2.2 physiology and health (2)

Question 1

State the location of the endometrium

Answer 1

The endometrium is the lining of the uterus

Question 2

What happens to the endometrium during the menstrual cycle

Answer 2

During the course of a menstrual cycle the endometrium changes as a result of hormonal signals from the ovary

Question 3

How many days does it take the endometrium to shed (menstrual cycle 1)

Answer 3

During days 1 to 5 the endometrium is shed – this is the menstrual bleed

Question 4

How does the endometrium get repaired after its shed (menstrual cycle 2)

Answer 4

Then the endometrium repairs as oestrogen stimulates proliferation from days 5 to 14 preparing it for a possible implantation event

Question 5

What happens days 14-22 (menstrual cycle 3)

Answer 5

From days 14 to 22, further development and vascularisation of the endometrium is stimulated by progesterone to ensure that it is a thick blood rich layer ready to sustain an implanted embryo

Question 6

What happens if theyre is no fertilisation (menstrual cycle)

Answer 6

If there is no fertilisation, then from days 22 to 28 the progesterone levels fall and the endometrium starts to break down in preparation for menstruation from days 1 to 5 as the cycle continues.

Question 7

Identify the two phases of a menstrual cycle

Answer 7

Follicular phase – Days 1 to 14
Luteal phase – Days 15 to 28

Question 8

Outline the events that occur in the ovaries and endometrium during the follicular phase of the menstrual cycle.

Answer 8

During the follicular phase, a follicle develops in the ovary and oestrogen is secreted. At the start of the follicular phase, the endometrium is being shed (menstruation) and then during the rest of the follicular phase, the endometrium is being repaired (proliferation).

Question 9

Identify the event that signals the end of the follicular phase and the start of the luteal phase.

Answer 9

The end of the follicular phase is signalled by the process of ovulation when a mature follicle ruptures to release an egg and luteal phase begins.

Question 10

Outline the events that occur in the ovaries and endometrium during the luteal phase of the menstrual cycle.
(Luteal phase 1)

Answer 10

During the luteal phase, the remains of the Graafian follicle develops into corpus luteum which then starts to secrete progesterone

Question 11

What happens at the start of the luteal phase of the menstrual cycle
(Luteal phase 2)

Answer 11

At the start of the luteal phase, the endometrium is becoming vascularised to form a thick blood rich layer ready for implantation of an embryo

Question 12

What happens if there is no pregnancy (Luteal phase 3)

Answer 12

If there is no pregnancy, then in the second half of the luteal phase the corpus luteum starts to degenerate and as the progesterone levels start to fall, the endometrium starts to break down in preparation for the next menstrual bleed at the start of the next follicular phase.

Question 13

Describe the events involved in the formation of a blastocyst.

Answer 13

If an egg (ova) is successfully fertilised by a sperm, this forms a zygote. The zygote then starts to divide by mitosis creating a ball of cells called a blastocyst.

Question 14

Describe the process of blastocyst implantation.

Answer 14

As the fertilised egg is undergoing cell division, it continues to travel though the oviduct towards the uterus. By the time the zygote gets to the uterus it has become a blastocyst (ball of cells).

Question 15

What happens after the uterus becomes a blastocyst (Blasctocyst implantation 2)

Answer 15

The blastocyst will then implant into the blood rich endometrium lining the uterus

Question 16

What happens during this process (blastocyst implantation 3)

Answer 16

During this process of implantation, the blastocyst grows blood vessels into the endometrium forming chorionic villi. These structures are the initial
stages in the formation of a placenta to allow exchange of materials between the maternal blood supply and the foetal blood supply.

Question 17

What causes negative feedback effect on ovarian hormones

Answer 17

High levels of progesterone (ovarian hormone) act on the pituitary gland inhibiting the secretions of FSH and LH (the pituitary hormones).

Question 18

Whats the purpose of negative feedback control (nfc in ovarian hormones)

Answer 18

The purpose of this negative feedback effect is to prevent the development of further follicles while there is the possibility of a successful fertilisation and implantation.

Question 19

What happens when a pregnancy occurs (nfc on ovarian hormones)

Answer 19

If a pregnancy occurs, then this inhibition of FSH and LH continues as the corpus luteum does not degenerate and then the developing placenta takes over the secretion of progesterone.

Question 20

What happens if there is no fertilisation (nfc ovarian hormones)

Answer 20

If there is no fertilisation, then the corpus luteum will start to degenerate and progesterone levels will fall. This removes the inhibition of the pituitary gland and so secretions of FSH and LH trigger the development of a new follicle in the ovaries starting a new menstrual cycle.

Question 21

How long does a typical menstrual cycle take

Answer 21

approximately 28 days

Question 22

What days does menstruation take

Answer 22

typically day 1 to 5

Question 23

what days does the follicular phase take

Answer 23

typically occurs from day 1 to day 14 where levels of oestrogen are increasing.

Question 24

What days does the menstrual cycle take place

Answer 24

around the mid-point, day 14, of the menstrual cycle where LH is at its peak levels

Question 25

What days does the Luteal phase typically occur

Answer 25

day 14 to day 28.

Question 26

When does the develpoment of the corpus luteum occur

Answer 26

Development of the corpus luteum occurs after ovulation, typically from days 14 to 22 accompanied by an increase in progesterone levels.

Question 27

What days does the corpus luteum start to degenerate

Answer 27

The corpus luteum starts to degenerate at around day 22 in a typical cycle leading to a decline in progesterone levels.