium, venous blood) to oxygenate it for it to be later sent to the rest of the
body. The bronchial circulation receives 1 to 2 % of the cardiac output.
Explain differences in reflex arch between somatic and autonomic nervous system!
The afferent part is the same in somatic and autonomic systems but the efferent part of the reflex arch
has multiple differences.
- Higher centers: SNS has its highest center in the cerebral cortex and ANS has its highest
center in the hypothalamus.
- Lower centers: SNS lowest center are all segments of the spinal cord while the ANS has the
lowest centers in the thoracic, lumbar and sacral part of the spinal cord.
- Conscious/ Subconscious: The SNS is conscious because the cerebral cortex controls the
consciousness. The ANS is subconscious.
- Reflex center: meaning the location of the neuron cell body, the SNS has it located in the
anterior horn and in the ANS its located in the lateral horn of the spinal cord.
- Efferent pathway: in the somatic reflex arch the efferent pathway is made up from one neuron
while in the autonomic its made from two neurons preganglionic and postganglionic neurons.
The preganglionic neuron leaves the spinal cord and synapses with the postganglionic one
that is located outside of the spinal cord.
- Nerve fiber types: The somatic will have well myelinated A alpha or A gamma nerve fibers,
they will have a fast speed of impulse conduction. In the autonomic preganglionic neuron
there are B group fibers and the postganglionic belongs to the C group, the B group fiber is
less myelinated while the C group fibers are unmyelinated.
- Conductor (effector): In the somatic reflex arch it is skeletal muscle while the autonomic has
three possible effectors; cardiac muscle cells, smooth muscle cells and secretory cells
- Neurotransmitter & the receptors in the synapse with the effector: Somatic reflex arch has a
Acetylcholine neurotransmitter that binds to a nicotinic receptor. While the autonomic
nervous system has several options. The neurotransmitter can be acetylcholine but it will bind
to the muscarinic receptor. The neurotransmitter can also be epinephrine or norepinephrine
and it will bind to either alpha or beta adrenergic receptors.
- Reflex time: The autonomic reflex arch has a longer reflex time, it’s because of three reasons.
The first reason is because it has at least one more synapse compared to the somatic reflex
arch. The second reason is because it has ANS has slow conducting fibers while SNS has fast.
- Co-transmission: Happens only in the ANS. Co-transmission means that together with the
already existing neurotransmitters additional neurotransmitters can be packed together in
vesicles. The neurotransmitter that can be packed together with AcH is VIP. NE is usually
released together with ATP and NPY
Explain the local regulation mechanisms that can lead to dilation of cerebral
blood vessels
Metabolic regulation: results in vasodilation when the partial pressure of carbon
dioxide increases and partial pressure of oxygen decreases. The blood vessels will
dilate to compensate for the lack of oxygen.
- Humoral regulation: vasodilation happens when the release of nitric oxide is done.
Nitric oxide will activate cAMP which activates kinase which leads to less calcium
which means it will affect the diameter.
- Myogenic regulation: there will not be a stretch which means there will be a
relaxation of the smooth muscle cells.
. Explain venous blood flow differences from arterial
- Low blood pressure – veins are less elastic than arteries, and because of that
they have a very large capacity to hold blood. 15 – 0 mmHg. - Low pressure difference – only 15 mmHg, while in arteries the difference is
approximately 65 mmHg. The low pressure difference leads to slow blood
flow. - Bigger cross-sectional area – decreases the blood flow.
- Slower linear velocity – the velocity is constant. In arteries the velocity is
high, and decreases when the blood reaches the capillaries. 0.15 – 0.2 m/s - Blood flow in one direction with the help of valves- They work passively. If
the pressure before the valve is greater than the pressure after the valve, they
will open. If the pressure before the valve is lower than the pressure after
valve, they will close. - Greater compliance – Stretch well, can hold more blood and work as a blood
depot
Explain mechanisms that facilitate venous blood return (muscle pump,
respiratory pump, heart pump)
- Muscle pump:
- When the skeletal muscles contract, the upper valve will open and
the lower valve will close leading to increased blood pressure
because blood is pushed up. When the skeletal muscle relaxes, the
upper valve will close because of greater pressure from above, this
also prevents backflow. The lower valve opens and the vein is filled
again. This describes why there is greater venous return when
standing up. - Respiratory pump:
- During inspiration, the diaphragm moves down → increased
pressure in the abdominal cavity → compresses the veins in this area.
At the same time, the pressure in the thoracic cavity decreases. This
process leads to decreased pressure in the veins of the thoracic cavity,
but increased pressure in the abdominal veins, so the abdominal veins
push blood into the thoracic veins. - During expiration, the pressure in the thoracic cavity increases, so
thoracic veins are compressed, and more blood is pushed in the
direction of the heart. - Heart pump:
- Works during systole, especially ejection phase.
- During the ejection phase, the AV plane moves down towards the
ventricles, which stretches the atria and decreases pressure in them.
Because of the decreased pressure, the atria is able to “suck” blood
from the great veins.
a. Indicate the blood volume that is delivered to coronary circulatory
about 200 ml/min and 4% cardiac output. During exercise it rises up to
250mL/min/100g.
. Explain mechanisms that can lead to dilation of coronary arterioles
Central: neuronal, hormonal
- Central neural regulation activates sympathetic fibers, from T1 to L3;
Acetylcholine binds to M3 cholinoreceptors. - Central hormonal regulation releases epinephrine binding to B2, ANP & BNP
are also released as vasodilators but they are weak.
Peripheral: metabolic, humoral, myogenic - Peripheral metabolic regulation has increased partial pressure of carbon
dioxide and K+ and adenosine while having decreased oxygen levels and pH
levels. - Peripheral humoral regulation releases PGI2, histamine, NO, kinins, EDHF to
cause a vasodilation - Peripheral myogenic regulation will have no stretch in the smooth muscles
causing a relaxation
Measure the duration of P wave, PQ segment and PQ interval in the
electrocardiogram. Speed of recording 50 mm/s, amplification 10 mm/mV.
P wave duration: 4 x 0,02= 0,08s
- PQ segment duration: 2,5 x 0,02= 0,05s
- PQ interval duration: 7 x 0,02= 0,14s
Explain the cause of P wave, PQ segment and PQ interval in the
electrocardiogram and give their normal values!
- P wave: shows the depolarization of the atria. Normal values are 0,06-0.1s
- PQ segment: shows the impulses that are spread through the atrioventricular
node. Normal values are 0,04-0,1 s - PQ interval: shows the impulse spread through the atria to the ventricle.
Normal value are 0,12-0,20 s - The patient showed all normal values
- Name phases of the action potential of the working myocardium cell. Explain changes of
ion permeability in the cell membrane during the different phases of this action
potential
The working myocardium has no automaticity, they are dependent on pacemaker cells
and external electrical stimuli. They have resting membrane potential at -90 mV.
- Fast depolarization (phase 0): impulse comes that opens the voltage gated sodium
channels. When the sodium ions rush into the cell it causes a fast depolarization.
- Initial fast repolarization (phase 1): The voltage gated sodium channels close and the
voltage gated potassium channels open causing an outflux of potassium. At the same
time a small amount of chloride ions goes in.
- Slow repolarization/plateau (phase 2): L- calcium channels open leading to a calcium
influx and outflux of potassium. The exchange is equal meaning that the membrane
potential does not change much causing the “plateau look”. This goes on for about
100 ms.
- End fast repolarization (phase 3): The L-calcium channels close. But additional
potassium channels open which leads to a potassium outflux that decreases the action
potential rapidly back to the initial resting membrane (-90mV).
. Explain the effect of epinephrine on the heart including the effect on a cellular level (also
mention the site of production of epinephrine and the receptors it binds to)
- The effect of epinephrine in the heart is started from the sympathetic nervous system
being triggered (fight or flight). Epinephrine will bind to β1-receptor and stimulate Gprotein which will activate adenosine cyclase (AC). AC will convert ATP to cAMP.
cAMP increases permeability of sodium and calcium-channels in the cardiac muscle
cell membrane. With the sodium and calcium influx in the cell there will be a rapid
depolarization which leads to the increase of heart rate of the person. Since more
calcium ions come into the cell, it binds to the troponin to activate contractile
filaments which increase the force of contraction. The increased permeability to
sodium and calcium ions can cause and increase excitability of the cardiac muscle
cells. It can also increase the speed of conduction and increase relaxation rate (all
positive effects on the heart)
20 years old female person has blood pressure 120/95 mmHg and heart rate 84 x/min
a) Give normal range of arterial blood pressures and indicate if blood pressure for
this person is normal!
Normal blood pressure should be lower than 120/80, for systolic it should be
90-120 mmHg and for diastolic it should be 60-80 mmHg. The systolic blood
pressure is normal but the diastolic is a bit higher than normal. Normal heart
rate: 60-100 x/min
State at which moment the systolic/diastolic blood pressure is read:
in the auscultatory method: the first sound that is hearable after we deflate
the cuff is the systolic and after that we will hear a turbulent blood flow, once
the blood flow is not hearable anymore the diastolic pressure is determined.
- in the palpatory method: the diastolic pressure cannot be measured since
there is no stethoscope, but when placing the fingers on the artery it will
allow us to register systolic pressure, this method can be used when the
surroundings are loud.
Calculate the mean arterial pressure for this person! Provide the calculation
formula!
- ⅓(PS) + ⅔ (PD) ––>⅓ (120) + ⅔ (95) ––> 40 + 63= approximately
103mmHg
Calculate the pulse pressure of this person! Provide the calculation formula!
Pulse pressure: Ps-Pd= 120-95= 25 mmHg
Evaluate the elastic and peripheral resistance for the circulatory system from the
given data; indicate parameters on which your conclusions are based on!
- The peripheral resistance is high for this individual, because the diastolic
pressure is above normal ranges (60-80 mmHg). The high peripheral
resistance = decreased overall compliance = high diastolic BP. The elastic
resistance is normal or (low), meaning that the aorta is elastic and can expand
during ejection, which keeps systolic blood pressure within normal values
(90-120 mmHg).
Explain the innervation and function (including effects) of the adrenal medulla.
- The adrenal medulla is innervated by the sympathetic nervous system. The adrenal
medulla produces mostly epinephrine (80%) and it causes different functions. such as;
increased metabolic intensity like fat breakdown in adipose tissues, increasing
glucose levels in blood. Increase heart activity by having positive effects. Decrease
motility and secretion in gastrointestinal tract. Dilate bronchi, dilate pupils and relax
ciliary muscle to widen and adapt to the far vision. Increase sweating secretion.
Stimulate platelet aggregation to speed up clot formation.
Characterize the sympathetic nervous system effects in the respiratory system
and eyes.
Respiratory: The diameter: There will be bronchodilation. The bronchial glands:
Less secretion
Eyes: M. dilatator pupillae: The pupils will dilate. M. ciliaris: The ciliary muscle will
relax
Indicate centers of the sympathetic nervous system, indicate neurotransmitters
and receptors in synapse with the effector.
- The highest center of the SNS is the hypothalamus and the lower centers are
in the T1-L3 segments. The neurotransmitter that is released in the
preganglion is Acetylcholine and it will bind to the nicotinic receptors. In the
postganglion the neurotransmitters that are released and synapsing with the
effector are Norepinephrine or Epinephrine and they will bind to either alpha
or beta receptors. In sweat glands, some blood vessels of skeletal muscles,
coronary circulation and in the brain there is Acetylcholine and it will bind to
muscarinic receptors.
What effects in the respiratory system will be caused by propranolol? Explain it!
- Propranolol blocks beta receptors and b2 receptors exist in the respiratory
tract, the stimulation will lead to bronchoconstriction, leading to breathing
problems to people with already pre- existing breathing diseases such as
asthma.
Explain when during the cardiac cycle extrasystole can be triggered:
- When a stimulus is given after the ARP but before the end of the diastole, and
the stimulus is strong enough to cause a contraction, an extra-systole
(=extracontraction) can be observed
Explain why it cannot be triggered in the other part of the cardiac cycle
- It cannot be triggered before the ARP because excitability is 0%, and after the
diastole then a stimulus would just cause normal systole, and heart wouldn’t
skip a beat.
Explain the cause of compensatory pause after extrasystole
- Because a new stimulus is needed to cause a new contraction, but the natural
stimulus (of the pacemaker) falls into the ARP of the extrasystole → it
doesn’t cause a contraction. It compensates for the arrhythmia caused by the
extrasystole & ensures that the heart beats in its normal rhythm again.
Indicate the volume of blood that adult persons brain receives during rest and
physical exercise:
- 14% of cardiac output and 700ml/min for the resting cerebral blood flow.
During physical activity the brain receives more blood , up to 750 ml/min
. Explain the peripheral (local) regulation mechanisms that can lead to dilation of
cerebral blood vessels
- Metabolic regulation: results in vasodilation when the partial pressure of
carbon dioxide increases and partial pressure of oxygen decreases. The blood
vessels will dilate to compensate for the lack of oxygen. - Humoral regulation: vasodilation happens when the release of nitric oxide is
done. nitric oxide will activate cAMP which activates kinase which leads to
less calcium which means it will affect the diameter. - Myogenic regulation: there will not be a stretch which means there will be a
relaxation of the smooth muscle cells.
Name elements of the electrocardiogram that indicate electrical events in
ventricles, explain their cause and give normal values.
- QRS complex shows the depolarization the ventricles: 0,06-0,1s
- T wave shows the repolarization of the ventricles: 0,2-0,4 mV
- QT interval shows the depolarization and repolarization of the ventricles:
0,3-0,45s
Explain changes of blood pressure in the left ventricle and left atrium during the
isovolumetric relaxation phase; indicate the state of valves during it!
- Blood pressure in left ventricle will drop rapidly in isovolumetric relaxation
since the surface expands and it increases in left atrium since the ventricle
previously pulled it with when it contracted. Now that it can go back, it
decreases the surface and heightens the pressure. During isovolumetric
relaxation, both AV and SL valves are closed.
How do we call the blood volume in ventricle at the beginning of
isovolumetric relaxation phase? How much is it?
End-systolic volume. Reserve volume 20-40 ml + Residual volume 10-20 ml
Which heart sound we can record at the beginning of the isovolumetric
relaxation? What is the cause of it?
Second heart sound. This sound is caused by the SL valves closing.
Characterize the parasympathetic nervous system effects in the cardiovascular
( heart and different blood vessels) and urogenital system.
- The parasympathetic nervous system will cause an decrease in heart rate,
force of contraction, excitability, velocity of conduction and decreased speed
of relaxation. - For the urogenital system the wall of the bladder will contract while the
sphincters will relax.
