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A2 Chapter 1 > 1.5 > Flashcards

1.5 Flashcards

0
Q

As the chorionic villi develop, they become surrounded by maternal blood spaces. This provides a

A

Large surface are over which the foetus can obtain nutrients and exchange gases with the mother’s blood

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1
Q

Some of the cells in the blastocyst form

A

Chorionic villi that secrete enzymes to digest the outer layer of the endometrium

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2
Q

Chorionic villi =

A

Beginning of the placenta

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3
Q

the cells in the inner mass of the blastocyst differentiate into the

A

Many different kinds of cell that makes up tissues and organs

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4
Q

25 days after ovulation the embryo has a

A

Primitive bating heart

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5
Q

4 weeks after ovulation the

A

Brain is growing rapidly
The eyes and ears have started to form
Gut is beginning to develop

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6
Q

10 weeks after fertilisation the

A

Main body organs have formed and the embryo becomes a foetus
Main body organs have now formed
Foetus only about 35mm long from rump to head

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7
Q

The foetus is protected inside a sac called the

A

Amnion

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8
Q

Amnion secretes

A

Amniotic fluid

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9
Q

The umbilical cord connects the foetus to the placenta and carries

A

Blood between the two

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10
Q

Umbilical cord contains 2 umbilical arteries, carrying blood from the foetus to the placenta and an umbilical vein carrying blood

A

From the placenta to the vein

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11
Q

The foetus depends on the placenta for its development. Nutrients pass from the mother’s blood into the foetus’ blood in the placenta such as:

A 
Glucose
Amino acids
Mineral ions
Water
Oxygen
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12
Q

Antibodies also pass from the mother to the foetus so that the foetus is protected from the same diseases as the

A

Mother

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13
Q

Immunity from these antibodies lasts for a short time after birth as the foetus does not

A

Produce it’s own memory cells

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14
Q

The placenta contains a large number of chorionic villi and the capillaries are separate from the maternal blood by a thin membrane that has

A

3 layers

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15
Q

3 layers of the membrane are:

A
  • wall of the villus, consists of a thin layer of fused cells (micro villi which considerably increase surface area)
  • a thin layer of connective tissue
  • endothelium cells making up the capillary wall
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16
Q

The mothers blood and the foetal blood flow in opposite directions know as

A

Countercurrent flow

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17
Q

Countercurrent flow ensures that there is a

A

Concentration gradient all the way along the capillary

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18
Q

CCF - blood from the foetus arriving in the placenta has a very low oxygen concentration (0) but it receives oxygen by diffusion from the mothers blood which has a higher oxygen concentration:

A

(2)

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19
Q

the blastocyst and the developing placenta produce the hormone

A

Human chorionic gonadotrophin (hCG)

20
Q

hCG is secreted in large amounts in the first 2 months of pregnancy and is

A

Present in the urine of pregnant women

21
Q

Presence of hCG forms the

A

Basis of pregnancy tests

22
Q

In the first 3 months of pregnancy, the corpus luteum continues to Secrete progesterone and a small amount of oestrogen. This inhibits

A

Contraction of the myometrium

Maintains the endometrium

23
Q

After the first 3 months of pregnancy, the corpus luteum begins to

A

degenerate and the placenta secretes increasing amounts of progesterone together with some oestrogen

24
Q

Progesterone also inhibits the production of FSH

A

from the pituitary gland

25
Q

Screening in pregnancy :

A

Amniocentesis

Samples of chorionic villi

26
Q

Amniocentesis a hypodermic needle is inserted through the mother’s abdomen and a small sample of amniotic fluid is extracted. This will

A

Contain some foetal cells

27
Q

Amniocentesis the needle is guided into a suitable position by using an

A

Ultrasound scan

28
Q

Amniocentesis the cells are extracted and stimulated so that they

A

Divide by mitosis

29
Q

A spindle inhibitor is then added so that the cells do not complete

A

Mitosis

30
Q

The cells are placed in a dilute salt solution so that they swell cupcake then chromosomes are photographed. The images of the chromosomes are then manipulated on a computer screen and

A

Arranged in homologous pairs - enables chromosome defects to be detected

31
Q

Sample of chorionic villi involves using a plastic catheter inserted through the

A

Vagina

32
Q

After 3-4 days zygote has formed a ball of cells called a

A

Morula

33
Q

By about 5-6 days it has formed a

A

Blastocyst

34
Q

The outer layer of cells on a blastocyst (trophoblast) will develop into the

A

Membranes around the embryo and the beginnings of the placenta

35
Q

The inner cell mass of the blastocyst is the part from which the

A

Embryo will develop

36
Q

The blastocyst reaches the uterus about a week after fertilisation takes a few days for

A

Implantation to occur

37
Q

zona pellucida surrounding blastocyst breaks open and the trophoblast cells at one end of the embryo form villi that secrete enzymes-

A

Digest the outer layer of the endometrium releasing nutrients for the developing embryo

38
Q

4 functions of the placenta:

A
  • allows female mammals to carry young inside during early development
  • during pregnancy, foetus receives all it’s nutrients via the placenta
  • all the waste products in the foetus’ blood are removed via the placenta
  • the placenta also produces hormones
39
Q

Placenta consists of thousands of chorionic villi that project into the endometrium. The maternal blood vessels surrounding the chorionic villi break down forming

A

Maternal blood sinuses

40
Q

Placenta is surrounded by capillaries which cause a larger surface area

CO2 from
O2 from

A

Chorionic villi to placenta

Placenta to chorionic villi

41
Q

Placenta hormones

A

Human chorionic gonadotrophin

Progesterone

Oestrogen

Follicle stimulating hormone

42
Q

Functions of placenta:

A

Barrier
Immune protection
Site of exchange

43
Q

Placenta acts as a barrier

A

Limits the transfer of blood components from maternal blood to foetal system

Cells of the maternal immune system do not cross so reducing risk of immune rejection

44
Q

Placenta act as a immune protection

A

Protective molecules cover the surface of the early placenta, ‘hiding’ it from the maternal immune system

45
Q

Placenta acts as a site of exchange as

A

Of many dilutes between maternal and foetal systems

46
Q

Foetus haemoglobin has a higher

A

Affinity for oxygen then maternal haemoglobin

47
Q

Endocrine function

A

The placenta takes over the production of oestrogen and progesterone as the corpus luteum degenerates ensuring the endometrium is maintained

A2 Chapter 1 (10 decks)

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