Hormones

Endocrine/hormonal system is made up of __________________

many glands, distributed throughout the body

Hormone

chemical messenger secreted by a gland

Hormones VS neurotransmitters

• hormones travel through the bloodstream to its target

• neurotransmitters go across a synapse

Hormones act _______ (fast/slow), while neurotransmitters act more __________(fast/slow)

slow

fast

Hypothalamus is located on the ________ side of the brain.

ventral

hypothalamus is connected to the ________ gland. it controls the regulation of ______ ____________.

pituitary

sex hormones

Pituitary gland can control things through both _______ and ________ mechanisms.

direct

indirect

Direct mechanism

• Hypothalamus has cell bodies that go into their axons and extend into the pituitary gland.

• Neurons can deposit neurotransmitters directly into blood.

Indirect Mechanism

• Hypothalamus can look at hormone levels and can adjust by releasing its own hormones

• then goes into blood and pituitary gland can analyze blood content to decide what hormones to release

The hypothalamus is the master regulator for the ___________ system.

endocrine

All hormones are derived from ________.

cholesterol

3 hormones (classes of molecules) that come from cholesterol

1. Androgens - ex: testoterone

2. Estrogens - ex: estradiol

3. Progestogens - ex: progesterone

Describe the pathway for female hormones in detail.

1. Hypothalamus

• recognizes a signal and release GNRH into the blood to its target tissue (Pituitary Gland)

2. Pituitary Gland

• receives GNRH signal

• release FSH (follicle stimulating hormones) which stimulates follicles and decides which of the follicles (humans its 1-2) will be released in this cycle

• FSH circulates to the target tissue, Ovary

3. Ovary

• secretes its own hormone, estrogen into bloodstream

• estrogen goes back to hypothalamus

4. Hypothalamus

• send a signal to pituitary gland to tell it to release LH (lutenizing hormone)

• LH acts on the ovary.

5. Ovary

• ovulation occurs when the egg released from follicle and travels down reproductive tract (fallopian tubes)

• remanants of follicle become corpus luteum (in ovary) which releases Progesterone.

• this goes to the uterus

6. Uterus

• makes lining thick in prep for egg

• secrets chrionic gonadotropin hormone to keep corpus luteum alive

If this fails, then what happens (uterus does not secrete chorionic gonadotropin)?

Corpus luteum disappears → uterus goes back to normal → start cycle again

what if it works?

hCG present → corpus luteum survives → progesterone stays high → uterine lining maintained → pregnancy continues

What regulates the cycle (2)

1. induced ovulation (only a few animals do it) - act of sex is what causes these animals to ovulate

2. spontaneous ovulators - seasonal cues → social and odor cues (such as birds who birth babies when its warm)

Birth control pills have _______________ in order to _____

estrogen and progesterone

mess with both these systems

Formation of hormone system either goes to …. or …

gametes (eggs and sperm)

genital ridge

Genital Ridge

bump to make sure cells dont divide and to eliminate the chance of mutation

Every organism starts out with a blueprint for _________ duct and _______ duct.

wolffian duct

mullerian duct

what gene is on the Y chromosome that causes the testes to devlop

SRY gene

Testes will produce _________ →androgens

steroid hormones

Females have a _____ number of _____ gametes.

Males have a _______ number of _______ gametes (small/large)

small, large

large, small

when a female is born she has _________ eggs. as you get older (30) you have ____% of eggs left

300,000

12%

Older sperm may lead to ….

because…..

more mutations

more cell divisons lead to a higher chance of errors

Describe the mouse social preference hormone experiment

A test animal (adult mouse) is placed in the center compartment.

On one side is a stimulus female (often “receptive” or hormonally primed so she signals mating availability).

On the other side is a stimulus male (often sexually experienced to make him socially/sexually relevant).

The animal can move freely between sides.

They then measure:

Time spent near the female vs. male

How often it approaches each

General interaction (sniffing, proximity)

results:

1. XY males + testosterone early

Grow up showing typical male-typed behavior

Spend more time near the female

→ “masculinized” behavior (as expected)

2. XY males + estrogen early

Still behave like males as adults

Still prefer the female

→ estrogen early in male pups does not feminize behavior

3. XX females + testosterone early

As adults, behave like males

Prefer the female

→ early testosterone masculinizes female behavior

4. XX females + estrogen early

Also show male-typical behavior

Prefer the female

→ surprisingly, estrogen early in development does not feminize behavior and may actually disrupt normal female pathway organization

3 reasons why these females given estrogen act like males when they grow up

1. default state is female

2. testosterone is metabolized into estrogen in developing embryo → aromatization

3. compound called a-fetoprotein that binds up estrogen and take it out of system

• females have no SRY gene and low levels of testosterone and estrogen

• males make testosterone and is aromatized into estrogen

• not enough a-fetoprotein to bind up all estrogen

Androgen insensitivity

• genetic defect → androgen receptors

• cant respond to it

• female developed to male

DES - diethylstilbestrol

drug given to pregnant women for cramps or other things

• synthetic estrogen hormone

• can be problem to female babies - issue with cycling

Congenital adrenal hypertrophy (CAH)

• disorder involving the adrenal glands

• “hypertrophy” → glands overactive and not functioning properly

Normal hormone pathway

hypothalamus → pituitary → adrenal glands

adrenal glands produce…..

this sends …… feedback.

hormones

negative

What goes wrong in CAH?

• feedback loop is broken

• hypothalamus and pituitary think that theres not enough hormone, so they increase signaling

• adrenal glands overproduce hormones, esp androgens

effects of excess androgens

show masculinization effects

may have reproductive issues