Exam 1 Flashcards
1
Q
cardiovascular system
A
comprised of heart and blood vessels
2
Q
Blood transports
A
oxygen, nutrients and hormones
3
Q
clotting mechanism
A
protects the body against loss of blood following injury
4
Q
phagocytic white blood cells
A
engulf and destroy invading microorganisms and toxins
5
Q
antibodies
A
neutralize and/or destroy pathogens
6
Q
inflammation
A
limits the spread of infection
7
Q
Blood buffers
A
maintain constant pH levels
8
Q
blood flow
A
maintains normal body temperature
9
Q
blood volume
A
maintains water balance through the body
10
Q
blood constitutes what percent of ones total weight?
A
8%
11
Q
average female
A
has 4 to 5 liters of blood
12
Q
averge male
A
has 5 to 6 liters of blood (because they are generally larger)
13
Q
blood is
A
Connective tisse
14
Q
55% of the total blood volume
A
is clear extracellular fluid called plasma
15
Q
45% of the total blood volume
A
consists of formed elements
16
Q
formed elements in blood
A
red blood cells, white blood cells, platelets
17
Q
blood viscosity
A
blood is 4.5 to 5.5 more viscous than water, because of the presence of formed elements and plasma proteins
18
Q
blood viscosity effects
A
its flow through the blood vessels
19
Q
blood pH
A
slightly alkaline with normal pH ranging from 7.35 to 7.45
20
Q
blood osmolarity
A
is an important factor in maintaining fluid balance with the tissues
21
Q
blood osmolarity is determined by
A
the number of red blood cells, sodium ions, and proteins
22
Q
proteins
A
(BCOP) establish blood colloid osmotic pressure
23
Q
if blood osmolarity is TOO HIGH
A
too much water could be absorbed from the tissues, would cause blood volume to increase and blood pressure to rise (harder to circulate blood)
24
Q
is blood osmolarity is TOO LOW
A
too much water could remain in the tissues causing edema
25
blood plasma
straw colored fluid consisting of about 92% water and 8% solutes
26
blood serum
remains after clotting proteins (fibrinogen/the solutes) are removed from blood plasma
27
Albumins
blood protein; (60%) contribute mainly to viscosity and osmolarity; thus influencing blood flow, blood pressure, and water balance
28
Alpha globulins
blood protein; (36%) TRANSPORT lipids, fat soluble vitamins, minerals, hormones, iron and lipids
29
beta globulins
TRANSPORT iron and lipids
30
immunoglobulins
are antibodies that combat pathogens
31
fibrinogen
blood protein; (4%) becomes fibrin, which is the main component of blood clotting
32
Nitrogenous wastes
dissolved solute in plasma; including urea, transports wastes away from the cells
33
nutrients
dissolved solute in plasma; glucose, amino acids, fats, cholesterol; transports nutrients to the cells
34
Carbon dioxide and oxygen
dissolved solutes in plasma; blood gases/gas exchange
35
electrolytes
dissolved solute in plasma; sodium ions, chloride ions. bicarbonate ions
36
Erythrocytes
biconcave disks that lack nuclei and organelles (RED BLOOD CELLS)
37
erythrocyte plasma membrane
is permeable and flexible enough to permit cells to change shape as they squeeze through narrow cappilaries
38
red blood cells
carry out anaerobic respiration; thus they do not consume the oxygen they are transporting
39
red blood cells
cannot carry out protein synthesis and do not undergo mitosis (no nucleus)
40
1/3 of the weight of and erythrocyte is due to the protein
hemoglobin
41
hemoglobin
carries 4 oxygen molecules on its iron heme, gives blood its color
42
each hemoglobin molecule
consists of 4 protein globulin chains, each chain combines with non-protein heme group
43
each heme group
contains an iron ion that can transport one oxygen molecule
44
each erythrocyte contains up to 280 million hemoglobin molecules
enabling it to transport up to one billion molecules of oxygen
45
when oxygen is bound to hemoglobin
the complex is called oxyhemoglobin
46
hemoglobin that lacks oxygen
is called deoxyhemoglobin
47
hemoglobin is packed into erythrocytes to
reduce blood osmolarity, to increase gas transport, to prevent its leakage from capillary blood vessels
48
number of hemoglobin molecules per erythrocyte
would clog blood stream and reduce circulation if they were suspended in plasma (why they arent in plasma)
49
safe levels of free hemoglobin in the blood
could not transport enough oxygen
50
hematocrit
is the percentage of whole blood volume that comes from erythrocytes
51
ranges of hematocrit
42%-52% in males
| 37%-48% in females
52
lower hematocrit in females
is due to lower androgen (testosterone) levels, higher percentage of body fat, menstration during reproductive years
53
erythrocytes arise from
hemocytoblasts in red bone marrow that undergo erythropoiesis
54
kidneys and liver
release the hormone erythropoietin to stimulate proerythroblasts to differentiate and become mature erythrocytes over 15 days
this process requires; dietary iron, transfer and binding proteins, vitamin b12 and folic acid
55
hypoxemia
reduction in blood oxygen levels; causes kidneys to increase output of EPO to stimulate production of more red blood cells
56
blood doping
blood removed and then put back in to increase oxygen levels before sports
57
life span of red blood cells
is 120 days due to wear and tear on its plasma membrane
58
old erythrocytes
are removed from circulation by the liver and spleen
59
hemolysis
releases the hemoglobin an separates it into globins and heme groups
60
globins
are broken down into amino acids which get recycled
61
iron
is removed from the heme group to be reused; rest of the heme group is converted into waste bilirubin (comes out in feces)
62
human ABO blood types
are due to the presence or absence of proteins on the surface of an erythrocyte determined by the alleles I a, I b, and i
63
individuals with genotype IAIA or IAi
produce only antigen A and have blood type A (40% of white people)
64
individuals with genotype IBIB or IBi
produce only antigen B and have blood type B (11% of white people)
65
individuals with genotype IAIB
produce both antigen A and B and have blood type AB (4% of white people)
66
individuals with genotype ii
produce neither antigen A nor B and have blood type O (45% of white people)
67
agglutinins
blood plasma's naturally occurring antibodies, that will react with a or b antigens and cause clumping among erythroytes
68
individuals with antigen A
will have anti-B antibodies in their plasma
69
individuals with antigen B
will have anti-A antibodies in their plasma
70
individuals with both antigens A and B
will have NO antibodies in their plasma
71
individuals WITHOUT antigens
will have both anti-A and anti-B antibodies in their plasma
72
transfusion reaction
can occur when erythrocytes in transfused blood clump together and rupture because of the agglutinins in the recipients plasma
73
donor antibodies
are usually too dilute to cause clumping in the recipients blood
74
type AB blood
has neither anti-A nor anti-B antibodies in the plasma, so theoretically they are universal recipients
75
type O blood
lacks both antigens on red blood cells, so theoretically they are universal donors
76
the Rh blood group was first identified in the blood of the
rhesus monkey
77
individuals who have D antigens present on their red blood cells
are Rh+
78
anti-D antibodies
arent naturally present in blood plasma, and will develop only in Rh- individuals who have been exposed to D antigens ad sensitized
79
Granular leukocytes
tend to be larger than erythrocytes, have conspicuous nuclei and stained organelles in the cytoplasm, and exhibit a grainy appearance
80
neutrophils
make up 60% to 70% of a white blood cell count, and the count will be high in a bacterial infection
81
neutrophil cytoplasm
appears light purple and granules stain from pink to red
82
neutrophil nucleus
may exhibit two to five lobes of different shapes; creating polymorphonuclear leukocytes
83
neutrophil functions
- phagocytize bacteria
| - release antimicrobial substances
84
eosinophils
make up 2%-4% of white blood cell count, high in allergic reactions
85
eosinophil cytoplasm
cytoplasmic granules stain from bright red to orange
86
eosinophil nucleus
usually exhibits two distinct lobes
87
eosinophil function
- release enzymes to combat inflammation during allergic reactions
- protect against certain kinds of parasitic worms
88
basophils
make up less than 1% of a white blood cell count
89
basophil nucleus
is bilobed or "s" shaped; often obscured by cytoplasmic granules
90
basophil cytoplasm
cytoplasmic granules stain from dark blue to purple
91
basophil function
- secrete histamine to increase blood flow
| - secrete heparin to reduce blood clotting
92
Agranular leukocytes
tend to be larger than erythrocytes, have darkly stained nuclei, and lack cytoplasmic granules
93
Lymphocytes
make up 25% - 33% of a white blood cell count
| -its nucleus is dark violet and surrounded by a thin ring of blue stained cytoplasm
94
lymphocyte functions
- destroy cancer cells, cells infected with viruses, and foreign cells
- secrete antibodies durring immune responses
95
monocytes
make up 3% - 8% of a white blood cell count
| -nucleus is horseshoe shaped or kidney shaped and cytoplasm is blue-gray
96
monocyte function
- differentiate into macrophages that leave blood to phagocytize pathogens, dead neutrophils and tissue debris
- activate immune response
97
white blood cells are produced by
leukopoiesis ; which is stimulated by various chemical messengers such as interleukins or colony-stimulating factors
98
hemocytoblasts differentiate into different types of committed precursor cells
myeloblasts, monoblasts, lymphoblasts
99
myeloblasts
differentiate into different types of granulocytes
100
monoblasts
differentiate into monocytes
101
lymphoblasts
give rise to all types of lymphocytes
102
red bone marrow
stores granulocytes and monocytes until they are needed
103
some lymphocytes mature in
the thymus gland
104
there are between 5,000 and 10,000 white blood cells
per microliter of blood
105
the life span of a leukocyte is
relatively short because of its role in phagocytosis
106
differential white blood cell count
compares the percentage of each type of leukocyte to the total white blood cell count
107
use of the differential white blood cell count
can be used to identify infection or inflammation, to monitor blood disorders, or to determine the effects of drugs or chemotherapy
108
Platelets
are membrane enclosed cytoplasmic fragments of larger cells and lack nuclei
109
platelet functions
- secrete chemicals to stop bleeding and to promote blood clotting
- phagocytize bacteria (not as well as neutrophils/monocytes)
- attract neutrophils and monocytes to the cite of inflammation
110
platelets are produced by
thrombopoiesis
111
megakaryoblasts
grow larger and larger until the cytoplasm breaks into fragments
112
thrombopoietin
stimulates magakaryoblasts to become megakaryocytes in red bone marrow
113
normal platelet count
ranges from 130,000 to 400,000 per microliter of blood
114
most platelets circulate freely in the blood for
about 10 days
115
Hemostasis
refers to the stoppage of bleeding in damaged blood vessels
116
vascular spasm
can be triggered by chemicals released from the walls of blood vessels to contract and constrict the vessels for a few minutes until other hemostatic mechanisms begin
117
Platelet plug
damage to a blood vessel exposes collagen fibers in the wall of the vessel so circulating platelets can adhere to these fibers and form a platelet plug
118
platelets release chemicals
causing additional platelets to form a sticky mass that activates positive feedback loops to quickly prevent blood loss from small vessel
-extremely important in controlling microhemorrage
119
coagulation
the conversion of blood from a liquid to a sticky gel
120
injury to a blood vessel
requires the activation of various coagulation factors in order to trigger the "clotting cascade"
121
"clotting cascade"
converts clotting factors into enzymes in a sequence to act as amplifying mechanism to ensure rapid clotting
122
the extrinsic pathway
is initiated by clotting factors released from a damaged blood vessel or from the tissues around a damaged blood vessel (outside of the blood)
123
tissue thromboplastin
combines with a clotting factor in the presence of calcium ions to activate factor X
124
the extrinsic pathway can be triggered within
a matter of seconds in cases of severe trauma
125
the intrinsic pathway
is initiated by substances in blood plasma that cause aggregated platelets to release PF3
126
the substances that initiate the intrinsic pathway
activate a cascade of reactions, also requiring calcium ions, that activate factor X
127
the intrinsic pathway process is
more complex and operates more slowly than the extrinsic pathway, but both pathways usually work together following injury
128
The common Pathway
begins when factor X combines with other factor and calcium ions to produce the enzyme prothrombinase (prothrombin activator)
129
prothrombinase
catalyzes conversion of prothrombin to thrombin
130
thrombin
converts soluble fibrinogen to insoluble fibrin threads to form sticky framework of a blood clot
-also accelerates the formation of prothrombinase by positive feedback
131
Normal blood clotting
requires VITAMIN K to synthesize several clotting factors in the liver
132
within 30 minutes of clot formation
clot retraction tightens the fibrin threads and pulls the edges of the damaged vessel together so permanent repair of the vessel can occur
133
fibrinolysis
dissolves the clot following repair of the damaged blood vessel
134
tissue plasminogen activator (t-PA) (plasma enzyme) (kallikven)
converts inactive plasminogen into plasmin (given to stroke victims immediately to break up the clots responsible)
135
plasmin
digests fibrin threads and breaks up blood clot
136
endothelial cells that line the undamaged blood vessels produce
prostaglandin to prevent platelets from adhering to the walls of the blood vessel
137
normal blood flow
is fast enough to prevent thrombin and other clotting factors from accumulating and triggering the "clotting cascade"
138
anticoagulants in blood plasma can interfere with
the clotting cascade
139
antithrombin
deactivates thrombin before it can convert fibrinogen to fibrin
140
heparin
interferes with the formation of prothrombinase, which blocks conversion of prothrombin into thrombin
141
aspirin
interferes with enzymes that catalyze the synthesis of prostaglandins, thus slowing clot formation by blocking platelet aggregation
142
Polycythemia
an erythrocyte disorder, characterized by a very high erythrocyte count and hematocrit
143
primary polycythemia
is caused by cancer in the red bone marrow and can produce red blood cell count in excess of 11 million, creating a hematocrit of 80%
144
secondary polycythemia
can be caused by severe dehydration or hypoxemia
145
consequences of polycythemia
increases blood volume, blood viscosity, and blood pressure, which can lead to reduced circulation
146
anemia
describes any decrease in the oxygen carrying capacity of the blood due to a drop in the number of erythrocytes or an insufficient amount of hemoglobin
147
iron deficiency anemia
the most common nutritional disorder in the world, results from insufficient iron in the body
148
iron deficiency anemia affects
toddlers, adolescent girls, females of child bearing age because of menstration and nutritional demands of pregnancy
149
iron deficiency anemia is caused by
dietary insufficiency or impaired absorption or chromic blood loss
150
pernicious anemia
results from insufficient intrinsic factor needed to absorb vitamin b12 from the small intestine (for erythropoiesis)
151
pernicious anemia affects
strict vegetarians and elderly individuals
152
hemorrhagic anemia
results from excessive blood loss through injury, ulcers, or heavy menstration
153
hemolytic anemia
occurs when erythrocytes rupture from toxins, venoms, allergic reactions, or malaria
154
aplastic anemia
occurs when red bone marrow is destroyed and erythropoiesis halts
155
thalassemia
describes a group of hereditary anemias among mediterranean peoples that causes a deficiency or complete absence of hemoglobin
156
sickle cell disease
is a hereditary defect in the structure of hemoglobin molecules that is common among africans
-erythrocytes become sickled and sticky and block capillaries
157
in sickle cell disease subsequent reduction in circulation leads to
fatigue, weakness, pain, disorientation; can cause kidney failure, heart failure, stroke, paralysis
158
sickle cell trait
produces fewer deformed erythrocytes and offers carriers some resistance to malaria
-protection against malaria outweighs risk of developing sickle cell disease, so HBS gene has persisted among populations in tropical regions
159
Hemolytic disease of the newborn
can only occur if an Rh- woman becomes pregnant with an Rh+ fetus
-durring childbirth, Rh antigens from the fetus can cross placenta and enter mothers blood stream
160
subsequent pregnancy with an Rh+ fetus
becomes dangerous because anti-D antibodies from the mothers immune system can cross the placenta into the fetal bloodstream and clump large numbers of red blood cells
161
prevention of damage in subsequent pregnancy with an Rh+ fetus
injecting serum containing anti-D antibodies into and Rh- woman within 72 hours after delivery, miscarriage, or abortion of Rh+ fetus
162
anti-D antibodies (in serum)
destroy any fetal Rh antigens in mothers bloodstream before they can sensitize mothers immune system
163
Leukopenia
indicates an abnormally low white blood cell count
- often a consequence of lead poisoning or mercury poisoning
- often a symptom of radiation sickness
- may be a side effect of anti-cancer drugs or immunosuppressive drugs given to transplant recipients
164
infectious mononucleosis
is a contagious disease caused by the Epstein-Barr virus invading B lymphocytes
- usually transmitted by exchanging saliva
- symptoms include fever, sore throat, and swollen lymph nodes
- liver and/or spleen are effected
165
Leukemia
is a hemopoietic cancer that produces too many circulating leukocytes
166
myeloid leukemia
too many granulocytes
167
lymphoid leukemia
too many agranulocytes
168
acute leukemia
there is uncontrolled production and accumulation of immature, poorly differentiated leukocytes
169
chronic leukemia
there is an accumulation of mature leukocytes that do not die at the end of their normal life span; proliferation of later cell types among older individuals
170
decline in the number of functional leukocytes
increases risk for developing opportunistic infections
171
decline in the number of erythrocytes
can cause anemia and fatigue
172
decline in the number of platelets
can cause clotting problems and internal bleeding
173
Thrombocytopenia
indicates a very low platelet count that results in a tendency to bleed from the capillaries
174
hemophilia
describes a group of hereditary diseases that are caused by an x-linked recessive gene that produces bleeding and reduced clotting ability
175
hemophilia cause;
a lack of factor VIII followed by a lack of factor IX
| -treatment involves transfusing the missing coagulation factors
176
clot formation may occasionally occur
in an unbroken blood vessel
177
thrombus
is a blood clot that grows large enough to block a small blood vessel
178
embolus
if a piece of a thrombus breaks loose ad travels through the blood stream it becomes and embolus
179
if an embolus becomes lodged in an artery that supplies a major organ
disruption of blood flow to this organ could be fatal
180
pulmonary emboli
emboli are common in veins in arms and legs and travel to lungs where they can cause pulmonary embolism and death from hypoxia
181
the heart pumps blood through
thousands of miles of blood vessels
182
the heart is located
in the thoracic cavity beneath sternum in mediastinum between the lungs; its apex points down wards and toward left hip
183
size of heart
hollow cone shaped organ about the size of a closed fist
184
pericardium
is a sac that surrounds and protects the heart
185
parietal pericardium
forms the sac and consists of tough fibrous layer of dense irregular CT and thin smooth serous layer
*****it anchors the heart in the mediastinum and prevents over stretching******
186
visceral pericardium
covers the surface of the heart (literally touching the cardiac muscle)
187
pericarditis
describes inflamed pericardium due to bacterial infection or viral infection
-membranes may stick together and interfere with pumping ability of heart
188
outer epicardium(visceral pericardium)
is the thin serous membrane of mesothelium and areolar connective tissue
189
middle myocardium
is thick layer of cardiac muscle bound together with collagen fibers and elastic fibers
-cardiac muscle that triggers contractions that pump blood out of the heart
190
inner endocardium
is the layer of endothelium and CT
-lines chambers of the heart, covers valves, is continuous with inner lining of large blood vessels associated with heart
191
chambers of the heart
there are two superior chambers (atria) that receive blood from veins
192
each atrium has a small flap like structure called an
auricle that increases its capacity to hold blood
193
interatrial septum
atria have thin walls and are separated from one another by an interatrial septum
194
there are two inferior chambers that
pump blood into arteries
195
ventricles
have thick walls and are separated by a muscular interventricular septum
196
heart valves
passively control the direction of blood flow through the heart (one way flow)
197
heart valves consist of
two or three flaps of tissue called cusps
198
atrioventricular (AV) valves
are composed of dense connective tissue; they separate the atrium from its corresponding ventricle
199
right (AV) valve
is tricuspid valve with three cusps
200
left (AV) valve
is bicuspid (mitral valve) with two cusps
201
AV valve attachment
are anchored to the walls of the ventricle by chordae tendineae that attach to papillary muscles in walls of ventricle
202
semilunar valves
are found at the base of each large artery that emerges from the heart
203
pulmonary semilunar valve
opens the pulmonary trunk
204
aortic semilunar valve
opens into aorta
205
semilunar valves consist of
3 cusps of dense connective tissue attached directly to wall of artery
206
oxygen poor blood from the head, neck, and chest region
enters the right atrium through superior vena cava
207
oxygen poor blood from the legs and trunk
enters the right atrium from the inferior vena cava
208
blood flow
through tricuspid valve into right ventricle
209
when right ventricle is full
it exerts more pressure than right atrium and tricuspid valve is forced shut
210
blood is pumped
through pulmonary semilunar valve into pulmonary trunk to be carried into lungs via pulmonary arteries for oxygenation
211
oxygen rich blood
returns to heart via pulmonary veins to left atrium
212
blood flow through bicuspid valve
into left ventricle
213
blood is pumped out through
aortic semilunar valve into aorta to be delivered to rest of body
214
cardiac muscle must receive
a constant supply of blood
215
the ascending aorta gives rise to the
left and right coronary arteries
216
the coronary arteries
branch to supply blood to myocardium (left and right coronary arteries)
217
blood returns to the cardiopulmonary circulation via
2 pathways
218
about 20% of the coronary blood empties directly into
right ventricle
219
remaining blood passes through
cardiac veins to coronary arteries and into right atrium
220
cardiac muscle histology
has short, thick, branching cells (myofibers) each with one central nucleus
221
sarcoplasmic reticulum
is less developed than in skeletal muscle, but it contains larger t-tubules to admit more calcium ions from extracellular fluid
222
cardiac muscle fibers are joined end to end by
intercalated disks
223
desmosomes
hold muscle fibers together
224
gap junctions
allow action potentials to spread from one cardiac fibr to the next fiber
225
cardiac muscle contains more
myoglobin and more mitochondria than skeletal muscle
226
aerobic respiration
cardiac muscle almost only uses aerobic respiration because it is less prone to fatigue
227
cardiac muscle fibers are autorythmic and can
depolarize automatically to generate action potentials
228
excitation of cardiac muscle begins in the
Sinoatrial (SA) node, which is located in the right wall of the atrium just below the opening from the superior vena cava
229
SA node functions as a
pacemaker of the heart to initiate each heartbeat and set sinus rhythm for entire heart
230
Each cardiac action potential spreads from
SA node throughout both atria by way of gap junctions, causing both atria to contract simultaneously
231
the nerve signal spreads to the
Atrioventricular (AV) node in the interatrial septum
232
brief time delay as the nerve signal passes through
the (AV) node in the interatrial septum of .1 second
233
the nerve signal passes into the atrioventricular bundle (bundle of HIS) a tract of
conducting fibers that is the only electrical connection between the atria and ventricles
234
the atrioventricular bundle divides into
right and left bundle branches, which carry the nerve signal along either side of the interventricular septum toward the hearts apex
235
large diameter conduction myofibers
or purkinje fibers
236
purkinje fibers conduct
the nerve signal from the bundle branches into the ventricular myocardium
237
cardiac muscle contraction can automatically
depolarize
238
cells in the SA node gradually depolarize due to
a slow inflow of sodium ions and minimal out flow of potassium ions; generating a pacemaker potential
239
pacemaker potential threshold
when it reaches its threshold of -40mV, voltage regulated "fast calcium channels" open and calcium ions rush in to trigger action potential
240
when the nerve signal has concluded
pacemaker potential starts over to produce next heart beat
241
time for nerve signal to reach AV node
it takes about 50milliseconds for the nerve signal to reach the AV node where it is momentarily delayed to allow the ventricles to fill prior to contracting
242
sodium
=pacemaker potential
243
calcium
= action potential
244
myocardial contractions
signals travel fastest through the AV bundle and purkinje fibers and trigger the myocardial contractions that begin at the apex of the heart
245
cardiac muscle cells depolarize
very rapidly, because voltage - regulated sodium channels open and close very quickly
246
opening sodium channels also opens
calcium channels to trigger release of calcium ions from sarcoplasmic reticulum
247
voltage regulated potassium channels
open and potassium ions rush out which returns membrane to resting potential
248
cardiac muscle cells have a very long absolute refractory period which
prevents wave summation and tetany that would halt pumping action of the heart
249
absolute refractory period lasts
15 to 100 milliseconds
250
the electrocardiogram
is a graphic recording of the electrical changes that accompany a heartbeat
251
P wave
is a small upward wave produced by depolarization of the atria following spontaneous initiation of an action potential in the SA node
252
atrial contraction occurs about
.1 second after the P wave begins
253
QRS complex
is produced when the AV node fires and the ventricles depolarize as the impulse travels through the purkinje fibers
254
complicated shape of the QRS complex
is due to the fact that the left ventricle is larger than the right ventricle and depolarizes at a slightly different rate
255
ventricular contraction occurs during the
S-T segment
256
during the S-T segment
ventricular myoccytes are in plateau phase
257
atrial repolarization
also occurs during the S-T period of time but it is masked by the depolarization of the ventricles
258
T wave
is produced when the ventricles repolarize before they start to relax
259
both atria contract ( at the same time )
atrial systole
260
while atrial systole is happening; both ventricles
relax ( ventricular diastole )
261
when both ventricles contract
(ventricular systole) both atria relax ( atrial diastole )
262
systole
contract
263
diastole
relax
264
heard sounds occur because
of blood turbulence while valves are closing
265
lubb sound
of a heart beat occurs when the AV valves are closing and ventricular systole begins
266
dupp sound
occurs when the semi lunar valves snap shut at beginning of ventricular diastole
267
phases of the cardiac cycle
1. ventricular filling
2. isovolumetric contraction
3. ventricular ejection
4. isovolumetric relaxation
268
ventricular filling occurs after
the AV valves open
269
ventricular filling begins
rapidly, slows down, and finishes by the time atrial systole occurs
270
end-diastolic volume is
130ml, but only 30% is due to atrial systole, most blood is transferred to the ventricle by gravity
271
isovolumetric contraction
occurs when the ventricles start to contract, but dont eject any blood because all 4 valves are closed
272
in isovolumetric contraction, aortic and pulmonary pressure
exceed ventricular pressure
273
ventricular ejection occurs when
a ventricular pressure increases enough to open the semilunar valves and force blood into the aorta and the pulmonary trunk
274
end systolic volume
after ventricular ejection is about 60ml
275
isovolumetric relaxation occurs when
the ventricles start to relax, but dont fill with blood because all 4 valves are closed
276
each cardiac cycle pumps
70ml of blood out
277
cardiac output
describes the volume of blood ejected from each ventricle each minute and it is calculated from stroke volume and heart rate
278
cardiac output is calculated from
stroke volume and heart rate (CO=SV x HR)
279
stroke volume
is the amount of blood ejected by each ventricle during ventricular systole
280
heart rate averages
75 beats per minute
281
average cardiac output for a resting adult
is about 5.25 liters/minute
282
stroke volume is governed by three factors
1. preload
2. contractility
3. afterload
283
preload
is the degree to which cardiac muscle cells stretch just before they contract
284
anything that increases the volume of blood that returns to the heart or the speed at which blood returns to the heart will
increase preload
285
frank-starling law of the heart
greater end diastolic volume will cause cardiac muscle fibers to stretch more and generate greater contractile force
286
cardiac muscle length-tension relationship
resting cardiac muscle fiber are normally shorter than optimal length in order to develop maximum tension (improves force of blood movement)
287
contractility
is the contractile force that gets developed for a particular preload
288
increased contractility
increases stroke volume
289
positive inotropic agents (epinephrine/digitalis) increase
contractility by making more calcium available; increases length of plateau and allows more contractile force to develop
290
negative inotropic agents (potassium/calcium channel blockers)
reduce contractility by reducing amount of calcium that get released
291
afterload
is the pressure that is needed to open the semilunar valves
292
increased afterload
decreases stroke volume
293
heart rate is regulated by
the cardiac center in the medulla oblongata
294
autonomic nervous system doesnt initiate
heart beat, but it does modulate the heart rate (speeds up/slows down)
295
impulses transmitted along sympathetic cardiac accelerator nerves release
norepinephrine, which binds to adrenergic receptors to increase heart rate and exert positive chronotropic effect
296
norepinephrine enhances
calcium entry into contractile cells causing them to contract w/ more force
297
impulses transmitted along vagus nerve
to heart releases acetylcholine which binds to cholinergic receptors to decrease heart rate and exert negative chronotropic effect
298
acetylcholine
hyperpolarizes membrane
299
cardiac center receives input from
the cerebral cortex, limbic system, hypothalamus, and from various receptors in order to regulate heart rate
300
proprioceptors
in muscles and joints detect changes in physical activity
301
baroreceptors
in aorta and carotid arteries monitor changes in blood pressure
302
chemoreceptors
in aorta, carotid arteries, medulla oblongata monitor changes in blood pH, carbon dioxide, oxygen
303
certain chemicals in the body have
chronotropic effects on heart rate
304
epinephrine and norepinephrine increase
heart rate
305
caffeine and nicotine increase
heart rate
306
calcium prolongs the
plateau of a cardiac muscle action potential
307
potassium reduces
the strength of a cardiac muscle action potential by making myocardium less excitable
308
congenital defects are
present at birth
309
most common birth defects in US
with 30,000 infants born each year w/one or more due to environmental influences, maternal infections, maternal drug use during second month of pregnancy
310
coarctation of the aorta
involve holes in the interatrial or interventricular septum
311
tetralogy of fallot (cluster of 4 defects)
1. interventricular septal defect
2. aorta
3. stenosis
4. right ventricle
312
interventricular septal defect
lets oxygen poor blood travel from right ventricle to left ventricle and into systemic circulation
313
aorta emerges
from both ventricles, which reduces cardiopulmonary circulation
314
stenosis
narrowing of pulmonary valve, reduces cardiopulmoanry circulation (less blood sent from heart to lungs)
315
right ventricle is enlarged
heart has to work harder
316
rheumatic fever
is caused by bacterial infection such as strep, that triggers the immune system to produce antibodies that can damage the bicuspid valve and aortic valves
317
cardiac tamponade
occurs if the pericardial cavity fills with fluid and compresses
318
cardiomyopathy
refers to any disease that results in deterioration of the heart wall or abnormal thickening of the interventricular septum
319
valvular insufficiency refers to
any valve disorder that may lead to a heart murmur
320
aortic stenosis
results from narrowing aortic valve
321
mitral valve prolapse
occurs when a portion of mitral valve is pushed back into left atrium during ventricular systole
322
heart attack or myocardial infarction
involves the sudden death of heart muscle and its replacement with scar tissue because of ischemia
323
(heart attack 1) blood supply of an area of
the heart wall is interrupted
324
(heart attack 2) plaque is deposited
along wall of coronary artery
325
(h.a. 3) platelets
aggregate and release chemicals that trigger vasospasm
326
(h.a. 4) coagulation
common pathway of coagulation is activated
327
(h.a. 5) coronary artery
gets occluded by a clot and blood flow decreases
328
(h.a. 6) permanent damage to the heart if
blood flow to myocardium decreases for 2-4 hours, death of myocardium can occur within 6 hours
329
angina pectoris
is severe pain or tightness or pressure in the chest that accompanies ischemia of the myocardium (no death in cells or change in ESR)
330
pain in angina pectoris
is described as constricting, squeezing, chocking, or knife like; because anaerobic respiration in cardiac muscle cells produces lactic acid
331
treatment of angina pectoris
nitroglycerin; because it is a potent vasodilator that can improve blood flow to myocardium
332
congestive heart failure
results from the failure of ventricles to pump blood effectively
333
consequences of congestive heart failure
blood backs up in the lungs, causing pulmonary edema or blood backs up in the systemic vessels causing peripheral edema
334
SA node establishes
the typical sinus rhythm of ones heart
335
ectopic focus
spontaneous generation of action potentials outside of SA node
336
arrythmia
is any abnormal or irregular heart beat due to the faulty production of electrical impulses or the poor conduction of impulses through the heart
337
if the SA node becomes diseased or damaged and fails to set the sinus rhythm
the AV node can take over and establish a nodal rhythm at a much slower rate
338
AV node produces only
40 to 50 beats per minute (if it takes over for the SA node) instead of the usual 70 to 80 bpm
339
artificial pacemaker
can be implanted under skin to electrically stimulate ventricles to contract
340
heart block
is the failure of the cardiac conduction system to transmit signals along the right and left bundle branches, which results in missed heart beats or reduced heart rate
341
bradycardia
is a resting heart rate of less than 60 beats per minute
342
atrioventricular block
involves prolonged or intermittent or missing conduction of nerve signals
343
total heart block
damages AV node and reduces ventricular contractions to between 20 & 40 bpm
344
atrial flutter
ectopic foci in the atria cause atrial rhythm to reach 240 to 360 bpm
345
tachycardia
is a resting heart rate in excess of 100bpm
346
premature ventricular contractions
occur when action potentials are initiated independent of the SA node and cause occasional abnormal heartbeats
347
extrasystole
occurs because the impulse is generated more quickly from the SA node and the heart has a longer time for ventricular filling
348
premature ventricular contractions/extrasystole can be triggered
if the heart is irritated by certain drugs or by lack of sleep or by stress
349
ventricular fibrillation
is a life threatening condition caused by nerve signals arriving at different parts of the myocardium at different times
350
consequences of ventricular fibrillation
blood is not pumped so blood does not flow to the myocardium and an MI (heart attack) occurs
351
defibrillation
strong, brief electric defibrillation depolarizes the entire heart so the SA node can resume normal rhythm
