Chapter 49 Flashcards
(292 cards)
1
Q
Blood is what type of tissue?
A
connective tissue
2
Q
What is blood composed of?
A
plasma; different kinds of cells; formed elements
3
Q
What are blood platelets?
A
fragments of cells produced in bone marrow
4
Q
What are the three main functions of circulating blood?
A
transportation; regulation; protection
5
Q
Where in blood are nutrient molecules carried?
A
plasma
6
Q
How does the blood function as a regulator?
A
transports regulatory hormones from endocrine glands; participates in temperature regulation through contraction/dilation of blood vessels underneath epidermis
7
Q
What percentage of plasma is water?
A
92% of plasma is water
8
Q
What solutes are found in plasma?
A
nutrients; wastes; hormones; ions; proteins
9
Q
How are nutrients and wastes transported through blood?
A
dissolved in the plasma
10
Q
What are the predominant ions present in blood?
A
Na+, Cl-, HCO3-
11
Q
What other ions are found in trace quantities in the plasma?
A
Ca2+; Mg2+; Cu2+; K+; Zn2+
12
Q
What produces most of the plasma proteins?
A
the liver produces most of the plasma proteins
13
Q
Which protein is most predominant in plasma?
A
albumin
14
Q
What are the three most important plasma proteins?
A
albumin; alpha/beta globulins; fibrinogen
15
Q
What is the function of alpha/beta globulins?
A
serve as carriers of lipids and steroid hormones
16
Q
Which protein serves as a carrier of lipid/steroid hormones?
A
alpha/beta globulins
17
Q
What is the function of fibrinogen?
A
required for blood clotting
18
Q
What is serum?
A
blood plasma without fibrinogen
19
Q
What percentage of blood plasma is made up of proteins?
A
7%
20
Q
What percentage of plasma proteins is made up of albumin?
A
54%
21
Q
What percentage of plasma proteins is made up of globulins?
A
38%
22
Q
What percentage of plasma proteins is made up of fibrinogen?
A
7%
23
Q
What percentage of plasma is made up of other solutes?
A
1.5%
24
Q
What is the concentration of RBCs in blood?
A
4-6 million RBCs per mm^3 blood
25
What is the concentration of platelets in blood?
150,000-300,000 platelets per mm^3 blood
26
What is the technical name for platelets?
thrombocytes
27
What are the three formed elements in blood?
erythrocytes; leukocytes; thrombocytes
28
What is hematocrit?
fraction of total blood volume occupied by erythrocytes
29
What is the hematocrit in humans?
45%
30
Mature mammalian erythrocytes lack
nuclei
31
In vertebrates, hemoglobin is found
only in erythrocytes
32
In invertebrates, the oxygen-binding pigment is found
also in the plasma
33
What percentage of cells in human blood are leukocytes?
less than 1%
34
Which are larger, erythrocytes or leukocytes?
leukocytes
35
How are leukocytes different from erythrocytes?
they have nuclei; they can diffuse into and out of capillaries through intercellular spaces
36
What are the two broad categories of leukocytes?
granular leukocytes; non-granular leukocytes
37
Granular leukocytes include
neutrophils; eosinophils; basophils
38
Nongranular leukocytes include
monocytes; lymphocytes
39
In humans, which leukocyte is the most numerous?
neutrophils
40
Rank the prevalence of leukocytes in humans from most common to least common.
neutrophiles; lymphocytes; monocytes; eosinophils; basophils
41
Erythrocytes and most leukocytes descend from which progenitor cell?
myeloid stem cells
42
Lymphocytes descend from which progenitor cell?
lymphoid stem cells
43
What is the approximate diameter of a platelet?
3 micrometers
44
When a blood vessel is injured, what does the liver do?
releases prothrombin, which converts fibrinogen into insoluble fibrin, which aggregates to form a clot
45
Generally speaking, formed elements arise from
stem cells
46
(T/F) Formed elements have an finite life span.
True, formed elements have a finite life span
47
Old cell fragments are digested by
phagocytic cells of the spleen
48
All formed elements develop from
pluripotent stem cells
49
What is hematopoiesis?
production of blood cells occurring in the bone marrow
50
Hematopoiesis generates what two types of stem cells?
lymphoid stem cells; myeloid stem cells
51
When O2 available in the blood deceases, what does the kidney do?
converts plasma protein into erythropoietin (a hormone)
52
What is the function of erythropoietin?
stimulates production of erythrocytes from myeloid stem cells in process called erythropoiesis
53
What is erythropoiesis?
production of RBCs from myeloid stem cells when blood O2 is low
54
(T/F) Mature erythrocytes in all vertebrates are de-nucleated.
False, mature erythrocytes are de-nucleated only in mammals. Erythrocytes of all other vertebrates remain nucleated
55
What are megakaryocytes?
precursor cell of platelets (is pinched off)
56
What happens first when a blood vessel is broken/cut
smooth muscle in vessel wall contracts to constrict vessel
57
What happens second when a blood vessel is broken/cut?
platelets accumulate at injury site and form a plug
58
What happens third when a blood vessel is broken/cut?
prothrombin is converted to thrombin in the presence of platelets, and thrombin converts fibrinogen into fibrin which comes out of solution
59
What happens fourth when a blood vessel is broken/cut?
fibrin threads trap RBCs and form a clot
60
What happens fifth when a blood vessel is broken/cut?
once tissue damage is healed, clot is dissolved
61
Which organisms use water as their circulatory fluid?
sponges; most cnidarians
62
How do sponges circulate water as their circulatory fluid?
pass water through a series of channels in bodies
63
How do cnidarians circulate water as their circulatory fluid?
circulate water through a gastrovascular cavity which can work because the body wall is only 2 cells thick so each cell is either in direct contact w/ outside or gastrovascular cavity
64
Which organisms have pseudocoeloms?
roundworms; rotifers
65
What are the two main types of circulatory systems?
open; closed
66
Open circulatory systems are typically found in
mollusks; arthropods
67
What is the characteristic feature of open circulatory systems?
no distinction between circulating fluid and extracellular fluid of body tissues; fluid is called hemolymph
68
In insects, what pumps hemolymph?
heart
69
In insects, how does hemolymph "return" for oxygenation?
fluid drains back into the central cavity
70
Closed circulatory systems are typically found in
cephalopod mollusks; annelids; all vertebrates
71
What is the characteristic feature of closed circulatory systems?
blood is always inclosed within blood vessels and transport it to and away from the heart
72
In annelids, what pumps blood?
dorsal vessel contracts rhythmically; blood is pushed through 5 connecting arteries (which also serve as pumps) to a ventral vessel which transports blood posteriorly until re-entering dorsal vessel
73
Describe the heart in chordates.
simple tubular heart that was a specialized zone of the ventral artery that contracted in peristaltic waves
74
Describe the fish heart (generally).
a tube with four structures arrayed one after the other to form 2 pumping chambers
75
How many pumping chambers does the fish heart have?
2
76
What comprises the first chamber of the fish heart?
sinus venous; atrium
77
What comprises the second chamber of the fish heart?
ventricle; conus arteriosus
78
What is the order of contraction for the fish heart?
sinus venous; atrium; ventricle; conus arteriosus
79
In fishes, where does the electric impulse stimulating contraction originate?
originates in the sinus venosus
80
In all vertebrates except fishes, where does the electric impulse stimulating contraction originate?
sinoatrial (SA) node
81
What is the order for blood flow in fishes?
atrium > ventricle > conus arteriosus > gills > respiratory capillaries > systemic capillaries > sinus venosus
82
What is the serious limitation of the fish circulatory system?
when blood passes through capillaries in the gills, the blood pressure drops significantly, which slows circulation and limits oxygen delivery
83
Evolutionarily speaking, which circulatory system came after fishes?
amphibian
84
What is one major change introduced by the amphibian/reptile circulatory system?
double circulation - blood is pumped by heart to lungs via pulmonary artery and returns to heart via pulmonary vein to be sent to the body
85
What are the two components of double circulation?
pulmonary circulation; systemic circulation
86
What is pulmonary circulation?
movement of blood between heart and lungs
87
What is systemic circulation?
movement of blood between heart and rest of body
88
How does the amphibian heart prevent the mixing of oxygenated blood with deoxygenated blood?
atrium is divided into two
89
Describe the right and left atria in the amphibian heart.
right atria receives deoxygenated blood from body; left atrium receives oxygenated blood from lungs
90
How many ventricles does the amphibian heart have?
one
91
What is the consequence of the amphibian heart having only one ventricle?
separation of pulmonary and systemic circulation is incomplete
92
How do amphibians reduce the extent of mixing caused by the incomplete separation of the pulmonary and systemic circuits?
recesses in the ventricular wall; conus arterioles is partially separated by a dividing wall
93
The conus arteriosus directs blood into
deoxygenated blood goes into the pulmonary arteries whereas oxygenated blood goes to the aorta
94
What is the major artery of the systemic circuit?
aorta
95
What additional circulatory feature is present in amphibians who live in water?
pulmocutaneous circuit that sends blood to both the lungs and skin
96
Evolutionarily speaking, what came after the amphibian circulatory system?
reptile
97
What major circulatory modifications are present in reptiles?
they have separated atria AND partially divided ventricles; conus arteriosus is incorporated into trunks of large arteries leaving the heart
98
The crocodile's circulatory system is unusual in that
it has two completely separated ventricles divided by a complete septum (unlike all other reptiles)
99
How many chambers does the mammal/bird/crocodile heart have?
four chambers (two separate atria, two separate ventricles)
100
What explains the remarkable similarity between the hearts of birds and mammals?
convergent evolution
101
Describe the order of structures in the mammal/bird heart that blood goes through.
deoxygenated blood enters right atrium > right ventricle > pulmonary artery > lungs > pulmonary vein > left atrium > left ventricle > aorta
102
How many cycles are in each mammal/bird heart pump?
2
103
Describe the two-cycle pump in the mammal/bird heart.
both atria simultaneously contract, which empties blood into ventricles; in second cycle, both ventricles simultaneously push blood into pulmonary or systemic circuits
104
Why was the double circulatory system important, evolutionarily speaking?
allowed for the evolution of endothermy, which requires more efficient circulation to support high metabolic rate
105
What happens to the sinus venosus in the amphibian heart?
reduced in size from fish heart
106
What happens to the sinus venosus in the reptilian heart?
reduced in size from amphibian heart
107
What happens to the sinus venosus in the mammal/bird heart?
no longer present as separate chamber; some tissue remains in wall of right atrium
108
What is the pacemaker in the mammal/bird heart, and where is it located?
the sinoatrial (SA) node, located in wall of right atrium
109
The sinoatrial (SA) node is a derivative of
the sinus venosus in fish
110
What is the cardiac cycle comprised of?
the two contractions plus resting period between them
111
What are the two pairs of valves in the heart?
atrioventricular (AV) valve; semilunar valves
112
What do AV valves do?
maintain unidirectional blood flow between atria and ventricles
113
The AV valve on the right side is called
tricuspid valve
114
The AV valve on the left side is called
bicuspid (mitral) valve
115
What do the semilunar valves do?
ensure one-way flow out of ventricles into arterial systems
116
The semilunar valve on the right side is called
pulmonary valve
117
Where is the pulmonary valve located?
exit of right ventricle
118
The semilunar valve on the left side is called
aortic valvue
119
Where is the aortic valve located?
exit of left ventricle
120
When are the first set of valves open relative to the other set of valves?
the pulmonary and aortic valves are CLOSED when the tricuspid and bicuspid valves are OPEN (and vice versa)
121
What makes the Lub sound?
when the tricuspid and bicuspid valves shut
122
What makes the Dub sound?
when the pulmonary and aortic valves shut
123
The cardiac cycle begins as
blood returns to resting heart through veins that empty into right and left atria
124
What stimulates the the two AV valves to open as the atria fill with blood?
rising pressure in the atria stimulates AV valves to open
125
Are the ventricles completely filled with blood from the atria in one shot?
No, ventricles become 80% filled with blood when the AV valves open, but contraction of the atria tops up the remaining 20%
126
How much blood (in mL) does the ventricle receive, on average, in a resting person?
80 mL
127
What is the ventricular diastole?
period of time in which heart muscles relax and allows ventricles to fill with blood
128
What is the ventricular systole?
period of time in which ventricles contracts and pumps blood into arteries
129
What opens the semilunar valves?
the pressure/buildup of blood in the ventricles
130
What is the name for the structures that initiate action potentials for membrane depolarization?
autorhythmic fibers/cells, which are self-excitable muscle cells
131
What is the most important group of autorhythmic cells?
sinoatrial node
132
How does the SA node act as a pacemaker for the heart?
produces spontaneous action potentials at a faster rate than other autorhythmic cells
133
Why are the SA action potentials spontaneous?
because of constant leakage of Na+ ions into the cell that depolarize the membrane
134
How often does the SA node generate an action potential?
once every 0.6 sec = 100 times a minute
135
Each depolarization initiated by the SA node can be transmitted through what two pathways?
one to cardiac muscle fibers in left atrium; one to right atrium and AV node
136
Why is the rapid spread of depolarization in the heart possible?
there are special conducting fibers present; cardiac muscle cells are coupled by groups of gap junctions within intercalated disks
137
What prevents multiple chambers getting excited at once?
sheet of connective tissue separating atria from ventricles blocks spread of excitation
138
How is the depolarization from the atria to the ventricles transmitted?
via the AV node
139
When transmitting a depolarization from an atrium to a ventricle, what does the AV node do?
slows down the signal by 0.1 sec to let atria finish contracting and empty blood
140
Once the blood is in the ventricle, how does the AV node transmit the depolarization wave?
signal is sent to atrioventricular bundle
141
What is another name for the atrioventricular bundle?
bundle of His
142
What does the atrioventricular bundle do?
transmits the depolarization to Purkinje fibers
143
What do Purkinje fibers do?
stimulate myocardial cells of the left and right ventricles which causes contraction
144
Describe the overall path of signal transmission in the contraction of the heart.
SA node > AV node > AV bundle (bundle of His) > interventricular septum > Purkinje fibers > myocardial cells
145
Contraction of the heart muscle is controlled by what molecular-level system?
Ca2+ ions; troponin/tropomyosin system like in skeletal muscle
146
How is the shape of the action potential different in heart contractions?
rising phase due to influx of Na+; plateau phase leading to more sustained contraction due to opening of Ca2+ channels
147
Why is the opening of Ca2+ channels during the sustained contraction important?
keeps the membrane depolarized while the Na+ channels are inactive, which leads to more voltage-gated Ca2+ channels in the sarcoplasmic reticulum opening, which sustains the contraction
148
How is the Ca2+ removed from the cytoplasm?
by a pump in the sarcoplasmic reticulum (like in skeletal muscle); a carrier in the plasma membrane pumps Ca2+ into interstitial space
149
What graph shows the electrical activity of the heart?
electrocardiogram (EKG/ECG)
150
When taking an EKG, where are the electrodes placed?
limbs and chest
151
Depolarization of the heart causes
contraction
152
Depolarization of the heart causes
relaxation
153
The P wave of the EKG is produced by
depolarization of the atria
154
The P wave of the EKG is associated with
atrial systole
155
The Q-R-S wave of the EKG is produced by
depolarization of the ventricles
156
The Q-R-S wave of the EKG is associated with
ventricular systole
157
The T wave of the EKG is produced by
repolarization of the ventricles
158
The T wave of the EKG is associated with
ventricles beginning diastole
159
What do the pulmonary arteries do?
deliver deoxygenated blood from right ventricle to both right/left lungs
160
What do the pulmonary veins do?
delivery oxygenated blood from lungs to left atrium
161
What are the first branches off the aorta?
coronary arteries
162
What do the coronary arteries do?
supply oxygenated blood to heart muscle itself
163
The systemic veins empty in what two major veins?
superior (drains upper body) and inferior (drains lower body) vena cava
164
The superior/inferior vena cava empty into
right atrium
165
What does a sphygmomanometer do?
measures blood pressure in brachial artery found on the inside part of arm, above elbow
166
When the cuff is loosened, what happens to blood pressure?
eventually BP produced by heart is greater than constricting pressure of cuff so blood begins to flow
167
What is systolic pressure?
peak pressure at which ventricles are contracting (point when ventricles are contracting)
168
When the cuff is loosened further, what happens to BP?
pressure of cuff is lower than blood pressure throughout cardiac cycle
169
What is diastolic pressure?
minimum pressure between heartbeats (point when ventricles are relaxed)
170
In systolic/diastolic pressure, when are sounds heard?
no sounds heard when artery is always closed or artery always open; when artery alternates a pulse sound is heard
171
Blood pressure is written as
ratio of systolic over diastolic pressure
172
A healthy person in 20s should have a BP of
120/75
173
BP units are
mmHg
174
Hypertension is defined as
having a systolic pressure greater than 150 mm Hg OR a diastolic pressure greater than 90 mm Hg
175
What is the subdivision of arteries?
arterioles
176
What is the subdivision of veins?
venules
177
What is the innermost layer of arteries/arterioles/veins/venules?
endothelium (epithelial sheet)
178
What covers the endothelium of arteries/arterioles/veins/venules?
thin layer of elastic fibers; smooth muscle layer; connective tissue layer
179
What comprises the walls of capillaries?
only endothelium (to allow for diffusion)
180
What is the relationship between the diameter of a vessel and resistance to flow?
the narrower the vessel, the greater the frictional resistance to flow
181
A vessel that is half as narrow as another has what times the frictional resistance?
A vessel that is half as narrow as another has 16x frictional resistance
182
Which blood vessels provide the greatest resistance to blood flow?
small arteries and arterioles
183
High BP results from
chronic vasoconstriction
184
Vasoconstriction and vasodilation are important in regulating
body heat in both endo/ectotherms
185
Increasing blood flow to the skin has what effect on body heat?
increases rate of heat exchange
186
Decreasing blood flow to skin has what effect on body heat?
minimizes rate of heat exchange
187
Every cell in the body is within what distance of a capillary?
100 micrometers
188
How long are capillaries, on average?
1 mm long
189
What is the diameter of capillaries, on average?
8 micrometers in diameter
190
What is the diameter of an RBC?
5 to 7 micrometers
191
Which vessel has the greatest TOTAL cross-sectional area of any vessel?
capillaries, because there so many of them
192
Does blood travel through capillaries quickly or slowly?
quickly
193
Describe how velocity and pressure of blood flow change as it moves through arterioles/capillaries/venules.
blood pressure/velocity decrease as it moves through arterioles/capillaries, but blood velocity increases as cross-sectional area decreases in the venules
194
Most of the blood in the cardiovascular system is contained in which vessels?
in veins
195
(T/F) Veins can expand to hold additional amounts of blood.
true
196
What mechanisms are in place to help return blood to the heart from feet/legs?
skeletal muscles can contract to move blood by squeezing veins; venuous valves help blood move in one direction
197
What is the venuous pump?
when skeletal muscles surrounding veins contract to squeeze blood upwards
198
What are varicose veins?
veins in which there is too much blood such that the venuous valves stop working and blood pools in the veins
199
(T/F) The cardiovascular system is considered a closed system.
true, because all its vessels are connected with one another
200
A significant amount of water and solutes in blood plasma filter through capillary walls to become
interstitial (tissue) fluid
201
Where does the fluid containing water/solutes in blood plasma leave the capillaries?
near the arteriole end where pressure is higher
202
Where does the fluid containing water/solutes in blood plasma return to the capillaries?
near the venular ends
203
How does the fluid containing water/solutes in blood plasma return to the capillaries?
osmosis
204
High capillary BP can result in
too much interstitial fluid accumulating
205
Why do pregnant women's feet swell?
because their enlarged uterus compresses abdominal veins, which increases capillary BP, which results in increased interstitial fluid
206
What is edema?
swelling of the feet
207
Edema can result from
high capillary BP or low plasma protein concentration
208
Low plasma protein concentration can be caused by
liver disease; insufficient dietary protein
209
How does the fluid not returned to the capillaries return the cardiovascular system?
lymphatic system
210
What kind of system is the lymphatic system?
open circulatory system
211
The lymphatic system consists of
lymphatic capillaries; lymphatic vessels; lymphatic nodes; lymphatic organs
212
What are the two primary lymphatic organs?
spleen; thymus
213
Where does excess fluid in tissues go?
drains into blind-ended lymph capillaries with highly permeable walls
214
What is lymph?
fluid that drains into lymph capillaries (originates from excess fluid in tissues)
215
Describe lymphatic vessels.
resemble veins; have one-way valves
216
What are the two major lymphatic vessels?
right lymphatic duct; thoracic duct
217
Where do the two major lymphatic vessels drain?
left and right subclavian veins under the collarbones
218
How is lymph moved in mammals?
skeletal muscles squeeze against lymphatic vessels (like in veins)
219
(T/F) Lymphatic vessels can contract rhythmically.
True
220
What is a lymph heart?
structure that propels movement of lymph; found in fishes, all amphibians, all reptiles, bird embryos, some adult birds
221
What happens to lymph as it moves through lymph nodes/lymphatic organs?
modified by phagocytic cells
222
Lymph nodes and lymphatic organs contain
germinal centers
223
What are germinal centers?
sites where the activation and proliferation of lymphocytes occurs
224
What is the leading cause of death in the US?
cardiovascular diaseases
225
What is another name for atherosclerosis?
hardening of arteries
226
What is the directionality of lymph flow in lymph vessels?
one-way
227
What causes atherosclerosis?
accumulation within arteries of fatty materials, abnormal amounts of smooth muscle, deposits of cholesterol, deposits of fibrin, other debris
228
The accumulations within arteries results in what effect?
increased vascular resistance which impedes blood flow
229
How is cholesterol carried in the blood?
in lipoprotein complexes
230
What are the two observed forms of cholesterol lipoproteins?
low-density lipoprotein (LDL) and high-density lipoprotein (HDL)
231
Which lipoprotein is "good" cholesterol?
HDL
232
Which lipoprotein is "bad" cholesterol?
LDL
233
How do HDLs deal with cholesterol?
take cholesterol out of circulation and send it to the liver for elimination
234
How do LDLs deal with cholesterol?
transport cholesterol to all cells of the body
235
Why can LDLs be bad?
if cells have enough cholesterol, then the # of LDL receptors decreases, which leads to high levels of LDLs just circulating in blood, which can be deposited in blood vessels
236
Atherosclerosis is promoted by
genetic factors; smoking; high BP; cholesterol
237
What is arteriosclerosis?
when calcium is deposited in arterial walls
238
Arteriosclerosis tends to occur when
atherosclerosis is severe
239
What effect does arteriosclerosis have?
restricted blood flow; cannot expand like normal arteries; heart has to work harder
240
What is the formal name for heart attacks?
myocardial infarctions
241
Heart attacks result from
insufficient supply of blood to one or more parts of the heart muscle which causes myocardial cells to die; blood clots forming in coronary arteries
242
Is recovery from a heart attack possible?
Yes, if the portion that was damaged was small enough so that the heart can still function as a unit
243
What does angina pectoris mean?
chest pain
244
What causes angina pectoris?
same reasons as heart attack, but not as severe
245
Where does angina pectoris pain often occur?
left arm and shoulder
246
Strokes are caused by
interference with blood supply to brain
247
What are the two most common types of strokes?
hemorrhagic stroke; ischemic stroke
248
What is a hemorrhagic stroke?
when a blood vessel bursts in the brain
249
What is an ischemic stroke?
when blood flow in a cerebral artery is blocked by a blood clot or atherosclerosis
250
(T/F) The autonomic nervous system initiates heartbeat.
FALSE. It doesn't.
251
If the autonomic nervous system doesn't initiate heartbeat, what does it control?
regulates rhythm and force of contraction
252
Heart rate is under the control of
the autonomic nervous system
253
The cardiac center consists of what two neuronal centers that control heart rate?
cardioacceleratory center; cardioinhibitory center
254
What does the cardioacceleratory center do?
secretes norepinephrine to increase heart rate
255
Where does the cardioacceleratory center send signals?
SA node; AV node; myocardium
256
What does the cardioacceleratory center use to send signals?
sends signals by way of sympathetic cardiac accelerator nerves
257
What effect does norepinephrine have on heart rate?
increases heart rate
258
(T/F) Only the autonomic nervous system can increase contractility of the heart its.f
False, the sympathetic nervous system can be stimulated to increase contractility of heart muscle
259
What does the cardioinhibitory center do?
secretes acetylcholine, which slows heart rate by inhibiting formation of action potentials
260
Where does the cardioinhibitory center send signals?
SA node; AV node
261
What does the cardioinhibitory center use to send signals?
sends signals via parasympathetic fibers in vagus nerve
262
Which nerve secretes acetylcholine?
vagus nerve
263
What is cardiac output?
volume of blood pumped by each ventricle per minute
264
How is cardiac output calculated?
multiplying heart rate by stroke volume
265
What is stroke volume?
volume of blood ejected by each ventricle per beat
266
What is the average cardiac output in humans?
5 L/min
267
During exercise, cardiac output can increase to
25 L/min, but not all target organs receive 5x the blood
268
The arterial blood pressure (BP) depends on what two factors?
cardiac output (CO); resistance (R) to blood flow
269
What is the equation relating BP, CO, and R?
BP = CO x R
270
What detects changes in arterial blood pressure?
baroreceptors
271
Where are the baroreceptors located?
arch of aorta; carotid arteries
272
How do baroreceptors measure blood pressure?
detect expansion and contraction of arteries
273
What happens when baroreceptors detect a fall in blood pressure?
number of impulses to cardiac center decreases; results in increased sympathetic stimulation and decreased parasympathetic stimulation
274
What effect does a fall in blood pressure have on heart rate, stroke volume, and resistance?
increases heart rate, stroke volume, and resistance
275
What happens when baroreceptors detect an increase in blood pressure?
number of impulses to cardiac center increases; results in decreased sympathetic stimulation and increased parasympathetic stimulation
276
Baroreceptor feedback is what kind of feedback?
negative feedback loop
277
What four hormones regulate blood volume?
ADH; aldosterone; atrial natriuretic hormone; nitric oxide
278
What is another name for ADH?
vasopressin
279
What secretes ADH?
posterior-pituitary gland
280
When is ADH secreted?
in response to an increase in osmolarity of blood plasma
281
What receptors detect the need to secrete ADH?
osmoreceptors in the hypothalamus
282
What happens when kidneys experience decreased blood flow?
kidney cells initiate release of renin into blood
283
What does renin do?
activates angiotensin which stimulates vasoconstriction; stimulates adrenal cortex to secrete aldosterone
284
What does aldosterone do?
promotes retention of water/Na+ in kidneys
285
What is the effect of excess Na+ on aldosterone?
less aldosterone is secreted by adrenals
286
What secretes aldosterone?
adrenal cortex/adrenal glands
287
Na+ excretion in urine is promoted by
atrial natriuretic hormone
288
What does atrial natriuretic hormone do?
promotes Na+ excretion in urine
289
What secretes atrial natriuretic hormone?
right atrium of heart
290
When is atrial natriuretic hormone secreted?
in response to stretching caused by increased blood volume
291
What produces NO?
endothelial cells of blood vessels
292
What does NO do?
causes smooth muscle to relax and vessels to dilate
