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Biology
Reproduction & Development
| Question | Answer | Ans pt.2 |
|---|---|---|
| During the endocrinology of reproduction a hormone is released, what is it, where is it released from, and what does it do? | - Gonadotropin releasing hormone (GnRH) - Released from the hypothalamus - It signals the anterior pituitary to release the gonadotropins luteinizing hormone (LH) & follicle stimulating hormone (FSH) - LH & FSH both travel to the glands | |
| What are considered the gonads in both males & females? | - Males = testes - Females = ovaries | |
| What are the two general responses that gonadotropins elicits? | 1) production of steroid hormones 2) production of germ cells - Male = spermazoa - Females = ova | |
| Where are spermatogenic cells found? | They are found within the seminiferous tubules. These tubules are found within each testis | |
| What are leydig cells? | - They are specialized interstitial cells that lie outside the seminiferous tubules | |
| Where is testosterone synthesized? | Within leydig cells | |
| What are Sertoli cells? | These cells act to promote spermatogenesis and they also produce the protein hormone inhibin | |
| True or False: Sertoli cells are in direct contact with spermatogenic cells | True | |
| Define spermatogonia | They are spermatogenic cells that are closer to the basement membrane of the seminiferous tubules which separate the Sertoli cells from the interstitial cells | |
| How many chromosomes do spermatogonia have? | 46 | |
| Define primary spermatocytes | It is spermatogonia that undergo mitosis by the basement membrane | |
| What are the names of the 1st & 2nd meiotic division is sperm production? | - 1st = secondary spermatocytes - 2nd = spermatids | |
| By the end of the 2nd meiosis, how many chromosomes are present? | 23 | |
| Explain what the transformation event is in sperm production | When spermatids are initially formed, they are all connected to each other by cytoplasmic bridges. During this event the spermatids essentially bud out to form spermatozoa | |
| What is on the top of a spermatozoa & what does it do? | - On the tip of a spermatozoa is a structure called acrosome which contains a lot of digestive enzymes - These digestive enzymes help the spermatozoa gain access to the interior of the egg once fertilization has taken place | |
| What can be found inside the head of the spermatozoa? | There is a nucleus which contains DNA. In the midsection are mitochondria, providing energy for the whipping movements of the tail | |
| In sperm production, how is DNA able to synthesize RAN? | Leydig cells convert cholesterol -> testosterone (diffuses into Sertoli cells) ->-> dihydrotestosterone (dHT) (diffuses into nucleus) ->->-> DNA synthesizes RNA | |
| What does the binding of LH do in sperm production? | - LH binds to specific receptors on the membrane of leydig cells - It increases the production of cholesterol to testosterone | |
| What does the binding of FSH do in sperm production? | -FSH binds to surface receptors in the Sertoli cells - Helps with conversion of testosterone to dihydrotestosterone (dHT) | |
| What does inhibin do? | It acts as a negative modulator of the anterior pituitary | |
| What happens to sperm when it is filly developed? | It leaves the seminiferous tubules & enters the epididymis & the vas deferens where it will stay there for 14 days | |
| What happens after the 14 days are up for the sperms? | They are ejected out down the vas deferens & into the ejaculatory duct due to the contraction of the smooth muscle lining the walls | |
| Besides the sperm, what makes up semen? | Fluids from the seminal vesicles, prostate gland, & bulbourethral gland | |
| What happens from the time the sperm is ejaculated into the fertilization site? | - Once the sperm is ejaculated into the vagina they only have 48 hours to live - ~ 30 min after ejaculation, the sperm reaches the site if fertilization, the fallopian tubes (oviduct) | |
| What happens to the sperm from after fertilization to delivery of the baby? | - Fertilized egg moves down the oviduct to the uterus where it implants in the uterine lining - A week of fertilization, the egg is now called a blastocyst & it implants in the lining of the uterus where it will grow up until delivery date (parturition) | |
| Define oogenesis | It is the production of the female germ cell | |
| Explain what primary oocytes are | - They are what the cells are called after going through mitosis - This division occurs w/in the first two or three months of fetal development - Will have 46 chromosomes - At birth females will have ~ 400,000 primary oocytes in both ovaries | |
| Define atresia | It is the process at which the remaining primary oocytes will be degenerated at various stages during the development process | |
| What are secondary oocytes? | - They are what cells are called after going through the 1st meiotic stage division - It has 23 chromosomes | |
| Explain what a first polar body is | - During the 1st meiotic division one of the two daughter cells obtains all the cytoplasm (secondary oocytes) while the other cell is just a small sphere of DNA (1st polar body) - They still divide to give two polar bodies | |
| When does the 2nd meiotic division occur in females? | It only occurs when a secondary oocyte becomes fertilized | |
| How many chromosomes does the ovum contain before and after fertilization? | - Before = 23 chromosomes (female only) - After = 46 chromosomes (23 male & 23 female) | |
| What are primary follicles? | - It is actually primary oocytes surrounded by a large layer of follicle cells - Usually only one is formed, unless you have fraternal twins, you would have two follicles developing at the same time | |
| What is the follicular phase? | - It is a period of time in which the primary oocyte is maturing with the aid of estrogen, LH, & FSH - Process takes up to ~ 2 weeks | |
| Define zona pellucida | It is a membrane that surrounds the primary oocyte | |
| Define granulosa cells | - It is a type of follicle cell that surrounds the zona pellucida - Analogous to Sertoli cells in males | |
| Define theca cells | - It surrounds the granulosa cell - Analogous to the leydig cells in males | |
| Define antrum | - It is a fluid that starts to build up within the primary follicle - After it has been formed the follicle is ready for ovulation | |
| What occurs when ovulation begins? | - The hormone LH surges & the primary oocyte undergo 1st meiotic division forming a polar body & 2nd oocyte - LH also causes the production of enzymes. They breakdown the membrane of the follicle - Once the 2nd oocyte is released, ovulation starts | - The leftover follicles is transformed to the corpus luteum |
| What is the main function of the corpus luteum? | It is to produce estrogen and progesterone | |
| What is the luteal phase? | - It starts when ovulation begins - If there is no pregnancy then it ends when you menstrual cycle starts - This phase takes about 2 weeks | |
| What occurs when there is a low concentration of estrogen? | There is a negative feedback on FSH production | |
| What happens when there is a high concentration of estrogen? | Estrogen has a positive feedback on the anterior pituitary & LH production | |
| What does the corpus leteum become? | It becomes an endocrine gland that will synthesize estrogen & progesterone | |
| Estrogen and progesterone combined has a negative feedback on LH & FSH production. What is the result of this feedback? | - The primary follicle is prevented from developing - As long as the corpus luteum is producing estrogen & progesterone, the primary follicle is unable to develop | |
| What is a zygote? | - It is when the nucleus of the sperm & the nucleus of the egg fuse together - It has 46 chromosomes | |
| What happens when a zygote begins to form? | It rapidly develops and in about 7 days attaches itself to the uterine lining as a blastocyst | |
| Define blastocyst | - It is essentially a small ball of cells with a central fluid- filled cavity - Once an embryo enters the uterus it is called a blastocyst | |
| What is the placenta made up of and when does it form? | - It is made up of material and fetal cell types - It starts to form implantation takes place | |
| What does the placenta synthesize? | - Chorionic gonadotropin (CG): positive feedback to the corpus luteum - Chorionic somatomammotropin (CS): positive feedback to the mammary gland | |
| What are the different hormones that has a positive feedback on the mammary gland? | - Prolactin: from the anterior pituitary - Estrogen & progesterone: from the corpus luteum - Chorionic somatomammotropin: from the placenta | |
| What is no longer produced in the last 6 months of pregnancy & why? | - GC is no longer produced b/c the corpus luteum breaks down & it no longer produces estrogen & progesterone - The placenta takes over the estrogen & progesterone production for the last 6 months | |
| How is the coelom divided & what is a part of each division? | - Thoracic cavity: contains the heart and lungs - Abdominal cavity: consists of organs like the stomach & the intestinal system | |
| What do cells of similar types do? | They form tissues and then tissues come together to form organs | |
| What are the stages that characterize development? | 1) Fertilization: zygote formation 2) Cleavage: zygote cleaved into smaller cells 3) Gastrulation: formation of 3 primary germ layers ( ectoderm, mesoderm, & endoderm) 4) Neurulation: nervous system formation | 5) Neural Crest Formation: parts of nervous system, skull, & sensory organs form 6) Organogenesis: all other organs form 1) Fred 2) Can’t 3) Get 4) Nora’s 5) Number 6) Obviously |
| What will the ectoderm end developing into? | The skin, lens of the eye, the brain, & the nervous system | |
| What will the mesoderm end up developing into? | Notochord, heart, skeleton, muscle, the outer coverings of internal organs, & the reproductive organs | |
| What is the embryo referred to in the gastrulation phase of development? | Gastrula | |
| What will the endoderm end up developing into? | Inner longing of digestive tract, the respiratory tract, & major glands of the body like the liver & pancreas | |
| What is direct/ indirect development? | - Direct: being taken care of after birth (ex: humans) - Indirect: parents leaving you after birth & you have to fend for yourself (ex: frogs/ tadpoles) | |
| Define trophoblast | - It is cells that form the outer layer of the blastocysts - Once the embryo implants into the uterus the trophoblastic cells will grow into the lining of the uterus | |
| Define chorion | - It is a layer of cells between the trophoblast and the fetal blood - Chorion preserves the barrier between the mother’s & fetal’s blood | |
| What is the amniotic cavity? | It is a fluid- filled sac that surrounds the embryo & fetus, f is filled with amniotic fluid | |
| What must be done so the uterine lining is maintained? | The trophoblastic cells secrete CG which causes the corpus luteum to release estrogen and progesterone | |
| What role does oxytocin play in giving birth? | - When contractions start nerve impulses are sent to the hypothalamus which then send signals to the posterior pituitary to release oxytocin - Oxytocin is released into the blood & is a string induced of more | - Oxytocin stimulates the production/ secretion of prostaglandins which also increase contractions % |
| Explain milk production | 1) child sucks nipples 2j impulses sent to hypothalamus 3) release of PRH (prolactin releasing hormone) which acts on anterior pituitary 4) PRH stimulates anterior pituitary to release prolactin into blood stream | 5) Prolactin in blood stream stimulates epithelial cells in breast to produce milk |
| Explain milk ejection | 1) child sucks nipples 2) breast send signals to hypothalamus 3) hypothalamus sends signals to posterior pituitary 4) posterior pituitary releases oxytocin 5) oxytocin causes contraction of myoepithelial cells in the breast 6) milk comes out | |
| What is the chromosome count at the start and end of mitosis? | Start= A single 46 diploid cell End= Two 46 diploid cells | |
| What is the chromosome count at the start and end of the first meiosis? | Start= A single 46 diploid cell End= Two 23 daughter cells | |
| What is the chromosome count at the start and end of the second meiosis? | Start= Two 23 daughter cells End= Four 23 haploid cells | |
| What is the vegetal pole? | It is the lower hemisphere of the unfertilized egg | |
| What is the purpose of the vegetal pole? | There is a large amount of yolk in this pole, and it acts as food for the developing embryo | |
| What is the animal pole? | It is the upper hemisphere of the unfertilized egg, which mainly contains cytoplasm | |
| What is the grey crescent? | It forms on the dorsal portion (future back) of the animal | |
| What do you eventually find in the place of the grey crescent? | The spinal cord and brain | |
| What forms in the ventricle side of the grey crescent? | The belly of the organisms | |
| Define meridian | It is an imaginary line which connects the two poles | |
| What happens when a zygote is already formed? | It undergoes a special cell division to increase its mass but not its overall size | |
| Explain attachment theory | It describes a series of steps that infants will progress through as they grow. During the first three months of life, an infant will indiscriminately attach to any person and will respond equally to any caregiver |
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Gabbgabb04
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