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НазваMammary gland (Endocrine system) (реферат)
АвторRoman
РозділІноземна мова, реферати англійською, німецькою
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Реферат на тему:

 

Mammary gland (Endocrine system)

 

 

Mammary glands are the HYPERLINK

"http://en.wikipedia.org/wiki/Organ_(anatomy)" \o "Organ (anatomy)"

organs that, in HYPERLINK "http://en.wikipedia.org/wiki/Mammal" \o

"Mammal" mammals , produce HYPERLINK

"http://en.wikipedia.org/wiki/Milk" \o "Milk" milk for the sustenance

of the young. These HYPERLINK

"http://en.wikipedia.org/wiki/Exocrine_gland" \o "Exocrine gland"

exocrine glands are enlarged and modified HYPERLINK

"http://en.wikipedia.org/wiki/Sweat_gland" \o "Sweat gland" sweat

glands and give mammals their name. The mammary glands of domestic

mammals containing more than two breasts are called dugs.

 

Humans

 

Structure

 

The basic components of the mammary gland are the alveoli (hollow

cavities, a few millimetres large) lined with milk-secreting HYPERLINK

"http://en.wikipedia.org/wiki/Cuboidal_cells" \o "Cuboidal cells"

cuboidal cells and surrounded by HYPERLINK

"http://en.wikipedia.org/wiki/Myoepithelial_cell" \o "Myoepithelial

cell" myoepithelial cells . These alveoli join up to form groups known

as lobules, and each lobule has a lactiferous duct that drains into

openings in the HYPERLINK "http://en.wikipedia.org/wiki/Nipple" \o

"Nipple" nipple . The myoepithelial cells can contract under the

stimulation of HYPERLINK "http://en.wikipedia.org/wiki/Oxytocin" \o

"Oxytocin" oxytocin thereby excreting the milk from glands through the

lactiferous ducts toward the nipple, where it collects in sinuses of the

ducts. As the infant begins to suck, the hormonally (oxytocin) mediated

"let down reflex" ensues and the mother's milk is secreted into – not

sucked from the gland by – the baby's mouth.

 

All the milk-secreting tissue leading to a single lactiferous duct is

called a "simple mammary gland"; a "complex mammary gland" is all the

simple mammary glands serving one nipple. Humans normally have two

complex mammary glands, one in each HYPERLINK

"http://en.wikipedia.org/wiki/Breast" \o "Breast" breast , and each

complex mammary gland consists of 10–20 simple glands. The presence of

more than two nipples is known as HYPERLINK

"http://en.wikipedia.org/wiki/Polythelia" \o "Polythelia" polythelia

and the presence of more than two complex mammary glands as HYPERLINK

"http://en.wikipedia.org/wiki/Accessory_breast" \o "Accessory breast"

polymastia .

 

Development and hormonal control

 

Mammary glands exist in both sexes, but are rudimentary until

HYPERLINK "http://en.wikipedia.org/wiki/Puberty" \o "Puberty" puberty

when, in females, they begin to develop in response to HYPERLINK

"http://en.wikipedia.org/wiki/Ovarian" \o "Ovarian" ovarian hormones.

HYPERLINK "http://en.wikipedia.org/wiki/Estrogen" \o "Estrogen"

Estrogen promotes formation, whereas HYPERLINK

"http://en.wikipedia.org/wiki/Testosterone" \o "Testosterone"

testosterone inhibits it.

 

At the time of HYPERLINK "http://en.wikipedia.org/wiki/Childbirth" \o

"Childbirth" birth , the baby has lactiferous ducts but no alveoli.

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