Hormone Physiology

1
(No Transcript)
2
Hormone Physiology

• Nerves vs muscles
• Receptors and target tissues
• Feedback control

3
Hormone Modes of Action
Peptide Hormones
Steroid Hormones
Adrenaline Thyroid Horm. LH, FSH
Estrogen Testosterone Progesterone
4
Vertebrate Endocrine Glands

• Hypothalamus
• Pituitary
• Thyroid/Parathyroid
• Adrenals
• Pancreas
• Ovary, Testis
• Placenta

5
Males
Hypothalamus
Hypothalamus-Pituitary-Gonadal Axis
Testosterone
GnRH
Pitu.
Females
I-
LH
FSH
FSH
LH
Testis
Leidigs
Sertolis
6
Steroid Hormone Metabolism
Cholesterol
Progesterone
Cortesol
Aldosterone
Androstenedione
Testosterone
Estrone
Aromatase
Estradiol
Atrazine stimulates aromatase
7
Hormones and Sexual Development

• Humans
• Ovaries
• All immature eggs present at birth
• Follicle cells estrogen progesterone
• Testes
• Immature sperm produces throughout lifetime
• Leidig cells produce testosterone
• Sertoli cells protect and nurse developing sperm

8
Human Sexual Differentiation
Mullerian duct
5-6 wks sexually indifferent 7-8 wks Gonads
differentiate Males- Genital tubercle
grows Labia close to become scrotum By birth
testes descend
Y chromosome suppresses Mullerian duct
differentiation
9
(No Transcript)
10
Role of Estrogen in Male Fetal Development
Fetal testosterone
DHT masculinizes fetal gonads
Aromatase enzyme
Estrogen masculinizes synapses in fetal brain
11
Variations in Sexual Differentiation
12
Fetal Position and Hormonal Environment

• Male between two females are feminized
• Female between two males are masculinized