2005-2006 AP Biology

Human Reproduction & Development

2005-2006AP Biology

Reproductive hormones Testosterone

from testes functions

sperm production Secondary sex

characteristics

Estrogen from ovaries functions

egg production prepare uterus for

fertilized egg Secondary sex

characteristics

LH &FSH

testesor

ovaries

2005-2006AP Biology

Gametogenesis

Occurs in the gonads (ovaries and testes) Meiosis that results in the production of

gametes (haploid cells) from germ cells (diploid cells)

Spermatogenesis and Oogenesis

Slide 2 of 18

2005-2006AP Biology

Spermatogenesis

Occurs in the testes in the seminiferous tubules —results in the production of 4 sperm

Mature in the epididymis and gain mobility

Produced immediately after puberty

Slide 6 of 18

2005-2006AP Biology

SpermatogenesisEpididymis Testis

Coiledseminiferoustubules

Vas deferens

Cross-section ofseminiferous tubule

Spermatozoa

Spermatids(haploid)

2°spermatocytes

(haploid)

1°spermatocyte

(diploid)

Germ cell (diploid)

MEIOSIS II

MEIOSIS I

2005-2006AP Biology

Spermatogenesis

The sperm contains lots of mitochondris (powerhouse of the cell) —why? The sperm have a long journey they

need a lot of energy (hence the need for lots of mitochondria)

2005-2006AP Biology

Sperm production over 100 million produced per day! ~2.5 million released per drop!

Male reproductive system

2005-2006AP Biology

Male reproductive system Testicles

produces sperm and hormones

Scrotum sac that holds testicles outside of body

Epididymis where sperm mature

Vas deferens tubes for sperm to travel from testes to penis

Glands nutrient rich fluid to feed and protect sperm buffer to counteract acids in vagina

2005-2006AP Biology

Male reproductive system

2005-2006AP Biology

Pathway of Semen

epididymis (testes) vas deferens urethra

A vasectomy is a procedure in which the vas deferens is cut so that the man will no longer be able to father children.

2005-2006AP Biology

Female reproductive system

2005-2006AP Biology

Oogenesis

unequal division of cytoplasm

Allows for more nutrition to be available to the egg in case fertilization occurs.

Slide 5 of 18

2005-2006AP Biology

Female reproductive system Ovaries

produces egg and hormones

Uterus Nourishes fetus; lining builds up each month

Fallopian tubes tubes for eggs to travel from ovaries to uterus

Cervix opening to uterus, dilates 10cm (4 inches) for

birthing baby

Vagina Birth canal for birthing baby

2005-2006AP Biology

Female Reproductive System

ovaries – where oogenesis takes place

oviduct (Fallopian Tube) – where fertilization takes place

uterus – where the embryo grows and develops

vagina – birth canalSlide 12 of 18

2005-2006AP Biology

Female reproductive system

2005-2006AP Biology

Female Reproductive Hormones

LH and FSH act on the ovaries and cause them to produce progesterone and estrogen

Slide 13 of 18

2005-2006AP Biology

Female Menstrual Cycle

Each month, a woman’s body prepares for the possible fertilization of an egg

Ovarian cycle = an egg matures and is released

Uterine cycle = the endometrium (lining) of the uterus thickens (becomes ready to have a fertilized egg implant) then breaks down (if no fertilization occurs).

Slide 14 of 18

2005-2006AP Biology

Female Menstrual Cycle

ovulation – release of egg from ovary triggered by a surge of LH.

Slide 15 of 18

2005-2006AP Biology

Female Menstrual Cycle

Day 1 = first day of a woman’s period

Hormonal control is complicated! During different times

of the cycle, estrogen can either stimulate or inhibit other hormones

Slide 17 of 18

2005-2006AP Biology

Female Menstrual Cycle If fertilization occurs, the embryo secretes

HcG which maintains the lining of the uterus hCG is what is tested for in pregnancy

tests

Birth control pills are synthetic progesterone and estrogen that “trick” the body into thinking the woman is pregnant – no ovulation occurs

2005-2006AP Biology

Fertilization

2005-2006AP Biology

Fertilization Joining of sperm & egg

sperm head enters egg

2005-2006AP Biology

Cleavage Repeated mitotic divisions of zygote

1st step to becoming multicellular Unequal divisions establishes body plan

different cells receive different portions of egg cytoplasm & therefore different regulatory signals

2005-2006AP Biology

Cleavage zygote morula blastula

establishes future development

2005-2006AP Biology

Gastrulation Establish 3 cell layers

ectoderm outer layers

skin, nails, teeth, nerves

mesoderm blood, bone & muscle

endoderm inner lining

digestive system

ectoderm

mesoderm

endoderm

2005-2006AP Biology

Placenta Materials exchange across membranes

2005-2006AP Biology

Human fetal development

7 weeks4 weeks

2005-2006AP Biology

Human fetal development10 weeks

2005-2006AP Biology

Human fetal development

12 weeks 20 weeks

2005-2006AP Biology

Human fetal development The fetus just spends much of the 2nd & 3rd

trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid

Week 20

2005-2006AP Biology

Human fetal development 24 weeks (6 months; 2nd trimester)

fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

2005-2006AP Biology

Human fetal development 30 weeks (7.5 months)

umbilical cord

2005-2006AP Biology

Getting crowded in there!! 32 weeks (8 months)

The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming

2005-2006AP Biology

Birth

Hormone induction

positive feedback

2005-2006AP Biology

Intestine

Placenta

Umbilicalcord

Wall ofuterus

VaginaCervix

Birth (36 weeks)

Bladder

2005-2006AP Biology

The end of the journey!