Reproduction Flashcards
What are gametes
Eggs or sperm
What are gonads
The primary sex organs (ovaries or testes)
What are the male external genetalia
Testes and scrotum
What is the scrotum
A fold of skin the encloses the male gonads
What does the scrotum do
Maintaind the tested at a cooler temperature than the abdominal cavity
What happens if testes do not descend into scrotum
The higher body temperature causes infertility and requires surgery to lower them
What are the testes
Paired organs that develop from gonads in the abdomen of a fetus
When do the testes descend
Last 2 months of fetal development
What do seminiferous tubules do
Produce sperm by meiosis called spermatogenisis
What do seminiferous tubules contain
Interstitial cells that produce testosterone
What happens to seminiferous tubules in puberty
Before puberty they are solid cords and the hollow out and become functional in purberty
What is the function of the epididymis
A place if sperm maturation and storage of sperm
What are the epididymis
Tightly coiled tubules just outside the testes
What is the vas deferens
A tubule that connects from the epididymis to the ejacalutory duct
What is the function of the vas deferend
Takes mature sperm from epididymis to ejaculatory duct that connects to urethra
Beginning also stores sperm for a short time
What is the function of the urethra
It carries both urine and semen
During ejaculation the bladder is closed off so no urine comes out
What is the urethra
A tube that allows urine (waste) and semen to exit through the penis
Where is sperm produced
Inside the seminiferous tubules in the testes
Where does sperm mature
In the Epididymis
Where does mature sperm enter into
Into the vas deferens by muscle contractions
What is the path of sperm in the body
Seminiferous tubules - epididymis - vas deferens - ejaculatory duct - urethra - penis
What are the 3 parts of the sperm
The head, middle piece and tail
What shape is the mitochondria in the sperm
Spiral shaped
What does the mitochondria do in the sperm
It surrounds the middle piece and provides energy for sperm movement
What does the acrosome cap do
Its located on the head of the sperm with enzymes needed to penetrate the outer barriers of the egg
What is located in the sperm head
Acrosome cap and 23 chromosomes in nucleus
What is the function of the sperm tail
To help the sperm move/swim
How many sperm are produced, reach egg, penetrate egg
100 million produced per ejaculation, less than 100 reach egg, 1 penetrates
What is the function of sperm
To move and carry genetic information to the egg
What do the three parts of the sperm contain
Head: nucleus w/ 23 chromosomes and acrosome cap w/ enzymes
Middle piece: spiral mitochondria
Tail: just the tail
What is the penis
A cylindrical shaped organ that hangs in-front of the scrotum
How does erection occur
Increased blood flow that fills the spongy tissue in the penis
What is semen
A thick white fluid containing sperm and secretions from three organs
What are the three contributory glands to semen production
Seminal vesicles
Prostate gland
Bulbourethral glands
Where are the seminal vesicles
Between the bladder and rectum, joins the vas deferens
Two seminal vesicles join two vas deferens
What do seminal vesicles do
Release fluid that contains nutrients for sperm and prostaglandins to trigger uterus contractions to cause sperm movement
Where id the prostate gland
Surrounds the urethra below the bladder
What does the prostate gland do
It adds an alkaline base to buffer sperm against the acidity of vagina (base is 7.5ph)
Helps sperm survive
Where is the bulbourethral gland
Just below the prostate gland
What does the bulbourethral gland do
Adds lubrication from fluid to help sperm movement
How does the hypothalamus control the testes
By secreting GnRH
What does GnRH do
It triggeres the anterior pituitary to produce two hormones
FSH and ICSH
What does FSH do
Promotes sperm production in seminiferous tubules
What does ICSH do
Controls the production of testosterone by interstitial cells
What is testerone
The male sex hormone
What does testosterone do
-Necessary for sperm maturation
-Growth of beard and other hair
-Larynx and vocal cord enlarging
-Stimulating muscle growth
-Increasing sex drive and aggressiveness
-Stimulates sweat and oil glands causing acne and odor
What does anabolic steroid cause damage to
Kidneys and circulatory system
What is the function of the female repoductive system
To produce and deliver the female gamete and to provide an environment for the developing fetus
Where are ovaries located
To each side of the uterus in the pelvic abdominal cavity
What are ovaries
The female gonad containing follicles at various stages of maturation
What does an ovary do
Produces eggs and sex hormones
What is oogenisis
The maturation of 1 follicle oocyte per month
What is ovulation
The process by which the oocyte bursts from an ovary and usually enters the fallopian tube
Where are estrogen and progesterone produced and released
At the ovaries
How big are ovaries
3cm by 1cm
Where are oviducts (fallopian tubes) located
They extend from ovaries to uterus
What do the oviducts do
They sweep up eggs from ovary using cilia lining and wafting fimbria
Transport embryo
Also site of fertilization
What are fimbriae
Fingerlike ends of the oviducts that sweep up eggs from ovary
How long does an oocyte live if fertilization does not occur
6-24 hours
What is the uterus
A thick walled muscular organ for nurturing and embryo (where fetus develops)
Where is uterus located
Above and slanted forward over urinary bladder
How wide does uterus stretch
5cm to 30cm wide
What are the three layers of the uterus
An inner layer of spongey endometrium filled with blood vessels
Middle layer of thick smooth muscle
Outer layer of connective tissue
What do the three layers of uterus do
Inner - expelled in menstruation or placenta formation
Middle - delivers baby, expels endometrium, assists passage of sperm
Outer - holds organs in place
Where is cervix located
Back of vaginal canal, contains opening to uterus
Function of cervix
Opens to release endometrium, deliver baby, or let sperm in
Acts as a barrier to many microbes with many wbc nearby (usually is closed)
What is the vagina
A muscular tube with mucosa lining
What is the clitoris
Organ infront of the urethra that becomes erect from blood
What is labia
External folds to protect external genetalia
What does hypothalamus secrete
GnRH
What does GnRH do
Triggers anterior pituitary to produce FSH and LH
What does FSH do
Stimulates follicles in ovary to produce eggs
What do ovaries secrete
Estrogen and progesterone
What are the two cycles that occur in female mammals
The ovarian and uterine cycle
What is a follicle
A small fluid filled sac located in the ovaries or follicle cells that contains an immature egg or oocyte
How many follicles does a female have
2 million reduced to 350k-400k at puberty
How many follicles mature in a females life
Around 400 because a female produces one oocyte per month during reproductive years
What do remaining follicle cells in the ovary develop into
Corpus luteum (degenerates after 10 days)
What does the corpus luteum produce
Progesterone and some estrogen
How is an oocyte matured in ovulation
follicle cell surrounds primary oocyte as follicle matures. Follicle becomes a secondary follicle and oogenesis continues. Primary oocyte become secondary oocyte after maturing and is released in ovulation.
What are the 3 phases to the ovarian cycle
Follicular phase
Ovulatory phase
Luteal phase
What are the events in the follicular phase
Several follicles begin to grow and one matures
FSH which is produced by the anterior pituitary stimulates follicular development in ovary
Causes increased estrogen and progesterone
As estrogen rises negative feedback occurs of FSH secretion and phase comes to an end with ovulation
What are the events in the ovulatory phase
The ovary wall ruptures and a follicle is released into the oviduct (ovulation)
Estrogen levels spike and GnRH is secreted from the hypothalamus, causes LH to increase, this causes ovulation
^ positive feedback
What happens in the luteal phase
LH promoted the development of the corpus lutem (empty follicle)
Corpus luteum secretes progesterone and estrogen
As progesterone rises, negative feedback lowers secretion of LH
Corpus luteum degenerates due to low LH
Progesterone drops at end of luteal face because corpus luteum degenerated (menstruation begins)
^ when fertilization does not occur
What are the hormone levels in the follicular phase
FSH is initially high before being inhibited by estrogen production
What are the hormone levels in ovulation
Theres a huge spike in LH levels (and FSH)
Hormone levels in luteal phase
Estrogen and progesterone rise and inhibit FSH and LH
Hormone levels in menstruation
Estrogen and progesterone fall and FSH rises
How long is the menstrual cycle
20-40 days average of 28 days
What generates the uterine cycle
Estrogen and progesterone
What are the three phases of the uterine cycle
Menstruation
Proliferate phase
Secretory phase
What happens in menstruation
Low levels of estrogen and progesterone cause menstrual bleeding
(Loss of endometrium), blood vessels rupture
What happens in the proliferate phase
The remaining endometrium regenerates, thickens, and becomes more vascular until ovulation
Due to increased estrogen made by a new ovarian follicle
When does ovulation occur on the uterine cycle
On day 14/28
What happens in the secretory phase
A rise in progesterone by corpus luteum makes endometrium thicken more
Uterine glands mature and secrete thick mucus due to production by corpus luteum
Uterus readies to recieve developing embryo
If not pregnant corpus luteum degenerates and lower hormone levels cause uterine lining to break down
Where does fertlized egg begin developing
As it travels down oviduct to uterus
Where does the embryo embed
Into the endometrial lining
What does the placenta form from
Maternal and fetal tissues
What does placenta do
Provides exchange of molecules between fetal and maternal blood
Placenta makes HCG to prevent degeneration of corpus luteum
What happens when the placenta is developed
Estrogen and progesterone are produced to maintain the endometrium lining of the uterus and shut down anterior pituitary so no new follicles mature
Because endometrium is maintained no occurs
What is present in urine during pregnancy
HCG
What hormones involve trigger of childbirth
Prostaglandins and oxytocin from mothers pituitary
What hormones involve trigger of childbirth
Prostaglandins and oxytocin from mothers pituitary
Where is oxytocin made and stored
Made in the hypothalamus and stored in the posterior pituitary
What does oxytocin do
Causes uterus to contract and induces labour, also stimulates release of milk
Involves a positive feedback loop
When does menopause occur
Between the ages of 44-55
What is menopause
The period in a womans life where the ovarian and uterine cycles stop
What happens in menopause
The ovaries become unresponsive to FSH and LH and no longer secrete estrogen or progesterone
Uterine cycle becomes irregular
After a year of no menstruation menopause is considered complete
