Chapter 4: Human Reproduction
4.1 Male Reproductive System
Misconceptions
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1. Sperm must be released, or else they build
up in the body
2. Sperm die if exposed to air
Misconceptions
•
•
1. Sperm must be released, or else they build
up in the body - sperm do have a limited
lifespan, but, they are broken down and
reabsorbed by body if they stay too long.
2. Sperm die if exposed to air - sperm live
12hours up to several days in female genital
tract. Sperm can live several hours in open air.
Sperm & Egg Size
Male Reproductive System
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Designed for two purposes:
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1) produce sperm
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2) get sperm to egg cells
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Primary S.C.
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Secondary
Sexual
Characteristics
Present at birth
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Secondary S.C.
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Develop at puberty (males start at 11 to 13 and
continue on to 18)
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Begins with brain messaging testes to produce
testosterone
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Include:
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growth spurt - facial, underarm, pubic hair
Sperm Structure
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Head - has haploid nucleus
Middle piece - packed with mitochondria - energy
source
Tail - aka flagellum - propels sperm
Reproductive Structures
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These are the Primary S.C. that mature during
puberty and allow for reproduction.
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Testis
-enclosed in sac (scrotum)
-hot weather & cold weather effect distance from body
-produce + nourish developing sperm
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Seminiferous Tubules
-inside testis
-have cells that undergo meiosis
-these cells become the haploid sperm
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Epididymus
-mature sperm are stored here
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Penis
-organ that enters female during intercourse
-muscular contractions more sperm through male system
until ejaculated with other fluids
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Vas Deferens
-caries sperm to urethra
-urine from bladder cannot travel same time as sperm
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Accessory Glands
-include seminal vesicles, prostate gland, Cowper’s gland
-provide sugar (for energy), protects sperm from acid
environment in female, fluid for swimming
-all this and sperm make what is called semen.
Sperm Production & Development
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Sperm mature in 65-75days.
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Healthy males can produce 200-300 sperm per day
Practice
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Worksheet: 4.1-1 / 4.1-2 (p60-61)
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Label each structure & write function
CYU 4.1 - p111 #3, 6, 7, 12-14
Chapter 4: Human Reproduction
4.2 Female Reproductive System
Misconceptions
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1. When can a woman get pregnant?
Misconceptions
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1. Pregnancy is a rare event, usually possible
during only three days of the menstrual cycle.
Egg is released on day 14 and, if not fertilized,
it will shed the endometrium. During
ovulation, a women’s body temperature
increases.
But, not everyone is the same.
Female Reproductive System
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Designed for two purposes:
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1) produce eggs
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2) nurture a fertilized egg from conception to
birth
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Primary S.C Sexual Characteristics
Secondary
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Present at birth
•
Secondary S.C.
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Develop at puberty (females start at 10-12
years)
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Include:
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growth spurt - underarm, pubic hair development of mammary glands (breasts) widening of hips
Why is egg larger than sperm?
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Must provide nutrients for fertilized egg.
Also has outer barrier that only allows one
sperm to enter.
Egg Production & Development
Female has all her sex cells at birth! Can be born with 2
million but most will break down and leave 400 000 at
puberty. Then, one egg released every month.
Ovaries produce hormones estrogen and progesterone.
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-The female
reproductive
cycle
The Menstrual Cycle
-28 days (can vary from 20 - 40 in some
women)
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-cycle length can vary during lifetime
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-continues until menopause (age 40 - 50)
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-Several eggs develop, only one matures
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-Usually only one ovary releases an egg at one
time (sometimes both do. This can result in
twins)
Path of Egg
-Oviduct (fallopian tubes) > uterus (womb)
-Lining of uterus = endometrium (full of nutrients)
-Cervix is muscular opening between cervix and uterus
-Vagina receives male penis and also the birth canal where the baby
comes out.
-For females, urethra is separate from reproductive system.
Fertilization or Not
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Depending on whether or not an egg is
fertilized, one of two scenarios will happen
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1) Menstruation (no fertilization)
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2) Pregnancy (fertilization)
Menstruation
• Egg is discharged
• since no zygote has implanted on endometrium, it starts to shed
• First Stage - Flow Phase
• menstruation looks like blood is being released
• Second Stage - Follicular Phase
• new follicle develops
• Final Stage - Luteal Phase
• ovulation occurs
• egg travels to uterus
• follicle become corpus luteum (releases hormone called
progesterone - during pregnancy this also prevents other eggs
Pregnancy
•Egg is fertilized if egg is in oviduct and sperm are present
•Two haploid nuclei of sperm and egg fuse together to
create zygote
•Zygote divides quickly into a mass of cells called a
blastula
•After a week, the fertilized mass is called an embryo
•Reaches the embryo and implants into the endometrium
•Baby is born nine months later
Accessory Glands
•Mammary Glands
• During pregnancy, estrogen and progesterone
produced in high levels causing mammary glands
to create milk ducts.
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After birth, progesterone goes down in production
and body starts to create prolactin, a hormone
that causes milk production.
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Each lobe that contains milk is connected with the
nipple.
Try This
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Page 115 #1-4 A-C
Practice
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Worksheet: 4.2-1 / 4.2-2 (p64-65)
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Label each structure & write function
CYU 4.2 - p 116 #12-16