Development Of A Human Embryo

Question 1

What are sperm and egg brought together by?

Answer 1

Fertilisation

Question 2

What is a zygote?

Answer 2

A single cell that results from the fertilisation of an egg by a sperm.

Question 3

After fertilisation, where does the zygote travel to and what happens?

Answer 3

The uterine tubes and begins to divide by mitosis.

Question 4

After about 6 days of fertilisation, the original zygote has reached the uterus and has developed into what?

Answer 4

A blastocyst - a hollow ball of about 30 cells called the inner cell mass (sometimes known as the embryoblasts)

Question 5

The ICM will developed into the ________, and the cells that compose it are termed _____ ______, which are able to produce different types of body cells.

Answer 5

The ICM will developed into the embryo, and the cells that compose it are termed stem cells, which are able to produce different types of body cells.

Question 6

What does implantation provide for the blastocyst? Where does it comes from?

Answer 6

It provides nourishment for growth and development by absorbing nutrients from the glands and blood vessels of the endometrium.

Question 7

The amnion sac is enclosed with what? What does the substance provide the embryo with?

Answer 7

The amnion sac is filled with amniotic fluid which serves to protect the embryo against physical injury by acting as a shock absorber. It also helps maintain a constant temperature and allows the foetus to move freely.

Question 8

What’s another embryonic membrane besides the amnion?

Answer 8

The chorion, which is formed from the outer cells of the blastocyst together with a layer of mesodermal cells. (Page 226)

Question 9

What is the placenta?

Answer 9

An organ that supplies nutrients tom and removes wastes from, the foetus. It is a combination of foetal and maternal tissues.

Question 10

How long does it take for the placenta to completely form?

Answer 10

It’s fully formed by the end of the third month.

Question 11

List the functions of the placenta.

Answer 11

Endocrine - secrete hormones necessary for maintaining pregnancy
Excretory - trans of nitrogenous wastes
Immune - trans of antibodies
Nutritional - trans of nutrients
Respiratory - trans of oxygen and CO away

Question 12

What are chronic villi?

Answer 12

Finger-like projections that develop from the outer layer of cells.

Question 13

How does the exchange of materials take place from the mother of the foetus?

Answer 13

Diffusion and active trans.

Question 14

The placenta is attached to the foetus by the?

Answer 14

Umbilical cord

Question 15

Why are stem cells different from other cells? (3)

Answer 15

1) they are not specialised for any particular role
2) they are capable of repeated division by mitosis
3) they can differentiate into specialised cells.

Question 16

What is the term used when cells rto placate themselves many times over?

Answer 16

Proliferation.

Question 17

What is differentiation?

Answer 17

The process by which unspecialised cells develop characteristics and the function of particular types of cells such as blood, muscle, nerve and bone cells.

Question 18

What are genes?

Answer 18

Genes are interspersed across long stands of DNA and carry coded instructions for all the structures and functions of a cell.

Question 19

Why could stem cells potentially provide an unlimited source of adult cells?

Answer 19

Because they have the ability too develop into any cell type.

Question 20

What is a totipotent stem cells?

Answer 20

The fertilised egg has the potential to create any type of cell necessary for embryonic development, the embryo itself, and the membranes associated with embryonic development.

Question 21

What type of stem cells are the ICM called?

Answer 21

Pluripotent stem ✂️📗📗📌📗📂📌📗📔📌📗📔🔗

Question 22

What do totipotent stem cells do?

Answer 22

Give rise to all the cell types that make up the human body and all the cell types that make up the membranes that surround the developing embryo (including the placenta).

Question 23

What does the pluripotent stem cells do?

Answer 23

Give a rise to all the cell types that make up the body but not the cell types that make up the embryonic membranes

Question 24

What does the multi potent stem cells do

Answer 24

Can develop into mor than one of the cell types that make up the body but not all cell types

Question 25

What hormone does the corpus luteum produce and what does it do?

Answer 25

CL produces the hormones:

Maintains the endometrium lining from breaking down.

Question 26

While the blastocyst is implanting, the ICM undergoes changes resulting in primary germ layers. Name these 3 layers and what they develop into.

Answer 26

Ectoderm, mesoderm and endoderm

- they are the embryonic tissues that will differentiate into all the tissues and organs of the body.

Question 27

What does the endoderm form?

Answer 27

Epithelium of the alimentary canal and its glands, epithelium of the urinary bladder, urethra and gallbladder. Epithelium of pharyn, auditory canal, etc, epithelium of tonsils p, thyroid, parathyroid and thymus glands, epithelium of vagina and associated glands.

Question 28

What structues does the medoderm produce in the body?

Answer 28

4 types of tissues, lymphoid tissue, endothelium of blood vessels and lymphatic, epithelium of body cavity, joint cavities, kidney, ureters, ovaries, testes, reproductive tract and adrenal cortex.

Question 29

What structures does the ectoderm produce in the body?

Answer 29

Epidermis of skin

Hair, nails, glands of skin, etc

Question 30

Name the four embryonic membranes.

Answer 30

Amnion, amniotic fluid and chorion.

Question 31

By the end of the first two months of embryonic life, what has formed

Answer 31

The general body form of the infant has developed and the basic plan of the organ systems is in place,