Endocrine System

Big Idea: How does the body use chemical signals to maintain homeostasis?

Describe how this person feels walking on the bridge.List situations in your life that cause stress.

Describe how your body reacts to this stress.

Nervous vs Endocrine

• If you wanted to send information to ONE person, what would you do?

• If you wanted to send information to MANY people, what would you do?

Nervous vs Endocrine

• The nervous system sends messages quickly and directly via neurons

• The endocrine system is the slow message system that delivers messages to every cell of the body by releasing chemicals called hormones.

HypothalamusThe hypothalamus makes hormones that control the pituitary gland. In addition, it makes hormones that are stored in the pituitary gland.

Pituitary glandThe pituitary gland produces hormones that regulate many of the other endocrine glands.

Parathyroid glandsThese four glands release parathyroid hormone, which regulate the level of calcium in the blood.

ThymusDuring childhood, the thymus releases thymosin, which stimulates Tcell development.

Adrenal glandsThe adrenal glands release epinephrine and nonepinephrine, which help the body deal with stress.

Pineal glandThe pineal gland releases melatonin, which is involved in rhythmic activities, such as daily sleep-wake cycles.

ThyroidThe thyroid produces thyroxine, which regulates metabolism.

PancreasThe pancreas produces insulin and glucagon, which regulate the level of glucose in the blood.

OvaryThe ovaries produce estrogen and progesterone. Estrogen is required for the development of secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg.

Testis The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics

Section 39-1 The Endocrine Glands

regulates

Concept MapSection 39-2

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

GrowthWater

balanceReproduction Metabolism

Calciumand glucose

levels

Responseto stress

The Endocrine System

Pituitary

Ovaries

Testes Thyroid Pancreas Adrenals

Parathyroids

Beta cells release insulin into the blood

Body cells absorb glucose

Blood glucose level decreases

Homeostasis: Normal blood glucose level

Blood glucose level decreases

Alpha cells release glucagon into blood

Liver converts glycogen to glucose

Blood glucose level increases

Blood glucose level increases

Liver converts glucose to glycogen

Actions of Insulin and GlucagonSection 39-2

Reproductive System

The function of the human reproductive system is to produce, store, nourish and release sex cells (gametes – eggs and sperm).

In addition, the function of the female reproductive system is to nourish a developing embryo.

The fusion of egg and sperm produces a zygote.

What would happen if you removed a person’s circulatory system?

What would happen if you removed a person’s reproductive system?

Why is the reproductive system important if a person can survive without it?

Does every member of a species have to reproduce?

Large intestine

Rectum

Seminal vesicle

Prostate gland

Bulbourethral gland

Epididymis Testis

Scrotum

Penis

Urethra

Vas deferens

Pubic bone

Urinary bladder

The Male Reproductive SystemSection 39-3

Fallopian tube

Ovary

Urinary bladder

Pubic bone

Urethra

Vagina

Uterus

Cervix

Rectum Vagina

Fallopian tube

Ovary

The Female Reproductive SystemSection 39-3

Female reproductive system

Contrary to males, who are able to produce about 1000 sperm per minute, females produce one egg per month.

All the eggs a woman will ever have are formed while she is in her mother’s uterus (about 5 million eggs) by the time she is a five month old fetus.

Only about 400 eggs will be ovulated.

Your period starts a cycle that usually produces a single egg that can be fertilized.

Cycle lengths are from 21 – 35 days, but usually are 28 days.

FSH and LH reach the ovaries and signal them to produce estrogen. Estrogen causes the egg to ripen.

The egg ripens in a sac called the follicle. When an egg is ripe, it is released from the follicle into the abdomen where it is picked up by the fimbria of the Fallopian tube.

Ovulation, which takes about 2 minutes to complete, usually occurs 14 days AFTER the onset of the period in a 28 day cycle.

Ovulation always occurs 14 days BEFORE the onset of the period (bleeding).

Therefore, if you have a 35 day cycle, you will ovulate on day 21 and if you have a 20 day cycle, you will ovulate on day 6.

What happens next?

After the egg is in the Fallopian tube, it continues to ripen and prepare itself for the sperm.

The egg is capable of being fertilized for 24 hours.

Sperm can live in the vagina, cervix, uterus and Fallopian tubes for 3 - 5 days.

During sexual intercourse a small amount of seminal fluid containing millions of sperm cells is expelled through the man’s penis and deposited below the woman’s uterus. Helped by the movements of the woman’s vagina and uterus, some of the sperm cells manage to swim through the cervix to the uterus. Many get no further and either die of exhaustion or the warmth of the uterus. Only the strongest sperm pass through the uterus to the Fallopian tubes. And only half of these enter the correct tube where an egg may be waiting. Eventually a few hundred sperm approach the egg. An egg is fertilized when one sperm enters it.

How the gametes meet

If fertilization occurs…

Fertilization occurs in the Fallopian tube.

One sperm penetrates the egg’s protective outer layer. Once this happens, a chemical reaction occurs that makes it impossible for any other sperm to penetrate the egg.

The fertilized egg becomes a dividing ball of cells which implants into the uterine wall.

Implantation of blastocyst

Day 7 Fertilization

Day 4

Day 3 Day 2

Day 1

Day 0

Egg released by ovary

Fertilization and Implantation

Uterine wall

Blastocyst

Morula

4 cells 2 cells Zygote

Ovary

Fallopian tube

Embryo development

Male and female embryos are identical for the first 6 weeks.

After the 7th week of development, the embryo’s reproductive organs produce sex hormones that make it either male or female. The male testes produces androgens and the female ovaries produce estrogens.

What triggers a female to become female is not so much the presence of estrogen as the absence of testosterone. Without testosterone, both male and female embryos would develop as female.

The mother produces so much estrogen that diffuses across the placenta, that the amount the embryo produces is insignificant.

The testosterone produced by the male embryo is the essential difference between males and females. Male and female reproductive organs develop from the same embryonic tissue.

Testicular feminization syndrome – Y chromosome present, but externally female due to either lack of testosterone production, or problem with testosterone receptor cells.

Female androgenital syndrome – Genetic female with male characteristics (enlarged clitoris).

6 week old embryo

7 week embryo

12 weeks 20 weeks Full term

12 weeks

Fetus

After 8 weeks of development, the embryo is called a fetus.

On average it takes 9 months (40 weeks after the last menstrual period) for a fetus to become full term. Babies born before 8 months (37 weeks after the last menstrual period) are premature.

Fetuses older than 23 weeks can be viable

20 weeks

28 weeks 36 weeks

40 weeks – Full term

http://www.childbirthconnection.org/article.asp?ClickedLink=343&ck=10236&area=27

After birth, the testes and ovaries continue to produce hormones that influence the development of reproductive organs.

Testes and ovaries produce gametes after puberty (starts between ages 9 – 15).

Secondary sexual characteristics in females: development of breasts, widening of hips and an increase in body fat.

Secondary sexual characteristics in males:

deepening of the voice, broadening of the chest and shoulders

and development of facial and body hair

If fertilization does not occur…The egg dies and the lining of the uterus is shed,

resulting in a period (menstruation/bleeding)

Mythical Methods of Birth ControlOR, THE ONES THAT DON’T WORK

• Withdrawal (a small amount of semen can escape from the penis before ejaculation, plus you have to trust that he will pay attention and “pull out”)

• Rhythm (counting days and only having sex when it is “safe” – you really need to have a regular cycle and know your body)

• Intercourse during menstruation (if you have a short or erratic cycle you can be ovulating during your period)

• The First Time (yes, virgins CAN get pregnant)

• Standing up immediately after sex• Douching with Pepsi or Coke• Praying