RAT 21

What is hypocalcemia? How does this impact neurons?

A plasma calcium ion concentration lower than 8.7 mg/dl is considered to be hypocalcemia. The condition is generally due to a decrease in PTH, ineffective PTH (as occurs with renal failure), and vitamin D deficiency, although many other factors can contribute to it. Hypocalcemia has the opposite effect on neurons from hypercalcemia—the neurons become hyperexcitable, as more sodium ions enter and depolarize the neurons, stimulating action potentials.

Describe the primordial follicle.

A single layer of squamous follicular cells surrounds the primary oocyte. At birth, each ovary has approximately 1-2 million primordial follicles, each follicle containing a primary oocyte.

What is a chemical buffer system?

Chemical buffers are, as the name suggests, chemical systems that work to buffer fluids in the body -a system that resists changes in the pH of the body's fluids; consists of a weak acid and its conjugate base

What happens when the level of calcium ions in the ECF rises?

Conversely, when the calcium ion level rises, calcium ions are deposited into bone by osteoblasts, fewer are reabsorbed from the filtrate, and fewer are absorbed from the small intestine.

What happens to cells?

Although hypernatremia can impact the depolarization of excitable cells, its most immediate, obvious effects are due to the osmotic imbalances that it causes. As occurs in most cases of dehydration, water moves out of the cell into the hypertonic ECF, leading to a reduced volume of cytosol and to cell crenation. This affects cells throughout the body, and can lead to the same symptoms we listed for dehydration. Treatment revolves around restoring hydration, which will normalize the sodium ion concentration.

What is menarche?

Approximately 2 years after the onset of puberty, females experience their first episode of menstrual bleeding, called menarche

What changes occur as a result of the changing hormone levels?

As a result, ovulation does not occur and the blood concentration of estrogens declines sharply, although many women continue to synthesize some estrogen from adrenal androgens. However, secretions of FSH and LH from the pituitary are no longer inhibited, so these hormones may be continuously released for some time. The lower concentration of estrogens and progesterone may change the female secondary sex characteristics. The breasts, vagina, uterus, and uterine tubes may shrink, and the pubic and axillary hair may thin. Often bone density decreases, which may lead to osteoporosis, and the skin becomes thinner.

What impact does excess calcium ions have on depolarization? Why?

As we discussed earlier, an elevated calcium ion concentration in the ECF makes neurons less permeable to sodium ions, which diminishes the ability of the neurons to depolarize. This in turn decreases the neurons' activity, leading to mental sluggishness, reduced reflex activity, and weak muscle activity (due to lack of stimulation from motor neurons).

What changes occur in females during the sexual response?

During sexual excitement, the vaginal mucosa, vestibule, and breasts engorge with blood; the clitoris and nipples become erect; and increased activity of the vaginal mucosa and vestibular glands lubricates the vestibule. For the most part, these events are similar to the erection phase in men. Tactile and psychological stimuli, mediated along autonomic pathways, promote sexual excitement.

What happens during the menstrual phase?

During the menstrual phase, the uterus sheds the stratum functionalis, resulting in menstruation.

What is the name of the process in which the female gamete is produced?

Female gametes are produced by the process of oogenesis. -oogenesis: the process of female gamete, or ova, production in females Oogenesis begins with an oogonium that has 46 chromosomes, and produces 1 secondary oocyte that has 23 chromosomes; when fertilized, this secondary oocyte becomes an ovum with 46 chromosomes.

What happens if a strong base is added to a solution of pure water?

For example, see what happens when a strong base such as sodium hydroxide (NaOH) is added to water, as shown in the upper right illustration in Figure 25.9b. In this unbuffered solution, the released hydroxide ions remove many of the hydrogen ions from the solution and raise its pH, making it very basic

If potassium ion levels are critical, then why do you not die when you eat a banana?

Fortunately, several mechanisms within the endocrine and urinary systems help to prevent this from happening. For one, hormones such as insulin, aldosterone, and epinephrine stimulate the uptake of potassium ions by cells. This shifts the newly ingested potassium ions into the intracellular compartment.

What do they become as they mature?

From childhood through menopause, primordial follicles progressively mature first to primary follicles

Assuming a 28-day cycle, when does the follicular, ovulation, and luteal phase occur?

Assuming an ovarian cycle of 28 days, the follicular phase extends from the 1st to the 14th day of the cycle, ovulation typically occurs on day 14, and the luteal phase extends from the 14th to the 28th day.

What changes in hormone levels occur during this time?

It takes place because the number of primary follicles left to respond to FSH and LH is quite low after approximately three decades of ovarian cycles and also because of atresia—a process in which immature follicles degenerate and are resorbed during the follicular phase of the menstrual cycle. Those follicles that remain in the ovaries are less responsive to gonadotropins, and so less estrogen and progesterone are secreted.

What is the ovarian cycle?

This cycle consists of three main phases: the follicular, ovulation, and luteal phases.

Why is sodium such an important osmotic particle in the ECF?

This is due in large part to two factors: (1) the Na+/K+ ATPase pump, which uses ATP to pump sodium ions out of the cytosol against their concentration gradient; and (2) the relatively low permeability of the plasma membrane to sodium ions, which prevents these ions from leaking back into the cytosol in large numbers. This high extracellular concentration of sodium ions makes them one of the most important types of osmotic particles in the ECF.

What hormone triggers the secretion of potassium?

This makes potassium ion secretion possible only in the distal tubule and collecting system. As you have learned, this is under the control of aldosterone, which triggers secretion of potassium ions (and hydrogen ions) and reabsorption of sodium ions.

Alkalosis is defined as a body fluid pH greater than 7.45 (alkalemia refers specifically to an elevated blood pH).

This occurs when more base ions are added than the buffers can handle or when the number of hydrogen ions in the body fluids decreases. Alkalosis increases the excitability of neurons, and so they fire action potentials inappropriately. This results in sensory symptoms such as numbness and tingling and motor symptoms such as muscle twitches or tetanic contractions. Untreated, alkalosis can lead to seizures and death due to sustained contractions of respiratory muscles.

What percentage of bicarbonate ions are typically reabsorbed?

This process accounts for reabsorption of nearly 100% of the bicarbonate ions in the filtrate and secretion of large numbers of hydrogen ions.

Review: this section begins with a list of calcium functions. How many do you remember from previous chapters? Jot down the functions that you forgot about.

Main components of osseous tissue 🡪 give bone its hardness and resistance to compression Required for muscle contraction and plateau phase of cardiac action potential/intracellular signaling Blood clotting Neuronal synaptic transmission etc.

What can cause mild hyperkalemia?

Mild hyperkalemia is generally the result of renal failure or aldosterone insufficiency. It may also be due to widespread tissue damage that occurs with severe burns or trauma, as the damaged cells rupture and release their potassium ions into the ECF. Other potential causes include drugs such as aldosterone blockers and one commonly used for heart failure

What happens if a strong acid is added to a buffered solution?

Now see what happens when we add the same acid to a solution buffered by sodium bicarbonate, shown at the bottom left in Figure 25.9a. Notice that here (after sodium bicarbonate dissociates), the hydrogen ion from the strong acid is accepted by the bicarbonate ion, forming carbonic acid. Since carbonic acid is a weak acid, it doesn't release its hydrogen ions as readily, minimizing any pH changes in the solution.

What are the spiral arteries?

Numerous endometrial (uterine) glands change in length as endometrial thickness changes. The main vascular supply of the uterus comes from the uterine arteries, which arise from the internal iliac arteries in the pelvis. After branching several times, they eventually form the spiral (coiled) arteries of the stratum functionalis.

What is the purpose of the polar body?

Polar body: the smaller cell that is produced during meiosis of oogenesis; contains DNA but very little cytoplasm and generally does not divide further - extra set of DNA is discarded in the polar body

What is the HPG axis?

Regulation of ovarian function requires a rhythmic fluctuation of hormones from the hypothalamus, the anterior pituitary, and the ovaries themselves. These hormones interact via negative feedback in the same hypothalamic-pituitary-gonadal (HPG) axis that operates in males, with the exception of a positive feedback mechanism that triggers ovulation.

Normally the amount of carbon dioxide expired is the same as the amount of _______________

Under normal conditions, the amount of carbon dioxide expired by the lungs matches the amount of carbon dioxide produced by metabolic reactions, which is why your respiratory rate doesn't remain constant.

How many will complete development?

Usually one primary oocyte (or more in some women) will complete meiosis I to produce two haploid cells that are very different in size.

What happens if two follicles mature and both secondary oocytes are fertilized?

Usually only one vesicular follicle is at the peak of maturation when ovulation occurs; however, sometimes more than one vesicular follicle releases a secondary oocyte. This phenomenon may result in fraternal twins, or nonidentical twins. It occurs more commonly in some families and also increases in frequency with advancing maternal age.

In which type of follicle does the primary oocyte complete meiosis I to become a secondary oocyte?

Vesicular (tertiary) follicle: -At this point, the primary oocyte, which has been suspended in prophase I, completes meiosis I to form the secondary oocyte and the first polar body.

Why are calcium and phosphate ions discussed together?

We cannot discuss calcium ions without also discussing phosphate ions (PO43−)(PO4 3−) because they are found together in hydroxyapatite crystals. The inorganic portion of bone cannot be built unless both ions are present.

What is hyperkalemia?

a plasma potassium ion concentration above 4.5 mEq/l. Hyperkalemia is arguably one of the most dangerous electrolyte imbalances; indeed, a high dose of potassium ions can cause death almost immediately.

What is an ovarian follicle (this may be called simply "follicle" in this chapter)?

a small structure inside the ovarian cortex that contains a developing oocyte

What is hypernatremia? What is its primary cause?

a sodium ion concentration in the blood above 145 mEq/l. The most common cause of hypernatremia is actually dehydration.

What is a strong acid? A weak acid?

a strong acid is one that releases most of its hydrogen ions when placed in water, which lowers the pH of the solution. A weak acid, however, releases relatively few hydrogen ions in solution, and so has a much smaller impact on pH.

What is a strong base? A weak base?

a strong base is one that binds and removes a great number of hydrogen ions from the solution, increasing the solution's pH. A weak base binds relatively few hydrogen ions in a solution and so has less impact on its pH.

What is a buffer?

buffer system: a chemical system that resists changes in pH and prevents large swings in the pH when acid or base is added to the solution

What is second-tier control?

Second-tier control. GnRH stimulates the anterior pituitary to release FSH and LH.

How long does it take for a follicle to mature into a vesicular follicle?

So it will take about 90-120 days for the dominant follicle to mature to a vesicular follicle with a secondary oocyte.

What happens to the corpus luteum if a pregnancy occurs?

So, if pregnancy does occur, the corpus luteum will persist for approximately 3 months to produce hormones.

What is the biggest source of metabolic acids?

The biggest source of metabolic acids is carbon dioxide, which is a byproduct of glucose catabolism -carbon dioxide is known as volatile acid because in solution it is able to change states from carbonic acid back to carbon dioxide gas. This allows carbon dioxide to be eliminated from the body through both the lungs and the kidneys.

What happens if a strong base is added to a buffered solution?

The hydrogen ion binds to the hydroxide ion released from sodium hydroxide, forming water and a molecule of sodium bicarbonate. The bicarbonate ion is a weak base and will not remove significant numbers of hydrogen ions from the solution.

What pump helps maintain the concentration gradient of potassium ions?

primarily to the actions of the Na+/K+ pump

What is the ovarian cycle?

the monthly series of events associated with the maturation of an ooctye and its follicle in an ovary -at puberty, a female begins the ovarian cycle

What is the purpose of the secondary oocyte?

The larger cell, the secondary oocyte, contains DNA and most of the cytoplasm plus absorbed extracellular fluid. The extra cytoplasm in the secondary oocyte ensures that if it is fertilized, it will have adequate nutrients for its 4- to 7-day journey toward the uterus. The large amount of cytoplasm is also the reason why only the secondary oocyte has the potential to become an ovum.

What is the pH range for body fluids, including blood? (You should know these numbers!)

The normal hydrogen ion concentration of body fluids is equal to a pH range of about 7.35-7.45. The body must maintain the pH within this narrow, slightly alkaline, range because even a slight deviation can have disastrous consequences for our cells. Blood pH is maintained through a number of mechanisms, the most important of which are the respiratory system, the urinary system, and the body's buffer systems.

The kidneys remove hydrogen ions by the process of ______________ in the proximal tubule.

The proximal tubule cells secrete hydrogen ions from fixed acids by a secondary active transport process.

About how many primary oocytes are found in a newborn? About how many will reach maturity and ovulate? *****

The remaining 1-2 million oogonia begin to undergo meiosis I, at which point they are called primary oocytes. Of a woman's 300,000 primary oocytes, only about 400-500 will become mature secondary oocytes during her reproductive lifetime.

Do most women have a 28-day cycle? How does this vary?

However, fewer than 25% of women normally have 28-day cycles, and cycles as short as 21 days or as long as 40 days are relatively common. In addition, it is also common for the same woman to experience 1- or 2-day fluctuations from one cycle to the next.

In what phase of meiosis is the secondary oocyte suspended? When would it complete meiosis?

However, it is then suspended in metaphase II and will not complete meiosis unless fertilization occurs.

What happens to most primordial follicles?

However, most of these follicles stop maturing and instead die by a process called atresia (ah-TREE-zee-ah), during which the oocyte first dies, followed by the collapse of the follicle. Indeed, by the time puberty is reached, the number of follicles has fallen by 50-90%.

What happens with more severe hyperkalemia?

However, with severe hyperkalemia, the membrane can become so depolarized at rest that the cells are no longer excitable. In effect, this shuts down every excitable cell in the body, including neurons and muscle cells, and the result can be nearly instantaneous death.

What happens if a strong acid is added to a solution of pure water?

The upper left illustration in Figure 25.9a shows a strong acid, such as hydrochloric acid, being added to a beaker of water. Notice that the acid immediately donates its hydrogen ions to the solution, which increases its hydrogen ion concentration and therefore reduces its pH.

What is the uterine cycle? What is another term for this cycle?

The uterine cycle, or menstrual cycle, is the series of cyclic changes that the uterine endometrium goes through each month as it responds to the fluctuating levels of ovarian hormones. These uterine changes are coordinated with the levels of estrogen and progesterone released during the phases of the ovarian cycle, which are controlled by FSH and LH released from the anterior pituitary.

What are some important functions of chloride ions?

Their high concentration in the ECF makes them an important osmotic particle, along with sodium ions. Chloride ions are also a critical component of some other processes, including the production of hydrochloric acid secreted by the stomach. In addition, chloride ions are involved in the secretion of newly formed bicarbonate ions from erythrocytes.

This is the most important chemical buffer system! You should know the chemical equation showing the conversion of carbon dioxide to bicarbonate ion!

There are three main chemical buffer systems in the body: the carbonic acid-bicarbonate ion buffer system, the phosphate buffer system, and the protein buffer system.

What is hyponatremia? What can cause hyponatremia?

Hyponatremia is defined as a plasma sodium ion concentration less than 135 mEq/l. Like hypernatremia, hyponatremia is often not related to the absolute number of sodium ions but, rather, is due to overhydration. One cause of hyponatremia with overhydration is hypersecretion of ADH, a condition known as syndrome of inappropriate ADH secretion -As with overhydration, hyponatremia can result in cellular swelling due to movement of water into the cytosol. It can also lead to problems with electrophysiology; specifically, it reduces the sodium ion gradient across the plasma membrane. This can slow depolarization, which slows the rate of action potential generation. Hyponatremia due to overhydration is generally treated with hypertonic saline to restore the plasma sodium ion concentration and draw water back out of the cells.

What can lead to identical twins?

Identical twins are a separate phenomenon that results from the fertilization of a single oocyte by a single sperm, followed by separation of the dividing cells in early development.

What hormone is released if fertilization takes place? What is a major impact of this?

If fertilization does take place, the outer layer of the developing conceptus begins to secrete the LH-like hormone human chorionic gonadotropin (hCG), which keeps the corpus luteum from degenerating and the progesterone level high. hCG is unique to the developing conceptus, which makes it useful as a target compound for home pregnancy tests.

What happens to the corpus luteum if a pregnancy does not occur?

If pregnancy does not occur, the corpus luteum begins to degenerate in approximately 10 days and stops producing hormones.

Which phase of the cycle is less variable?

In these cases, the length of the follicular phase varies, but the luteal phase normally remains constant: It is 14 days from the time of ovulation to the end of the cycle.

Compare and contrast spermatogenesis and oogenesis.

-Both spermatogenesis and oogenesis produce haploid gametes with unique combinations of alleles. -One key distinction is the number of cells produced. -Another difference is in the structure of the gametes.

What is female climacteric? What is menopause?

-The time from the onset of irregular menstrual cycles to their complete cessation, which may be up to 5 years in some women, is called the female climacteric. -menopause: the cessation of regular menstrual cycles that normally occurs between the ages of 45 and 55 years

What assertions have been made by proponents of the alkaline diet? Is there any truth to these assertions?

-Well, according to proponents, we all have blood that is too acidic due to our diets, and acid, they say, causes inflammation, which causes disease. An alkaline diet is therefore the literal cure for every disease, up to and including cancer. As you might expect, these assertions are generally made by people trying to sell you something. -For the first claim, that dietary foods and liquids affect the pH of the blood, remember that the pH of stomach acid is extremely low—about 1-3—and this is true no matter what you eat. Also, remember that the pancreas secretes bicarbonate ions to neutralize the acidic stomach contents entering the duodenum. So, regardless of the alkalinity or acidity of your diet, the food you eat is going to leave your stomach at a pH of about 2, and travel through your small intestine at a pH of about 7. -Proponents do make one true claim, which is that an alkaline environment kills cancer cells. They're right: Cancer cells can't survive in a very alkaline environment, but neither can healthy cells. If the pH is high enough to kill cancer cells, all cells die.

What are the three phases of the uterine cycle? When does each occur (given a 28-day cycle)?

1 Menstrual phase, days 1-5. 2 Proliferative (preovulatory) phase, days 6-14. 3 Secretory (postovulatory) phase, days 15-28

Why is the steep concentration gradient of potassium ions critical to the function of neurons and muscle cells?

-potassium ions are the most abundant intracellular cation The concentration of potassium ions is higher in the cytosol of cells than in any other body fluids due primarily to the actions of the Na+/K+ pump. This steep concentration gradient, like that of sodium ions, is critical to the functioning of neurons and the three types of muscle cells in the body.

Between puberty to menopause, about how many primary oocytes are stimulated to continue development each month?

20-30 primary oocytes are stimulated to continue development

Describe the changing hormone levels during the uterine cycle.

As you can see, at the beginning of the menstrual phase, FSH and LH levels are beginning to rise. Ovarian hormones, however, are at their lowest normal levels until day 5, at which point the growing ovarian follicles start to produce more estrogens. As the proliferative phase begins, the rising levels of estrogens cause a new stratum functionalis to generate and trigger endometrial cells to synthesize progesterone receptors. The high levels of estrogens trigger release of more FSH and LH, and their levels peak around day 14, which causes ovulation. At the start of the secretory phase, the level of progesterone from the corpus luteum begins to rise, while the amount of estrogen secreted decreases. The high progesterone level and falling levels of estrogens inhibit the anterior pituitary, which, as you can see in the graph, leads to low amounts of LH and FSH. This progesterone also stimulates the continuing development of the stratum functionalis during the secretory phase.

Describe the vesicular (tertiary) follicle. Typically, how many follicles become a tertiary follicle each month? What is the name of the fluid-filled cavity?

At puberty, rising levels of FSH and LH stimulate a group of secondary follicles to continue maturation. Usually only one follicle—the dominant follicle—completes this process and becomes a vesicular follicle. As you can see in Figure 26.15, in a vesicular follicle, the smaller pockets of follicular fluid from a secondary follicle merge to form a single large cavity called the antrum. The primary oocyte and its surrounding capsule of granulosa cells, known as cumulus cells, project into the antrum. As the vesicular follicle continues to enlarge, it may reach 15-25 mm (0.6-1.0 in.) in diameter and create a bulge in the surface of the ovary. At this point, the primary oocyte, which has been suspended in prophase I, completes meiosis I to form the secondary oocyte and the first polar body. However, it is then suspended in metaphase II and will not complete meiosis unless fertilization occurs. Keep in mind that the maturation of any one individual oocyte and follicle likely takes 3-4 cycles to complete.

What hormonal changes occur during puberty?

At puberty, the hypothalamus becomes much less sensitive to inhibition by estrogens and progesterone, and the GnRH level increases. GnRH stimulates the HPG axis, and blood estrogens and progesterone levels begin to rise, resulting in the appearance of female secondary sex characteristics.

Describe the stages of oogenesis and when each occurs.

Before birth. The stem cells of females, called oogonia (oh′-oh-GOH-nee-ah; singular, oogonium), undergo their mitotic divisions before birth, during months 2-7 of the fetal period. This means that a female produces all the oogonia she will ever make before she has even been born. At about seven months of fetal development, the total number of oogonia is about 7 million; however, this number drops sharply as many of the oogonia begin to die. The remaining 1-2 million oogonia begin to undergo meiosis I, at which point they are called primary oocytes. The primary oocytes proceed as far as prophase I, after which their development is arrested. Childhood. The primary oocytes remain in prophase I and do not develop further by meiosis until a girl reaches puberty. At that time, rising hormone levels trigger the start of the ovarian cycle. Note that during childhood, primary oocytes continue to degenerate—by the time a girl reaches puberty, the number has dropped to around 300,000. Puberty to Menopause. About once a month after puberty, 20-30 primary oocytes are stimulated to continue development. Usually one primary oocyte (or more in some women) will complete meiosis I to produce two haploid cells that are very different in size. The smaller cell, the first polar body, contains DNA but very little cytoplasm and often degenerates. The larger cell, the secondary oocyte, contains DNA and most of the cytoplasm plus absorbed extracellular fluid. The extra cytoplasm in the secondary oocyte ensures that if it is fertilized, it will have adequate nutrients for its 4- to 7-day journey toward the uterus. The large amount of cytoplasm is also the reason why only the secondary oocyte has the potential to become an ovum.

Describe the primary follicle. What is the shape of the granulosa cells?

During childhood, many of the primordial follicles begin developing into primary follicles. As this occurs, the follicular cells change in shape from flattened to cuboidal, at which point we call them granulosa cells. Two important structures appear in the primary follicles: microvilli and thecal cells. Microvilli develop in the oocyte and grow into the surrounding granulosa cells and form a connection. Part of this connection is a glycoprotein-rich area called the zona pellucida, which becomes important if the oocyte is later fertilized (see Chapter 27). Microvilli also increase the surface area available for the granulosa cells to transfer materials to the growing primary oocyte through gap junctions. Only a small number of the primary follicles will continue development.

What happens during the proliferative phase?

During the proliferative phase, a new stratum functionalis develops with endometrial glands and spiral arteries and veins. As this new layer thickens (proliferates), its endometrial glands enlarge and its spiral arteries and veins increase in number. Cervical mucus is thick and sticky until just before ovulation, when it thins to facilitate the passage of sperm into the uterus. At the end of the proliferative phase around day 14, ovulation occurs.

ConceptBOOST>>> Why does the amount of water in the body affect the sodium ion concentration?

The answer is that it actually doesn't have any effect on the absolute number of sodium ions. Instead, it changes the concentration of sodium ions in body fluids, meaning the percentage of sodium ions relative to water molecules. -The concentration of sodium ions in the body's fluids is determined by both the absolute number of sodium ions in the body fluids and the number of water molecules. So anything that abnormally increases or decreases the number of sodium ions and/or the number of water molecules can cause a sodium ion imbalance. This potential imbalance comes in two forms: hypernatremia, an elevated sodium ion concentration, and hyponatremia, a decreased sodium ion concentration.

What are the two basic ways that the kidneys aid in acid-base balance?

The kidneys work with the lungs in two ways to determine the number of hydrogen ions and base ions in the blood. First, the kidneys can excrete fixed acids that the lungs cannot excrete, such as lactic acid, ketones, phosphoric acid, uric acid, and ammonium ions (NH4+). About 25% of the body's hydrogen ions are eliminated in this manner. Second, the kidneys contribute to acid-base homeostasis by controlling the concentration of bicarbonate ions in the blood. -Generally, the kidneys reabsorb all the bicarbonate ions from the filtrate. Recall, though, that there are no true transport mechanisms to move bicarbonate ions from the filtrate into the tubule cells. For this reason, other, more roundabout methods for reabsorption are needed. In addition, the kidneys can actually manufacture new bicarbonate ions when the pH of the blood falls, and secrete bicarbonate ions when the pH of the blood rises.

What two hormones increase sodium ion retention in the kidneys? How do they work?

The two main hormones that increase sodium ion retention are angiotensin-II and aldosterone -A low extracellular sodium ion concentration is one of the major stimuli that triggers the RAAS. The low sodium ion concentration is detected by receptors in the macula densa of the nephron, which leads to the release of renin and the eventual formation of angiotensin-II. As we've covered, angiotensin-II increases the reabsorption of sodium ions from the proximal tubule. Angiotensin-II also stimulates aldosterone secretion, which causes sodium ion reabsorption from the distal tubule. Note that both actions also indirectly increase water reabsorption, as water follows sodium ions by osmosis.

Describe the secondary follicle.

As childhood continues, the primary follicles develop into secondary follicles. The wall of the follicle thickens, and the deeper granulosa cells secrete follicular fluid, which forms small pockets and increases the overall size of the follicle. In addition, the granulosa cells grow, enlarge, and stimulate nearby cells in the ovary to form a layer of thecal cells around the follicle. Granulosa cells produce estrogens from the secretions of the thecal cells. The primary oocyte is still growing slowly at this stage.

What happens during the secretory phase?

During the secretory phase, the spiral arteries convert the stratum functionalis to secretory mucosa and endometrial glands secrete a nutritious glycogen-rich fluid, also known as uterine milk, into the uterine cavity to sustain the conceptus.

What is first-tier control?

First-tier control. The hypothalamus releases gonadotropin-releasing hormone (GnRH).

The condition respiratory alkalosis is caused by a loss of carbon dioxide through the lungs due to hyperventilation.

Generally, this results from psychological states that increase the rate of breathing. The condition may also occur when an individual is at extremely high altitudes and the low PO2 of the atmosphere triggers hyperventilation.

Metabolic alkalosis results from a loss of hydrogen ions or an excess of bicarbonate ions.

Hydrogen ion loss is commonly the result of prolonged vomiting and the loss of acidic stomach contents. It may also be produced by certain diuretics or excess aldosterone, both of which lead to increased sodium ion reabsorption with concurrent hydrogen ion secretion. An increase in the bicarbonate ion level can happen when excessive bicarbonate salts have been ingested; the "culprit" is usually oral antacids taken for stomach ulcers or severe acid reflux. Compensation for metabolic alkalosis is both respiratory and renal. The respiratory response to a decreased hydrogen ion concentration is hypoventilation. This retains carbon dioxide and increases the number of hydrogen ions in the body. The renal response to metabolic alkalosis is the same as for respiratory alkalosis—the kidneys retain hydrogen ions and secrete bicarbonate ions into the urine.

What are signs/symptoms of hypercalcemia?

Hypercalcemia affects other tissues, as well. Recall that calcium ions are responsible for the plateau phase of the cardiac action potential, which lengthens and strengthens the heart's contraction. When excess calcium ions are present, the plateau phase is shortened, making the contraction shorter and weaker. Hypercalcemia can cause decreased appetite and constipation due to decreased activity of gastrointestinal smooth muscle. It can also cause kidney stones, bone pain, and frequent urination.

What is hypercalcemia? What can cause hypercalcemia?

Hypercalcemia is defined as a plasma calcium ion concentration above 10.5 mg/dl. This condition is usually due to hyperparathyroidism but may also be caused by certain cancers, excess vitamin D, certain bone disorders, and renal failure.

Each type of acid-base disturbance has a characteristic set of ABG findings, which are as follows:

Respiratory acidosis. The primary abnormality seen with respiratory acidosis is an elevated arterial PCO2PCO2 and lower than normal blood pH. If the bicarbonate ion level is elevated, then renal compensation has begun and the acidosis is partially compensated. Metabolic acidosis. The values for metabolic acidosis are slightly more complex, but the general rule of thumb is that you will have a decreased pH and lower bicarbonate ion level in the blood, although this might not always be the case. The PCO2PCO2 is also generally lower than normal because of respiratory compensation. Due to the rapid effects of respiratory compensation, most cases of metabolic acidosis are partially compensated. Respiratory alkalosis. The main findings with respiratory alkalosis are fairly straightforward—an elevated blood pH and a low PCO2PCO2. If the bicarbonate ion level is also low, this signifies partial compensation by the kidneys. Metabolic alkalosis. Metabolic alkalosis shows an elevated blood pH and a high bicarbonate ion level. If respiratory compensation has occurred, the PCO2PCO2 will be elevated.

Normally, the body's buffer systems ensure that the pH of body fluids remains within a narrow range, even when acids or bases are added or lost. But when these buffer systems are overwhelmed by a significant loss or gain of acids or bases, they can fail, resulting in a pH imbalance. The two basic types of pH imbalance are acidosis and alkalosis.

The body attempts to correct both types of imbalances through a process called compensation, which involves respiratory compensation and/or renal compensation.

What is the first phase of the ovarian cycle? When does it occur in a woman's lifetime?

The development of follicles is a process that occurs continuously from childhood to menopause. During the follicular phase, the follicle grows and develops.

Phosphate Buffer System You don't have to memorize the chemical formulas for this buffer system. Know that it consists of a weak acid and a weak base and it a chemical buffer system important in cells and in the filtrate in the kidneys.

The phosphate buffer system consists of the weak acid dihydrogen phosphate (H2PO4−) and its conjugate base, hydrogen phosphate (HPO42−).

How can hyponatremia be treated?

Hyponatremia due to overhydration is generally treated with hypertonic saline to restore the plasma sodium ion concentration and draw water back out of the cells.

What happens to the RMP with mild/moderate hyperkalemia?

Mild hyperkalemia alters the resting membrane potential—the excess of potassium ions in the ECF causes fewer potassium ions to leave the cell through leak channels. This means that the cell retains more positive charges, and as a result the resting membrane potential is more positive at rest than is normally the case

What are signs/symptoms of hypernatremia?

Note that sometimes hypernatremia can be accompanied by overhydration. This occurs when the hypernatremia is due to rapid ingestion of excess table salt or increased secretion of aldosterone, both of which increase water retention by the kidneys. Rehydration will be little help in these cases; for this reason, it's critical for a clinician to determine the primary cause of the hypernatremia so the proper course of treatment can be initiated.

What can cause severe hyperkalemia?

Severe hyperkalemia is almost always due to ingestion or administration of excess potassium ions. This can be intentional, as with a lethal injection, or accidental, as occurs when a medical professional mistakenly gives the wrong dose of potassium salts.

We define the condition respiratory acidosis as a decrease in the pH of body fluids due to excess carbon dioxide.

The carbon dioxide excess happens when ventilation decreases, which is known as hypoventilation (see Chapter 21). Hypoventilation leads to the accumulation of carbon dioxide because less of it is being exhaled. This interferes with the carbonic acid-bicarbonate ion buffer system and causes a shift toward excessive carbonic acid, lowering the pH of the blood. There are three general causes of respiratory acidosis: suppressed ventilation from brainstem dysfunction, blockage of air passages in the lungs, and decreased gas exchange in the alveoli. Whatever the cause, the respiratory and urinary systems attempt to compensate for the acidosis.

Chloride ion regulation is coupled to the regulation of what other ion?

The concentration of chloride ions in the ECF is mostly determined by the kidneys, where the reabsorption of these ions is largely coupled to that of sodium ions. Chloride ions follow sodium ions passively from the filtrate to the ECF due to the electrical gradient created by sodium ion reabsorption. In addition, several transporters move the two ions together.

What is the corpus albicans?

a whitish knot of scar tissue that forms as the corpus luteum degrades -When levels of hormones secreted by the corpus luteum decline, macrophages within the ovary invade the corpus luteum and degrade it while fibroblasts lay down collagen fibers. These actions reduce the corpus luteum to the corpus albicans, a whitish knot of scar tissue (albus = "white"). This event marks the end of one ovarian cycle.

Review: potassium ions are critical in maintaining the ___________ _______________ potential.

resting membrane

What hormones are secreted by the corpus luteum?

secretes progesterone and some estrogens

What are some other effects of female hormones?

- estrogens promotes maturation of sex organs, development of external genitalia, development of breast tissue, preservation of bone mass and maintenance of vascular health. -also helps with maintaining a pregnancy Estrogens and, to a lesser degree, progesterone also stimulate the development of female secondary sex characteristics. These effects include maturation of the sex organs, development of the external genitalia, and maintenance of anatomical features unique to adult females, such as breast development and fat accumulation around the hips and thighs. In addition, progesterone is responsible for maintaining a pregnancy if fertilization occurs Estrogens also have far-reaching effects on other tissues, many of which are beneficial. For example, estrogens reduce the breakdown of bone by inhibiting osteoclasts, which helps to prevent osteoporosis. They also have protective effects on the cardiovascular system—they increase the level of HDLs ("good" cholesterol) in the blood while decreasing the level of LDLs ("bad" cholesterol). However, not all of estrogens' effects on the cardiovascular system are always beneficial, as they promote blood coagulation. This accounts for the increased risk of developing blood clots in women who are taking estrogen-containing medications such as oral contraceptives.

What are the two categories of sources of acids and bases in the body?

Acids and bases in the body come from two main sources: (1) those that are formed as a normal part of metabolic processes, and (2) those that are ingested as a part of the diet.

Why is this more complicated in females than in males?

Another difference is in the structure of the gametes. As you just read, when a secondary oocyte forms, it receives most of the nutrient-rich cytoplasm, and the extra set of DNA is discarded in the polar body. The nutrients in the cytoplasm help support the developing conceptus until it begins obtaining nutrients from the mother. The situation differs for a sperm cell: It only needs to deliver genetic material to the developing oocyte, so excess cytoplasm is removed during spermiogenesis to keep the sperm cell small.

Do the acids and bases we consume in our food have a big impact on pH homeostasis?

Note that although these foods do contribute some amounts of acids and bases to the body, they represent an exceedingly small minority that have essentially no effect on overall pH—the vast majority of acids and bases come from the body's own metabolic reactions, not from outside sources.

What is ovulation?

the process by which the ovary expels a secondary oocyte -In the ovulation phase, generally simply called ovulation, the secondary oocyte and associated granulosa cells, called the corona radiata, are released from the ovary.

Simply put, what happens when the level of calcium ions in the ECF falls? (list 3)

Simply put, when the level of calcium ions in the ECF falls, calcium ions are released from the bone by osteoclasts, more are reabsorbed from the filtrate in the kidneys, and more are absorbed from ingested food and liquids in the small intestine.

What are signs/symptoms of hyponatremia?

Sometimes hyponatremia can exist with dehydration, which occurs with a primary loss of sodium ions and water molecules. This can be caused by prolonged vomiting and/or diarrhea, decreased aldosterone secretion, and diuretic overuse. In such cases, the osmolarity of the ECF is generally nearly isotonic to the cytosol, so isotonic saline is used instead of hypertonic saline.

What are the effects?

The estrogens and inhibin produced have various effects throughout the reproductive system. Estrogens stimulate the dominant follicle to continue developing into a vesicular follicle. The granulosa cells of the new vesicular follicle continue to produce estrogens in increasing amounts. In most cases, a rising concentration of the target hormone would trigger a negative feedback loop; that is, you might expect the rising levels of estrogens to cause the anterior pituitary to decrease LH release. However, the opposite occurs: When the granulosa cells eventually produce enough estrogens, they exert positive feedback on the anterior pituitary, and trigger a large increase in LH release. This increase is known as the LH surge. The LH surge, accompanied by a rise in FSH secretion, triggers ovulation. The resulting corpus luteum produces additional progesterone, estrogens, and inhibin.

What typically happens to the ovulated oocyte?

The fimbriae of the uterine tube sweep the ovarian surface, allowing them to "catch" the ovulated secondary oocyte. The oocyte is then carried into the uterine tube, where a combination of peristalsis and the beating of the cilia moves the oocyte toward the uterus. Nonciliated cells in the uterine tube produce a mucus-like secretion that keeps the oocyte moist and nourished. Note that because the ovary is not directly attached to the uterine tube, the fimbriae may not pick up the oocyte, in which case it is released into the peritoneal cavity. After the oocyte is released, the vesicular follicle collapses and ruptured vessels bleed into the antrum. The remaining structure is known as a ruptured follicle.

What are the first follicles that formed called? What do they contain?

The first follicles formed in the female fetus are called primordial follicles. Each one contains one primary oocyte.

What happens to the remainder of the follicle in the ovary after ovulation?

The luteal phase (LOO-tee-uhl) is the period in which the remnants of the ruptured follicle become an endocrine organ called the corpus luteum.

Acidosis is defined as a body fluid pH of less than 7.35 (note that acidemia refers to low blood pH specifically).

The pH of a patient with acidosis generally remains in the alkaline range (it is rare to see a pH less than 7.0), but it is still more acidic than the normal range. Acidosis develops when more hydrogen ions are added than the body's buffers can bind or when the number of buffers such as bicarbonate ions decreases. This causes neurons to become less excitable, leading to signs and symptoms of nervous system depression, such as slurred speech, drowsiness, and unresponsiveness. Left untreated, acidosis can lead to coma and, in severe cases, death.

Why is there such a steep sodium ion gradient between cytosol and ECF?

The steep sodium ion gradient between the cytosol and ECF also makes this ion critical for all our electrophysiological processes. Recall that cells have a negative resting membrane potential—the inside of the cell is negative compared to the outside. When sodium ion channels open, the sodium ions follow their concentration gradient and rush into the cell. This causes the cell to gain positive charges and depolarize:

What is the stratum functionalis?

The stratum functionalis, or functional layer, undergoes cyclic changes in response to ovarian hormones. It detaches from the uterine wall and is shed as a discharge of roughly 35-50 ml of blood and other materials from the vagina approximately once per month during menstruation.

Metabolic acidosis is defined as the addition of hydrogen ions to the ECF (from acids other than carbon dioxide) or loss of bicarbonate ions.

The term refers to the fact that the condition can result from the addition of metabolic acids such as lactic acid, uric acid, and ketones to the blood. There are many different causes of metabolic acidosis, including prolonged diarrhea (which results in the loss of bicarbonate ions to the feces), the production of excess metabolic acids (such as occurs with diabetic ketoacidosis), failure of the kidneys to reabsorb bicarbonate ions or secrete hydrogen ions, and the ingestion of acidic drugs and toxins such as methanol.

What is the stratum basalis?

The thinner, deeper stratum basalis, or basal layer, does not thicken in response to ovarian hormones, but forms a new stratum functionalis after menstruation ends.

Phosphate ions levels are not regulated tightly. What two hormones regulate calcium and phosphate ion levels? What is the function of these hormones?

The two main hormones involved in calcium and phosphate ion regulation are parathyroid hormone (PTH) and vitamin D3 (calcitriol). -Recall that PTH is released from the parathyroid glands in response to a decrease in the calcium ion concentration of the blood, and it triggers osteoclast activity and calcium ion reabsorption in the kidneys (see Chapter 16). In addition, it decreases the reabsorption of phosphate ions. -Another important effect of PTH is the activation of vitamin D3, which is a potent stimulator of calcium ion absorption by the small intestine. Vitamin D3 also assists PTH in increasing osteoclast activity and calcium ion reabsorption from the kidneys. With regard to phosphate ions, vitamin D3 triggers their absorption from the small intestine. This increases the concentration of phosphate ions in the ECF, in contrast to the effects of PTH, which decreases their level. This helps to ensure that the level of phosphate ions in the ECF does not fall too low.

What occurs during orgasm in females? Do females have a refractory period?

The uterus does exhibit peristaltic waves of contraction, and the cervix pushes down somewhat into the vagina. If semen is present, these actions may draw semen farther into the reproductive tract, but female orgasm is not required for conception. Females do not experience a refractory period, so they may have multiple orgasms during a single sexual experience.

What is third-tier control?

Third-tier control. The ovaries are the target organ of FSH and LH. LH stimulates thecal cells in the follicle to secrete androgens, which diffuse through the basement membrane to the granulosa cells. FSH stimulates granulosa cells in follicles to convert these androgens to estrogens. FSH also stimulates granulosa cells to secrete inhibin.

How many follicles typically develop into a mature follicle each month?

Under the control of this cycle, each month a group of secondary follicles is stimulated to progress to the next stage of development, the vesicular follicle, or tertiary follicle. Again, most of these secondary follicles undergo atresia and die, and usually only one remains.

What happens to the hydrogen and bicarbonate ions that are formed in the reaction above?

When carbonic acid is formed in erythrocytes, much of it dissociates into bicarbonate and hydrogen ions. The hydrogen ions that form bind to hemoglobin, which buffers the cytosol of erythrocytes. The bicarbonate ions, however, are transported into the plasma, where they buffer fixed acids.

What are some signs & symptoms of hypocalcemia?

When hypocalcemia is severe, neurons begin firing spontaneously, leading to repetitive stimulation of skeletal muscles and tetanic (sustained) contractions. For example, the characteristic carpopedal spasm of hypocalcemia

What hormone decreases sodium ion reabsorption?

When secretion of both hormones decreases, the number of sodium ions (as well as the amount of water) reabsorbed decreases. Another hormone that influences sodium ion balance is atrial natriuretic peptide (ANP), which decreases sodium ion (and water) reabsorption. Together, these three hormones maintain a relatively stable plasma sodium ion concentration in the face of sometimes significant swings in sodium ion intake.

Review: 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 🡪 causes depolarization (key event in exciting cells)

Why does your respiratory rate increase when you are exercising and decrease when you are sedentary?

When you are physically active, glycolytic catabolism and oxidative catabolism occur more rapidly and more carbon dioxide is generated. As a result, your respiratory rate increases to match the higher level of carbon dioxide production. The opposite is also true—when you are sedentary, you generate less carbon dioxide and so your respiratory rate decreases.

Why is water balance dependent on sodium balance?

Yet in spite of this significant sodium ion intake, the concentration of sodium ions in the ECF remains stable, thanks to several mechanisms. This is critical not only to sodium ion balance but also to fluid balance, as water reabsorption in the kidneys depends on a gradient consisting largely of sodium ions in the interstitial fluid

What do primary follicles become as they mature?

then to secondary follicles

Which of these are found in a chemical buffer system? How does this minimize pH changes?

consist of a weak acid and its conjugate weak base, function to resist large swings in pH. -When a strong acid is added to a solution, the weak base of the buffer system binds the released hydrogen ions and removes them from solution. When a strong base is added to a solution, the buffer system's weak acid releases its hydrogen ions to bind the base ions. Both situations minimize pH changes and help maintain acid-base homeostasis. The buffering capacity of the body's fluids is known as the alkaline reserve. When the alkaline reserve is depleted, acid-base imbalances can result.

What is the endometrium?

lining of the uterus The endometrium has two main strata, or layers.

Hypokalemia

most commonly caused by diuretics -causes the RMP to hyperpolarize, and so cells are difficult to stimulate

When does the secondary oocyte complete meiosis? *****

only if fertilization occurs

The ovulated oocyte is in which stage of development?

ovulation phase -Stage 5

What is a physiological buffer system? What are the two physiological buffer systems?

physiological systems are functions of organ systems that work to buffer fluids. -the respiratory system and urinary system are the body's physiological buffer systems

List some female secondary sexual characteristics.

the appearance of pubic and axillary hair; an increase in the overall amount of adipose tissue in the subcutaneous layer, with additional deposits in the breasts and around the hips and thighs; increased secretions of sebaceous glands (the oilier skin often results in acne); and skeletal changes, including increased height and widening pelvis.

When do the mitotic divisions take place in females?

undergo their mitotic divisions before birth, during months 2-7 of the fetal period.