Lecture 9 - The Reproductive System Flashcards
(18 cards)
Outline the cycle of the human reproductive system
Pregnancy/ conception
Birth
Menarche (first period)
Menstruation
Pregnancy
Menopause
Why are humans so reproductively successful?
Biological adaptations - bipedal, thumbs for tool use, large brain size, life stages (childhood) - enhanced mobility, problem solving
Prolonged childhood - Extended learning and brain development - survival and cultural skills
Delayed reproduction - After physical maturity - improved offspring survival
Post- reproductive life - Grandmother hypothesis (caregiving), transfer of knowledge - increased child survival, social cohesion
How do we become male or female?
5 or 6 weeks after conception then sexual differentiation
Due to a cascade of hormonal changes
Gonads become testicles or ovaries
Testosterone supports forming of male ducts
Uterus and fallopian tubes dissolve
Oestrogen supports formation of female ducts
Male ducts shrink
What are the main structures that are common in males and females?
Gonads (testes/ovaries)
Gametes ( sperm/eggs)
Ducts
External genitalia
Urethra
Outline the male reproductive system
Testes surrounded by the scrotum
Penis
Urethra
Bulbourethral gland
Ejaculatory duct
Prostate gland
Seminal vesicle
Outline spermatogenesis
Mitosis of spermatogonium
Forms a primary spermatocyte
DNA replication - tetrad formation
Meiosis 1 - Secondary spermatocytes
Meiosis 2 - Spermatids
Spermiogenesis - maturation - Spermatozoa
Regulated by testosterone and FSH
64-72 days
Outline the hormonal regulation of male reproductive function
Hypothalamus to the reproductive structure
LH - testosterone - effects CNS, bone and muscle growth, secondary sex characteristics, glands and organs - inhibits hypothalamus
Outline the female reproductive system
Ovaries - all eggs are created before the woman is born
Uterus - perimetrium, myometrium, endometrium
Fallopian tubes
Regulated by oestrogen, FSH, LH, progesterone
Outline the structure of an ovary
Cortex
Medulla
Oocyte
Corpus luteum
Corona radiata
Outline the ovarian cycle
Roughly 25 - 34 days
Follicular phase
Menstrual phase from 1 - 5 - first day of menstruation - start counting 14 days for ovulation
Endometrium shed - new ovarian follicle beginning cycle
Proliferative phase - release of another egg
Luteal phase - Secretory phase - more stable, higher body temp - thickening of endometrial wall
Body temp lowest when ovulating day 14
Hormonal regulation of the female reproductive cycle
Follicular phase - follicle development - oestrogen mostly
Ovulation - highest oestrogen, slight increase in inhibin and progesterone
Luteal phase - Lower oestrogen, progesterone increases, inhibin increases
Outline the hormone regulation of ovarian activity
Estrogen - stimulates CNS, bone and muscle growth, female secondary sex characteristics, glands and organs, endometrial growth
Similar to test in males but higher bf and lower muscle - effects are different
Estrogen - stimulates LH, increases pulse frequency
Outline the 40 week developmental stage
0-4 - Germinal stage - fertilisation
5-6 - Gonadal ridge formation
7-8 - Differentiation begins
9-12 - Ovarian development
13-16 - External genitalia differentiation
17-20 - Rapid ovarian development (peak oocyte number)
21-28 - Regression of Oogonia - Oogonia and oocytes undergo atresia - reduce numbers
29-36 - Maturation and final positioning
37-40 - Preparation for birth
Outline the development of structures within human development
CNS and heart first
Teratogens - actions from the environment
CNS from 3 to 20 weeks - most likely to be effected at this time
Heart - problems until 6 weeks
Outline the intergenerational influences hypothesis
Maternal health and epigenetic programming influence offspring fertility
Suboptimal conditions cascade across generations
Grandmother’s and mother’s environments affect offspring reproductive health
Outline the graph showing size attained as age increases
Best for a child to have a solid general growth
Quick brain development 95 % of adult size by 8
Immune system peaks at 12 - to prevent infection
Outline the difference in male and female growth velocity
Highest in early years
Girls have a peak velocity height earlier than boys
Pelvic canal reaches adult size at 18
Boys then have a peak velocity height around 2 years after - larger growth spurt
Outline the sex spectrum
Typical male - XY
Subtle variations like low sperm count
Moderate variations - anatomical variation in genitalia
46, XY DSD - womb and fallopian tubes plus males genitalia
Ovotesticular DSD - XX , XY - ovarian and testicular tissue
46 XX testicular DSD - XX - small testes, male genitalia
Moderate variations - premature ovarian shutdown
Subtle - Excess male sex hormones
Typical female - XX female genitalia
