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TRANSCRIPT
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