Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Computational Cardiology > Introduction to the Cardiovascular System > Flashcards

Introduction to the Cardiovascular System Flashcards

(74 cards)

Start Studying
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
Arteries regulate inner diameter by
contraction of smooth muscle cells (tunica media)
26
Venous valves
prevent backflow of venous blood
27
Vascular Smooth Muscle Cells
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
28
General structure of smooth muscle cells
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
29
Gap junctions in vSMCs
no intercalated discs
30
The aorta
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
Small muscular arteries are innervated to
regulate blood flow and pressure
32
Synchronization of vasomotor tone among the smooth muscle cells is
critical for the function of blood vessels
33
The vascular gap junctions are assembled from one or more of four connexin proteins
Cx37, Cx40, Cx43 (predominant form in vasculature), and Cx45 (only in SMCs of vasculature)
34
Dense body
analogous to the Z-discs of skeletal and cardiac muscle fibers and is fastened to the sarcolemma, actin filaments are anchored to them
35
The "Latch" mechanism
facilitates prolonged holding of contractions of smooth muscle (prolonged tonic contraction for hours with little use of energy)
36
Electrical versus pharmacomechanical coupling
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
Layers of smooth muscle cells line
the walls of various organs and tubes in the body, and the contractile function of smooth muscle is not under voluntary control
38
Contractile proteins
actin and myosin are not organized in a sarcomere structure, but form strut-like cables that alter force
39
Contractile activity in smooth muscle is initiated by
a Ca++ calmodulin interaction to stimulate phosphorylation of the light chain of myosin-phosphorylation sensitizes the myofilament to calcium
40
Ca++ sensitization of the contractile proteins
is signaled by the RhoA/Rho kinase pathway to inhibit the dephosphorylation of the light chain by myosin phosphatase, thereby maintaining force generation
41
Relaxation is
mediated primarily by the activity of MLC phosphatase
42
Calcium entry is
via voltage, receptor-coupled, or stretch activated channels triggers constriction
43
Removal of Ca++ from the cytosol and stimulation of myosin phosphatase (and desensitization of the contractile protiens)
initiate the process of smooth muscle relaxation
44
Potassium exit via several types of regulated channels triggers
relaxation or causes hyperpolarization to inhibit activation
45
What is a capacitor?
a charge storing device two conductors separated by an insulator
46
What is capacitance of parallel plate capacitors?
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
The charge Q on the plates is
proportional to the potential difference V across the two plates
48
Capacitance C
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
Lipid Bilayer as a capacitor
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
Electric field
the difference between the excess positive charges and the excess negative charges on the two membranes
51
The separation of charges across a membrane
produces a potential difference between the two sides
52
The displacement of charge
occurs due to a Capacitance current (Ic) through a membrane deltaQ = CdeltaV where Ic(t) = dQ/dt = C * dVm/dt
53
Kirchoff's 1st law
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
From the capacitance current (deltaQ = C*deltaV), the total change in Voltage is given by
deltaV = 1/C * deltaQ
55
Since I(t) is equivalent to dQ/dt, then Vm(t)
= V0 + I0/C*t
56
Ie (electric current) =
IL (membrane ionic current) + CdV/dt (membrane capacitive current)
57
Ohm's Law
Vm = RL * Ie
58
V(t) =
V(infinity) + (V0 - V(infinity))e^(-t/tau)
59
tau
defined as the product RC (resistance and capacitance of the membrane)
60
Conductance G
= 1/R
61
Conductances in parallel
add together
62
IL
= GLVm = AgLVm
63
gL
specific membrane 'leak' conductanceA
64
A
membrane area
65
Positive currents
outward currents
66
Negative currents
inward currents
67
Capacitance in parallel also add and scales with area
C = CmA, A = 4pir^2 Cm = specific capacitance/unit area of membrane A = area
68
Membrane time constant
taum = RLC = C/GL = cmA/gLA = cm/gL
69
tau is only
a property of the membrane, and it is not dependent on cell size
70
What is the weakness of this cell system?
it relies on external curret RL = leak resistance Ie = injected current IL = leak current from channels Ic = capacitive current
71
By having a battery, we have the basis for the HH model where
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
Fick's first law
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
Fick's Second Law
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
Flux J
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.
© 2025 Bold Learning Solutions. Terms and Conditions