test 2 lecture 15 heart and vascular Flashcards
1
Q
Circulatory system includes ___
A
heart, arteries, veins, & blood
2
Q
___ develops when embryo grows too large for diffusion to supply its cells.
A
circulatory system
3
Q
___ is the 1st function organ system to form
A
circulatory system
ØIn dog, heart tubes fuse at ~4mm (day 18); septation largely complete by ~12mm (day 25)
4
Q
___ forms an arc around the anterior end of the neural plate which is full of ___ cell clusters
A
cardiogenic field
angiogenic
5
Q
Angiogenic cell clusters form the ___
A
cardiac crescent
6
Q
1.Hollow angiogenic cell clusters form in ___
A
cardiogenic field
7
Q
cardiogenic field coalesce into a ___ lined by endothelial cells
A
crescentic endocardial tube
8
Q
Cardiac tube (crescent) develops ___ and ___ layers
A
myocardial & epicardial layers
9
Q
as the embryonic disc folds how does the “heart move”
A
starts at cranial end
Brings heart caudal to head, below the foregut and in front of the transverse septum (the ventral part of future diaphragm, between the heart & liver)
Flips cardiac crescent back to front and brings it to a position below the dorsal aortae
10
Q
what happens to cardiac tube during development
A
‘Head tuck’ folding
reorients the cardiac tube so that the crescent arms point cranially
brings the heart below the foregut
Folding brings cardiac crescent (tube) ventral to dorsal aortae and the foregut
Crescent arms become the ventral aortae, which carry blood away from heart
Ends of ventral & dorsal aortae grow toward each other & eventually join
11
Q
Folding brings cardiac crescent (tube) ___ to dorsal aortae and the foregut
A
ventral
12
Q
Crescent arms become the ___, which carry blood away from heart
A
ventral aortae
13
Q
Ends of ventral & dorsal aortae grow toward each other & eventually __
A
join
14
Q
First (most cranial) aortic arch is formed when left & right dorsal & ventral ___ fuse
A
aortae
Aortic arches are paired. Left & right aortic arches connect left (or right) right dorsal aortae to left (or right) ventral aortae
15
Q
Left & right vitelline veins fuse with the caudal end of the ___
A
cardiac crescent
16
Q
fusion of vitelline veins form right & left horns of the ___, the heart’s venous inlet
A
sinus venosus
17
Q
sinus venosus
A
This is where blood from the body returns to the heart
18
Q
The umbilical and cardinal veins will later drain into the ___
A
sinus horns
19
Q
1st aortic arch
A
fusion of dorsal aortae and ventral aortae
20
Q
embryo folding laterally will do what for heart formation
A
brings left & right arms of cardiac crescent into contact
then Apoptosis removes walls between left and right arms of cardiac tube/crescent, forming unpaired midline heart tube
midline heart tube has endocardium, myocardium and epicardium
21
Q
cardiac midline tube is ___ to the primitive gut
A
ventral
22
Q
A
23
Q
Primary heart field forms
A
primordial ventricle
24
Q
Secondary heart field forms
A
primordial atria, right ventricle, bases of pulmonary trunk and aorta
25
cardiac neural crest forms
truncus arteriosus (outflow)
26
embroyonic veins flow into \_\_\_
sinus venosus
27
5 zones of midline heart tube during development
sinus venosus, atrium, ventricle, bulbus cordis, and truncus arteriosus
28
Multiple input vessels enter ___ at caudal end of\_\_\_
sinus venosus
atrium
29
\_\_ = outflow tract. Delivers blood to ventral aortae via \_\_at cranial end of heart tube
Bulbus cordis
truncus arteriosus
30
looping of heart tube
Folding wraps **atria** around outflow tract (**bulbus cordis + truncus arteriosus)**
31
Aortic arches carry blood from ___ (outflow tract) to dorsal aortae.
ventral aortae
32
The \_\_\_contributes to the ventral part of the diaphragm
septum transversum
33
folding of the heart loop happens where
primordial ventricle & bulbus cordis meet
34
compartmentalization of the heart happens in 3 processes
1. Atrio-ventricular separation
2. Atrial septation
3. Ventricular septation
35
What does compartmentalization do at a physiologic level
partitioning (separating atrium from ventricle, & dividing primordial atrium & ventricle) creates the heart architecture that keeps oxygenated blood (to body) **_separate from_** deoxygenated blood (to lungs)
36
Atrio-venticular separation
Developing **endocardial cushions** form the A-V septum that separates primordial atrium from ventricle & bulbus cordis,
will leave space on right and left for the AV valves to form
37
atrial septation
* Primary septum (blue) divides atrium
* Transient primary osteum is located between primary septum & endocardial cushions. (closes when septum meets cushions)
* Apoptosis fenestrates primary septum dorsally (forming secondary osteum) (at 30-32 days gestation in horse)
* Secondary septum (green) forms in right atrium (does not close ventrally)
* Endocardial cushions fuse to completed primary A-V septum
* 2 openings retained in A-V septum (future A-V valves)
* Secondary septum overlaps secondary osteum, but doesn’t fuse with A-V septum
* 1st & 2nd septae don’t fuse. Blood from fetal right atrium can flow into left atrium
* Passage through wall = foramen ovale. Pushed open (by blood flow) in fetal heart.
* Primary septum acts as valve to prevent backflow from left atrium to right atrium
38
what is the name of the hole in the primary septum that forms after the primary septum fuses with the endocardial cushion
foramen secundum
39
what is the name of the whole that is formed by the secondary septum
foramen ovale
40
blood circulation in heart in fetus
right artium → foramen ovale, foramen secundum → left atrium → left ventricle → out to body
41
\_\_\_ acts as valve to prevent backflow from left atrium to right atrium
Primary septum
42
1st & 2nd septae ___ fuse. Blood from fetal right atrium can flow into left atrium
don’t
43
Secondary septum overlaps secondary osteum, but ___ fuse with A-V septum
doesn’t
44
Cardiac end of right sinus horn is incorporated into the right atrium as the \_\_\_
sinus venarum
45
Ends of pulmonary veins are incorporated into the left atrium to become the main part of the\_\_\_
left atrium
46
The primordial atria become the ___ of the adult heart
_auricles_
47
Other sinus horn fates
Cardiac end of right sinus horn → into the right atrium as the sinus venarum
Anterior part of rt. sinus horn → cranial vena cava
Posterior part of right sinus horn → caudal vena cava
Left sinus horn → coronary sinus
48
Cardiac end of right sinus horn is incorporated into the right atrium as the \_\_\_\_
sinus venarum
49
Ends of ___ are incorporated into the left atrium to become the main part of the left atrium.
pulmonary veins
50
the right ventricle is formed from the \_\_\_
bulbus cordis
51
\_\_\_ grows upward from heart apex toward endocardial cushion
I-V septum
52
The bottom part of I-V septum is muscular. Top initially incomplete; opening is called the \_\_\_\_
interventricular foramen.
53
\_\_\_ is normally closed by growth of membranous upper part of interventricular septum
Interventricular foramen
54
EC= endocardial cushion
55
IAS= interatrial septum
56
right sinus venosus
57
left= IVF= interventricular foramen
IVS= interventricular septum
58
AA= ascending aorta
PT= pulmonary trunk
SS= spiral septum
59
AA = ascending aorta
DucA = ductus arteriosus
LDA = left dorsal aorta
PT = pulmonary trunk
60
IV septum divides what into what
bulbus cordis and left ventricle
right and left ventricle
61
spaces next to endocardial cushion is __ and will become \_\_
AV orifices
right and left mitral valves
62
bulbus cordis turns into
right ventricle and ascending aorta and pulmonary trunk
63
Bulbar ridges and truncal ridges grow inward from the walls of the \_\_\_
bulbus cordis & truncus arteriosus
64
\_\_\_ and ___ form the spiral septum
bulbus cordis→bulbar cushion → bulbar septum
truncus arteriosus→ truncal cushion → truncal septum
aortic sac→ aortic cushion?? → aortic-pulmonary septum
65
The ___ ridges unite to form the spiral septum
bulbar and truncal
66
the spiral septum divides outflow tract into ___ and \_\_\_
aorta & pulmonary trunk
67
Outflow tract division completes separation of the ___ and ___ loops
oxygenated & deoxygenated
68
what holds the aorta and pulmonary artery together
ligamentum arteriosum
69
Truncus arteriosis comes from \_\_\_
cardiac neural crest
70
Bulbus cordis (from \_\_\_) develops into the right ventricle and part of the spiral septum
secondary heart field
71
The primordial ventricle (from \_\_\_) becomes the left ventricle
primary heart field
72
Outflow tract division (into aorta & pulmonary trunk) happens _at the same time_ as \_\_\_
ventricular septation
73
\_\_\_is involved in outflow tract formation, and its division.
Neural crest
74
Outflow tract (aorticopulmonary) septum and \_\_\_**must** **line up correctly**. why?
interventricular septum
if RV and pulmonary trunk, and LV and aorta do not line up correctly then deoxygenated and oxygenated blood can mix or one vessel will be smaller then the other and will not be strong enough to do its job
75
Right ventricle must open to \_\_\_; left ventricle must open to \_\_.
pulmonary trunk
aorta
76
Failure of septae to line up leads to cardiac malformations (example: \_\_).
Teratology of Fallot\*
## Footnote
Teratology of Fallot: large defect in IV septum; aorta overrides both ventricles; pulmonary stenosis; enlarged right ventricle
(high pressure in right ventricle pushes deoxygenated blood through septal defect into left ventricle to mix with oxygenated blood to aorta)
77
Teratology of Fallot:
large defect in IV septum; aorta overrides both ventricles; pulmonary stenosis; enlarged right ventricle
(high pressure in right ventricle pushes deoxygenated blood through septal defect into left ventricle to mix with oxygenated blood to aorta)
78
\_\_\_= most common congenital malformation in domestic animals.
Cardiac malformations
79
heart has 4 valves:
2 AV valves (bicuspid)
2 semilunar (aortic and pulmonary) (tricuspid)
80
Valves prevent\_\_\_as it passes through heart and exits heart
backflow of blood
81
\_\_\_ are essential to normal heart function
Valves
82
how do AV valves form
formed by apoptosis, which sculpts the ventricular walls. Apoptosis leaves behind the **valve flap, cordae tendinae, and papillary muscles**
83
Normal A-V valves are closed by ___ to prevent backflow from ventricles to atria
ventricular pressure
84
what do chordae tendineae do?
prevent AV valves from flapping up into the atrium
85
The AV valves are made from
remnants of myocardial cushion
and apoptosis of ventricular walls
86
\_\_: have 3 ~triangular cusps, each with a nodule in the center of its free edge that helps seal the valve shut
Semilunar valves
87
Semilunar valve cusps start as ___ that grow inward from the walls of the aorta or pulmonary trunk
mesenchymal swellings
88
Three swellings form at each valve location. Each swelling will become a valve cusp.
what type of valve?
Tricuspid/semilunar
89
\_\_\_ sculpts the swellings into thin, flexible flaps that form the 3 cusps of each semilunar valve
Apoptosis
90
what stops back flow in semilunar valves?
valve cusp lining up correctly create one way valve
91
the SA node is formed where
the sinus venosus and primordial atrium met
92
how does heart pump
SA node (sinoatrial) starts contraction
travels to AV node (atrioventricular) which delays signal
waits for atrium to contract then sends signal down bundle of his through purkinje fibers to make ventricle contract
93
•The \_\_(pacemaker) initiates contraction
SA Node
94
Impulse travels from the SA node through atrial walls to the \_\_\_
AV Node
95
AV Node __ impulse (so that ventricles contract __ atria)
delays
after
96
AV Bundle transmits impulse to ___ network in ventricle walls. (Coordinates ventricular contraction)
Purkinje fiber
97
purkinje fibers make the ventricle contract \_\_\_
apex to base (bottom to top) push blood up
98
\_\_\_ develops very early in development and acts as pacemaker
SA node
99
blood cell formation begins \_\_\_
in the yolk sac
100
\_\_clusters in yolk-sac mesoderm coalesce to form vessels
Haemangioblast
101
Outer cells differentiate into angioblasts that form vessel walls (\_\_\_)
vasculogenesis
102
vasculogenesis
Outer cells differentiate into angioblasts that form vessel walls
103
Outer cells differentiate into \_\_\_that form vessel walls
angioblasts
104
Haemangioblast clusters : Inner cells differentiate into \_\_\_
primitive blood cells
105
Earliest erythrocytes are \_\_\_; later erythrocytes lack nuclei
nucleated
106
Later endothelial cells are derived from \_\_\_, which give rise to ___ that make adult blood cells
embryonic mesoderm
Haematopoietic Stem Cells (HSCs)
107
Site of blood cell formation changes during development
**Mesoblastic stage** – blood cells form in the yolk sac
**Hepato-lienal period** – blood formation in liver, then spleen. Begins in approx. 8mm embryo (in the ox), & fully active at 18mm
**Medullary** – blood formation in bone marrow. Begins at ~18cm in the ox.
**By birth** hematopoiesis is confined to the bone marrow
108
\_\_\_ is when blood cells form in the yolk sac
Mesoblastic stage
109
\_\_ is when blood formation in liver, then spleen. Begins in approx. 8mm embryo (in the ox), & fully active at 18mm
Hepato-lienal period
110
\_\_ is when blood formation in bone marrow. Begins at ~18cm in the ox.
medullary
111
By birth hematopoiesis is confined to the \_\_\_
bone marrow
112
blood cell formation mesoblastic stage
113
the embryo has 3 circulatory loops
body
vitelline
allantoic(umbilical)
114
of the 3 embryo circulations: vitelline, allantoic and body which remain in adult?
body
115
Vascular endothelium has 2 sources: ___ & ___ from yolk sac.
embryonic mesoderm
erythro-myeloid progenitors (EMPs)
116
Proportion of (erythro-myeloid progenitors) EMP-derived cells in vessel walls varies between organs, ranging from __ in brain to \_\_\_in liver
30%
60%
117
Early development: no ___ yet. Blood flow = artery to intercellular space to vein.
capillaries
118
Embryonic ‘body’ loop is divided into 2 pathways in the fetus & adult: one to lungs (to oxygenate blood) and one to body (to distribute O2 & nutrients; and to \_\_\_)
collect wastes)
119
Primitively, __ aortic arches connect the dorsal & ventral aortae.
6
120
ventral aortae will turn into
common (caudal part) & external (cranial part) carotid
121
The dorsal aortae will turn into
internal carotid aa. (cranial part) & aorta (caudal part)
122
3rd aortic arch will \_\_\_
connects common carotid to internal carotid (not in ruminant, cat)
123
4th aortic arch will turn into
aorta (on left side), or subclavian artery (on right side)
124
6th aortic arch turns into
**on the left side**: pulmonary trunk (& ductus arteriosus)
**on right side:** 6th arch regresse
125
which aortic arches remain and which degenerate
3, 4 and left side of 6
1, 2, 5 and right side of 6
126
during development of aortic arches what is formed to divide them
pharyngeal pouches
127
In the embryo, the body is drained by \_\_
cardinal, subcardinal, & supracardinal veins
128
Adult veins are derived mainly from the ___ veins
subcardinal
with small contributions from the other veins (cardinal and supracardinal)
129
Vitelline veins become
Sinusoids of liver
Part of caudal vena cava
(e.g. hepatic & hepatocardiac parts)
Hepatic portal vein
130
Umbilical veins regress:
* Right – **regresses in fetus**
* Left – **closes at birth** (failure to close (patent ductus venosus) can produce pathologies (examples: hepatic encephalopathy, disuria, polyuria
131
patent ductus venosus
failure to close left umbilical vein
## Footnote
produce pathologies (examples: hepatic encephalopathy, disuria, polyuria)
132
Development of the heart begins in the \_\_\_, a horseshoe-shaped region of visceral mesoderm which forms an arc around the anterior end of the neural plate.
cardiogenic field
133
“Head tuck” folding of the embryo repositions the cardiac tube ventral to the embryonic disc and ___ to the embryo’s head
caudal
134
head tuck folding also reverses the orientation of the cardiac crescent so that the arms of the crescent – which will become the ventral aortae – point ___ instead of \_\_
forward (toward the embryo’s head)
caudally
135
Lateral folding of the embryo brings the edges of the embryonic disc together ___ of the embryonic disc.
ventral to the midline
136
The caudal portions of the left and right ventral aortae (the caudal part of the cardiac crescent) are brought into contact; these tubes are fused into a single midline heart tube as \_\_\_removes the walls that separate the left and right sides of the cardiac crescent from each other.
apoptosis
137
\_\_\_ fuse with the caudal arch of the cardiac crescent to form the inlet of the heart; slightly later other veins (umbilical and cardinal veins) also connect to the caudal (input) end of the heart tube.
Vitelline veins
138
The unpaired midline heart tube that was formed by fusion of the left and right limbs of the cardiac crescent plus fusion with the vitelline veins now begins pumping blood out into the ventral aortae at its \_\_\_end.
cranial (output)
139
The simple heart tube is suspended in the pericardial cavity by a dorsal mesocardium; and is initially anchored by a \_\_\_. what happens to the this structure?
ventral mesocardium
transient structure, goes away
140
the heart tube chambers from posterior to anterior
the sinus venosus; the atrium; the ventricle; the bulbus cordis; and the truncus arteriosus
141
The truncus arteriosus is formed by \_\_\_
cardiac neural crest cells.
142
looping of the heart happens at where \_\_\_
where the primordial ventricle meets the bulbus cordis.
143
Walls of the primordial ventricle (future left ventricle) and the part of the ___ that will become the right ventricle become thicker and \_\_\_as the heart grows.
bulbus cordis
trabeculated
144
The opening between the bottom of this septum and the endocardial cushions, the \_\_\_, is eventually closed when the primary septum meets the endocardial cushions.
primary osteum
145
As the primary osteum closes apoptosis creates a ___ near the top of the primary septum
secondary osteum
146
After the septum primum has formed secondary osteum, a second, thicker fold of tissue (\_\_\_) grows downward just to the __ of the septum primum. The secondary septum extends downward far enough to cover the right side of the secondary osteum, but a gap (\_\_) between the two septae remains patent in the __ atrium.
the septum secundum
right
the foramen ovale
right
147
\_\_\_ allow blood to flow from the right atrium to the left atrium.
foramen ovale in the septum secundum
secondary osteum in the septum primum
148
The ventral part of the thinner ___ acts as a valve to keep blood from flowing back into the right atrium and ensure unidirectional blood flow through the foramen ovale and into the left atrium.
primary septum
149
As the fetus grows and the fetal heart handles more blood, the right atrium grows by incorporating the ___ into the right atrium
right horn of the sinus venosus
150
Initially all of the blood returning to the heart from the developing lungs enters the left atrium through a single common \_\_\_. This common venous trunk later is incorporated into the \_\_\_, and forms the smooth-walled main portion of the left atrium.
pulmonary vein
developing left atrium
151
single common pulmonary vein develops into \_\_
4 individual veins
152
At first there is an opening (\_\_\_) between the top of the muscular interventricular septum and the endocardial cushions.
an interventricular foramen
153
Growth of the ___ is accompanied by thickening and trabeculation of the walls of the primordial ventricle (the adult left ventricle) and proximal bulbus cordis, which will become the adult right ventricle.
interventricular septum
154
Division of the heart into four chambers has great physiologic significance. It allows the separation of ___ and ___ blood into two separate circulatory loops – the pulmonary and body systems of the adult animal.
oxygenated and de-oxygenated
155
At first both the left and right ventricles empty into the bulbus cordis, and blood from both ventricles flows into the undivided \_\_\_
truncus arteriosus
156
Complete separation of oxygenated and deoxygenated blood requires that the bulbus cordis and truncus arteriosus also be divided. Division of these structures is accomplished by the bulbar ridges, which grow inward from the bulbar walls and meet to form the \_\_\_
spiral septum
157
\_\_\_ separates outflow from the right ventricle (to the pulmonary trunk) and outflow from the left ventricle (to the aorta)
the spiral septum
158
\_\_\_ cells contribute significantly to formation of the bulbar ridges, semilunar valves, and to the walls of the proximal parts of the coronary arteries.
Cardiac neural crest
159
Myocardial cells are replaced by connective tissue in the \_\_\_; the papillary muscles remain muscular.
cordae tendinae
160
The semilunar valves begin their development as swellings at the outlet of the ___ into the ventral aortae
truncus arteriosus
161
Clusters of haemangioblasts (blood islands) form in the yolk sac mesoderm. The outer cells in these clusters will become \_\_\_, which form endothelial cells. The inner cells will become \_\_\_.
angioblasts
primordial blood cells
162
The blood islands coalesce into larger elongate structures, and their outer endothelial cells form the first ___ (which are located in the yolk sac).
blood vessels
163
Spontaneous formation of blood vessels is called \_\_\_. These first-formed vessels later grow side branches, a process which is called\_\_\_.
vasculogenesis
angiogenesis
164
The embryo has three circulatory loops
1) the vitelline loop, which supplies the yolk sac
2) the umbilical loop, which connects to the placenta for gas and nutrient exchange
3) the body loop.
165
The body loop of the embryo gives rise to the two definitive circulatory loops of the fetus and adult: \_\_
the pulmonary and systemic loops.
166
The aortic arches develop in a ___ direction as the embryo grows, meaning that the 1st aortic arch is the most cranial, and the 6th aortic arch is the most caudal.
cranial-to-caudal
Not all of them are present in a mammalian embryo at any one time – arches that will be lost (like the 1st or 2nd arch) will degenerate before later arches like the 6th aortic arch begin to form.
167
The ventral aortae of the embryo become \_\_
the common carotid and external carotid arteries of the adult animal.
168
The cranial portions of the dorsal aortae (i.e. the parts that lie cranial to the 3rd aortic arch) will become the \_\_
internal carotid arteries of the adult
169
The 3rd aortic arch will be retained (in some species) as the extracranial part of the \_\_\_. In other species (e.g. the ox or cat) this extracranial segment of the future internal carotid artery degenerates *in utero*, and is not present in the adult animal.
internal carotid artery that connects to the common carotid artery
170
The left 4th aortic arch becomes the ___ of the adult mammal; on the right side the 4th aortic arch becomes the \_\_\_
ascending aorta
right subclavian artery
171
The 6th aortic arch connects to the right ventricle and the left side becomes the \_\_\_. The right side \_\_\_
pulmonary circuit
pulmonary artery – and its distal end, which is still connected to the aorta (= the dorsal aorta of the embryo) becomes the **ductus arteriosus** of the fetus (which allows blood to bypass the developing lungs). This distal part of the left 6th aortic arch closes at birth to become the **ligamentum arteriosum** of the adult.
regresses
172
**left side of the 6 th aortic arch** becomes pulmonary artery – and its distal end, which is still connected to the aorta (= the dorsal aorta of the embryo) becomes the ___ of the fetus (which allows blood to bypass the developing lungs). This distal part of the left 6th aortic arch closes at birth to become the ___ of the adult.
ductus arteriosus
ligamentum arteriosum
173
Segmental arteries of the embryo branch from the \_\_. Dorsal segmental arteries will supply the __ and \_\_
dorsal aortae
body wall and neural tube
174
Lateral segmental arteries supply the \_\_\_
organs developed from intermediate mesoderm (like the kidneys and reproductive tract organs).
175
Ventral segmental arteries will become the \_\_\_
celiac; cranial, and caudal mesenteric; and umbilical arteries.
176
The embryo has three major veins: ___ (which drain the yolk sac), ___ (returning blood from the placenta), and ___ (which drain the body).
vitelline veins
umbilical veins
cardinal veins
177
The vitelline veins will ultimately become the ___ of the liver (the cranial parts of the vitelline veins); the ___ segment of the caudal vena cava (the cranialmost part of the right vitelline vein); and the \_\_\_(the caudal part of the vitelline veins).
sinusoids
hepatocardinal
portal vein
178
The right umbilical vein largely \_\_\_, but its cranial end contributes to the sinusoids of the liver.
involutes
179
The left umbilical vein contributes to the \_\_\_, which allows most of the blood from the placenta to bypass the liver on its way to the heart.
ductus venosus,
180
1. The more caudal part of the left umbilical vein will involute after birth and become the \_\_\_of the liver.
round ligament
181
The body of the embryo is drained by a complex network of different types of “cardinal” (body-draining) veins. These are the \_\_\_, ___ and \_\_.
lateral cardinal
medial subcardinal
dorsal supracardinal veins
182
The cardinal and ___ veins anastomose with each other extensively.
subcardinal
183
The caudal vena cava is ultimately derived from ___ types of embryonic cardinal vein
all three
184
The pelvic part of the caudal vena cava develops from the ___ vein.
right supracardinal
185
the lumbar part of the caudal vena cave is formed by anastomosis of the __ and \_\_
subcardinal and cardinal veins
186
The abdominal part of the caudal vena cava is derived from the anastomosis of the ___ and \_\_\_
right subcardinal and vitelline veins.
187
The ___ vein is derived from cranial parts of the cardinal and supracardinal veins
azygous
188
Cardinal veins that are located cranial to the heart give rise to the ___ and \_\_\_
internal jugular and brachiocephalic veins.
189
The segment of the cranial vena cava that enters the heart is derived from the cranial part of the \_\_\_
right sinus venosus horn
190
The caudal vena cava is derived from the caudal part of the \_\_\_
right sinus venosus horn.
191
The ___ becomes the coronary sinus of the adult heart, and returns blood from the heart walls to the general circulation
left horn of the sinus venosus
192
In the fetus blood is oxygenated and CO2 is removed by the \_\_
placenta.
193
Oxygen-rich blood returns to the conceptus via the \_\_\_
umbilical veins.
194
In the early embryo, umbilical veins were paired. The part of the\_\_ umbilical vein between the umbilicus and the liver involutes early on in development; only the ___ umbilical vein remains functional in the fetus.
right
left
195
Most of the blood in the left umbilical vein bypasses the liver through the ___ but a small amount supplies the developing liver with oxygenated blood and nutrients.
ductus venosus,
196
\_\_\_ blood traveling through the ductus venosus mixes with ___ blood draining from the caudal body and digestive tract in the caudal vena cava. This mixed blood enters the right atrium, where it is mixed with more ___ blood from the cranial vena cava.
Oxygenated
deoxygenated
deoxygenated
197
Most of the blood that enters the right atrium gets shunted toward the left atrium through the \_\_\_
foramen ovale
198
Only a small amount of the somewhat oxygen-rich blood in the right atrium passes through the ___ into the right ventricle, and is then pumped out into the pulmonary trunk.
A-V valve
199
Most of the blood in the pulmonary trunk bypasses the lungs by flowing through the \_\_\_, which carries it directly to the aorta.
ductus arteriosus
200
The blood that entered the left atrium through the foramen ovale is joined by the small amount of ___ blood returning from the fetal lungs.
deoxygenated
201
Some of the blood in the aorta is returned to the placenta via the \_\_\_; the rest supplies body tissues and organs and is returned to the heart via the venous system.
umbilical arteries
202
At birth, the loss of __ supplied by the umbilical cord results in an increase in __ tension in the neonate
O2
CO2
203
The __ increase stimulates respiratory centers in the medulla, and triggers respiration.
CO2
204
The first breath expands the lungs, which in turn stimulates \_\_\_.
pulmonary circulation
205
The increase in blood flow to the lungs results in an increase in the volume of blood entering the left atrium through the pulmonary veins. This increased input increases pressure in the left atrium. The increased pressure pushes the thin primary septum against the thicker secondary septum, closing the \_\_\_
foramen ovale.
206
The closed foramen ovale remains visible as the ___ in the right atrium
fossa ovale
207
Reflexive constriction of the walls of the ___ stops oxygen-poor blood in the pulmonary trunk from flowing through the ___ and mixing with the oxygen-rich blood in the aorta
ductus arteriosus
ductus arteriosus
208
The lumen of the ductus arteriosus is obliterated, but the vessel walls of the ductus persist after birth as the \_\_\_.
ligamentum arteriosum
209
During birth, blood flow to the placenta is shut down by contraction of the umbilical arteries (which become the ___ ), and blood flow from the placenta is closed off by constriction of the ductus venosus and umbilical vein. The (left) umbilical vein persists after birth as the \_\_\_
round ligaments of the bladder
round ligament of the liver.
