Reproductive System Flashcards
What are the functions of the reproductive system?
Secretion of sex hormones
Production of gametes
Production of offspring
How many pairs of chromosomes do humans have?
23, for a total of 46
How many sets of chromosomes does a somatic cell have (and by the way what is a somatic cell?)
Two: 1 maternal, 1 paternal aka diploid (2n)
A somatic cell is any cell except gametes
How many chromosomes do gametes have?
23, they are haploid (n)
True or False: Gametes in a pair are identical
False. They are equivalent, they code for the same characteristics but one is maternal one is paternal
What is the term for the fusion of a sperm cell and egg cell?
Fertilization is the process
Zygote is the cell
What kind of cell is a zygote?
Diploid (2n)
What is the purpose of meiosis I?
To reduce the number of original chromosomes in half to prepare for fusion
What creates a unique set of chromosomes for each gamete?
Recombination aka Scrambling
True or false. Gametes do not go through Interphase prior to meiosis
False. They do
What happens in Prophase I of meiosis I?
Duplicates centriole pairs pair up forming tetrads
Crossing Over occurs: homologous chromosomes exchange equivalent segments
What does crossing over mean? When/How does it occur and what does it create?
Homologous chromosomes exchange equivalent segments
Occurs between non-sister chromatids during Prophase I
Creates a new chromosome that has some maternal and some paternal parts
What happens during Metaphase I?
Homologous chromosomes align in the center of the cell by miotic spindles
They are pulled apart into two separate cells
Independent Assortment - the side each chromosome lines up on is independent of other pairs
What happens during Anaphase I?
Homologous chromosomes are separated and move to opposite poles
What happens during Telophase I?
Two haploid (n) cells are formed
What happens during Telophase II?
Cytokinesis occurs and a total of 4 cells containing gametes (n) are made
What is the difference between the purpose of mitosis versus the purpose of meiosis?
Mitosis - Cell duplication to increase cell numbers. Makes sure cells stay the same.
Meiosis - Gamete production, produces genetic variation
When does synapsis occur? What is synapsis?
Prophase I of Meiosis. This is the process where two homologous chromosomes line up, allowing for crossing over
What are the 3 factors contributing to Genetic Recombination?
Crossing Over
Independent Assortment
Random Fertilization
How many possible genetic combinations are possible before crossing over?
n^23 means 8 million combos in each gamete
8mil x 8mil = 64 trillion possible combinations
What is gametogenesis?
The production of gametes. Begins in embryonic glands while in utero (amniotic life)
Where foes spermatogenesis take place?
In the seminiferous tubules in the testis, within sustentacular cells aka Sertori cells
What is the difference between spermatogenesis and spermiogenesis?
Spermatogenesis - Process if sperm cell production
Spermiogenesis - Spermatid maturation
When does spermatogenesis start?
Puberty, continues throughout life
What is the function of spermatogonia?
Goes through mitosis on the basal lamina at the blood-testicular barrier. For every one that goes through meiosis one remains behind to duplicate
What is important about the blood-testicular barrier?
Sperm cells are considered foreign by the body. If they crossed the barrier the immune system would develop antibodies for them
What are secondary spermatocytes?
Tetrad-containing cells (4 haploids not 2 diploids)
What happens in spermiogenesis?
Spermatids change shape, losing most of the cytoplasm and organelles
What are the hormonal effects of GnRH during spermiogenesis? What are the negative feedback loops?
GnRH > FSH > Sertoli cells > ABP increases spermatogenic cells’ ability to bind to testosterone
GnRH > LH > Leydig cells (aka interstitial cells) > testosterone production
FSH produces inhibin, which decreases FSH secretion
high testosterone levels decreases LH and GnRH secretion
What are the accessory male sex glands and their contribution to semen?
Seminal Vessicles - Left and Right, posterior base of bladder, 60% of volume. Rich in fructose
Prostate Gland - Base of bladder, 30% of volume, Alkaline solution to protect sperm from acidic environment of the vagina
Bulbourethral glands - beneath prostate on either side of membranal urethra. Alkaline fluid to neutralize urethra
What is semen?
A transport medium that protects and activates sperm
What do prostaglandins do?
Decrease cervical mucous viscosity and stimulates reverse peristalsis in the uterus
How much semen is ejaculated versus how much sperm?
2-5ml
Contains 20-150 million sperm
What are the anatomical characteristics of the penis?
Contains a urethra and 3 cylindrical bodies of erectile tissue
The corpus spongiosum expands to keep urethra open
The corpora cavernosa keeps the penis erect
What is the difference between the two phases of male sexual response?
Erection - Enlargement and stiffening of erectile tissue with blood. Vasodilation of corpus cavernosa is caused by PSNS
Ejaculation - Propulsion of semen by SNS
What are the two parts of ejaculation?
Emission - ducts and accessory organs rapidly contracting, bladder sphincter constricts
Expulsion - Muscles at the base of the penis undergo rapid contractions
What happens in utero concerning oogenesis?
All oogonia complete mitosis and become primary oocytes, they begin meiosis but arrest at prophase I
How many oocytes complete meiosis I?
About 400/250,000 primaries present at puberty
What is the primordial follicle?
A layer of simple squamous cells surrounding primary oocytes
What happens during puberty concerning oogenesis?
A primordial follicle becomes a primary follicle (cuboidal cells), which enlarges when antrum expands with fluid to become a Graafian follicle (these cells will become corpus luteum after expulsion of secondary oocytes
How is a secondary oocyte made?
A primary oocyte is activates and completes meiosis I but its unequal distribution of cytoplasm causes production of a secondary oocyte and a first polar body
True or false. All secondary oocytes go through meiosis ii
False. They only complete meiosis II if they are fertilized, otherwise arrest at metaphase II and are ovulated
What happens when an ovulated secondary oocyte is fertilized?
A sperm cell merges with it and it completes meiosis II, yielding a secondary polar body and one large ovum
How many genomes are in a daughter cell?
1
How many chromatids are in each chromosome?
2
What has to happen to chromosomes before cell division?
Replication
How many gametes are in a cell at the end of each metaphase?
Metaphase I: 1
Metaphase II: 1
How many chromatids per chromosome in a cell during each metaphase?
MetPhase I: 4
Metaphase II: 2
How many chromatids per chromosome in a finished gamete? How many genomes?
1
How many types of gametes result from a 2n cell with X chromomoes?
2n to the n/2 power
ie 4=2 squared = 4, 6 = 2 cubed = 8, 46 = 2 to the 23rd = 8 trillion
How many chromosomes would a human gamete have that resulted from meiosis with non-disjunction of one of the chromosome pairs?
22 or 24
What percentage of female ova will have X chromosomes?
100%
What percent of male sperm will have Y chromosomes?
50%. 50% will have X
If neurons can’t divide, what type of cells produce brain tumors?
Glial cells
What term refers to all the gene alleles one has?
Genotype
What terms refers to all expressed alleles?
Phenotype
What are different versions of the same gene?
Alleles
What kind of chromosome contains alleles, with one gene on each chromosome in the pair?
Homologous
In order for an individual to express a recessive trait, what must be true about that individual?
They must have a homozygous chromosome with two recessive alleles
When does chiasmata (crossing over) occur?
Metaphase I and prophase I
What kind if genetic variation produces the uniqueness seen by the combination of a particular female and particular make gamete?
Random fertilization
What is a permanent transmissible change to the DNA coding sequence caused by environmental factors?
Mutation
What kind of genetic variation causes various combinations of homologous chromosomes from paternal and maternal lineage within a haploid cell?
Independent Assortment
What kind of inheritance most often results in a recessive trait, expressed more often i. males than in females?
Sex-Linked Recessive Inheritance
What kind of inheritance results in continuous phenotype variations between two extremes (ex. skin color)
Polygenic Inheritance
Blood type is the result of what kind of inheritance?
Multiple Allele Inheritance
Sickle cell anemia is an example of this kind of inheritance, where heterozygote had an intermediate between a homozygous dominant and a homozygous recessive?
Dominant-Recessive
What kind of inheritance is expressed only in the absence of a dominant gene, ig albinism?
Incomplete Dominance
What is an autosomal codominant allele?
Neither gene is dominant over the other and both are expressed
What two events happen during Prophase I?
Maternal and paternal DNA get mixed
Nuclear envelope starts to break down
What pituitary hormone stimulates interstitial cells to make testosterone?
LH
What hormone affects sustentacular cells to make inhibin and anti-Mullerian hormone?
FSH
What is ABP important for?
Increasing spermatogenic cells’ ability to bind to testosterone
At what stage of meiosis do chromosomes align in the spindle equator in homologous pairs?
Metaphase
Primary oocytes are haploid or diploid?
Diploid
Secondary oocytes are haploid or diploid?
Haploid
Follicles rely on a steady supply of what hormone to develop?
Estrogen
Developing follicles produce what hormone?
Estrogen
What hormone exerts a negative feedback loop on LH production in oogenesis?
Inhibin
When estrogen levels reach a certain concentration it exerts a positive feedback on LH production, causing what?
An LH surge, followed by ovulation
What cells directly surround an oocyte in the secondary and vesticular follicles?
Thecal cells
What is the the remnant of the vesticular follicle after ovulation called? What foes it secrete?
The corpus luteum; progesterone
What hormone increases during the follicular (proliferative) phase?
Estrogen?
What happens during ovulation?
A secondary oocyte is expelled from the ovary where it is swept by fimbriae into the Fallopian tubes to be implanted in the uterine wall
When are ovarian hormones at their lowest?
The beginning of the menstrual phase, this is what triggers menstruation
What causes embryonic female ducts to disappear in a male embryo?
Anti-Mullerian hormone
What is the female copulatory organ?
Vagina
What is the vestibule?
The recess containing the opening of the vagina and uterus
What secretes mucus to lubricate the vaginal opening?
The greater vestibular gland
What moves oocytes or a fertilized ovum toward the uterus?
Uterine tube
What is the process of developing haploid sperm?
Spermatogenesis
What is the process by which sperm grow and develop?
Spermiogenesis
What stores sperm and moves it to the ductus deferens?
Epididymis
What transports semen out of the penis?
The utethra
What gland secretes an alkaline substance with anticoagulants?
Prostate gland
What stores sperm and moves it to the ejaculatory duct?
Ductus deferens
The absence/presence of what protein/gene causes sec determination?
SRY, on the Y chromosome
What are the bipotential tissues, what do they become?
Genital tubercle> gland penis/clitoris
Urethral groove/fols > shaft of penis/labia minora
Labioscrotal fold > shaft of penis & Scrotum/labia majora
Gonad cortex> —/Ovaries
Gonad Medula > Testes/—
When is the functional zone of the endometrium restored?
The proliferarice phase of menses
The process of spermiogenesis produces what?
Soermatozoa
True or false: Semen contains prostaglandins, seminal fluid, fibrinogen, and spermatogonia.
False. Spermatozoa, not spermatogonia
What form if sexual differentiation results in short stature, a broad cheat, webbed neck, CV/kidney disorders, and female genetalia?
Turner’s Syndrome
What form of sexual differentiation results in tall stature. female contours, breast development, male genetalia, and infertility?
Klenifelter’s
Both male and female genetalia are present in what sexual abnormality?
True hermpahoditism
In what sexual differentiation do the gonads match the chromosomal sex but external genetalia are the opposite?
Psuedohermamphroditism
During what phase of menstruation is progesterone dominant?
Secretory phase
During what phase of menstruation does cervical mucus get thinner?
Proliferative phase
Are all of the following statements true?
-Oogenesis begins before birth
-Ova develop from stem cells called oogonia
-By birth females have already lost about 80% of embryos
Yes
A rise in blood levels of FSH at the beginning of the ovarian cycle is responsible for what?
Follicle maturation
How does ejaculation happen?
Sympathetic stimulation causes
peristaltic contractions of the the ampulla and contractions of the bulbospongiosus muscle
A primary spermatid matures into how many spermatids?
4, each containing 23 chromosomes
