Parturition And Lactation

Question 1

During pregnancy the uterus is

Answer 1

Relaxed and unresponsive to hormones for contractions

Distended

Question 2

2 components of birth (parturition) contractions

Answer 2

1. Mechanical changes

2. Hormones

Question 3

How does Progesterone change in uterus during pregnancy

Answer 3

1. Myometrial relaxation

——I labor contractions

Question 4

Progesterone antagonist is given when

Answer 4

When you want to induce labor and contractions

Question 5

How does Progesterone change in uterus during parturition

Answer 5

Desensitization of Progesterone Receptors (not lower P levels)
= increased Estrogen Receptors

Question 6

How does Estrogen change in uterus during parturition

Answer 6

Estrogen Receptors increase and HIGH response to estrogen
= increase contractions of myometrium + cervical dilation
= increase oxytocin Receptors
= increase GAP junctions
Fetal membrane (placenta) makes more prostaglandins
Increase proteolytic enzymes in cervix - to relax it

Question 7

How does Prostaglandins change in uterus during parturition

Answer 7

Increase Contractions + stretch of cervix
INITIATE LABOR : PGF2a. PGF2 induce contractions at any stage
Potentiates oxytocin made contractions also
REGULATED : uterus stretch, estrogen, oxytocin = release

Question 8

What causes oxytocin to be released

Answer 8

1. ESTROGEN (80x—>200x) higher receptors when 36weeks—>labor

2. stretch in cervix

Question 9

Uterus can only sense oxytocin when

Answer 9

After around week 20

Question 10

Oxytocin does what

Answer 10

SM contraction is uterus

Increase PFG2a in Decidual tissue (part of placenta)

Question 11

Ferguson Reflex

Answer 11

Estrogen (OVARY) stimulates oxytocin receptors (UTERUS)

1. Cervix distention
2. Oxytocin from (fetus and mom PP)
   - Stimulate uterus contractions
   - placenta to make PGF
3. Prostaglandin = more contractions
4. Stimulates PP to release oxytocin

Question 12

Relaxin in parturition

Answer 12

Made by CL, placenta, an decidua (week 38-42)
FUNCTION : uterus relaxed during pregnancy
- softer and help dilate cervix *
- if elevated at week 30 = premature birth

Question 13

Relaxin at week 30

Answer 13

Premature birth

Question 14

Mechanical change of uterus

Answer 14

It stretched to its limit : then causes Ferguson reflex + PGF
Twins have 19 day shorter gestation period

Question 15

INITIATION OF LABOR

Answer 15

1. Placenta makes CRH (late preg and labor)
2. More sensitive uterus to PGF and oxytocin = contractions
3. Increases ACTH in fetus
   - >cortisol = more CRH from placenta
   - > estrogen from placenta = contractions

Question 16

Braxton Hicks contractions

Answer 16

Weak and slow contractions periodically before labor
They become stronger during labor
+ shorten SM + stretch cervix (draw in up)

Question 17

Where is fully dilated cervix

Answer 17

Drawn up just below the pelvic inlet

Question 18

2 stages of labor

Answer 18

1. Shortening cervix : longest time

2. Pushing baby out : less then 1hr

Question 19

How is the placenta removed

Answer 19

Uterus contracts to detach it

Can cause bleeding and clotting

Question 20

What H helps remove placenta

Answer 20

Oxytocin by constricting BVs in uterus

Nipple stimulation + synthetic oxytocin can be given to increase contractions of uterus

Question 21

Breast is superficial to

Answer 21

Pectoralis M

Question 22

Breast has what inside

Answer 22

1. Adipose + CT
2. Lobules inside lobes : glandular units
3. Lactiferous ducts : collect milk from lobules
4. Lactiferous sinus : where most ducts run next to each other before exiting nipple

Question 23

Alveolar epithelium in breasts

Answer 23

Luminal epithelial

Make and secrete milk, lining lumen of duct + alveoli

Question 24

Myoepithelial cells in breast

Answer 24

Around Luminal epithelial cells
REGULATED by Oxytocin ——> Contract
*moves milk from alveoli into the ducts

Question 25

Breast of birth

Answer 25

Almost all lactiferous ducts, not many alveoli | * like this until puberty

Question 26

Breast at puberty on

Answer 26

ESTROGEN ——> lactiferous ducts growth branches and the ends of the branches for alveoli + more fat

Question 27

Breasts during pregnancy

Answer 27

Bolbus terminal endbuds - where milk is made in alveoli

Question 28

Menstrual cycle and breasts

Answer 28

Mammillary glands exposed to estrogen and progesterone = ductal-lobular -alveolar growth = more fat and CT ——> increase breast volume, tenderness, involution *if no pregnancy*

Question 29

Breasts when pregnant

Answer 29

``` Epithelial structures (ducts, lobules, alveoli ) GROW CT + Adipose DECREASE ```

Question 30

3rd trimester and breasts

Answer 30

Parenchymal cell growth slows | Aveoli get distended + has early colostrum (due to prolactin)

Question 31

Lactating breasts

Answer 31

MANY alveoli Not a lot of CT or fat PROLACTIN + OXYTOCIN + DOPAMINE *Low E and P, pulsatile prolactin made

Question 32

Prolactin and breasts

Answer 32

Milk production

Question 33

Dopamine and breasts

Answer 33

Inhibit production of milk

Question 34

Oxytocin and breasts

Answer 34

Ejection of milk

Question 35

Making milk : SECRETORY PATHWAY

Answer 35

Epithelial cells in aveoli make proteins in the Golgi——> secreted into lumen (milk proteins like acidic proteins, caysine)

Question 36

Making milk : Transcellular endocytosis and exocytosis PATHWAY

Answer 36

Endothelial cells take up other proteins made elsewhere like Ig bodies and endocytose and then exocytosis into lumen

Question 37

Making milk : Lipid PATHWAY

Answer 37

Milk fats moving into cell to lumen , diffusion

Question 38

Making milk : transcellular salt and water PATHWAY

Answer 38

Membrane transporters are on both sides on the epithelial cells

Question 39

Making milk : Paracellular PATHWAY

Answer 39

Movement of substances between cells | Immune cells, and other things

Question 40

Colostrum

Answer 40

First milk that is made in the milk (Will change in composition over time) HIGH in fats, Ig, sugar

Question 41

How is prolactin stimulated

Answer 41

Nipple stimulation

Question 42

When does prolactin increase

Answer 42

At the end of pregnancy

Question 43

Milk made in the cells are released due to what

Answer 43

Prolactin | And this is inhibited if no milk is being released or ejected, lower milk will be made

Question 44

Oxytocin stimulated

Answer 44

``` Myoepithelial cells Nipple suck (sight, sound, smell of infant)——> CNS + PP ———> OXYTOCIN—> Myoepithelial cells ```

Question 45

Early lactation has what impact on the hypothalamus

Answer 45

——I GnRH to lower LH and FSH | = inhibit ovarian cycle , comes back after some weeks of nursing

Question 46

Prolactin pathway

Answer 46

Nipple suck—> hypothalamus release Dopamine inhibiting factor = no Dopamine = Lactotrophs are active + Prolactin activated milk production

Question 47

When is sucking nipple signal milk stopped

Answer 47

1. Epithelial cells distended and atrophy *apoptosis* = rupture wall of alveoli = capillaries compress —> alveolar hypoxia (they die) 2. Debris phagocyted 3. Lobules decrease in size 4. Involution (takes up to 3mos)

Question 48

What H. Plays biggest role to makes breast grow

Answer 48

Estrogen