http:

http://www.youtube.com/watch?v=WGJsrGmWeKE&feature=related

Male Reproductive Hormones

1. androsterone

2. testosterone

Seminal vesicle

(Rectum)

Vas deferens

Ejaculatory duct

Prostate gland

Bulbourethral gland

(Urinarybladder)

(Pubic bone)

Erectiletissue of

penis

Urethra

Glans penis

Prepuce

Vas deferens Epididymis

Testis

Scrotum

Erectile tissueof penis

Prostate gland

(Urinarybladder)

Bulbourethral gland

Vas deferensEpididymisTestis

Seminalvesicle(behind bladder)

Urethra

Scrotum

Glans penis

Male Reproductive Hormonesboth hormones are released from testes

Testes Cells1. Leydig interstitial cells synthesize hormones

(between seminiferous tubules)

2. Sertoli cells synthesize sperm within seminiferous tubules

Testosterone Rolestimulates spermatogenesis (production of mature

sperm cells) – life time process

develops male characteristics at puberty

Gonadotropic Hormones gonadotropic hormones regulate gonad

development (male and female) produced in the anterior pituitary; released upon

hypothalamus signal

1. follicle stimulating hormone (FSH)

2. luteinizing hormone (LH)

Male Gonad Development1. Hypothalamus secretes gonadotropin-

releasing hormone (GnRH)

2. Anterior pituitary gland releases FSH & LH

3. FSH stimulates Sertoli cells to form mature sperm

4. LH stimulates Leydig cells to secrete testosterone

Male Gonad Development

Role of testosterone:

1. promotes Sertoli cell activity - increases sperm cell production

2. negative feedback on hypothalamus - inhibits the hypothalamus by decreasing the secretion of FSH and LH from the anterior pituitary gland

To Much TestosteroneStronger sex drive

may lead to risky behaviours

More impulsive and more aggressive

Mood changes irritability and depression

Stimuli from otherareas in the brain

Hypothalamus

GnRH from thehypothalamus reg-ulates FSH and LH

release from theanterior pituitary.

FSH acts on theSertoli cells of the

seminiferoustubules, promotingspermatogenesis.

LH stimulates the Leydig cells to maketestosterone, whichin turn stimulatessperm production.

Anteriorpituitary

Negativefeedback

Leydig cellsmake

testosterone

Primary andsecondary sexcharacteristics

Sertoli cells

Spermatogenesis TestisFigure 46.14

If testosterone levels get too

high

Female Reproductive System

1. estrogen

2. progesterone

Female Reproductive Systemboth produced in the ovaries

Vagina

Uterus

Cervix

OvariesOviduct

Uterine wallEndometrium

Follicles

Corpus luteum

Female Reproductive Systemcomparatively more complicated than male

reproductive systemEach ovary contains about 400,000 follicles at pubertyOnly about 400 eggs will mature and go through

ovulation throughout a woman’s lifeMonthly cycle until menopause (~12 x 50 yrs) = 400-

450 cycles

female hormones responsible for oogenesis (development of mature egg cells) and ovulation

Ovary Follicle Cells1. primary oocyte fertilized by sperm

2. granulosa cells provide nutrients for primary oocyte

Female Gonad Development GnRH, FSH and LH involved

1. Hypothalamus secretes gonadotropin-releasing hormone (GnRH)

2. Anterior pituitary gland releases FSH & LH

3. FSH matures follicle

4. LH causes ovulation and causes corpus luteum maturation

Menstrual/Ovarian Cycle

Menstrual Cycle

1. menstruation (flow phase) Shedding of the endometrium Occurs only if there is no ovum fertilization estrogen and progesterone levels low

2. follicular phase Development of follicles estrogen secretion by granulosa cells Estrogen signals the endometrium to thicken

Menstrual Cycle3. ovulation

ovum leaves ovary granulosa cells

become corpus luteum

corpus luteum begins to secrete progesterone

estrogen levels start to decrease

Figure 46.15a, b

Ovary

Uterus

Endometrium

From ovulation to implantation

Endometrium Inner cell mass

Cavity

BlastocystTrophoblast

(a)

Implantation of blastocyst(b)

Menstrual Cycle

4. luteal stagecorpus luteum secretes progesterone & small amount of

estrogenprogesterone encourages endometrium development for

embryoIf no fertilization occurs = no embryo

corpus luteum degenerates after about 10 days and produces a scar (corpus albicans)

Concentrations of estrogen and progesterone decrease Causing weak uterine contractions (marking the beginning

of the flow phase)

http://www.youtube.com/watch?v=WGJsrGmWeKE&feature=related

Can a female get pregnant before she has had her first period?YES!By the time she has reached

puberty 400,000 follicles (no Corpus Luteum)Hypothalamus GnRHAP FSH, LHFSH induces

development of follicles

Ovulation occurs before menstruation!

What regulates the events of the menstrual/ovarian cycle?

Varying levels of LH and FSH determined by varying levels

of estrogen and progesterone

Many different positive and negative feedback mechanisms involved

1. Follicular Phase Low level of estrogen

inhibits production of LH and FSH (keeping their levels low)

Inhibits AP to prevent ovulation

2. Ovulation High estrogen stimulates

LH and FSH production (more effect on LH than FSH)

Stimulates AP to cause ovulation

3. Luteal Phase High levels of

progesterone and estrogen inhibits LH and FSH production

Inhibit AP and Hypothalamus

1

2

1

2

3

3

Menopause

ovaries lose responsiveness to FSH and LH

usually occurs between ages 46 and 54

most other mammals do not undergo menopausethought to allow human females to take care of

grandchildren rather than continue to reproduce

Man-opause?Andropause male menopause

Decreased levels of testosteroneSex drive decreasedIncrease in memory lossBreast enlargementBody composition = more fat, less muscle

More fat = more testosterone is converted to estrogen

In class workLab Exercise 8.5.1 (Hormone Levels During

the Menstrual Cycle)

HomeworkSection 8.5 – Page 399 #1—5,7-13