Sex Streoid Hormones Flashcards
Sex steroid hormones
Produced in gonads (testes and ovaries)
Estrogens
The most common is estradiol
Androgens
The most common is testosterone
Progestins
The most common is progesterone
Regulation of All hormone Levels
Neural, hormonal, non-hormonal chemicals
Neural
All endocrine glands all but the anterior pituitary receive neural signals from cerebral or autonomic neuron
Hormonal
Tropic hormones (including anterior pituitary)
Negative feedback
Non-hormonal chemicals
Glucose, Ca2+, Na+
Pulsatile Hormone release
Often with large minute-to-minute fluctuations like ups and downs like a pulse
Cyclic Hormones in human
Male hormone levels are constant
The hypothalamus determine whether hormone levels cycle
Human female hormones go through 28 day cycle
Levels of LH (luteinizing hormone ) and FSH (Follicle stimulating hormone)
LH: active during ovulation and helps control menstrual cycle (release of an egg)
FSH: Helps manage the menstrual cycle and stimulates the ovaries
Levels of LH are high and FSH is low in the anterior pituitary
Cyclic vs. Steady gonadal hormone levels in other species
Animals have breeding seasons
Estrous cycle: increased sexual behaviour
Bright shiny fur to attract other birds and once the cycle ends and the fur’s colour will fade away
Chapter 13.2 Developmental Effects of Sex Hormones
Wednesday’s Lecture
Gonadal Axis
Females: Estrogen and Progesterone negatively feedback to the anterior pituitary and hypothalamus
Effects of Gonadal Hormones
Developmental effects, activational effects
Developmental Effects
Hormone drive the development of males and females from conception to adulthood
Activational Effects
In adults, hormones directly activate behaviour and physiological functions
Hormonal Sexual Development
Humans are dimorphic (the existence of two different forms) (male and female)
All encoded in the sex chromosomes
Male and female have different appearance such as colour and the colour phenotypic forms
Prenatal Developmental Effects of hormones
Genes, Hormones and Brain Development
Genetic sex and gonadal sex
Genetic sex —> Gonadal Sex (gonadal stage is when it’s the period during which indifferent gonads develop into ovaries and testes)
Gonadal Hormones —-> Phenotypic Sex
Gonadal sex is going to release the gonadal hormones
They are not necessarily same things
Sry region of the chromosome
Sry region where Y chromosome is linked to masculinity
It is absence in females, ovaries, lack of testesterone
SRY region and females
It is just not only sry and network that is drives the females characteristics
Not only lacking the SRY
Differentiation of the Primordial (Baslangicta plus an sey) Gonadal Structure
Cortex: potential to be an ovary
Medulla: potential to be a testis
If XY, Sry gene on the the Y chromosome
Sry protein, medulla develops into testis
If XX, no Sry gene
Cortex develops into ovary
Internal reproductive organ development
At six weeks, all fetuses have two complete sets of reproductive ducts
Wolffian system
Capacity to develop into male reproductive ducks (seminal vesicles, vas deferens) Not only promoting the Wolffian system is also inhibiting the mullerian system
Mullerian system
Capacity to develop into female reproductive ducts (uterus, fallopian tubes) Since there is no supplies for the Wolffian system, the mullerian system gets the supply to develop into female system and the testerone part dies of because it doesn’t gets the products that it needs to get
Differentiation of the reproductive system ducts occurs at 3 months of development
Testes secrete testerone and Mullerian-inhibiting substance, and it inhibits the development of the mullerian system
Ovaries release estrogen and progesterone and Wolffian inhibits substance which inhibits the development the Wolffian system
Differentiation of the External Reproductive Organs
Develop for one biopotential precursor
Differentiation occurs in the second moth
-testerone produces male structures
-without testosterone produces male structures
Postnatal Developmental effects of hormones: puberty
Pre- and postnatal hormones “ surges”
Testerone exposure on male humans at the womb for penis
Estrogen exposure in females during puberty and beyond for menstrual cycle
