Exam 2 - Lecture 28 (Nervous & Cardio Systems) Flashcards
What are the 3 primary vesicles of the brain during development?
- Forebrain
- Midbrain
- Hindbrain
What is another name for the forebrain?
Prosencephalon
What is another name for the midbrain?
Mesencephalon
What is another name for the hindbrain?
Rhombencephalon
What are the 2 layers that make up the wall that surrounds the neural tube?
Mantel layer and marginal layer
What arises from the 3 primary brain vesicles?
5 secondary vesicles
How many vesicles does the forebrain divide into?
2 (1 and 2)
How many vesicles does the midbrain divide into?
1 (3)
How many vesicles does the hindbrain divide into?
2 (4 and 5)
What do the walls of the vesicles eventually give rise to?
Neural structures
What do the 5 secondary vesicles of the brain eventually give rise to?
Cavities/ventricles
What does vesicle #1 give rise to (wall and cavity)?
Wall = cerebral hemispheres Cavity = lateral ventricles
What does vesicle #2 give rise to (wall and cavity)?
Wall = Thalami Cavity = 3rd ventricle
What does vesicle #3 give rise to (wall and cavity)?
Wall = Midbrain Cavity = aqueduct
What does vesicle #4 give rise to (wall and cavity)?
Wall = Pons and cerebellum Cavity = upper part of 4th ventricle
What does vesicle #5 give rise to (wall and cavity)?
Wall = Medulla Cavity = Lower part of 4th ventricle
Which part of the brain gives rise to the only cavity that is not a cavity?
midbrain/3rd vesicle –> aqueduct
What is the definition of a nucleus when we refer to hindbrain development?
Collection of neuronal cell bodies in the CNS
What are the 3 steps to hindbrain/cerebellum formation?
- Rhombic lips form
- Rhombic lips advance toward each other and make contact
- Cells of external germinal layer divide and descend into cerebellum, connecting with Purkinje neurons
What are the 6 steps to forebrain (cerebrum) development?
- Cells/neurons in the mantel layer divide
- Cells pass thru marginal layer
- Cells in mantel layer divide again
- Cells pass thru marginal layer past 1st wave of cells
- Cells in mantel layer divide a 3rd time
- Cells pass thru marginal layer past 2nd wave of cells
Why is gray matter on the outside in the brain?
Successive waves of dividing neurons passing one another after going thru the mantel layer
What 2 things are successive waves of migration important for?
- Formation of sulcus
2. Formation of gyrus
What is a sulcus of the brain?
depression
What is a gyrus of the brain?
elevation
What are the 5 types of brain malformations?
- Cerebellar hypoplasia
- Anencephaly
- Lissencephaly
- Cranium bifidum
- Hydrocephalus
What is cerebellar hypoplasia?
Smaller than normal cerebellum
What is anencephaly?
No brain = lethal
What is lissencephaly?
Smooth cortex (waves of migration arrested)
What is cranium bifidum?
Defect in neural tube formation; skull cannot form normally around the developing brain.
What is hydrocephalus?
Buildup of CSF due to an obstruction that does not allow for its reabsorption –> leads to malformation of the skull
What is another name for cranium bifidum?
encephalocele
What are the two parts of the pituitary gland?
anterior and posterior
What is the relationship between the posterior pituitary and its axon?
Axon projects directly into the posterior pituitary
What is the relationship between the anterior pituitary and its neurons?
Axons terminate on and release its contents onto a portal system which then carries those contents to the anterior pituitary.
From which dermal layer does the entire pituitary gland originate?
ectoderm
Where does the anterior pituitary originate from?
Upgrowth from roof of primitive mouth
Where does the posterior pituitary originate from?
Downgrowth from the floor of the forebrain
What type of return does the right atrium receive and from what vessels?
Systemic return from cranial and caudal vena cava
What is the blood flow FROM the right ventricle?
pulmonary outflow to the lungs
What type of return does the left atrium receive and from what vessels?
Pulmonary return from pulmonary veins
What is the blood flow FROM the left ventricle?
systemic outflow to the aorta
What is the relationship between the pulmonary trunk and the aorta?
The vessels wind around each other
What is the 1st organ to FUNCTIONALLY differentiate?
heart
The heart is the 1st organ to _____ differentiate.
functionally
When do the 1st heart beats occur?
Around the time of neural tube closure (18-19d in dog, 35-38hrs in chick)
The heart moves blood from _____ embryonic vessels thru the embryonic _____.
extra; circulatory system
What are the 4 main stages of heart development?
- Cardiogenic plate
- Single median heart tube
- Cardiac loop
- Partitioning
Where does folding of the cardiogenic plate initiate?
Outside of the embryo
Where does the cardiogenic plate eventually end up?
Inside of the embryo
What are the 3 steps in the folding of the cardiogenic plate?
- 2 endocardial heart tubes form in the cardiogenic plate
- EC heart tubes fuse (1st heartbeat)
- Contractions go caudal –> cranial (simple peristaltic pump)
What is a simple peristaltic pump?
When heartbeats move from caudal –> cranial
What are the 5 primitive heart regions?
- Truncus arteriosus
- Bulbus cordis
- Ventricle
- Atrium
- Sinus venosus
What 2 things do the truncus arteriosus and bulbus cordis become?
- Ascending aorta
2. Pulmonary trunk
What 2 things does the bulbus cordis (only) become?
- Part of right ventricle (conus arteriosus)
2. Small part of left ventricle
What 2 things does the primitive atrium become?
- Right atrium
2. Left atrium
What does the left sinus venosus become?
Coronary sinus
What does the right sinus venosus become?
Part of the wall of the atrium
What two things cause GENERAL formation of the cardiac loop?
- Rotation of heart to the right by differential growth
2. One part grows faster than the other
What are the 4 steps to cardiac loop formation?
- Bulbus cordis and ventricle move caudally
- Atrium and sinus venosus more cranially
- Atrium becomes dorsal to ventricle
- Ventricle lies next to the bulbus cordis
How are the atrium and ventricle connected to each other?
atrioventricular canal
What are the 3 steps to AV canal partitioning?
- Constrictions begin on either side of the AV canal
- Dorsal and ventral endocardial cushions on periphery on AV canal grow towards each other and meet
- Cushions divide AV canal into R and L sides
In what direction must atrial flow be maintained in intrauterine life?
R –> L
How many septa and foramina form during atrial partitioning?
2 septa
3 foramina
