REPRODUCTIVE SYSTEM

1
CHAPTER 43

• REPRODUCTIVE SYSTEM

2
Mammals in General

• Endothermic vertebrates
• Posses mammary glands and hair
• Posses lungs and diaphragm (marine mammals too)
• Hearts are 4 chambered
• Sexual reproduction with internal fertilization

3
Diversity within mammals

• Monotremes egg layers
• ex. platypus
• egg passes through cloaca
• Marsupials pouched mammals
• ex. kangaroo, koala, opossums
• born when very small mature fully in pouch of
  mother
• Placentals most mammals
• ex. dog, cat, horse, human
• complete development in mothers uterus while
  nourishing fetus with a placenta

4
Human Male Reproductive System

• Produces sperm (haploid male gametes) and
  prepares them for delivery to the females body
  so that fertilization can occur.
• Male organs of reproduction testes (2)
• Testes are located outside the body cavity in the
  scrotum to insure that sperm are not harmed by
  normal body temperature.
• Several hundred million sperm are produced each
  day by healthy adult males.

5
Male Reproductive Hormones

• LH (pituitary)- stimulates cells to release
  testosterone
• Testes secrete testosterone - responsible for
  secondary sex characteristics and sperm
  production.
• FSH (pituitary) - stimulates seminiferous tubules
  to produce sperm.

6
Male Reproductive Structures

• Each testicle contains coiled tubes in which
  sperm are produced seminiferous tubules.
• After production, sperm mature as they travel
  through a series of long tubes
• epididymis - sperm mature, develop ability to
  become motile, and are stored here
• vas deferens duct through which sperm travel
  (cutting this vasectomy)
• urethra - passageway out of body

7
Male Reproductive Structures

• Fluids are added during this journey
• seminal vesicles - add fructose to nourish sperm
• prostate gland - secretes an alkaline fluid used
  to combat the acidic environment of the vagina

8
Sperm

• Semen a mixture of these secretions and sperm.
• Sperm is deposited into the reproductive tract of
  the female where they become fully motile.

9
Human Female Reproductive System

• Produces and matures eggs (haploid female
  gametes).
• Houses and nourishes a developing embryo.
• Ovaries (2) - produce eggs (ova)
• located within abdominal cavity
• contain 2M immature eggs at females birth
• usually only one egg matures per month (during
  reproductive years - puberty ? menopause).
• Eggs are formed from follicles inside the ovaries

10
Female Reproductive Hormones

• FSH (pituitary) stimulates an egg to mature
• ? LH (pituitary) causes ovary follicle to release
  egg (ovulation)
• Follicle secretes estrogen which promotes the
  growth of the uterine lining
• After ovulation the follicle changes into the
  corpus luteum which secretes progesterone
• Progesterone and estrogen maintain the uterine
  lining

11
Pregnancy

• If pregnancy occurs - the levels of estrogen and
  progesterone remain high and the endometrium is
  maintained
• If pregnancy does not occur - the corpus luteum
  disintegrates and hormone levels fall
• When this occurs the endometrium is shed
  (menstruation) and a new ovarian cycle begins
• The term menstrual cycle refers to the events
  occurring in the uterus during the month

12
Ovarian/Menstrual Cycles
13
Egg release and fertilization

• When an ovum is released
• cilia sweep egg into fallopian tubes which lead
  from ovaries to uterus where fertilization
  occurs
• uterus is a hollow, muscular organ lined with
  endometrium
• if the egg is fertilized implantation of embryo
  occurs about 6 days later

14
Fertilization and implantation
15
Human Development

• Once the embryo implants, cells from the mothers
  body and the embryos body build the placenta.
• This layer of tissue allows exchange of material
  between their bodies without any actual transfer
  of blood or cells.
• The umbilical cord grows out of the placenta to
  connect the fetus.
• Development progresses through pregnancy until an
  average term of 40 weeks.