Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Computational Cardiology > Introduction to the Cardiovascular System > Flashcards

Introduction to the Cardiovascular System Flashcards

1
Q

Main functions of the heart

A

provide the force necessary to pump oxygenated blood and nutrients throughout the body, maintain blood pressure and blood flow, receive deoxygenated blood and CO2 from the body and pump it to the lungs for reoxygenation and exhaling of CO2, generate hormones (ANF) and circulate this and other vital substances to different parts of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Main functions of the circulatory system

A

To transport nutrients, gases and waste products around the body, to help regulate blood pressure and blood flow to tissues as movement or metabolic demands change (exercise, position, blood loss), to protect the body from blood loss and infections, to help the body maintain a constant body temperature, to help maintain fluid balance within the body, humoral communication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Electrical impulses are normally initiated in the

A

Sinoatrial (SA) node

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

From the SA node, the waves of depolarization propagate along

A

three internodal tracts (anterior, middle, and posterior) across the right atrium to the atroventricular node (AV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The AV node

A

delays the electrical signal for ~120 msec to allow the atria to empty of blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

From the AV node, the wave of excitation

A

continues down the bundle of His or atrioventricular bundle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The bundle of His consists of

A

wide, fast-conducting muscle fibers that carry cardiac impulses through the insulating annulus fibrosis in the fibrous upper part of the ventricular septum, after which it bifurcates to become the left bundle branch and the right bundle branch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

These branches carry

A

the electrical signal to the Purkinje fibers, which are specialized conducting fibers that are composed of electrically excitable cells that are larger than cardiomyocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

His-Purkinje System

A

No electrical connection between atria and ventricles other than the Bundle of His

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The Purkinje Fibers conduct

A

cardiac action potentials more quickly and efficiently than any of the other cells in the heart’s electrical conduction system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Consequences of inappropriate conduction

A

Arrhythmias

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Cardiac myocytes (cardiomyocytes)

A

basic unit of contraction in the heart (20-50 um - 100-200 um) (mononucleated or binucleated)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Sarcolemma

A

maintains the intracellular milieu, transports substrates into and out of the cell, serves as a location for intracellular and extracellular proteins to attach, transmits excitatory impulses that lead to contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Major sarcolemma proteins

A

Na-K ATPase, L- and T-type calcium channels, Na-Ca exchanger, Na channels, K channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Three types of membrane junctions exist within an intercalated disk

A

Fascia adherens (intermediate junction), macula adherens (desmosomes), gap junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

These adhesion junctions

A

mechanically stabilize the sarcolemmas of adjacent cells allow formation and maintenance of large arrays of intercellular channels (gap junctions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Fascia adherens and desmosomes are characterized by

A

a much wider intermembrane space (25nm) than that of gap juction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Intercalated disks (ICDs) are

A

highly organized components of cardiac muscle which maintain structural integrity and synchronized contraction of cardiac tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Fascia Adherens (Adherecs junctios)

A

broad intercellular junction both of sarcolemma and intercalated disc, are anchoring sites to the actin cytoskeleton important for the maintenance of tissues and connect to the closest sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Desmosomes

A

macula adherens prevent separation during contraction by binding intermediate filaments joining the cells together

critical adhesion structures in cardiomyocytes, mediate direct cell-cell contacts, provide anchorage sites for intermediate filaments (desmin) important for maintenance of tissue structure, prevent the cells from pulling apart during the stress of individual fibers contracting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Gap Junctions

A

electrically couple cardiac myocytes and serve as low resistance electrical pathways that ensure safe conduction and allow the heart to function as an electrical sycytium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Sarcoplasmic Reticulum in cardiomyocytes

A

close association with T-tubules, form Dyad Junctions, sarcotubular network (transverse SR) and Cisternae (junctional SR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Major proteins involved in Ca++ flux

A

sarco(endo)plasmic reticulum ATPase, Phospholamban, Calsequestrin, SR calcium release channel (ryanodine receptor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Three filaments

A

Thick-myosin, thin-actin, elastic-titin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Arteries regulate inner diameter by

A

contraction of smooth muscle cells (tunica media)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Venous valves

A

prevent backflow of venous blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Vascular Smooth Muscle Cells

A

predominant cellular component found within tunica media
no pacemaker activity
under control of autonomic nervous system and stretch generally cannot cause contraction
regulate vascular tone
maintain structure of blood vessel
thickest in largest arteries, absent in capillaries, thin in veins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

General structure of smooth muscle cells

A

are small, mononucleated, fusiform (spindle) shaped cells, arranged circumferentially

end to end junctions couple the cells, increased surface area for both mechanical tight junctions and electrical coupling via gap junctions

do not contain the complex t-tubule/sarcoplasmic reticulum system common to striated muscles (no dyads), contain caveolae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Gap junctions in vSMCs

A

no intercalated discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

The aorta

A

a sparsely innervated and electrically quiescent vascular tissue that may be largely dependent on intercellular communication through gap junctions for coordination of smooth muscle responses

31
Q

Small muscular arteries are innervated to

A

regulate blood flow and pressure

32
Q

Synchronization of vasomotor tone among the smooth muscle cells is

A

critical for the function of blood vessels

33
Q

The vascular gap junctions are assembled from one or more of four connexin proteins

A

Cx37, Cx40, Cx43 (predominant form in vasculature), and Cx45 (only in SMCs of vasculature)

34
Q

Dense body

A

analogous to the Z-discs of skeletal and cardiac muscle fibers and is fastened to the sarcolemma, actin filaments are anchored to them

35
Q

The “Latch” mechanism

A

facilitates prolonged holding of contractions of smooth muscle (prolonged tonic contraction for hours with little use of energy)

36
Q

Electrical versus pharmacomechanical coupling

A

Calcium can enter the SM cell two ways

electrical depolarization results in increased Ca entry via the voltage gated channels

Receptor-coupled stimulation involves G-coupled receptors to release calcium from intracellular stores. No electrical activation required

37
Q

Layers of smooth muscle cells line

A

the walls of various organs and tubes in the body, and the contractile function of smooth muscle is not under voluntary control

38
Q

Contractile proteins

A

actin and myosin are not organized in a sarcomere structure, but form strut-like cables that alter force

39
Q

Contractile activity in smooth muscle is initiated by

A

a Ca++ calmodulin interaction to stimulate phosphorylation of the light chain of myosin-phosphorylation sensitizes the myofilament to calcium

40
Q

Ca++ sensitization of the contractile proteins

A

is signaled by the RhoA/Rho kinase pathway to inhibit the dephosphorylation of the light chain by myosin phosphatase, thereby maintaining force generation

41
Q

Relaxation is

A

mediated primarily by the activity of MLC phosphatase

42
Q

Calcium entry is

A

via voltage, receptor-coupled, or stretch activated channels triggers constriction

43
Q

Removal of Ca++ from the cytosol and stimulation of myosin phosphatase (and desensitization of the contractile protiens)

A

initiate the process of smooth muscle relaxation

44
Q

Potassium exit via several types of regulated channels triggers

A

relaxation or causes hyperpolarization to inhibit activation

45
Q

What is a capacitor?

A

a charge storing device

two conductors separated by an insulator

46
Q

What is capacitance of parallel plate capacitors?

A

Capacitance is determined by the overlapping plate area (A), the distance (d) between the conductors (plates), the permittivity (e) of the insulator

C = eA/d

47
Q

The charge Q on the plates is

A

proportional to the potential difference V across the two plates

48
Q

Capacitance C

A

the ability to store charge and it is the proportional constant Q = CV, C = Q/V

directly proportional to the area of the plate

inversely proportional to the distance between the plates

49
Q

Lipid Bilayer as a capacitor

A

As positive charge builds up on the inside of the membrane, they repel positive charges away from the outside of the membrane. Basically, an electric field over a distance corresponds to a voltage difference

50
Q

Electric field

A

the difference between the excess positive charges and the excess negative charges on the two membranes

51
Q

The separation of charges across a membrane

A

produces a potential difference between the two sides

52
Q

The displacement of charge

A

occurs due to a Capacitance current (Ic) through a membrane deltaQ = CdeltaV where Ic(t) = dQ/dt = C * dVm/dt

53
Q

Kirchoff’s 1st law

A

the current flowing into a node (or a junction) must be equal to the current flowing out of it : -Ic + Ie = 0 –> the sum of all currents into a node is zero

54
Q

From the capacitance current (deltaQ = C*deltaV), the total change in Voltage is given by

A

deltaV = 1/C * deltaQ

55
Q

Since I(t) is equivalent to dQ/dt, then Vm(t)

A

= V0 + I0/C*t

56
Q

Ie (electric current) =

A

IL (membrane ionic current) + CdV/dt (membrane capacitive current)

57
Q

Ohm’s Law

A

Vm = RL * Ie

58
Q

V(t) =

A

V(infinity) + (V0 - V(infinity))e^(-t/tau)

59
Q

tau

A

defined as the product RC (resistance and capacitance of the membrane)

60
Q

Conductance G

A

= 1/R

61
Q

Conductances in parallel

A

add together

62
Q

IL

A

= GLVm = AgLVm

63
Q

gL

A

specific membrane ‘leak’ conductanceA

64
Q

A

A

membrane area

65
Q

Positive currents

A

outward currents

66
Q

Negative currents

A

inward currents

67
Q

Capacitance in parallel also add and scales with area

A

C = CmA, A = 4pir^2

Cm = specific capacitance/unit area of membrane

A = area

68
Q

Membrane time constant

A

taum = RLC = C/GL = cmA/gLA = cm/gL

69
Q

tau is only

A

a property of the membrane, and it is not dependent on cell size

70
Q

What is the weakness of this cell system?

A

it relies on external curret

RL = leak resistance
Ie = injected current
IL = leak current from channels
Ic = capacitive current

71
Q

By having a battery, we have the basis for the HH model where

A

some ion channels push the membrane potential to be positive

some ion channels push the membrane potential to be negative

the voltage difference among all these currents is the ‘battery’. moreover, the additive effects of these channels/currents give the cells machinery that is flexible to control Vm

72
Q

Fick’s first law

A

Movement of particles (diffusion flux) from high to low concentration is directly proportional to the particle’s concentration gradient

J = -D (change in concentration of the particle)/(change in position) = -D (concentration gradient of the particle)

In one dimension: the molar flux of diffusion is proportional to the negative of the concentration gradient, a positive J is in the direction of the negative spatial slope of the concentration

73
Q

Fick’s Second Law

A

States the relation between the change in concentration gradient of the particles and time

change in concentration with time = D * it’s second derivative

relates changes in concentration with time with the spatial distribution of solute particles ie. it allows one to determine concentration as a function of time and position (C(x, t))

Flux = -P(C2-C1)
P = permeability, C2-C1 = difference in concentration

74
Q

Flux J

A

J = D/(kTfC) where f is the force per molecule, k is Boltzmann’s constant (R/No), R is the gas constant, N is the number of moles of the gas, T is the absolute temperature, C is concentration

Computational Cardiology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions