Lecture 24: Hormones, Control and Cycles

what is a hormone?

a regulatory substance produced by a gland and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action.

what are the major differences between a hormone and a neurotransmitter?

1. hormones travel through blood, NT through synapses

2. hormones act slow, NT act more quickly

what connects the hypothalamus and pituitary gland?

the pituitary stalk

what is the direct path of the hypothalamus-pituitary?

the hypothalamic supraoptic and paraventricular nuclei produce oxytocin and vasopressin to be transported down pituitary stalk and stored in posterior pituitary gland

what is the indirect path of the hypothalamus-pituitary?

hypothalamus releasing hormones into blood artery, travels to anterior pituitary gland via blood portal system to trigger release of pituitary hormones like prolactin

in the indirect path, what is the hypothalamus' releasing hormone target tissue?

the pituitary gland

what is the master regulator of hormone output?

the hypothalamus

what are all sex hormones derived from?

cholesterol, easily pass through membranes

what are the 3 sex hormone classes ?

androgen, estrogen, progestogen

what is an FSH?

follicle stimulating hormones, goes from pituitary gland to ovaries for egg encased in follicles

what does the FSH determine?

if the egg surrounded by follicles should be released this cycle

when is the lutenizing hormone released from the pituitary gland?

when the hypothalamus receives enough estrogen input from the ovary after FSH stimulation

it goes to the ovary

what is the role of the corpus luteum?

cells that housed the egg, send progesterone to the uterus to signal lining build up and that an egg has been released

what does the uterus release to the corpus luteum in the ovary to signal lining is ready for the egg?

chorionic gonadotropin

what are the two types of ovulation timing?

1. induced (by the act of sex)

2. spontaneous (by season, courtship, gestation period, food, cycle synchrony by odor, etc)

hormones early in development...

organize behavioral systems

hormones later in development...

activate behavioral systems

what are the 1st two things developed in the fetus?

the neural crest for the CNS and the genital bridge

what is the purpose of the genital ridge?

the gametes and genital cells, held off of the developing cell bodies to avoid division and possible mutations

what happens if fertilization occurs?

The corpus Luteum remains functional, the ovulation hormone system halts

what happens if fertilization does not occur?

The corpus luteum degenerates and menstruation begins, chorionic gonadotropin is sent from uterus to ovaries until time is up

what are the 3 reasons exogenous estrogen injected into female pups caused masculinization?

1. if SRY gene is lacking, then it grows up female. default is female

2. aromatization- turns androgen testosterone into estrogen

3. alpha fetoprotein binds to estrogen and take it out of the system to keep the levels of estrogen and testosterone low in females

adding estrogen disrupts or counteracts these processes

What is the direct way the hypothalamus influences the pituitary gland?

Hypothalamic axons release neurotransmitters directly into the blood, which are then detected in the blood by the pituitary gland.

What hormone does a pregnancy test test?

Chorionic gonadotrophin, created by uterus and stops if fertilized

High levels of estrogen lead to male differentiation.

true, in developing males both estrogen and testosterone levels are very high

Which structure releases progesterone in females?

corpus lutem