Review Sheet for BIOL 240W Exam II:

Transcription

1 Review Sheet for BIOL 240W Exam II: Kearn Kaur A. Excretion/Osmoregulation 1. Definition of Osmoregulation: General term for processes by which animals control solute concentrations and balance water gain/loss. Organisms which live in different environments must maintain a solute concentration in their cells that maintain life while preventing dehydration or flooding/cell explosion. 2. Why do organisms omsoregulate: They do because it balances out the uptake/loss of water and solutes. Cells balance water gain and loss through osmoregulation, a process based on the controlled movement of solutes between internal fluids and the external environment and on the movement of water, which follows osmosis. 3. Differences between an osmoconformer and osmoregulator Osmoconformers: Are isoosmotic with their surroundings, no tendency to lose/gain water, and do not regulate their osmolarity - Only marine organisms, tend to live in environments that are fairly stable in solute concentration, many marine invertebrates(osmoconformers) Osmoregulators: Expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment - Must discharge or take in water depending on the osmolarity of the environment - Osmoregulation allows organisms to live in a wide range of habitats including freshwater and terrestrial habitats Main Difference: An osmoconformer do not regulate their osmolarity; there is an equal movement of water between the animal and its environment. An osmoregulator uses energy to control the amount of water it gains and loses; there is an unequal movement of water between the animal and its environment. 4. Environments where conforming is beneficial and why 5. Meaning of Stenohaline and Euryhaline Stenohaline Animals that cannot tolerate a wide range of changes in external osmolarity Euryhaline Animals which can survive fluctuations in external osmolarity Example organisms Cod Osmoregulator, Stenohaline, Saltwater, Ocean is hyperosmotic to internal environment, and constantly lose water to the environment and gain salt from diffusion and food. Regulation: Drink large amounts of seawater, chloride ions are actively transported out through gills and sodium ions passively follow, and kidneys remove other waste products Perch Osmoregulator, Stenohaline, Freshwater, Environment is hypoosmotic to internal environment, constantly gain water by osmosis and loss salt via diffusion, and body fluids generally have lower solute concentrations than those of saltwater fish. Regulation: Excrete large amounts of dilute urine, salt lost by diffusion and via urine are replaced by foods and by uptake across gills (have spec. cells) Salmon Osmoregulator, Euryhaline, Freshwater and Saltwater, Environment is hypoosmotic to internal environment and the opposite in saltwater. Regulation: Drink lots of seawater and excrete excess salt from gills, to prevent drying out (ocean environments). Stop drinking and produce large amounts of dilute urine, gills start to take up salt from environment, to prevent cells from shriveling (freshwater environments) 6. Adaptations for regulation of solute concentrations in osmoregulators Animals in wet and dry environments: Anyhydrobiosis the ability to survive in a dormant state when the organism s environment dries up (ex: water bears).

2 Land Animals: Prone to drying out, they have to reduce water loss. Done by body coverings that prevent dehydration, nocturnal behavior to reduce evaporative water loss, drinking and eating moist foods, using metabolic water, and very concentrated excretions Tissues to regulate solute movements: Transport epithelia, one or more layers of specialized cells that regulate salt movement (salt glands in seabirds contain transport epithelia) 7. Three types of excretory substances and organisms that use each Ammonia: Very soluble, very toxic, only tolerated in low concentrations, common in aquatic species because it requires high water intake and lots of excretion, lost through diffusion (gills and body surface) and kidneys Examples: fish Urea: Lower toxicity, good for land animals because they can carry it around with them and requires less water (more concentrated solutions are tolerated), requires energy to produce it from ammonia Examples: mammals, most adult amphibians, sharks, and some marine bony fishes and turtles Uric Acid: Low toxicity, not very soluble in water so can be excreted as a paste with little water loss; most energy is expended in this Examples: Land snails, insects, birds, and many reptiles 8. How excretory substances are suited to an animal s environment Ammonia: A lot of water is needed, good for fish. Not suitable for land animals, very toxic and lots of water Urea: Good for land animals, less water needed. Energy needs to be expended to produce it from ammonia Uric acid: Most energy expended, requires less water loss 9. Benefit of uric acid in egg-laying animals Uric acid precipitates out of solution and can be stored within the egg as a harmless solid left behind when the animal hatches, not very toxic, is tolerable 10. The four main excretory processes Filtration: The excretory tubule collects a filtrate from the blood. Water and solutes are forced by blood pressure across the selectively permeable membranes of a cluster of capillaries and into the excretory tubule. Reabsorption: The transport epithelium reclaims valuable substances (glucose, certain salts, vitamins, hormones, and amino acids) from the filtrate and returns them to the body fluids Secretion: Other substances (nonessential solutes and wastes) such as toxins and excess ions are extracted from body fluids and added to the contents of the excretory tubule. Excretion: The altered filtrate (urine) leaves the system and the body 11. Overview of protonephridia, metanephridia, Malpighian tubules, and kidneys Protonephridia: In flatworms, form a network of dead-end tubules, which are connected to external openings, branch throughout the flatworm body, lacks a coelom (body cavity). Are capped by a flame bulb with a tuft of cilia that draws water and solutes from the interstitial fluid, through the flame bulb, and into the tubule system. Metanephridia: Most annelids (earthworms), is another tubular excretory system, consist of internal openings that collect body fluids from the coelom through a ciliated funnel, the nephrostome, and release the fluid to the outside through the nephridiopore. Malpighian tubules: Insects and other terrestrial arthropods have these organs that remove nitrogenous wastes and also function in osmoregulation. These open into the digestive system and dead-end at tips that are immersed in the hemolymph. Kidneys: In Vertebrates, are compact, non-segmented organs containing numerous tubules arranged in a highly organized manner. The vertebrate excretory system includes a dense network of capillaries intimately associated with the tubules, along with ducts and other structures that carry urine out of the tubules and kidney and eventually out of the body. 12. Definition and examples of anhyrobiosis Dehydration dooms most animals, but some aquatic invertebrates living in temporary ponds and films of water around soil particles can lose almost all their body water and survive in a dormant state, called anhydrobiosis, when their habitats dry up. - The sugar, Trehalose, is an adaptation in water bears that allows them to keep their cell membrane intact, it seems to protect cells by replacing water associated with membranes and proteins. B. Hormones 1. Define trophic hormones Are hormones that regulate the function of endocrine glands. 2. Hormonal cascade Signals to the brain stimulate the hypothalamus to secrete a hormone that stimulates or inhibits release of a trophic hormone for a specific gland 3. Know in detail the form and function of at least 3 human endocrine glands A. Hypothalamus: Role in maintaining homeostasis in controlling temp., Cardio. Sys, regulating food/water intake, control sleep/wake cycle (circadian cycle), moods, and libido.

3 1. Location: Below thalamus and above pituitary glands, allows it to control release of 8 hormones from pituitary gland, easy access to central nervous system allowing immediate control over metabolic processes because located near part of the brain stem 2. Hormones produced/stored: TRH, GnRH, GHRH, CRH, Somatostatin, and Dopamine 3. What their hormones do: TRH (release of thyroid stimulating hormone), GnRH (triggers sexual development), GHRH (stimulates cells in anterior lobe of pituitary to secrete growth hormones, CRH (acts on cells in anterior of pituitary to release adrenocorticotrophic hormone), Somatostatin (inhibits the release of growth hormone and thyroid stimulating hormone), and Dopamine (inhibits the release of prolactin also involved in the feeling of happiness and reward). 4. How their action is regulated: Connection to central nervous system allows it to receive signals that set off different sensing regions, input/release mechanism responds and hormones are synthesized 5. Associated Disease: Hypothalamic disease, caused by head trauma, genetic disorders, radiation, eating disorders, and surgery. Example if GHRH is not properly produced there is poor growth, treated with hormonal replacement therapy B. Pituitary (posterior and anterior): 1. Location: In the middle of the base of the brain (base of hypothalamus). Works closely with the hypothalamus; the pituitary gland receives signals from hypothalamus which determines when to produce/store/release hormones 2. Hormones produced/stored: ACTH, FSH, GH, LH, TSH, and prolactin in anterior (synthesizes and secretes hormones). ADH and Oxytocin in posterior (doesn t produce hormones itself, it stores/releases neurohormones produced by hypothalamus and later secretes them). 3. What their hormones do: ACTH (stimulates secretion of glucocorticoids), FSH (stimulates production of gametes), GH (stimulates growth, metabolic functions), LH (stimulates testes and ovaries), TSH (stimulates thyroid gland), prolactin (stimulates milk production and secretion) in anterior. ADH (promotes water retention in kidneys), Oxytocin (stimulates uterine contractions, mammary gland cells) in posterior. 4. How their action is regulated: By regulating hormone production and secretion, the pituitary gland directs certain biological processes by stimulating activity in other glands. Pituitary gland and hypothalamus work together to control biochemical processes necessary to maintain homeostasis 5. Associated Disease: Noncancerous tumors by imbalance in hormones, results in dysfunctional pituitary gland, causes hormonal imbalances, lead to headaches, vision problems, and other health issues. Tumor growth can be stimulated by injuries, certain prescribed. Meds, and med. Conditions C. Thyroid: 1. Location: Front and sides of neck near the trachea, location allows for correct regulation of its hormones, on ventral surface of trachea so hormones can obtain iodine, from ingestion of food, needed to function properly. 2. Hormones produced/stored: Thyroid hormone (T 3 and T 4 ) and calcitonin. 3. What their hormones do: Regulate development, maturation, normal bp, heart rate, and muscle tone. Thyroid hormones (body metabolism, its secretion is controlled by hypothalamus and pituitary glands hormone cascade pathway) and calcitonin (maintain Ca levels in blood, is secreted when Ca level in blood is high) 4. How their action is regulated: The regulation allows for appropriate responses because of its form, hormone cascade. One thing is controlled by another and vice. Hormones travel in blood allowing for the correct receptors to receive the signals. 5. Associated Disease: Hyperthyroidism, having overactive thyroid gland, results in jitters, increased stress, and irritability. D. Parathyroid: Solely for calcium regulation, control calcium levels in blood 1. Location: In neck, behind the thyroid gland. 2. Hormones produced/stored: PTH 3. What their hormones do: Released into blood to increase Ca levels 4. How their action is regulated: Regulated by the calcium in blood and managed much like the way the body maintains the set point temperature, through homeostasis 5. Associated Disease: Hyperparathyroidism occurs when one cell inside the normal parathyroid gland goes out of control and begins to reproduce itself until a large tumor develops, results in high abundance of Calcium released into blood, slowly destroying any tissue. E. Pancreas: 1. Location: Below stomach and liver, and above large intestine (near all major digestive tract organs). Near liver, 2 organs work together; pancreas secretes insulin enabling liver to store glucose and glycogen, or secretes glucagon enabling liver to convert glycogen to glucose for energy.

4 2. Hormones produced/stored: Insulin (beta cells), Glucagon (alpha cells) 3. What their hormones do: Insulin (controls amount of glucose in blood), Glucagon (released when blood sugar drops low, liver is stimulated to convert stored glucagon to glucose for the blood to take to cells in the body), 4. How their action is regulated: Antagonistic effects of insulin and glucagon help maintain blood glucose levels in normal blood range, their effects are vital to managing fuel storage and consumption by body cells. 5. Associated Disease: Acute pancreatitis, linked to alcohol consumption, swelling and inflammation of pancreas, the enzymes the pancreas produces and are usually not active until they reach the small intestine become active in pancreas and they eat and digest tissues of pancreas. F. Adrenal: 2 sections Adrenal cortex and Adrenal medulla 1. Location: Located over kidneys, allows for the hormones to be secreted directly into bloodstream, the hormones are then able to be travel through the body to the vital organs. 2. Hormones produced/stored: Epinephrine (noradrenaline) and Norepinephrine (adrenaline) (in Medulla) and Glucocorticoids and Mineralocorticoids (in Cortex) 3. What their hormones do: Noradrenaline and Adrenaline are linked to nervous system they are secreted as a response to stress, whether extreme pleasure or life-threatening situation. They increase chemical energy available for immediate use (fight-or-flight situation). Glucocorticoids (glucose metabolism, raising blood sugar level), Mineralocorticoids (mineral metabolism, maintaining salt and water balance). 4. How their action is regulated: Mineralocorticoids increase blood volume and pressure and Glucocorticoids increase blood glucose level, both work to help the blood. Noradrenaline and adrenaline work to increase blood pressure, breathing rate, and metabolic rate. 5. Associated Disease: Hyperaldosteronism, overproduction of the mineralocorticoid aldosteronism which regulates salt and water balance. Leads to problems in controlling bp. G. Gonads: Testes and Ovaries 1. Location: Male and Female located at the lower end of the midsection. Males, scrotum (holds testes) is located outside body for better temp regulation since sperm are ideal at lower temp. Female, connected to uterus via a tube to which egg can be transported for fertilization and development 2. Hormones produced/stored: Males secrete Androgens, Females secrete Estrogen and Progestin 3. What their hormones do: Androgens (support the formation of sperm and promote make sex characteristics), Estrogen and Progestin (Promote growth and development of uterine lining and female characteristics). Crucial to sexual and reproductive cycles of humans 4. How their action is regulated: Regulation of hormones produced that are formed from gonads is based on a cascade pathway. FSH and LH from anterior pituitary gland control the synthesis of the hormones, both of which are controlled by GnRH from hypothalamus. 5. Associated Disease: Hypogonadism in testes, testes don t produce enough testosterone. May result in infertility, erectile dysfunction, sex drive issues, etc. Cause by testicular trauma, meds, pituitary disorders, etc. H. Pineal 1. Location: Center of mammalian brain, near hypothalamus. The gland is controlled by neurons in the hypothalamus called SCN, located near hypothalamus which helps. Also its input needs to gather from light sources from retina of eye, so located near optic chiasm. 2. Hormones produced/stored: Melatonin 3. What their hormones do: Melatonin regulates functions related to light and seasons. Related to sexual development and daily activity levels. Also affects skin pigmentation in vertebrates. 4. How their action is regulated: Regulated by SCN by receiving light-sensitive neurons in eyes retina, which regulated melatonin production using daylight cycle, dependent on length of night because that s when it s secreted. Body can then monitor activity levels and control reproductive time periods. Since amount of hormone influences sleep cycle and activity level, its regulation depending on length of night allows for appropriate physiological responses. 5. Associated Disease: Melatonin deficiency, inability to secrete melatonin by pineal gland, causes insomnia. Symptoms include anxiety, lower basal body temp, immune suppression, etc. Symptoms can be relieved by exposure to artificial light after sundown, reducing stress, etc. C. Reproduction 1. Contrast sexual and asexual reproduction, and evolutionary advantages/disadvantages of each Asexual: Disadvantages Limited to introduction of genetic variation, no mixing of genetic material Advantages No mate needed, create numerous offspring quickly, perpetuates advantageous genotypes in a stable environment

5 Sexual: Disadvantages need mate, cooperative behavior, need reproductive organs with structural adaptations Advantages Increases genetic variability among offspring, enhances reproductive success of parents when environmental factors change rapidly 2. Describe fission, budding, and fragmentation Fission: Asexual reproduction, a parent separates into two or more approximately equal-sized individuals Budding: Asexual reproduction, new individuals arise from out growths of existing ones Fragmentation: The body breaks into several pieces, some or all of which develop into complete adults 3. Describe hermaphroditism and parthenogenesis Hermaphroditism: One individual functions as both a male and a female, helps if can t find another mate of opposite sex, some capable of self-fertilization, each individual receives and donates sperm; twice as many offspring are produced. Parthenogenesis: An unfertilized egg develops without being fertilized, examples in bees, wasps, and ants. Whiptail Lizards example, no male so female plays male role. 4. Contrast evolutionary benefits of internal/external fertilization Internal (Sperm deposited in or near female reproductive tract and fertilization occurs within the tract): Advantages Higher survival rate because of shelter provided and no predatory action, no environmental problem, can occur anywhere no restrictions. External (Eggs are released by the female in wet environment, where they are fertilized by the male): Advantages More offspring produced. Disadvantages Need moist environment for sperm and egg to swim 5. Discuss with examples, the different trade-offs made by animals with inter/external fertilization 6. Discuss the environmental restrictions upon external fertilization Requires moist habitat to prevent gametes from drying out and to allow the sperm and eggs to swim D. Development 1. Describe the 5 stage process of fertilization 1. Contact: The sperm contacts the egg s jelly coat, triggering exocytosis of the sperm s acrosome. 2. Acrosomal Reaction: Hydrolytic enzymes enable the acrosomal process to penetrate the egg s jelly coat. The tip of the acrosomal process adheres to special receptor proteins on the egg s surface. These receptors extend through the vitelline layer, just external to the egg s plasma membrane; this lock-and-key recognition ensure that eggs will be fertilized only by sperm of the same species. 3. Contact and fusion of sperm and egg membranes : depolarization prevents additional sperm from fusing with the egg s plasma membrane, fast block to polyspremy. 4. Cortical reaction: Cortical granules (egg vesicles) in the egg fuse with the plasma membrane. The secreted contents clip off sperm-binding receptors and cause the fertilization envelope to form. This acts as a slow block to polyspermy. 5. Entry of sperm to nucleus. 2. Define polyspremy and the mechanisms that avoid it 3. Describe cleavage using the terms animal pole, vegetal pole, and cleavage furrow 4. What is morphogenesis 5. Describe gastrulation and define the 3 germ layers and some of their derivatives 6. Describe organogenesis and the development of the notochord, neural tube, neural crest, somites, mesenchyme, and coelom

6 7. The role of cytoplasmic determinants and inductive signals in specifying cell fate 8. Difference between axis formation and pattern formation