Transcript MCB 135E Discussion

MCB 135E Discussion
GSI: Jason Lowry
Nov 29 – Dec 3
Topics
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Adolescence and Puberty
Functional Changes During Adolescence
Male Reproductive System Maturation
Female Reproductive System Maturation
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
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
Gonadal Function
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
Role of the Limbic System
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Cognition
Feeding Behavior
Conation
Sexual Behavior
Fear and Rage
Motivation
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
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
Functional Changes
• Adult Reproductive function is established
during adolescence
– Female – Cyclic
– Male – Tonic
• Puberty Age
– Female – 8-13
– Male – 9-14
Factors Influencing Onset
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Hormonal
Nervous
Somatic
Environmental
Social
Genetic
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
Male Maturation
Maturation Process
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Maturation of Testes
Development of seminiferous tubules
Initiation of gametogenesis
Secretion of T from leydig cells
Maturation of Secondary Sex Organs
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
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
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
Female Maturation
Ovarian Cycle
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