The Reproductive Systems

1
The Reproductive Systems

• Division of the Species

2
Introduction

• Reproduction is requirement for life.
• Organisms must be able to perpetuate their
  species.
• Humans undergo sexual reproduction.

3
Introduction

• A flagellated sperm from the male fertilizes an
  ovum (egg) from the female.
• A zygote is the end result.
• A zygote is a genetically diverse cell resulting
  from the fusing of ovum and sperm.

4
Functions of Reproductive System

• The functions include
• Gamete Production (ovum and sperm)
• Gamete Transportation
• Gamete Maintenance
• Zygote/Fetus Maintenance
• Production of Sex Hormones

5
Meiosis

• In humans a somatic cell (body cell) is diploid.
• It has 46 chromosomes.
• Human gametes (sex cells) are haploid.
• It has 23 chromosomes.

6
Meiosis

• Meiosis is the type of cell reproduction in which
  a diploid cell is divided and four haploid cells
  result.

7
Meiosis

• Production of sperm is a specialized form of
  meiosis called spermatogenesis.
• Production of an ovum or egg is a specialized
  form of meiosis call oogenesis.
• Only 1 viable ovum is produced (the other three
  are called polar bodies).

8
Meiosis

• Meiosis is divided into Meiosis I and Meiosis II.
• Meiosis I is made up of Prophase I, Metaphase I,
  Anaphase I, Telophase I and Cytokinesis.
• Throughout the process a diploid cell is broken
  down into two haploid cells.

9
Meiosis

• Meiosis II is the second division of meiosis.
• It is divided into the same stages (THEY ARE
  DENOTED BY II).
• The two haploid cells are split into four haploid
  cells.

10
Meiosis
11
Organs of the Male Reproductive System

• The primary organs of the male reproductive
  system are the testes.
• They produce sperm and male sex hormones
  (including but not limited to testosterone).

12
Organs of the Male Reproductive System

• These structures are contained in an external
  compartment called the scrotum.
• Each teste is divided into lobules.

13
Organs of the Male Reproductive System

• Each lobule contains
• Seminiferous tubules, which produce sperm under
  the influence of testosterone.
• Interstitial cells, which produce male sex
  hormones (including testosterone).
  
  
  

14
Organs of the Male Reproductive System

• The seminiferous tubules will unite and give rise
  to the epididymis.
• The epididymis is a coiled tube which transports
  sperm to the vas deference.

15
Organs of the Male Reproductive System

• The seminiferous tubules are lined with an
  epithelial tissue.
• This tissue is made up of
• Spermatogenic cells which give rise to sperm.
• Supporting (nurse) cells which support and
  nourish spermatogenic cells.

16
Spermatogenesis

• Males produce sperm from puberty throughout the
  rest of their life.
• Spermatogonia cells are the diploid (46
  chromosome) cells which produce the haploid (23
  chromosome) sperm.

17
Spermatogenesis

• The sperm is produced in the teste and is
  released in an immature state.
• They then grow to maturity in the epididymis.
• Before this point they are incapable of
  fertilization.

18
Sperm Structure

• A mature sperm consists of
• Head
• Body (Midpiece)
• Tail

19
Sperm Structure

• The head contains the 23 chromosomes.
• It is covered by a helmet like structure called
  an acrosome.
• It contains enzymes which help in breaching the
  wall of the ovum.

20
Sperm Structure

• The body contains many mitochondria.
• They produce ATP which provides energy for the
  long trip to the ovum.

21
Sperm Structure

• The tail is a flagellum.
• It provides locomotion for the sperm.
• Its whip like motion provides the action which
  propels the sperm.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

22
Hormonal Control of the Male Reproductive System

• At puberty, the hypothalamus secretes a
  releasing hormone which targets the male
  pituitary gland.

23
Hormonal Control of the Male Reproductive System

• The anterior pituitary gland secretes two
  hormones
• Follicle stimulating hormone, which stimulates
  spermatogenesis.
• Luteinizing hormone, which stimulates the
  production of male sex hormones.

24
Hormonal Control of the Male Reproductive System

• Male sex hormones are called androgens.
• Testosterone is the major male sex hormone.
• It triggers the growth of hair follicles,
  production of muscle and bone and also vocal
  chords to lengthen.

25
Secondary Male Reproductive Organs

• The vas deference is the muscular tube which
  passes upward from the testis into the abdominal
  cavity.

26
Secondary Male Reproductive Organs

• The vas deference fuses with the ejaculatory duct
  within the prostate gland.
• This is the gland which stimulates ejaculation.

27
Secondary Male Reproductive Organs

• The seminal vesicle is a sac like structure
  attached to the vas deference.
• It secretes a milky fluid which gives nutrition
  to the sperm.
• The fluid also aids in the sperms motility.

28
Secondary Male Reproductive Organs

• The bulbourethral glands are two small structures
  located beneath the prostate.
• They secrete a lubricant for the penis.
• Semen is the fluid which is made up of sperm, the
  fluid produced by the seminal vesicle and the
  lubricant produced by the bulbourethral gland.

29
The Penis

• The penis is the male excitatory organ.
• It is specialized to become erect and deliver
  semen which fertilizes the ovum.

30
The Penis

• The penis goes through four stages to release
  semen
• Erection, spaces within the erectile tissue
  becomes filled with blood during stimulation.
• Emission, movement of semen from the epididymis
  into the urethra
• Ejaculation, forceful movement of semen form the
  urethra to the outside.
• Orgasm, culmination of stimulation which triggers
  the involuntary rhythmic contraction of the
  epididymis (causing emission and ejaculation).

31
Organs of the Female Reproductive System

• The primary organs of the female reproductive
  system are the ovaries.
• They are a solid structure located on the
  posterior wall of the pelvic cavity.

32
Organs of the Female Reproductive System

• The ovary is divided into two parts
• Medulla, made up of CT, blood and lymph vessels
  and nerves.
• Cortex, made up of ovarian follicles which are
  covered with germinal epithelium.

33
Oogenesis

• Oogenesis is very similar to spermatogenesis.
• The primary difference is the fact that only one
  viable egg is produced with each round of
  meiosis.
• The other three structures are called polar
  bodies.

34
Oogenesis

• These polar bodies lack essential organelles such
  as mitochondria.
• The lack of enough organelles within the cell
  cause the occurrence of polar bodies.

35
Ovulation

• During a woman's child bearing years follicle
  stimulating hormone stimulates the maturation of
  one primordial follicle into an ovum.
• A woman is born with the number of primordial
  follicles (and in turn eggs) that she will ever
  have.

36
Ovulation

• Over a 14 day period each month the follicle will
  mature.
• Once it matures Luteinizing hormone will cause
  the follicle to burst releasing a secondary
  oocyte.
• The secondary oocyte is then drawn into the
  fallopian tube.

37
The Fallopian Tubes

• The fallopian tubes are the tubes which connect
  the ovaries to the uterus.
• Fertilization will USUALLY take place here.

38
The Uterus

• The uterus is a muscular organ which receives the
  embryo and sustains its life during development.

39
The Uterus

• The uterine wall is composed of three layers
• Endometrium, inner lining
• Myometrium, middle layer of smooth muscle making
  up bulk of uterus
• Perimetrium, visceral covering

40
The Uterus

• The lower third of the uterus begins to narrow
  forming the cervix.

41
Secondary Female Reproductive Organs

• The vagina is the passageway from the cervix to
  the outside.
• The labia are flaps of skin and fat which serve
  as a protective covering for the vagina and
  cervix.
• The clitoris is the female excitatory organ.

42
Hormonal Control of the Female Reproductive System

• A female is reproductively immature until
  approximately 8 years of age.
• Gonadotropins are the hormones which signal the
  growth and maturation of puberty.

43
Hormonal Control of the Female Reproductive System

• There are two gonadotropins
• Follicle stimulating hormone, secreted from day 0
  to day 14 of menstruation.
• Signals the maturation of primary oocyte.
• Luteinizing hormone, secreted during day 14 thru
  30.
• Causes the release of secondary oocyte into
  fallopian tube.

44
Gestation

• Gestation is the time a zygote, embryo and fetus
  are carried in the female reproductive tract.
• Gestation is complete approximately 266 days from
  fertilization (9 months).

45
Gestation

• Fetal development goes from one cell called a
  blastocyte and will continue until a fully
  functioning human being is developed.
• Cell differentiation is what allows for the
  specialized structures seen in humans.
• Fetal Development