Vertebrate Body Plan Week 3 Flashcards
The __________ mesoderm forms the urogenital system.
Intermediate mesoderm
The _________mesoderm forms the future body wall.
Lateral plate mesoderm
Where does the notochord derive from?
Mesoderm
What does the notochord form into?
It is the precursor to the axial skeleton by forming nucleus pulposus
What else forms around the notochord? (2 names)
Vertebral bodies also called the primitive chordata
What are somites? What are they made of?
Somites are epithelial balls of cells formed in segmental pairs along the neural tubes from the paraxial mesoderm.
What is neurulation?
Neurulation is the formation of the neural tube that eventually becomes the CNS.
Describe the three steps of neurulation
- The notochord forms from mesoderm cells after gastrulation is complete.
- Signals from notochord cause inward folding of the ECTODERM at the neural plate.
- Ends of the neural plate disconnect to form the autonomous neural tube.
During neurulation, what germ layer folds inwards?
Ectoderm
What is the fetal period?
Weeks 9-38; all organs are developed, size enlargement is occuring.
Clinicians use ________ age to determine due date.
Gestational age
Describe the difference between fertilization and gestation.
Fertilization begins at conception.
How long is the birth period “gestationally” vs based on the fetal age.
40 weeks and 38 weeks respectively
During which time period will death of the embryo occur due to congenital anomalies?
0-3 weeks
During which time period will malformation of the embryo occur? What is an example?
3-8 weeks (heart defect)
During which time period will their be functional disturbance of a fetus?
8-38 weeks (mental deficiency)
What is a birth defect?
Term for congenital malformation such as a physical anomaly.
What is a congenital disorder?
A condition existing at birth and often before birth that develops during the first month of life regardless of causation
Teratology
Study of causes and biological processes leading to abnormal development
Teratogen
Any agent that causes a birth defect
What are the 3 key characteristics of vertebrate body plan?
Bilateral, Body Cavity (tube within tube) and Vertebrate
What is organeogensis?
The development of organs from Weeks 3-8
Describe the teratology of thalidomide
Thalidomide was used as medication to reduce morning sickness among pregnant woman but it also ended up causing birth defects. Scientists did not know drugs could cross the placental barrier.
When is limb development at a critical period ?
Weeks 4 and 5
When is heart development at a critical period?
Weeks 3-6
Describe the birth defect thalidomide caused.
Phocomelia; blood supply to formation of long bones is inhibited by thalidomide causing limb development to results in majority shoulders.
Who is susceptible to congenital anomalies?
Higher maternal age, genetic predispositions, environmental factors
What is the migration pattern of epiblasts?
Caudal to Cranial , Mesial and Lateral
What do somites differentiate into?
Vertebrae, muscles of the back and body, dermis of the skin
