Heart Development Flashcards
Pharyngeal arches contain
1.) Mesoderm
2.) Cartilage (to bone)
3.) Nerve
4.) Blood vessel
What is the purpose of heart development?
Creation of the mesoderm to primitive heart and vascular system
Establishment of vascular system
Timeline of heart development
1.) Primitive streak
2.) Mesodermal layer (trilaminar disc)
3.) Primary heart field (into lateral folds)
4.) 2 heart tubes
5.) Fused heart
6.) Formation of valves, etc.
During week _____, mesoderm and ________ ______ ___________ _____ travels through primitive streak toward the embryo’s _____ (day 16) and travel to the __________ mesoderm (which becomes the HEART)
3; primitive heart progenitor cells; head; splanchnic
During week 3, mesoderm also forms the _______ ________, these form in the cariogenic region and _____ to become a “horseshoe-shaped” mesoderm area with 2 limbs called the ________ ______ _____ or _______ _________ via vasculogenesis
Blood islands; fuse; Primary Cardiac Field or Cardiac Cresent
Vasculogenesis
form vessels that lead to two heart tubes aka the Secondary Cardiac Field
The RV (right ventricle) and outflow comes from the ______ cardiac crescent -> populates the pharynx before migrating to form the heart -> “_________ field” of cardiac precursor not part of early linear heart tube
medial; secondary
Week 3-4 (Day 19), _______ mesoderm splits into ________ and ________ layer
lateral; somatic and splanchnic
Week 3-4 (Day 19), when the body folds are growing ______ and fuse at the ventral midline the _________ - *VEGF signals to splanchnic mesoderm and thus the limb’s blood island cells to organize/specialize/differentiate into ___ endocardial tubes (mesoderm) AND pericardial cavities
laterally; Endoderm; 2
Week 3-4 (Day 21-22) Endoderm - VEGF influences _______ mesoderm and forms two ______ endocardial tubes
splanchnic; layered
2 layered endocardial tubes
1.) Angioblast
2.) Hemocytoblast
Angioblast
blood vessels -> heart tube -> endocardium
Hemocytoblast
blood cells
Week 3-4, concurrently, the embryonic coelom gives rise to ______ ________ ________ and forms ________ to each cardinal tube
primitive pericardial cavity; lateral
(week 3-4) Mesoderm cells also form a pair of longitudinal vessels called what?
Dorsal aorta
Layers of heart tube
1.) Endocardium
2.) Cardiac jelly secreted
3.) Myocardium
Heart develops ________ to _______
cranially; caudally
At first, the heart tube and pericardial coelom are ______, BUT when _____ folds, it pushes the heart (stuffs it) into the _________ cavity
separate; head; pericardial
- As the heart tube _____ the primordial myocardium forms from ________ mesoderm of the pericardial coelom
- The _______ (visceral pericardium) arise from the _____ surface of the _____ _______ and spreads on the myocardium
Fuse; splanchnic
Epicardium; external; sinus venosus
The heart tubes fuse into 1 and this tube will continue to __________
differentiate
Week 3, at ______ end, each endocardial tube connects to _________ ______ (x2) stemming from yolk sac
inferior; vitelline veins
Week 3/4, the embryo folds into a _________ shape as the lateral borders meet at ______ midline
cylindrical; ventral
(week 3-4) Two endocardial tube FUSE, becoming _______ ______ ____ with a single surrounding _________ ______
Left and right vitelline veins also FUSE to become _____ _______ (______ track)
Primitive Heart Tube; Pericardial Cavity
Sinus Venosus (inflow)
Ventral/visceral/splanchnic mesoderm becomes the _____
- it comes in contact with the endoderm
- there are inducible factors or signals VEGF between the endoderm and mesoderm and these form the heart, gut, etc.
heart
_______ closing and cardiac tubes moving closer together
foregut
Heart
fist sized cone-shaped involuntary muscle whose function is to contract/relax and segregate blood (O2/CO2) in order to circulate the blood throughout the body
Parts of the heart
- chambers
- valves and septa
- vessels
- membranes
- blood flow
Heart is located within _________ space between the lungs
mediastinum
Heart is surrounded by it’s own __________ cavity
pericardial
Heart is surrounded by it’s own __________
membranes
Chambers
muscular rooms in the heart that hold blood for a period of time before the blood is pushed out to vessels
4 chambers of the heart
2 upper atria
a.) Right and Left atria
- thin walled and a holding pool for blood
2 lower ventricles
b.) Right and left ventricles
- thick walled and push the blood to vessels
Valves
separate the chambers of the heart and direct blood flow (DRCT)
2 cuspid valves
separate the heart chambers (atria from ventricle)
1.) Tricuspid (atrioventricular) valve
2.) Bicuspid (atrioventricular) valve
Tricuspid valve
separates the R atrium from the R ventricle
Bicuspid valve
separates the L atrium from the L ventricle (aka Mitral valve)
2 semilunar valves
separate the ventricles from the outflow vessels
1.) Pulmonary Semilunar
2.) Aortic Semilunar
Pulmonary semilunar
lies between the R ventricle and the PULMONARY TRUNK
Aortic semilunar
lies between the L ventricle and the AORTA
Septa
Muscular wall separates R from L side of the heart
Vessels that empty into the R atrium
1.) Inferior vena cava
2.) Superior vena cava
Inferior vena cava
delivers LOW O2 blood from the lower body
Superior vena cava
delivers LOW O2 blood from the shoulders and head
Vessels that empty into the L atrium
Pulmonary veins
Pulmonary veins
coming from the lung carrying HIGH O2 blood
Vessels that empty out the R ventricle
Pulmonary trunk
Pulmonary trunk
bifurcates into the R and L Pulmonary Arteries carrying LOW O2 blood to the lung
Vessels that empty out the L ventricle
Aorta
Aorta
coming from the L ventricle that arches and splits into many arteries that carries high O2 blood to the entire body
Coronary
arteries and veins that feed the heart itself
Parietal pericardium
is a thick membranous sac surrounding the heart that secretes a small quantity of lubricating fluid (serous) (aka PERICARDIAL SAC)
What is the space called that is part of the heart wall and membranes?
Pericardial space
Visceral pericardium
is a thin membranous membrane lying on the surface of the heart (aka EPICARDIUM)
Endocardium
lines the inner surface of the heart chambers
Heart walls and membranes
- parietal pericardium
- pericardial space
- visceral pericardium
- endocardium
Endomysium
loose connective tissue between cell
Blood flow: superior and inferior vena cava carrying LOW O2 blood from the body
1.) blood enter the R atrium
2.) through the tricuspid valve
3.) into the R ventricle
4.) through the pulmonary semilunar valve
5.) into the R and L pulmonary arteries
6.) to the lung to be oxygenated
7.) High O2 blood flows into the R and L pulmonary veins
8.) into the L atrium
9.) through the bicuspid valve
10.) into the L ventricle
11.) through the aortic semilunar valve
(Blood enters the Aorta and branches off into the many arteries of the body)
Week 3: Dorsal aorta: the aorta _____ -> becoming the _____ ___ (outflow tract)
Primitive ______ cavities _____ -> becoming the pericardial cavity
Heart tube remains ___________ to the pericardial cavity via mesoderm sheet known as ________ _____________
FUSE; aortic sac
pericardial; fuse
attached; dorsal mesocardium
At week 3, heart tube now has TWO layers
1.) Endothelial lining
- endocardium
2.) Cardiac myoblasts
- myocardium
Folding of body pushes the primitive heart tube towards the ______
chest
Week 4, heart is at ______ and blood is pumping through heart
thorax
Week 4, Muscle Cells; some myocardial cells in _____ ______ begin to produce ________ ________ _________
sinus venosus; rhythmic electrical discharge
(week 4, muscle cells) Mesenchymal cells of the ______ __________ will proliferate and migrate over myocardium to become __________
dorsal mesocardium; epicardium
Embryonic heart muscle cells
the early heart pump has NEURAL INTEGRATION and starts to pump
cells differentiate very early -> CONTRACTILE CELLS (actin and myosin) of a differentiated cell can undergo cell divisions like an undifferentiated cell, and continues to grow at the same time
satellite cells repopulate muscle cells and replace muscle cells
diffusion of “nutrient” is not enough from cell to cell and at a certain point in development it is NOT enough to supply the embryo so…
- vessels//circulation are needed to deliver gases and nutrient to the embryo body
- this is why the heart develops so early
All circulatory systems have 3 parts
1.) Pumps (heart)
2.) Pipes (major and minor vessels)
3.) Fluid (blood/liquid/cells)
Overview of circulatory system
1.) All aspects of the circulatory system come from the mesodermal cell lineage
2.) The PUMP appears early in embryonic development and is often the 1st functional organ
3.) The pump and the pipes have DIFFERENT SPATIAL ORIGINS and are NOT initially connected
4.) The FLUID that fills the pipes also has a different origin
5.) All circulatory systems start out OPEN; some later close like humans
If NO closure/fusion of endocardial tubes (ventral portion) into one tube
Cardia bifida
(ventral portion) Neural tube is closing and the endocardial tubes are ______ and starting to ______
closing; contract
(The pump) ________ cells enter the body cavity in 2 streams:
mesodermal;
1.) somatic/parietal and lateral
2.) visceral/ventral/splanchnic
(The pump) the _______ mesoderm collects into a pair of hallow tubes that merge at the midline
ventral
(The pump) The fused tubes create a central, 2 layered vessel consisting of:
Endocardium
- inner lining of the chambers
Myocardium
- cardiac muscle cell
(The pump becomes specified) The conjoined cardiac tube expands to create a series of chambers (caudal to cranial)
a.) Sinus venosus (collects blood from body)
b.) Atrium (a little pumping station)
c.) Ventricle (bigger pumping station)
d.) Bulbus Cordis
e.) Truncus Arteriosus (the outlet port)
f.) Aortae (transfers blood to the body)
Heart looping and septation
1.) Rapidly dividing cells contort the tube into an S-SHAPE toward R side of the embryo
2.) The ventricular and atrial portions become DILATED
3.) ENDOCARDIAL CUSHIONS are seeded by MESENCHYMAL CELLS to separate the atria from ventricles
4.) MEMBRANOUS SEPTA divide the atria/ventricles into L and R sides
5.) VALVES eventually direct one-way blood flow
Looping steps
1.) Middle of the heart tube bends to R side due to increase cell division; asymmetry, and this influences development of future organs
2.) cell divisions also causes the ventricle and atrium to become larger and or dilate
3.) a loop in the heart tube occurs and the most caudal portion becomes the most cranial portion and the atrium (A) is rotated about the ventricle (V)
During week 4, the heart tube undergoes looping: the tube _______, walls _______, and sections move towards appropriate locations to continue development
lengthens; thicken
Heart wall
the heart tube pushes out and starts to form walls between the atria and ventricles but the walls do not close all the way due to valve formation
Cushioning formation
4.) cardiac mesoderm in the wall of the atria secretes cardiac jelly (collagen, hyaluronic acid, proteoglycans, and glycosaminoglycans) - the jelly provides an area where mesodermal cardiac cells can migrate and form cushions
Septation
5.) This is a walling off of the ventricles into a L and R division
the walls of the ventricles are thick and septum arises for the floor of the ventricle and extends upwards, becoming more complicated
another septa grows from the top and center
the foramen ovale exists between the atrial septa until later in development to allow blood flow between atria
Septation continued
flaps at the atria are very porous and embryonic circulation bypasses the lungs because the embryo receives O2 from the mother; blood flows from atrium to atrium through the foramen ovale
the foramen _____ is a requirement for blood circulation in the embryo
ovale
At birth, pressure in the L atrium becomes _____ and the flaps at foramen ovale _____ and blood flows on either side of the heart; pressure from both sides _____ ovale
low; close; closes
Congenital heart defects
1.) The foramen ovale is the embryonic passage between the L and R atria
2.) If this hole does NOT close after birth, there is a cardiac septal defect
3.) There are 2 major cardiac septal defects
2 major cardiac septal defects
1.) Atrial septal defect (ASD)
- hole between L and R atria
2.) Ventricular septal defect (VSD)
- hole between L and R ventricles
Embryonic mammal lungs are on hold during gestation
1.) Embryonic lungs are collapsed and resistant to blood flow
2.) Oxygenated blood moves from the placenta -> embryo body -> sinus venosus -> L atria and ventricle -> R atria and ventricle -> embryo body -> placenta
3.) HOLES in the heart allow for this to happen
4.) blood is mixed in the fetal heart and only partially oxygenated
After birth, the lung circulation is activated
1.) The placenta is discarded; the lung circulation begins
2.) Surfactants help expand lung alveoli; blood flow increases
3.) Within days or weeks of birth, the passages between the L and R heart chambers close
4.) Blood now moves from the body -> sinus venosus -> R atrium -> R ventricle -> lungs -> L atrium -> L ventricle -> aorta -> body
2 dorsal aortae fuse into 1 dorsal aorta below arches; 2 ventral aortae fuse into 1 ______ ___
aortic sac
The aortic arch or _________ arch arteries are a series of ___ paired embryological vascular structures which give rise to the great ________ of the _____ and _____
pharyngeal; six; arteries; neck; head
Cells arise and move from aortic sac through the pharyngeal arches (angiogenesis) and those sprout to the _____ aorta to make aortic _____
dorsal; arches
Pharyngeal arch arteries
- they are formed within the arches
- they are ventral to the dorsal aorta
- bilateral symmetry then reorganization
Arch 1 and 2
Arch 1
- Maxillary arteries
Arch 2
- hyoid artery gives rise to stapedial artery
- rare that people keep this artery (only 10% of adult people)
Arch 3
- Common carotid artery
- Internal carotid artery
Arch 4
- also known as the systemic arch
- R -> subclavian artery
- L -> Aortic arch
Arch 5
disappears
Arch 6
- R-> Pulmonary artery (origin disappears)
- L-> Pulmonary artery origin becomes Ductus Arteriosus
Ductus Arteriosus
Connector between aorta and pulmonary trunk
3-____ pairs of pharyngeal arch arteries connect the 2 dorsal aortae with aortic sac
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