1.2 Reproductive System

AZIZAH, S.PD REPRODUCTIVE SYSTEM

REPRODUCTION

REPRODUCTION is…

Function of REPRODUCTION is

Ensures that each species continues to live on although individual organisms may die

Need for the vital for the survival of all species

REPRODUCTION

There are two types of reproduction

Sexual, which is need male and female sex cells and happened in multicellular organisms and produces offspring that are genetically different from their parents.

Asexual, happen through the cell division in unicellular organisms and produces offspring genetically identical to their parent

The first step of sexual reproduction is fertilization , when the male sex cells (sperm) meets female sex cells (ovum/egg)

MALE REPRODUCTIVE SYSTEM

MALE REPRODUCTIVE ORGANS

Testis  male gonads which produce sperm

Epidydimis

Scrotum

Sperm duct

Urethra

Penis

Male sex glands

MATURATION OF MALES

Puberty in males happen about two years later that females (ages 10 to 15)

Puberty begins with a change of hormone levels

At puberty the hypothalamus releases increased amounts of gonadotropin-releasing hormone (GnRH), resulting in increased levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) or interstitial cell-stimulating hormone (ICSH) in males, ICSH stimulates the testes to produce testosterone, the primary sex hormone in males.

Control of LH/ICSH and FSH production in males

testis

Seminiferous tubules:

Contain receptor proteins for FSH in Sertoli cells.

FSH stimulates spermatogenesis to occur.

Leydig cells:

LH stimulates secretion of testosterone.

Contain receptor proteins for LH.

SPERMATOGENESIS

Spermatogonia:

Replicate initially by mitosis.

One of the 2 primary spermatocytes undergoes meiosis:

2 nuclear divisions:

1 st meiotic division produces 2 secondary spermatocytes.

2 nd meiotic division produces 4 spermatids.

FEMALE REPRODUCTIVE ORGANS

FEMALE REPRODUCTIVE SYSTEM

Ovary  female gonads which produce ova/eggs

Egg/ova

Oviduct

Uterus

Cervix

Vagina

MATURATION OF FEMALES

Puberty in females happen at 8 to 13 years of age

Puberty begins with a change of hormone levels

At puberty the hypothalamus releases increased amounts of gonadotropin-releasing hormone (GnRH), resulting in increased levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH). Increased levels of FSH stimulate the development of follicles, saclike structures that produce oocytes in the ovary, and the increased luteinizing hormone stimulates the ovary to produce larger quantities of estrogens. The increasing supply of estrogen is responsible for the secondary sexual characteristics.

CONTROL OF FSH AND LH IN FEMALES

OVARY

In the ovary, the egg begins development inside a sac of cells known as a follicle .

Each month, one of these follicles develops and releases its product.

This release through the wall of the ovary is known as ovulation.

OOGENESIS

OOGENESIS (CONTINUED)

In females, meiosis begins before birth, but the

oogenesis process is not completed. When birth, woman have a primary oocytes

Primary oocytes begin to undergo meiosis in the normal manner at puberty and it will form a secondary oocytes

Secondary oocytes will completes 2 nd meiotic division as fertilization occurs.

If fertilization doesn’t occur, the oocytes cell will release out of the body through menstruation

MENSTRUAL CYCLE

MENSTRUAL CYCLE (CONTINUED)

1 st - 7 th day : secretion of FSH and LH, uterine lining is broken down and shed.

Both FSH and LH stimulate the maturation of a single follicle (follicle increase in size) in one of the ovaries

The follicle secretes increased amounts of estrogen that cause the lining of the uterus to increase in thickness.

14 th day: ovulation occur, the remains of the follicle is converted into a corpus luteum by the action of LH.

Corpus luteum produce both estrogen and progesterone.

Estrogen and progesterone stimulate the development of the endometrium and preparation of the uterine inner lining for implantation of a zygote.

If pregnancy does not occur, the corpus luteum degenerates, resulting in a reduction in the amount of progesterone needed to maintain the

lining of the uterus, and the lining is shed.

MENSTRUAL CYCLE (CONTINUED) FSH and LH released Uterine lining (endometrium) is shed, maturation of follicle Follicle secretes estrogen Lining of the uterus increase in thickness ovulation LH change remain of the follicle into a corpus luteum Corpus luteum produce estrogen and progesteron Uterine lining (endometrium) increase in thickness Fertilization doenst occur, corpus luteumdegenerates, progesteron reducted

FERTILIZATION

As fertilization occurs, secondary oocyte completes 2 nd meiotic division.

Sperm enters ovum cytoplasm.

Ovum nuclear membrane disappears, zygote formed.

.

FERTILIZATION (CONTINUED)

Cleavage:

30-36 hrs. after fertilization, the zygote divides by mitosis.

50-60 hours after fertilization, it develops into morula.

Blastocyst develops:

Inner cell mass

Fetus.

Surrounding chorion:

Trophoblasts form placenta.

FERTILIZATION (CONTINUED)

FUNCTION OF PLACENTA

Site for exchange of gases and other molecules between maternal and fetal blood.

Gas exchange:

0 2 and C0 2 .

Nutrient exchange.

Waste exchange.

Synthesis of proteins and enzymes.

AMNION

Envelop the embryo and umbilical cord.

Amniotic fluid initially is isotonic, but as fetus develops; concentration changes by urine and sloughed cells of the fetus, placenta, and amniotic sac.