PSB2000 022 Introduction to Brain Behavior Exam 4 Lecture 16 Sex Gender Hormones THE BASICS a Pituitary Gland b Ovaries c Testes d Placenta a PROLACTIN 1 HORMONES chemicals secreted by cells in one part of the body and conveyed by the blood to influence a target cell and coordinate long term changes in multiple parts of the body 2 Hypothalumus secretes RELEASING HORMONES those that promote or inhibit the release of various hormones by pituitary that flow through the blood to the anterior pituitary gland which then releases i Controls secretion of mammary glands ii Increases milk production b SOMATROPIN aka growth hormone i Promotes body growth including that during puberty c GONADOTROPIN controls secretion of the gonads i FOLLICLE STIMULATIN HORMONE increases the production of estrogen and maturation of the ovum in females and sperm in males ii Luteinizing hormone increases the production of progesterone in females testosterone 1 Biological explanation that sexual reproduction increases variation enabling quick evolutionary 2 Corrects errors of disadvantageous mutations in one gene from a mate by replacing it with the normal in males and stimulates ovulation d This is typically a negative feedback system WHY SEX adoptions to changes in the environment copy from the other mate in the offspring 3 Others SEX DERTERMINATION 1 Chromosomes passed down from Mom and Dad a What determines sex b Who determines the sex of the baby PSB2000 022 Introduction to Brain Behavior Exam 4 SEX DERTERMINATION i It s all about the genes 1 But hormones pla an important role in sex too TWO CLASSES OF HORMONES 1 ANDROGENS a Primarily male hormones i Testosterone 2 ESTROGENS 1 Testes produce more androgens than estrogens a Referred to as female hormones because women have higher levels i For example Estradiol a type of estrogen b PROGESTERONE is a type of hormone that prepares the uterus for the implantation of a fertilized ovum and promotes the maintenance of pregnancy GENES AND HORMONES CONTRIBUTE TO DIFFERENCES BETWEEN THE SEXES 1 STEROIDS derived from cholesterol act either on a Protein receptor sites on target cell membrane activating second messenger cascades or b Intrcellular receptor sites that migrate into nucleus and affect gene expression 2 PRODUCED PRIMARILY IN GONADS adrenal cortex can make some a Males Testicles b Females Ovaries 3 MALES FEMALES PRODUCE BOTH CLASSES Androgens Estrogens i Males ii Females Estrogens Androgens CONTROL OF RELEASE OF SEX HORMONES 1 Hypothalumus secretes gonadotropin releasing hormone into anterior pituitary a ANTERIOR PITUITARY RELEASES i LUTEUNIZING HORMONES LH 1 Progesterone Production females 2 Testosterone Production males PSB2000 022 Introduction to Brain Behavior Exam 4 CONTROL OF RELEASE OF SEX HORMONES a Stimulates Ovulation ii Follicle Stimulating Hormone FSH 1 Estradiol Production females 2 Sperm Production males a Maturation of ovum ARE ANDROGENS AND ESTROGENS GOING TO HAVE THE SAME EFFECTS ON SEXES 1 Androgens and estrogens promote the development of typically masculine or feminine features a For example i Estrogens activate the gene for breast growth ii Androgens activate the gene for the growth of facial hair in men 2 Androgens and estrogens influence activity in certain brain areas a Androgens and Estrogens alter patterns of neuron survival during development i Certain brain areas are slightly larger in males or females sexually dimorphic TESTOSTERONE 1 Maturation of male genitalia 2 Promotes sperm production 3 Growth of facial pubic and auxiliary hair in females this occurs from androgen released by the adrenal cortex Increase bone thickness but inhibits bone length 4 Muscular development anabolic steroid 5 6 Enlargement of larynx 7 Associated with sexual arousal in males ESTROGENS 1 Maturation of female genitalia 2 Promotes growth of uterine lining 3 Breast development 4 5 Broadening of hips 6 Associated with sexual arousal in females Increases bone thickness but inhibit bone length PRIMARY SEX CHARACTERISTICS ARE PRESENT AT BIRTH 1 At first a fetus has both MULLERIAN DUCTS oviduct precursors and WOLFFIAN DUCTS vas deferens precursors and undifferentiated gonads ovaries or testes MALE DEVELOPMENT SRY gene on the Y PSB2000 022 Introduction to Brain Behavior Exam 4 S ex determing R egion on the Y causes the primitive gonads to develop into testes 1 2 Developing testes produce ANDROGENS that increase the growth of testes positive feedback 3 Testes also produce Mullerian inhibiting hormone MIH FEMAL DEVELOPMENT 1 Females do not have the SRY gene and their gonads develop into ovaries the egg producing organs 2 Females do not have testes so there is no production of MIH SECONDARY SEX CHARACTERISTIC appear at pubery everything else 1 Facial males only Pubic Auxiliary hair 2 Widended hips Breast development females 3 Muscular development Larnyx enlargement males SEX HORMONES 1 ORGANIZATIONAL EFFECTS Permanent alterations in anatomy physiology and behavior e g primary sex characteristics brain 2 ACTIVATIONAL EFFECTS Triggers reversible alterations in anatomy physiology behavior ORGANIZATION EFFECTS OF TESTOSTERONES sensitive period behavior 1 Sexual differentiation of the external genitalia depends mostly on the level of testosterone during a 2 The human sensitive period for genital formation is about the third and fourth month of pregnancy 3 Female rats exposed to testosterone shortly before or after birth are partly masculinized in anatomy and a Clitoris grows larger than normal b Sexual behavior becomes masculinized 4 Early testosterone promotes the male pattern and inhibits the female pattern ESTROGENS 1 Estradial produces effects on internal genitalia of the female PSB2000 022 Introduction to Brain Behavior Exam 4 2 Extra estradiol does not determine whether the individual looks female or male 3 Estradiol and other estrogens do modify VARIOUS ASPECTS OF THE DEVELOPMENT OF THE BRAIN and the internal sexual organs 4 The absence of sex hormones generally leads to female looking external genitalia 5 If a male rat lacks androgen receptors or is castrated it develops femal like anatomy and behavior SEX DETERMINATION IN MAMMALS IS A PROCESS 1 Male a XY chromosome with Y genes i SRY TDF ii Medulla Testis 1 MRF Mullerian Regression Factor Sertoli cells iii Testosterone Leydig Cells iv Immature male genitalia external sex characteristics 1 5a Dihydro Testosterone v Adult Phenotype 2 Female b XX Chromosome Genetic Gametic Chromosomal Sex vi No SRY vii Cortex
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