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MCB 135E Discussion GSI: Jason Lowry Nov 29 – Dec 3.

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Presentation on theme: "MCB 135E Discussion GSI: Jason Lowry Nov 29 – Dec 3."— Presentation transcript:

1 MCB 135E Discussion GSI: Jason Lowry Nov 29 – Dec 3

2 Topics Adolescence and Puberty Functional Changes During Adolescence Male Reproductive System Maturation Female Reproductive System Maturation

3 Adolescence and Puberty Adolescence –Period between onset of reproductive function and adulthood (maturation of functions) Puberty –Maturation of reproductive function –One of many physiologic changes occurring during adolescence

4 Puberty Gonadal Function in Children Characterized by: –Very low levels of sex hormones –Very low levels of GnRH and FSH/LH –Testis and Ovary are differentiated Indicates negative feedback is not functioning correctly

5 Gonadal Function

6 CNS Development and Sexual Maturation CNS Matures progressively from birth to late childhood by: –Dendritic branching and number of synapses –Glial Cell Number –These lead to better communication, better metabolism, more efficient neurotransmissions Due to a decreased threshold, neurons are responsive to lower stimuli levels

7 Role of the Limbic System Cognition Feeding Behavior Conation Sexual Behavior Fear and Rage Motivation

8 Experimental Evidence of Limbic System Immaturity Immature gonads transplanted into an adult animal will mature immediately and demonstrate normal reproductive function The pituitary taken from a prepubertal animal and transplanted into an adult will regulate normal reproductive function Trauma to the hypothalamus will prevent the prepubertal animal from developing normal reproductive function

9 Role of Hypothalamus Gonadostat –Onset of adolescence leads to diminished threshold to sex hormones –This stimulates GnRH neurons which begin the cascade of H-P-G hormones along with negative feedback

10 Functional Changes Adult Reproductive function is established during adolescence –Female – Cyclic –Male – Tonic Puberty Age –Female – 8-13 –Male – 9-14

11 Factors Influencing Onset Hormonal Nervous Somatic Environmental Social Genetic

12 Summary of Charts Peak accelerated growth corresponds with onset of menarche Decreased electrical threshold (developing rats) CNS-Endocrine relationship –Able to see electrical activity that corresponds to ovarian cycle Change in sleep patterns Increased growth during adolescence –Earlier for girls than boys Changes in, B.P., Respiratory volume, heat production, and metabolic rate

13 Male Maturation

14 Maturation Process Maturation of Testes Development of seminiferous tubules Initiation of gametogenesis Secretion of T from leydig cells Maturation of Secondary Sex Organs

15 Maturation of Males: Secondary Organs –Internal Genitalia Seminal Vesicles Prostate –External Genitalia Penis increase in size Scrotum pigmented and rugose Characteristics: –Voice becomes deeper –Hair growth Beard Hairline recedes Pubic hair –Body hair increase –Mental Changes Sex, Aggressiveness –Body changes – muscles, shoulders –Skin - Acne

16 Role of Androgens Major Male Androgen –Testosterone Develop and maintain male secondary sex characteristics Exert important protein, anabolic action, and growth promoting effects To exert inhibitory feedback on Pit LH secretion

17 Testosterone Problems Low T Induces reduction –Hair, bone and muscles, sex drive, sperm count –May result from: Castration, Hormonal Disorders, Diseases Excess T: –Caused by tumors, treatments –Risk of high red cell blood count, prostate gland enlargement, fluid build up, sleep and respiratory problems

18 Female Maturation

19 Ovarian Cycle

20 Ovarian Hormones Estrogen –Stimulates growth and maintenance of secondary sex organs and characteristics –Stimulates ovary and follicle growth –Stimulates growth of smooth muscle and epithelial linings of reproductive tract –Stimulates bone growth and epiphyses closure Protection against osteoporosis Progesterone –Stimulation of uterine gland secretions –Decrease contractility of uterine muscle –Feedback on hypothalamus and pituitary –Some water and electrolyte retention

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