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Chapters 41-47 Internal regulation • Interstitial fluid: internal fluid environment of vertebrates; exchanges nutrients and wastes • Homeostasis: “steady state” or internal balance • Negative feedback: change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation; i.e., body temperature • Positive feedback: physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change; i.e., uterine contractions at childbirth Metabolism: sum of all energyrequiring biochemical reactions • Catabolic processes of cellular respiration • Calorie; kilocalorie/C • Endotherms: bodies warmed by metabolic heat • Ectotherms: bodies warmed by environment • Basal Metabolic Rate (BMR): minimal rate powering basic functions of life (endotherms) • Standard Metabolic Rate (SMR): minimal rate powering basic functions of life (ectotherms) Chapter 41 • Animal Nutrition Nutritional requirements • Essential nutrients: materials that must be obtained in preassembled form • Essential amino acids: the 8 amino acids that must be obtained in the diet • Essential fatty acids: unsaturated fatty acids • Vitamins: organic coenzymes • Minerals: inorganic cofactors Food types/feeding mechanisms • • • • • Opportunistic Herbivore: eat autotrophs Carnivore: eat other animals Omnivore: both Feeding Adaptations – Suspension-feeders: sift food from water (baleen whale) – Substrate-feeders: live in or on their food (leaf miner) (earthworm: deposit-feeder) – Fluid-feeders: suck fluids from a host (mosquito) – Bulk-feeders: eat large pieces of food (most animals) Overview of food processing Earthworm http://www.tvdsb.on.ca/westmin/science/snc2g1/wormdig.htm Bird http://people.eku.edu/ritchisong/birddigestion.html Grasshopper http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb6pg17.htm • 1-Ingestion: act of eating • 2-Digestion: process of food break down – – – – enzymatic hydrolysis intracellular: breakdown within cells (sponges) extracellular: breakdown outside cells (most animals) alimentary canals (digestive tract) • 3- Absorption: cells take up small molecules • 4- Elimination: removal of undigested material Mammalian digestion • Peristalsis: rhythmic waves of contraction by smooth muscle • Sphincters: ring-like valves that regulate passage of material • Accessory glands: salivary glands; pancreas; liver; gall bladder http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter43/animations.html# Mammalian digestion • Oral cavity – salivary amylase- carbs – •bolus • Pharynx – •epiglottis • • Esophagus Stomach: protein – •gastric juice •pepsin/pepsinogen (HCl) – •acid chyme – •pyloric sphincter • • Small intestine •duodenum Intestinal digestion: – – – – a-carbohydrate b-protein c- nucleic acid d-fat •bile http://www.whfoods.com/genpage.php?tname=faq&dbid=16#digestion Bile http://www.zerobio.com/cck_flash.htm Mammalian digestion Mammalian digestion • • • • Villi / microvilli Lacteal (lymphatic) Chylomicrons (fats mixed with cholesterol) Hepatic portal vessel: to liver Mammalian digestion • Hormonal Action: • Gastrin food---> stomach wall ---> gastric juice • Enterogastrones (duodenum) – 1-Secretin acidic chyme---> pancreas to release bicarbonate – 2-Cholecystokinin (CCK) amino/fatty acids---> pancreas to release enzymes and gall bladder to release bile • • • • • Large intestine (colon) Cecum Appendix Feces Rectum/anus Evolutionary adaptations • • • • Dentition: an animal’s assortment of teeth Digestive system length Symbiosis Ruminants Chapter 42 • Circulation and Gas Exchange Circulation system evolution, I • Gastrovascular cavity (cnidarians, flatworms) • Open circulatory •hemolymph (blood & interstitial fluid) •sinuses (spaces surrounding organs) • Closed circulatory: blood confined to vessels • Cardiovascular system: •heart (atria/ventricles) •blood vessels (arteries, arterioles, capillary beds, venules, veins) •blood (circulatory fluid) http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html Circulation system evolution, II Earthworm http://yucky.discovery.com/noflash/worm/multi/heart.mov • Fish: 2-chambered heart; single circuit of blood flow • Amphibians: 3-chambered heart; 2 circuits of blood flowpulmocutaneous (lungs and skin); systemic (some mixing) • Mammals: 4-chambered heart; double circulation; complete separation between oxygen-rich and oxygen poor blood Pulmonary/systemic http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12704 Double circulation Heart anatomy http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12504 The mammalian heart Cardiac cycle http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0028-swf_the_cardiac_cy.swf • Cardiac cycle: sequence of filling and pumping • Systole- contraction • Diastole- relaxation • Cardiac output: volume of blood per minute • Heart rate- number of beats per minute • Stroke volume- amount of blood pumped with each contraction • Pulse: rhythmic stretching of arteries by heart contraction Blood flow http://www.sumanasinc.com/webcontent/animations/content/human_heart.html The heartbeat • • • Sinoatrial (SA) node (“pacemaker”): sets rate and timing of cardiac contraction by generating electrical signals Atrioventricular (AV) node: relay point (0.1 second delay) spreading impulse to walls of ventricles Electrocardiogram (ECG or EKG) Open heart surgery http://www.abc.net.au/science/lcs/swf/heart.swf Blood vessel structural differences Capillary fluid exchange http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0029-swf_fluid_exchange.swf Away Low pressure Toward heart Thicker: more pressure Gas exchange, osmosis, diffusion The lymphatic system • • • • Lymphatic system: system of vessels and lymph nodes, separate from the circulatory system, that returns fluid and protein to blood Lymph: colorless fluid, derived from interstitial fluid Lymph nodes: filter lymph and help attack viruses and bacteria Body defense / immunity Blood • • • • • • Plasma: liquid matrix of blood in which cells are suspended (90% water) Erythrocytes (RBCs): transport O2 via hemoglobin Leukocytes (WBCs): defense and immunity Platelets: clotting Stem cells: pluripotent cells in the red marrow of bones Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia; thrombus (clot) Cardiovascular disease • • • • • • • Cardiovascular disease (>50% of all deaths) Heart attack- death of cardiac tissue due to coronary blockage Stroke- death of nervous tissue in brain due to arterial blockage Atherosclerosis: arterial plaques deposits Arteriosclerosis: plaque hardening by calcium deposits Hypertension: high blood pressure Hypercholesterolemia: LDL, HDL Gas exchange • CO2 <---> O2 • Aquatic: gills , ventilation, countercurrent exchange • Terrestrial: •tracheal systems •lungs Mammalian respiratory systems • Larynx (upper part of respiratory tract) • Vocal cords (sound production) • Trachea (windpipe) • Bronchi (tube to lungs) • Bronchioles • Alveoli (air sacs) • Diaphragm (breathing muscle) How do we breathe? • • • • • • • Thoracic cavity pleura diaphragm intercostal muscles Role of pressure inspiration What happens with pressure and the volume of the chest cavity? • Expiration • What happens with pressure and the volume of the chest cavity? Respiratory System • Why do we need to breathe? • Gas exchange system • Requirements of respiratory membranes: – must be moist. – Must be thin – must be permeable to gases. • All organisms must have a mechanism with which to transport gases. (circulatory system) • Movement of gases happens by simple diffusion. Breathing • Positive pressure breathing: pushes air into lungs (frog) • Negative pressure breathing: pulls air into lungs (mammals) • Inhalation: diaphragm contraction; Exhalation: diaphragm relaxation • Tidal volume: amount of air inhaled and exhaled with each breath (500ml) • Vital capacity: maximum tidal volume during forced breathing (4L) • Regulation: CO2 concentration in blood (medulla oblongata) Gas Exchange • Where does it occur? • What gases are exchanged? • Simple diffusion is responsible. • Erythrocytes • RBCs • Role of hemoglobin • Structure of hemoglobin • • • • Oxyhemoglobin 4 oxygens at a time. Effects of CO Carbon dioxide is largely transported as a dissolved gas in the plasma although some is transported by hemoglobin Respiratory pigments: gas transport • Oxygen transport– Hemocyanin: found in hemolymph of arthropods and mollusks (Cu) – Hemoglobin: vertebrates (Fe) • Carbon dioxide transport– Blood plasma (7%) – Hemoglobin (23%) – Bicarbonate ions (70%) http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/animation__gas_exchange_during_respiration.html Control of breathing • Respiratory Center – Medulla Oblongata – Brainstem • Peripheral Chemoreceptors • aorta and carotid arteries • increase in Carbon dioxide increases H+ ion concentration. • Central chemoreceptors in the brain are sensitive to this. • Increase CO2, Increase breathing rate. • Hyperventilation Other mechanisms of breathing • Gills • Structure • Why do fish suffocate on land? • Countercurrent flow • Insects - spiracles – tracheae – tracheoles • Why can’t this work in us? • Snail and Frogs – Have lungs, but very little respiratory surface area. – Cutaneous Breathing. Chapter 43 • The Body’s Defenses Lines of Defense Nonspecific Defense Mechanisms…… Phagocytic and Natural Killer Cells • Neutrophils 60-70% WBCs; engulf and destroy microbes at infected tissue • Monocytes 5% WBCs; develop into…. • Macrophages enzymatically destroy microbes • Eosinophils 1.5% WBCs; destroy large parasitic invaders (blood flukes) • Natural killer (NK) cells destroy virus-infected body cells & abnormal cells The Inflammatory Response • 1- Tissue injury; release of chemical signals~ • histamine (basophils/mast cells): causes Step 2... • prostaglandins: increases blood flow & vessel permeability • 2/3- Dilation and increased permeability of capillary~ • chemokines: secreted by blood vessel endothelial cells mediates phagocytotic migration of WBCs • 4- Phagocytosis of pathogens~ • fever & pyrogens: leukocyte-released molecules increase body temperature Specific Immunity • Lymphocyctes •pluripotent stem cells... • B Cells (bone marrow) • T Cells (thymus) • Antigen: a foreign molecule that elicits a response by lymphocytes (virus, bacteria, fungus, protozoa, parasitic worms) • Antibodies: antigen-binding immunoglobulin, produced by B cells • Antigen receptors: plasma membrane receptors on b and T cells Self/Nonself Recognition • • • Self-tolerance: capacity to distinguish self from non-self Autoimmune diseases: failure of self-tolerance; multiple sclerosis, lupus, rheumatoid arthritis, insulin-dependent diabetes mellitus Major Histocompatability Complex (MHC): body cell surface antigens coded by a family of genes – Class I MHC molecules: found on all nucleated cells – Class II MHC molecules: found on macrophages, B cells, and activated T cells • • • Antigen presentation: process by which an MHC molecule “presents’ an intracellular protein to an antigen receptor on a nearby T cell Cytotoxic T cells (TC): bind to protein fragments displayed on class I MHC molecules Helper T cells (TH): bind to proteins displayed by class II MHC molecules Clonal selection • Effector cells: short-lived cells that combat the antigen • Memory cells: long-lived cells that bear receptors for the antigen • Clonal selection: antigen-driven cloning of lymphocytes Types of immune responses • Humoral immunity (outside cell) – B cell activation – Production of antibodies – Defend against bacteria, toxins, and viruses free in the lymph and blood plasma • Cell-mediated immunity (inside) – T cell activation – Binds to and/or lyses cells – Defend against cells infected with bacteria, viruses, fungi, protozoa, and parasites; nonself interaction Helper T lymphocytes • Function in both humoral & cell-mediated immunity – Stimulated by antigen presenting cells (APCs) – T cell surface protein CD4 enhances activation – Cytokines secreted (stimulate other lymphocytes): a) interleukin-2 (IL-2): activates B cells and cytotoxic T cells b) interleukin-1 (IL-1): activates helper T cell to produce IL-2 Humoral response: B cells • Stimulated by T-dependent antigens (help from TH cells) – Macrophage (APCs) with class II MHC proteins – Helper T cell (CD4 protein) – Activated T cell secretes IL-2 (cytokines) that activate B cell • B cell differentiates into memory and plasma cells (antibodies) Antibody Structure & Function • Epitope: region on antigen surface recognized by antibodies • 2 heavy chains and 2 light chains joined by disulfide bridges • Antigen-binding site (variable region) 5 classes of Immunoglobins • • • • • IgM: 1st to circulate; indicates infection; too large to cross placenta IgG: most abundant; crosses walls of blood vessels and placenta; protects against bacteria, viruses, & toxins; activates complement IgA: produced by cells in mucous membranes; prevent attachment of viruses/bacteria to epithelial surfaces; also found in saliva, tears, and perspiration IgD: do not activate complement and cannot cross placenta; found on surfaces of B cells; probably help differentiation of B cells into plasma and memory cells IgE: very large; small quantity; releases histamines-allergic reaction Antibody-mediated Antigen Disposal 1) Neutralization (opsonization): antibody binds to and blocks antigen activity 2) Agglutination: antigen clumping 3) Precipitation: cross-linking of soluble antigens 4) Complement fixation: activation of 20 serum proteins, through cascading action, lyse viruses and pathogenic cells Cell-mediated: cytotoxic T cells • Destroy cells infected by intracellular pathogens and cancer cells – Class I MHC molecules (nucleated body cells) expose foreign proteins – Activity enhanced by CD8 surface protein present on most cytotoxic T cells (similar to CD4 and class II MHC) • TC cell releases perforin, a protein that forms pores in the target cell membrane; cell lysis and pathogen exposure to circulating antibodies Induction of Immune Responses • Primary immune response: lymphocyte proliferation and differentiation the 1st time the body is exposed to an antigen • Plasma cells: antibody-producing effector B-cells • Secondary immune response: immune response if the individual is exposed to the same antigen at some later time~ Immunological memory Immunity in Health & Disease • Active immunity: long term/ – natural: conferred immunity by recovering from disease – artificial: immunization and vaccination; produces a primary response • Passive immunity: short term transfer of immunity from one individual to another – natural: mother to fetus; breast milk – artificial: rabies antibodies • ABO blood groups (antigen presence) • Rh factor (blood cell antigen); Rhmother vs. an Rh+ fetus (inherited from father) Abnormal immune function • Allergies – hypersensitive responses to environmental antigens (allergens); mast cells release histamine causes dilation and blood vessel permeability, epinephrine – Antihistamines can relieve symptoms anaphylactic shock: life threatening reaction to injected or ingested allergens. • Autoimmune disease: – The system turns against the body’s own molecules – Examples: multiple sclerosis, lupus, rheumatoid arthritis, insulin-dependent diabetes mellitus • Immunodeficiency disease: – Immune components are lacking, and infections recur • Ex: SCIDS (bubble-boy); A.I.D.S. Chapter 44 • Regulating the Internal Environment Homeostasis: regulation of internal environment • Thermoregulation internal temperature • Osmoregulation solute and water balance • Excretion nitrogen containing waste Regulation of body temperature • Thermoregulation • 4 physical processes: – Conduction: transfer of heat between molecules of body and environment – Convection: transfer of heat as water/air move across body surface – Radiation: transfer of heat produced by organisms – Evaporation: loss of heat from liquid to gas • Sources of body heat: – Ectothermic: determined by environment – Endothermic: high metabolic rate generates high body heat Regulation during environmental extremes • Torpor: physiological state of low activity; decrease in metabolic rate – 1- Hibernation: long term or winter torpor (winter cold and food scarcity); bears, squirrels – 2- Estivation: short term or summer torpor (high temperatures and water scarcity); fish, amphibians, reptiles • Both often triggered by length of daylight Water balance and waste disposal • Osmoregulation: management of the body’s water content and solute composition • Nitrogenous wastes: breakdown products of proteins and nucleic acids; ammonia-very toxic • Ammonia: most aquatic animals, many fish • Urea: mammals, most amphibians, sharks, bony fish (in liver; combo of NH3 and CO2) • Uric acid: birds, insects, many reptiles, land snails Osmoregulators • Osmoconformer: no active adjustment of internal osmolarity (marine animals); isoosmotic to environment • Osmoregulator: adjust internal osmolarity (freshwater, marine, terrestrial) • Freshwater fishes (hyperosmotic)- gains water, loses; excretes large amounts of urine salt vs. marine fishes (hypoosmotic)- loses water, gains salt; drinks large amount of saltwater hyperosmotic Because I’m a marine fish, I’m hypoosmotic (less solute in me than the water) so I lose lots of water and therefore need to excrete small amounts of urine. Because I’m a freshwater fish, I’m hyperosmotic (more solute in me than the water), so I take in a lot of water and therefore excrete a lot of water! hypoosmotic Excretory Systems • Production of urine by 2 steps: – Filtration (nonselective) – Reabsorption (secretion of solutes) • • • • Protonephridia: flatworms (“flame-bulb” systems) Metanephridia: annelids (ciliated funnel system) Malpighian tubules: insects (tubes in digestive tract) Kidneys: vertebrates Excretory Parts • • • • • • • • • Renal artery/vein: kidney blood flow Ureter: urine excretory duct Urinary bladder: urine storage Urethra: urine elimination tube Renal cortex (outer region) Renal medulla (inner region) Nephron: functional unit of kidney Cortical nephrons (cortex; 80%) Juxtamedullary nephrons (medulla; 20%) http://www.physiology.ubc.ca/undergrad_files/transport.swf http://www.sumanasinc.com/webcontent/an imations/content/kidney.html Nephron Structure • Afferent arteriole: supplies blood to nephron from renal artery • Efferent arteriole: blood from glomerulus • Glomerulus: ball of capillaries • Bowman’s capsule: surrounds glomerulus • Proximal tubule: secretion & reabsorption • Peritubular capillaries: from efferent arteriole; surround proximal & distal tubules • Loop of Henle: water & salt balance • Distal tubule: secretion & reabsorption • Collecting duct: carries filtrate to renal pelvis http://www.lakemichigancollege.edu/liberal/bio/anat/urin.html http://www.biologymad.com/resources/kidney.swf http://www.getbodysmart.com/ap/urinarysystem/kidney/externalanatomy/tutorial.html secretion and reabsorption secretion and reabsorption reabsorbs water, salt, some urea •Loop of Henle: reabsorption of water and salt Kidney regulation: hormones http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter20/animation__hormonal_communication.html • Antidiuretic hormone (ADH) ~ secretion increases permeability of distal tubules and collecting ducts to water (H2O back to body); inhibited by alcohol and coffee • Juxtaglomerular apparatus (JGA) ~ reduced salt intake-->enzyme renin initiates conversion of angiotension (plasma protein) to angiotension II (peptide); increase blood pressure and blood volume by constricting capillaries • Angiotension II also stimulates adrenal glands to secrete aldosterone; acts on distal tubules to reabsorb more sodium, thereby increasing blood pressure (renin-angiotensionaldosterone system; RAAS) • Atrial natriuretic factor (ANF) ~ walls of atria; inhibits release of renin, salt reabsorption, and aldosterone release http://www.health.bcu.ac.uk/physiology/renalsystem.htm#top http://www.wisc-online.com/objects/AP2204/AP2204.swf Chapter 45 Chemical Signals in Animals • The endocrine system and the nervous system are structurally, chemically, and functionally related. Regulatory systems • Hormone: chemical signal secreted into body fluids (blood) communicating regulatory messages • Target cells: body cells that respond to hormones • Endocrine system/glands: hormone secreting system/glands (ductless); exocrine glands secrete chemicals (sweat, mucus, enzymes) through ducts • Neurosecretory cells: specialized nerve cells that secrete hormones • Feedback mechanisms: negative and positive (feature that is also common in the nervous system) Mode of Action: Chemical Signaling • 1- Plasma membrane reception • signal-transduction pathways (neurotransmitters, growth factors, most hormones) • 2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators Signal Transduction Pathway • Signaltransduction pathways allow for small amounts of a hormone to have a large effect. Local regulators: cells adjacent to or near point of secretion • Growth factors: proteins for cell proliferation • Nitric oxide (NO): (highly reactive& potentially toxic) neurotransmitter; cell destruction (bacteria, cancer cells); vessel dilation • Prostaglandins: modified fatty acids secreted by placenta (induce labor) and immune system (fever, pain); also found in semen (contract smooth muscle in uterus helping convey sperm to egg. Vertebrate Endocrine System Page 961 • Tropic hormones: a hormone that has another endocrine gland as a target • Hypothalamus:causes release of hormones produced by posterior pituitary and regulates anterior pit. • Pituitary gland • Pineal gland • Thyroid gland • Parathyroid glands • Thymus • Adrenal glands • Pancreas • Gonads (ovary, testis) •Melatonin: biological rhythms •Calcitonin: lowers blood calcium •Thyroxine: metabolic processes •(PTH): raises blood calcium T cells Islets of Langerhans (clusters of endocrine cells that secrete hormones) Alpha cells: glucagon: raises blood glucose levels Beta cells: insulin : lowers blood glucose levels Type I diabetes mellitus (insulin-dependent; autoimmune disorder, attack mounted on pancreas cells) Type II diabetes mellitus (non-insulin-dependent; reduced responsiveness in insulin targets) Adrenal medulla (catecholaminessynthesisized from AA tyrosine): •epinephrine & norepinephrine: increase basal metabolic rate (blood glucose and pressure) Adrenal cortex (corticosteroids): •glucocorticoids (cortisol): raise blood glucose •mineralocorticoids (aldosterone): reabsorption of Na+ and K+ The hypothalamus & pituitary • Releasing and inhibiting hormones • Anterior pituitary: – Growth (GH)~bones • √gigantism/dwarfism • √acromegaly – Prolactin (PRL)~mammary glands; milk production – Follicle-stimulating (FSH) & – Luteinizing (LH): ovaries/testes – Thyroid-stimulating (TSH): thyroid – Adrenocorticotropic (ACTH): adrenal cortex – Melanocyte-stimulating (pigment cells)(MSH) – Endorphins: natural ‘opiates’; brain pain receptors The pituitary • The posterior pituitary: • Oxytocin: uterine and mammary gland cell contraction • Antidiuretic (ADH): retention of water by kidneys, increase permiability of epithelium to water, amplifies water reabsorption (dark yellow, stinky urine) The pineal, thyroid, & parathyroid The pancreas The adrenal glands The gonads • Steroid hormones: precursor is cholesterol • androgens (testosterone): sperm formation; male secondary sex characteristics, gonadotropin • Estrogens (estradiol):uterine lining growth; female secondary sex characteristics; gonadotropin • Progestins (progesterone)~uterine lining growth Chapter 46 Animal Reproduction • • • • • Asexual (one parent) fission (parent separation) budding (corals) gemmules (porifera) fragmentation & regeneration (inverts) • Sexual (fusion of haploid gametes) • • • • gametes (sex cells) zygote (fertilized egg) ovum (unfertilized egg) spermatozoon (male gamete) Reproductive cycles • Parthenogenesis unfertilized egg development; haploid, sterile adults (honeybees) • Hermaphroditism both male & female reproductive systems; sessile & burrowing organisms (earthworms) • Sequential hermaphroditism reversal of gender during lifetime •protogynous (female 1st) •protandrous (male 1st) Mechanisms of sexual reproduction • Fertilization (union of sperm and egg) • external • internal • Pheromones chemical signals that influence the behavior of others (mate attractants) Mammalian reproduction • The Human Male • • • • Testes: male gonads Leydig cells: hormone production Scrotum:outside body temp. Seminiferous tubules: where sperm is made • Epididymis: where it matures • Vas deferens: (tubing) sperm propulsion • Penis/urethra (exit tube) Add fluids – Seminal vesicles: semen – Prostate gland:anticoagulant; nutrients – Bulbourethral glands: acid neutralizer Spermatogenesis • Puberty until death! • Seminiferous tubules~ location • Primordial germ cell (2N)~ differentiate into…. • Spermatogonium (2N)~ sperm precursor • • • • • • • Repeated mitosis into…. Primary spermatocyte (2N) 1st meiotic division Secondary spermatocyte (1N) 2nd meiotic division Spermatids (1N)~Sertoli cells…. Sperm cells (1N) The Human Female •where fertilization happens •female gonads pituitary1) FSH: follicle enlargement 3)LH: follicle ruptures, releases egg egg capsule: secrets 2)estrogen: begin build up, LH Secretes 4)progesterone: •womb/lining Continue build up of uterine lining Egg not fertilized, progesterone decreases, lining shed, FSH increases •sperm receptacle Oogenesis • • • • • • • • • • As embryo until menopause... Ovaries Primordial germ cells (2N) Oogonium (2N) Primary oocyte (2N) Between birth & puberty; prophase I of meiosis Puberty; FSH; completes meiosis I Secondary oocyte (1N); polar body Meiosis II; stimulated by fertilization Ovum (1N); 2nd polar body The female pattern • Estrous cycles/estrus (many mammals) • Menstrual cycle (humans and many other primates): • Ovarian/Menstrual cycles~ •follicular phase~follicle growth •ovulation~ oocyte release •luteal phase~ hormone release Embryonic & fetal development • • • • • Gestation~ pregnancy 1st trimester: organogenesis fetus (week 8; all adult features) HCG hormone (menstruation override; pregnancy test detection) • Parturition~birth • Labor~uterine contractions • Lactation~prolactin & oxytocin Modern technologies Chapter 47 Animal Development A Body-Building Plan for Animals • It is difficult to imagine that each of us began life as a single cell, a zygote • A human embryo at about 6–8 weeks after conception shows development of distinctive features LE 47-1 1 mm Minutes Seconds LE 47-5 1 Binding of sperm to egg 2 3 4 Acrosomal reaction: plasma membrane depolarization (fast block to polyspermy) 6 8 10 Increased intracellular calcium level 20 Cortical reaction begins (slow block to polyspermy) 30 40 50 1 Formation of fertilization envelope complete 2 Increased intracellular pH 3 4 5 Increased protein synthesis 10 20 30 40 60 90 Fusion of egg and sperm nuclei complete Onset of DNA synthesis First cell division Cleavage • Fertilization is followed by cleavage, a period of rapid cell division without growth • Cleavage partitions the cytoplasm of one large cell into many smaller cells called blastomeres LE 47-7 Fertilized egg Four-cell stage Morula Blastula • The eggs and zygotes of many animals, except mammals, have a definite polarity • The polarity is defined by distribution of yolk, with the vegetal pole having the most yolk • The development of body axes in frogs is influenced by the egg’s polarity LE 47-8 Point of sperm entry Animal hemisphere Vegetal hemisphere Point of sperm entry Anterior Right Ventral Gray crescent Vegetal pole Future dorsal side of tadpole First cleavage Dorsal Left Posterior Body axes Animal pole Establishing the axes • Cleavage planes usually follow a pattern that is relative to the zygote’s animal and vegetal poles LE 47-9 Zygote 0.25 mm 2-cell stage forming 4-cell stage forming Eight-cell stage (viewed from the animal pole) 8-cell stage 0.25 mm Animal pole Blastula (cross section) Blastocoel Vegetal pole Blastula (at least 128 cells) • Meroblastic cleavage, incomplete division of the egg, occurs in species with yolk-rich eggs, such as reptiles and birds LE 47-10 Fertilized egg Disk of cytoplasm Zygote Four-cell stage Blastoderm Cutaway view of the blastoderm Blastocoel BLASTODERM YOLK MASS Epiblast Hypoblast LE 47-17 Amnion Allantois Embryo Amniotic cavity with amniotic fluid Albumen Shell Yolk (nutrients) Chorion Yolk sac • Holoblastic cleavage, complete division of the egg, occurs in species whose eggs have little or moderate amounts of yolk, such as sea urchins and frogs Gastrulation • Gastrulation rearranges the cells of a blastula into a three-layered embryo, called a gastrula, which has a primitive gut LE 47-15 Eye Neural tube Notochord Forebrain Somite Heart Coelom Archenteron Endoderm Mesoderm Lateral fold Blood vessels Ectoderm Somites Yolk stalk YOLK Yolk sac Form extraembryonic membranes Early organogenesis Neural tube Late organogenesis Developmental Adaptations of Amniotes • Embryos of birds, other reptiles, and mammals develop in a fluid-filled sac in a shell or the uterus • Organisms with these adaptations are called amniotes • In these organisms, the three germ layers also give rise to the four membranes that surround the embryo