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Physiology

Exam 4-Physiology

QuestionAnswer
Reproduction is the method by which organisms make offspring, we get more of an organism.
What are the two basic methods of reproduction in the animal kingdom: asexual reproduction and sexual reproduction.
genes from two individuals are combined in new ways to generate variety in offspring. sexual reproduction,
DNA that comes from your mom gave you your mitochondrial DNA
DNA that comes from your dad is the DNA that determines your genetic sex.
genes from two individuals are combined in new ways to generate variety in offspring. sexual reproduction,
This process of sexual reproduction introduces a lot of variety into these new cells because of these processes: •crossing over during meiosis during the formation of gametes •independent assortment during metaphase I of meiosis •random fertilization
secrete androgens such as testosterone Leydig cells
All embryos have the capability to produce two internal ductwork systems: Mullerian ducts Wolfian ducts
become the female internal anatomy Mullerian ducts
become the male internal anatomy. Wolfian ducts
MIF/MIS causes the Mullerian ducts to regress
testosterone causes the Wolfian ducts to become the epididymis, vas deferens, and seminal vesicles.
In the absences of MIF/MIS, Mullerian ducts persist and become the female internal anatomy
in the absence of testosterone, Wolfian ducts regress.
a system that contains MIF/MIS and testosterone will develop into a male
a system without testosterone will develop into a female.
aids in the development of secondary sexual characteristics such as male body type, thicker skin, deeper voice, and specific pattern of hair growth on the body. testosterone
promotes female secondary sexual characteristics such as body type (wider hips, higher fat percentage, breasts), and thinner skin. Estrogen
the structures that are the precursors of the external genitalia become the penis and scrotum in the presence of androgens such as testosterone
the structures that are the precursors of the external genitalia become the clitoris and labia in the absence of androgens.
become the male internal reproductive structures, persist in the presence of androgens and regress without androgens Wolfian ducts
regress in the presence of MIF/MIS and persist in the absence of MIF/MIS. Mullerian ducts which become the female internal genitalia
The basic pathway for sperm movement out of the male reproductive tract is from the seminiferous tubules
seminiferous tubules, epididymis, testes through vas deferens (ductus deferens) by the seminal vesicle, prostate, and bulbourethral glands into the urethra through the penis and out of the body. pathway for sperm movement
where sperm develop Testes,
located outside the abdominal cavity of the male in the scrotum because the optimal temperature for sperm development is about 3 degrees cooler than body temperature. Testes
Each testicle is about ______and_____with septa that partition the organ into about 250 lobules. 5 cm long 3 cm in diameter
One to four seminiferous tubules are found within each lobule.
large cells that extend from the lumen of the tube out to the periphery. Sertoli cells
The basic job of Sertoli cells is to promote sperm development by acting as a barrier to chemicals that might be in the bloodstream, nourishing sperm, secreting luminal fluid and androgen binding protein, stimulating sperm differentiation and proliferation, secreting inhibin which inhibits FSH secre
Cells on the outside edge of the seminiferous tubules called spermatogonia
are the the diploid (have 46 chromosomes) cells that give rise to sperm. spermatogonia
At puberty some spermatogonia undergo mitosis and differentiation to become primary spermatocytes which are still diploid cells.
For each cell that becomes a primary spermatocyte after mitosis, one cell remains a spermatogonia.
After meiosis I, the cells produced are called secondary spermatocytes
after meiosis II, the cells are called spermatids.
occurs in the ovaries and begins during the first trimester (before birth) during development in human females. Oogenesis
undergo mitosis to produce more oogonia and primary oocytes up until the 20th week of development. oogonia
a female has all the primary oogonia that she will ever have ( ~4 million). By 20th week of development (By birth, this number drops to ~ 1 million as cells are eliminated by apoptosis)
After primary oocytes are formed, they begin meiosis but stop right before the first division (meiosis I) and enter a stage of "meiotic arrest".
lasts until ovulation of that particular egg cell. "Meiotic arrest"
the first meiotic division also occurs which results in a cell ready to undergo meiosis II and a polar body that contains only the extra chromosomes. When ovulation occurs,
The resulting cell will finish meiosis II only if fertilization occurs.
When the sperm binds to the egg, a polar body will be ejected with the excess genetic material.
then the egg will pass out of the body without completing meiosis. If fertilization never occurs,
(males) the hypothalamus releases GnRH which travels to the anterior pituitary gland and triggers the release of FSH and LH.
(males) FSH travels to the Sertoli cells in the testes to trigger ____ (along with testosterone) and trigger the release of _____ spermatogenesis inhibin.
(males) travels to the anterior pituitary to inhibit the release of FSH in a negative feedback loop. Inhibin
(males)travels to the Leydig cells to trigger the release of testosterone which travels to various target tissues to maintain secondary sexual characteristics, promote sex drive, and promote spermatogenesis. LH
(males)travels back to the anterior pituitary to inhibit the release of FSH and LH and back to the hypothalamus to inhibit the release of GnRH in a negative feedback loop. Testosterone
(males)secretion of reproductive hormones in males is controlled by negative feedback loops which result in a fairly constant level of sperm production.
(females) the hypothalamus releases GnRH which travels to the anterior pituitary gland and triggers the release of FSH and LH.
(females) FSH travels to the granulosa cells in the ovaries to trigger the release of inhibin.
(females) Inhibin travels to the anterior pituitary to inhibit the release of FSH in a negative feedback loop.
(females)travels to the theca cells to trigger the release of androgens which get converted to estrogens. LH
(females)In low levels, estrogens travel to the anterior pituitary to inhibit the release of _____ and back to the hypothalamus to inhibit the release of ______ in a negative feedback loop. LH GnRH
(females) promote the development of an egg cell. Estrogens
(females) As the egg cell starts to develop, it starts secreting its own estrogens which means that estrogen levels get higher in the system.
(females)When estrogen levels are high, estrogen triggers the anterior pituitary to start releasing more LH in a positive feedback loop which causes an LH surge in the system.
(females)The LH surge triggers ovulation and the release of the egg.
When the egg is removed from the system, estrogen levels fall to a "low" level again and the system goes back to being under the control of a negative feedback loop.
stay high after the release of the egg from the ovary at ovulation around the 14th or 15th day of the cycle. progesterone levels
The follicle from which the egg came scars over to form the corpus luteum.
For approximately two weeks after ovulation, the corpus luteum continues to secrete progesterone to maintain the endometrial lining of the uterus in case of a possible pregnancy.
If fertilization does not occur, then the corpus luteum slowly decreases its activity until progesterone levels fall enough that they can no longer maintain the endometrial lining.
If fertilization does occur, then the conceptus immediately begins to secrete hCG (human chorionic gonadotropin).
This is the pregnancy hormone detected by home pregnancy tests. hCG (human chorionic gonadotropin).
keeps the corpus luteum active and secreting progesterone until about the 12th to 14th week of pregnancy which maintains the endometrial lining so a normal pregnancy can occur. hCG
When the placenta is developed around the 12th-14th week of pregnancy, the placenta takes over secreting progesterone to maintain the endometrial lining and the corpus luteum fades away.
produced in the seminiferous tubules and moves the epididymis which is about 4-5 meters long for storage. Sperm
When sperm arrive at the epididymis, they are physically and chemically unable to fertilize an egg cell so they must undergo "capacitation" to become motile and mature.
When sperm moves out of the epididymis and into the vas deferens, fluids are added from the seminal vesicles and prostate gland to make semen.
To effectively transfer semen to the female reproductive tract, three events must occur: erection, emission, and ejaculation.
Erection occurs when vasodilation of the arterioles that lead into the spongy tissues of the penis occurs so that more blood flows into the tissues of the penis.
the venous outflow of blood is partially blocked which aids in keeping more blood in the spongy tissues of the penis to maintain an erection.
occurs when semen begins to move into the urethra, Emission
occurs when peristaltic contractions of the tubular system, contractions of the seminal vesicles and prostrate gland, and contractions of the muscles at the base of the penis occur to force the semen out the tip of the urethra. ejaculation
under parasympathetic control and emission and ejaculation are under sympathetic control. Erection
The volume of semen in a single ejaculation is from 1.5 to 5.0 ml.
The normal range for numbers of sperm cells in each milliliter of semen is 40 million to 250 million.
By the time the sperm reach the uterine tubes, only about 100 have survived to enter each uterine tube.
If a secondary oocyte is present in the tube, the sperm cells will surround it and start tunneling through the corona radiata and the zona pellucida surrounding the egg using their digestive enzymes in their acrosomes.
When the first sperm cell reaches the egg and binds to the surface, chemical changes occur in the zona pellucida that keep other sperm from entering.
the secondary oocyte finishes meiosis and ejects the polar body. When fertilization occurs,
The chromosomes from the egg and sperm join and development begins.
Secondary oocytes can only live from ____but sperm cells can live from ______ within the female body. 4-24 hours after ovulation, 3-7 days
As the fertilized egg (zygote) travels down the uterine tube towards the uterus, cleavage (division by mitosis) begins to form an embryo.
The embryo usually arrives at the uterus within 4 days of fertilization.
The embryo does not usually implant on the uterine wall for another 2 days.
By the time implantation occurs, the embryo has been converted into a blastocyst with an inner mass of cells which will become the fetus and an outer layer of cells which will become the placenta.
When the fetus has developed into a size that starts to stretch the uterine walls in such a way as to resemble a muscle contraction, labor begins.
Labor occurs because of a positive feedback loop that occurs when stretches on the uterus cause a signal to be sent to the hypothalamus that triggers a signal to be sent to the posterior pituitary to release oxytocin.
travels to the uterus and amplifies contractions which send a signal that causes even more to be released. Oxytocin
released from the uterus which also aid in muscle contraction. prostaglandins
will occur until partuition or birth of the baby occurs. This positive feedback loop
composed of lobes that are subdivided into lobules which contain glandular alveoli that secrete milk. The mammary glands
converge into larger and larger ducts that eventually lead to the nipple from which milk is released. alveoli
estrogen levels in the system fall which decreases the amount of prolactin inhibiting hormone (PIH) secreted by the hypothalamus. This allows prolactin secretion from the anterior pituitary to increase milk production. At partuition
fall with the removal of the placenta which decreases the inhibition of milk secretion. estrogen and progesterone levels
uses chemicals called hormones to send signals endocrine system
are secreted by endocrine glands which are ductless glands that secrete substances directly into the space between cells where they can diffuse directly into the bloodstream and be carried to any part of the body. Hormones
Control of hormone concentration in the blood can be attained in two ways. Stimulation or inhibition
Hormones are usually regulated by negative feedback loops
allow several places where amount of hormone produced or released can be affected. This mechanism allows for very precise control of the amount of hormone in the bloodstream at any given time. "long-loop" negative feedback loops.
The first pattern of hormone release in the human body is a simple negative feedback loop where changes in the plasma concentration of a particular organic molecule or mineral ion can affect the amount of hormone released from a gland.
The second pattern of hormone release in the human body occurs when a neurotransmitter or hormone from a neuron makes contact with an endocrine cell.
located just above the pituitary gland in the brain. hypothalamus
connected to the anterior pituitary gland (adenohypophysis) by a capillary bed and to the posterior pituitary gland (neurohypophysis) by the axons of neurons. hypothalamus
What Happens to the Hormone after It is Released? •It can bind to a receptor and cause an action at its target tissue. •It can be excreted in the urine. •It can be broken down by enzymes in the blood or on a target tissue (inactivated by metabolism).
are small proteins constitute the majority of hormones. Peptide hormones
The molecule is called a hormone if it is released from an endocrine gland.
The first type of amines are the catecholamines which include epinephrine, norepinephrine, and dopamine.
Amines are released from actual or modified neural tissue such as the adrenal glands and often play important roles in behavior and stress responses.
The second type of amines are the thyroid hormones which contain iodine and affect almost every cell in the body via effects on metabolism.
lipophilic molecules containing four carbon rings. steroid hormones
For a hormone to have any effect on a cell, that cell must have an active receptor for that hormone.
When a hormone binds to that receptor the signal gets transduced from a chemical signal (the hormone) to a change in protein activity in the cell.
Intracellular receptors are on the inside of cells in the cytoplasm.
hormone must be able to diffuse through the plasma membrane of the cell to bind with an intracellular receptor.
Both steroid and thyroid hormones can diffuse through the membrane and bind to intracellular receptors.
When the hormone binds to the receptor and forms a hormone-receptor complex, the hormone-receptor complex diffuses through the nuclear membrane and binds to the DNA to initiate or inhibit gene transcription.
Membrane bound receptors are found on the surface of the cell.
Peptide hormones, catecholamines, and sometimes steroid hormones can bind to membrane-bound receptors.
what happens to the internal reproductive system in the presence of testosterone and MIS only Wolffian ducts persist
When does a developing egg undergo the first dividion of meiosis at ovulation
Egss are produced cyclically and sperm are produced continuously True
When does a developing egg undergo the second division of meiosis at fertilization
Which cells in the male system secrete testosterone leydig cells
what is the role of progresterone during the second half of the female menstrual cycle to maintain uterine lining
The sex chromosomes of females are XX
a surge of which hormone triggers ovulaiton LH
In the absence of MIS, what happens to Mullerian ducts turn into uterus and uterine tubes
where does fertilization typically occur uterine tube
Created by: klmd3014