Reproduction and Endocrine System Quiz

• Reproduction is the process by which living beings produce copies of themselves.
• In simple organisms, reproduction occurs asexually, whereas in higher organisms (plants and animals), it happens sexually.
• Asexual reproduction involves one individual producing offspring without the need for another.
• Sexual reproduction requires two individuals: a male and a female.

Sexual Reproduction in Animals

• Sexual reproduction involves the fusion of a male reproductive cell with a female reproductive cell to form a zygote.
• Fertilization is the process of fusing two cells.
• The male cell, or male gamete, is called the sperm.
• The female cell, or female gamete, is called the ovum (plural: ova), or egg.

Types of Fertilization

• External fertilization occurs outside the body, as seen in fish and frogs.
• The females discharge eggs into the water, and the males release sperm near the eggs.
• The sperm then swims to fertilize the eggs.
• Internal fertilization occurs inside the female's body, as seen in higher animals, like lizards, crocodiles, birds, and mammals.
• Mammals are animals whose babies are nursed by their mothers; other animals, like birds, crocodiles, snakes, and lizards, lay eggs.
• Platypuses and spiny anteaters/echidnas are exceptional mammals because they lay eggs, though they still nurse their young.

Reproduction in Man

• To understand reproduction in humans, it is important to know about the male and female reproductive systems.

The Male Reproductive System

• Testes (singular: testis) are the male reproductive organs that produce sperm, beginning at puberty
• Puberty is the stage at which a person reaches sexual maturity and can reproduce.
• The testes are in a sac called the scrotal sac, located outside the abdominal cavity.
• The sperm collect and mature in a tube called the epididymis.
• From there, they go through a muscular tube called the vas deferens into the urethra inside the penis.
• As the sperm moves through the vas deferens, secretions from various glands provide fluids.
• The combination of sperm and secretions is called semen.
• Semen is transferred into the vagina (the opening of the female reproductive system) through the penis.
• Sperm have a head and a long tail, which helps them swim to the ovum.

The Female Reproductive System

• The ovaries are female reproductive organs in the lower abdominal cavity, which begin producing ova at puberty.
• Usually, only one of the ovaries produces an ovum each month.
• A muscular tube that ends in a funnel shape with fingerlike projections is located over each ovary.
• An ovum moves through this tube from the ovary to the uterus, or womb.
• This tube is called the Fallopian tube or oviduct.
• The uterus is a muscular organ with a lower portion called the cervix, which connects to the vagina (the opening to the outside).
• The ovaries are connected to the uterus by ligaments.

Fertilization, Pregnancy, and Childbirth

• During intercourse, sperm are introduced into the vagina and travel through the uterus and into the Fallopian tube.
• Fertilization happens when one sperm fuses with the ovum, resulting in the formation of a zygote.
• The zygote repeatedly divides; then, it travels to the uterus, where it attaches to the uterine wall to create the embryo/tiny baby.
• The embryo's cells form tissues that form organs, and slowly, it takes the form of a baby, which is when it is called a fetus.
• The uterine wall has a rich supply of blood vessels that provide the growing embryo with nutrition, and nutrients and oxygen are passed to the embryo through the placenta, which also carries away waste.
• The placenta is connected to the embryo via the umbilical cord.
• The baby (embryo/fetus) grows inside the uterus for about nine months, and this period is called pregnancy.
• The baby is contained and protected within a sac called the amniotic sac, which contains amniotic fluid, which acts as a cushion.
• When the baby is ready to be born, the sac bursts, and the wall of the uterus goes through contractions to expel the baby through the vagina.
• Usually, only one ovum is produced, causing one baby to be born.

Twins

• Sometimes, two ova mature and are released simultaneously, which can result in the birth of fraternal or nonidentical twins if fertilized by two sperm
• Identical twins occur when a fertilized egg divides into two.
• Identical twins look almost like copies of each other and are of the same sex

The Menstrual Cycle

• When a girl reaches puberty, one of the ovaries releases an ovum into the Fallopian tube about every 28 days in a process (ovulation).
• When this happens, the uterus wall thickens with an increased blood supply in preparation to receive and nourish the embryo.
• If the ovum is not fertilized, it is expelled through the vagina along with the lining of the uterus and blood in a process called menstruation.
• Ovulation, thickening of the uterine wall, and menstruation make up the menstrual cycle, which usually lasts about 28 days.

Secondary Sexual Characters

• Adolescence (referred to puberty) is associated with many physical and emotional changes in boys and girls around the age when they attain puberty.
• Girls generally reach puberty between 11 and 14 years, while boys reach puberty between 13 and 16 years.
• Puberty is characterized by the onset of menstruation in girls and sperm production in boys, and it is associated with physical changes known as secondary sexual characters.
• Secondary sexual characters: enlargement of the breasts, widening of the pelvic girdle, and growth of hair in the pubic region and armpits in girls
• Deepening of the voice, growth of hair on the face, pubic region, and armpits, enlargement of the penis and scrotum, and increase in muscle mass in boys

The Endocrine System

• This body system consists of several scattered glands called endocrine glands, which separate from the others.
• The chemicals produced by the endocrine glands are called hormones (chemical messengers).
• Hormones act like chemical messengers and are transported by the blood to specific organs or tissues to perform particular functions, therefore controlling and coordinating the functioning of many organs of the body.
• The testes make the male sex hormone called testosterone.
• This hormone leads to the development of secondary sexual characteristics in males.
• The ovaries make estrogen, which promotes secondary sexual characteristics in females.
• Estrogen also prepares the uterus for pregnancy
• The ovaries also release progesterone, which causes changes in the body during pregnancy.

Table 4.1 The Endocrine Glands with Location and Function

• Pituitary gland
  • Location: Base of the brain
  • Function: Regulates growth and the functioning of the other endocrine glands
• Thyroid
  • Location: Near the larynx
  • Function: Controls many activities of the body including the rate at which energy is produced
• Parathyroids (4 glands)
  • Location: Behind the thyroid
  • Function: Control the balance of calcium in the body
• Adrenals (2 glands)
  • Location: Attached to each kidney
  • Function: Regulate heartbeat, respiration rate and blood pressure
• Pancreas
  • Location: Below the stomach
  • Function: Controls glucose level in blood
• Testes
  • Location: Outside abdominal cavity
  • Function: Promote development of secondary sexual characters
• Ovaries
  • Location: Lower part of abdominal cavity
  • Function: Control secondary sexual characters and changes related to pregnancy

Gender and Sex

• Sex is determined by biological characteristics, whereas gender is a social or cultural concept.

Gender Roles

• Gender differences are a social or cultural concept that varies between societies and over time.
• Gender roles are functions that society considers feminine or masculine and are taught to children from a very early age.
• The idea of the roles men and women should perform is often reflected in their choice of profession.
• Women are often associated with nurturing, caring, and looking after the old and the young, and men are often associated with protection, valour, physical stamina, and the ability to put up with physical hardships.

Taboos

• A taboo is a social or religious custom that prohibits or restricts a certain behavior or practice.
• For example, widow remarriage was considered taboo in India until the Widow Remarriage Act was passed in 1856, even after that act was frowned upon.
• The determination of the sex of a fetus by testing the amniotic fluid, the mother's urine or ultrasonography is prohibited by law due to female foeticide.
• Female foeticide is a part of life in many parts of India, so the female-to-male ratio in the country has fallen; normally, the number of females should be the same as or greater than the number of males.

Test your knowledge of the human reproductive and endocrine systems. Questions cover topics such as gamete fusion, hormone functions, and reproductive organs. Evaluate your understanding with this comprehensive quiz.