BIOS 1710: Biological Sciences II, Week 7 Notes
BIOS 1710: Biological Sciences II, Week 7 Notes BIOS1710
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This 7 page Class Notes was uploaded by Sydney Jones on Friday October 7, 2016. The Class Notes belongs to BIOS1710 at Ohio University taught by Scott Moody in Fall 2017. Since its upload, it has received 8 views. For similar materials see Biological Sciences II: Ecology, Evolution, Animal Body Systems in Biology at Ohio University.
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Date Created: 10/07/16
Week 7 October 3-7 CH 38 Endocrine System- regulates an animal’s internal functions • Works closely with the NS • Relies on cells and glands that secrete hormones • Move by the blood stream • Generally slower than NS signals • Have long-term effects - Fungi are one of the most abundant and diverse groups of eukaryotic organisms; largely responsible for decomposition of plant and animal Growth and Development - Hormones help in the molting and metamorphosis process ** Know this! - Growth hormone is produced in the pituitary gland (located under the brain) Homeostasis - Hormones regulated the internal homeostasis of an organism Negative Feedback- homeostasis depends on this; change in a system causes a response to bring it back to the baseline Positive Feedback- accelerates the response of the target cells; causes a response in the same direction; labor contractions Diabetes Mellitus- when control of glucose levels from insulin fail; untreated leased to excess glucoses in the urine and cardiovascular and neurological problems Properties of Hormones 3 main classes: 1. Peptide 2. Amine 3. Steroid Peptide Hormones - Derived from amino acids - Short chains - Can evolve - Abundant - Hydrophilic (can not pass through the membrane) - Alter the biochemical activity of the cell by activating/inactivating enzymes - Can change gene expression - Minutes to hours Amine Hormones - Derived from amino acids - A single aromatic amino acid - Abundant - Hydrophilic (can not pass through the membrane) - Alter the biochemical activity of the cell by activating/inactivating enzymes - Can change gene expression - Minutes to hours Steroid - Derived from cholesterol - Evolutionary changes depend in the receptors - Hydrophobic - Form a steroid hormone-receptor complex and are transported into the nucleus (transcription factors) and stimulate gene expression - Days to months Releasing Factors- initially released by the hypothalamus; starts the hypothalamic- pituitary axis Vertebrates - The pituitary gland is the most important Hypothalamus- main rout which NS signals are transmitted to the ES; transmits directly to the pituitary gland Anterior pituitary gland- formed of epithelial cells Posterior pituitary gland- formed of neural tissue - The hypothalamus contains neurosecretory cells that release “releasing factors” to the APG that in response release hormones into the blood - The PPG has axons of neurosecretoy cells and release hormones directly into the blood Anterior Pituitary Gland Posterior Pituitary Gland Thyroid stim hormone- thyroid gland Oxytocin Gonadotropic/luteninizing- f/m gonads Antidiuretic(vasopressin) Adrenocorticotropic- adrenal glands Tropic Hormones- hormones that control the release of other hormones Thyroid Gland- located in the front of the neck - Thyroid hormones require iodine for production so those who do not have enough iodine have metabolic problems and can cause the gland to swell - Ovary and testis respond to FSH and LH to control development and sexual differentiation **Testosterone is a naturally occurring anabolic steroid Adrenal Glands- paired; adjacent to the kidneys Parathyroid Gland- respond to internal state of the body; secretes parathyroid hormone (PTH); controls bones formations/removal and levels of calcium in the blood Pineal Gland- located in the thalamic region of the brain; responds to the autonomic NS; secretes melatonin ▯ hibernation in some animals Adrenal Medulla- the inner part of the adrenal gland; sympathetic NS has axons here; secretes epinephrine and norepinephrine ▯ flight or fight response CH 48 Asexual Reproduction - When organisms reproduce from asexual reproduction they produce identical cells (clones) - Eukaryotic cells divide by mitosis Types of asexual reproduction: 1. Binary Fission- cell division 2. Budding- when a but forms on an organism and brakes off 3. Fragmentation- when a organism is split into pieces and each piece develops into a whole organism 4. Parthenogenesis- “virgin birth”, when females produce eggs that do not need to fertilized by males, can have all females at once or all males but not mixed Pros: • No need to find a mate (time and energy) • Rapid and allows exponential population growth ▯ Twofold cost of Sex • Genetically identical Cons: • Can not adapt quickly to environmental changes • Fds - There are very few ancient asexual groups Sexual Reproduction - Uses two complete sets of genes (from 2 organisms) to make genetically unique offspring Meiosis- form of cell division that halves the number of chromosomes; chromosome duplication and two rounds of cell division; results in 4 cells with half the genes from the parent Gametes- the cells that are produced from meiosis - Female have ova (eggs) and males have spermatozoa (sperm) and they differ in shape and size Zygote- fusion of two gametes (one from each parent) Embryo- early stage of multicellular development, division by mitosis Organisms that Use Both - Most that can reproduce asexually can also reproduce sexually Male Reproductive System - Sperm is produced in the testes - Males produce a lot of sperm because only about 200 will make it to the egg for fertilization - Sperm are haploid cells Parts of Sperm: 1. Head- densely packed nucleus with chromosomes; enzymes to penetrate the barrier around the egg (called the acrosome) 2. Midpart- supplies ATP to the tail 3. Tail- moves the sperm Scrotum- where the testes are located outside the abdominal cavity - Not all mammals have a scrotum - Sperm production requires a lower tem than body tem Seminiferous Tubules- where sperm is produced by meiosis Epididymis- where sperm is stored to mature Vas Deferens- long muscular tube, starts in scrotum and connects with the ejaculatory duct - The urethra is used by both urinary and reproductive systems in males - Sperm is only 5% of semen Glands: 1. Prostate gland- 30%, slightly alkaline fluid for motility and counteracts the acidity of the female reproductive tract 2. Seminal vesicles- 2, 60%, secretes protein and sugar to provide energy 3. Bulbourethral glands- for lubrication in the urethra - The urethra is enclosed in the penis - Arteries become dilated and veins compress causing an erection - Rhythmic contractions of the vas deferens pushes the sperm through the reproductive system Female Reproductive System Oocytes- developing female gametes, mature into ovaries, largest cell by volume in the human body - When released the oocyte goes through the fallopian tube (oviduct) and into the uterus - There is a fallopian tube on each side - The end of the uturas is called the cervix and enters into the vagina Vulva- external female genitalia, labia majora and labia minora (for protective covering) - The clitoris is the female homolog of the glans penis Hormone Regulation - Hypothalamus secretes gonadotropin-releasing hormone (GnRH) - GnRH simulates the APG to secrete LH and FSH, acting on both male (continually) and female (cyclically) - From this testosterone, estrogen and progesterone is secreted Males - LH acts on Leydig cells to secret testosterone - Regulates growth, development, reproduction - Increase in testosterone leads to secondary sexual characterizes (deep voice, facial, body, and pubic hair, and increased muscle mass) Sertoli Cells- works with FSH and testosterone to stimulated sperm production Females - FSH acts on follicle cells (surrounds the oocyte) to support the oocyte and secretes estrogen - When estrogen levels increase it leads to secondary sexual characteristics (emerged breast, growth of body and pubic hair) - At puberty females begin a menstrual cycle Menstrual Cycle - Regulated by hormones - About 32 days Two stages: 1. Follicular Phase 2. Luteal Phase Follicular Phase (about 14 days) - FSH acts on granulosa cells (subset of follicle cells) to mature oocytes - Granulosa cells also secrets estrogen to thicken the lining of the uterus * preparing it for pregnancy - LH continues to rise because of the estrogen creating a surge leading to ovulation (beginning of luteal phase) Luteal Phase (about 14 days) Corpus Luteum- follicle cells with out oocyte, secretes progesterone (thickens the uterine lining) If the oocyte is fertilized: - It implants into the uterine lining (about 1 week after fertilization) - The embryo secrets human chorionic gonadotropin (hCG) to keep the corpus luteum maintaining progesterone until the placenta can take over **hCG is the hormone tested in pregnancy tests - High levels of the estrogen and progesterone block ovulation because it inhibits GnRH, GSH, and LH If it is not fertilized: - The corpus luteum degenerates - Estrogen and progesterone levels drop - This causes the uterine lining to shed, start of menstruation Menopause- when there is no longer a menstrual cycle, decrease of estrogen and progesterone from the ovaries, ages 45 to 55 Estrus Cycle- only humans and chimpanzees have menstrual cycles, others have this, the uterine lining is reabsorbed instead of shed
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