Unit 34 Reproductive System
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Transcript of Unit 34 Reproductive System
34.1 Reproductive Anatomy
KEY CONCEPT Female and male reproductive organs fully develop during puberty.
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
• Estrogen has three main functions. – develop female sexual characteristics – develop eggs – prepare uterus for pregnancy
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
• Testosterone has two main functions.– developing male sexual characteristics – producing sperm
34.1 Reproductive Anatomy
KEY CONCEPT Human reproductive processes depend on cycles of hormones.
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
• 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
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
• 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
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
• Multiple zygotes can result from fertilization.– identical twins from the same egg – fraternal twins from two separate eggs
• Infertility makes reproduction difficult or impossible.
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
• 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
34.1 Reproductive Anatomy
KEY CONCEPT Development progresses in stages from zygote to fetus.
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
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.
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
– 2nd trimester: fetus more active, developed
34.1 Reproductive Anatomy
– 3rd trimester: all organs fully formed
• After about 38 weeks, fetus is ready to be born.
34.1 Reproductive Anatomy
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
34.1 Reproductive Anatomy
• 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