Chapter 20 Reproduction Flashcards
What is Gametogenesis
Spermatogenesis (sperm) and oogenesis (egg)
Gonadotropic hormones are
FSH
LH
Gonadal steroids are
Testosterone,
Estradiol
Progesterone
Accessory reproductive organs are
Ducts
Glands
Each pair of chromosomes contains…
two homologous chromosomes
Where is DNA contained
in these 46 chromosomes
What is a diploid cell
Cell that contains 46 chromosomes
What is a haploid cell
Cell that has half the chromosomes (23)
What type of division is seen from zygote into an adult
Mitosis
What are 1-22 pairs known as
Autosomal chromosomes
What is pair 23 known as
Sex chromosomes
What is the three hormone sequence
- Hypothalamus secretes GnRH
- Anterior pituitary gland secretes FSH and LH
- Gonads stimulated to secrete sex hormones and undergo gametogensis
What is unique about the secretion of gonadotropins and sex hormones in females
It is cyclical
Menstrual cycle
What causes negative feedback in this three hormone sequence
Inhibin
Sex hormones secreted by gonads
What functions are involved in the Testes
Gametogenesis (spermatogenesis)
Synthesis and secretion of hormones
What are the two main structures in the Testes
What is located in each
- Seminiferous tubules
Sertoli cells = spermatogenesis and secretion of inhibin - Leydig cells
Testosterone
What parts are involved in the duct system of the male reproductive system
Epididymis
Vas deferens
Ejaculatory ducts
Urethra
What secretes components of semen
Seminal vesicles
Prostate
Bulbourethral glands
List the pathway of sperm
Tubules Rete testis Efferent ductules Epididymis Vas deferens
Seminiferous tubules are located in the
Testis
What does FSH initiate
Spermatogenesis
Secretion of inhibin by Sertoli cells
What does LH stimualte
Leydig cells to secrete testosterone
What is testosterone (3)
What happens to the levels during puberty
- Major androgen
- Allows for spermatogenesis
- Stimulates anabolism = growth of muscles
Increased = growth of accessory organs
Where does spermatogenesis occur
In the Seminiferous tubules
List the stages of spermatogenesis
- Mitosis = spermatogonia divide into primary spermatocytes
- First meiotic division = two secondary spermatocytes
- Second meiotic division = spermatids
- Spermiogenesis = spermatids turn into spermatozoa
What are Sertoli cells
support spermatogensis and protect developing sperm
What is the head of the sperm called
Acrosome
What does the sperm do at the point of fertilisation
The acrosome releases enzymes that allow the entry of the ova
What are the 3 structures of the penis
Glans = sensory nerve endings
Erectile tissue:
Corpus spongiosum
Corpora cavernosae
What is semen
Sperm + fluids from testes
What can cause urine flow to be blocked
Enlargement of: Epididymis Seminal Vesicles Bulbourethral gland Prostate gland
What happens during an Erection (3)
Release of NO from parasympathetic axons
Increases blood flow into corpora cavernosae and corpus spongiosium
Increase length and width and increase pressure
What happens during emission (2)
Movement of semen into urethra
Stimulated by sympathetic nerves = muscle contraction
What is ejaculation
Forcible expulsion of semen from urethra out of penis
Stimulated by sympathetic nerves = muscle contraction
What are some causes of erectile dysfunction
Nerve damage Heart disease Large prostate Drugs Diabetes Psychological factors
What are the treatments for erectile dysfunction
What do they do
Viagra
Cialis
Increase cGMP to promote vasodilation
What occurs in the ovaries
Gametogenesis
Synthesise and secretion of hormones
Ovarian cycle
What hormones are produced and secreted in the ovaries
Estrogen
Progesterone
Inhibin
What happens during the ovarian cycle
Follicles go through a developmental sequence
Ovulation of one ovum plus follicular cells per month
What are the accessory organs of the female reproductive system
Fallopian tubes
Uterus
Vagina
The Uterus has 3 layers which are
Perimetrium = outermost layer/connective tissue
Myometrium = thick smooth muscle layer
Endometrium = epithelial layers that are taken off during menstruation
What are the external genitalia
Clitoris
Labia majora
Labia minora
What is the clitoris
Erectile tissue (similar to penis)
What is the labia majora
Erectile tissue
What is the labia minora
Vestibule which opens:
Urethra
Vagina
What releases the Ovum
Ovary
What moves the Ovum to the oviduct
Fimbrial contactions
Oviduct ciliary escalator
Where are fertilized eggs implanted
Uterus
What must a sperm move through in order to get to an ovulated egg
Cervix and Uterus
Oogenesis (follicle growth) stimulated by
Stimulated by FSH
What are oogonia
What do they undergo
Primitive germ cells
Undergo mitotic division during fetal life
What happens at 7 month of gestation
Mitosis ends
Oogonia enter 1st meiotic division as Primary oocytes
What are Primary oocytes surrounded by
What do they do
What are the combination of primary oocytes and the surrounding matter known
as
Granulosa cells
Secrete hormones
Primordial follicle
What may happen to primary follicles
May develop more into secondary follicles
What happens when there is continued growth of secondary follicles
What do they contain
Graafian follicle (mature)
Contains fluid filled cavity known as antrum
What is made when the follicles divide by meiosis
Secondary oocyte
Where are secondary oocytes contained
Graafian follicle
When does the second meiotic division occur
Upon completed fertilisation
The steps of Oogenesis are (5)
Primary follicle Secondary follicle Graafian follicle First meiotic division Secondary oocyte
What is the Zona Pellucida
What does it do
Thin layer in the secondary oocyte
Barrier to fertilisation
Steps of Ovulation (3)
Day 10-14 = follicle becomes graafian follicle
Bulges on surface of ovary
Ruptures = releasing oocyte into oviduct = ovulation
What is the secondary oocyte surrounded by (2)
Zona pellucida
Corona radiata
What is a zygote
Fertilised egg
What is the “yellow body”
Corpus luteum
How long is the menstrual cycle
28 days
Menstruation is
the shedding of epithelium of endometrium if egg is not fertilised
What are the 3 phases of the menstrual cycle
The days of each
Follicular phase (Days 1-13)
Ovulation (day 14)
Luteal Phase (days 15-28)
What happens during follicular phase (4)
- FSH causes development of follicles
- Granulosa cells increase estradiol production
- One follicle matures to graafian follicle
- LH surge prior to ovulation due to rapid increase in estradiol
What happens during ovulation (3)
- Estradiol = LH surge
- LH surge causes wall of graafian follicle to rupture
- Secondary oocyte is released from ovary into oviduct
What happens during luteal phase (4)
- Transformation of follicle into corpus luteum due to LH
- CL secretes estradiol and progesterone
- Negative feedback of FSH and LH secretion
- Estrogen and progesterone decrease during luteolysis
Ovulation is provoked by a surge in
LH
Luteolysis occurs when there is
a decrease in LH
Follicular maturation is caused by which hormones
This results in the synthesis of
FSH and LH
Ovarian steroid hormones
When is the proliferative phase (5-14) during
What happens in this phase
Follicular phase
Growth and maturation of endometrium under influence of estradiol from follicle
When is the secretory phase (15-28) during
What happens in this phase
Luteal phase
Increased progesterone and estradiol from CL stimulate endometrial thickening and uterine gland development for implantation
What happens during the menstrual phase (1-4)
4
- Ovarian hormone secretion decreases
- Uterine blood vessels constrict = depriving tissue of blood
- Endometrium undergoes necrosis = menstrual flow
- Myometrium contracts = causes cramps
What are the different phases of the endometrial cycle
Menstrual phase (1-4) Proliferative phase (5-14) Secretory phase (15-28)
Where is mature sperm stored
Epidiymis
What is capacitation
Ability to fertilise egg
Where does fertilisation occur
In the oviduct
Due to short viability and slow transport of egg
What is the time window
5 days before - 1 day after
What is the Acrosome reaction
Acrosome binding to zona pellucida of egg
Stages of early development
- Zygote completes second meiotic division
- Second polar body disintegrates
- Undergoes cleavage
- Continued mitosis = morula
- Becomes blastocyte
- Implantation
What is Cleavage
Mitotic cell division into 2 smaller cells
What is a morula
8 cells at 50-60 hours after fertilisation
What is a blastocyst
Inner cell mass (fetus) + outer chorion (placenta)
What is implantation
Occurs on day 21 of menstrual cycle
Blastocyst attaches to uterine wall
What allows the blastocyst to attach to the wall of the endometrium
Trophoblast cells - sticky
What do chorion cells of blastocyst secrete
What does it do
Human chorionic gonatropin (hCG)
Maintains CL and secretion of estradiol + progesterone by placenta
Prevents menstruation
What does the placenta secrete to maintain pregnancy
Progesterone and estrogen
What separates fetal blood from maternal blood
Chorionic villi
Where do umbilical arteries transport blood
Where does the blood then go
From fetus into capillaries of chorionic villi
Blood then exits capillaries to travel back to the fetus via umbilical vein
Where are the umbilical arteries and veins housed
Umbilical cord
What is an early indicator of pregnancy
The presence of chorionic gonadotropin in the urine
Where is the fetus located
Fluid filled amniotic sac
What is Parturition
Childbirth
What stimulates uterine contractions
Oxytocin and Prostaglandins
What does progesterone do during labor
Keeps smooth muscle inactive
What does estrogen do during labor
Stimulates myometrial contractions
What does increasing estrogen cause during labor (3)
Smooth muscle cells to form gap junctions
Myometrium becomes single unit
Increases number of receptors for oxytocin and prostaglandins
Cervix is made soft and flexible
What does relaxin do
Aids estrogen and prostaglandins relax the cervix
What is the sequence that leads to labor (6)
- FETAL hypothalamus begins to secrete CRH
- Secretion of CRH by placenta
- CRH causes FETAL anterior pituitary to secrete ACTH
- ACTH causes fetal and maternal adrenal cortex to secrete cortisol
- MOTHER hypothalamus stimualtes posterior pituitary to secrete oxytocin
- Labor contractions
What does cortisol do during labor
- Stimulates surfactant production in FETAL lungs
- Inhibits placental progesterone
- Increases prostaglandins in uterine smooth muscle to stimulate contractions
What hormones cause the breasts to develop
Estrogens and progesterone
What glands produce and secrete milk
What is this process known as
Mammary glands
Lactogenesis
What is the secretory unit in mammary glands
Alveolus
What surrounds the breast
Myoepithelial cells and adipose cells
What hormone increases after parturition
What does it stimulate
Prolactin
Mammary glands to produce milk
What also causes the secretion of prolactin
What other hormone is also secreted because of this cause
What is the end result
Sucking
Oxytocin
Secretion of milk into ducts and ejection of milk from nipple
Oxytocin is released from where
What does it cause in the breast
Prolactin is released from where
What does it cause in the breast
Posterior pituitary
Milk ejection
Anterior pituitary
Milk production