Transcript Chapter 31/32/33

The Reproductive
System and
Development
Ch. 31,32,33
Organs of the male reproductive
• Introduction
• Testes
– Structure
– Spermatogenesis
Formation of sperm
Spermatogenesis
Male internal accessory organs
• Epididymus
– Coiled tube near testis
• Vas deferens
– Muscular tube that empties into urethra.
• Seminal vesicle
– Secretes fructose to nourish sperms
– Prostaglandin to cause female reproductive system
tubes to contract to help convey sperm to egg
• Prostate gland
– Located at base of bladder
– Alkaline fluid
• Bulbourethral glands
– mucus
• Semen
Male external reproductive
organs
• Scrotum
– Holds testes away from body
• Penis
– Conveys sperm into the female body
Hormonal control of male
reproductive function
• Hypothalamic and pituitary
hormones
– Hypothalamus - Gonadotropin
releasing hormone
– Anterior pituitary –
• Luteinizing hormone
• Follicle stimulating hormone
Organs of the female
reproductive system
•
•
The organs produce /maintain egg
cells, transport site of fertilization ,
and provide favorable environment
for embryo
Ovaries – primary gonads
•
Primordial follicles – prenatal
•
Oogenesis – oocytes begin
meiosis, process halts and
resumes at puberty
Follicle maturation – at puberty,
FSH – follicle maturation
Ovulation
•
•
– Structure – solid, ovoid, lateral pelvic
cavity
– Medulla – connective tissue and
blood vessels, nerves.
– Cortex - follicles
– Millions
– Primary oocyte and follicular cells
– 400-500 will be relased throughout a
woman’s life.
– If not fertilized, it will degerate.
Female internal accessory
organs
• Uterine tubes – oviducts
– Suspended by ligament
– Lead to uterus
• Infundibulum – expanded
section of uterine tube
– Fimbrae – on margins
• Uterus – houses developing
embryo
• Vagina – muscular tube
– From uterus to outside
– Path through which sperm
and baby travel during birth
Female external reproductive
organs
• Labia majora – enclose and protect
other reproductive organs
• Labia minora-vascular
• Clitoris – anterior end of vulva
• Vestibule – glands secrete mucus
Hormonal control of female
reproductive function
• Female sex hormones
– From hypothalamus
– Gonadotropic releasing hormone
(secreted around 10 years of age)
– Anterior pituitary hormones
• FSH – stimulates ovaries to secrete
estrogen (Secondary sex characteristics –
breast development, increased adipose
tissue)and progesterone (triggers uterine
changes during menstrual cycle.)
• LH – triggers ovulation
Hormones and the menstrual
cycle
Female reproductive cycle
• Monthly changes in uterine lining – menstrual
flow – shedding of the lining
• Fsh – starts menstrual cycle
• Lh – mid cycle surge in LH triggers ovulation
• More estrogen/progesterone secreted
• If pregnancy does not occur, uterine lining is
shed
• Menopause – when cycles cease – middle
age
• Cause – aging of the ovaries when follicles no
longer mature
Mammary glands
• Accessory organs within the breast Produce and secrete milk
• Location: Anterior thorax
• Infants nurse to cause the milk to let
down into the ducts of the breast.
Birth Control
• Vasectomy/tubal ligation –
considered permanent (can be
reversed)
Other birth control
• Mechanical barrier
– Condom, diaphragm, cervical cap
• Chemical barrier
– Spermicides
– More effective with mechanical barrier
• Oral contraceptives (birth control pills)
– Contain estrogen
• Injectable contraception- intramuscular injection of
Depo-Provera – suppress release of oocyte for 3
months.
• Contraceptive implants – progesterone containing
capsules or rods inserted under skin – may work for
5 years
• Intrauterine devices – IUD. Solid object inserted into
uterus – interferes with implantation.
Pregnancy
• Presence of developing offspring in uterus
– result of fertilization
• Transport of Sex Cells
– Upper one third of uterine tubes
– Thin uterine secretions
• Fertilization
– Sperm erode corona radiata and zona
pellucida - one sperm cell penetrates egg
membrane
– Changes in egg membrane prevent additional
sperm from entering
– Result in a diploid zygote
Prenatal Period
• Early Embryonic
Development
– Undergo series of mitotic
divisions called Cleavage
– Dividing mass of cells Morula
– Blastocyst when
implanted
– Embryo – first 8 weeks of
development
– Fetus – after 8 weeks
Hormonal changes during
pregnancy
• Human chorionic gonadotropin
secreted during blastocyst stage
– Maintains corpus luteum and uterine
lining
• Aldosterone
– Promotes fluid retention
• Parathyroid hormone
– Maintains high calcium level
Embryonic Stage of Development
• Weeks 2-8
• Placenta
development
• Internal organ
development
• Facial feature
development
Week 2
• Embryonic disk development
– Germ layers
• Ectoderm - nervous system and sensory organs,
epidermis, linings of mouth and anal canal
• Mesoderm - muscle, bone, marrow, blood, lymphatic
vessels, reproductive organs, kidneys, linings of
cavities
• Endoderm - linings of digestive and respiratory tract,
urinary bladder and urethra
– Yolk sac development - blood cell formation
and stem cells
– Week 3 - allontois forms - forms blood cells
and becomes umbilical arteries and veins
Week 4
•
•
•
•
Heart beating
Head and jaw
Limb buds
Gas and nutrient
exchange through
placenta
Week 8
• Amnion develops - amniotic
fluid
• Umbilical cord
• Embryo is 30 millimeters in
length and all systems are
formed
Fetal Stage of development
• 8th week
• Rapid Growth and change in
proportions
• Bones begin to ossify
• 5th month - mother feels
movement - lanugo and
sebum cover skin
• Final trimester - brain cells
and organs mature
• 40 weeks - parturition - birth
Birth process
Postnatal Period
• Changes in mother:
– Production and secretion of
milk
• Prolactin no longer inhibited
after birth
• First milk – colostrum
– Watery fluid rich in proteins and
antibodies
• Milk let down triggered by
oxytocin
• Human milk is the best
possible food for babies
– Hormonal changes –
depression (post-partum)
Neonatal period of development
Changes in infant
• Birth - 4 weeks
– First breath – must be forceful to inflate lungs for
first time
– Surfactant in full term newborn reduces surface
tension
• Live off fat for 2-3 days
– Susceptible to dehydration – homeostatic
mechanism of kidneys not yet fully functioning
• Changes in fetal circulation
– Umbilical vessels constrict, several holes close,
between heart and liver bypass.
– Occur during first fifteen minutes after birth, but it
may take longer for foramen ovale to close
between right and left parts of the heart. (foramen
ovale bypassed lungs during prenatal
development.)