cardiac Flashcards
1
Q
name the two coverings of the heart?
A
pericardium
epicardium
2
Q
name the three functions of the pericardium?
A
protect the heart
anchor the heart to surrounding structures
prevent the heart from over filling with blood
3
Q
describe the epicardium?
A
a thin, slippery membrane that turns inward at the base of the heart and lines the external surface of the heart
4
Q
what is the pericardial space?
A
The space between the pericardium and epicardium that fills with serous fluid allowing the two layers to glide past one another during normal cardiac functions
5
Q
Name the three layers of the heart wall from outer to inner?
A
epicardium (outer)
Myocardium (middle layer of muscle tissue)
Endocardium (inner layer)
6
Q
The endocardium contains a thin layer of ______ _______ that is covered by a thin sheet of __ __ cells that line the chambers and is continuous with blood vessels that enter and leave the heart.
A
connective tissue
squamous epithelial
7
Q
The heart has how many chambers?
A
4
8
Q
How many atria and ventricles?
A
2 atria
2 ventricles
9
Q
Describe the function and structure of the atria?
A
Function: The atria are the receiving chambers for blood returning to the heart from the systemic and pulmonary circulation.
Structure: They are smaller chambers with thin walls that contract generating minimal pressure.
10
Q
Describe the function and structure of the ventricles?
A
Function: Provide the pressure needed to push blood throughout our entire body.
Structure: they make up the bulk of the heart, meaning they have thicker walls b/c they generate a higher pressure
11
Q
describe the structure of the pericardium?
A
The out fibrous layer composed of tough dense connective tissues
12
Q
describe the blood flow through the heart?
A
right atrium-right tricuspid valve-right ventricle-pulmonary valve-pulmonary circulation-left atrium-left bicuspid valve-left ventricle-aortic valve-systemic circulation- then start over back at the right atrium
13
Q
name the three sources of blood supply that empty into the right atrium?
A
superior vena cava (body regions superior to the diaphragm
inferior vena cava (body regions inferior to the diaphragm,
coronary sinus (blood from the heart)
14
Q
What is the goal of the heart valves?
A
to maintain unidirectional blood flow throughout the heart.
15
Q
What are the atrioventricular valves?
A
Valves located between the atria and the ventricles
16
Q
The AV valves prevent what from happening?
A
keep blood from flowing from the ventricles into the atria, while the ventricles are contracting
17
Q
The left AV valve is called the ?
A
bicuspid valve
18
Q
the bicuspid valve has how many cusps? and is also known as the?
A
2 cusp
Mitral Valve
19
Q
The AV valves are attached to ____ ____ which are attached to _______ muscles.
A
chordae tendineae
papillary muscles
20
Q
what is the purpose for the AV valves being attached to the chordae tendineae?
A
To provide strength and reinforcement to keep the valves closed when pressure builds up within the ventricles.
21
Q
Describe the AV valve position as blood flows from the atria to the ventricles and from the ventricles to the systemic circulation
A
The av valves hang limply when blood is flowing through the atria into the ventricles and closed when the ventricles are contracting.
22
Q
What are the valves located between the ventricles and the large arteries called? and name the two valves?
A
semilunar valves
aortic and pulmonic valve
23
Q
The right semilunar valve is the _______ valve.
A
pulmonic
24
Q
the left semilunar valve is the _____ valve.
A
aortic
25
The semilunar valves are shaped like a?
crescent moon
26
the semilunar valves have how many cusps?
three
27
describe the position o the semilunar valves during ventricular contraction and relaxation?
The semilunar valves are open during ventricular contraction and when the ventricles relax blood flows back from the arteries and fills the cusps at the semilunar valves forcing them closed.
28
How many types of cells are involved in the contraction of the heart? Name them.
2
contractile cells
auto-rhythmic cells
29
The most abundant cell type involved in the contraction of the heart is? they make up about \_\_\_\_% of the heart cells and are primarily involved in contraction
myocardial contraction cells
99%
30
Describe pacemaker or auto-rhythmic cells
These cells are involved in the intrinsic electrical conduction system that is mostly responsible for initiating and conducting the action potential responsible for contraction.
31
does pacemaker or auto-rhythmic cells contract?
no, but they are responsible for allowing the contractile cell to continue to function normally.
32
what are the slow and fast response cells in the heart?
slow: autorhythmic cells
fast: contractile cells
33
describe how cardiac muscle is similar to the skeletal muscle?
it contracts by the sliding filament mechanism, which consists of thin filaments (which are polymers of actin, troponin, and tropomyosin) sliding over stationary thick filaments like myosin, thereby shortening the length of the muscle
34
Cardiac cells are short _____ \_\_\_\_\_ cells with _____ nuclei.
striated branched
one or at most two nuclei
35
Individual cardiac muscle cells are interconnected and held together at their ends by specialized junctions called?
intercalated disc
36
not only are the plasma membranes interlocked, but president intercalated discs are ______ and \_\_\_\_\_\_.
desmosomes and gap junctions
37
describe desmosomes function?
mechanically hold cells together
38
describe gap junctions function?
electrically couple adjacent cells, allowing action potentials to spread from 1 cell to adjacent cells.
39
contractile cells have lots of _______ and use ____ \_\_\_\_ as primary source of energy.
mitochondria
Fatty acids
40
\_\_\_\_\_\_\_\_ from both the extracellular fluid and the sarcoplasmic reticulum , initiate a cascade of events resulting in contraction.
Calcium
41
This coupling of electrical impulse to contraction is called?
excitation contraction coupling
42
Contraction of myocardial contractile cells is triggered by what?
A complete reversal in membrane potential and basically an action potential triggers a set of events that results in myocardial contractions.
43
describe sliding filament theory?
Step 1: Once calcium (key) is bound to troponin-C (lock) and the conformational change of tropomyosin (bike Chain) has occurred allowing myosin (person) being capable to bind to actin (bike)
Step 2: ATP can bind to the myosin head allowing the binding to actin filament.
Step 3: The ATP is hydrolyzed into ADP and inorganic phosphate. Following this ADP and inorganic phosphate are released from the myosin head so the power stroke can occur.
Step 4: In this the myosin head pivots and bends, pulling on the actin and moving it, causing muscle contraction.
Step 5: After this occurs a new molecule of ATP binds to the myosin head, causing it to detach from the actin.
Step 6: Following this, the cycle can begin again and further contraction can occur.
44
name two places calcium comes from in order to cause a cardiac contraction?
extracellular fluid and the sarcoplasmic reticulum
45
The membrane potential of contractile cells remains essentially at about _______ unless there is an input from an outside signal.
-90
46
Contractile cells are stimulate by ____ \_\_\_\_\_ channels that open allowing a influx of ______ ions which depolarize the cell.
fast sodium
sodium
47
The action potential results in a complete reversal of the membrane potential, so it is going from -90 to ____ millivolts
+30
48
The fast sodium channels are only very briefly and are quickly inactivated by the ______ \_\_\_\_\_ \_\_\_\_.
positive membrane potential
49
Once the sodium channels close, what channels open and what happens?
fast potassium channels open, resulting in an efflux of potassium and slight depolarization as the membrane potential becomes slightly less positive.
50
following the fast potassium channels opening, what channels open? and what happens?
the slow L-type calcium channels are then activated and opened. Then calcium enters the cells from the extracellular fluid and the sarcoplasmic reticulum.
51
what prolongs the positive membrane potential inside the cell known as the plateau portion of the action potentials?
The continued influx of calcium
52
Why is the potassium channels slowly closing during the plateau portion of the cardiac contractile cell action potential graph?
preventing rapid repolarization of the membrane potential
53
during the down swing on the graph for cardiac contracticle cells depicting rapid depolarization, what is occuring?
calcium permeability is reduced by inactivation of calcium channels and the potassium channels are activated promoting a record rapid outward diffusion of potassium ions resulting in the repolarization of the cells and the restoration of the resting membrane potential
54
How long is the action potential of a cardiac contractile cell?
250 milliseconds
55
what is the absolute refractory period? what causes this?
The period known as the action potential (250 milliseconds) when a second action potential cannot be triggered until an excitable membrane has recovered from the action potential.
the sodium channels being incapable of opening so shortly after activation.
56
57
the absolute refractory period prevents what?
subsequent rapid contraction and provides enough time for the ventricles to fill with blood between contractions, and prevents tetanic contraction (which is when a muscle stays in contracted state for too long.
58
what is the maximum heart rate is _____ beats per second, _____ beats per minute
4 beats per second
240 beats per minute
59
say the acronym for the cardiac contractile cell's action potential and describe the process
**Summit-** Sodium channels open and allow an influx of sodium ions which depolarizes the cell, resulting in a complete reversal of the membrane potential from -90 to +30. Sodium channels are innactivated by the positive membrane potential
**Plummet -** Fast potassium channels open, resulting in an efflux of potassium and slight repolarization of the membrane potential
**Continue -**Slow L-type **calcium channels** are then activated and **open**, **calcium enters the cells** from the **extracellular fluid** and the **sarcoplasmic reticulum**. The continued influx of the calcium prolongs the positive membrane potential. Potassium channals slowly closing.
**Plummet -** Calcium channels are closed and **potassium channels open** wide and promote a **rapid outward diffusion** of **potassium ions** resulting in repolarization of the cells and **restoration of the resting membrane potential**.
60
\_\_\_\_\_ enters the cytoplasm of the cell and binds to the troponin-tropomyosin complex that resides in active polymer of the thin filaments.
which allows ______ to form cross bridges
Calcium
myosin
61
62
During the plateau phase of the cardiac contractile cell's membrane potential, when cytosolic ______ levels are high and a contraction occurs for the same amount of time the levels are high in the cell.
calcium
63
when calcium channels open after the efflux of potassium following the initation of the action potential, the influx of extracellular calcium triggers what? this process is called what?
the opening of a special subset of calcium channels in the membrane of the sarcoplasmic reticulum.
calcium induced calcium release
64
Calcium induced Calcium Released ensures what?
a dramatic increase in cytosolic calcium sufficient to stimulate contraction. Higher levels of calcium stimulates a stronger contraction.
65
Cardiac autorhythmic cells are also known as?
pacemaker cells
66
Cardiac autorhythmic cells have an unstable resting membrane potential that leads to _____ \_\_\_\_\_ \_\_\_\_\_\_.
spontaneous action potentials
67
Describe the Cardiac Autorhythmic Cells Action Potential Cycle
1. Pacemaker potential - The membrane potential slowly depolarizes (less negative than the resting potential), caused by a slow leak of sodium through voltage gated sodium channels, allowing sodium ions to enter the cell. The potassium channels are closed reducing the efflux of calcium. The potassium piling up in the cell and sodium coming into the cell increases the positive membrane potential until it reaches threshold.
2. Once the depolarization reaches a critical level known as threshold (which occurs at -55 to -50mV), and explosive depolarization or action potential can take place. Meaning the action potential spreads throughout the heart, triggering the myocardial contractile cells to contract. This occurs, because at threshold voltage gated calcium channels (L-Type Calcium channels ) open allowing the influx of calcium producing the exposive positive membrane potential.
3. Once the positive membrane potential of 0 mV is reached the calcium channels close and the potassium channels open, and potassium flows out of the celll causing the membrane potential to repolarize.
4. Once repolarization has occured (-60 mV) potassium channels clos and depolarization to threshold begins again.
68
action potential for the pacemaker cells is from what mV to what mV?
-55/-50 to 0
69
what type of calcium channels open during the pacemaker action potential?
L-type Calcium channels, L for long lasting
70
what is the mV threshold for pacemaker cells?
-55 to -50
71
what is the range for slow depolarization for pacemaker cells?
-60 to -55/-50
72
The pacemaker cells of the heart are located at specialized sites in the heart, which are?
SA node
AV node
AV bundle
Right and Left Bundle branches
Purkinjie fibers
73
where are the purkinje fibers located?
in the ventricular walls
74
depolarization waves spread from one pacemaker cells to another via ____ \_\_\_\_\_\_ through a specialized conduction system.
gap junctions
75
The depolarization of the heart from pacemaker cells follows what route through the heart?
SA node-AV node-Bundle of HIS- Right and Left Bundle Branches- purkinje fibers
76
the SA nodes typically generates ____ depolarizations or heart beats per minute ____ to \_\_\_\_.
75 depolarizations
60-100 beats per minute
77
The sinoatrial node is a ____ shaped region. Located where?
crescent shaped region
right atria wall near opening of SVC
78
The SA node set of cells act as the pacemaker cells because why?
Because they generate the highest frequency of impulses
79
From the SA node the depolarization moves through the atria to the _____ \_\_\_\_\_\_.
AV node
80
The AV node is a small bundle of cells located at the base of the _____ \_\_\_\_\_ near the septum above the _____ \_\_\_\_\_.
right artium
tricuspid valve
81
There is less than ____ second delay at the AV node. Why?
0.1 second
Allowing atria to complete their contraction before the impulse travels into the ventricles.
82
The 0.1 second delay at the AV node occurs due to what?
fewer gap junctions in this section of tissue, slowing the conduction
83
The impulse spreads from the AV node to the?
Bundle of HIS (AV Bundle)
84
The AV bundle is located in the upper ______ \_\_\_\_\_\_\_.
intraventricular septum
85
The AV Bundle separates into the right and left _____ \_\_\_\_\_ and travels down the septum toward the apex.
bundle branches
86
The right and left bundle branches lead into the _____ \_\_\_\_\_ at the apex.
purkinje fibers
87
The purkinje fibers project into the _______ \_\_\_\_\_\_\_\_ like twigs of a small branch
ventricular myocardium
88
In a normal heart the total time between the firing of the SA node and ventricular depolarization is how many milliseconds?
220 mS
89
The AV node depolarizes how many times per minute?
50 times per minute
90
AV Bundle and Purkinje Fibers depolarized how many times per minute?
30 times per minute
91
The AV Node, AV Bundle and Purkinje Fibers are back up systems meaning what?
meaning they will maintain the heart rate in the event that the faster pacemaker become dysfunctional.
92
Ventricular contraction occurs how soon after depolarization?
almost immediately
93
Because depolarizaiton moves down the intraventricular septum then to the apex then moves along free ventricular walls toward the atria, this causes the heart to contract from the _____ to the \_\_\_\_\_, meaning blood is ejected superiorly into what?
apex to the base
large arteries leaving the ventricles
94
The cardiac cycle begins and ends with what phase?
ventricular diastole
95
Blood flow through the heart is controlled by ____ \_\_\_\_\_ and blood flows down a pressure gradient through any available opening.
pressure changes
96
The pressure changes in the cardiac cycle reflect the alternating ______ and _____ of the myocardium and direct heart valves to open or close, which maintains what?
contraction and relaxation
the unidirectional blood flow through the heart.
97
The term systole and diastole refer to the activity of the \_\_\_\_\_\_.
ventricles
98
How many phases in the cardiac cycle?
three
99
Phase one of the cardiac cycle is what?
ventricular filling which is mid to late diastole for the ventricles, and involves the atria contracting.
100
during phase 1 the aortic and pumonary valves are \_\_\_\_\_\_.
closed
101
during ealy ventricular diastole (phase 3) what is happening?
the blood is passively flowing from the venous system through the atria and open AV valves into the ventricles. Both the atria and the ventricles are relaxed and the volume in the ventricles is slowly filling
102
during phase three (early diastole of the ventricles) how much ventricular filling occurs?
80%
103
In Phase 1 the ventricles continue to fill until the pressure build causing what?
AV Valves to close
104
during the late phase of ventricular diastole (Phase 1) the SA node membrane potential reaches the threshold and what occurs?
fires an action potential atrial depolarization triggers atrial contraction which forces more blood into the ventricles
105
how much blood is pushed into the ventricles witht he atria kick?
20%
106
What is the EDV?
the end diastolic volume, the volume of blood in the ventricle at the end of diastole
107
are the atria contraction in phase 2 or phase 3?
no
108
during what phase is the atria contracting?
phase 1
109
Phase two of the cardiac cycle is known as what?
ventricular systole
110
describe what happens in phase two of the cardiac cycle?
at this point the action potential has spread into the ventricles and they begin contracting, the pressure inside the ventricles rises sharply and rapidly closing the AV valves. The pressure continues to rise and exceeds the semilunar valves causing them to open, and blood is ejected from the ventricles inot the aorta and the pulmonary artery. The ventricles pressure peaks during this phase
111
for an instant in phase 2 of the cardiac cycle knonw are ventricular systole, the ventricles are completely closed chambers which is called?
isovolumetric contraction phase
112
When blood is ejected from the ventricles into the aorta and the pulmonary arteries, this is known as?
Bentricular ejection.
113
ventricular pressure peaks during which phase?
phase II
114
Phase three of the cardiac cycle is known as what?
isovolumetric relaxation phase
115
Describe what happens in phase three of the cardiac cycle?
The ventricles begin to relax and for a brief moment, ventricular pressure drops and blood pressure in the aorta and PA force the semilunar valves closed, creating isovolumetric relaxation b/c the AV valves are still closed as well.
116
What is ESV? describe it?
End systolic Volume, the amount of blood in the ventricles at the end of systole
117
What is Isovolumetric relaxation? It occurs during which phase?
During phase III, when the ventricles relax and blood pressure in the aorta and PA force the semilunar valves closed and the AV valves are still closed.
118
All during ventricular systole the atria have been in _____ and blood has been?
diastole, and blood has been flowing into them and the pressure has been rising.
119
once the pressure in the atria has exceeded the pressure inside the ventricles, what happens?
the AV valves are forced open, beginning ventricular filling again.
120
the length of the cardiac cycle is less than ____ seconds?
1 second
121
what is cardiac output?
the volume of blood pumped by the ventricle per minute
122
The cardiac output of each ventricle must be what?
the same
123
Cardiac output is determine by what?
the heart rate x stroke volume
124
The stroke volume is what?
the volume of blood the heart pumps per beat or per stroke
125
The average heart rate is?
75 bpm
126
the average stroke volume is ?
70 mL/beat
127
The average cardiac output is?
75 bpm x 70 mL/beat = 5.25 L/minute
128
cardiac output can dramatically increase during exercise up to ___ to ____ liters per minute
20 to 25 liters per minute
129
What is the cardiac reserve?
The difference between the cardiac output at rest and the maximum cardiac output
130
The reason the cardiac output can vary dramatically is because?
the heart rate and stroke volume can vary greatly.
131
heart rate is primarily controlled by what?
the pacemaker cells of the SA node
132
The heart rate is innervated by the ____ and \_\_\_\_\_.
SNS and PSNS
both divisions of the ANS innervate the SA and AV nodes
133
PSNS will ____ the heart rate.
decrease
134
What is released by the Vagus nerve fiber?
Acetylcholine
135
The vagus nerve is a part of the _____ nervous system.
parasympathetic
136
Acetylcholine binds to _____ receptors.
muscarinic receptors
137
when acetylcholine binds to muscarinic receptor adn is coupled to ____ \_\_\_\_\_\_, which reduces what?
inhibitory G-Protein Coupled Receptors
reduces adenylate cyclase activity and reduce cAMP production
138
how does acetylcholine slow the heart rate?
by increasing potassium permeability of the pacemaker cells of the SA. and AV node, meaning potassium leaves the cell, making the membrane potential more negative which makes the membrane potential is even further away from the threshold and decreases the rate of spontaneous depolarization.
The time required to drift to threshold is increased which decreases the heart rate.
139
Muscarinic receptor is coupled directly to a _____ channel.
potassium channel
140
SNS will ____ the heart rate.
increase
141
Norepinephrine binds with _____ adrenergic receptors to increase the heart rate.
Beta 1
142
Beta 1 receptor are coupled to a ________ \_\_\_\_\_\_\_.
stimulatory GPCr
143
The Beta 1 receptor coupled w/ a stimulatory GPCr does what?
increases the activity of adenylate cyclase and increase cAMP production in the SA and AV Nodes, as well the pacemaker cells located in the ventricles.
144
In the pacemaker cells, the SNS increases the heart rate by?
increased permeability of Na and Calcium increasing the slope of the membrane potential so the cells reach the threshold potential more quickly, the inside of the cell is more positive, depolarizing the membrane potential.
Increases the speed of contraction, by allowing a greater influx of CA through L-type of Calcium channels, and enhances the removal of Calcium ions from the cytosol so that relaxation occurs more rapidly following the contraction.
145
AT rest the _____ nervous system dominates our heart rate
PSNS
146
The stroke volume is the difference between what?
EDV-ESV.
147
on average the EDV is
120 mL
148
on average the ESV is around?
50 mL
149
The ventricles pump approximately \_\_% of blood in its chambers?
60%
150
Stroke volume is primarily influenced by three factors which are?
preload
contractility
afterload
151
The heart and blood vessels are controlled to provide the cardiac output and arterial pressure needed to supply?
adequate tissue blood flow
transport nutrients to tissues
Transport waste away
Transport hormones
152
circulation system is divided into two systems which are?
systemic and pulmonary circulation
153
the systemic circulation does what?
moves blood between the heart and the rest of the body
154
the pulmonary circulation does what?
moves blood between the heart and the lungs
155
what is the function of the arteries?
transport blood under high pressure to the tissues
156
why does arteries have strong vascular walls?
the arteries are under high pressure and high velocity
157
What is the function of the arterioles?
They act as control conduits through which blood is released into our capillaries,
158
arterioles have strong muscular walls which can do what?
close the arterioles completely or by relaxing can dilate the vessels several fold, meaning they can vastly alter blood flow in each tissue in response to its needs.
159
what is the function of the capillaries?
to exchange fluid, nutrients, electrolytes, hormones, and other substances between the blood and interstitial fluid
160
The capillary walls are _____ and have numerous minute ____ \_\_\_\_ that are permeable to water and other small molecular substances.
thin
capillary pores
161
what is the function of the venules?
function as conduits to transport of blood from the venules back to the heart
162
What is the function of the vein?
serve as a major reservoir of extra blood
163
why is the venous walls thin?
because the pressure in the venous system
164
even though the veins have thin walls, they are muscular enough to contract or expand to serve as a ?
controllable reservoir for the extra blood, either a small or large amount depending on the needs of our circulation.
165
Demands are not met by the heart alone but along with _____ and _____ \_\_\_.
microvessels and nervous system
166
Blood flow to most tissues is controlled according to the ______ needs.
tissues
167
Cardiac output is the sum of all the?
local tissue flows
168
when tissues are active, they need increased supply of nutrients and therefore more \_\_\_\_\_\_.
blood flow
169
blood pressure is dependent on what three factors?
blood viscosity
vessel length
vessel diameter
170
blood circulation is dependent on three factors which are?
blood flow
blood pressure
and resistance
171
blood flow is what?
the volume of blood flowing through vessel in a given time period.
172
blood flow is measured in?
mL/min
173
blood pressure what?
the force of blood exerted on the vessel wall
174
blood pressure is measured in?
mmHg
175
Resistance is what?
the opposition of blood flow as it moves through a vessel
176
The most occurs at the level of the __________ in the peripheral circulation.
arterials
177
The resistance at the level of the arterials is known as?
total peripheral resistance
178
the three factors that influence resistance are (3)?
blood viscosity
vessel length
vessel diameter
179
what is the blood viscosity?
the internal friction that exists in all fluid as the molecules slide over each other during the flow of fluid
180
The greater the viscosity the ____ the resistance to flow.
greater
181
blood viscosity is primarily determined by?
the number of circulating red blood cells.
182
when red blood cell count increases the viscosity and resistance is \_\_\_\_\_\_\_\_\_\_\_.
increased
183
The longer vessel length results in \_\_\_\_\_\_\_\_resistance.
greater
184
Obese individuals have a ___________ in their vessel length.
increase, thus their resistance is increased, and they increased number of smooth muscle cells surrounding the vasculature decreasing the vessel diameter and increasing their resistance.
185
Viscosity and vessel length remain relatively \_\_\_\_\_\_\_\_\_.
constant
186
the major determinant of resistance is?
vessel diameter
187
fluid passes through a ____ vessel more eaily than a _____ vessel. (vessel diameter)
larger
smaller
188
In a small radius vessel, more of a given volume of blood comes into contact with much more of the surface area than in a larger radius vessel, resulting in a ______ friction and resistance
greater
189
radius is directly proportional to _____ of the resistance
1/4
190
doubling the radius reduces the resistance to _____ its orginial value and increases the flow through the vessel \_\_\_\_fold
1/16th
16 fold.
191
Blood flow through a blood vessel is determined by which two factors?
pressure difference
resistance
192
pressure difference is also known as?
pressure gradiant
193
What is pressure difference?
P1-P2=pressure difference
P1= the pressure at the origin of the vessel
P2= pressure at the end of our vessel
194
Resistance occurs as a result of what?
friction between the flowing blood and the intravascular endothelial all along the inside of the vessel
195
Blood flow is inversely proportional to?
peripheral resistance
196
as you have an increase in the pressure difference, you are going to have a _____ in blood flow?
increase
pressure difference and blood flow are directly proportional
197
as you have an an increase in resistance, you are going to have a _____ in blood flow
decrease
198
blood flow is opposed by \_\_\_\_\_.
199
systemic resistance is the highest in the _____ and decreases to nearly _____ as it approaches the right atrium.
aorta
0
200
blood moves along a ______ \_\_\_\_\_ meaning from an area of higher pressure ot lower pressure area.
pressure gradiant
201
what is the diastolic pressure measuring?
the lowest aortic pressure, which is after the aortic valve closes, the elastic aorta recoils maintaining sufficient pressure to keep blood flowing florward in the distal vesslels and the aortic pressure drops to the lowest.
202
blood pressure is influenced by how elastic the arteries near the heart and the volume of blood ____ and _____ the artery
entering and leaving
203
The pulse pressure is what?
SBP-DBP= pulse pressure
204
as blood moves further away from the heart the pulse pressure \_\_\_\_\_.
narrows
205
is MAP or SBP a better indicator of perfusion to the vital organs?
MAP
206
what is the equation for MAP?
1/3 SBP + 2/3DBP=MAP
207
The three major blood pressure regulators are?
cardiac output
peripheral resistance
blood volume
208
the mechanisms that regulate blood pressure are separated into two categories known as?
short term and long term neural mechanisms
209
short term or faster controls of blood pressure, control blood pressure by altering ____ and \_\_\_\_.
PVR and CO
210
Short term mechanisms (neural control) control blood pressure by altering PVR and CO, but this is achieved two ways which are?
Vasoconstriction
heart rate
211
Neural controls of the vasomotor center recieve input from three places which are?
baroreceptors, chemoreceptors,and higher brain center
212
what is the vasomotor center, where is it located, and what does it do?
a cluster of nerves located in the medulla oblongata of the brainstem and they transmit signals along the sympathetic efferent nerves regulating blood pressure through vasoconstriction
213
Where are the baroreceptors located in the body?
in the aortic arch and in the walls of nearly every major artery in the neck and thorax.
214
if the baroreceptors are stretched they send signals to the _____ \_\_\_\_\_ to do what?
the vasomotor center
to vasodilate and reduce the PVR and subsequently decrease BP
215
A decrease in blood pressure causes the baroreceptor to send signals to the ________ \_\_\_\_\_ to do what?
vasomotor center
vasoconstric and increase CO to increase BP back to normal
216
chemoreceptors are located where and do what?
located in the aortic arch and the large arteries of the neck and measure oxygen and pH of the blood
217
given an example of a higher brain center that affects the vasomotor center?
hypothalamus
218
long-term mechanisms use the _____ system to control blood pressure.
renal
219
long-term mechanisms using the renal system control blood pressure by controlling _____ \_\_\_\_\_.
blood volume
220
blood volume is a major determinant of cardiac output through its influence on what three things?
venous return
end-diastolic volume
stroke volume
221
the kidneys control blood pressure by releasing \_\_\_\_\_.
renin
222
renin release triggered by low blood pressure, causes a cascade of events that produce?
angiotensin II
223
low blood pressure stimulates the RAAS system, describe it
kidneys-renin
liver-angiotensinogen
renin+angiotensinogen=angiotensin I
angiotensin I goes to the lungs and the ACE converts it to angiotensin II
angiotensin II is a potent vasoconstrictor, stimulates the adrenal cortex to produce aldosterone (which causes renal absorption of sodium), stimulates the posterior pituitary gland to produce ADH (which causes the kidneys to promote water reabsorption).
Thus, the net results the two hormones promote sodium and water reabsorption to increase blood volume and blood pressure.
224
