Stupid Biology

How long do you think it takes after intercourse for sperm to reach the oocyte?

6-12 days, if it takes any longer, its likely to not be a pregnancy

What is progesterone?

A hormone that helps maintain the uterine lining during pregnancy.

What makes them hormones?

A receptor that signal and travels through the blood stream

Posterior pituitary

An extension of the hypothalamus composed of nervous tissue that secretes hormones made in the hypothalamus; a temporary storage site for hypothalamic hormones

Why do sperm have digestive enzymes in the acrosome?

Because they need to break down the cell wall.

Humans are diploid organisms that have 46 chromosomes and produce some haploid cells. What does diploid mean? What does haploid mean? What does haploid cells do humans produce?

Diploid refers to a pair of homologous chromosomes, one set inherited by each parent. It is in an organism that reproduces sexually. Haploid is in the life cycle of an organism that reproduces sexually, and is a cell containing a single set of chromosomes.

What would the receptor for LH do?

Found in testes and ovaries, also in uterus and breasts. It makes sure that the LH cells that the signal is received by the cell.

Do you think the defective LHR could be the explanation for the symptoms? explain.

If LHR is not detected by the testes then theres no androgens. Without that nothing will develop or form. Absence of the receptor makes more LH and that causes a negative feedback. If LHR is not detected ovulation and corpus luteum will not happen. YEs, things will work okay there would just be no ovulation. It could be the explanation, but there could also not be any LH.

Independent vs. dependent

Independent: Day of implantation Dependent: % of early loss

What is the importance of hormone receptors?

Reception of the signal occurs when a hormone binds to a specific receptor protein on or in the target cell. The result is a response, a change in the cells behavior. Cells that lack receptors for the particular chemical signal do not respond to the signal.

Compare the production of sperm to the production of oocytes. How are they the same/different?

Sperm is a male gamete. Oocytes is a cell in an ovary that may undergo meiotic division to form an ovum. The male gamete, the sperm, is a relatively small cell that moves by the means of a flagellum. The female gamete, the egg, is a much larger cell that is not self-propelled.

What is corpus lutuem? Does it produce anything? What?

The Corpus lutuem is a solid mass of follicular tissue that had been surrounding the egg that was just ejected within the ovary. What do it produce? It secretes additional estrogen as well as progesterone. Helps maintain uterine lining during pregnancy.

What is a notochord? When is it formed? What tissue layers is it formed from?

The notochord extends for the most of the embryo's length and provides support for other developing tissues. Later in development, the notochord will function as a core around which mesodermal cells gather and form the backbone.

What are the polar bodies?

There are two, the first and second polar body. First occurs with the completion of meiosis I and onset of Meiosis II. It receives almost no cytoplasm. The Second polar body occurs after the entry of sperm triggers completion of meiosis II. It recieves virtually no cytoplasm, and quickly degenerates, leaving the mature egg with nearly all the cytoplasm, and thus the bulk of the nutrients contained in the original diploid cell.

What other hormonal defect(s) might cause genetically male child to develop as a female?

Too much estrogen, not enough LH or LHR

What role does LH play in men and women?

Women: stimulates the completion of meiosis I, transforming the primary oocyte in the follicle into a secondary oocyte. It also signals enzymes to rupture the follicle, allowing ovulation to occur, and triggers the development of the corpus luteum from the ruptured follicle. Also promotes the secretion of progesterone and estrogen by the corpus luteum. Men: promotes the secretion of androgens, mainly to testosterone.

What is a luteinizing hormone?

a hormone secreted by the anterior pituitary gland that stimulates ovulation in females and the synthesis of androgen in males. Stimulates growth of ovarian follicle and production of secondary oocyte. Protein Stimulates the secretion of other hormones. Male: Hypothalamus- Anterior pituitary- LH- Testes(LHR protein)- Androgens(testosterone) Female: Hypothalamus-Releasing hormone- Anterior pituitary-(FHS-ovaries-follicle development- egg oocyte-corpus luteum)- LH- LHR- Ovaries- Ovulation + formation of corpus luteum- Progesterone- Uterus

Anterior pituitary

composed of endocrine cells that synthesize and secrete numerous hormones directly into the blood.

Try to explain how a nerve impulse is transmitted from one nerve cell to the next and then propagated through the receiving nerve cell.

first thing that happens is the sending nerve cell sends neurotransmitters and those neurotransmitters gets sent to the synapse. The synapses transmit signals b/w nerve cells. In order for that to be received has to be connected by a receptor. These receptors are called Ion channels (they are lingingated ion channels, they open and close, something binds to it). Potassium, sodium, calcium: positive charge (Interior nerve cell). Neurotransmitters activate ion channels on neighboring nerves.

What is a hormone?

hormones send messages that link the two cycles, synchronizing follicles growth in the ovaries with the establishment of a uterine lining that can support a growing embryo.

FSH

Stimulates the ovaries for the follicle development. This is what the egg develops in. Creates the corpus luteum.

What is the uterus?

The womb and actual site of pregnancy.

What does oxytocin do?

(Posterior lobe, peptide) Stimulates contraction of uterus during labor and ejection of milk from mammary glands. Regulated by the nervous system.

What are diabetes mellitus? How do the two types of diabetes mellitus differ?

A human hormonal disease in which body cells cannot absorb enough glucose from the blood and become energy starved; body fats and proteins are then consumed as energy. Type 1 (insulin-dependent) diabetes results when the pancreas does not produce insulin. Type 2 (non-insulin-dependent) diabetes results when body cells fail to respond to insulin

What does Anti-diuretic Hormone (ADH) do? What affect does alcohol consumption have on the production of ADH?

A relatively small (peptide) molecule that is released by the pituitary gland at the base of the brain after being made nearby (in the hypothalamus). ADH has an antidiuretic action that prevents the production of dilute urine (and so is antidiuretic).

What are gastrulation and neurulation?

Gastrulation: the second major phase of embryonic development, which transforms the blastula into a gastrula. Gastrulation adds more cells to the embryo and sorts the cells into district layers. Neurulation: Formation of the nerve plate and nerve tube, happens after gastrulation. Cleavage-blastula-gastrulation-gastrula-neurulation Embryonic Layers: Ectoderm-Endoderm-Mesoderm

How does the structure of the placenta contribute to its function?

In most mammals, the organ that provides nutrients and oxygen to the embryo and helps dispose of its metabolic waste; formed of the embryo chorion and the mother's endometrial blood vessels.

How are gastrulation and neurulation similar? Different?

They are similar b/c they both entail the growth of cells into structures necessary for the creation of an organism. Gastrulation on one hand, comes first and creates a 3 layer structure (ectoderm, endoderm, mesoderm). Where as neurulation comes after and is the start of the growth of certain parts of the organism itself (such the nerve plate and nerve tube). This will then turn into the backbone that will replace the notochord.

What is negative feedback? describe the process by which negative feedback regulates a) calcium concentration in the blood and b) glucose concentration in the blood.

Negative feedback is a primary mechanism of homeostasis, whereby a change in physiological variable tigers a response that counteracts the initial change. Negative feedback is a common control mechanism in which a chemical reaction, metabolic pathway, or hormone-secreting gland is inhibited by the products of the reaction, pathway, or gland. As a concentration of the products builds up, the product molecules themselves inhibit the process that produced them. a)The parathyroid gland releases the parathyroid hormone when blood levels of ionic calcium decline. It stimulates osteoclasts, the bone breakers, to destroy bone matrix, releasing calcium into the bloodstream. When calcium concentration in the blood rises to normal levels, the stimulus for parathyroid hormone release ends. When blood calcium levels rise, calcitonin is released by the thyroid gland. Calcitonin stimulates calcium deposits in bone and inhibits osteoclasts from breaking down bone. Osteoblasts are stimulated to make more bone tissue. As these things happen blood calcium levels reduce to normal and the stimulus ends. b) Glucose regulation in the body is a process of keeping the body in homeostasis. The two important hormones for blood glucose regulation are insulin and glucagon. When we break down the foods we eat, our blood pressure increases due to carbohydrates.When levels increase, the beta cells secrete insulin which then converts glucose to glycogen so that extra glucose can be stored restoring glucose levels to a normal level. When levels fall, the alpha cells secrete glucagon which converts stored glycogen to glucose increasing levels back to normal.

What is meiosis and what does it have to do with reproduction?

Reproductive cell regeneration. It goes from a diploid cell to a mature egg. The process where we go from diploid to haploid. 46 chromosomes- 23 pair. Meiosis I and Meiosis II goes from 1 diploid to 4 haploid. 1 oocyte and 2 polar bodies - females 4 sperm - males Meiosis II occurs during fertilization.

What are Androgens?

The LH hormone promotes the secretion of Androgens which stimulate sperm production. Androgens carried in the blood help promote homeostasis.