Human Human ReproductionReproduction

Objectives:Objectives:

1.1. To identify the anatomy of the Male To identify the anatomy of the Male Reproductive SystemReproductive System

2.2. To understand the hormonal To understand the hormonal controls in sperm productioncontrols in sperm production

3.3. To identify the anatomy of the To identify the anatomy of the Female Reproductive SystemFemale Reproductive System

4.4. To understand the hormonal To understand the hormonal controls involved in the 4 stages of controls involved in the 4 stages of the Menstrual Cycle the Menstrual Cycle

Let’s CompareLet’s Compare

Male System – simple!Male System – simple! Female System – Female System – complicated !!complicated !!

Let’s look at the Male System first.Let’s look at the Male System first. All it does is produce 2-4 million All it does is produce 2-4 million

sperm cells per day starting at sperm cells per day starting at puberty and continuing until the puberty and continuing until the day you die!day you die!

Male AnatomyMale Anatomy

Cross-section of the Cross-section of the Seminiferous Tubule Seminiferous Tubule

Anatomy of the Anatomy of the Seminiferous TubuleSeminiferous Tubule

SpermatagoniaSpermatagonia – 2n reproductive cells – 2n reproductive cells that undergo meiosis to produce that undergo meiosis to produce haploid sperm cellshaploid sperm cells

Interstitial Cells Interstitial Cells – Produce – Produce testosteronetestosterone

Sertoli Cells Sertoli Cells – provide nourishment – provide nourishment for the developing sperm cellsfor the developing sperm cells

Endocrine SystemEndocrine System

Hormonal Control of Sperm Hormonal Control of Sperm ProductionProduction

It all starts in your…..BRAIN!!It all starts in your…..BRAIN!! The The HypothalamusHypothalamus secretes many secretes many

hormones into your blood including hormones into your blood including GnRH GnRH which stimulates the which stimulates the PituitaryPituitary to to secrete 2 hormones called: secrete 2 hormones called: FSH – FSH – Follicle Stimulating Hormone Follicle Stimulating Hormone LH – Lutenizing HormoneLH – Lutenizing Hormone

FSH – stimulates sperm productionFSH – stimulates sperm production LH – stimulates testosterone production LH – stimulates testosterone production

TestosteroneTestosterone Promotes more sperm production AND Promotes more sperm production AND

the development of secondary sex the development of secondary sex characteristicscharacteristics

Negative FeedbackNegative Feedback As levels of testosterone rise the As levels of testosterone rise the

hypothalamus detects the levels and……hypothalamus detects the levels and…… ……stops the production of GnRH which……stops the production of GnRH which…… ……stops the production of LH which……..stops the production of LH which…….. ……reduces the production of testosterone reduces the production of testosterone This is called This is called Negative FeedbackNegative Feedback

Hormonal FeedbackHormonal Feedback

Hypothalamus

Negative feedback

Testosteroneproduction

Releasinghormone

Anteriorpituitary

FSH

LH

Spermproduction

Positive feedbackPositive feedback

As dropping testosterone levels are As dropping testosterone levels are detected, the _____________ starts to detected, the _____________ starts to release ___________, which causes the release ___________, which causes the __________gland to release __________gland to release ____________, which increases the ____________, which increases the production of ______________.production of ______________.

This is called This is called Positive FeedbackPositive Feedback

Sperm CellsSperm Cells

SemenSemen Semen, not to be confused with “seaman”, Semen, not to be confused with “seaman”,

is the fluid that sperm cells swim in.is the fluid that sperm cells swim in. There are three glands that secrete the There are three glands that secrete the

fluids:fluids: Prostate gland – secretes an alkaline buffer Prostate gland – secretes an alkaline buffer

that neutralizes the acidic environment of the that neutralizes the acidic environment of the vagina.vagina.

Seminal vesicles – secrete a fructose solution Seminal vesicles – secrete a fructose solution that provides energy for the sperm cellsthat provides energy for the sperm cells

Cowper’s gland – secretes a mucous that lines Cowper’s gland – secretes a mucous that lines the urethra to prevent the sperm from the urethra to prevent the sperm from contacting any urine residuecontacting any urine residue

Female AnatomyFemale Anatomy

It all starts in the Brain It all starts in the Brain (again)!(again)!

Menstrual CycleMenstrual Cycle

28 day cycle that begins at puberty 28 day cycle that begins at puberty and continues until menopauseand continues until menopause

Consists of 4 stages:Consists of 4 stages: Menstruation (your period)Menstruation (your period) Follicle StageFollicle Stage OvulationOvulation Corpus Luteum StageCorpus Luteum Stage

#1 Menstruation#1 Menstruation

4-6 days4-6 days EndometriumEndometrium and unfertilized egg and unfertilized egg

are removed from the uterus.are removed from the uterus. Pituitary gland releases Pituitary gland releases FSHFSH which which

stimulates the follicles in the stimulates the follicles in the ovaries.ovaries.

Ovary and FolliclesOvary and Follicles

#2 Follicle Stage#2 Follicle Stage

One follicle usually “becomes the One follicle usually “becomes the chosen one” and continues to enlarge.chosen one” and continues to enlarge.

The ovaries release The ovaries release EstrogenEstrogen Rising levels of Rising levels of Estrogen Estrogen send negative send negative

feedback to the Pituitary stopping the feedback to the Pituitary stopping the production of production of FSH FSH and positive and positive feedback initiating the release of feedback initiating the release of LH. LH.

Estrogen Estrogen causes the endometrium to causes the endometrium to thickenthicken

#3 Ovulation#3 Ovulation

Around day 14, Around day 14, LHLH levels are at their levels are at their highest and cause the stimulated highest and cause the stimulated follicle to rupture and release it’s follicle to rupture and release it’s egg.egg.

The egg is swept by the fimbria into The egg is swept by the fimbria into the oviductthe oviduct

You are most vulnerable to You are most vulnerable to becoming pregnant!becoming pregnant!

#4 Corpus Luteum Stage#4 Corpus Luteum Stage

The ruptured follicle changes into a The ruptured follicle changes into a yellowish structure called the yellowish structure called the Corpus Luteum.Corpus Luteum.

It releases It releases estrogenestrogen and and progesterone (progesterone (pregnancy hormonepregnancy hormone) )

If pregnancy results:If pregnancy results: Estrogen and progesterone levels stay Estrogen and progesterone levels stay

high, preventing the release of FSH by high, preventing the release of FSH by the pituitary (NF) the pituitary (NF)

Corpus Luteum StageCorpus Luteum Stage

#4 Corpus Luteum Stage#4 Corpus Luteum Stage

If pregnancy does not occur:If pregnancy does not occur: Estrogen and progesterone levels drop, Estrogen and progesterone levels drop,

causing the endometrium to deteriorate causing the endometrium to deteriorate and menstruation begins again. and menstruation begins again.

Dropping levels of estrogen and Dropping levels of estrogen and progesterone cause the pituitary to progesterone cause the pituitary to begin releasing FSH (PF) begin releasing FSH (PF)

Review of the Menstrual Cycle

Birth Control PillsBirth Control Pills Trick your body into thinking it is Trick your body into thinking it is

pregnant.pregnant. If your body thinks it is pregnant, you If your body thinks it is pregnant, you

won’t ovulate.won’t ovulate. Without an egg being released, you cannot Without an egg being released, you cannot

become pregnant. become pregnant. Each pill has different amounts of Each pill has different amounts of

progesterone.progesterone. The “pill” can be prescribed to regulate The “pill” can be prescribed to regulate

your period because of the specific levels your period because of the specific levels of hormones found in each pill of hormones found in each pill

Pregnancy TestsPregnancy Tests

Check for the presence of hCG Check for the presence of hCG (Human Chorionic Gonadotrophin) (Human Chorionic Gonadotrophin) in the mother’s urinein the mother’s urine

The fertilized egg releases hCGThe fertilized egg releases hCG

Terms to remember:Terms to remember:

Fertilization – union of egg and sperm inside Fertilization – union of egg and sperm inside the oviduct. the oviduct. Fertilization and Implantation

Implantation – attachment of fertilized egg Implantation – attachment of fertilized egg into the endometrium 6 to 8 days after into the endometrium 6 to 8 days after fertilization.fertilization.

Gastrulation – 16 to 18 days after fertilizationGastrulation – 16 to 18 days after fertilization Embryo – term used to refer to the developing Embryo – term used to refer to the developing

ball of cells after gastrulation up to 8 weeks.ball of cells after gastrulation up to 8 weeks. Fetus – after 8-10 weeks Fetus – after 8-10 weeks Make Room For the Baby

4 weeks4 weeks5 months5 months

8 months8 months

Embryological Embryological DevelopmentDevelopment