Biology 30 Unit D - Human Reproduction

scrotum (2)

* the sac that contains testes and epididymis
* provides lower temperature (necessary for sperm development)

testes(2)/testis(1) ((4))

* full of **seminiferous tubules**
* coiled ducts (\~250m in length) where immature sperm cells (**spermatogonia**) undergo mitosis and meiosis
* where sperm cells are created all through a mans life
* **interstitial** **cells** that produce **testosterone**

meiosis

is division of cells with a reduction of chromosomes 46 → 23

mitosis

is cell division

spermatogonia

immature sperm cells

epididymis(s)/epididymides(pl) (4)

* sits on top of the testes
* the sperm travels here from the seminiferous tubules
* **sperm maturation happens here**
* where sperm becomes ‘ready to swim’ is stored

vas deferens(s)/vasa deferntia (pl) (2)

* tubes that carry sperm from epididymis → urethra
* at the end of the vas deferens they’re 3 glands that together with sperm form semen (**seminal** **fluid**)

vasectomy (2)

* cutting of the vas deferens to provide permanent sterilization


* ejaculation still occurs but no sperm is released

glands that contribute to semen

seminal vesicle, prostate gland, cowper’s gland

seminal vesicles (2)

* (2) produces **fructose** → energy for sperm
* produces **prostaglandins** → causes a chemical signal which causes smooth muscle contractions (inside the female’s body) to help move sperm

prostate gland (4)

* (1) walnut-size gland that produces an **alkaline** (basic pH) **buffer** against vaginal acidity
* swells during arousal to help stop the passage of urine
* during ejaculation. a sphincter also helps shut urine passage


* prostate gland produces some mucous

how would you detect prostate cancer? (2)

little droplets of pee, prostate swelled

cowper’s glands

(2) mucus-rich fluid which is believed to protect sperm from acid of the urethra

penis (4)

* contains 3 spongy columns which fill w/ blood upon sexual arousal
* **erect** → arteries dilate/veins constrict
* **flaccid** → arteries constrict/veins dilate
* the urethra runs through the middle of the penis (carries semen or urine but never both)

glans penis

the enlarged tip where the urethra opening is contains many sensory nerve endings

foreskin (2)

* covers the glans
* retracts during ejaculation + can be surgically removed (**circumcision**)

ejaculation (4)

1. semen collects in the ejaculatory duct seconds b4 ejaculation
2. the parasympathetic nervous system causes the erection
3. sympathetic nervous system causes muscles to contract (orgasm) sending \~5mL of semen out of the urethra
4. once sperm mix with glandular secretions they have **24-72 hours to live**

semen

contains of \~500M sperm and is the secretions from 3 glands

journey for sperm

(**seven** **up**) Seminiferous Tubules, Epididymis, Vas Deferens, Ejaculatory Duct, Urethra, Penis

sperm structure (4)

* **HEAD** contains the **nucleus** (**DNA**) of the cell, tip contains the **acrosome**.
* **MIDPIECE** contains mitochondria (4 energy) + microtubules (4 structural support)
* **TAIL** contains whip-like **flagella** that propel sperm

acrosome (3)

* contains enzymes that are released when sperm comes in contact with the egg
* enables sperm to penetrate the egg
* 100’s sperms are required to release their enzymes in order to soften egg enough to get one sperm inside

t/f: sperm are all genetically identical

false; each sperm is genetically diverse so no 2 kids look exactly the same even if from the same parents (besides identical twins)

sperm development (4)

* in order to occur, spermatogonia (immature sperm cells) must continuously divide (**mitosis**)
* since babies are combinations of mom and dad’s DNA, # of chromosomes need to be cut in half (meiosis)
* 2 divisions result in 4 cells (23 chromosomes per cell)
* spermatids (produced @ the end of meiosis) take time to develop → mature sperm

movement of sperm during spermatogenesis (2)

* as sperm develop they move from the basement membrane (outermost part) of seminiferous tubules → lumen (inside)
* when the sperm have developed they're released into inside of tubules where they go through collecting ducts into **epididymis** 4 **storage**

sertoli cells (3)

* found in seminiferous tubules
* provide nourishment to the growing sperm
* tucks them away safe so they can’t be **destroyed during infection**

GnRH (3) (m)

* from hypothalamus
* stimulates releases of **FSH** and **LH** from the pituitary
* **high levels of testosterone inhibits GnRH**

what inhibits GnRH? (m)

high levels of testosterone which stop FSH release

FSH and LH are known as (m)

**gonadotropic** hormones

FSH (follice stimulating hormone) (m) (4)

* from pituitary
* stimulates **Sertoli cells to aid in spermatogenesis**
* ****must have FSH for sperm production (SSS - FSH stimulates Sertoli cells to make sperm)**
* **inhibin** has a negative feedback on **FSH**

what has neg feedbck on FSH?(m)

inhibin

Luteinizing hormone (LH) (3) (m)

* from pituitary
* stimulates interstitial cells to produce testosterone
* **testosterone** has a negative feedback on **LH**

what has neg feedback on LH? **(m)**

testosterone

inhibin (3) (m)

* from sertoli cells
* stops pituitary from releasing FSH
* **released when sperm count is high/FSH is high to cause ng feedback (not released when low counts)**

testosterone (5)

* from interstitial cells responsible for stimulating spermatogenesis
* causing the development of primary and secondary sex characteristics
* needs LH to simulate the release of this
* this has neg feedback on GnRH and LH

Which two hormones are directly responsible for the production of sperm?

testosterone and FSH

primary sex characterstics

chars that distinguish one sex from another that directly relate to sex cell production

male primary sex characteristics (2)

* testes and all other structures related to production and release of sperm
* begins developing b4 birth

secondary sex characteristics

any other physical or behaviour characteristics that appear @ puberty + differentiate sexes w/o having direct reproductive function

male secondary sex characteristics (4)

* pubic, axillary, facial hair
* voice change (larynx growing)
* muscles strengthen + develop
* increase secretions of body oils (acne

gestation period

time period a woman is pregnant (approx. 9 months)

embryo (2)

* what a baby is called 0-3 months of gestation period
* **most of development occurs during this stage.**

diploid cells (2)

* (2n) - somatic or non-sex cells that contain pairs of chromosomes that are inherited from the parents
* contain 46 chromosomes

haploid cells

gametes that contain half the number of chromosomes that diploid cell has and is produced during **meiosis** in the **GONADS**

gametes

haploid sperm cells and egg cells

why do somatic cells contain the exact same chromosomes?

because of mitosis

fertilization (2)

* when **coitus** occurs and the sperm travels to the Fallopian tube to fertilize an egg
* **fertilization** is the union of gametes nuclei producing a diploid cell called a **zygote**

coitus

sexual intercourse when the male releases semen into the female vagina

fraternal twins (4)

* when a woman releases two eggs that are fertilized
* **2 different eggs fertilized by 2 different sperm**
* **2 different zygotes = different DNA**
* essentially siblings born at the same time.

cleavage (2)

* stages a zygote undergoes by dividing through mitosis
* each of the “daughter” cells produced from the original zygote has identical DNA due to mitosis

identical twins (2)

* this happens if the zygote cells separate during cleavage
* **1 egg, 1 sperm, 1 zygote that splits to separate but identical zygotes (identical DNA)**

conjoined twins

identical twins that failed to completely separate

morula (2)

* by the time the zygote is just approaching the uterus, it becomes a cluster of cells called this
* this stage starts at the 16-cell stage and continues to until the ball of **cells begins to hollow**

blastocyst (3)

* by the time the zygote **implants into the endometrium**, its formed a hollow ball of cells called this
* **chorion** **cells** - single layer of cells that’ll eventually form the chorion
* **inner** **cell** **mass** - forms the embryo

implantation (2)

* \~day 6
* in order to implant into the endometrium, the outer layer of blastocyst (chorion cells) must secrete **enzymes** to digest the wall of the endometrium

male causes of infertility (3) (APO)

* abnormal sperm production or function
* problems with delivery of sperm
* overexposure to certain chemicals and toxins

female causes of infertility (5) (POUEF)

* ovulation disorders
* uterine/cervical abnormalities
* fallopian tube damage or blockage
* endometriosis
* primary ovarian insufficiency (early menopause)

in virto fetliziation (3)

* a woman takes fertility drugs to produce a large number of eggs
* the eggs are retrieved from follicles via needle
* the egg and sperm are mixed in a dish and the embryo is implanted into the uterus

hCG (4)

* a few weeks after conception, the chorion cells from the embryo begin secreting this hormone
* keeps the corpus lutem from disintegrating
* **maintains endometrium due to estrogen and progesterone**
* pregnancy tests check for the presence of **this**

what happens as the inner cell mass develops?

the **AMNIOTIC CAVITY** forms **on** top of the **YOLK SAC** and in between the two layers is where the embryo forms as the embryonic disc

gastrulation

begins on 16th day of pregnancywhen the embryonic disc folds in on itself forming a gastrua which is the 3 germ layers

cell differentiation

division of the cells into the three germ layers

endoderm (2)

inner layer

* forms **digestive system, repspitary system and endocrine glands**

ectoderm (2)

outer layer

* **forms nervous system, skin, hair**

mesoderm (2)

middle layer

* **forms muscles, bones and reproduction organs**

morphogensis

as the cells differentiate and reorganize themselves the embryo begins to develop its shape

what happens on the 7th week of pregnancy in males (3)

* **SRY GENES** on the Y chromosomes tell the gonads to become testes
* **testes** secrete testosterone and male development occurs
* without the SRY gene the embryo will develop as a female

chorion membrane (3)

* the outermost membrane that is derived from **chorion cells and surrounds the embryo**
* grows **chronic villi** which give rise to the **placenta**
* **chorion** secretes **hCG** to maintain corpus luteum in the first trimester

amnion membrane (4)

* inner membrane which encases the embryo and secretes amniotic fluid surrounding the embryo
* provides protection from shock
* babies breathe and swallow for practice
* protects baby from temp changes in mom

allantois (3)

* forms blood vessels for the umbilical cord
* contributes to blood vessels of the placenta
* collects urea and contributes to the formation of the bladder

extra embryonic membranes

chorionamnionyolk sakallontis

placenta (4)

* organ that facilitates circulation between mother and baby (embryonic and maternal parts)
* the **embryonic** part contains chronic villi where only fetal blood circulates
* **maternal** is made up of blood capillaries in the endometrium where mother’s blood circualtes

**fetus and mother blood never mix**

ubilicol cord (4)

* connects embryo to chorion and **later connects fetus to placenta**
* contains **1 vein and 2 arteries** that carry fetal blood back and forth
* arteries carry wastes and carbon dioxide
* veins carries nutrients and o2

when does the fetus develop?

* last two trimesters
* growth occurs
* placenta produces it’s **own estrogen and progesterone so hCG stops being secreted and corpus lutem stops functioning**

parurtion

labour, delivery of the fetus and delivery of afterbirth

hormones in labour (4)

1. starts by the fetal pituitary releasing **ACTH**
2. **ACTH** stimulates the fetal adrenal gland to secrete cortisol to release **prostaglandins** in the placenta
3. **prostaglandins** release **oxytocin** which causes contractions. **Oxytocin** is also stimulated by pressure on the cervix
4. **relaxin** is secreted to loosen the pelvic ligaments and open the cervix

estrogen and progesterone in labour (3)

* estrogen stimulates **contractions** and progesterone **inhibits** them
* **several days before labour progesterone levels drop allowing estrogen to stimulate ACTH and cortisol release**
* both drop at birth

high oxytocin causes (2)

* causes contractions
* the head pressing on the cervix causes higher (of this hormone) which causes the head to press on the cervix **(postive feedback**)

low progesterone causes

contractions

stages of labour (3)

1. dilation: begins with contractions, rupturing of amnion, and dilation of cervix
2. expulsion - birth of baby
3. placental stage - begins after birth when the placenta is expelled

lactation

* hormone prolactin stimulates milk production
* sucking action of baby stimulates oxytocin and milk is squeezed into the ducts
* as long as baby sucks more milk will produce and release **(positive feedback)**

ovaries (3)

* two ovaries (one on each side)
* where the egg (ova (pl.)/ovum (sing.)) are found/made
* responsible for the production of female sex hormones estrogen and progesterone

where are estrogen and progesterone produced?

ovaries

fallopian tube/oviduct (4)

* ovum is released into the oviduct (\~1 every 28 days), where fertilization occurs
* wide openings from ovaries are called fimbriae (pl.)/fimbria (sing.) which helps eggs enter the fallopian tube


* the egg must be fertilized in the fallopian tube in \~48 hours or it dies
* once fertilized the zygote (fertilized egg) travels to the uterus

zygote

fertilized egg

ectopic pregnancy

if the zygote gets stuck and grows in the oviduct

tubal ligation

a surgical procedure where the fallopian tubes are cut and tied off and provides permanent sterilization. (tubes tied)

uterus/womb (6)

* where the baby develops
* fertilized ovum have 3-5 days to get to the uterus from the fallopian tube and implant
* **myometrium** - outer muscular layer (where muscle cramps happen)
* **endometrium** - glandular inner lining which’ll nourish the embryo
* **mensuration** is shedding of endometrium when no embryo implants

myometrium

outer muscular layer (where muscle cramps happen)

endometrium (2)

* glandular inner lining which’ll nourish the embryo


* **mensuration** is shedding of endometrium when no embryo implants

mensuration

shedding of endometrium when no embryo implants

vagina (3)

* connects the uterus with the outside environment
* very acidic - creates a hostile environment for dangerous micoorgnamisms
* vagina has a flora of useful microorganisms that help defend the body

cervix (2)

* muscular band which separates vagina from uterus


* holds the baby in place so it cannot enter the vagina

pap test

provides doctors with a sample of the cervical epithelial cellsdoctors check for cancerous cells (and STI’s if necessary)

female mnemonic

(**off u evil crazy vampire**) Ovary, Fimbriae, Fallopian tube, Uterus, Endometrium, Cervix, Vagina

what happens to a females eggs when she reaches puberty? (2)

* she would have decreased the number of eggs she had by half (400K)
* the eggs are now **primary oocytes**

menopause

when a woman reaches the end of her childbearing years she goes into this and no longer produces eggs or menstruates

primary oocytes (2)

* first oocyte in the follicle and the eggs after **menarche**
* contains 46 chromosomes

menarche

start of a girls first menstrual cycle

immature eggs

oogonia

what do ovaries contain? (3)

* ovaries contain fibrous connective tissue and small groups of cells called **follicles**
* (inside the follicle) the **primary** **oocyte** undergoes reduction division in meiosis I to decrease to 23 chromosomes and **become a secondary oocyte**
* granulosa cells help nourish the developing oocyte