Heart/Cardiac cycle

Question 1

tissue perfusion

Answer 1

parallel circuity
-sympathetic and parasympathetic- changes shunting of blood in these areas
-100% blood leaves the aorta
-15% to brain
-5% coronaries- supply myocardial tissue (small goes to pericardium)
-25% to kidney- regulates blood pressure, filters blood, electrolyte management (pumps), removal of waste and medications*
-25% GI- absorption, peristalsis, liver
-25% skeletal- movement
-5% skin- thermoregulation, absorption, sensory
-100% blood back to lungs

Question 2

area and volume of blood

Answer 2

-significant amount of surface area is in the capillary compared to everything else
-the majority of the blood is in the veins- storage
-blood moves from high to low pressure -> veins are low pressure -> pools in veins
-higher volume higher pressure
-arteries- high pressure low blood volume
-veins- low pressure highest blood volume

Question 3

laminar flow

Answer 3

-blood flowing through the middle- maximal velocity
-silent
-velocity of flow at the vessel wall is 0
-parabolic

-turbulent flow- between arterial and venous (chaotic flow) - brewy turbulent flow you auscultate
-more pressure required for turbulent flow
-korotkoff sounds- BP via turbulent flow
-stenosis of blood vessels and cardiac valve disease -> turbulent flow -> murmurs

Question 4

diastolic heart failure

Answer 4

-not moving volume bc nothing is going in
-systolic heart failure- heart stretches and has less contraction

Question 5

pulmonary artery pressure

Answer 5

-15 MAP
-right ventricle systole- 25
-right ventricular diastole- 8

Question 6

arterioles

Answer 6

-pressure is pretty much constant at this point and further
-no more systole and diastole pressure changes
-highest resistance -> causes altered blood flow to organs
-extensive smooth muscle -> tonically active (always contracted)
-innervated by alpha 1 adrenergic receptors -> vasoconstriction (skin and splanchnic)
-innervated by beta 2 adrenergic receptors -> dilation (skeletal)
-resistance can be changed by sympathetic/catecholamine activity

Question 7

self depolarization

Answer 7

-involuntary

Question 8

functions of cardiovascular system

Answer 8

-regulation of BP
-delivers regulatory hormones from endocrine glands to target tissue
-regulation of body temp
-homeostatic adjustments to altered physiologic states -> hemorrhage, exercise, changes in posture

Question 9

systemic and pulmonary circulation

Answer 9

-systemic- left heart, arteries, veins, capillaries -> perfuses everything but lungs
-pulmonary- right heart, arteries, veins, capillaries

Question 10

cardiac output

Answer 10

-rate of blood pumped from either ventricle
-left ventricle CO = right ventricle CO in steady state

Question 11

venous return

Answer 11

-rate of blood returned to atria from veins

Question 12

hemodynamics

Answer 12

-principle’s that govern blood flow
-flow, pressure, resistance, capacitance

Question 13

arteries

Answer 13

-thick walled -> can handle high pressure
-extensive elastic tissue, smooth muscle, and connective tissue

Question 14

capillaries

Answer 14

-thin walled, but LARGE SURFACE -AREA to do gas exchange
-single layer endothelial surrounded by basal lamina
-Lipid soluble substances cross the capillary wall by dissolving and diffusion
-Water soluble (ions) substances cross the capillary wall either through water filled clefts between the endothelial cells or through large pores (fenestrated)
-Not all capillaries have blood at all times-> selective perfusion depending on the metabolic needs of the tissues
-regulated by constriction and dilation of arterioles via sympathetic innervation

Question 15

venules and veins

Answer 15

-much less elastic tissue than arteries-> large capacitance (capacity to hold blood)
-high capacitance (compliance)
-largest percentage of blood
-AMOUNT OF BLOOD IN THE VEINS= UNSTRESSED VOLUME BC UNDER LOW PRESSURE
-alpha 1 adrenergic receptors-> CONSTRICTION of the veins -> reduces capacitance -> reduces the unstressed volume
-Velocity of blood flow and area have an INVERSE relationship -> bigger diameter of vein -> slower blood velocity

Question 16

blood flow

Answer 16

-2 factors- pressure different between 2 ends of vessel and resistance
-pressure difference- driving force
-resistant- impediment to flow
-greater pressure difference -> greater blood flow
-from high to low pressure
-higher resistance lower blood flow
-total peripheral resistance- resistance of entire systemic system

Question 17

poiseuille equation

Answer 17

-the relationship between resistance, blood vessel diameter, and blood viscosity
-increase in resistance as viscosity (η) increases
-Resistance increases as length (l) of the blood vessel increases
-**Resistance to flow is INVERSELY PROPORTIONAL to the fourth power of the radius (r^4 ) of the blood vessel
-if radius of vessel decreases by 1/2 resistance does not simply increase twofold—it increases by 16-fold (2 ^4 )

Question 18

sequential blood flow

Answer 18

-total flow is constant at each level in series
-pressure decreases as blood flows through each sequential component
-greatest decrease at arterioles bc they contribute largest resistance
-R total = R1 + R2 + R3 ….

Question 19

parallel blood flow

Answer 19

-total resistance is less than any individual resistances
-flow through each organ is a fraction of total blood flow
-no loss of pressure in major arteries
-MAP in each major artery is the same as MAP of aorta
-1/Rtotal= 1/R1 + 1/R2 + 1/R3…

Question 20

anemia

Answer 20

-decreased Hct
-reynolds number- predictor of turbulent flow
-reynold number is high in anemia bc of low blood viscosity and high CO -> increase in velocity of flow

Question 21

thrombi

Answer 21

-narrow vessels
-increase velocity at site of thrombus
-increases reynold number
-turbulence

Question 22

shear

Answer 22

-occurs if layers of blood travel at different velocities
-layers travel at the same velocity-> no shear
-Shear is highest at blood vessel WALL- bc there’s a big difference between a moving RBC and a stationary one
-At walls= no movement, next to walls= blood movement: therefore the
DIFFERENCE between blood at the walls and next to the wall is highest
-In the middle, everything is moving at the same speed -> no difference in velocity= no shear
-shear breaks up clusters of RBCs next to each other= decreases blood viscosity (no more clumps)
-Therefore, at the wall which has the HIGHEST shear, RBC aggregation and viscosity are LOWEST

Question 23

capacitance (compliance)

Answer 23

-volume of blood a vessel can hold at given pressure
-volume of blood in vessel changes for a given change in pressure
-veins high
-arteries low
-if vein capacitance decreases blood redistributes from unstressed to stressed volume

Question 24

blood pressure

Answer 24

-not the same throughout system
-bp differences is driving force
-pulmonary wedge pressure- measures left arterial pressure-> catheter in pulmonary artery into a branch -> catheter wedges and block blood flow from that branch -> once flow stops -> catheter senses pressure in left atrium
-diastolic- lowest arterial pressure during ventricular relaxation
-systolic- highest pressure after ventricular contraction

Question 25

why does pressure decrease as you move farther from heart

Answer 25

energy is consumed in overcoming frictional resistances

Question 26

stroke volume

Answer 26

-volume of blood ejected from left ventricle on single beat
-pulse pressure= systolic - diastolic = SV

Question 27

mean arterial pressure

Answer 27

-average pressure in complete cardiac cycle
-NEED TO KNOW
-why is MAP important? -> at the level of arterioles contraction pressure doesnt influence -> dependent on MAP
-we are in diastole more than we are in systole -> diastole x2
-MAP = diastolic + 1/3 pulse pressure
-MAP = (diastolic + diastolic + systolic) / 3

Question 28

arteriosclerosis

Answer 28

-plaque deposits in arterial wall
-decrease diameter
-stiff, less compliant
-SV causes much greater change in arterial pressure
-increases systolic, pulse, and mean pressure

Question 29

aortic stenosis

Answer 29

-aortic valve stenosis (narrow)
-opening is reduced -> less blood ejected
-decreases SV, systolic pressure, pulse pressure, mean pressure
-less blood enters aorta

Question 30

aortic regurgitation

Answer 30

-incompetent valve
-congenital
-pressure is very low
-pulmonary pressure is much lower than systemic
-pattern of pulmonary is analogous to systemic
-By the time the blood reaches the veins, pressure is already so low and will continue to drop even more in the vena cava and the right atrium

Question 31

QRS complex

Answer 31

-Isovolumetric contraction- contraction of ventricles that doesnt result in corresponding volume change
-begins during the QRS complex
-short moment that takes place when all the valves are closed -> electrical activation of ventricles
-When left ventricular pressure exceeds left atrial pressure, the mitral valve closes

Question 32

P wave

Answer 32

-atria depolarize and contract
-ventricles are filling the whole time (even before atrial contraction)
-atrial contract further fills the ventricles

Question 33

T wave

Answer 33

-ventricles eject blood into arteries
-ventricular volume reaches minimum
-aortic pressures starts to fall as blood runs off into arteries

Question 34

First heart sound (S1)

Answer 34

-closure of the AV valves
-mitral valve closes slightly before the tricuspid
-ventricular pressure increases but volume is constant bc all valves are closed
-When ventricular pressure is greater than aortic pressure -> aortic valve opens (too much pressure= bursts open)
-blood rapidly ejects from the aorta
-atrial filling begins -> pressure increases
-End of phase -> ST segment-> beginning of T wave and the end of ventricular contraction (end of the QRS complex)
-T wave- ventricles begin to repolarize; blood is leaving the left ventricle bc the aortic valve is still open -> LV pressure decreases

Question 35

Second heart sound (S2)

Answer 35

-aortic valve closing
-closes slightly before pulmonic valve (AP)
-Aortic valve closes when left ventricle pressure falls below aortic pressure
-aortic valve closes -> aortic pressure curve shows a “blip” called the dicrotic notch or incisura
-All valves are closed -> no blood is getting ejected or filling -> this phase is called the isovolumetric phase since it is constant (no change in volume)

Question 36

Third heart sound (S3)

Answer 36

-rapid flow of blood from atria to the ventricles
-sound is normal to hear in children, but not adults
-In adults- suggests volume overload, as in congestive heart failure
-ADULTS: IF YOU HEAR A THIRD HEART SOUND (BLOOD FROM ATRIA → VENTRICLES)= BAD = CHF / REGURGITATION

Question 37

diastasis

Answer 37

-aka reduced ventricular filling
-longest phase in the cardiac cycle
-final portion of ventricular filling
-occurs at a SLOWER RATE than in the previous phase
-If diastasis is reduced by increase in heart rate -> ventricular filling will be compromised -> end diastolic volume will be reduced -> stroke volume will also be reduced (frank starling relationship)

Question 38

CO VENTRICLES

Answer 38

ARE EQUAL
-what comes in must come out
-right ventricle lower pressure- ~25