Excretion, Reproduction, and Development ~Biology AP~ Excretion A Meridian Biology AP Study Guide by Tim Qi, Willy Zhang, and Jeff Gu Osmolarity: moles of osmotically active particles per liter of solvent Osmoconformers Usually any marine invertebrate that regulates its internal salinity such that it is always equal to the surrounding seawater (body fluid isotonic to environment) Osmoregulators Human kidneys participate in the active regulation of the osmotic pressure of bodily fluids to maintain the homeostasis of the body's water content. Nitrogen Waste Ammonia Very soluble in water and highly toxic. Therefore o Needs to be execreted constantly o Or converted into a less toxic form. Generally exreted by organisms that live in the water, such as hydras and fish. Urea (Ureotelic) Not as toxic as ammonia Excreted by earthworms and humans In mammals, it is formed in the liver from ammonia Uric Acid (Uricotelic) Paste-like substance that is not soluble in water and is not very toxic Excreted by insects, reptiles, and birds, with minimum water loss. Other Excretory Systems Protonephridia 1) Fluid enters near the flame bulbs into the complex tubules around the body. 2) The constant beating of the cilia inside the flame bulb moves the fluid through the tubules. 3) As the fluid flows through the tubules, it is modified by the tubules (reabsorption and secretion) 4) Final wastes leave through the nephridiopore on the side of the body. Copyright 2006 (April 6 th ) All rights reserved. Bio AP Study Guide v2.6 by Meridian Notes. Do not distribute or reproduce without replicating this copyright.
Metanephridia 1) Blood pressure pushes fluid into coelem (the space between the organs and ectoderm). 2) Fluid is pushed into nephrostomes. 3) As the fluid flows through the collecting tubules, it is modified. 4) Waste exits through the nephridiopore. Malpighian Tubules 1) Salts ions, and uric acid are actively transported from body into tubules while water moves in through osmosis. 2) Contractions in the hindgut move the fluid from the tubules towards the intestine. 3) Uric acid precipates while salt, ions, are reabsorbed by tubules (water follows through osmosis). 4) Uric acid mixes with digested wastes in the small intestine and is expelled through the anus. Kidney System Terms Filtration Secretion Filtration occurs as blood pressure (about twice that of capillaries outside the kidney) forces fluid from the blood in the glomerulus into Bowman s capsule. Secretion is the active, selective uptake of molecules that did not get filtered into Bowman s capsule. This occurs in the
Re absorption Excretion proximal and distal tubules. The process by which most of the water and solutes (glucose, amino acids, and vitamins) that initially entered the tubule during filtration are transported back in to the peritubular capillaries and, thus, back to the body. Excretion is the removal of metabolic wastes, for example, nitrogenous wastes. Everything that passes into the collecting tubule is excreted from the body. The Nephron Major Structures Glomerulus A tightly packed ball of capillaries found in the region of the kidney called the renal cortex. Bowman s capsule Encapsulates the glomerulus. This is the site of filtration. Proximal tubule It is the site of substantial secretion and absorption. One of the most important functions is the reabsorption of most of the NaCl and water from the filtrate volume. In addition, the cells that line the proximal tubule maintain a constant ph in body fluids by controlling the secretion of hydrogen ions. Descending limb The descending limb of the loop of Henle is permeable to water but not to salt. Water travel out of the limb from the filtrate due to osmosis. Ascending limb The ascending limb of the loop of Henle is impermeable to water but freely permeable to salt. NaCl diffuses out of the lower part of the ascending limb and is actively transported out of the upper part of the ascending loop, increasing the high osmolarity of salt in the interstitial tissue. Distal tubule Another important site of secretion and reabsorption. Like the proximal tubule, it also contributes to ph regulation. Collecting duct Carries the remaining filtrate through tissue that has very high osmolarity. Whether additional water is removed or not depends on the presence of antidiuretic hormone (ADH). If ADH is present, the walls of the collecting duct become permeable to water and the filtrate become very hypertonic. If ADH is not present, the walls remain impermeable to water and the urine remains hypotonic. Path of Urine: Kidneys Ureter Bladder Urethra Antidiuretic Hormones
Osmoreceptors in hypothalamus ADH (Pituitary Gland) Stimulus: The release of ADH triggered by detection of increase blood osmolarity H2O reabsorption helps prevent further osmolarity increase Homeostasis: Blood osmolarity Reproduction Forms of Reproduction Sexual Female creates eggs and male fertilizes Asexual All other forms of an organism recreating or replicating itself. Advantages of Each Sexual Asexual The diversity of the young will be greater and have less chance of developing abnormalities. Greater efficiency than sexual reproduction allows for faster and more recreation. Forms of Asexual Reproduction Budding Smaller forms are created and bud off the original. IE. Hydra & yeast Binary Fission Splits in two IE. Most forms of bacteria Regeneration If broken, the organism can replace most parts of it s body, and broken pieces can create new copies of original IE. Starfish Parthenogenesis Eggs hatch unfertilized. IE. Bees, whiptail lizards Forms of Sexual Reproduction Internal Fertilization Male deposits sperm in female, and fertilization occurs in the female.
External Fertilization Females release eggs in a wet environment and males fertilize afterwards. Gametogenesis: Meiotic process in which gametes are produced. Eggs and sperms. Oogenesis Occurs in ovaries. Each meiosis II cycle creates 1 egg and 3 polar bodies (small) When female is embryo, all primary cells (oocytes) are already frozen Each month, one unfreezes and goes through meiosis II The division of cytoplasm is much greater on the egg because it will create a larger target for the sperm Sermatogenesis Occurs in testes Each meiosis cycle produces 4 full sperm cells. Matures in epididymis and gains tail Produced constantly Midsection contains much mitochondrion for energy use traveling to the egg. The headpiece has Aerosome in the front to digest the egg membrane and burrow through to the center. Male Reproductive Anatomy Seminal vesicle Produces sugar and proteins that will cover more than half of the actual semen ejaculated. Urinary bladder Stores urine filtered from the kidneys. Connected to urethra to eject urine. Prostate gland Secretes clotting enzymes which will lower hostility of the uterus Bulbourethral gland Creates alkaline fluid to neutralize the acid of the uterus Urethra Tube through the penis which carry urine and sperm. Never both at the same time. Erectile tissue of Tissue that is engorged with blood during erection of penis. penis Scrotum Sac containing Testes, epididymis, and part of the vas deferens. Vas deferens Tube connection epididymis to ejaculatory duct to transport sperm. Epididymis Contains the mature sperm produced by the testis Glans penis External male sex organ. The penis is the male reproductive organ, and also used for urination. Testis Production of sperm. Ejaculatory duct Connects the epididymis to the urethra. Prepuce A retractable piece of skin which covers part of the genitals. Male Hormones Hormone Effects during embryonic development Effects during puberty Testosterone Causes the embryo s Voice deepens reproductive system to Hair growth develop into male. Testis/penis growth Enlargement of muscles Stimulate sperm production Luteinizing Hormone LH None Causes cells in testes to produce more testosterone Foillice Stimulating None Causes more spermatogenesis Hormone FSH GnRH None Stimulates release of LH and FSH
GnRH released by hypothalamus Anterior pituitary secretes LH FSH Leyding cells in testes make testosterone Sertoli cells make sperm Inhibit Hypothallimus and Anterior pituitary Inhibin Inhibit Hypothallimus and Anterior pituitary Female Reproductive Anatomy Cervix The lower, narrow portion of the uterus where it joins with the top end of the vagina. Vagina The tube leading from the uterus to the exterior of the body. Bartholin s gland Secretes mucus to increase lubrication. Oviduct (fallopian 2 tubes leading from the ovaries to the uterus. Where the actual tubes) fertilization occurs Ovary Two reproductive sacs where first stage eggs are stored frozen until signaled to be ready to be fertilized. Uterus The uterus is where the baby is formed. The walls will thicken and thin based on the period cycle. Urinary bladder Holds urine filtered from the kidneys. Urethra Tube where urine is extracted the body from the bladder. Shalt (Clitoris) Homologous to the male organ, but does not contain any sexual Glans (Clitoris) reproductive function. Solely functions to induce sexual pleasure. Prepuce (Clitoris) Labia minora Derived from the latin word lip and includes the lip like structures in the exterior of the vagina. Labia majora Surrounds the labia minora. Follicles Contains the ovum from which the egg is released. Corpus luteum Endometrium Secretes estrogen and progesterone Developed in preparation for the receiving of a fertilized egg. If egg is not fertilized, endometrium will deteriorate, opening the cervix again. (Uterus lining) Female Hormones Hormone Effects during puberty Effects during Menstrual Cycle Estrogen Stimulate the development of sexually mature characteristics. Stimulates the thickening and growth of the endometrium (uterine Vagina, uterus, and lining) breasts are enlarged. Negative feedback on
Pelvis becomes broader levels of LH and FSH (first Increased fat and pubic 12 days of cycle) hair growth Triggers serge of LH and Menstrual cycle begins FSH around day 12 Luteinizing Hormone - LH Increased levels stimulate the production of estrogen and progesterone in the ovaries Rising levels cause the follicles to mature in the ovaries Estrogen levels rise Follicle Stimulating Hormone - FSH Increased levels stimulate the production of estrogen. Progesterone is released when Rising levels cause the follicles to mature in the ovaries the corpus luteum matures. Estrogen levels rise Progesterone Same as estrogen Maintains the endometrium GnRH Triggers release of FSH and LH Triggers release of FSH and LH Female Menstrual Cycle Development Acrosomal Reaction The acrosome is a cell organelle at the head of the sperm that releases digestive enzymes that allows it to get inside the egg. The acrosome will release the enzymes to break down the egg s outer membrane while altering the sperms plasma membrane so it can fuse with the egg s plasma membrane. Receptors on the egg ensure correct fertilization from the same species. Stages of Development Cleavage: The Zygote (earliest stage of embryo) will undergo rapid cell divisions through mitosis with no significant growth in size. The cells that undergo mitosis during cleavage are all totipotent stem cells can become any kind of cell when the embryo is complete. Blastula Formation: When a Morula (ball of cells formed from the zygote) starts to move away from the center, forming a hollow fluid filled cavity (bastocoel), a blastula is formed.
It is at the blastula stage when the embryo will implant itself on the walls of the endometrium. Trophoblast cells will mold onto the blastula, forming the earliest stage of the placenta. Gastrulation: Cells migrate in the gastrula to form the three different embryonic germ layers that will later be tissue layers and body axes. Three Embryonic Germ Layers Name Layer Forms Endoderm Inner Digestive tract, respiratory tract, pancreas, and liver Mesoderm Middle Muscle, bones, excretory system, circulatory system, and most of reproductive system Ectoderm Outer Nervous system, skin, hair, nails, sweat and oil glands. Archenteron: A partly empty space within the endodermic gastrula that will develop into the digestive tract. Organogenesis: The three germ layers will shift around to develop the internal organs. Neurulation: The first stage of organogenesis where the nervous system is formed from the ectoderm. Steps of Neurulation: A neural plate forms on the posterior side of the gastrula as it thickens and hardens The neural plate forms into a tube as the edges of the neural plate moves toward each other The edges of the neural plate fuse together cutting off the neural tube from ectoderm Notochord: flexible, rod-shaped body found under the neural tube. It is composed of cells derived from the mesoderm and defining the primitive axis of the embryo that will develop into the vertebrae. Neural Tube Defects: o Anencephaly: When top of the neural tube fails to close, this results in absence of the brain, skull, and/or other cranial organs. o Spina Bifida: When bottom of the neural tube fails to close, this results in malformation of the spinal cord. Development in Mammals: All mammalian fetuses are contained in multiple membranes known as the amniotic sac which nourish and protect the embryo. These liquid embryos are evolution adaptations to living on land.