Mammalian Reproduction

Group 2

III - Rubidium

Keywords

glans penisHymenLeydig cellsmammary glandsmyotoniaoogenesisorgasmovariesoviduct/Fallopian tubesovulationpenisprepuce

prostate glandscrotumsemenseminal vesiclesseminiferous tubulesSpermatogenesistestisurethrauterusvaginavas deferensvasocongestion

acrosomebaculumBartholin’s glandsbulbourethral glandcervixclitoriscoituscorpus luteumejaculationendometriumepididymisfollicle

Human reproduction involves intricate anatomy

and complex behavior

Male reproductive system

External reproductive organs scrotumpenis

Internal reproductive organsgonads - produce gametes and hormonesaccessory glands - secrete products

essential to sperm movementducts - carry sperm and glandular

secretions

Testes male gonads seminiferous tubules

highly coiled tubes where sperm form Leydig cells

scattered between the seminiferous tubules produce testosterone and other androgens, which are the

male sex hormones.

Scrotum a fold of the body wall holds the testes of animals that are located outside of

the abdominal cavity

Epididymis bundle of coiled tubes it takes about 20 days for sperm to pass through the 6-m-

long tubules of each epididymis of a human male Here, sperm become motile and gain the ability to fertilize

Vas Deferens 2 muscular ducts. run from the scrotum around and behind the urinary

bladder, where each joins a duct from the seminal vesicle, forming a short ejaculatory duct.

Ejaculatory Duct mixes the sperm stored in the ampulla with fluids

secreted by the seminal vesicles transports these substances to the prostate.

Accessory Glands seminal vesicles prostate bulbourethral glands

Prostate Gland The largest semen-secreting gland. secretes its products directly into the urethra through

several small ducts.

Erectile Tissue The human penis is composed of three cylinders

of spongy erectile tissue derived from modified veins and capillaries.

Bulbourethral Glands A pair of small glands along the urethra below the

prostate Before ejaculation they secrete clear mucus that

neutralizes any acidic urine remaining in the urethra.

Prepuce Covers the human glans Also caled foreskin Removed during circumcision

Glans penis The head of the penis

Baculum A bone possessed by certain mammals, such as

rodents, raccoons, and walruses contained in, and helps stiffen, the penis

Female reproductive system

External reproductive structures: clitoris, two sets of labia (surrounds clitoris and

vaginal opening)

Internal reproductive structures:Pair of gonads system of ducts and chambers (carry

gametes and house the embryo and fetus)

Ovaries lie in abdominal cavityattached to uterus through a mesenteryenclosed in tough protective capsule and

contains plenty of follicles

Follicle an egg cell nourished and protected by one or

more layers of follicle cells surrounding it usually one follicle matures and releases its egg

cell during each menstrual cycle-produce estrogens (primary female sex hormones)

Ovulation the process by which an egg cell is released from

the follicle

corpus luteum ("yellow body") solid mass formed by remaining follicular tissue

that grew in the ovary secretes additional estrogen and progesterone

(hormone responsible for maintaining the uterine lining during pregnancy)

the corpeus luteum disintegrates when the egg cell is not fertilized

Oviduct (fallopian tube) funnel like opening cilia on the epithelium lining the duct help

collect the egg cell cilia also convey the egg down towards the

uterus (womb)

Uterus thick, muscular organ that expands during

pregnancy Endometrium

inner lining of the uterus, richly supplied with blood vessels

Cervix neck of the uterus

Mammary Glandspresent in both sexes, but functional only in

womennot part of reproductive systemhas small sacs of epithelial tissue that

secrete milk that are drained through ducts that lead to the nipple

Vagina a thin-walled chamber that forms the birth

canal through which the baby is born; it is also the repository for sperm during copulation

Vulva the region of external genital organs.

Hymena vascularized membrane that partly covers

the vaginal opening in humans

Vestibule where the vaginal and separated urethral

openings are located

Labia Minora is composed of a air of slender skin folds

which borders the vestibule

Labia Majora is a pair of thick and fatty ridges, which

encloses and protects the labia minora and the vestibule

Clitoris found at the front end of the vestibule, it

consists of a short shaft supporting a rounded glands, covered by a small hood of skin, the prepuce. It is one of the most sensitive points of sexual stimulation

Bartholin's Glands located near the vaginal opening, which

secrete mucus into the vestibule, keeping it lubricated and facilitating intercourse

Human Sexual Response

2 Types of Physiological Reactions 1. Vasocongestion

filling of a tissue with blood caused by increased blood flow in arteries in that tissue

causes the hardening of penis during erection Causes the hardening of the clitoris and vaginal

lubrication other forms of vasocongestion:

blushing, swelling of nipples during sexual arousal

2. Myotonia increased muscle tension in both skeletal

and smooth muscleboth skeletal and smooth muscle may show

sustained or rhythmic contractions including those associated with orgasm

Sexual Response Cycles

Phase 1 - ExcitementPrepares vagina and penis for coitus, or

sexual intercourse vasocongestion is evident in:

erection of penis and clitoris enlargement of the testes, labia, and breasts vaginal lubrication

myotonia may occur resulting in nipple erection tension in the arms and legs

Phase 2 - Plateau continues responses from excitement

phasebreathing increasesheart rate increasesheart rate rises up to 150 bpm as an

involuntary response to stimulation of autonomic nervous system

Phase 2 - Plateau in males:

urinary bladder closes (to prevent urine from mixing with semen, and guard against retrograde ejaculation)

muscles at the base of the penis begin a steady rhythmic contraction.

males may start to secrete seminal fluid or pre-ejaculatory fluid 

Testicles rise closer to the body

Phase 2 - Plateau in females:

outer third of vagina becomes vasocongested inner two-thirds becomes slightly expanded uterus is elevated forms depression that receives sperm at the

back of vagina

Phase 3 - Orgasm characterized by rhythmic, involuntary

contractions of the reproductive structures in both sexes

shortest phase of sexual response cycle

Phase 3 - Orgasm in males - 2 stages:

Emission – contraction of the glands and ducts of the reproductive tract which forces semen into the urethra

Expulsion or ejaculation – occurs when urethra contracts and semen is expelled

In females uterus and outer vagina contract, but the inner

two-thirds of the vagina do not

Phase 3 - Orgasm in both sexes, contractions occur at about

0.8-sec intervals and may involve the anal sphincter and several abdominal muscles

Phase 4 - Resolution completes the cycle and reverses the responses of

the earlier stages vasocongested organs return to normal size and

color, and muscles relax most of the changes during resolution are

completed in 5 minutes loss of penile and clitoral erection may take longer

Structure of the sperm cell

Head

Acrosome

helps penetrate the egg cells with its enzymes

Nucleus

Centriole

Middle piece

contains large amounts of mitochondria that provide ATP for movement of the tail

Tail

Structure of the egg cell

Corona radiata

covering that supply vital

proteins to the cell

Zona pellucida

binds spermatozoa

required to initiate the acrosome reaction

used for protection.

very essential for the oocyte’s death and fertilization

Nucleolus

non-membrane bound structure made of protein and nucleic acid and transcribes RNA.

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