General, Week 1 Cardio Block2 Flashcards
1
Q
blood vessels only have direct _____________ innervation. what does this cause?
A
sympathetic, vascoconstriction
2
Q
aldosterone (adrenal gland) is secreted in response to:
A
angiotensin II or high serum potassium levels
3
Q
how can velocity of blood vary under constant flow? what is the deciding factor/equation?
A
Q = V x A
if there is a larger cross sectional area (capillaries), the blood will move slower
4
Q
where are continuous capillaries found?
A
skeletal and cardiac muscle, skin, lung, CT, brain (BBB)
5
Q
between the endocardium and myocardium lies the _________ ________, which houses what?
A
subendocardial layer
nerves, blood vessels, and Purkinje fibers
6
Q
opening of the mitral valve _________ opening of the tricuspid valve
opening of the aortic valve ________ opening of the pulmonic
A
precedes (activation of LV occurs first, pressure increases in L ventricle)
follows (less pressure to overcome in the pulmonary arteries)
7
Q
what does activation of alpha-2 adrenergic receptors do?
A
usually act presynaptically to inhibit NE release
RELAXES GUT
in low dose decreases BP
8
Q
what are the three ways you can regulate a patient’s contractility as a physician?
A
- ANS
- HR (independent of ANS)
- Cardiac gangliosides
9
Q
cardiac muscle cells (in myocardium) are started, _______, central nuclei, and have ________ ________
A
branches
intercalated disks
10
Q
what is the event that causes the closing of the mitral valve?
A
the ventricles are exciting, leading to contraction and a HUGE increase in ventricular pressure. This exceeds aortic pressure, closing the mitral valve
11
Q
the parasympathetic preganglionics are derived from where?
A
CN 3, 7, 9, 10 and sacral part of spinal cord
12
Q
when the cardiac muscle cell AP is more positive than the Na/Ca exchanger equilibrium potential, calcium flows (into/out of) cardiac muscle cell
A
into
13
Q
in smooth muscle, what allows for adaption to a new length? (think uterus)
A
filaments are dynamically repositioning their alignment and changing their number with stretch
14
Q
List the three transport mechanisms involved in lowering cytosolic calcium:
A
- SERCA Ca++ ATPase (back into SR)
- PMCA Ca++ ATPase (through plasma membrane)
- Na/Ca pump
15
Q
Conduction velocity is directly related to (2):
Indirectly related to: (2)
A
Directly = cross sectional area of the fiber, rate of rise of action potential
Indirect = resistance (number of gap junctions), and current needed to discharge capacitance (largely ignored)
16
Q
what are the determinants of cardiac output?
A
HR and SV
17
Q
epinephrine binds to which adrenergic receptors?
A
alpha1, alpha2, beta1, beta2
18
Q
what characterizes the absolute refractory period in ventricular cells?
A
the inactivation of VG Na+ channels
they need to get back down to a specific voltage to open (around -65 mV)
19
Q
where are fenestrated capillaries found?
A
glomerulus, synovium, endocrine glands, intestinal mucosa, choroid plexus
20
Q
SA node cells:
size?
resistance?
action potentials?
conduction velocity?
A
small, intracellular resistance high (little gap junctions), action potentials small and sloe
SLOW speed of conduction
21
Q
what factors affect resistance in a vessel? (3)
A
- viscosity
- length
- radius
22
Q
conduction system cells
size?
resistance?
action potentials?
conduction velocity?
A
very large cells
very low resistance
large/fast APs
VERY large conduction velocity
23
Q
name the three layers (think histo) of the heart
A
- endocardium
- myocardium
- epocardium (visceral pericardium)
24
Q
on ejection, radius of a chamber _______ and tension _________
what does this do to chamber pressure?
A
decreases, tension remains constant
it increases chamber pressure (P = 2HT/r)
25
murmurs are simply _______ blood flow in a vessel
turbulent
26
what mediates a ventricular cell action potential upstroke?
increase in Na+ permeability
| VG Na+ channel
27
volume of blood that leaves the L ventricle per minute =
cardiac output
28
store operated calcium channels in smooth muscle are activated when ________________________. They induce what two events?
SR Ca++ levels are depleted
1. restore SR calcium levels
2. activates contraction
29
the sympathetic preganglionic fibers are derived from what areas?
from thoracic and lumbar divisions of spinal cord
30
the lacrimal glands are only innervated by the __________ NS
parasympathetic
31
how does NE increase contractility?
(think signal transduction and 2 main things it phosphorylates)
what do they phosphorylations do ultimately in the cell?
NE --> beta-1 --> Gs --> cAMP --> PKA
```
phosphorylates VG Ca channel to let more in
phosphorylates phospholamban (to increase SERCA activity)
```
enhances Ca++ influx and results in increased loading of Ca into SR (INCREASES AVAILABILITY CA)
32
what comprises the L margin of the heart?
arch of the aorta
pulmonary trunk
L atrium
L ventricle
33
what do cardiac gangliosides do cellularly?
what does this mean for cardiac contraction
inhibits Na/K ATPase... changing Na+ gradient
now, Na/Ca exchanger has calcium INFLUX almost ALL of systole
34
MLCK usually binds to Ca-CM... but this affinity is decreased when what happens?
what happens to tension?
when MLCK is phosphorylated (by PKA)
tension decreases
35
a decrease in MAP decreases renal arterial pressure, converting _______ to _______. This then converts _____________ (from the liver) to __________. Via ACE, this converts ____________ to __________.
prorenin --> renin
angiotensinogen --> angiotensin 1
angiotensin 1 --> angiotensin 2
36
name the valve between the R atrium and R ventricle
right AV valve (tricuspid)
37
preload definition
pressure of the L ventricle prior to contraction (closely related to volume of blood in L ventricle prior to contraction)
38
_______________ is compromised in diastolic heart failure due to the inability to accommodate larger volumes of blood (think pressure volume curves)
heterometric reserve
39
what is the muscle called of the R ventricle wall?
trabecular carnae
40
under resting conditions the _________ NS plays the largest role in the heart
parasympathetic
41
what is the purpose (very general - main goal) for extrinsic control of arteriolar diameter?
intrinsic control?
regulating MAP
matching organ blood flow to metabolic needs of that specific organ
42
what factors can cause edema? think about pressures.
Increase in hydrostatic pressure (arteriolar vasodilation, long term standing/sitting)
Decrease in oncotic pressure of capillaries (liver failure, malnutrition, late term pregnancy)
43
transcapillary SOLUTE exchange depends on what three things? which the most?
1. solute permeability
2. SA of exchange
3. concentration difference (capillary - intersitium)
3 is most important
44
name the 5 factors that enhance venous return:
1) cardiac contraction (suction)
2) sympathetically induced venous vasoconstriction
3) skeletal muscle activity
4) venous valves
5) respiratory activity
45
define a long QT syndrome
increased time between ventricular activation and re-polarization
delayed ventricular repolarization
46
the adrenal gland (on top of kidneys) is stimulated by the ______ nervous system to release ________
sympathetic, epineprhine
47
how can you increase the active pressure curve on a pressure/volume diagram of the heart? (i.e., make it so that you have higher possible pressures generated at any given volume)
increase contractility (Ca++ availability or sensitivity)
increase sarcomeres (hypertrophy)
48
decreased arterial compliance can lead to increased _________ ____________ and therefore ___________
systolic pressure
hypertension
49
the key EXTRINSIC factor of arteriolar tone is the ______________.
_____ receptors cause vasoconstriction
_____ receptors cause vasodilation
sympathetic NS
alpha-1
beta-2
50
the SA node is located at the junction of the _________ and the _________
the AV node is located where?
superior vena cava, R atrium
between R atrium and R ventricle
51
most arteries and arterioles are innervated only by __________ nerves that release NE. NE binds to ___________ receptors in the vascular smooth muscle. What does opening of this receptor do?
sympathetic
alpha-1 receptors
PKC --> IP3 --> Ca release from SR
52
repolarization of the nodal cell action potential is caused by what?
opening of delayed-rectifier K+ channels.
K+ efflux
53
describe the histology of a heart valve
a core of connective tissue lined on both sides by endocardium
54
On diastolic filling, radius of a chamber _________ and tension _________
what does this do to chamber pressure?
increases, increases (think rubber band)
keeps chamber pressure pretty constant
55
list the 4 phases of the cardiac cycle:
what valves are open at each one?
1. Filling phase (mitral and tricuspid valves open)
2. Isovolumetric contraction phase (both valves closed)
3. Ejection phase (aortic and pulmonic valves open)
4. Isovolumetric relaxation phase (both valves closed)
56
parasympathetics innervate the heart (at what locations) via the _______ nerve. What does this do to the heart?
SA/AV node, vagus nerve, decreases HR
57
what is the role of aldosterone?
sodium retention and potassium secretion by the kidneys
58
the Na/Ca exchanger in cardiac muscle cells usually mediates calcium _______, but transiently mediates calcium ______ during what phase of the cardiac cycle?
efflux, influx
early systole (rapid depolarization)
59
what characterizes the supranormal period in ventricular cells?
when the membrane potential is close to the resting membrane potential, there are enough Na+ channels available that if you give a stimulus, it would actually fire and create a normal action potential
even though the stimulus is less than what you usually need.
60
The more depolarized the rmp of a smooth muscle cell, the more _________ the cells are, the more hyperpolarized the rmp the more __________ the cells are
contracted, relaxed
61
At steady state HR, calcium ________ equals calcium _______ each beat. With an increase in HR... what happens?
influx, efflux
influx > efflux, increased Ca in SR... new steady state
more Ca for CICR, larger contractility
62
where are nicotinic cholinergic receptors located??
- all autonomic sympathetic and parasympathetic ganglia neurons (including adrenal medulla)
- NMJ
63
epicardium is the same as __________ _________
visceral pericardium
64
the left coronary artery branches into the ________ _______ and ______________ right away
circumflex branch, anterior interventricular artery
65
parasympathetics --> ______ ---> SA/AV nodes.
Heart rate slows by what two mechanisms?
Ach
1. ACh-gated K+ channels open
2. muscarinic receptors activated --> reduces cAMP and decreases effects of sympathetic activation
66
what is the principle determinant for how much volume ends up inside your ventricle?
the filling pressure (preload), the pressure required to establish the EDV
more preload pressure -> more filling
67
Ach, through muscarinic receptors, triggers _____ production, which diffuses into SM where it is __________
NO
vasodilatory
68
what is the equation for the resistance of a vessel?
what is the main deciding factor?
R = 8*viscosity*length/pi*r^4
the radius is the largest player
69
__________ muscle generates force over a much larger range of lengths than _________ muscle
smooth, skeletal
70
Afterload:
pressure the L ventricle has to overcome for the blood to be ejected
71
what does angiotensin 2 do? (5)
1. stimulates the adrenal gland to produce ALDOSTERONE
2. arteriolar vasoconstriction (increase TPR)
3. Increases Na+ reabsorption and K+ secretion in kidneys
4. activates sympathetics
5. increase ADH secretion
OVERALL - INCREASES MAP
72
what is net driving force?
oncotic pressure moves fluid _____ the capillaries. this is called _________ and has a net driving force of (> or
NDF=(Pc –Pi)–σ(πc –πi)
into, reabsorption, < 0
73
how do muscarinic cholinergic receptors decrease HR?
their activation opens K+ channels, hyper-polarizing cell for longer
also decrease PKA activity, halting all of those phosphorylation channel effects from the sympathetics
74
how can you modulate stroke volume?
increase venous return (EDV) and ventricular contractility (sympathetics)
75
describe the fibrous skeleton of the heart:
4 dense CT rings that support the 4 valves
cardiac muscle cells attach
76
in a tube with a _________ radius, there is less resistance and ________ blood flow (mL/min)
smaller
increased
77
what structural part of the heart has the highest conduction velocity? lowest?
highest: Purkinje system, His, BB
lowest: AV node, then SA node
78
on isovolumetric contraction, radius of a chamber ___________ and tension __________
what does this do to chamber pressure?
remains constant, tension increases
this increases chamber pressure (P = 2HT/r)
79
what is the valve connecting the left atrium and left ventricle?
the left AV valve or MITRAL VALVE
80
the passive tension curve on the pressure/volume plot of the heart represents what?
the work being done on the heart by increasing blood filling at increasing volumes. pressure generated by filling the heart to a certain volume (no active work)
81
where are the locations of the baroreceptors?
what CNs do they travel with?
carotid sinus - glossopharyngeal (CN 9)
| aortic arch - vagus n. (CN 10)
82
why does edema occur? (general)
what factors can cause this?
the net filtration exceeds the ability of lymphatic drainage - excess of fluid in interstitial space
83
the cells of a ventricle and atria have a ten fold higher resting membrane permeability to ______ than do skeletal muscle or nerve cells due to the large number of ______ channels.
what is the result?
Potassium, Kir
stabilizes resting membrane potentials, decreasing likelihood of arrhythmias (need a large stimulus to stimulate cells)
84
what two things determine contractility of the heart? (2)
1. Availability of calcium
| 2. Sensitivity to calcium
85
what is the basis behind valves opening?
pressure differences across compartments
86
when the cardiac muscle cell AP is more negative then the Na/Ca exchanger equilibrium potential, calcium flows (into/out of) the cell
out of
87
what are the ways cytosol calcium can be increased in a smooth muscle cell via intracellular mechanisms? (2)
1. CICR from SR (VG Ca++ opening causes this, but that is extracellular)
2. IP3 mediated calcium release from SR
88
smooth muscle cells have a low permeability to:
potassium
89
what is the most predictable effect of alpha-1 adrenergic activation?
vasoconstriction of arteries and veins
increase TPR, increase venous return
--> increase BP
90
ejection fraction:
percentage that leaves the L ventricle
91
what is a ventricular cell resting membrane potential?
-80 to -85 mV
| high resting K+ efflux, high ATPase level contributes
92
on isovolumetric relaxation, the radius of a chamber ___________ and tension _________
what does this do to chamber pressure?
radius remains constant, decreases
it decreases chamber pressure (P = 2HT/r)
93
Low K permeability in SMCs means other permeability pathways more easily do what?. Consequently, the resting membrane potential of smooth muscle cells is typically around _______.
draw the membrane potential away from EK
-45 mV
94
most of the blood volume is found in the _______ and _______ at any point in time. they have a large ________, which allows them to expand volume at a given pressure
veins and venues
compliance
95
sweat glands are mediated by the __________ NS but have ________ receptor activation
sympathetic, cholinergic
96
the blood pressure does not decrease from the arteries to veins in a linear manner. the largest drop of blood pressure is in the ____________. Here, blood flow to the various organs is controlled.
arterioles
97
the smooth surface that accompanies the vena cava and continues into a portion of the atrium is derived from what embryological feature?
sinus venosus
98
what are the determinants of FORCE in the heart (2)? (since all cells fire together)
1. length-tension
| 2. Contractility (modulate Ca++ availability)
99
the _________ muscles attach to the flaps of the tricuspid valve via _____________. What are the purpose of these muscles?
papillary, via the chordae tendinae
to keep the valve from prolapsing back into the atria during contraciton
100
what do indirect cholinergic stimulating drugs do?
inhibit destruction of ACh by the enzyme acetylcholinesterase, increasing concentration of ACh.
101
what is the equation for cardiac efficiency?
Cardiac Efficiency = SW / QO2
102
what structural feature of smooth muscle cells accommodates the broad range of lengths over which smooth muscle cells can function?
loose organization of actin and myosin filaments (myosin light chains aren't even anchored)
what it interacts with depends on what actin filament is nearest!!
103
vascular smooth muscle has ____ and ____ adrenergic receptors. the first ____________ and the second __________
alpha-1, beta-2
vasoconstricts
vasodilates
104
an increase in venous tone, peripheral vascular pressure _________ and venous return _________
increases, increases
105
the blood flow (mL/min) in a vessel is directly proportional to the ___________ and inversely proportional to the __________
pressure gradient
resistance
106
what is usually the cause of a long QT interval?
mutations in genes comprising the delayed-rectifier K channels causing delayed activation and making repolarization occur later
107
where are discontinuous capillaries found?
liver, bone marrow, spleen
108
volume of blood that leaves the L ventricle per beat
stroke volume
109
a low blood pressure would affect the baroreceptors, _________ their firing rate. This would activate the ____________________. What is the ultimate result?
decreasing
sympathetic NS
increase sympathetics to cardiac - HR and contractility, vasoconstrict (DIRECT - from activation of sympathetics - this is unlike the parasympathetics)
110
____________ increase CO by increasing BOTH heart rate AND stroke volume
parasympathetics
111
the muscle of the right atrium is called the _________ muscle. the muscle and smooth surface of the atrium are separated by the ____________ internally
pectinate muscle
crista terminales
112
nerves going to the heart (both sympathetic and parasympathetic) enter the _______ ________. The parasympathetics come from the _______ nerve and are preganglionic.
cardiac plexus
| vagus
113
Nodal cell AP: I funny channels are activated by ____________ and are ___________ ___________ channels that let in ______, __________ the cell
hyperpolarization
non-specific cation channels
Na+
depolarizing
114
Stretch-activated channels in smooth channel: non-selective cation channels – tend to _________ m.p. causing ___________
depolarize, causing contraction
115
adrenergic receptors (sympathetics):
alpha receptors are generally _________ except in _____
beta receptors are generally _________ except in _______
excitatory, gut
inhibitory, heart
116
what are the ways cytosol calcium can be increased in a smooth muscle cell via extracellular mechanisms? (4)
1. VG Ca++ opening (L-type Ca channel)
2. Store-activated Ca++ channel (activated when SR calcium stores are low)
3. Non-selective cation channels - let in Na+ and Ca2+
(stretch or ligand)
117
what does activation of beta-2 adrenergic receptors do?
vasodilator (especially in skeletal muscles) --> decrease TPR --> drop BP
bronchodilator
118
a more compliant vessel can hold more _________ at a certain __________
state the equation for compliance
volume, pressure
C = delta V/ delta P
119
what causes the plateau phase of the ventricular action potential?
1. an increase in Ca++ permeability (l-type calcium channels)
2. Magnesium blocking of Kir channels, decrease in K+ efflux.
The hyperpolarizing and depolarizing effects cancel out, leaving mp at 0 mV for an extended period of time
120
NE binds to which adrenergic receptors?
alpha1, alpha2, beta1
121
unitary smooth muscle has ______ gap junctions
what are it's 3 properties?
give examples of locations of unitary smooth muscle
1. syncytial behavior
2. respond to stretch with increased activity
3. low to moderate innervation density
hollow organs, blood vessels, uterus, gut
122
homeometric regulation of contractility is governed by:
| heterometric regulation of contractility is governed by:
homeometric - change in contractility (independent of changes in length)
heterometric: length-tension (changes in sarcomere length)
123
sympathetic fibers release ____ and bind to _____ adrenergic receptors on the ventricles, activating _ _ _.
What does this do to the ventricular AP?
NE, beta, PKA
phosphorylates calcium channels, slow and fast delayed-rectifier K+ channels
shorten AP duration
124
purkinje fibers of the heart are derived from:
what do they look like in histo?
cardiac myocytes
wide-diameter, "puffy", few sarcomeres, connected by gap junctions electric)
125
long term regulation of MAP through blood volume is done through the:
renin-angiotensin-aldosterone system
126
the upstroke of the nodal action potential is caused by what?
increase in Ca++ permeability (L-type VG)
127
why are smooth muscle cells sensitive to small changes in membrane permeabilities?
The overall low permeability of smooth muscle cells to ions, but K in particular. Easier to pull membrane potential farther from Ek
our rmp is really so close to the Ca-L channel activation threshold - small permeability changes really signficicanly change contraction
128
the right and left bundle branches off the bundle of His are composed of ______ _________ in the __________ _________
purkinje fibers
subendocardial space
129
sympathetics innervate what part of the heart?
what does it cause?
the SA/AV nodes, L ventricle
increase in HR AND contractility
130
when thinking about transcapillary FLUID exchange, oncotic pressure tends to favor movement _______ the capillaries while hydrostatic pressure tends to favor movement ______
into
out
131
in pharmacomechanical coupling for smooth muscle activation cytosolic Ca2+ is controlled by:
1. ___________- induced Ca2+ release from ___________ (change in membrane potential not necessary)
2. and/or _____________________________
1. second messenger- induced Ca2+ release from internal stores
2. change in sensitivity of filaments to Ca2+ via phosphorylation
132
The range of volumes over which an increase in volume results in increased active pressure due to optimization of thick-thin filament overlap in sarcomeres
heterometric reserve
133
what event on the Wiggers diagram marks the end of ventricular diastole and start of ventricular systole? (L heart for example)
Closure of mitral valve (go into isovolumetric contraction phase)
134
when the cardiac muscle cell AP is more negative then the Na/Ca exchanger equilibrium potential, calcium flows (into/out of) the cell
out of
135
the openings for the coronary arteries are in the:
sinuses of the aortic valves
136
the right marginal artery comes from the ________ __________ _________
right coronary artery
137
epinephrine ________ ventricular action potential by increasing opening probability of _______ and ______ channels and increasing permeability
shortens
delated-rectifier K+ channels (fast and slow)
L-type Ca++ channels
138
ACE stands for what and does what?
angiotensin converting enzyme
angiotensin 1 --> angiotensin 2
139
EMBRYOLOGY HERE
m
140
what is the equation for how much pressure a chamber can develop?
P = 2HT/r
```
H = thickness
T = tension
r = radius of chamber
```
141
what phases of the cardiac cycle are considered diastole?
1. isovolumetric relaxation phase
| 2. filling phase
142
__________ - determines volume and therefore sarcomere length; can change suddenly
___________ - determines how much work the heart must do to successfully eject blood
preload
afterloas
143
what activates myosin light chain kinase? (MLCK) in smooth muscle
`its binding to Ca-CM (calcium calmodulin)
144
what does activation of beta-1 adrenergic receptors do?
Increase HR
Increase contractility
Increase lipolysis
Increase renin secretion
145
____________ is a measure of distensibility of a vessel
compliance
146
the difference between diastolic and systolic pressures is called:
pulse pressure
147
what is the equation for the total energy needed by the heart in systole?
Qo2 = Stroke Work (SW) * Tension heat
148
in multiunit smooth muscle, there are ____ gap junctions
coordinated movements are usually _______ mediated and there is an ________ of neural connections.
examples of multiunit smooth muscle in the body
no gap junctions
neurally
abundance of neural connections
pilomotor cells for body hair, iris, ciliary body
149
what phases of the cardiac cycle are considered systole?
1. isovolumetric contraction phase
| 2. ejection phase
150
what does NE do to the ventricular action potential in terms of membrane proteins? in terms of length of AP?
PKA --> phosphorylates L-type Ca++ channel (opening them sooner and increasing flow --> Ca induced inactivation)
phosphorylates fast and slow Kv channels --> increase probability of opening (and thus repolarization)
decrease ventricular AP
151
sympathetic (NE) input to nodal cells causes _________ in rate of AP. How does it do this (think 3 channels)?
Increase
Enhances activity of I funny channels (increase opening probability, faster depolarization)
Increases permeability in delayed-rectifier Ca++ channels (quickens re-polarization)
Increases permeability of L-type Ca++ channels (brings depolarization up faster and stronger but also turns off faster)
152
an increase in __________ increases the end diastolic volume
an increase in _________ decreases the end systolic volume
an increase in _________ increases the end systolic volume
preload
contractility
afterload
153
what is the equation for pressure in a compartment?
P = 2HT/r
154
where are muscarinic cholinergic receptors located?
- postganglionic parasympathetic effector cells
| - other effector cells (blood vessels - not connected to cholingeric innervation)
155
the ___________ ________ is a branch off the trabecular carnae and is important for the conduction system into the ventricles
moderator band
156
what is the equation for stroke work?
definition?
stroke work (SW) = work done on the blood by the heart
SW = Pafterload * SV + 1/2mv2
157
the __________ must be phosphorylated before it can interact with actin in smooth muscle to form cross bridges
what phosphorylates it?
myosin light chain
Ca-CM-MLCK
158
when MLC is dephosphorylated while in the attached state, there is:
tension maintenance at low energy exposure
159
the predominant chamber viewed on an anterior view is the:
R ventricle
160
the resting permeability of cells in the ventricles, atria, and ventricular conducting system are determined by what?
potassium permeability mediated by Kir channels
161
Sustained increase in preload is met with sustained increase in SV principally through increased _____________
contractility (ANS)
162
KIR-type channels in smooth muscle tend to ______________ m.p. causing ____________
hyperpolarize, causing relaxation
163
MAP is closer to the _______ pressure than the _______ pressure... why?
diastolic, systolic
more time is spent in diastole
164
in active muscle and heart, the constrictive effects of adrenergic stimulation are overwhelmed by _______ effects of ___________
dilated
metabolites (released by the working muscle)
165
when more volume comes into a chamber, this _________ the sarcomeres, increasing _________ of pressure to be generated
more volume = _______ pressure (potentially)
lengthens, ABILITY
more volume = more potential pressure (active pressure curve)
166
the T wave comprises the time between __________ of epicardium and ___________ of endocardium
repolarization
167
why does smooth muscle have a baseline "tone", or a steady level of contractile tension.
the membrane potential lies near the Ca-L channel activation threshold (-40-45 mV), some Ca++ is coming in, baseline tone
168
Blood pressure is regulated by controlling _________, ______________,
and ________________
cardiac output
total peripheral resistance
blood volume
169
explain the cardiac suction of the heart
During ventricular contraction, the AV valves are drawn downwards, enlarging the atrial cavities. Thus the atrial pressure drops below 0 mm Hg
larger pressure difference
170
what channels are the players in the pacemaker potential phase of nodal action potentials? (5)
0. Delated-rectifier K+ channels close
1. If - I funny channels opens
2. Na/Ca exchanger
3. T-type Ca++ channels open
4. L-type Ca++ channels open
171
P-wave:
QRS-complex:
T-wave:
atrial depolarization
ventricular depolarization
ventricular repolarization
172
Receptor operated channels in smooth muscle (electromechanical stimulation of SMCs): usually non-selective cation channels – tend to _________, causing __________
depolarize, causing contraction
173
a high blood pressure with activate the __________, increasing their firing rate. This would activate the ____________________ and inhibit the ________________. What is the ultimate result?
baroreceptors
parasympathetic NS
sympathetic NS
decrease HR (direct), reduce contractility and vasodilate (indirect, via inhibiting sympathetics)
174
the active pressure curve on a pressure/volume plot of the heart represents what?
the maximum pressure the heart my produce actively at a give volume (optimizing sarcomere length here)
175
what is net driving force?
hydrostatic pressure pushes fluid _____ of the capillaries. this is called ______ and has a net driving force of ___ (< or >) than 0
NDF=(Pc –Pi)–σ(πc –πi)
out, filtration, > 0
176
what are the structures in the R margin of the heart?
the superior vena cava
R atrium
inferior vena cava
177
what causes repolarization in ventricular cell action potentials?
1. opening of delayed-rectifier K+ channels
(can be rapid or slow)
2. Ca++ channels (L-type) inactivate
3. Mg2+ block on Kir channels leaves after sufficient re-polarization (K+ efflux, hyperpolarization)
178
the pericardium, or pericardial sac includes the ______ pericardium, which is actually the outer layer of the heart. And the _____ pericardium, which attaches to the thoracic wall
visceral, parietal
179
the bases of heart valves are connected to rings of the _______ _________ that surround the valve opening
fibrous skeleton
180
dephosphorylation of MLC (myosin light chain) in smooth muscle is mediated by what?
what does this cause?
what is this regulated by?
MLC phosphatase
inability of myosin to form cross bridges with actin --> relaxation of smooth muscle
cGMP
181
what is the adjustable factor that is the prime determinant of resistance?
arteriolar radius
182
________ is the major determinant of the total energy requirements of the heart!
tension (heat)
183
why are manifestations of a long QT interval triggered by physical exercise?
Increased HR --> but patient has failure to shorten the ventricular action potential --> decreases filling --> reduced cardiac output when demand is high
184
the valve for the coronary sinus is seen in the _____ _______ (what chamber)
right atrium
185
The refractory periods ensure a _________ nature of the heart and the ability to ______
pulsatile, fill
186
MAP = _____ x ______
CO x TPR
187
on nodal cell pacemaker potential.... VG T-type calcium channels are activated. As Ca+ enters cell, triggers the ___________ to get rid of the Ca++, bring in __ ______, contributing to _________.
Na/Ca Exchanger, 3 Na+ into the cell
| depolarization
188
what event on the Wiggers diagram marks the end of ventricular systole and start of ventricular diastole? (L heart for example)
closure of the aortic valve (go into isovolumetric relaxation phase)
189
the moment to moment control of the MAP is achieved through the ________ reflex - which changes ____ and ____ to change MAP
baroreceptor
CO and TPR
190
equation for cardiac output = _____ x _____
HR x SV
191
what is the characteristic feature of the ventricular action potential (a phase)?
the plateau phase
192
tension in smooth muscle _______ when cGMP activates ___________
tension in smooth muscle _______ when cAMP activates _______ to phosphorylate MLCK
decreases, MLC-phosphotase
decreases, PKA
193
inotropy:
force of contraction
194
in what cell action potential is there no period in time that the membrane potential is constant?
in nodal cell action potentials
195
actin and myosin are _______ organized in smooth muscle, the thin filaments (actin) are organized into bundles and anchored to ________ ________
loosely
dense bodies
196
function of the lymphatics (4);
1. return excess interstitial fluid to venous system
2. immune defense
3. transport of absorbed fat
4. return of filtered protein to vasculature
197
complete the flow chart:
sympathetics --> NE --> B1 in nodal cells --> increase _____ --> activate ____ ---> increase activity of ________ channels --> ultimately _______ HR
increase cAMP
activate PKA
increase I funny channel activity
decrease HR
198
what are the 4 benefits to the parallel circuitry of the peripheral circulation?
1. overall resistance reduced, less afterload
2. All organs receive same oxygenated blood, no "leftovers"
3. common perfusion pressure - can all regulate their own
4. protects against injury upstream
