Cardiovascular System Physiology Flashcards
(285 cards)
1
Q
The cardiovascular system (CVS) is important in the transport of:
A
- oxygen
- nutrients
- hormones
(to and away from cells, to peripheral tissues)
2
Q
The cardiovascular system is important in the removal of:
A
- cellular metabolic products (Removal of cellular metabolic products (blood vessels, lymph vessels, and blood)
3
Q
What 4 parts makes up the distribution system of the cardiovascular system?
distribution = how blood gets there
A
- Heart
- Aorta + its branches
- Smaller arteries
- Arterioles
4
Q
What 2 parts of the cardiovascular system are involved in dstribution/perfusion?
A
- Arterioles
- Capillaries
supply metabolites to the tissues
5
Q
What 4 parts of the cardiovascular system (CVS) are involved in collecting?
A
- Venules
- Large veins
- Vena cava
- Heart
6
Q
The cardiovacular system maintains equilibrium by the synchronization of what 5 factors?
A
- hydrostatic pressure
- osmotic pressure
- flow
- vessel diameter
- functional tissue systems
7
Q
What is the volume gradient between blood vessels (large and small) and pressure?
A
- large BV; high pressure
- small BV; low pressure)
8
Q
What 2 veins in the body carry oxygenated blood?
A
- Pulmonary vein
- umbilical vein
9
Q
Which artery carries deoxygenated blood?
A
Pulmonary artery
10
Q
slide 10
A
11
Q
Resistance is directly proportional to ____ and inversely proportional to ______.
A
direct- pressure; inverse- flow
12
Q
What is the resistance component of the CVS?
A
The arterial system
13
Q
What is the capacitance component of the CVS?
A
The venous system
14
Q
Capacitance is directly proportional to _____ and inversely proportional to ______.
A
direct- volume; inverse- pressure
15
Q
What are the 3 types of muscles in the heart?
A
- Atrial muscles
- Ventricular muscle
- Specialized excitatory and conductive muscle fibers
16
Q
Why is cardiac muscle structurally unique?
A
- Discs of intercalation
- Syncytium of fibers (multi-nucleated cells)
17
Q
What are the 4 properties of the heart muscle?
A
- Spontaneous rhythmicity.
- Pacemaker or sino-atrial node or S.A. node.
- Action potential is greatly prolonged.
- Contractile force is directly proportional to the degree of stretching.
18
Q
What is known as the pace marker in the heart?
A
Sinoatrial node
19
Q
Where are impulses generated for the heart?
4 factors
A
- SA node
- AV bundle
- Right and left bundles of His.
- Purkinje system or Purkinje fibers
20
Q
Where is there free entry of Na and Ca for fast depolarization?
A
in the Sa node
21
Q
What is the ventral portion of the heart called?
A
apex
22
Q
What is the dorsal portion of the heart called?
A
base
23
Q
What are the 3 components of the right side of the heart?
A
-right atrium
-right ventricle
-right AV valve
24
Q
What are the 3 components of the left side of the heart?
A
-left atrium
-left ventricle
-left AV valve
25
What is the septum?
It divides the heart into right and left halves
26
What vessels bring blood from the upper part of the body and lower part of the body to the heart?
Upper: Superior vena cava
Lower: Inferior vena cava
27
What is the pulmonary artery?
The vessel that brings deoxygenated blood from the **right ventricle** to the **lungs** for oxygen.
*(only time arterial system carries deoxygenated blood)*
28
What is the pulmonary vein?
The vessel that brings **oxygenated blood** back into the **left atrium** of the heart.
*(only time the vein carries oxygenated blood)*
29
What is the aorta?
the large vessel from the **left ventricle** that **takes oxygenated blood** to the rest of the body
30
What 2 structures attach the valves to the walls of the heart?
papillary muscles and chordae tendinae
31
What are the 2 main physiologic functions of the cardiovascular system?
-transport (carrying oxygen, nutrients and hormones to the peripheral tissues)
-removal of waste (cellular metabolic products from blood, blood vessels, and lymph)
32
The extent of blood supply to any organ is dependent on the blood supply to the ______.
heart
33
What are 3 the major divisions of the cardiovascular system?
1. distribution system
2. distribution/perfusion
3. collection system
34
What is the primary function of the heart?
To drive bloodflow throught the body through spontaneous and rhythmic contractile forces
35
What are the 3 factors that effect blood pressure?
- diameter of vessels
- pressure of blood flow
- pumping pressure of the heart
36
How is the diameter of vessels controlled?
| which nervous system contols it?
autonomic nervous system
37
What is the color of oxygenated blood vs deoxygenated blood?
oxygenated: bright red
deoxygenated: dark red
| this is why the blood in veins is almost black when you get blood drawn
38
What factors of the CVS synchronize to maintain systems in equilibrium?
- hydrostatic pressure
- osmotic pressure
- flow
- vessel diameter
- functional tissue systems
39
where is hydrostatic pressure the highest
in the area of the aorta
40
how does osmotic pressure effect synchrony of the CVS
amount of solutes dissolved in blood determines the direction of flow
41
what supports the flow of blood in the CVS
contractile effort of the heart
42
how does vessel diameter effects flow
smaller size = less volume = higher resistance
larger size = higher volume = lower resistance
43
what are the major orderly components of the CVS
- left side of the heart (resistance component)
- right side of the heart (capacitance component)
44
describe the flow of the vascular system
Large arteries → small arteries → arterioles → capillaries → venules → small veins → large veins
45
what are the major resistance sites of the CVS
precapillary beds
46
what is a portal system
areas where a capillary bed gives rise to a vein that then gives rise to another capillary bed before returning to the heart
47
what are the three areas where portal systems occur
renal, digestive, and hypothalamic sites
48
what must lungs have in order to accomodate the large amount of blood it receives from the heart
large cross-sectional area that makes it into a low pressure system
49
what is preload
the amount of blood incoming into the heart; determined by the expansibility of the low pressure venous system vessels and should be maximal in a normal heart
50
what are the factors that decrease preload
- smaller size of the heart chambers
- less space to acommodate incoming blood from the veins
51
what is eccentric vs concentric hypertrophy
eccentric: volume overload; increased lumen size
concentric: pressure overload; decreased lumen size
52
what is afterload
resistance that the heart encounters to propel blood out of the heart through the ventricles; determined by the high pressure of the arterial system and should be minimal in a normal heart
53
what affects afterload
constriction or blockage to the pulmonary trunk or aorta
54
explain the effect of gravity on the cardiovascular system
gravity has a great effect on the vascular pressure at the level of the heart as determined by the hydrostatic pressure; long-necked animals will have higher blood pressure in order to be able to propel the blood longer distances
55
what should the pressure be in the heart/arteries, veins, and pulmonary circulation
heart/arteries: high pressure
veins: no pressure
pulmonary: low pressure
56
what is the organization of the circulatory system
series circuit in the lungs and parallel circuit everywhere else
57
what is coronary circulation
blood supply to the heart itself
58
What is the SA node
area at the entrance of the vena cave where AP's are generated for the heart; SA nods spontaneously generates AP and conducts it to the atria, there the cardiac conducting system transmits it to the purkinje fibers which transmits it through the walls of the ventricles
59
what are discs of intercalation
points where muscle fibers criss-cross over each other and are connected; cells are held within the discs via gap junctions and desmosomes
60
Intercalated discs allow for:
synchrony of contraction between upper halves and lower halves, called functional syncytium
61
what does it mean that the heart has spontaneous rhythmicity
Does not rely on external stimulus to contract, dependent on special excitation cells called SA nodal cells
62
what makes SA node cells able to be self excitatory
low ion channel activation energy for Na and K; requires only small amounts of energy to open channels that allows for fast depolarization
63
explain the conducting pathway of the cardiac action potential
- impulse is generated in the SA node and travels through the atrial muscles to the AV node
- AV node transmits it to the bundle of His that branches into two to go to each side of the heart within the septum
- travels to the purkinje fibers which are divisions of the bundle of His once it branches into the right and left sides of the heart
64
where does delay occur in the conduction of the cardiac action potential
AV node; if the delay is pronounced it can result in heart block
65
List the part of the conducting system of the heart from fastest to slowest conduction velocity:
purkinje system →
bundle branches →
bundle of His →
atrial myocardium →
ventricular myocardium →
AV node →
SA node
66
describe the action potential of cardiac muscle
- excited membrane does not repolarize immediately, but the potential remains in plateau near the peak of the spike for several milliseconds before repolarization begins
- gives the heart musculature time to recover
67
the plateau phase in the cardiac AP is due to what
entrance of large amounts of Ca which enters slowly
68
what are the 5 characteristic phases of the cardiac AP
0: rapid and relatively large influx of Na ions
1: early repolarization caused by transient outward movement of K ions
2: plateau phase due to decreased entry of Na and large but slow influx of Ca
3: repolarization due to K efflux and return of membrane potential to resting value
4: resting phase in AV muscles prior to the initiation of the next AP
69
what is the significance of the plateau phase
protects the heart from too many frequent and out of phase contractions per minute
70
what is the all or nothing principle of the heart
as long as the heart has received stimulation from the SA node, it will contract; refers to the stimulus as applied to the SA node rather than the muscle cells
71
what is the all or nothing principle determined by
the capacity of the cardiac muscles to respond to the impulses generated from the SA node
72
what is the basis for CPR/electrical stimulation of the heart and how a failing heart responds to increased pressure
staircase effect or treppe
73
what is electrocardiography
Scientific study of the recording of the timing of the wave of electrical events that take place in all the chambers of the heart during one complete cardiac cycle
74
what are the components of the complete cardiac cycle
atrial depolarization, atrial repolarization, ventricular depolarization, ventricular repolarization, pressure/volume changes in the great vessels, production of cardiac sounds; latter of the 2 attributed to wiggers
75
what is the electrocardiograph
the instrument used to evaluate electrocardiography
76
what is the electrocardiogram
the recording generated from the electrocardiograph that reflects the electrical activities of the heart and can be used to interpret its functional capacity
77
what must occur in each compartment of the heart before the blood moves to the next compartment
contraction/AP
78
what is einthovens triangle
Triangular landmark on the chest cavity which reflects the position of the heart and the points at which its electrical activity can be detected; any two points become a dipole
79
which three landmarks on the body are the points of the einthovens triangle
Right arm, left arm, and left leg since the heart is situated more on the left side of the body
80
what are the 3 standard types of leads for cardiac detection
lead 1: left arm to right arm
lead 2: right arm to left leg
lead 3: left leg to left arm
81
describe the connection of lead 1
- left arm: +
- right arm: -
- view of lateral wall of the heart
- measures voltage difference between these 2 areas
82
describe the connection of lead 2
- left leg: +
- right arm: -
- monitors rhythm of heart; P wave very clear
83
describe the connection of lead 3
- left leg: +
- left arm: -
- view of inferior/caudal heart wall
84
what are augmented limb leads
when any 2 points are connected to one electrode or terminal of the voltmeter (-) and the one remaining electrode is connected to the other terminal (+); compares the average of the voltage of 2 limbs with that of the remaining one limb
85
describe the connection of AV-R augmented lead
- voltage from right arm (+) compared with average voltage of other 2 limbs (-); right arm is measured
- looks toward the right atrium/medial portion of the heart
86
describe the connection of AV-L augmented lead
- voltage from left arm (+) compared with average voltage of other 2 limbs (-); left arm is measured
- looks toward the left atrium/lateral portion of the heart
87
describe the connection of AV-L augmented lead
- voltage from left leg (+) compared with average voltage of other 2 limbs (-); left leg is measured
- looks toward the ventricles
88
The sum of the augmented leads gives a:
360-degree view of the heart
89
what does the P wave signify
atrial dpolarization
90
what does the QRS complex signify
ventricular depolarization; very large due to the amount of muscle; atrial repolarization occurring at the same time but is insignificant in terms of force
91
what does the T wave signify
ventricular repolarization
92
what does the U wave signify
vibration of the papillary muscles; may not see this on a standard ECG but can sometimes be noticed due to vibration of the chordae tendineae
93
changes in duration of the intervals of the ECG is indicative of what
disease conditions
94
the Q-T segment of the ECG shows what
entire activity of the ventricles
95
what can be expected if the Q-T segment is prolonged
myocardial infarction, myocarditis, hypocalcemia, and hypothyroidism
96
what can be expected if the Q-T segment is shortened
hypercalcemia
97
what does the P-R interval of the ECG show
entire activity of the atria; duration of conduction of impulse from SA node to the ventricles through the atrial muscles and AV node
98
what can be expected if the P-R interval is prolonged
bradycardia and first degree heart block
99
what can be expected if the P-R interval is shortened
tachycardia
100
what does the S-T interval of the ECG signify
isoelectric period
101
what is the J point
point where the S-T segment starts
102
what does an elevation in the S-T segment imply
anterior and inferior myocardial infarction, left bundle branch block, and acute pericarditis
103
what does an depression in the S-T segment imply
acute myocardial ischemia, posterior myocardial infarction, ventricular hypertrophy, and hypokalemia
104
what does a prolonged S-T segment imply
hypocalcemia
105
what does a shortened S-T segment imply
hypercalcemia
106
What ECG changes would be seen with hypokalemia?
- ST depression
- Flat or inverted T wave
- a U wave
107
What ECG changes would be seen with hyperkalemia?
- Flat P wave
- Prolonged PR interval
- QRS widened
- A tall, peaked T wave
108
what ECG changes will you see with hypocalcemia
prolonged ST wave and prolonged QT interval
109
what ECG changes will you see with hypercalcemia
shortened ST segment and widened T wave
110
what ECG changes will you see with hypomagnesemia
tall T wave and ST depression
111
what ECG changes will you see with hypermagnesemia
prolonged PR interval and QRS widening
112
how can you tell which part of the heart is having a problem with an ECG
compare the QRS wave of each lead
113
the distance between each thick line on the ECG paper is equivalent to what
0.2 seconds; 5 boxes = 1 second
114
what does a negative profile of a wave on ECG mean
current moving away from the axis of the heart
115
what does a positive profile mean on an ECG
current moving towards the axis of the heart
116
what is respiratory sinus arrythmia
- some periodic variation in R-R intervals due to the phase of respiration
- R-R interval decreases during inspiration and increases during expiration
- variability decreases in many clinical conditions such as hypertension, diabetes, panic, and anxiety
117
if the peak of the R wave changes rather than the interval, what does this indicated
disease condition rather than sinus arrhythmia
118
what is the mean electrical axis deviation
shows how each compartment of the heart is handling with current being measured by the ECG; if a certain part of the heart draws more current, that part is thickened (ventricular hypertrophy)
119
describe the quadrants of axis deviation
- ventricles = +
- atria = -
- upper left: indeterminate
- upper right: LAD
- lower left: RAD
- lower right: normal
120
what is the clinical significance of an ECG
helps diagnose cardiac arrhythmias
121
what causes cardiac arrhythmias
- abnormal impulse formation (problem with the SA node)
- abnormal impulse conduction (problem with conducting tissues)
- re-entry/circus (problem with the tissue itself that prevents the current from being conducted
122
how does abnormal impulse formation occur in the heart
- altered normal automaticity associated with sympathetic stimulation and decreased parasympathetic tone
- triggered activity
- increased after depolarization
123
what are the receptors associated with increased sympathetic stimulation of the heart
epinephrine on beta 1 adrenergic receptors
ACh on M3 muscarinic receptors
124
what is triggered activity
interruupted cardiac repolarization by another depolarization which can be early or delayed
125
how does after depolarization cause abnormal pulse formation
activates Na and Ca channels causing action potential and triggered response
126
explain the degrees of conduction blocks
- first: no block
- second: intermittent block
- third: persistent or complete block
127
conduction blocks can be _______________ or _________________
unidirectional (antegrade) or bidirectional (retrograde)
128
What are problems with re-entry/circus associated with
delayed depolarization/after depolarization
129
what are the clinical implications of cardiac arrhythmias
- chronic atrial fibrillation
- frequent dizziness after running
- hyperexcitatioin
- wrong drug prescription or effect of newly manufactured drug
- addison's disease (excessive K retention)
130
explain how Addison's disease can lead to cardiac arrhythmias
Aldosterone is not made in sufficient amounts → Na not reabsorbed → K not excreted and therefore builds up in the body
131
describe the innervation of the heart
- innervated by the parasympathetic and sympathetic nervous system
- parasympathetic: indirect innervation
- sympathetic: direct innervation
132
what is the main nerve innervating the heart
the vagus nerve (CN X) of the parasympathetic system
133
where do the sympathetic and parasympathetic fibers of the heart eminate from
sympathetic: lateral medulla; epinephrine from adrenergic receptors
parasympathetic: medial medulla; ACh from cholinergic receptors
134
how do parasympathetic fibers indirectly innervate the heart
acts on sympathetic nerves rather than directly on the heart; acts very sparingly
135
the atria are extensively innervated by which three types of fibers
noradrenergic, cholinergic, and afferent fibers
136
describes the rich innervation of the SA and AV nodes
SA: receives fibers primarily from the right side of the body
AV: receives fibers from both sides of the body
137
Ventricular innervation, with the exception of the bundle of His, is much ___________ profuse than atrial innervation (in mammals but not birds)
less
138
most species have only moderate cholinergic innervation with the exception of what
diving mammals because they can lower their heart rates due to diving reflex
139
The ventricular myocardium receives its modest innervation from where
the coronary plexuses that follow the coronary arteries
140
ventricular innervations are predominantly ____________________
noradrenergic fibers
141
generally, the PSNS fibers to the heart are ______________ and the SNS fibers to the heart are _______________
PSNS: cardiac-inhibitory
SNS: cardiac-excitatory
142
what is chronotropy
heart rate
143
what is ionotropy
effects (contractile strength, rate of pressure, development, and ejection velocity)
144
what is bathmotropy
influence on excitability; opening and closing of ion channels
digitalis/digoxin
145
what is dromotropy
velocity of conduction
146
vagal effect of the heart is mediated by what
ACh
147
what is heart rate
number of heart beats per minute
148
what is bradycardia
decrease in heart rate
149
what is tachycardia
increase in heart rate
150
what is flutter
lower range of tachycardia
151
what is fibrillation
higher range of tachycardia; atrial in most cases, several R-S complexes in a short time with low diastolic volume
152
what is ventricular systole
period of ventricular contraction; blood ejected from the ventricles during this period
153
what is ventricular diastole
period during which the ventricles relax and refill with blood
154
what is end diastolic volume
quantity of blood remaining after ventricular systole and that following ventricular refilling (diastole); determinant of ventricular function and what volume of blood will be pumped out of the heart
155
what is ventricular preload
pressure within the ventricles during diastolic filling
156
what is isovolumetric contraction
contraction of the ventricles when both AV and pulmonary/aortic valves are closed; important in the development of high intraventricular pressure required to push blood into the aorta
157
what is stroke volume
amount of blood pushed into the aorta or pulmonary artery; also called systolic discharge or pulse volume
EDV-ESV
158
what is cardiac output
output of each ventricle per minute; also called minute volume of circulation
SV x HR
159
what is end systolic volume
volume of blood remaining in the ventricles after ventricular systole or period of ventricular ejection
160
what is ejection fraction
functional capacity of the ventricle; fraction of end diastolic volume that is ejected during ventricular systole
SV / EDV
161
what is a high ejection fraction indicative of
high functional efficiency of the heart
162
what 3 things affect heart rate
body size, metabolic rate, and autonomic characteristics of the species
163
What is the equation for HR?
| ??? check
HR = 241 x BW^-0.25
164
more athletic animals have _____________ vagal tone and ___________ resting heart rates than do sedentary species of similar size
higher, lower
165
what are the 4 main methods for determining cardiac output
1. flick procedure
2. echocardiography
3. indicator dilution method
4. implantation of an electromagnetic flow meter in one of the major arteries leaving the heart
166
describe flick procedure
reciprocal of how much oxygen the tissue has consumed and the difference between oxygen in arterial system and venous system; substance consumed is a product of cardiac output and AV difference
167
what organ does the flick procedure use for measurement
lungs
168
what is the pericardium
thin membrane that covers the heart and holds pericardial fluid
169
what is pericarditis
inflammation of the pericardium; common in ruminants
170
what are the functions of the pericardium
- protects the heart against over-dilation
- provides smooth surfaces for the heart's physical action
- holds the heart in a relatively fixed position
- assists in relaxation of the heart by exerting a suction force
171
what are the steps of the cardiac cycle in order
- early atrial diastole
- late diastole/diastasis
- atrial systole
isovolumetric contraction
- early ventricular systole
- late ventricular systole
- early diastole
- isovolumetric ventricular relaxation
172
what % of blood goes from the atrium to ventricle passively vs actively via systole
70% passive
30% active
173
when does the first heart sound occur
isovolumetric contraction due to closure of the AV valves
174
at the end of isovolumetric contraction, pressure in the ventricles is ?
high
175
maximal ejection of blood occurs during what phase
early ventricular systole
176
when does the second heart sound occur
during early diastole when the semilunar valves close due to retrograde flow of blood in the aorta
177
what are the two major changes during the cardiac cycle
pressure and volume
178
what is the vasomotor center for regulation of cardiac activity
medulla
179
what is starlings law
Heart can readjust itself and its contractile strength to accommodate the amount of blood that has been returned to the heart; elasticity is directly proportional to the contractile force
180
what are the two heart sounds and what are they associated with
S1: systolic sound "lub"
- closure of AV valves
- usually more intense than S2
- in horses, S2 more intense than S1
S2: diastolic sound "dub"
- closure of the semilunar valves
181
what is cardiac auscultation
perception of audible vibrations produced by the heart as sounds when the ear or stethoscope is placed at the appropriate locations
182
what is ventricular gallop/protodiastolic gallop
transient sound that is rarely heard along with S2 due to rapid filling of the ventricles
183
what is a phenocardiogram
a graphic recording of the heart sounds after they have been transduced to an electrical signal with a microphone
184
what are the third and fourth heart sounds
S3: occurs during the first half of diastole, during passive ventricular filling (between T wave and the ensuing P wave (70%)
S4: occurs late in diastole after atrial activation (P-wave) and contraction (30%)
185
in what species is a third heart sound normal
horses
186
what is ectopic pacemaker/ectopic foci
Portions other than the SA node and AV node assume pace making function by spontaneously responding to threshold before the regular SA node or even the AV node pacemaker
187
what are some causes of ectopic pacemaker/ectopic foci
hypoxia, ischemia, infections, ventricular fibrillation
188
what is ventricular escape reading
ventricles assume pacemaker function; results in poor circulation and significant disruption of cardiac pattern
189
describe heart failure
- Described as any condition in which a depressed cardiac contractility limits the ability of the heart to deliver a normal cardiac output
- Leads to various life threatening conditions which if not reversed culminates to death
190
what is ventricular escape
- Effect of parasympathetic stimulation yielding a decrease or stoppage of SA node rhythmicity and ventricular excitability
- Development of rhythm along purkinje fiber
- results in inefficient activity of the heart
191
what are some conditions that. can lead to decreased heart rate
- Reduced speed of impulse transmission along conduction pathway
- small junction connections at discs of intercalation due to infection, neoplasia, necrosis, etc.
- embryonic type cells even at the adult stage of the animal
192
what are murmurs
Prolonged extra or abnormal heart sounds generally produced at or near a valvular orifice due to structural changes to the valves or turbulence in the blood flowing through the narrow valvular opening
193
what are the two classifications of murmurs
systolic and diastolic
194
describe a systolic murmur
result as blood regurgitates through incompetent AV valves or as blood is ejected through the semilunar valves; can be due to incompetency (valve not well closed), mitral or tricuspid regurg, aortic/pulmonary stenosis, or ventricular septal defect
195
describe a diastolic murmur
heard during diastole; usually heard at the commencement of or after second heart sound and terminate before or at first heart sound; due to aortic/pulmonary regurg, AV regurg, or vegetative endocarditis
196
what is the difference between an early, mid, and late diastolic murmur
early: same time as S2
mid: after S2 but before S1
late: after S2 and extends up to S1
197
what is aortic valve stenosis and what does it lead to
narrowing and inefficient opening of the aortic valve that leads to ventricular hypertrophy
198
what is fetal circulation characterized by
mixing of the blood from the left and right sides of the heart
199
about half of the total volume of fetal blood goes where
to the placenta via the umbilical arteries
200
from the placenta where does fetal blood flow
- some flows to the fetal liver through umbilical veins
- well-oxygenated blood returning to the heart from the placenta via the umbilical vein via ductus venosus shunt between the umbilical vein and caudal vena cava
201
blood from the pulmonary artery gets to the aorta by what
ductus arteriosus
202
fetal blood can flow from the right atrium to the left atrium via what
foramen ovale
203
what is prostaglandin E1
vasodilator responsible for keeping the shunts of the fetal heart open until birth; can result in a hole in the heart if prostaglandin is not inhibited prior to birth
204
which is the most common shunt to remain open in the case of "hole in the heart" and how is it treated
ductus arteriosus; treated with indomethacin: a prostaglandin inhibitor
205
what provides supply to the upper body in fetal circulation
brachiocephalic and cranial subclavian artery branches of aorta
206
what provides supply to the lower body in fetal circulation
caudal subclavian artery branch of the aorta
207
what is the function of the ductus arteriosus
- protects lungs against circulatory overload
- allows right ventricle to strengthen
- maintains high pulmonary vascular resistance and low pulmonary blood flow
- carries mostly mild oxygen-saturated blood
208
what is the function of the ductus venosus
- connects umbilical vein with caudal vena cava
- good sphincter that regulates fetal blood flow
- carries mostly oxygenated blood
209
What is the function of the foramen ovale?
shunts highly oxygenated blood from the right atrium to the left atrium
210
what are the major post-natal circulatory changes that occur
- expansion of lungs
- reduction in pulmonary vascular resistance
- drop in pulmonary arterial pressure
- increase in systemic arterial pressure
- increase in pulmonary blood flow
- rise in left atrial pressure above right atrial pressure
- closure of foramen ovale and ductus arteriosus
211
the vascular system receives mostly sympathetic supply with the exception of what
blood vessels and external genitalia
212
what are the 2 types of arteries
muscular and elastic
213
what are the characteristics of elastic arteries
- withstand high pressure
- include aorta, some of its large branches, and the pulmonary artery
- damping vessels
- windkessel effect (recoiling effect)
214
what are the characteristics of muscular arteries
- greater % of smooth muscles compared to elastic arteries and other elastic tissues
- act as conduits for the transfer of blood under high pressure to tissues
- innervated by adrenergic and some instances by cholinergic fibers
215
what are the receptors in vessels responsible for vasodilation and vasoconstriction
alpha 1: vasoconstriction
beta: vasodilation
216
what is the major sites of resistance to blood flow
muscular arteries
217
vessels are excited to produce either vasodilator or vasoconstrictor effects
myostretch
218
what are the function of muscular arteries
they aid in the regulation of systemic blood pressure and modulate tissue perfusion pressure
219
what are capillaries
subdivisions of the arterioles which comprise an inter-anastomosing system of vessels devoid of muscular elements; large SA and low flow velocity
220
what is the structure of capillaries
single layer of endothelial cells joined by intercellular matrix of Ca propionate
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what are the types of capillaries based on the arrangement of endothelial cells
- continuous (lung and muscle
- fenestrated (kidney and intestine)
- discontinuous (liver, spleen, and bone marrow)
222
describe the AV shunt
- occurs in areas where blood may need to bypass the tissue at certain times
- goes straight from artery to vein by bypassing the capillary bed
- contain smooth muscle cells throughout their entire length
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what are some locations where you will see an AV shunt
highly vascularized tissue beds (penis, nose, earlobes, snout, liver, spleen, lungs, and skin)
224
what are the characteristics of venules
- slightly thicker walls than capillaries
- very thin wall in relation to their lumen
- more elastic
- sparse innervations compared to arterioles
225
what are the characteristics of veins
- contain 2 layers of smooth muscle which are separated by a layer of CT
- walls much thinner than arteries
- only the outer layer is innervated
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what is hemorrheology
Hemorrheology is the study of blood flow in the vascular system
227
Velocity of blood flow in the arteries and veins is ___________ whereas in the capillaries it is _____________
rapid, slow
228
pulsations are frequently seen in __________, but not usually in ____________
arteries, veins or capillaries
229
what drives blood to flow
pressure difference
230
how do you calculate total peripheral resistance to blood flow
pressure / CO or (MAP-CVP)/CO
MAP: mean arterial pressure
CVP: central venous pressure
231
what is poiseuille's law
R = 8Lη/πr4
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how does resistance relate to vessel length, blood thickness, and flow
long vessel = high resistance
thick blood = high resistance
high resistance = low flow
233
describe the Young-Laplace law of vessel pressure
- general principle for blood flow that describes pressure in fluid
- as pressure drops, radius increases
- P = (2Th)/3R
234
what causes increased vessel thickness/clogged vessels
cholesterolemia
235
describe the Fahraeus-Lindquist effect
refers to the decrease in apparent blood viscosity as the diameter of the vessel decreases; felt in small vessels more than large vessels
236
what is laminar flow
normal flow pattern of blood whereby cells are streamlined and flow normally
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what is shear stress
phenomenon in fluid flow described by the increase in RBCs and its frictional effect on the walls of vessels
238
how does high viscosity impact shear stress
high viscosity = low shear stress
239
when the left ventricle ejects blood into the aorta, the aortic pressure -_______
rises
240
what is systolic pressure
the maximal aortic pressure following ejection
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what is the diastolic pressure
The lowest pressure in the aorta, which occurs just before the ventricle ejects blood into the aorta
242
what are baroreflexes
activate the sympathetic nervous system when there is a decrease in arterial pressure and increases catecholamine release which increases cardiac activity; automatically adjust cardiac function to support changes in arterial pressure
243
chronic decrease in arterial pressure can lead to what
reduced tissue blood perfusion which in turn lead to increased lactate formation due to poor availability of oxygen for aerobic metabolism of glucose
244
a rise in total peripheral resistance in the face of reduced flow accounts for what
the preservation of arterial pressure
245
what factors influence blood pressure
- cardiac output
- total peripheral resistance
- arterial stiffness
- blood pressure varies depending on situation, emotional state, activity, and relative disease/health status
246
how does total peripheral resistance effect blood pressure
if there is a blockage, output will reduce and hypertension will result
247
how does arterial stiffness influence blood pressure
if a vessel is not elastic its diameter cannot change to respond to changes in volume
higher stiffness = higher BP
248
how is blood pressure regulated in the short term
by baroreceptors which act via the brain to influence nervous and endocrine systems
249
what are barorreceptors sensitive to
changes in arterial pressure
250
what is pulse pressure
the difference between the measured systolic and diastolic pressures
Psys - Pdias
251
what is hypertension
excessive increase in BP that is pathological
252
hypertension predisposes what conditions
rupture of fragile vessels and hypertrophy of the heart; puts the heart at risk due to excessive task of overcoming resistance
253
pulmonary hemorrhage common in what species subjected to high exercise
horses; nose bleeding
254
what is hypotension
excessive decrease in BP that is pathological
255
what does hypotension cause in the body
Low oxygen supply to vital organs because pressure is not sufficient enough to propel blood to tissues
256
what is the direct method for measuring BP
auscultatory; essentially block arteries (ventricles) by inflating the cuff and then deflate and listen with stethoscope; first sound after opening cuff (systolic pressure) and first disappearance of that sound (diastolic pressure)
257
what are the sounds called with the auscultatory method
sound of korotkov
258
what are examples of indirect (wearable) methods of measuring BP
- pulse detector
- ultrasound
- radiotelemetry
259
how do you calculate mean arterial pressure
MAP = CO x SVR
SVR: systemic vascular resistance
260
anything that compromises the volume of blood returning to the heart will affect ____________
preload
261
increased afterload causes what issue to occur
hypertension
262
What is the conduction velocity of the SA node
Less than 0.01
263
What is the conduction velocity of the atrial myocardium
1-1.2
264
What is the conduction velocity of the AV. Node
0.02-0.05
265
What is likely happening in the case of a heart block?
Delay of the AV node
266
What has the slowest conduction velocity?
AV node
267
What has the fastest conduction velocity?
Purkinje fibers
268
What is the conduction velocity of the bundle of his
1.2-0.05
269
What is the conduction velocity of the bundle of branches
2-4
270
What is the conduction velocity of the purkinje fibers
2.02-4.03
271
What is the conduction velocity of the ventricular myocardium
0.3-1.0
272
What are the stages of the heart polarization
Resting membrane
Depolarization
Repolarization
273
What is caused by the entrance of large amount of calcium in the membrane potential
Plateau effect in phase 2
274
In cardiac muscle the excited membrane does not repolarize immediately after ...
Depolarization
275
The potential remains on a .... near the peak of the spike sometimes for many milliseconds (actually about 0.2 - 0.3 seconds) before repolarization begins.
Plateau
276
What phase is caused by the rapid and relatively large influx of sodium ions (fast inward current) into the cell
0
277
What phase is the early phase of repolarization is caused by the transient outward movement of the potassium ions
1
278
What is the plateau phase, is attributed to the continued, but decreased, entry of sodium and a large, but slow, influx of calcium ions (slow inward current) into myocardial cells.
2
279
What is the phase of repolarization during which the membrane potential returns to its resting value because of potassium efflux (outward current) from the cell
3
280
What is a resting phase in atrial and ventricular muscle cells prior to the initiation of the next action potential.
4
281
What protects the heart from too many frequent and out of phase contraction (per minute).
Plateau
282
What is hydrostatic pressure?
The pressure that exists within standing or stationary fluids like water
283
In the heart, action potential is greatly ______.
prolonged
284
Contractile force is directly proportional to the ___________.
degree of stretching
285
Autonomic nerves have a ______ function.
antagonistic
