RAT 21 Flashcards
what is the name of the process in which the female gamete is produced?
oogenesis
describe the stages of oogenesis and when each occurs.
- before birth: months 2-7 of the fetal period; oogonium undergoing mitosis formation of primary oocyte
- childhood to puberty: number of oocytes has dropped to ~ 300,000
- puberty to menopause: polar cell and secondary oocyte; fetilization occurs in this phase
when do the mitotic dividions take place in females?
before birth, during moths 2-7 of fetal development
between puberty and menopause, about how many primary oocytes are stimulated to continue development each month?
20-30
how many will complete development?
usually only one per month
what is the purpose of the polar body?
the smaller cell, first produced contains DNA but very little cytoplasm and often degenerates
what is the purpose of the secondary oocyte?
- contains DNA and most of the cytoplasm plus absorbed ECF
- cytoplasm ensures it will be fertilized
- potential to become an ovum
when does the secondary oocyte complete mitosis?
when it becomes fertilized
about how many primary oocytes are found in a newborn? about how many will reach maturity and ovulate?
- 1-2 million
- 400-500
why is this more complicated in females than in males?
- the structure of the gametes
- cytoplasm is needed to nourish the secondary oocyte
what is an ovarian follicle?
blister like structures in the ovarian cortex that mature along with the oocyte; where oocytes reside
what are the first follicles that formed called?
- primordial follicles
what do primordial follicles becomes as they mature?
primary follicles
what do primary follicles become as they mature?
secondary follicles
what happens to most primordial follicles?
stop maturing and instead die by atresia
what is the ovarian cycle?
a monthy series of cyclic hormone changes and events controlled by the HPG axis
how many follicles typically develop into a mature follicle each month?
one
what is the first phase of the ovarian cycle? when does it occur in a woman’s lifetime?
- follicular phase
- childhood to menopause
describe the primordial follicle
primary oocyte surrounded by a single layer of squamous follicle cells
describe the primary follicle. what is the shape of the granulosa cells?
- follicle cells become cubodial granulosa cells
- microvilli and thecal cells develop
- cubodial
describe the secondary follicle
- primary oocyte surrounded by multiple layers of granulosa cells
- follicular fluid found in small cavities around the oocyte
describe the vesicular (tertiary) follicle.
- primary oocyte finished meiosis I to become secondary oocyte
- surrounded by granulosa cells and fluid-filled antrum
- maturation of a primordial follicle to this stage takes ~ 350 days
typically, how many follicles become a tertiary follicle each month?
one
what is the name of the fluid-filled cavity?
antrum
in which type of follicle does the primary oocyte complete meiosis I to become a secondary oocyte?
vesicular follicle
in what phase of meiosis is the secondary oocyte suspended? when would it compelte meiosis?
- metaphase II
- when fertilization occurs
how long does it take for a follicle to mature into a vestivular follicle?
90-120 days
what is ovulation?
the process by which the ovary expels a secondary oocyte
the ovulated oocyte is in which stage of development?
stage 5
what typically happens to the ovulated oocyte?
taken to the uterine tube, moved toward the uterus
what happens if two follicles mature and both secondary oocytes are fetilized?
fraternal twins
what can lead to identical twins?
fertilization of a single oocyte by a single sperm, followed by the separation of the diving cellls in early development
what happens to the remainder of the follicle in the ovary after ovulation?
becomes the corpus luteum
what hormones are secreted by the corpus luteum?
- progesterone
- some estrogen
what happens to the corpus luteum if a pregnancy occurs?
persist for approximtely 3 months to produce hormones
what happens to the corpus luteum if a pregnancy does not occur?
begins to degenerate in ~10 days and stops producing horomones
what is the corpus albicans?
a whitish know of scar tissue
assuming a 28-day cycle, when does the follicular, ovulation, and luteal phase occur?
- follicular: 1-14
- ovulation: 14
- luteal: 14-28
do most women have a 28-day cycle? how does this vary?
- no: fewer than 25%
- anywhere form 21-40 days
which phase of the cycle is less variable?
luteal phase
what is the HPG axis?
the multi-tiered feedback loops of the hormones of the hypothalamus, anterior pituitary, and gonads
what is the first-tier control?
hypothalamas releases GnRH
what is the second-tier control?
GnRH stimulates the anterior pituitary to release FSH and LH
what is the third-tier control?
- the ovaries are the target of FSH and LH
- LH stimulates androgens
- FSH stimulates androgens conversion to estrogen
what are the effects of the HPG axis?
- estrogen stimulates a sominant follicle to mature to a vestibular follicle
- the new vestibulat follicle produces large amounts of estrogen, triggering and LH surge
- the LH surge and FSH trigger ovulation
what are some other effects of female hormones?
- estrongen
- maturation of the sex organs
- development of external genitalia
- maintanence of anatomical feature unique to
adult females
- progesterone
- maintaining pregnancy
what is the uterine cycle? what is another term for this cycle?
- the series of cycic changes that the uterine endometrium goes through each month as it responds to the fluctuating levels of ovarian hormones
- menstrual cycle
what is the endometrium?
the innermost tissue layer of the uterus composed of simple columnar epithelium
what is the stratum functionalis?
- functional layer
- undergoes cyclic changes in response to ovarian hormones
what is the stratum basalis?
- basal layer
- thinner, deeper; doesn’t thicken in response to ovarian hormones but forms a new stratum functionalis after mensturation ends
what are the spiral arteries?
uterine arteries that have branched several times
what are the three phases of the uterine cycle? when does each occur (given a 28-day cycle)?
- menstrual phase (days 1-5)
- proliferative phase (days 6-14)
- secretory phase (days 15-28)
what happens during the menstrual phase?
the uterus sheds the stratum functionalis, resulting in menstruation
what happens during the proliferative phase?
a new stratum functionalis develops with endometrial glands and spiral arteries and veins q
what happens during the secretory phase?
the spinal arteries convert the stratum functionalis to secretory mucosa and endometrial glands secrete uterine milk
what hormone is released if fertilization takes place? what is a major impact of this?
- human chlorionic gonadotropin (hCG)
- keeps the corpus luteum from degenerating and the progesterone level high
what changes occur in females during the secual response?
- vaginal mucosa, vestibule, and breasts engorge with blood
- clitoris and nipples become erect
- increase activity of vaginal mucosa lubricates the vestibule
what occurs during orgasm in females? do females have a refractory period?
- uterus exhibits peristaltic waves of contraction, and the cervix pushes down somewhat into the vagina
- not required for conception
- NO!
what hormonal changes occur during puberty?
- levels of estrogen and progesterone increase dramatically
- GnRH levels increase
list some female secondary characteristics.
- pubic and axillary hair
- increase in overall amount of adipose tissue in the subcutaneous layer, with additional deposits in the breasts, hips, and thighs
- increase secretions of sebacous glands
- skeletal changes: increased height and widening pelvis
what is menarche?
first episode of menstrual bleeding
what is female climacteric?
the time from the onset of irregular menstrual cycles to their complete cessation (may be up to 5 years)
what is menopause?
when menstruation has not taken place for at least one year
what changes in hormone levels occur during this time?
- low levels of estrogen and progesterone
- increased FSH and LH becuase they are no longer inhibited
what changes occur as a result of the chaging hormone levels?
- breasts, vagina, uterus, uterine tubes may shrink
- pubic and axillary hari may thin
- bone density decreases
- skin becomes thinner
why is sodium such an important osmotic particle in the ECF?
it is the most abundant extracellular cation
why is there such a steep sodium ion gradient between cytosol and ECF?
- the sodium-potassium pump
- the relatively low permeability of the plasma membrane to sodium ion
why is sodium critical to the function of excitable cells like neurons and muscle cells?
when sodium ion channels open, the sodium ions follow their concentration gradient and rush into the cell; causing depolarization
why is water balance dependent on sodium balance?
water reabsorption in the kidneys depends on a gradient consisting largely of sodium ions in the interstitial fluid
what two hormones increase sodium ion retention in the kidnes? how do they work?
- angiotensin-II: leads to increased sodium ion reaborption in the proximal tubule of the nephron
- aldosterone: releases from the adrenal cortex leads to increased sodium ion reabsorption from the distal tubules of the nephron
what hormones decreases sodium ion reabsorption?
ANP
what can cause a sodium ion imbalance?
anything that abnormally increases or decreases the number of sodium ions and/or the number of water molecules
why does the amount of water in the body affect the sodium ion concentration?
changes the concentration of sodium ions relative to water molecules
what is hypernatremia? what is the primary cause?
- sodium ion concentration in the blood above 145 mEq/L
- dehydration
what happens to cell in hypernatremia?
cells shrink
what are signs/symptoms of hypernatremia?
- dry mouth
- thirst
- dryness of skin
- decreased urine production
- fever
- organ function impaired
what is hyponatremia? what can cause hyponatremia?
- plasma sodium ion concentration less than 135 mEq/L
- overhydration OR hypersecretion of ADH
what are the signs/symptoms of hypoatremia?
- mental status changes
- seizure
- coma
how can hypoatremia be treated?
treated with hypertonic saline to restore the plasma sodium ion concentration and draw water back out of the cells
why is the steep concentration gradient of potassium ions critical to the function of neurons and muscle cells?
movement of potassium ions out of the cell down their concentration gradient through potassium ion channels is responsible for the repolarization phase of AP
what pump helps maintain the concentration gradient of potassium ions?
sodium/potassium pump
potassium ions are criticla in maintaining the ________________ potential
resting membrane
if potassium ion levels are critical, then why do you not die when you eat a banana?
due to deveral mechanisms including: insulin, aldosterone, and epinephrine
what hormone triggers the secretion of potassium?
aldosterone
what is hyperkalemia?
a plasma potassium ion concentration about 4.5 mEq/L
what happens to the RMP with mild/moderate hyperkalemia?
altered (more positive): the excess of potassium ions in the ECF causes fewer potassium ions to leave the cell
what happens with more severe hyperkalemia?
becomes so depolarized at rest that the cells are no longer excitable
what can cause mild hyperkalemia?
- renal failure
- aldosterone insufficiency
- widespread tissue damage due to severe burns or trauma
- drugs
what can cause severe hyperkalemia?
- ingestion
- administration of excess potassium ions
why are calcium and phosphate ions discussed together?
- they are found together in hydroxyapatite crystals
- inorganic portion of bone cannot be built unless both ions are present
simply put, what happens when the level of calcium ions in the ECF falls?
- calcium ions are released from the bone by osteroclasts
- more are reabsorbed from the flitrate in the kidneys
- more reabsorbed form ingested food and liquids in the small intestine
what happens when the level of calcium ion in the ECF rises?
- calcium ions are deposited into bone by osteoblasts
- fewer are reabsorbed from the filtrate
- fewer are absorbed from the small intestine
what two hormones regulate calcium and phosphate ion levels? what is the function of theses hormones?
- parathyroid hormone: triggers osteoclasts activity and calcium ion reabsorption in the kidneys; decreases reabsorption rate of phosphate ions; activation of vitmain D3
- vitamin D3 (calcitriol): potent stimulator of calcium ion absorption by the small intestine. increased osteoclast activity and calcium ion reabsorption from the kidney; triggers absorption of phosphate ions from the small intestine
what is hypercalcemia? what can cause hypercalcemia?
- a plasma calcium ion concentration above 10.5 mg/dL
- hyperparathyroidism, certain cancers, excess vitamin D, certain bone disorders, renal failure
what impact does excess calcium ions have on depolarization? why?
- diminsihes the ability of the neurons to depolarize
- because it makes neurons less permeable to sodium ions
what are signs/symptoms of hypercalcemia?
- decreased appetite
- constipation
- kidney stones
- bone pain
- frequent urination
what is hypocalcemia? how does this impact neurons?
- plasma calcium ion concentration lower than 8.7 mg/dL
- the neurons become hyperexcitable
what are some signs and symptoms of hypocalcemia?
- carpopedal spasm
- excessively long and strong muscle contractions
- sustained contractions
what are some important functions of chloride ions?
production of hydrochloric acid; secretion of bricarbonate ions from erythrocytes
chloride ion regulation is couple to the regulation of what other ion?
sodium
what is the pH range of body fluids, including blood?
7.35-7.45
what is a buffer?
resists changes in pH; prevents large changes in pH when an acid or base is added
what is a chemical buffer system?
chemical systems that work to buffer fluids in the body
what is a physiological buffer system?
functions of organ systems that work to buffer fluids
what are two physiological buffer systems?
- urinary system
- respiratory system
what are the two catergories of sources of acids adn bases in the body?
- those formed as a normal part of metabolic processes
- those ingested as part of the diet
what is the biggests source of metabolic acids?
carbon dioxide
do the acids and bases we consume in our food have a big impact on pH homeostasis?
no - they represent a very small minority
what assertion have been made by proponents of the alkaline diet?
- we all have blood that is too acidic due to out diets, and acid causes inflammation which causes disease
- alkaline diet is the core for every disease, up to and including cancer
is there any truth to these assertions?
- not really
- only that an alkaline diet would kill cancer cells
what is a strong acid?
acid that releases most of its hydrogen ions when placed in water
what is a weak acid?
- releases relatively few hydrogen ions in a soluton
- small impact on pH
what is a strong base?
binds and removes a great number of hydrogen ions from the solution
what is a weak base?
binds relatively few hydrogen ions in solution
which of these are found in a chemical buffer system?
weak acid and weak base
how does this minimize pH changes?
- weak base binds released hydrogen ions (from strong acid) and removes them from solution
- weak acid releases hydrogen ion to bind to released base ions (from strong base)
what is the equation for the carbonic acid-bicarbonate ion buffer system?
CO2 +H20 – H2CO3 – HCO3- + H+
what happens if a strong acid is added to a solution of pure water?
acid immediately donates its hydrogen concentration and therefore reduces its pH
what happens if a strong acid is added to a buffered solution?
hydrogen from the strong acid is accepted by the bicarbonate ion, forming carbonic acid
what happens if a strong base is added to a solution of pure water?
released hyroxide ions remove many of the hydrogen ions from the solution and increases its pH making it very basic
what happens if a strong base is added to a buffered solution?
- releases bicarbonate and hydrogen ions into the solution
- hydrogen binds to the hydroxide ion released from sodium hydroxide, forming water and a molecules of sodium bicarbonate
normally the amount of carbon dioxide expired is the same as the amount of ___________________
carbon dioxide produced by metabolic reactions
why does your respiratory rate increase when you are exercising and decrease when you are sedentary?
- exercising: glycolytic catabolism and oxidative catabolsim occur more rapidly and more CO2 is generated
- sedentary: you generate less CO2 so your respirate rate decreases
what happens to hydrogen and bicarbonate ions that are formed in the reaction above?
- hydrogen bind to hemoglobin, which buffers the cytosol of erythrocytes
- bicarbonate: transported into the plasma, where they buffer fixed acids
what are the two basic ways that the kidneys aid in acid-base balance?
- kidneys can excrete fixed acids that the lungs cannot excrete
- control the concentration of bicarbonate ions in the blood
the kidneys remove hydrogen ions by the process of ___________________ in the proximal tubule
secondary active transport
what percentage of bicarbonate ions are typically reabsorbed?
100%
