Chapter 17 Flashcards
what is a zygote
Single cell that results from the fertilisation of an egg by a sperm
what is a blastocyst
A hollow ball of cells that surround a fluid filled cavity
what is the inner cell mass
Group of cells in the blastocyst that develop into the embryo
What are stem cells
cells that have the ability to produce different types of body cells. Found in the inner cell mass
what is IVF
fertilisation outside of the mothers body
what is proliferation
the process where cells replicate themselves
what is differentiation
the process by which unspecialised cells develop special characteristics to suit particular functions
how does differentiation occur
When stem cells proliferate different genes become activated. Results in differentiation into specialised cells that are able to perform particular functions
what are the internal signals that trigger differentiation
The cells genes turned ‘on’ or ‘off’
what are the external signals that trigger differentiation
secretions by other cells, contact with other cells and molecules in its surroundings
what are the three types of stem cells
Totipotent, Pluripotent, Multipotent
what are totipotent stem cells
a stem cell able to create any of the types of cell necessary for embryonic development. (eg. a zygote). After 5 days, specialise into a blastocyst
what are pluripotent stem cells
stem cells that are able to give rise to many but not all cell types. (eg. Inner cell mass - give rise to foetal tissues but not placental tissue).
what are multipotent stem cells
stem cells that are able to give rise to a limited number of other cell types. (eg. blood stem cells will give rise to RBC’s, WBC’s and platelets)
what is the embryonic period
the first two months of pregnancy
when is a developing individual called a foetus
after the second month
what maintains the endometrium
First through corpus luteum (progesterone + oestrogen) then via placenta. Development of blastocyst depends on endometrium being maintained
what are primary germ layers
the embryonic tissues from which all tissues and organs will develop. The ectoderm, Mesoderm and endoderm
what is the ectoderm
Outer tissue layer of embryo. Gives rise to the entire nervous system, Epidermis of skin, and the lens, cornea and muscles of the eye
what is the Mesoderm
Middle tissue layer of the embryo. Gives rise to skeletal smooth and cardiac muscles, Lymphoid tissue and the dermis of skin
what is the endoderm
Inner tissue layer of the embryo. Gives rise to epithelium of alimentary canal and its glands (liver, pancreas), Epithelium of bladder, urethra and call bladder and epithelium of vagina and associated glands
what are the two embryonic membranes
Amnion and Chorion
what is the amnion
the membrane that forms a cavity around the embryo. Secretes amniotic fluid into the cavity to protect the embryo
what is the chorion
Outermost embryonic membrane that eventually fuses with the amnion to form the a part of the foetal part of the placenta
