DEVELOPMENTAL BIOLOGY Flashcards
What are the cyclical phases of human development
Reproduction Fertilisation Cleavage Gastrulation Neurulation Organogenesis Growth and maturation Puberty Reproduction
What can the first trimester be called
the embryonic period
after this it becomes the foetal period
How does a pregnancy test work
Human chorionic gonadotrophin (hCG) hormone is secreted by the placenta after embryo implantation (day 7-8)
Detected in blood and urine
What is an ectopic pregnancy
Where implantation does not occur in the uterus, but outside of the uterus.
90% are tubal causing bleeding and tubal miscarriage
What is hydatidiform mole
only the trophoblast proliferates and not the ICM. No embryo develops
hCG still secreted giving +ve on test, needs ultrasound to confirm
Symptoms: abnormal growth and vaginal bleeding
Outline neural crest cells
Cells derived from junction of neural plate and epidermis. Undergo EMT and migrate down tracks due to growth factors.
Gives rise to:
- craniofacial region (cartilage and bone)
- odontoblasts (dentine of teeth)
- melanocytes
- heart
- brachial arch derivatives (throat)
- PNS
What specific structures do neural crest cells give rise to
Cranial: bone and cartilage of face/neck, cranial nerves, bones of ear and jaw
Cardiac: outflow tract of heart, neurons
Trunk: sympathetic neutrons of dorsal root ganglia (sensory), melanocytes of dermis
Sacral: parasympathetic nerves (enteric ganglia) of gut
What is a neural tube defect and what are 2 forms
Failure of neural tube closure in first trimester
Anencephaly: cephalic part of neural tube fails to close, absence of major portion of brain (deaf, blind, unconscious)
Spina bifida: posterior neural tube fails to close, vertebrae remain open, spinal cord exposed, neural disability (risk reduced by folic acid)
Outline cardiogenesis
Development of the heart.
Two tubes fuse at the midline and fold to form the heart. Tubes also contribute to blood vessel formation
What is a congenital birth defect
Abnormalities of development present at or before birth.
first trimester is most sensitive
nervous system is most sensitive to issues over whole process of development
2 types: genetic or environmental (from teratogens)
Example of a single gene defect
Duchenne muscular dystrophy: muscle degradation
x linked recessive disorder
Mutation of dystrophin gene which encodes for dystrophin
Dystrophin connects cytoskeleton of muscle fibre cells to the surrounding ECM
What is a syndrome
A variety of different effects due to several genes being affected.
What are imprinting genes
Differences in activation of genes depending on the parental origin of the chromosome
e.g. one gene may be off in father and on in mother. If mothers then is mutated then both genes will be off and there will be no gene working
What is a chromosomal defect
Larger scale and cause a loss or gain of DNA. Genes are unaltered but a chromosome is duplicated or deleted
e.g. trisomy 21 = down syndrome
Outline the human cerebral cortex
much more folded so more neurons and connections between regions
high development in parts for sensory perception, conscious thought, language, abstraction and problem solving
