3- Human reproductive system

The main reason for reproduction is survival in order to avoid the extinction of organisms

If the reproductive system is one of the useless body systems, why do we need reproduction?

Human reproductive system

a set of organs and structures that work together to ensure the survival of the species

1. To produce gametes

2. To store and transport reproductive cells

3. To nurture offspring as it develops

4. To produce hormones

Functions of the reproductive system

Epididymis

where male gametes are stored

Uterine tubes/fallopian tubes/ oviduct

where female gametes are stored

female reproductive system

nurtures the development of a new individual

testes

site of sperm production

spermatogenesis

production of sperm

vas deferens

carries sperm from the testes to the urethra during ejaculation

ejaculation

discharge of semen from the penis through the urethra.

seminal vesicle

gives atleast 60% of the total fluids of semen to provide nourishment

prostate gland

gives 20% of the total fluids of the semen for the survival of the sperm on its journey through the cervix

basic fluids

what type of fluids does the prostate give in order to survive the acidic environment of the vagina

urethra

double doorway; acts as a passage way for both urine and semen when exiting the body

1. Testes

2. Epididymis

3. Vas deferens

4. Seminal vesicle

5. Prostate

6. Urethra

pathway of sperm from production to its exit

penis

hollow cavities in males that can be filled with blood

• physical

• visual

• plus hormones

stimulants required to achieve erection

androgens; testosterone

these _____ , specifically _, aids in the processing of physical and visual cues

physical stimulation

type of stimulation that leads to erections faster

erections are required in order to allow penetration needed for fertilization by ejaculation in the female body

why do penises need erections?

stress

reduces testosterone production

circumcised penises are easier to clean; uncircumcised penises are aroused better due to the foreskin stimulating the penis

the differences between circumcised and uncircumsised penises

sperm moves with the help of semen but it is especially moved with the help of muscle contractions caused by physical stimulation

how is it possible for the sperm cells to travel from the epididymis to the seminal vesicle?

ovary

produces egg and female sex hormones

fimbriae

structure that acts like a net to collect the egg after it is released from the ovary

uterine tubes/ fallopian tubes/ oviducts

passageway for eggs from the ovaries to the uterus

uterine tubes/ fallopian tubes/ oviducts

site of fertilization by the sperm

uterus

where a fertilized egg implants and grows into a fetus during pregnancy

implantation

when a fertilized egg (blastocyst) attaches to and embeds into the uterine lining,

endometrium

the inner lining of the uterus that sheds and become menstruation if fertilization does not occur

cervix

allows menstrual blood to flow from the uterus

cervix

serves as a pathway for sperm to enter the uterus

vagina

receives the penis during sexual reproduction

vagina

allows menstrual blood to exit the body

vagina

wherethe baby passes through during childbirth

the movement of the egg is caused by cilia-like structure of the fallopian tube which propels the egg to move from one place to another

how is it possible for the egg to transport from the ovary to the uterus if the egg itself is not motile?

ectopic pregnancy

occurs when a fertilized egg implants outside the uterus, most commonly in the fallopian tube

the egg cell, which nourishes the zygote, expires quickly. fertilization must occur as early as possible while the egg is at its ripe stage

why does fertilization occur in the fallopian tube?

1

how many egg cells are USUALLY produced in 1 cycle?

multiple births

rare case of more than one egg produced during ovulation, resulting in twins, triplets, quadruplets, and the like

chemoattractants

specialized signaling molecules secreted by the eggs to guide the sperm toward them

estrogen

causes contractions of the vagina during intercourse

1. ovary

2. fimbriae

3. fallopian tube

4. uterus

5. cervix

6. vagina

pathway of the egg from production to its exit

1. testes

2. epididymis

3. vas deferens

4. urethra

5. ejaculation

6. vagina

7. cervix

8. uterus

9. oviducts

10. fertilization

journey of the sperm cell for fertilization

menstrual cycle

natural recurring process in the female reproductive system, lasting about 28 days on average

menstrual cycle

prepares the body for potential pregnancy

28 days

how long does a menstrual cycle last usually

follicular phase

when the pituitary gland releases hormones that stimulate growth and development of ovarian follicles

follicle stimulating hormone (FSh)

hormone high during the follicular phase and triggers the gonads to produce eggs

pituitary glands

triggers the gonads to produce androgens necessary to produce the secondary sex characteristics

ovulation phase

when a mature egg is released from the ovary and is ready for potential fertilization

luteal phase

empty ovarian follicle becomes the corpus luteum, producing hormones that prepare the uterus for possible embryo implantation

luteinizing hormone (LH)

hormone high during luteal phase that structures and prepares the corpus letum

corpus luteum

a temporary, yellow endocrine structure in the ovary that develops from a ruptured follicle after ovulation

corpus luteum

Its primary function is to secrete progesterone (and some estrogen) to support pregnancy by preparing the endometrium, or to regress if fertilization does not occur, starting the menstrual cycle

luteal phase

usually when abdominal cramps happen

calendar method

natural for of family planning by tracking the menstrual cycle to predict ovulation

gametes

specialized reproductive cells that carry half the genetic material required to form a new organism

1. haploid cells

2. produced through meiosis

3. two types in humans (sperm in males; egg cells/ovum in females)

characteristic of gametes

1. they contain only one set of chromosomes to ensure that when they fuse during fertilization, the resulting zygote has the correct diploid number

2. this process ensures a stable chromosome number across generations and enables genetic diversity through sexual reproduction

why are gametes haploid

1. head

2. neck

3. body

3 main parts of the sperm

head

front part of the sperm

nucleus

contains the genetic material of the male parent

acrosome

cap-like structure that covers the front half of the nucleus

acrosome

contains hydrolytic enzymes that digest the cell’s outer layer to facilitate fertilization

nuclear vacuoles

small pockets that may influence DNA packaging

cell membrane

outer covering that protects and maintains cell integrity

post-acrosomal sheath

assists in binding with the egg

redundant nuclear envelope

remains of nuclear covering; support structure

neck

short connecting region between the head and the middle piece

centrioles

organize the microtubule structure of the tal

centrioles

provide rigidity and structure to the neck to avoid damage

centrioles

initiates tail formation and contributes to embryo development

body

energy production center of the sperm

mitochondria

these organelles wrap around the axoneme to form the mitochondrial sheath within the middle piece, producing ATP to fuel tail movement

axoneme

structural core that drives movement

terminal disc (annulus)

dense ring structure located at the junction of the middle piece and the principal part of the tail

terminal disc (annulus)

prevents the mitochondria from sliding down the flagellum and provides structural stability

transverse

manner in which sperm moves

plasma membrane

continuous lipid bilayer that encloses the entire sperm cell

plasma membrane

protects the internal components

plasma membrane

regulates ion exchange essential for motility

plasma membrane

houses the specific surface receptors needed to bind with the egg during fertilization

axial filament

properls the sperm forward with whip-like motion

end piece

tapering tips aids smooth movement

nucleus

where genetic information is stored in the egg cell

cytoplasm

jelly-like substance that gives support for the nucleus to stay at the center

1. outer exoplasm or egg cortex

2. inner endoplasm or ooplasm.

cytoplasm is divided into:

corona radiata

outermost later surrounding the egg cell and consist of follicular cells

follicular cells

cells that play a role in nourishing and protecting the egg

follicular cells

these cells clump up during the follicular phase that provides cushion and a protective layer for the egg

zona pellucida

thick, transparent and non-cellular layer composed of glycoproteins and provides structural support of the egg

zona pellucida

plays a crucial role in sperm-egg interaction during fertilization

the zona pellucida is triggered when the acrosome (a hydrolytic enzyme) is present. it hardens once it interacts or comes in contact with the acrosome to ensure only one sperm cell enters the egg

what is the mechanism of the zona pellucida vital for fertilization

100-300 million sperm cells

how many sperm cells in one ejaculation

vitelline membrane

innermost layer which is a think transparent membrane secreted by the egg itself

cytolysis/apoptosis

mechanism that takes place if the zona pellucida does not harden for fertilization; cell bursting

polyspermy

When the zona pellucida mechanism fails, multiple sperm can enter the oocyte which is called