733 Reproductive System

puberty

the period during which the body transitions from childhood to sexual maturity. This process is marked by complex interactions between the brain, endocrine system, and reproductive organs, resulting in significant physical, hormonal, and psychological changes

puberty hypothalamic axis

the hypothalamus and pituitary become less sensitive to negative feedback and secrete more gonadotropin-releasing hormone (GnRH), follicle stimulating hormone, and luteinizing hormone leading to increased sex steroid production and the emergence of secondary sex characteristics

hormonal regulation during puberty in females

estrogen is responsible for the development of secondary sexual characteristics and the maturation of the reproductive organs

hormonal regulation during puberty in males

testosterone drives the development of male secondary sexual characteristics and stimulates spermatogenesis

physical changes in females during puberty

• breast development

• menarche

• growth spurt

• body hair

• changes in body composition → fat deposits in the breasts, hips, and thighs

physical changes in males during puberty

• testicular enlargement

• penile growth

• pubic hair development

• voice deepening

• muscle mass and growth spurt

• facial and body hair

puberty effects on bone

• GH and IGF-1 drive longitudinal growth at the growth plates

• estrogen increases bone miner accrual, the close the growth plates

• much of adult bone mass is deposited around peak height velocity

puberty effects on muscle

• testosterone increases muscle cross sectional area

• males: neuromuscular spurt in strength and power

• females: increase body mass not consistently matched by increased strength

puberty effects on tendons and ligaments

• bone growth outpaces lengthening of the muscle-tendon unit

• estrogen: greater ligamentous laxity, wider pelvis, larger Q angle

puberty impacts on movement

• peak height velocity

  • (F) 11-13 years

  • (M) 13-15 years

• female ACL injury rates rise after puberty: landing mechanics, dynamic knee valgus

menstrual cycle

involves coordinated interactions between the brain and ovaries, affecting tissues in the uterus, fallopian tubes, vagina, and breasts

menstruation and follicular phase days

days 1-5

menstruation and follicular phase details

• endometrial lining from the previous cycle is shed

• follicle development is stimulated by FSH

• A dominant follicle matures into a primary oocyte

follicular and proliferative phase days

days 6-13

follicular and proliferative phase details

• the endometrium begins to proliferate (grow) in response to estrogen

• estrogen climbing and reaching peak around day 12-13

• LH surges around day 13

ovulation phase days

day 14

ovulation phase details

• LH hormone surge triggers egg to be released from ovary

  • once egg is released, LH decreases

luteal secretory phase days

days 15-28

luteal secretory phase details

• egg becomes corpus luteum

• estrogen rises but stays relatively low

• LH and FSH low

• progesterone increases

• endometrium thickens with rise of progesterone

reproductive years impact on bone

• estrogen acts directly on bone

• female athlete triad→ low bone mineral density, stress fractures, long term osteoporosis risk

reproductive years impact on muscle

• estrogens act directly on muscle

• triad→ impaired recovery, decreased performance

reproductive years impact on tendons and ligaments

• higher rate of ligamentous injury right before or around ovulation, when estrogen peaks

• hypothesized: estrogen related increased laxity

reproductive years impact on movement

• triad irregular/absent menses, fatigue, recurrent injuries

• dysmenorrhea: midline pelvic pain radiating to lumbar back or posterior thighs

• PMS/Premenstrual dysphoric disorder

dysmenorrhea

pain during menstrual cycle or menstrual cramps. It typically occurs just before the onset of menses and lasts for the first 1-2 days of menstruation; very prevalent and can affect up to 90% of individuals

premenstrual syndrome

physical and mental manifestations that occur during the luteal phase and disappear within the first few days of menses

premenstrual dysphoric disorder

when PMS symptoms are severe enough to impact ADLs; common in about 3% of women

female athlete triad

combination of low energy availability, menstrual dysfunction, and low bone mineral density in physically active females

female athlete triad causes

inadequate caloric intake relative to training demands leading to decreased GnRH, reduced estrogen, and impaired bone formation

female athlete triad clinical signs

irregular/absent menses, fatigue, recurrent injuries, stress fractures, decreased performance

female athlete triad impact on movement system

increased risk for stress fractures, impaired recovery, long term risk of osteoporosis and infertility

menopause

a normal physiologic event that marks the end of the reproductive years and is characterized by the cessation of menstrual cycles and accompanying hormonal changes

perimenopause

the time from when menstrual cycles become irregular until 1 year after the last normal menstrual period

what follows perimenopuase

menopause- cessation of menstrual bleeding for a continuous 12 month period from perimenopause

midlife and beyond impacts on bone

• menopause decreases estrogen and decreases bone mass which increases osteoporosis risk

• males: decrease bone mineral density; much of testosterone effect is via conversion to estradiol

midlife and beyond impacts on muscle

• menopause decreases muscle mass

• males: testosterone decreases ~1%/yr from the 3^rd decade which leads to a decrease in muscle mass, strength, and increase in fat mass

midlife and beyond impacts on tendons and ligaments

• estrogens act on periarticular tissues

• Arthralgia affects up to 50-60% of women

midlife and beyond impacts on movement

• vasomotor symptoms, sleep disturbance, depressive symptoms, subjective cognitive decline

• fatigue (males)

• decrease in muscle and bone mass with decreased estrogen

• resistance training helps minimize musculoskeletal changes

physiology of menopause

• number of ovarian follicles decrease which causes a decrease in estrogen produced by ovaries

• anterior pituitary increases secretion of FSH and LH

• progesterone decreases causing a build up of endometrium

vasomotor symptoms of menopause

hot flashes and night sweats; these occur in 80% of women and can significantly affect quality of life, leading to irritability, difficulty concentrating, and poor sleep

pregnancy changes in the cardiovascular system

a 30-50% increase in blood volume and 20-30% increase in cardiac output to nourish the growing fetus

pregnancy changes in the respiratory system

increase in tidal volume and a decrease in respiratory reserve, leading to a higher oxygen consumption rate

pregnancy changes in the musculoskeletal system

there is a shift in the center of gravity due to growing uterus, relaxin increase in joint laxity leading to low back and pelvic girdle pain

pregnancy changes in the endocrine system

facilitates pregnancy through a surge of hormones like hCG, progesterone, and estrogen which support the fetus’ growth and development

placenta

a transient organ developed during pregnancy, plays a crucial role in hormone production and nutrient exchange between mother and fetus

pregnancy and postpartum impacts on bone

• center of gravity shifts with growing fetus

• postural changes contribute to low back pain

pregnancy and postpartum impacts on muscle

• pelvic floor muscles stretch extensively during labor and may be weakened

• diastasis recti→ weakened core

pregnancy and postpartum impacts on tendons and ligaments

• Relaxin increases joint laxity and loosens pelvic ligaments

• pelvic girdle can persist post-partum

pregnancy and postpartum impacts on movement

• low back pain, pelvic girdle pain, carpel tunnel syndrome

• pregnancy: increases blood volume (30-50%) and heart rate

• postpartum: increases risk of blood clots

uterus anatomical changes post partum

involution- where it contracts to return to its pre-pregnancy size and position

breasts anatomical changes post partum

undergo changes to facilitate lactation, becoming larger and potentially engorged as milk production begins

diastasis recti post partum

a condition where the abdominal muscles separate, leading to a wekened core and potential back pain

back pain post partum

due to changes in posture and the physical demands of caring for a newborn

pelvic girdle pain post partum

this pain arises from the relaxation of liagments and joints during pregnancy, which can persist post partum

carpel tunnel syndrome post partum

some mothers develop this condition due to fluid retention and repetitive movements such as lifting the baby

pelvic floor post partum

these muscles which may have stretched and/or weakened during pregnancy and childbirth begin to recover. Recovery can be supported through pelvic floor exercises

hormonal fluctuaitons post partum

marked by significant hormonal shifts, including a rapid decrease in pregnancy hormones such as progesterone and estrogen. These fluctuations can affect mood and well being

cardiovascular adjustments post partum

the CV system undergoes adjustments as the increased blood volume during pregnancy gradually decreases. it is a time where the body is at a higher risk for blood clots

metabolic changes post partum

there are changes as the body shifts from the pregnant to non pregnant state including adjustments in fluid, electrolytes, and mineral balances

human chorionic gonadotropin hormone (hCG)

supports corpus luteum, used in pregnancy tests

progesterone

thickens uterine lining, prevents contractions, supports placenta and breast development

estrogen group

regulates uterine growth, supports fetal development, prepares for lactation

estradiol (E2)

dominant form, supports uterine, breast tissue growth, decreases after childbirth

Estrone (E1)

weaker form, present throughout life, smaller role in pregnancy

estriol (E3)

most abundant during pregnancy, promotes uterine and fetal development, rises significantly in later stages

prolactin

essential for milk production, levels rise during pregnancy and post partum

relaxin

loosens ligaments, softens cervix, relaxes smooth muscles

oxytocin

stimulates uterine contractions and milk ejection

spermatogenesis

sperm production occurs in the seminiferous tubules of the testes and begins at puberty. Takes 64-72 days for immature sperm cells to develop in mature spermatozoa

spermatogonia

divide and undergo meiosis to form haploid spermatids which mature into fully developed sperm

sperm structure

• head: contains genetic material & can penetrate egg

• mid piece: mitochondria for energy

• tail: propulsion

testosterone

essential for stimulating sperm production and maturation

FSH in males

from pituitary gland, promotes sperm development by acting on cells in the seminiferous tubules

LH in males

stimulates Leydig cells in the testes to produce testosterone, which is crucial for spermatogenesis and maintaining male reproductive function

where is sperm stored

in epididymis, gaining motility and fertilizing capacity and are stored there until ejaculation

ejaculation

sperm travels through the vas deferens, mix with fluids from accessory glands to form semen, and are expelled through the urethra during ejaculation

inhibin

secreted by sertoli cells, provides negative feedback to the anterior pituitary to regulate FSH

Dihydrotestosterone (DHT)

a more potent derivative of testosterone, critical for prostate growth, external genitalia development, and secondary sex characteristics such as facial hair

estradiol in males

produced in small amounts via peripheral conversion of testosterone, plays roles in bone health, cognition, and feedback regulation of the hypothalamic-pituitary-gonadal axis

andropause of late onset hypogonadism

testosterone levels gradually decline ~1%/year beginning in the third decade of life

what could andropause of late onset hypogonadism lead to

decreased libido, erectile dysfunction, reduced muscle and bone mass, increased fat mass, fatigue, and mood or cognitive changes

age related decline in testosterone

contributes to loss of muscle mass and strength, decreased bone mineral density, increased fat mass, and fatigue

low energy availability in male athletes

inadequate energy relative to training demands supresses the hypothalamic pituitary gonadal axis. Consequences include reduced testosterone, decreased BMD, stress fracture, fatigue, and impaired performance and recovery

exogenous testosterone and anabolic steroid-androgenic steroid use

exogenous suppress endogenous testosterone production through negative feedback. Gains in muscle may outpace adaptation to tendon. Other risks include testicular atrophy, impaired spermatogenesis, and cardiovascular risk