Lecture #11 Flashcards
Define biparental and Gametes
Biparental- means offspring receive genes from two parents
Gametes - sex cell produced by each parent
Gametes are combined to form a?
zygote (or a fertilized egg)
Sperm
- has motility
- parent with Y chromosome is male
- produced in testes
Egg (ovum)
- female parent, lacking Y chromosomes
Male reproductive system’s Purpose
produce sperm and introduce them into the female body
Female reproductive system’s purpose
produce eggs, receive sperms, provide gametes’ union, carries fetus, and nourishes offspring
Puberty
-occurs during the first few years of adolescence
maked by periods in girls at age 12
and ejectulation in boys age 14
Physical Characteristics of Puberty
- Growth of sex organs
- Testosterone stimulates generalized body growth
- Erythropoiesis, basal metabolic rate, and increase in appetite
- Pubic hair, axillary hair, and facial hair develop in response to
dihydrotestosterone (DHT) - Stimulates sperm production and libido (sex drive)
What is GnRH
as hypothalamus matures it produces GnRH, which stimulates the anterior pituitary cells to secrete
1) FSH
2) LH
FSH
Follicle-stimulating hormone responsible for stimulating sustentacular cells that secrete androgen-binding protiens that bind to testosterone (stimulates spermatogenesis)
LH
Luteinizing Hormone (LH:) stimulates interstitial cells in testes to produce testosterone
Spermatogenesis
process of sperm production in seminiferous tubules of testes
If a male animal is castrated would you expect the FSH and LH levels to rise, fall, or be unaffected
levels to rise because the testes are removed because testosterone is none longer there so the negative feedback loop isn’t there
What does Testosterone do?
- sustains the male reproductive tract
- sperm production
- sex drive (libido)
- testosterone secretion decline with age
What is male andropause (climacteric)
- declining reproduction
- drop in testosterone and inhibin triggers rise in FSH and LH
mood changes and hot flash
Mitosis
one parent cell produce 2 daughter cells that are genetically the same
Meiosis
duplication and crossing over of genetic information
Spermatogenesis
spermatogonia lie along periphery of seminiferous tubules and is divided by mitosis
Type A spermatogonium
one daughter cell of each division remains in the tubule as stem cell
Type B Spermatogonium
other daughter cell migrate away from wall and is on its way to producing sperm
- becomes a primary spermatocyte, undergoes mitosis which gives rise to two secondary spermatocytes, then undergoes meiosis II dividing into two spermatids
Sperm Head Contains
A head:
- nucleus (haploid set of chromosomes)
- Acrosomes - enzyme cap that contains enzymes that penetrates the egg
Sperm Tail contains
- Mitochondria (in mid piece)
- Axoneme (flagella)
Seminal Fluid
90% of fluid expelled during orgasm
- water
- lubricant: mucus
- Buffers: neutralizers and nutrients
- Prostaglandin: smooth muscle contraction
Puberty in Females
- triggered by an increase of GnRH, which stimulates anterior pituitary FSH and LH
Eggs are stored in
the follicles within the ovary
FSH stimulation in Females
FSH stimulates ovarian follicles and they secrete estrogen, progesterone, inhibin, and androgen
Stages of Puberty
- Thelarche - breast development, earliest signs of puberty
- Pubarche - apperance of pubic and axillary hair, sebaceous glands, and axillary g;ands
- Menarche - first menstrual period, dependent on body fat
Climacteric
- midlife change in hormone secretion
- begins when 1000 follicles left
- cholesterol levels increase
- skin becomes thinner
- bone mass decreases
Menopause
cessation of menstrual cycles
- 45-55
- Menopause is considered complete once there is no menstruation for 1 year
Hormone Replacement Therapy (HRT)
low doses of estrogen and progesterone to relieve some of these symptoms
- risks and benefits still being debated
What is Oogenesis
is egg production
- produces haploid gametes by meiosis
- release 1 egg each month
Ovarian Cycle
three principals steps
- follicular phase, ovulation, and luteal (after ovulation) phase
whats left over is corpus luteum is progesterone and estrogen
Control of Ovulation by pituitary and ovarian hormones
POSITIVE FEEDBACK LOOP
1) maturing follicle secretes estradiol
2) Estradiol stimulates hypothalamus and anterior pituitary
3) Hypothalamus secretes GnRH
4) GnRH and estradiol stimulate pititary to secrete LH and FSH
5) Occytes completes meiosis I: follicel rapidly enlarges and then ovulates
What is Endometriosis
Growth of endometrial tissue outside of the uterus
- growth peritoneum of pelvic cavity or on surface of ovary
- occurs in 6-10% of women
- causes pain, sometimes infertility
- result from retrograde menstruation (backward flow of menstrual fluid that exits uterine tube)
Contraception
Birth Control Pills:
- Maintain high blood levels of estrogen/progesterone which inhibits release of FSH
- most popular among women
- also indicated for amenorrhea (no menstruation) and dysmenorrhea (painful menstruation)
Fertility Drugs
1) Clomiphere
- Estrogen Receptor Antagonist
- Stimulates release of FSH, LH and ovulation
2) Gonadotropin (FSH)
- extracted from postmenopausal urine
- stimulates follicles to mature and rupture
Define Conceptus:
all products of conception: the embryo or fetus, the placenta, and associated membranes
Prenatal Development
Blastocyst: the developing individual is a hollow ball for the first 2 weeks
Embryo: day 16 - week 8
Fetus: week 9-birth
Neonate: newborn -6weeks
What are the hormones with the strongest influence on pregnancy?
- Human Chorionic Gonadotropin (hCG)
- Estrogens
- Progesterone
- Human chorionic somatomammotropin
These hormones are secreted by the placenta
Terminated Pregnancy
Corpus luteum is important source for first several weeks, if its removed before week 7 the pregnancy terminates
7-17 week the corpus luetum degenerates and the placenta takes over endocrine function
Human Chorionic Gonadotropin (hCG)
- secreted by blastocysts and placenta
- in urine 8-9 days after conception
- stimulates growth of the corpus luteum
Estrogen
increase 30X by end of gestration
- from corpus luteum for first 12 wks then placenta
- causes tissue growth in fetus and mother (mother’s uterus enlarges, mammary ducts, breath growth, widen pelvis)
Progesterone
- from placenta and corpus luteum
- prevents follicular development b/c it stops FSH and LH
- stops uterine contractions
- promotes endometrial cells
- stimulates development of acini in breasts
Childbirth
7th months, the fetus rotates so its head is down
- fetus is a passive player in its own birth
- explusion achieved by contaction of mother’s uterine and abdominal muscles
- fetus chemically by stimulates labor contraction
- sends chemicals when the baby is develop and ready to be born
Define Parturation
the process of giving birth marked by the start of true labour contractions
Factors that Regulate Uterine Contractility
- Progesterone and estradiol balance
- Oxytocin
- Conceptus may produce chemical stimuli promoting its own birth
- Uterine Stretching
