VPHY TEST 3

The ability to conceive children

Fertility

Is defined clinically as not being able to achieve pregnancy after 1 year of having regular, unprotected intercourse, or after 6 months if the women is older than 35 years of age

Infertility

Many different medical conditions and other factors can contribute to fertility problems, and an individual case may have a single cause, several causes, or in some cases __ identifiable cause

No

What are three ways you might assess or measure fertility?

Sperm count

Regularity of menstrual cycle

Possibility for implantation in uterus and maintenance of pregnancy over course of gestation

What factors affect a person’s fertility?

Sex chromosomes

Genes

Hormones

Humans have __ pairs of chromosomes: __ pairs of autosomes and __ pair of sex chromosomes.

23

22

1

X and Y chromosomes determine ___. Each egg produced by a female (XX) has an X chromosome. Sperm produced by a male (XY) have either an X chromosome or a Y chromosome

Sex

Biological sex is NOT ______

Gender

assigned at birth (male, female, intersex)

Sex

How one identifies in society (man, woman, non-binary, etc.)

Gender

Y-chromosome contains the ___ region, for sex-determining region of the Y chromosome, which encodes a transcription factor, partially directs the formation of the typical male sex organs

SRY

sex-determining region of the Y chromosome, which encodes a transcription factor, partially directs the formation of the typical male sex organs

SRY gene

Female internal and external structures; impaired ovarian development

Absent or limited pubertal development

Infertility; hormone therapy can promote female characteristics

Has XO sex chromosome pair

Turner Syndrome

Male internal and external structures

Hormone treatment can promote male characteristics

Low testosterone; small testes; infertility; reduced facial hair; weak muscles; breasts may develop

Has XXY chromosome pair

Klinefelter syndrome

Hypothalamic-Pituitary Gonadal Axis:

Hypothalamus —releases ____ —> Anterior Pituitary —releases ___ & ___ —> Gonads —release ___ & ___ —> effector tissues

GnRH

LH & FSH

Androgens & Estrogens

The releasing hormone released from the hypothalamus that stimulates LH and FSH production from the anterior pituitary

GnRH

Luteinizing Hormone (tropic hormone) released from anterior pituitary

LH

Follicle-stimulating hormone (tropic hormone) released from the anterior pituitary

FSH

Androgens and Estrogens released from the gonads ______ production of GnRH from the hypothalamus and ______ production of LH&FSH from the anterior pituitary

Decrease

Decrease

________ include testosterone, (T), and DHT

Androgens

________ include estrone and estradiol (E2)

Estrogens

__________ is a precursor for all steroid hormones

Cholesterol

________ converts androgens into estrogens

Aromatase

The enzyme ___________ converts testosterone to DHT

5-alpha-reductase

Estrogens and androgens have an action, wherever there is a ______

Receptor

Variation in Fertility Across Life Span:

• Infertile (incapable of conceiving children)

• Gonadotropin levels are LOWEST

  FSH > LH

Childhood (pre-pubescent, 0-7 yrs)

Variation in Fertility Across Life Span:

• Becoming physiologically capable of conceiving children (initial menses/growth of testes)

• Initiated by onset of pulsatile GnRH

• Gonadotropin levels increase

  LH > FSH

Puberty (~8-14)

Variation in Fertility Across Life Span:

• Fertility fluctuates with menstrual cycle, stays relatively high for sperm-producing individuals

• Gonadotropin levels continue to increase

  LH > FSH

Adult (“reproductive years”) 18-44 yrs

Variation in Fertility Across Life Span:

• Menstruation becomes more sporadic/less frequent

• Decreases/changes in libido

• Decrease in estrogen levels → hormone replacement therapy ovarian source of estrogen

Climacterium (45-55 yrs)

Variation in Fertility Across Life Span:

• Cessation of menstrual cycle

• Decrease in sperm count/mobility

• Gonadotropin levels are highest

  FSH > LH

Senescence (56+ yrs)

The Effect of Stress on Axis of Reproduction:

Cortisol ______ HPG axis

Chronic stress can cause:

• _________ (absence of menstruation)

• ___ libido

• Erectile _________

Inhibits

Amenorrhea

Low

Dysfunction

What are the four phases of human sexual arousal?

1) excitement

2) plateau

3) orgasm

4) resolution

Four phases of human sexual arousal:

1) Excitement

• increased blood flow to the ________ (vasocongestion)

• vaginal _________ and _________ of labia

• Testes ____ and scrotum ______

Genitals

Lubrication

Swelling

Swell

Tightens

Four phases of human sexual arousal:

2) Plateau

• ________ excitement continues to grow

Sexual

Four phases of human sexual arousal:

3) Orgasm

• ________ short phase of sexual response

• Sensation of orgasms across ___ don’t not differ

• Some females can go between _______ and ______ many times

Climactic

Sexes

Plateau

Orgasm

Four phases of human sexual arousal:

4) Resolution

• body slowly returns to its original ________ state

• __________ period occurs during male resolution phase (and some females) in which individuals cannot become aroused for a period of time

unexcited

Refractory

When does spermatogenesis begin in males?

At puberty

Spermatogenesis:

Two meiotic divisions of one ____________ yield 4 __________ (round) which then develop into 4 mature _______ (elongated)

Spermatogonium

Spermatids

Sperm

Spermatogenesis:

________ process, gradual decline with age

Continuous

Spermatogenesis:

• Total time to produce ejaculated sperm varies from __-__ days

42-76

Spermatogenesis:

• sperm concentration typically >__ million/mL of ejaculate (less than 15 million/mL → infertility - W.H.O.)

20

Spermatogenesis:

• Daily sperm production of ___ to ___ million spermatozoa

  → Lots of sperm storage

150

275