Mammalian Reproduction

GERONIA rey || MABUNGA ronnMACINAS ian || MALONZO dindo

MATANGUIHAN joem || MATUBA sam REYES yves || SALAZAR carl

SAN PEDRO victor || BAUTISTA denise

III - Rb

Male Reproductive System

Male Reproductive System

Female Reproductive System

Female Reproductive System

Human Sexual Response

Two types of physiological reactions predominate in both sexes:vasocongestion – filling of a tissue with

blood due to increase blood flowmyotonia – increased muscle tension

Human Sexual Response

Four phases:ExcitementPlateauOrgasmResolution

Excitement

Preparation of vagina and penis for coitusVasocongestion is evident in the penis

and clitorisEnlargement of the testes, labia, and

breastsVaginal lubricationMyotonia may occur, eg., nipple erection

and tension of arms and legs

Plateau

Outer third of the vagina becomes vasocongested, inner two thirds slightly expanded

Breathing increases and heart rate rises (up to 150 beats per minute) as a response to stimulation of autonomic nervous system

Orgasm

Rhythmic, involuntary contractions of the reproductive structures

Males: emission and expulsion/ejaculationShortest phase, lasting only a few

secondsContractions occur at 0.8-sec intervals

Resolution

Vasocongested organs return to normal size and color

Muscles relaxMost changes happen in 5 minutesPenile and clitoral erection may take

longer to return to normal size and color

Human Sexual Response

“Sex could kill you. Do you know what the human body goes through when you have sex? Pupils dilate, arteries constrict, core temperature rises, heart races, blood pressure skyrockets, respiration becomes rapid and shallow, the brain fires bursts of electrical impulses from nowhere to nowhere, and secretions spit out of every gland, and the muscles tense and spasm like you're lifting three times your body weight. It's violent, it's ugly and it's messy, and if God hadn't made it unbelievably fun, the human race would have died out eons ago.”

- Cameron (House MD, Season 1, Occam’s Razor)

The Sperm

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Mak

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The Egg

Oogenesis – making of eggs

Ovulation

Two phases in the ovarian cycleFollicular phaseLuteal phase

Follicular Phase

Several follicles begin to growEgg cells enlarge; coat of follicles become

multilayeredOnly one follicle grows, others dieMaturing follicle develops an internal fluid-

filled cavity and grows very largeEnds with ovulation, the release of the

egg cell from the follicle

Luteal Phase

Remaining follicular tissue develops into the corpus luteumCorpus luteum – endocrine tissue that secretes

female hormones during the phase

Hormonal Control

Gonadotropin-releasing hormones (GnRH)Released by the hypothalamusStimulates production of FSH and LH in the

anterior pituitary

Follicle-stimulation hormone (FSH)Stimulates formation of follicles in the ovaries

Luteinizing hormone (LH)Stimulates remaining follicular tissue after

ovulation to form the corpus luteum

Hormonal Control

During the follicular phase:GnRH stimulates production of FSH and LHFSH stimulates follicle growthGrowing follicles release estrogensSmall increase in estrogens inhibit secretion of

FSH and LHHigh concentration of estrogens stimulates the

secretion of FSH and LH by triggering the production of GnRH

Hormonal Control

Increase in LH stimulated by increase in estrogens stimulates maturation of the follicle

(positive feedback)Ovulation occurs a day after the LH surge

Hormonal Control

During the luteal phase:LH stimulates transformation of follicular tissue

into the corpus luteumCorpus luteum secretes estrogens and

progesteroneIncrease in estrogens and progesterone cause

negative feedback on the hypothalamus and pituitary, inhibiting secretion of FSH and LH

Hormonal Control

Disintegration of corpus luteum causes a decline in estrogens and progesterone

This in turn liberates the hypothalamus and pituitary from the inhibitory effects of these hormones

Ovulation

Menstrual vs. Estrous

In both cases, ovulation occurs after the endometrium has started to thicken

In menstrual cycles, the endometrium is shed in a bleeding called menstruation

In estrous cycles, the endometrium is reabsorbed by the uterus; no extensive bleeding occurs

Menstrual vs. Estrous

Estrous cycles include more pronounced behavioral changes and stronger effects of season and climate

Estrus (L. oestrus, “frenzy”, “passion”)Period of sexual activityVaginal changes during this period permits

mating

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