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The breasts

Whereas the breasts are located far from the other female reproductive organs, they are considered accessory organs of the female reproductive system. The function of the breasts is to supply milk to an infant in a process called lactation. The external features of the breast include a nipple surrounded by a pigmented areola    ( [link] ), whose coloration may deepen during pregnancy. The areola is typically circular and can vary in size from 25 to 100 mm in diameter. The areolar region is characterized by small, raised areolar glands that secrete lubricating fluid during lactation to protect the nipple from chafing. When a baby nurses, or draws milk from the breast, the entire areolar region is taken into the mouth.

Breast milk is produced by the mammary glands    , which are modified sweat glands. The milk itself exits the breast through the nipple via 15 to 20 lactiferous ducts    that open on the surface of the nipple. These lactiferous ducts each extend to a lactiferous sinus    that connects to a glandular lobe within the breast itself that contains groups of milk-secreting cells in clusters called alveoli    (see [link] ). The clusters can change in size depending on the amount of milk in the alveolar lumen. Once milk is made in the alveoli, stimulated myoepithelial cells that surround the alveoli contract to push the milk to the lactiferous sinuses. From here, the baby can draw milk through the lactiferous ducts by suckling. The lobes themselves are surrounded by fat tissue, which determines the size of the breast; breast size differs between individuals and does not affect the amount of milk produced. Supporting the breasts are multiple bands of connective tissue called suspensory ligaments    that connect the breast tissue to the dermis of the overlying skin.

Anatomy of the breast

This figure shows the anatomy of the breast. The left panel shows the front view and the right panel shows the side view. The main parts are labeled.
During lactation, milk moves from the alveoli through the lactiferous ducts to the nipple.

During the normal hormonal fluctuations in the menstrual cycle, breast tissue responds to changing levels of estrogen and progesterone, which can lead to swelling and breast tenderness in some individuals, especially during the secretory phase. If pregnancy occurs, the increase in hormones leads to further development of the mammary tissue and enlargement of the breasts.

Hormonal birth control

Birth control pills take advantage of the negative feedback system that regulates the ovarian and menstrual cycles to stop ovulation and prevent pregnancy. Typically they work by providing a constant level of both estrogen and progesterone, which negatively feeds back onto the hypothalamus and pituitary, thus preventing the release of FSH and LH. Without FSH, the follicles do not mature, and without the LH surge, ovulation does not occur. Although the estrogen in birth control pills does stimulate some thickening of the endometrial wall, it is reduced compared with a normal cycle and is less likely to support implantation.

Some birth control pills contain 21 active pills containing hormones, and 7 inactive pills (placebos). The decline in hormones during the week that the woman takes the placebo pills triggers menses, although it is typically lighter than a normal menstrual flow because of the reduced endometrial thickening. Newer types of birth control pills have been developed that deliver low-dose estrogens and progesterone for the entire cycle (these are meant to be taken 365 days a year), and menses never occurs. While some women prefer to have the proof of a lack of pregnancy that a monthly period provides, menstruation every 28 days is not required for health reasons, and there are no reported adverse effects of not having a menstrual period in an otherwise healthy individual.

Questions & Answers

what is metabolism
fred Reply
Chemical reaction that takes in place in the cell of a living organism that includes anabolism and Catobolism.
Norman
Catabolism*
Norman
metabolic chemical reaction is of two types, anabolism and catabolism. The break down of larger molecules into smaller molecules is called catabolism.
Ahmad
Metabolism is the chemical reaction that includes anabolism and catabolism
Kedha's
Anabolism is the chemical reaction that combines all the smaller quantities to make large
Kedha's
Catabolism is the chemical process that breaks larger quantities into small
Kedha's
what's abdominal police?
Mohamed
hcl
Annette
hydrochloric acid is the stomach police
Annette
its the stomach omentum
Agama
description of the ears
Nana Reply
which component of mucus allows it to maintain local level of hydration
Loriann Reply
can the teeth be classify under bones?
Ojaga Reply
Bony prominents
guka
What is the largest muscle in the lower leg
Gwen Reply
what's a nervous system
Dante Reply
Is a the group of neurons and glial cells that work together to receive, integrate and responds appropriately to stimulus in the periphery, spinal cord and brain.
Hertzo
study about internal structure, outer structure and their functions
Navdeep Reply
circulatory system on blood pressure
Lakhu Reply
What is ELISA
POULAMI Reply
(enzyme linked immunosorbent assay) is a test that uses antibodies and color change to identify a substance.
luke
tr
Mohamed
what's defense mechanism?
Saintina
psychological strategies that are unconsciously used to protect a person from anxiety arising from unacceptable thoughts or feelings.
Henry
difference between apocrine sweat glands and merocrine sweat glands
Binkheir Reply
I believe the apocrine sweat gland uses a sac under the hair follicle and the merocrine sweat gland releases directly on to the surface of the skin
Mark
normal blood volume in our body
pankaj Reply
5Litres
Albert
Normal blood volume in adults is 6 litres
Kedha's
4.7 to 5ltr.. normal for adult
Clangbhelle
what are the advantages of the concave shape of red blood cells?
Amy Reply
This structure is VERY flexible. It can allow these cells to get into the most tiny places in our bodies. a VERY good design! The advantage of red blood cells' biconcave shape is that the surface area is increased to allow more haemoglobin to be stored in the cell.
Saafi
They can stack so that they can move to capillaries
Nejat
what is the difference between phagocytosis and Pinosis
fred
action of gluteus medius and minimus
Green Reply
Lateral rotation of the hip joint
Hertzo
Briefly explain location of ecg on a patient
Prince Reply
it is a machine that gives a graphical representation of heart beat
Nani
Briefly explain location of ecg leads on a patient?
Prince
in ecg we use electrical leads over the chest ,ancle and wrist
Nani
what is the anatomical and function difference between paravertebral and prevertebral ganglia ?
Rada Reply

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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