201 L12 Flashcards
Reproduction
What are the purpose of breasts?
Nutrition of young
Spacing of pregnancies
What are mammary glands?
Modified sweat glands
What tissue are mammary glands derived from?
From tissue that is first identified in the mammary/milk crests and develop between the armpits and the groin.
Where is abnormal breast development likely to occur?
Along the lines of the mammary crests.
Derivation of the breast;
Breast development begins with the formation of ——— —– at about — weeks
The first development takes place as a ——– growth of the ———- to form the ——— breast bud
Secondary buds develop from the ——— bud.
These secondary buds will become the ———- —–, which convey the —— from the —— producing tissue inside the breast to the ——)
As ———– progresses the buds develop ——— (become canalised)
Canalisation is induced by the ——— steroids ——— and ————-.
Breast development begins with the formation of mammary buds at about 6 weeks
The first development takes place as a downward growth of the epidermis to form the primary breast bud
Secondary buds develop from the primary bud.
These secondary buds will become the lactiferous ducts, which convey the milk from the milk producing tissue inside the breast to the nipple
As gestation progresses the buds develop lumens (become canalised)
Canalisation is induced by the placental steroids estrogen and progesterone.
By birth can the breasts potentially make milk?
Yes
When are the breast fully developed?
By birth
What is required for milk production?
Hormonal stimulus
At birth some babies make a colostrum-like secretion called witch’s milk. what causes this?
Because the fetus has been exposed to the placental steroids and maternal hormones they are able to form this secretion.
Name the external structure of the breast described below;
Has many different shapes
Body of the breast
Name the external structure of the breast described below;
Is usually raised, cylindrical and pigmented
Nipple
Name the external structure of the breast described below;
Pigmented circle of tissue that surrounds the nipple.
Areola
What internal structure joins the skin at the nipple?
lactiferous ducts
What external structure contains sebaceous glands which give a granular texture to the surface?
Areola
What is the major component of the breast?
Adipose tissue of the pectoral fat pad.
What is the function of the pectoral fat pad?
Give the breast its texture and shape
What ligaments are the breasts supported by?
Cooper’s ligaments
What factors effect the function of the cooper’s ligaments?
What does this result in?
Age
Hormones
Less support
What do the cooper’s ligaments do?
Hold up the breast
How many lobes are there in the breast and what are they made up of?
15-20 lobes made up of milk secreting lobules
Each of the lobules connects to a single ——— —–.
Lactiferous duct
Each of the lobules in the breast connects to a single ——— —–.
Lactiferous duct
The ———– ——– runs towards the nipple and expands into a —– ——–.
The ——- —– open onto the nipple to allow ——– of the ——.
The lactiferous duct runs towards the nipple and expands into a lactiferous sinus (the broadening of the lactiferous duct).
What is the function of the lactiferous sinus?
Additional storage of milk
When do the breast ducts have active alveoli?
What triggers their growth?
At puberty
Estrogen and progesterone
What is the resting, non-pregnant, non-lactating breast tissue dominated by?
The duct system and fat
NOT THE MILK PRODUCING ALVEOLI
What promotes the growth of alveolar buds during menstruation?
Estrogen and progesterone
What effect do successive cycles of menstruation have on breast tissues?
Produce more milk producing tissue within the breast causing increased growth
What is noticeable about the before menstruation?
There is increased volume
During pregnancy what hormones influence breast tissue growth and what are their functions?
Estrogen -Breast growth
Progesterone - induces side branching of ducts
Prolactin - alveolar development, stimulate casein and alpha lactalbumin mRNAs
Insulin and Cortisol - stimulate alveolar epithelial cell division (cells that are going to produce the milk)
In the ——- ——— gland the alveolar structures are relatively insignificant compared to the ducts.
Resting mammary
When does the breast weigh the most?
When it is lactating
In theory ——- should promote milk production but ——— does not occur until after birth.
This is because the steroids, particularly ———- seem to prevent major milk production.
———- is also a smooth muscle relaxant and prevents milk ———.
In theory prolactin should promote milk production but lactation does not occur until after birth.
This is because the steroids, particularly progesterone seem to prevent major milk production.
Progesterone is also a smooth muscle relaxant and prevents milk ejection
What hormone is produced in large amount in pregnancy, but falls at birth?
Prolactin
Where is prolactin secreted from?
The anterior pituitary if the hypothalamus
What stimulates the prolactin release from the pituitary?
How do we know this?
Neuroendocrine reflex
We know it’s a neuroendocrine reflex because cutting the nerves to the nipple prevents this reflex
What does prolactin induce?
The production of milk proteins.
——– of the infant on the nipple induces secretion of ——— by the —– —–.
The ——- and ——- of the ——– determines ——— secretion.
The level of ——— determines the level of —– produced. This means the baby is able to ——- the amount of ——- it gets.
Suckling of the infant on the nipple induces secretion of prolactin by the anterior pituitary.
The duration and extent of the suckling determines prolactin secretion.
The level of prolactin determines the level of milk produced. This means the baby is able to regulate the amount of food it gets.
Milk ejection response (MER)
—— stimulates the synthesis and secretion of ——- by the —— ——.
———- induces the contraction of the ——- cells of the ——– causing ejection of the —— into the —–.
This is called the —— —– response.
Suckling stimulates the synthesis and secretion of oxytocin by the posterior pituitary.
Oxytocin induces the contraction of the myoepithelial cells of the alveoli causing ejection of the milk into the ducts.
This is called the let down response.
What other stimuli can induce the release of oxytocin?
Stimulation of the female reproductive tract.
Why might a lactating women have a milk let down during sex?
This is because the stimulation of the cervix causes the release of oxytocin, which is important in causing uterine contractions to help sperm transport. But the same hormone causes the let down response
What are the stimuli that can induce the milk ejection response?
Suckling
Smell of the baby
crying baby
How does lactation affect fertility?
Prolactin can suppress secretion of the gonadotropins, FSH and LH, particularly LH (stimulates ovulation).
Therefore, lactating women often have no or irregular menstrual cycles.
So lactation has a contraceptive effect - spacing out the birth of babies
Not a very reliable contraceptive
What benifits does breastfeeding have on the mother?
Contraceptive effect - spacing out the birth of babies
There is a decreased relative risk of developing breast cancer and ovarian cancer
What benifits does breastfeeding have on the infant?
Babies are protected from getting GI tract infections, asthma, childhood obesity, type 1 and 2 diabetes and sudden infant death syndrome
If there is additional breast tissue where it is usually found?
Along the line of the embryonic milk ridge
Can lactiferous ducts exit the breast at sites outside the nipple?
Yes
