Final Flashcards
(155 cards)
1
Q
Which vessels show greatest resistance to blood flow?
A
Arterioles
2
Q
Smallest vessels in the circulation
A
capillaries
3
Q
When the lumen of a blood vessel is suddenly expanded, the smooth muscles respond by contracting in order to restore the vessel diameter and resistance. The converse is also true. This is?
A
Autoregulation: Myogenic Mechanism
Proposed mechanism is stretch of vascular smooth muscle causes activation of membrane calcium channels.
4
Q
The _______, located in the brainstem above the spinal cord, is the primary site in the brain for regulating ________ and __________ (vagal) outflow to the heart and blood vessels.
A
medulla
sympathetic
parasympathetic
5
Q
Increased ICP results in increased BP until blood flows once again in the vessels of the brain. What response?
A
Cushing response
6
Q
The _______ of each tissue continuously monitor tissue needs
A
microvessels
7
Q
Blood flow =
A
pressure difference/resistance
pressure difference example: P.arterial - P.venous
8
Q
greatest role of all factors in determining the rate of blood flow through a vessel
A
diameter/radius
9
Q
Flow is Inversely proportionate to?
A
viscosity and length of tube
10
Q
SVR is primarily determined by changes in blood vessel________.
A
diameters
11
Q
sum of resistance vessels in a series?
A
totalresistanceto blood flow (Rtotal) is equal to the sum of theresistances of each vessel
R.t = R.1 + R.2 + R3, etc.
12
Q
sum of resistance vessels in parallel?
A
1/R.t = 1/R.1 + 1/R.2 + 1/R3, etc.
(Flow through each of the parallel vesselsis determined by the pressure gradient and its ownresistance, not theresistanceof the other parallel blood vessels. However, increasing theresistanceof any of the blood vessels increases the totalvascular resistance.)
13
Q
parallel arrangement permits each tissue to regulate its own blood flow, to a great extent, ___________ of flow to other tissues. Therefore, the totalresistanceis far ____ than theresistanceof any single blood vessel
A
independently
less
14
Q
A valuable characteristic of thevascularsystem is that all blood vessels are_______.
A
distensible
15
Q
This capability provides smooth, continuous flow of blood through the very small blood vessels of the tissues.
A
Distensibility/compliance
16
Q
Tissue Layers of Blood Vessels:
A
Intima (inner most)
Media
Adventitia (outer most)
17
Q
which layer of blood vessel thicker in arteries? Which is thicker in veins?
A
media
adventitia
18
Q
arterial compliance =
A
Change in volume/change in pressure
19
Q
Autoregulation:Metabolic Mechanism
A
When the pressure increases to a tissue, the flow increases, and excess oxygen and nutrients are provided to the tissues. These excess nutrients cause the blood vessels to constrict and the flow to return nearly to normal despite the increased pressure
20
Q
Vasoactive substances released from endothelium lining vessels?
A
- nitric oxide (dilator - MOST IMPORTANT)
- prostacyclin (dilator)
- endothelin (constrictor)
21
Q
-A key mechanism for long-termlocal blood flowregulation is to change the amount of vascularity of the tissues. For instance, if the metabolism in a tissue is increased for a prolonged period, vascularity increases.
-The generation of new blood vessels
A
Angiogenesis
22
Q
When an artery or a vein is blocked, a new vascular channel usually develops around the blockage and allows at least partial resupply ofbloodto the affected tissue. Called?
A
Collateral Circulation
23
Q
defined as theintrinsic ability of an organ to maintain a constant blood _____ despite changes in ________ pressure. What is this?
A
flow
perfusion
autoregulation (an intrinsic ability)
24
Q
what mechanisms responsible for autoregulation? (2)
A
- Myogenic
- metabolic
25
Which vessels have the greatest surface area for exchange?
capillaries
26
capillaries are missing what and incapable of what?
missing smooth muscle
incapable of contraction
27
Mechanisms of Exchange Across The Capillary Endothelium?
- Diffusion (Oxygen, Carbon Dioxide, Lipid-Soluble Substances)
- Bulk flow (Water, Electrolytes, Small Molecules)
- Active transport (Ions, Glucose, Amino Acids)
- Vesicular transport (Proteins)
28
mean pressure in capillaries
25-30
29
which layer of vessel contains nerves and nutrient capillaries?
adventitia/externa
30
Higher at the arteriolar end than at the venule end. Tends to force fluid outward through the capillary membrane.
Capillary hydrostatic pressure
31
This is usually an outward force for fluid movement.
Interstitial fluid hydrostatic pressure
32
What are the Starling Forces with regards to capillary filtration/reabsorption? (4)
- Capillary hydrostatic pressure (P.c)
- Interstitial fluid hydrostatic pressure (P.if)
- plasma colloid osmotic pressure (Pie.p)
- interstitial fluid osmotic pressure (Pie.if)
33
What is capillary reabsorption?
net movement of water from the interstitial space to the capillary
(net driving force < 0)
34
What is capillary filtration?
net movement of water from the capillary to the interstitial space
(net driving force > 0)
35
If Net Driving Forces are positive, does it favor capillary filtration or reabsorption?
Filtration
36
Are hydrostatic pressures within the capillary equal at the arteriolar end and the venous end?
No, pressures higher on arteriole side
37
Under normal circumstances, what Net Driving Force favors fluid movement INTO the capillary?
plasma colloid osmotic pressure a.k.a. plasma oncotic pressure (reabsorption)
38
What is the function of the lymphatic system? and what does it return to circulation? (4)
an accessory route through which fluid can flow from the interstitial spaces into the blood
Returns to circulation:
- Protein (Albumin)
- Bacteria
- Fat
- Excess fluid
39
How is plasma filtrate returned to the circulation by the lymphatic system? (4)
- Lymphatic vessel contraction
- Intermittent skeletal muscle activity
- System of one-way valves
- Tissue pressure
40
which of the two oncotic pressures have a greater force?
capillary plasma oncotic pressure (forcing reabsorption)
41
what does the increased concentration of protein along the capillary do? (2)
- increases capillary plasma oncotic pressure
| - Decreases NDF (net driving force)
42
Effect causing extra force in plasma protein?
Gibbs-Donnan Effect - cations in plasma creating extra pressure (9mmHg)
43
on which sides does filtration/reabsorption occur?
Fitration - Arteriole side
Absorption - Venule side
44
What does a decreased capillary hydrostatic pressure and increased oncotic pressure reveal?
Dehydration
| Lower NDF and longer Reabsorption period
45
Capillary hydrostatic pressure (P.c) in Arterioles vs Venules? and net driving forces?
30mmHg vs 10mmHg
15mmHg vs (-)5mmHg
46
What is the formula for coronary perfusion pressure?
Diastolic BP – LVEDP (or PCWP)
47
Does the majority of coronary blood flow occur during systole or diastole in the left ventricle? Why?
Diastole
Extravascular compression during systole markedly affects coronary flow
48
What is coronary flow reserve? how much max vs resting?
Difference between resting/baseline blood flow and maximal flow
maximal flow is 4 – 5 times as great as at rest
49
Do the major epicardial arteries contribute significantly to coronary vascular resistance?
no, myocardial vessels do
50
What are the major determinants of myocardial oxygen demand?
HR
Contractility
Systolic wall tension
51
What are the major determinants of myocardial oxygen supply?
Coronary blood flow
| O2 carrying capacity
52
Which layer of the myocardium is at greatest risk for ischemia? Why?
subendocardium
Epicardial coronary stenoses are associated with reductions in the subendocardial to subepicardial flow ratio
53
Which of the following places a greater oxygen cost on the heart? Pressure work versus volume work.
Pressures work
increasing arterial pressure at a constant cardiac output harder on heart
54
How stenotic do coronary vessels have to be before there is a significant decrease in flow?
60% occluded or 40% max Radius
55
What controls coronary blood flow?
Vascular resistance
56
What controls vascular resistance?
```
Neural control
Metabolic control
Endothelial control
Autoregulation
Extravascular compressive forces
```
57
Blood flow through the coronary system is regulated mostly by __________ ?
local arteriolar vasodilation
58
normal coronary blood flow?
- 70 ml/min/100 g of heart weight,
- 225 ml/min
- 4 to 5 percent of the total cardiac output
59
What of the heart is the most important physiological mechanism regulating coronary vascular resistance
Metabolic activity
60
what mechanisms are responsible for metabolic control of the heart?
Nitric oxide
Adenosine
Prostaglandins
K+ATP channels
(causes increased blood flow and vasodilation)
61
Definition: conduction velocity
Dromotropy
62
What is the Baroreceptor Reflex? Where are the receptors for this reflex located?
- Reflex responsible for rapid changes in BP
| - Carotid sinus (and aortic arch)
63
How does the Baroreceptor Reflex help with blood pressure regulation?
Increases or decreases:
- HR
- Contractility
- SVR
64
What is the Bainbridge Reflex? Where are the receptors for this reflex located?
Low pressure sensors that respond to STRETCH - located in pulmonary vein and vena cava
Ex: fluid bolus given to dog increases heart rate
65
In addition to receptor activation what also contributes to the heart rate changes seen with the Bainbridge Reflex?
Stretch of heart and Stretch of SA node
Baroreceptor reflex often change heart rate in opposite direction of baseline (slow to fast, or fast to slow)
66
The ________ Reflex responds to changes in arterial blood pressure
Baroreceptor
67
The ________ Reflex responds to changes in blood volume.
Bainbridge
68
Strong contraction of an under-filled ventricle elicits the reflex, plays a role in blood pressure regulation, results in decreased BP and decreased HR
Bezold-Jarisch Reflex
| could lead to vasovagal syncope or cardiac arrest during spinal
69
Result of decreased blood flow to vasomotor center in medulla:
-increases local concentration of CO2 results in SNS stimulation in medulla, which increases BP
CNS ischemic response
70
What is Cushing's Triad?
- Increase ICP
- Increase HTN
- Bradycardia
71
What is the Diving Reflex? Where are the receptors for this reflex located?
- Cold water on face activates thermoreceptors, decreases HR and peripheral vasoconstriction causes reduced O2 consumption by the body and myocardium
- Facial thermoreceptors
72
What are the differences between the innervation of the heart by the parasympathetic and sympathetic nervous systems?
Parasympathetic:
- negative effects on chrono/ino/dromotroy, resistance vessels
- zero effect on capacitance vessels
Sympathetic:
- Positive effects on chrono/ino/dromotropy, and resistance and capacitance vessels
73
Blood vessels (except for capillaries) have predominantly sympathetic or parasympathetic nervous system innervation?
Sympathetic (norepi via Alpha 1 receptors)
74
relaxation - active, not passive process
lusitropy.
75
Left atrial tract of the electrical system, and also known as...
anterior interatrial myocardial band
Bachmann's Bundle
76
What are the 3 waves seen in a normal CVP tracing?
- a - right atrial contraction (correlates with p wave)
- c - tricuspid valve/ventricular contraction (end of QRS)
- v - blood filling R atrium (end of T wave)
77
What is the formula for calculating Systemic Vascular Resistance?
(MAP - CVP)/CO x 80
78
What is the formula for calculating Pulmonary Vascular Resistance?
(MPAP - PCWP)/CO x 80
79
What formula could you use to predict laminar versus turbulent flow?
Reynold number
| Density, Diameter, Viscosity, Velocity
80
what percent of ECF is interstitial fluid? and plasma?
80%
| 20%
81
What ion makes the major contribution to the resting membrane potential of the cardiac muscle cell?
K+
82
How does the Na+, K+ -ATPase pump contribute to resting membrane potential?
The pump is powered by ATP and moves 3 Na ions out of the cell, and 2 K ions into the cell
83
What ion mines rapidly into a cell during depolarization?
Sodium
84
What ion exits the cell to restore the baseline electrical charge in a cell during repolarization?
Potassium
85
In what part fo the heart are fast-response action potentials (non-pacemaker action potentials) found?
- atrial myocardial fibers
- ventricular myocardial fibers
- purkinje fibers
86
In what part of the heart are slow-response action potentials (pacemaker action potentials) typically found?
- sinoatrial node
| - atrioventricular node
87
What are some differences between non-pacemaker and pacemaker action potentials?
There is no phase 1 in slow response action potential
| -they also start at a higher voltage: -60 or -70, rather than -90
88
What makes the potassium move intra-cellular to extra-cellular
Concentration gradient
89
The membrane potential that is necessary to oppose the outward movement of K+ down its concentration gradient
equilibrium potential
90
It’s determined by the concentrations of positively and negatively charged ions across the cell membrane, the relative permeability of the cell membrane to those ions, and the ionic pumps that transport ions across the cell membrane
resting membrane potential
91
What is depolarization?
When a cell becomes less negative
92
What is repolarization?
When a cell becomes more negative
93
What are the 5 phases of the non-pacemaker (fast-response) action potential?
- Phase 0: depolarization
- Phase 1: partial repolarization
- Phase 2: plateau
- Phase 3: repolarization
- Phase 4: resting membrane potential
94
What is phase 0 of fast response action potential?
Sodium channels open, and rapid inward movement of Na+ causes the cell to rapidly depolarize.
95
What is phase 1 of fast-response action potential?
- inactivation of Na+ channels
- beginning of outward movement of K+ bc too positive inside the cell
- initial repolarization
96
What is phase 2 of fast-response action potential?
- plateau phase
- the slow inward movement of Ca++ counterbalances the outward K+ current
- this delays repolarization and prolongs the absolute refractory period
- the long plateau produces a long action potential to ensure a forceful contraction of substantial duration
97
What happens with calcium-induced calcium release?
The small amount of Ca++ that enters the cells when depolarizer is small, but this triggers the release of a large amount of Ca++ into the cytosol from the sarcoplasmic reticulum with results in binding of myosin to actin and contraction of the myocyte
*calcium increases contractility
98
What is phase 3 of fast-response action potential?
- continued outward current of K+ is responsible for repolarization
- Na+ channel recovery period begins during relative refractory period
99
The period shortly after the firing of a nerve fiber when partial repolarization has occurrred and a greater than normal stimulus can stimulate a second response
relative refractory period
100
The period immediately following the firing of a nerve fiber when it cannot be stimulated no matter how great a stimulus is applied
absolute refractory period
101
What is phase 4 of fast-response action potential?
- back to baseline
- restoration of ionic gradients
- Na+ K+ ATPase pump helps make this happen
102
What is the function of the sarcoplasmic reticulum within a cardiac muscle cell?
Stores Ca++ ions
103
What are the various phases found in pacemaker (slow response) action potentials?
- phase 0
- phase 2
- very brief
- phase 3
- not separated clearly from phase 2
- phase 4
104
What is phase 0 of slow response action potential?
Depolarization mainly by influx of Ca++
105
The ability of a focal area of the heart to generate pace making stimuli
automaticity
106
What pacemaker region of the heart is typically dominant?
SA node
107
This mechanism causes the secondary pacemaker to become hyperpolarized when driven at a rate above it’s intrinsic rate?
overdrive suppression
108
What are the intrinsic rates of the various pacer areas of the heart?
SA node: 60-100
Atrial Foci: 60-80
Junctional Foci: 40-60
Ventricular Foci: 20-40
109
The process by which an influx of CA++ from the interstitial fluid during action potential triggers the release of calcium by the sarcoplasmic reticulum initiating the mechanism of muscle contraction
- Ca++ binds to Troponin-C
- myosin head bind to active
- requires ATP
- reduces sarcomere length
- muscle contracts
excitation-contraction coupling
110
What is the process called whereby large amounts of calcium are released from the sarcoplasmic reticulum?
Calcium-induced calcium release (CICR)
111
What is measured on the y (vertical) axis of eh pressure-volume loop?
Pressure
112
What is measured on the x (horizontal) axis of the pressure-volume loop?
Volume
113
How is time factored into a pressure volume loop?
Not based on time
1 loop = 1 cardiac cycle
114
Which direction does the pressure-volume loop move in during the cardiac cycle?
Counter clockwise
115
How are changes in stroke volume demonstrated on a pressure-volume loop?
Changes in stroke volume will alter the width (left to right) of the loop. The greater the stroke volume, the wider it will be.
116
A change in slope of the end-systolic pressure-volume relationship line indicates a change in what?
Can relate to diastolic heart failure
117
go look at pressure volume loops
.
118
What are the 2 types of acetylcholine receptors?
Muscarinic (only parasympathetic)
Nicotinic (both Para and sympathetic)
119
LaPlace’s Law:
Wall stress = Pr/h
• P = ventricular pressure
• R = ventricular radius
• h = wall thickness
120
What law explains why capillaries can withstand high intravascular pressures?
LaPlaces law
121
__________ Relationship is the predominant factor in matching ________ and cardiac output
Frank-Starling
venous return
122
Determinants of Cardiac Output
Heart Rate
Preload
afterload
contractility
123
An increase in heart rate will also cause positive inotropy, called what?
Bowditch (Treppe) Effect
or “staircase” phenomenon
124
SV =
EDV – ESV
125
what negatively effects stroke volume?
afterload
126
Reynolds number for laminar flow?
<2000
127
Hydraulic filtering composed of what and converts what?
- Composed of elastic conduits (aorta and arteries) and high-resistance terminals (arterioles)
- converts the intermittent output of the heart to a steady flow in the capillaries
128
What are the compensatory mechanisms that are active in hemorrhagic shock?
- Baroreceptor reflexes
- chemoreceptor reflexes
- cerebral ischemic response
- reabsorption of tissue fluids*
- endogenous vasoconstrictor substances
- renal salt and water conservation
129
In shock where is vasoconstriction most prominent?
- Cutaneous vascular bed (cool skin)
- skeletal muscle vascular bed
- splanchnic vascular bed
130
What are the decompensatory mechanisms that occur in progressive shock?
- Cardiac depression
- vasomotor failure
- acidosis
- blood clotting abnormalities
- reticulo-endothelial system
- CNS depression
- Cellular deterioration
- reduced organ perfusion from stimulation of inflammatory process, clotting
131
What are the positive feedback decompensatory mechanisms that are triggered by severe hypotension?
- decreased CO
- decreased Arterial pressure
- decreased O2 blood flow
- tissue hypoxia
- vasodilation
- decreased coronary perfusion
- decreased inotropy
132
Stage of shock in which the normal circulatory compensatory mechanisms eventually cause full recovery without help from outside therapy.
A nonprogressive stage (sometimes called the compensated stage
133
Stage of shock in which, without therapy, the shock becomes steadily worse until death occurs.
A progressive stage
134
Stage of shock in which the shock has progressed to such an extent that all forms of known therapy are inadequate to save the person’s life even though, for the moment, the person is still alive.
irreversible stage
135
Which heart issues have systolic murmurs?
Aortic stenosis
Mitral Regurg
136
symptoms of Aortic Stenosis?
Angina
Syncope
CHF
137
hemodynamic goals of Aortic Stenosis
↑ Preload / ↑ SVR / maintain HR
- increased preload (to fill noncompliant LV - give 500cc NS)
- maintain HR
- increase SVR - Avoid hypotension. (prone to ischemia)
138
Which heart issues have Diastolic murmurs?
Mitral Stenosis
Aortic Regurg
139
Aortic regurg hemodynamic goals?
↑ Preload / ↑ HR / ↓ SVR
140
symptoms of Aortic Regurg?
- eccentric hypertrophy (from volume overload)
- CHF
- Angina
141
symptoms of mitral stenosis?
- CHF (50%)
| - Atrial fibrillation
142
Mitral stenosis hemodynamic goals?
↑ Preload
↓ HR (Slow to allow time for ventricular filling)
↓ PVR (Avoid acidosis, hypercarbia, and/or hypoxemia)
143
Hemodynamic goals of mitral regurg?
↑ HR
↑ Inotropy
↓ SVR
144
symptoms of mitral regurg?
Pulmonary edema
145
hemodynamic goals of hypertrophic cardiomyopathy
↑ Preload
↑ SVR
↓ HR
↓ Inotropy
146
what is associated with aortic valve closure?
- dicrotic notch on ALine
| - second heart sound
147
Contributes to resting membrane potential? (3)
- Potassium diffusion (major Determanant)
- small sodium diffusion
- NaK.ATP-ase pump
148
The characteristics of the upstroke of the action potential depend almost entirely on inward movement of Na+ in what phase and speed action potential?
Phase 0 of Fast response action potential
149
Outward ___ current is mainly responsible for repolarization in fast response action potential
K+
150
What produces the plateau in fast response action potential
Slow inward Ca++ currents
151
s1 closure of?
Tricuspid and Mitral
152
Cardiac Cycle:
```
Ventricular Systole
– Phase 2
• Isovolumic contraction
– Phase 3
• Rapid ejection (70% of ventricular volume is ejected)
– Phase 4
• Reduced ejection
Ventricular Diastole
– Phase 5
• Isovolumic relaxation
– Phase 6
• Rapid filling
– Phase 7
• Diastasis
– Phase 1
• Atrial systole
```
153
What increases afterload?
* Increased aortic pressure
* Increased systemic vascular resistance
* Aortic valve stenosis
* Ventricular dilation
154
Body fluid compartments (percent of total body weight)
ICF: 40%
interstitial: 15%
Plasma: 4%
155
Chemoreceptor Reflex =
- high pCO2, low pO2, & high H+
| - can cause sympathetic response
