lesson 33

It is somewhat pear-shaped, with a broad superior curvature
called the fundus, a midportion called the body (corpus), and
a narrow inferior end called the cervix

The lumen communicates with the
vagina by way of a narrow passage through the cervix called the cervical
canal. The superior opening of this canal into the body of the
uterus is the internal os42 (pronounced “oss”), and its opening into the
vagina is the external os.

shortening of the uterine cervix and thinning of its walls as it is dilated during labor

is the opening of the cervix, the entrance to the uterus

this passage leads from the opening of the vulva to the uterus (womb), but the vaginal tract ends at the cervix

diamond-shaped region between the thighs. The perineum is bordered by four
bony landmarks: the pubic symphysis anteriorly, the coccyx posteriorly, and the ischial tuberosities laterally.

At the vaginal orifice, the mucosa folds inward and forms a
membrane, the hymen, which stretches across the opening. The
hymen has one or more openings to allow menstrual fluid to pass,
but it usually must be ruptured to allow for intercourse.

line that extends from perineum to anus

The external genitalia of the female occupy most of the perineum,
and are collectively also known as the vulva

consists mainly of an
anterior mound of adipose tissue overlying the pubic symphysis,
covered with skin and bearing pubic hair

are a pair of thick folds of skin and adipose tissue
inferior to the mons, between the thighs, Pubic hair grows on the lateral surfaces of the
labia majora at puberty, but the medial surfaces remain hairless

Medial to the labia majora are the much thinner, entirely hairless

the area enclosed by the labia minora, contains the urinary and vaginal orifices.

At the
anterior margin of the vestibule, the labia minora meet and form a
hoodlike prepuce over the clitoris.
The clitoris is structured much like the penis in many respects,
but has no urinary role. Its function is entirely sensory, serving as
the primary center of erotic stimulation. Unlike the penis, it is almost
entirely internal, it has no corpus spongiosum, and it does
not enclose the urethra. Essentially, it is a pair of corpora cavernosa
enclosed in connective tissue.

the glans of the penis and clitoris develop from a
single embryonic genital tuber

A system of internal chemical
communication composed of all endocrine
glands and the hormone-secreting cells found in
other tissues and organs

A ductless gland
that secretes hormones into the bloodstream; for
example, the thyroid and adrenal glands.

A chemical messenger that is secreted
into the blood by an endocrine gland or isolated
gland cell and triggers a physiological response in
distant cells with receptors for it

have endothelial cells riddled with
holes called filtration pores (fenestrations4) (fig. 21.6). These
pores are about 20 to 100 nm in diameter, and are often
spanned by a thin glycoprotein membrane. They allow for the
rapid passage of small molecules but still retain most proteins
and larger particles in the bloodstream. Fenestrated capillaries
are important in organs that engage in rapid absorption or
filtration—the kidneys, endocrine glands, small intestine, and
choroid plexuses of the brain, for example

Cells of an organ that are affected or stimulated by specific hormones.

The milk-secreting gland that
develops within the breast in pregnancy and
lactation; only minimally developed in the breast
of a nonpregnant or nonlactating woman.

A gland that secretes
its products into another organ or onto the body
surface, usually by way of a duct; for example,
salivary and gastric glands

top part of breast

bottom part of breast

When the mammary gland develops during pregnancy, it exhibits
15 to 20 lobes arranged radially around the nipple, separated
from each other by fibrous stroma. Each lobe is drained by a lactiferous55
duct, which dilates to form a lactiferous sinus opening
onto the nipple.

The nipple is surrounded by a circular colored zone, the areola.
Dermal blood capillaries and nerves come closer to the surface here
than in the surrounding skin and make the areola more sensitive
and more reddish in color. In pregnancy, the areola and nipple often
darken,

which dilates to form a lactiferous sinus opening
onto the nipple. Internally, this duct branches repeatedly with the
finest branches ending in secretory acini. The acini are organized
into grapelike clusters (lobules) within each lobe of the breast. Each
acinus consists of pyramidal secretory cells arranged around a central
lumen, and a network of contractile myoepithelial cells around
the secretory cells