Human reproduction

functions of male reproductive system

produce and store sperm, deposit sperm in the female reproductive system

makeup of male reproductive system

primary sex organs - testes

ducts - epididymis, vas deferens, urethra

accessory glands - seminal vesicles, prostate, cowpers

external genetalia - penis

function of scrotum

temperature regulator, protects the testes

function of testes

produce sperm and testosterone

composition of seminiferous tubules

interstitial cells (cells of leydig), Sertoli cells, lumen, spermatogonium

functions of cells in testes

cells of leydig - produce testosterone

sertoli cells - produce proteins and nutrients for sperm during spermatogenesis

spermatogonia - divide to form sperm

spermatogenesis def.

events during which mature, haploid sperm are produced from the germinal epithelium in the seminiferous tubules of the testes. produces 400 million sperm per day, not all of which are functional.

phases of spermatogenesis

Multiplying, growth, reduction, differentiation

multiplying phase description male reproduction

diploid spermatogonia of the germinal epithelium divide to form new spermatogonia

growth phase description male reproduction

some spermatogonia mature and grow in size to develop into primary spermatocytes

reduction phase description male reproduction

first meiotic reduction division, each diploid primary spermatocyte forming two haploid secondary spermatocytes. Spermatocytes undergo second meiotic division, resulting in four haploid spermatids

differentiation phase description male reproduction

spermatids lose cytoplasm and unnecessary cell organelles and differentiate into immature sperm.

epididymis structure

formed by joining of semeniferous tubules into a highly convoluted tubule

epididymis function

sperm maturation and storage

vas deferens fuction

transportation of mature sperm to the urethra

accessory glands function

secrete fluids that enter the urethra which aid the sperm on it's journey to the egg

individual glands functions

cowper's - nutrilises acidity from vagina and urine residue in the urethra. Provides lubrication for penis tip during intercourse

seminal vesicles - provides nutrients for sperm to make ATP (fructose and proteins)

Prostate - alkaline fluid to protect sperm from acidic conditions, lower female immune response to semen, provides lubrication and nutrients

penis structure

made of a spongey tissue which expands and contracts by filling and emptying of blood

penis function

deliver sperm during sexual intercourse into the vagina

distinctions of the human penis

no erectile bone, relies on engorgement for an erection, not attached to the abdominal wall and hangs freely

composition of female reproductive system

primary reproductive organ - ovaries

accessory organs - fallopian tubes, uterus, vagina

external genitalia - vulva

structure of ovaries

surrounded by a germinal epithelium layer with primary follicles containing immature eggs embedded in the outer layer

function of ovaries

formation and release of eggs, production of oestrogen and progesterone

oogenisis def.

production of haploid, mature eggs in follicles of the ovary

multiplying phase description female reproduction

before birth, germ cells from the germinal epithilium sink in and divide by mitosis to form primary follicles. Each follicle contains a diploid oogonium surrounded by a theca (single layer of cells)

growth phase description female reproduction

from puberty, primary follicles start periodically growing and developing to form a graafian follicle, oogonium grows into a primary diploid oocyte

reduction and maturity phase description female reproduction

primary oocyte undergoes meiosis undergoes meisosis to form a haploid egg, as the other three haploid polar bodies degenerate. Mature graafian follicles move periodically to the surface of the ovary, where they burst, releasing the mature egg and surrounding follicle cells (ovulation)

fallopian tubes structure

muscular tubes lined with cilia, ending in an infundibulum with fingerlike outgrowths (fimbria)

fallopian tubes function

pathway between ovary and uterus for egg,sperm and zygote.

site of fertilisation and initial cell division of the egg

enable egg/ developing zygote to move towards the uterus by action of muscles and cilia

uterus structive

single, simple cavity comprised of external myometrium and internal endometrium

uterus function

• organ in which blastocyst implants

• contraction of myometrium enables baby to be pushed out during birth under presence of hormone oxytocin

cervix function during pregnancy

maintaining pregnancy by the sphyncter muscles of the cervix keeping the uterus closed during pregnancy to avoid a miscariage

vagina structure

muscular passage between uterus and outside of body with elastic, folded walls and an acidic pH

vagina fuction

place where sperm are deposited, forms a birth canal for baby during birth

clitoris function

small mass of erectile tissue which plays a role in sexual excitement of the female

puberty def.

the process of physical and physiological changes during which a person becomes capable of reproduction

adolescence

the period of physical, physiological and psychological changes

hormones released to begin puberty

males= ICSH

female = FSH

changes to females during puberty

breast developement, pubic/ body hair, widening of hips, menstrual cycle, growth spurt

changes to males during puberty

enlargement of testes and penis, pubic/ body hair, increase in size of larynx, sperm production begins, growth spurt, acne

cycles in the menstrual cycle

ovarian, uterine

phases of ovarian cycle

development of Graafian follicle, ovulation, formation of the corpus luteum

Graafian follicle phase description

1. under influence of FSH, primary follicles develop into a fluid filled Graafian follicle

2. primary oocyte undergoes meiosis, developing into a haploid egg cell

ovulation description

1. Graafian follicle matures and enlarges, moving to the surface of the ovary

2. Mid cycle, lutenising hormone is released from the pituitary gland, causing the Graafian follicle to rupture, releasing the egg cell

formation of corpus luteum description

1. After ovulation, Graafian follicle under the influence of FSH and LH changes into a glandular tissue known as the corpus luteum and begins to produce large amounts of progesterone

uterine cycle description

1. oestrogen secreted by maturing follicles start the repair of the endometrium (day 6-14)

2. endometrium thickens, becoming vascular and glandular, now suitable for implantation of a blastocyst

menstruation description

high levels of oestrogen and progesterone inhibit the release of FSH and LH, causing the corpus luteum to degenerate and progesterone levels to drop, shedding the lining of the endometrium.

menstruation cycle steps

1. under influence of FSH a primary follicle develops into a graafian follicle, causing the ovaries to produce oestrogen

2. oestrogen stimulates pituitary to release LH

3. LH causes ovulation, and the graafian follicle develops into the corpus luteum and begins to secrete progesterone

4. pituitary stops secreting FSH/LH to to high oestrogen/ progesterone levels

5. oestrogen and progesterone levels drop, causing the corpus luteum to wither

6. Menstruation occurs

7. Low levels of oestrogen cause pituitary to start releasing FSH and the cycle restarts

cause and effects of menopause

the ovaries stop producing oestrogen and progesterone, meaning no ovulation or menstruation

effects of menopause

hot flushes, mood changes, atrophy of reproductive organs, bone mass loss, increased risk of cardiac disease

copulation def.

the transfer of sperm into the vagina of the female when the male penis is inserted

Fertilisation def

fusion of the sperm nucleus with the egg nucleus to form a diploid zygote

gestation def.

the time between conception and birth during which the embryo and then foetus develope in the uterus

stages of prenatal development

fertilisation, blastocyst implantation, embryo formation, foetal stage

early development description

1. fertilisation occurs in the fallopian tube as the DNA of the male and female gametes fuse to form a zygote

2. Diploid zygote begins to divide by mitosis, each cell deviding repeatedly to form the MORULA

3. morula develops into a blastocyst, with the outer cell wall forming the trophoblast

4. after a few days in the uterus, blastocyst sinks into the thickened, vascular endometrium

difference between a foetus and a embryo

embryo refers to developing zygote before 8 weeks. After organ development it is known as a foetus

placenta development/ structure

develops from chorion with villi penetrating the endometrium, each villi containing a cappilary network to allow nutrients and oxygen to move between maternal and foetal blood by diffusion. connects foetus with mother via the umbilical cord

placenta functions

1. oxygen, glucose, animo/fatty acids, ions and vitamins pass from maternal blood to foetal blood

2. foetal waste passed into maternal blood for excretion

3. transport of maternal antibodies

4. acts as a micro filter to ensure no pathogens or drugs pass into the foetal blood system

pathogens able to pass through the placenta

syphilis and HIV

placenta endocrine function

1. after 3 months, placenta begins secreting progesterone and oestrogen, taking over from the ovaries and corpus luteum

2. Secretes relaxin later in pregnancy to relax joints and ligaments to assist in delivery of baby

functions of amnion

temp control, hydration, protection from mechanical harm

amnion structure

a membrane that surrounds the developing embryo, secreting amniotic fluid that fills the amniotic cavity

amniocentesis

a produce used to determine if a baby will be born with chromosomal abnormalities by using the amniotic fluid to see the baby's genetic information

amniotic fluid functions

1. supports developing foetus, allowing freedom to move and preventing malformation due to gravity and pressure

2. cushions protects foetus from external injury

3. medium in which to practice breathing and swallowing movements

4. holds urine released from foetus

5. protects against changes in temperature and dehydration

structure of umbilical cord + function

1. two umbilical arteries that carry deoxygenated fetal blood, carbon dioxide and other waste products to the placenta;

2. one umbilical vein that carries oxygen and nutrients ( such as glucose and amino acids) acquired from the mother into the fetus

first trimester length and changes

first 12 weeks with hormonal changes