Human Reproduction Reproductive System - PowerPoint Presentation

Slide1

Human Reproduction

Slide2

Reproductive System

The function of the reproduction system is to

make new members

of the species.

Individual

can

lead a healthy life without reproducing BUT…

Reproduction is single most important system for

continuation

of a species

(without it no species could produce another generation)

Slide3

Puberty

Puberty is period of

rapid growth and sexual maturation

Reproductive system becomes fully

functional

At end of puberty, male and female reproductive organs are fully developed

Varies in age from 9-15 (females usually 1 year earlier than males)

Slide4

Puberty

Begins when

hypothalamus

signals

pituitary

gland to produce increased levels of two hormones that affect gonads

*follicle stimulating hormone

(FSH)

*luteinizing hormone

(LH)

Slide5

Male Reproductive System

Main function is to produce and deliver

sperm

Release of FSH and LH stimulates cells in testes to produce

testosterone

Testosterone stimulates the development of

sperm

Once large numbers of sperm are produced in testes



puberty is complete

= functional reproductive system

Slide6

Slide7

Structures of Male Reproductive System

Scrotum

-an external sac which holds the testes

Temp is 1-3 degrees cooler than normal body temperature (lower temp is important for proper sperm development)

Seminiferous tubules-

one

of hundreds of tiny tubules in the testes in which sperm is produced

Slide8

Gametes

A

Gamete

is a cell which is used during sexual reproduction

Gametes are usually either

sperm or egg cells

.

Gametes have

HALF

the number of chromosomes as normal cells.

When gametes are created, they don’t undergo mitosis, they undergo…

MEISOSIS!

Slide9

Meiosis

Meiosis

is the process of cell division where an normal cell ends up as four cells with half the original number of chromosomes.

If a cell has

4

chromosomes to start with, at the end of meiosis, its four daughter cells would have

2

chromosomes.

Slide10

Meiosis vs. Mitosis

Slide11

Structures of Male Reproductive System

Sperm cell

Consists of:

Head

(highly condensed nucleus)

Midpiece

(packed with energy releasing mitochondria)

Tail

aka flagellum (propels cell forward)

At tip of head is small cap that contains enzyme vital to fertilization

Slide12

Structures of Male Reproductive System

Epididymis

-structure in which sperm fully mature and are stored

Vas deferens

-

tube from the epididymis

Extends upward from scrotum into abdominal cavity

Urethra

- merges with the vas deferens

Tube that leads to the outside of the body thru the penis

Slide13

Structures of Male Reproductive System

Seminal fluid

-

nutrient rich fluid which nourishes the sperm and protects them from the acidity of the female reproductive tract

Semen

- combination of sperm and seminal fluid

Between 50-130 million sperm present in 1mL of semen

(about 2.5 million sperm per drop)

Slide14

Male Reproductive System

Ejaculation

- sperm are ejected from penis by smooth muscle contractions

Regulated by

autonomic nervous system

= not completely voluntary

About

2-6mL

of semen released

Slide15

Female Reproductive System

Primary organs are

ovaries

(located in abdominal cavity)

Puberty starts when

hypothalamus

signals

pituitary

gland to release FSH and LH

FSH stimulates cells within ovaries to produce

estrogen

Slide16

Female Reproductive System

Main function of female reproductive system is to produce

ova or egg cells

Also prepares female’s body to nourish developing embryo

Ovaries only produce one mature ovum (egg)

each month

Slide17

Egg Development

Follicle

is cluster of cells surrounding single egg

About 400,000 primary follicles in each ovary

Function of follicle is to

help the egg mature

for release into reproductive tract where it can be fertilized

Every 28 days follicle gets larger and completes first meiotic cell division

Slide18

Egg Development

When meiosis is complete, single large haploid egg and 3 smaller cells called polar bodies are produced (very little cytoplasm and soon disintegrate)

Slide19

Egg Release

Slide20

Egg Release

Ovulation

is process in which egg is released from ovary

Fallopian tubes

are fluid filled tubes connected to ovary, egg moves thru by push of microscopic cilia

Egg can be fertilized at this point

After a few days, egg passes into

uterus

Lining of uterus is ready to receive fertilized egg (if fertilization occurred)

Slide21

Slide22

Structures of Female Reproductive System

Cervix

is outer end of uterus

Vagina

is canal beyond the cervix that leads to the outside of the body

Slide23

Menstrual Cycle

Begins at puberty and continues until mid 40’s

Permanent stopping of

menstrual cycle

called

menopause

(50’s)

During menstrual cycle, egg develops and is released from ovary and uterus is prepared to receive fertilized egg

If egg is

not fertilized

, then egg is discharged along with the lining of the uterus

Slide24

Phases of the Menstrual Cycle

Follicular

phase

Ovulation

Corpus luteum

phase

Menstruation

Slide25

Phases of Menstrual Cycle

Follicular phase

10-14 days

FSH

from pituitary stimulates maturation of

egg in follicle

Estrogen

from follicle stimulates thickening of uterine lining

Slide26

Phases of Menstrual Cycle

Ovulation

mature egg released from follicle

FSH

production inhibited by

estrogen

, which stimulates release of

LH

by pituitary

Slide27

Phases of Menstrual Cycle

Corpus Luteum

phase

10-12 days

burst follicle develops into

corpus luteum

, which produces progesterone

progesterone

stimulates further thickening of

uterine lining

Slide28

Phases of Menstrual Cycle

Menstruation

If egg is not fertilized, progesterone secretion

decreases

Uterine lining degenerates

Tissue and blood are

discharged

from body

Slide29

Slide30

Sexually Transmitted Diseases

Spread by

sexual contact

Serious

health

problem in US

Most commonly reported STD is

chlamydia

(more than 3 million cases/year)

Bacteria

Females

15-19

show highest incidence of infection

Puts them at risk for infertility due to damage caused to reproductive system

Slide31

STD’s

Other bacterial STD’s include

syphilis

(can be fatal) and

gonorrhea

Viruses include hepatitis B, genital herpes, genital warts, HIV

Can be prevented by abstinence from sexual contact

(100% effective!!!)

Next safest option is to use a condom

(every time!!!!!)