Unit 34 Reproductive System

34.1 Reproductive Anatomy

KEY CONCEPT Female and male reproductive organs fully develop during puberty.


The female reproductive system produces ova.

• There are two main functions of the female reproductive system.– produce ova, or egg cells– provide a place where a zygote develops

uterus

cervix

rectum

vaginaurethra

urinary bladder

pubic bone

ovary

fallopiantube


• Estrogen has three main functions. – develop female sexual characteristics – develop eggs – prepare uterus for pregnancy


The male reproductive system produces sperm.

• There are two main functions of the male reproductive system. – produce sperm cells– deliver sperm to the female reproductive system

urinary bladder

vas deferens

pubic bone

prostate gland

penis

urethra

testis

scrotum

epididymisbulbourethralgland

rectum

seminal vesicle


• Testosterone has two main functions.– developing male sexual characteristics – producing sperm


KEY CONCEPT Human reproductive processes depend on cycles of hormones.


Eggs mature and are released according to hormonal cycles.

• Follicle-stimulating hormone (FSH) and lutenizing hormone (LH) regulate egg production. – meiosis produces eggs and

polar bodies– each egg has 23

chromosomes – meiosis is completed at

fertilization

potentialegg

first polarbody

second polarbody

ovum (egg)

Meiosis ICompleted

Meiosis IICompletedonly afterspermenters


• FSH, LH, and estrogen stimulate the release of eggs.– follicle ruptures at ovulation – egg travels into fallopian tube – ruptured follicle becomes corpus luteum

fallopiantube

egg cell

egg released

corpus luteum

uterine wall

ovaryfollicle

uterus

5 to 7 days to uterus


Eggs mature and are released according to hormonal cycles.

• The menstrual cycle has three phases. – flow phase: endometrium sheds – follicular phase: ovulation occurs – luteal phase: corpus luteum forms


• The menstrual cycle stops at menopause. – cycle continues until a woman’s mid-40’s or 50’s– decline in hormone levels make cycles irregular– eventually, cycle stops altogether


Sperm production in the testes is controlled by hormones. • Testosterone, FSH, and LH

stimulate sperm production. – one sex cell divides into

four sperm– each sperm has 23

chromosomes

potentialsperm

4 sperm cells

Meiosis I

Meiosis II


acrosome

head

midpiece

tail

mitochondria

nucleus with 23 chromosomes

• Sperm cells fully mature in the epididymis. – head contains acrosome – midpiece contains ATP – tail allows mobility


Fertilization occurs when a sperm cell joins an egg cell.

• Sperm penetrates an egg. – membrane keeps out other sperm– nucleus of sperm joins with egg – zygote formed


• Multiple zygotes can result from fertilization.– identical twins from the same egg – fraternal twins from two separate eggs

• Infertility makes reproduction difficult or impossible.


Sexually transmitted diseases affect fertility and overall health.

• Sexually transmitted diseases (STDs) are passed from one person to another during sexual contact. – bacterial STDs include chlamydia, syphilis, gonorrhea– viral STDs include hepatitis B, genital herpes, human

papillomavirus, and HIV

HIV


• Viral STDs can be treated, but there is no cure for these diseases.

• STDs attack reproductive organs.– can cause infertility– untreated, some can be

fatal• STDs can be avoided by

abstinence or by using a condom.

A parasite causes trichomoniasis, which can affect fertility.

• Bacterial STDs can be treated, and in many cases, cured with antibiotics


KEY CONCEPT Development progresses in stages from zygote to fetus.


The fertilized egg implants into the uterus and is nourished by the placenta and umbilical cord.

– ectoderm develops into skin and nervous system

• The zygote becomes a blastocyst and implants in the uterus.

– mesoderm develops into Internal tissues and organs – endoderm develops into digestive organs and their

lining

blastocyst

uterine wall

Implantation of blastocyst


placenta

umbilical cord

uterus

amniotic sac

• The blastocyst becomes an embryo. • Embryonic membranes protect and nourish the embryo.

– amniotic sac cushions embryo.

– placenta connects mother and embryo.

– umbilical cord connects embryo to placenta.


A zygote develops into a fully formed fetus in about 38 weeks.

• Human pregnancies are divided into trimesters. – 1st trimester: body plan and early development


– 2nd trimester: fetus more active, developed


– 3rd trimester: all organs fully formed

• After about 38 weeks, fetus is ready to be born.


The mother affects the fetus, and pregnancy affects the mother.

• The fetus depends on the mother for all its nutrition.– mother's diet must support fetal health– mother must avoid toxic chemicals


• The mother’s health is affected by pregnancy in a number of ways. – increase in Calories and body

weight – pregnancy hormones

affecting homeostasis – regular medical checkups

needed

Health & Medicine

Unit 34 Reproductive System