lesson 12 Flashcards
During the early phases of development, the embryo is nourished through ___ ___ _ ___ secreted by the uterine glands into the uterine cavity.
diffusion from the fluid ;
However, as the size and complexity of the
embryo increases it soon needs a ____ ____
it soon needs a circulatory
system
The __ __ including the heart, arteries, veins, and blood begins to
develop as early as the __ ___ to meet the embryo’s needs.
The circulatory system ; third week of
gestation
the first functional organ system.
circulatory system
The formation of blood cells, called _____ ,
occurs in ____ overlapping periods.
hematopoiesis: three overlapping periods
First period is called in formation of blood cells?
mesoblastic period
Mesoblastic period occurs where?
The Yolk sac
Second period is called ____ in blood formation and these 2 organs in this period are the major blood-forming organs. What are those?
hepato-lienal period; liver and the spleen
Third period is called ____ in blood formation and the major organ in blood formation here is what?
medullary period; bone marrow
In the mesoblastic period, the first blood cells appear in the ___ ___ ___ ___ very early in development.
visceral
mesoderm of the yolk-sac wall
At first in mesoblastic period, __ __ are formed, these are spaces in the mesoderm occupied
with clusters of haemangioblasts.
blood islands
In the mesoblastic period, Outer cells
differentiate
into ____, forming endothelial cells,
and the inner cells into primitive __ __
angioblasts; primitive blood cells
In the mesoblastic period, Blood islands are spaces in the mesoderm occupied by clusters of _____?
Haemangioblasts
The blood islands coalesce (come together) and the
____ ____ form ___ establishing
the first vessels.
endothelial cells; tubes
In the mesoblastic period, what is established when coalesce of blood islands happen along with endothelial cells creating tubes?
The first vessels
vasculogenesis is the process of spontaneous ____ ____ formation.
blood
vessel formation
This process of spontaneous blood
vessel formation is referred to as
vasculogenesis
Vessels form new vessels by sprouting
a process referred to as
angiogenesis
In mesoblastic period, The first blood cells to be formed are ?
primitive nucleated erythrocytes
In mesoblastic period, Primitive _____ evolves within a few days into ____ ____ resulting in erythrocytes without nuclei.
Primitive erythropoiesis; mature erythropoiesis
Erythrocytes without nuclei is made or created when primitive erythropoiesis is evolved into ____ ____
mature erythropoiesis
In hepatolineal period, this specific period in blood formation starts at a crown rump length of __ mm in cattle
8 mm
In the liver, in hepato lineal period, these two are seen.
erythropoietic stem cells as well as megakaryocytes
In the ___, erythropoietic stem cells and megakaryocytes can be seen.
By __ mm, neutrophils are also formed.
liver; 12 mm
neutrophils are seen to be formed in what period?
hepato-lineal period
In hepato-lineal period, the ___ becomes the most prominent hematopoietic organ in cattle embryos, up to the 5th month of pregnancy.
liver
In hepato-lineal period, what month does the liver’s blood forming activity declines and at birth it has ceased?
6 month
The liver is the most prominent hematopoietic organ in what animal embryo? And in up to how many months in pregnancy does this occur?
cattle embryos, 5th month of pregnancy/gestation
In hepato-lineal period, this organ is active in hematopoiesis from the third to ___ month of cattle pregnancy.
spleen; seventh (7th)
During the sixth month, in hepato-lineal period, the liver’s blood
forming activity _____ and at birth what will happens?
declines, ceased (stop)
In the medullary period, __ __ begins its
hematopoietic activity at a crown-rump
length of about __cm during the 4th
month of pregnancy in cattle.
bone marrow; 18 cm
In the heart, it develops from the horseshoe shaped ___ ___ after embryonic folding.
cardiac tube
Moreover, within what cavity of the embryonic disc did the cardiac tube got repositioned?
within the pericardial
cavity
Embryonic heart beats begin at:
Day 22 of pregnancy in the –
Day 23 in the – and –
Day 24 in the —
pig;
dog & cattle;
horse
In loop formation, the cardiac tube will become this type of shape, with the loop of pointing what way?
U-shaped; pointing ventrally
The cardiac tube
undergoes first a __ ___and then an internal division.
Loop formation
In the developing heart, the sinus venosus and atrium are initially not enclosed within the _________ but gradually become enveloped by it.
pericardium
The curved portion of the _________ develops into the future left ventricle.
ventricle
The curved portion of the _________ develops into the future right ventricle.
bulbus cordis
What will the curved portion of the bulbus cordis eventually develop into?
right ventricle
Later, during loop formation, the atrium becomes positioned _________ to the ventricle.
dorsal
Identify the structure that sets the rhythm for the developing heart’s beat
sinus venosus
In the heart chamber, there are steps in formation of heart chamber. The first two are:
- Incorporation of the sinus venosus into the atrium
- Division of the atrioventricular channel
In the heart chamber, there are steps in formation of heart chamber.
The third step is:
Division of the atrium
In the heart chamber, there are steps in formation of heart chamber.
The 4th step is:
Division of the ventricle and the bulbus cordis
In the heart chamber, there are steps in formation of heart chamber.
The 5th step is:
Division of the conus cordis and truncus arteriosus.
Step 3: Division of the Atrium
Identify the structure that grows to divide the atrium into right and left components.
(Answer: septum primum)
What is the role of the endocardial cushions in the formation of heart chambers?
(Answer: They grow and fuse in the midline to form the septum intermedium, dividing the atrioventricular channel into right and left channels.)
Step 3: Division of the Atrium
Name the structure that develops to the left of the septum primum to assist in atrial division.
(Answer: septum secundum)
Step 5: Division of the Conus Cordis and Truncus Arteriosus
What structure separates the conus cordis and truncus arteriosus to ensure separate blood flow channels?
(Answer: aorticopulmonary septum)
Step 5: Division of the Conus Cordis and Truncus Arteriosus
The cushions in the conus cordis fuse with those of the truncus arteriosus to form the _________, which helps in dividing the blood flow into two channels.
(Answer: aorticopulmonary septum)
Step 3: Division of the Atrium
Before the closure of the ostium primum, programmed cell death forms the _________ in the septum primum.
(Answer: ostium secundum)
Step 3: Division of the Atrium
The septum primum grows to separate the atrium into right and left components, leaving a small opening called the _________.
(Answer: ostium primum)
Step 2: Division of the Atrioventricular Channel
In the atrioventricular channel, thickenings called _________ grow until they fuse in the midline, forming the septum intermedium.
(Answer: endocardial cushions)
Step 1: Incorporation of the Sinus Venosus into the Atrium
The incorporation of the _________ into the atrium is the first step in heart chamber formation. (Answer: sinus venosus)
(Answer: sinus venosus)
Step 2: Division of the Atrioventricular Channel
At the atrioventricular channel, the inner
cardiac wall develops anterior and posterior
thickenings, called -___ ___
the endocardial cushions
In Arterial system, when the pharyngeal or branchial arches
form, each arch receives its ____ and ___
own cranial
nerve and its own artery.
Aortic Arch Formation and Fate in Mammal:
In mammals, the _________ and _________ aortic arches are largely rudimentary, while the fifth arch may remain rudimentary or may not develop at all.
Answer: first, second
In the arterial system, When the pharyngeal or branchial arches
form, each arch receives its own cranial
nerve and its own artery.
This results in the formation of _ ______ between the dorsal
and ventral aortae on each side.
six arterial
arches (aortic arches)
The third aortic arch connects the common carotid artery to the _________.
(Answer: internal carotid artery)
Only the _________, _________, and _________ aortic arches form components of the developing circulatory system.
(Answer: third, fourth, sixth)
Formation of Arteries from the Aortic Arches:
The _________ aortic arch largely degenerates, with a small portion forming the ___ ___.
(Answer: first and maxillary artery)
The _________ aortic arch becomes the aortic arch on the left, while on the right, it forms the __ ___ artery.
(Answer: fourth; right subclavian artery)
Small portions of the _________ aortic arch develop into the ___ and _____ arteries.
(Answer: second; hyoid and stapedial arteries.)
: The __ aortic arch regresses on the right, but on the left, it forms the _________.
(Answer: 6th; pulmonary trunk)
During fetal development, the pulmonary trunk is connected to the aortic arch via the _________.
(Answer: ductus arteriosus)
Post-natal transformation of the ductus arteriosus:
After birth, the ductus arteriosus becomes a non-patent structure called the _________.
(Answer: ligamentum arteriosum)
BONUS FACT:
Before a baby is born, the fetus’s blood does not need to go to the lungs to get oxygenated (because all nutrients are provided by the placenta).
The ductus arteriosus is a hole that allows the blood to skip the circulation to the lungs
nothing hehe take this sign as a break.
Name the three major veins involved in early fetal circulation, carrying blood from the yolk sac, placenta, and body of the embryo.
(Answer: vitelline vein, umbilical veins, cardinal veins)
Identify the vein that transports oxygenated blood from the placenta to the embryo.
(Answer: umbilical vein)
What vein carries blood from the yolk sac to the developing embryo?
(Answer: vitelline vein)
The common cardinal vein, cranial cardinal vein, and caudal cardinal vein are part of the developing _________ system.
(Answer: venous)
The _________ vein carries blood from the placenta and provides the embryo with oxygen-rich blood.
(Answer: umbilical)
In fetal circulation, blood from the left umbilical vein passes through the _________ venosus to mix with deoxygenated blood in the caudal vena cava.
Answer: ductus
Most of the oxygenated blood in the right atrium passes through the _________ ovale into the left atrium.
(Answer: foramen)
The _________ ovale permits blood to bypass pulmonary circulation by passing from the right atrium to the left atrium.
Answer: foramen
What structure allows blood to bypass the liver and flow directly into the caudal vena cava?
(Answer: ductus venosus)
What respiratory center is stimulated to initiate breathing after birth due to increased carbon dioxide tension?
(Answer: medulla oblongata)
Name the structure that closes as a result of increased pressure in the left atrium after birth.
(Answer: foramen ovale)
Which fetal structure allows relatively oxygenated blood to bypass the lungs and flow from the pulmonary trunk into the aorta?
Answer: ductus arteriosus
The _________ arteries carry blood back to the placenta for oxygenation.
(Answer: umbilical)
After birth, the closure of which structure prevents blood from the pulmonary trunk from entering the aorta?
(Answer: ductus arteriosus)
The first breath expands lung volume and increases blood flow to the lungs, raising pressure in the left atrium and closing the _________ ovale.
(Answer: foramen)
The contraction of the _________ venosus and left umbilical vein stops blood flow from the placenta to the newborn.
(Answer: ductus)
The _________ arteries contract to stop blood flow to the placenta.
(Answer: umbilical)
What structure forms from the cranial portions of the dorsal aortae in the embryo?
(Answer: internal carotid arteries)
Which vein carries blood from the cranial portion of the developing embryo?
(Answer: cranial cardinal vein)
Which vein is responsible for carrying blood from the caudal portion of the developing embryo
Answer: caudal cardinal vein)
The common cardinal vein receives blood from both the _________ and _________ cardinal veins.
(Answer: cranial, caudal)
Name the structure that receives oxygenated blood in the ductus venosus and deoxygenated blood from the liver and digestive tract.
(Answer: caudal vena cava)
Which chamber of the fetal heart receives mixed oxygenated and deoxygenated blood from the caudal vena cava?
(Answer: right atrium)
Which vein brings relatively oxygenated blood to the fetus, bypassing the liver through the ductus venosus?
(Answer: left umbilical vein)
The ductus venosus allows blood to bypass the _________ and flow directly to the caudal vena cava.
(Answer: liver)
Oxygenated blood from the placenta enters the fetal heart through the _________ vein and flows towards the liver.
(Answer: umbilical)
What structure remains as the ligamentum arteriosum after birth, previously allowing blood to bypass the lungs?
(Answer: ductus arteriosus)
Upon birth, the increased _________ tension triggers the respiratory center in the medulla oblongata, leading to the newborn’s first breath.
(Answer: carbon dioxide)
In the venous system
Three major veins can be distinguished:
the ______ or vitelline
veins carrying blood from the yolk sac
the ___ veins carrying blood
from the placenta
the ____ veins carrying blood from
the body of the developing embryo
omphalomesenteric
umbilical veins
cardinal veins
In circulation at birth
It terminates the fetal-maternal
association through the placenta.
Birth
