Group 3- set 2/3- Placental Function - revision period - COMPLETE ****

Question 1

State 6 functions of the placenta

Answer 1

delivery of gases
delivery of nutrients
energy storage
excretion of waste products
placental derived hormones
barrier to toxic substances

Question 2

State the overall pattern of growth of the placenta and foetus during pregnancy
- What does this indicate about the placenta?
- How is this enabled?

Answer 2

most placental growth occurs in the first half of pregnancy
most foetal growth occurs in the last trimester of pregnancy

that placental efficiency must increase with gestation in order to support the foetus

increased uterine and umbilical blood flow

Question 3

Nutrient and Gaseous Exchange: How so many substances transfer from maternal to foetal blood?
- State 5 factors which influence this process and explain why

Answer 3

by passive diffusion

blood flow

structure influences the area for exchange

morphology influences the number of tissue barriers against the exchange

electrical gradient - a slight negative charge encourages positive charged ions to diffuse across

concentration gradient for exchange between maternal and foetal blood

Question 4

Which types of placenta, in terms of morphology (layers of tissue) are most efficient for exchange of substances? - state them in order of most efficient to least efficient

Answer 4

haemochorial
endotheliochorial
epitheliochorial

Question 5

How are amino acids and glucose transferred to foetal blood?
- if done by active transport, how does this work?

Answer 5

passively and by active transport

specific carrier molecules for amino acids and glucose work to move these molecules against the concentration gradient from maternal to foetal blood

Question 6

Endocrine Placenta: Give the hormones produced by the placenta

Answer 6

progesterone
oestradiol
prolactin
relaxin
placental lactogen

Question 7

Endocrine Placenta - Progesterone: What other structure produces progesterone for a portion of pregnancy?
- What stimulates the placenta to start secreting progesterone?

Answer 7

the corpus luteum

the production of LH, prolactin and oestrogens

Question 8

Endocrine Placenta - Progesterone: What is the function of Progesterone during pregnancy? 3
- What would a progesterone antagonist do?

Answer 8

suppress myocetrial contractility
stimulate production of histotroph
stimulate mammary gland development

induce abortion

Question 9

Progesterone Profiles: Explain why progesterone secretion is not simple during pregnancy 2

Answer 9

the corpus luteum is the source of progesterone for the first part of pregnancy
but in some species the placenta will take over progesterone production

Question 10

State the gestation length and time for placental progesterone ‘take over”:

• Bitch
• Queen
• Rabbit
• Goat

Answer 10

65 days and no placental takeover
65 days and no placental takeover
30 days and no placental takeover
150 days and no placental takeover

Question 11

State the gestation length and time for placental progesterone ‘take over”:

• Sow
• Cow
• Ewe
• Mare

Answer 11

114 days and no placental takeover
283 days and between days 150-240
145 days and on day 50
330 days and between days 140-210

Question 12

For species with no placental takeover, what is the significance of this? 2

Answer 12

it means that the corpus luteum is the only source of progesterone
so if the corpus luteum is removed at any time during pregnancy the pregnancy will be terminated

Question 13

Endocrine Placenta: Oestrogens
- Is Oestradiol the only type of oestrogen produced during pregnancy? 3

Answer 13

no, humans produce oestriol
ruminants produce oestrogen
horses produce equine specific oestrogens

Question 14

Endocrine Placenta: Oestrogens
- What is their function? 5

Answer 14

stimulate placental growth
stimulate myocetrial growth
stimulate mammary development
increase uterine blood flow
preparation for parturition

Question 15

Endocrine Placenta: Prolactin
- Other than the placenta, where else is prolactin produced?
- What can prolactin secretion be stimulated by?
- What can prolactin secretion be inhibited by?

Answer 15

the anterior pituitary gland

oestradiol
dopamine

Question 16

Endocrine Placenta: Prolactin
- What are the functions of Prolactin? 3

Answer 16

stimulates lobuloalveolar growth and locatogenesis in the mammary gland
stimulates maternal behaviour
stimulates progesterone production from the corpus luteum of dogs and rodents

Question 17

Endocrine Placenta: Relaxin
- Where is relaxin produced?
- Do cattle secrete relaxin?

Answer 17

by the corpus luteum in sow
by placenta in bitch queen mare rabbit

no but relaxin-like factor is produced which is an equivalent hormone

Question 18

Endocrine Placenta: Relaxin
- What are the functions of Relaxin? 3

Answer 18

softening of connective tissue enabling growth of foetus
relaxation of pelvic ligaments
role in parturition

Question 19

Endocrine Placenta: Relaxin
- What is the significance of relaxin in dogs and cats?

Answer 19

it can be used to diagnose pregnancy

Question 20

Endocrine Placenta: Placental Lactogen
- Which hormone is placental lactogen similar to and in what way?
- Where is it produced?
- Where is it released into?

Answer 20

prolactin
placental lactogen binds to prolactin receptors

binucleate cells of the placenta in ruminants

maternal and foetal circulation

Question 21

Endocrine Placenta: Placental Lactogen
- What is its function? 2

Answer 21

modulates foetal metabolism
stimulates mammary gland development

Question 22

Endocrine Placenta: State other specific placental hormones in Ruminants that could be sued for pregnancy diagnosis in cattle
- Why are these specific to ruminants?

Answer 22

pregnancy specific protein B PSPB
pregnancy associated glycoprotein PAG

because they are produced by binucleate cells

Question 23

Endometrial Cups: When do the equine endometrial cups start appearing?
- What do they do?

Answer 23

about day 40

produce equine chorionic gonadotrophin

Question 24

Endometrial Cups: These cups produce ECG
- How does ECG behave?
- What is its function? 2
- What happens eventually to the accessory corpus luteums?

Answer 24

like FSH and LH

it increases progesterone secretion form the primary corpus luteum for a short period of time
it then induces the formation of an accessory corpus luteums

their activity will decrease and plasma progesterone levels will decrease

Question 25

Endometrial Cups: After the accessory corpus luteums activity ceases, how is progesterone maintained for the remainder of pregnancy?
- but how is this possible if there is such a drop in progesterone concentration of the progesterone profile?

Answer 25

by placental progestogens

unique progestogens are made which act locally

Question 26

Unique Progestogens in the mare: State the main Progestogen

Answer 26

5-alpha-pregnane

Question 27

Pregnant Bitch: Compare the luteal phase between pregnant and non-pregnant bitch
- What main hormones does the placenta produce in low levels?
- What is the corpus luteal progesterone secretion dependent on?

Answer 27

there is a prolonged luteal phase in both

oestrogens and progestogens

LH and prolactin

Question 28

Pregnant Bitch: When can you separate progesterone profile from non-pre and pregnant bitch and how?

Answer 28

at day 21 there will be a rapid rise in progesterone in the pregnant bitch divergent from the non-pregnant profile

Question 29

Effects of Prostaglandin: When would the administration of Prostaglandin F2 alpha be effective in terminating a pregnancy of the following species:

• Cow
• Ewe
• Sow
• Mare
• Goat
• Bitch
• Queen

Answer 29

up to day 150
up to day 45
throughout pregnancy
up to day 35
throughout pregnancy
throughout pregnancy
throughout pregnancy