BIO 210 Notes, Fall 2009

CHAPTER 1 Life in the Balance: An Introduction to Human Biology 1-1 Health and Homeostasis Homeostasis is a state of relative constancy. Human health depends on maintaining healthy physical, psychological, and social environments. Health is a state of physical and mental well-being. Health is dependent on maintaining homeostasis. 1-2 Evolution and the Characteristics of Life The theory of evolution says that all life evolved from earlier forms. Humans are similar to other organisms in many ways. All organisms  are made up of cells  grow and maintain their organization by taking in chemicals and energy from the surroundings  exhibit metabolism  possess homeostatic mechanisms  sense and respond to changes in the environment  are capable of reproduction and growth  are products of evolutionary development and are subject to evolutionary change Humans are one form of life on Earth and have many unique characteristics. 1-3 Understanding Science The scientific method generally starts with observations that lead to hypotheses and experiments to test them. Theories are broad generalizations based on many experimental observations. Science relies on inductive and deductive reasoning. 1-4 Critical Thinking Critical thinking rules allow us to analyze problems, issues, and information for errors of reasoning. CHAPTER 10 The Nervous System 10-1 An Overview of the Nervous System The nervous system not only controls body functions, but also allows for higher functions such as thinking. The nervous system consists of two main anatomical subdivisions, the central and peripheral nervous systems. The peripheral nervous system is divided into two subdivisions: the somatic and the autonomic. 10-2 Structure and Function of the Neuron Neurons consist of a cell body and two types of processes. The myelin sheath greatly increases the rate of transmission of nerve impulses. Nerve cells lose their ability to divide. Neurons are highly susceptible to loss of. Nerve impulses result from the flow of ions across their plasma membranes. Stimulateing a nerve cell increases its permeability to ions, resulting in a change in the resting potential. Nerve impulses are waves of depolarization. Nerve impulses travel from one neuron to another across synapses. Neurotransmitters may excite or inhibit the postsynaptic membrane. Neurotransmitters are quickly removed from the synapses. Many common chemical substances alter synaptic transmission. 10-3 The Spinal Cord and Nerves The spinal cord gives off numerous nerves that supply the body. The nerves attached to the spinal cord carry motor and sensory impulses. Interneurons conncect sensory and motor neurons in the spinal cord. Injury to the spinal cord can cause permanent damage. 10-4 The Brain Cranial nerves are attached to the brain and supply structures in the head and upper body. The cerebral hemispheres function in integration, sensory reception, and motor action. The primary motor cortex controls voluntary movement. The primary sensory cortex receives sensory information from the body. The association cortex is the site of integration and complex intellectual activities. Unconscious functions are housed in the cerebellum, hypothalamus, and brain stem. The cerebellum controls muscle synergy and helps maintain posture. The thalamus is a relay center. The hypothalamus controls many autonomic functions involved in homeostasis. The limbic system is the site of instinctive behavior and emotion The brain stem controls many basic body functions. Cerebrospinal fluid cushions the CNS. Electrical activity in the brain varies depending on activity level or level of sleep. Headaches have many causes. 10-5 The Autonomic Nervous System The ANS controls many body functions not under conscious control. 10-6 Learning and Memory Learning is the acquisition of new information and skills; memory is the storage and recall of that information. Memory is stored in multiple regions of the brain. Short-term and long-term memory may involve changes of the neurons. New evidence suggests that brain function can be retained in old age. 10-7 Diseases of the Brain Loss of memory and confusion in older individuals is often the result of Alzheimer’s disease. Parkinson’s disease is a neurological disorder caused by a lack of dopamine in certain regions of the brain. Multiple sclerosis is caused by the destruction of the myelin sheath of nerve cells in the CNS. Brain tumors afflict the young and the old and may have many causes. 10-8 Health and Homeostasis Nerve cells are highly dependent on glucose for energy production because they cannot use fatty acids to generate energy. CHAPTER 11 The Senses 11-1 The General and Special Senses The human body contains receptors that detect a wide array of internal and external stimuli essential for our well-being. 11-2 The General Senses Receptors for the general body senses generally fit into two groups: naked nerve endings and encapsulated receptors. Naked nerve endings in tissues detect pain, temperature, and light touch. Encapsulated receptors consist of naked nerve endings surrounded by one or more layers of cells. Many receptors stop generating impulses after exposure to stimuli. 11-3 Taste and Smell The special senses include Taste Smell Vision Hearing Balance Taste buds respond to chemicals dissolved in food. Taste buds are preferentially responsive to one flavor. The olfactory epithelium is a patch of receptor cells that detects odors. Smell influences our sense of taste, and vice versa. 11-4 The Visual Sense: The Eye The human eye consists of three distinct layers. The cornea and lens focus light on the retina. Alterations in the shape of the lens and eyeball cause the most common visual problems. 11-5 Hearing and Balance: The Cochlea and Middle Ear The ear consists of three anatomically separate portions: the outer, middle, and inner ears. The Eustachian tube helps to equalize pressure inside the middle ear cavity. Hearing requires the participation of several structures. The vestibular apparatus houses receptors that detect body position and movement. 11-6 Health and Homeostasis Noise pollution in our environment affects homeostasis by disturbing sleep and raising stress levels. CHAPTER 12 The Skeleton and Muscles 12-1 Structure and Function of the Human Skeleton Besides providing internal support, bones play an important role in homeostasis. The human skeleton consists of two parts. All bones have a hard, dense outer layer that surrounds a less compact central region. Bones are remodeled for strength when exposed to new stresses. The joints permit varying degrees of mobility. Arthroscopy permits surgeons to repair injuries with a minimum of trauma. Osteoarthritis is caused by wear and tear on articular cartilage. Rheumatoid arthritis is an autoimmune disease that results in inflammation of the synovial membrane. Most of the bones of the human skeleton start out as hyaline cartilage. Bone helps to maintain proper level of calcium in body. Bone fractures are repaired by fibroblasts and osteoblasts. Osteoporosis involves a loss of calcium, which results in brittle, easy-to-break bones. 12-2 The Skeletal Muscles Skeletal muscles permit a wide range of movements. Skeletal muscle cells are both excitable and contractile. Muscle fibers contain many small bundles of contractile filaments. During muscle contraction, the actin filaments slide inward. Muscle cells use enormous quantities of ATP daily. The strength of muscle contraction can be increased by stimulating (recruiting) additional muscle fibers. Muscle tone results from the contraction of a small number of muscle. Two types of muscle fibers are found in skeletal muscle, slow- and fast-twitch. Exercise builds muscles and increases endurance. 12-3 Health and Homeostasis Intentional misuse of steroids can cause physical, psychiatric, and behavioral problems. CHAPTER 13 The Endocrine System 13-1 Principles of Endocrinology The endocrine system produces hormones that are transported in the blood to distant sites where they influence many functions. Target cells contain receptors for specific hormones. Some hormones stimulate the synthesis and release of other hormones or activate cellular processes. Hormone secretion is often controlled by negative feedback mechanisms. 13-2 The Pituitary and Hypothalamus The pituitary consists of two parts, the anterior and posterior lobes, and produces many hormones. The anterior pituitary secretes seven hormones with widely different functions. Growth hormones stimulate cell growth, primarily targeting muscle and bone. The secretion of growth hormone is controlled by a releasing hormone produced by the hypothalamus. Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to produce thyroxine. ACTH stimulates the release of hormones from the adrenal cortex. The gonadotropins are hormones that stimulate the ovaries and testes. Prolactin stimulates milk production in the breasts of women. The posterior pituitary secretes two hormones. Antidiuretic hormone increases the water absorption in the kidney. Oxytocin facilitates birth and stimulates milk let-down. 13-3 The Thyroid Gland The thyroid gland is located in the neck produces hormones that regulate metabolism, heat production, and calcium levels in the blood. Thyroxine and triiodothyronine accelerate the breakdown of glucose and stimulate growth and development. Calcitonin decreases blood levels of calcium. 13-4 The Parathyroid Glands The parathyroid glands produce a hormone that helps regulate serum calcium levels. 13-5 The Pancreas The pancreas produces two hormones, insulin and glucagon, that control blood glucose levels. Glucagon increases blood levels of glucose, opposing the actions of insulin. Insulin causes blood sugar levels to decline rapidly after a meal. Diabetes is really two diseases with similar symptoms but different causes. Treatments for Type I and Type II diabetes are quite different. 13-6 The Adrenal Glands The adrenal glands consist of inner and outer regions, both of which produce hormones. The adrenal glands lie atop the kidneys and consist of two separate portions: The adrenal medulla The adrenal cortex The adrenal medulla produces stress hormones. The adrenal cortex produces three types of hormones with markedly different functions. 13-7 Health and Homeostasis The endocrine system is sensitive to outside factors. Stress can lead to an imbalance in the adrenal hormones. Toxic pollutants can affect hormonal balance. CHAPTER 14 The Immune System 14-1 Viruses and Bacteria: An Introduction Viruses are nonliving biological agents that invade cells. Many bacteria perform useful functions, while others cause serious diseases. Bacteria are prokaryotic cells that reproduce on their own. Bacteria respond to antibiotics; viruses do not. 14-2 The First and Second Lines of Defense In humans, the first line of defense is a physical and chemical barrier. The body’s second line of defense combats infectious agents that penetrate the first line. The inflammatory response involves chemical and cellular responses. The second life of defense consists of three additional chemicals. 14-3 The Third Line of Defense: The Immune System The cells of the immune system selectively target foreign substances and foreign organisms. Substances that trigger an immune response are large molecular weight molecules. Immature B and T cells are incapable of responding to antigens. B cells provide humoral immunity through the production of antibodies. The initial reaction to an antigen is slower and weaker than subsequent responses. The rapidity of the secondary response results from the production of memory cells. Antibodies destroy antigens in one of four ways: Neutralization Agglutination Precipitation Activation of the complement system T cells attack foreign cells directly. Macrophages play a very important role in humoral and cell-mediated immunity. Two types of immunity are possible: active and passive. The immune system may operate optimally when exposed to antigens early on. Tissue transplants often evoke cell-mediated immunity. 14-4 Diseases of the Immune System Allergies are an immune system overreaction to environmental substances. Autoimmune diseases result from an immune attack on the body’s own cells. 14-5 Health and Homeostasis The protective mechanisms of immunity are needed for body homeostasis. Stress can suppress the immune system. Chapter 15 Human Infectious Disease 15-1 The Infections Agents of Human Disease Many infectious diseases remain dangerous today. Viruses and bacteria are among the most common infectious agents. Fungi, protozoa, and helminthes also cause disease. 15-2 The Course of a Human Disease Pathogens differ in their ability to cause disease. A pathogen produces a set of signs and symptoms. A disease typically follows a series of five stages 15-3 How Pathogens Cause Disease Pathogenicity and virulence depend on key metabolic characteristics of a pathogen 15-4 How Infectious Diseases Are Transmitted Direct transmission may occur through direct physical contact. Diseases can also be transmitted by indirect contact. 15-5 Emerging Infectious Diseases and Bioterrorism Several infectious diseases once thought to be under control are reemerging and new infectious diseases are emerging for a variety of reasons. Bioterrorism is an attempt to use infectious disease agents to frighten and inflict pain and suffering in populations. 15-6 Health and Homeostasis A person’s health partially determines susceptibility to disease. CHAPTER 16 Chromosomes, Cell Division, and The Cell Cycle 16-1 The Cell Cycle The life cycle of a cell is called the cell cycle and consists of two parts: Interphase Cell division Interphase is a period of intense activity and is divided into three parts. Nuclear and cytoplasmic division occur separately. 16-2 The Chromosome Human body cells contain 46 chromosomes that contain the genetic information required to control cellular activity. Chromosomes condense after replication, forming tightly coiled structures in the nucleus. The number of chromatids varies, depending on the stage of the cell cycle. 16-3 Cell Division Mitosis is divided into four stages. Prophase Metaphase Anaphase Telophase Cytokinesis, the division of the cytoplasm, is made possible by contraction of microfilaments beneath the cell membrane. 16-4 Control of the Cell Cycle Many factors appear to control the cell cycle. CHAPTER 17 Principles of Human Heredity 17-1 Meiosis and Gamete Formation During gamete formation, germ cells undergo a special kind of division called meiosis, which reduces the number of chromosomes by half. Meiosis I is a reduction division. Meiosis II is like mitotic division. In males, meiosis produces four gametes, but in females, it produces only one. 17-2 Principles of Heredity Much of our early knowledge on heredity came from the work of Gregor Mendel. Mendel discovered that the traits he was studying did not blend. Parents contribute equally to the characteristics of their offspring. Mendel also discovered the principle of dominance. The genotype of an organism is its genetic makeup; the phenotype is its appearance. Genotypes and phenotypes can be determined by the Punnett square. Genes on different chromosomes segregate independently of one another during gamete formation. 17-3 Mendelian Genetics in Humans Autosomal-recessive traits are expressed only when both alleles are recessive. Autosomal-dominant traits are expressed in all individuals. 17-4 Variations in Mendelian Genetics Incomplete dominance results in intermediate traits—that is, a kind of blending of traits. Some genes have multiple alleles. Some traits are determined by more than one gene pair. Crossing-over is a genetic swapping that occurs in meiosis. The Human Genome Project seeks to determine the sequence of bases in human DNA and the location of all of the genes. 17-5 Sex-Linked Genes The presence or absence of the Y chromosome determines one’s sex. In order for a recessive gene to be expressed, it must be located on both X chromosomes in females, but only one in males. When present, a dominant gene is expressed in males and females. Both dominant and recessive Y-linked genes are always expressed. The action of some genes is influenced by the sex of an individual. 17-6 Chromosomal Abnormalities and Genetic Counseling Abnormal chromosome numbers generally result from a failure of chromosomes to separate during gamete formation (meiosis). This process is called nondisjunction. Genetic disorders may also result from variations in chromosome structure. Genetic screening allows parents to determine whether they will have a genetically normal baby. DNA abnormalities may also occur in mitochondria, resulting in diseases. 17-7 Health and Homeostasis New research bolsters the idea that our personalities are influenced by our genes as well as our environment. CHAPTER 18 How Genes Work and How Genes Are Controlled 18-1 DNA and RNA: Macromolecules with a Mission DNA consists of a double helix held together by hydrogen bonds. DNA unwinds and then serves as a template for the production of new DNA strands. Three types of RNA exist, each of which is involved in protein synthesis. Transfer RNA Ribosomal RNA Messenger RNA RNA synthesis is called transcription and takes place on a DNA template in the nucleus of the cell. 18-2 How Genes Work: Protein Synthesis Protein is synthesized on an mRNA template. Proteins are synthesized by adding one amino acid at a time. This process is called translation. 18-3 Controlling Gene Expression In humans, genetic expression is controlled at four levels: At the chromosome At transcription After transcription but before translation At translation 18-4 Epigenetic Control of Gene Expression Many factors can affect the way the DNA controls affect gene expression:  vitamins  toxic chemicals  maternal behavior The epigenome is part of the biological information a parent passes on to its offspring. 18-5 Health and Homeostasis Mutations may explain most cancers. CHAPTER 19 Genetic Engineering and Biotechnology 19-1 Genetic Manipulation: An Overview Genetic engineering is the newest form of genetic tinkering. 19-2 Cloning Cloning offers us an opportunity to produce identical replicas of existing or extinct organisms. 19-3 Recombinant DNA Technology In recombinant DNA technology, genes are removed from one organism, then spliced into another of the same or a different species. Enzymes are used to cut out segments of genes and insert them elsewhere. Plasmids from bacteria can be used to close DNA fragments for mass production. Genes can be mass produced on strands of mRNA. Genes can also be mass produced using the polymerase chain reaction. 19-4 Applications of Recombinant DNA Technology Hormones and other proteins created from mass-produced genes can be used to treat many diseases. Recombinant DNA techniques can be used to produce vaccines. Gene splicing can be used to transfer genes from one organism to another. Transgenic plants are easier to produce than transgenic animals. Transgenic microbes are some of the most controversial of all creations. Recombinant DNA technology can be used to cure genetic diseases. DNA probes are used for DNA analysis. DNA probes are used to help map human chromosomes. 19-5 Controversies Over Genetic Engineering--Ethics and Safety Concerns Despite its promises, genetic engineering is fraught with controversy over safety and ethics. CHAPTER 2 The Chemistry of Life 2-1 Atoms and Subatomic Particles Atoms are the fundamental unit of all matter. The elements are made up of atoms that are composed of protons, neutrons, and electrons. Isotopes are alternative forms of atoms, differing in the number of neutrons they contain. 2-2 The Making of a Molecule Atoms combine to form molecules. Atoms bond to form more stable configurations. Ionic bonds are electrostatic attractions between two oppositely charged particles. Covalent bonds are formed by the sharing of electrons between atoms. Polar covalent bonds occur any time there is an unequal sharing of electrons by two atoms. Hydrogen bonds form between slightly charged atoms usually on different molecules. Chemical compounds fall into two broad groups: organic and inorganic. 2-3 Water, Acids, Bases, and Buffers Water, an inorganic molecule, is vital to life. Water molecules split into hydrogen and hydroxide ions. Acids are substances that add hydrogen ions to solution; bases remove hydrogen ions. Homeostasis is ensured in part by buffers, molecules that help maintain pH within a narrow range. 2-4 Overview of Other Biologically Important Molecules Carbohydrates, lipids, amino acids, proteins, and nuclei acids are biologically important molecules and are covered in later chapters. 2-5 Health and Homeostasis Environmental imbalances can cause disease. CHAPTER 20 Cancer 20-1 Benign and Malignant Tumors Abnormal cell division may lead to benign tumors, which stop growing, or malignant tumors, which can invade other parts of the body. Cancer cells often migrate to other sites. 20-2 How Cancer Forms The conversion of a normal cell to a cancerous one involves two steps. Mutations in two groups of genes are primarily responsible for cancer. Several physical and biological agents are also responsible for producing cancer. Some carcinogens exert their effect outside of the DNA. Cancers develop many years after the initial exposure to a carcinogen. 20-3 Cancer Treatments Tumors can be removed surgically or treated with chemotherapy and radiation. Stimulating the body to produce antibodies and T cells that attack tumors can help eliminate tumors. Liposomes containing cancer-killing chemicals or monoclonal antibodies attached to chemotherapeutic agents can deliver a lethal dose of these chemicals directly to cancers. Reduced blood vessel development in tumors successfully stops cancers from growing. Blocking genes involved in cell replication or altering their products could help doctors kill cancer cells. Drugs combined with light therapy may prove to be an effective treatment in some forms of cancer. The earlier a cancer is detected and treated, the better one’s chances of survival. Preventing cancer may be the best approach of any. CHAPTER 21 Human Reproduction 21-1 The Male Reproductive System The male reproductive tract consists of the following components: (a) testes, (b) epididymis, (c) vasa deferentia, (d) sex accessory glands, (e) urethra, (f) penis, and (g) scrotum. Sperm are produced in the seminiferous tubules and stored in the epididymis until ejaculation. Semen consists mostly of fluids produced by the sex accessory glands. The prostate enlarges with age and is the site of a common form of cancer in men. Sperm are formed in the seminiferous tubules. The interstitial cells produce the male sex steroid testosterone. Testosterone secretion may lead to acne. The penis contains erectile tissue that fills with blood during sexual arousal. Ejaculation is a reflex mechanism. The male reproductive system is controlled by three hormones: 21-2 The Female Reproductive System The female reproductive tract consists of the ovaries, uterus, and oviducts. The external genitalia are the externally visible parts of the female reproductive system. Many changes occur in women during sexual arousal and orgasm. The ovaries produce ova and release them during ovulation. The menstrual cycle consists of cyclic changes in hormone levels, the uterus, and the ovaries. Pituitary hormones stimulate follicle development, ovulation, and ovarian hormone production. The uterine lining, or endometrium, also undergoes cyclic changes during the menstrual cycle. Fertilization prevents the uterine lining from being sloughed off The female sex steroids, estrogen and progesterone, have numerous effects. Premensteral syndrome is a condition afflicting many women. Menopause is the cessation of menstruation. 21-3 Birth Control Contraceptive measures help prevent pregnancy. Abstinence Surgical Sterilization Birth control pill Diaphragm Condom Vaginal sponge Jellies and creams Withdrawal Abortion is the surgical termination of pregnancy. Many contraceptives are currently being tested for use in men. 21-4 Infertility Infertility is fairly common among reproductive age couples 21-5 Health and Homeostasis The human reproductive system is essential for the survival of the species. CHAPTER 22 Human Development and Aging 22-1 Fertilization Fertilization occurs in the upper third of the oviduct. Very few sperm make it to the site of fertilization. Sperm travel by swimming and muscular contraction of the female reproductive tract. Sperm contain enzymes that help them penetrate the protective layers surrounding the egg. Only one sperm can fertilize an egg. Sperm and egg nuclei join to create a zygote with 46 chromosomes. 22-2 Pre-embryonic Development Pre-embryonic development begins at fertilization and ends at implantation. The embryo embeds in the wall of the uterus. Implantation occasionally occurs outside of the uterus. Placental hormones are essential to reproduction. The amnion forms from the inner cell mass. 22-3 Embryonic Development Embryonic development ends when the organs are more or less formed. 22-4 Fetal Development During fetal development organs continue to develop and grow. The fetal circulatory system contains three bypasses around the lungs and liver. 22-5 Birth Defects Birth defects include structural and functional defects that appear in a newborn. 22-6 Childbirth and Lactation Uterine muscle contractions are stimulated by a change in hormonal levels. Childbirth occurs in three stages. The dilation The expulsion The placental Milk production, or lactation, is controlled by the hormone prolactin. 22-7 Aging and Death Aging is the progressive deterioration of the body. Aging occurs as a result of a decline in cell numbers and their function. Although declines in body function occur with age, we can age in a healthy fashion, living out our later years in good health, free of disease. The likelihood of contracting diseases of old age largely depends on lifestyle. Death may be defined by the loss of brain or heart and pulmonary function. 22-8 Health and Homeostasis Radiation from VDTs might help cause miscarriages, but further research is needed to verify the connection. CHAPTER 23 Human Evolution 23-1 The Evolution of Life The formation of organic molecules from inorganic molecules is chemical evolution. The theory of chemical evolution is supported by several convincing experiments. Some scientists believe that the chemical building blocks for life arose from outer space. The earliest cells were probably aggregations of polymers that acquired nutrients directly from the environment Eukaryotes probably arose by endosymbiotic evolution Eukaryotes gave rise to multicellular organisms 23-2 How Evolution Works Genetic variation is the raw material of evolution. Natural selection is a process by which organisms become better adapted to their environment. Natural selection ensures that the fittest organisms in a population survive and reproduce. 23-3 The Evidence Supporting Evolution The fossil record yields some of the best supporting evidence for evolution. Common anatomical features in different species support the theory of evolution. The common biochemical makeup of organisms also supports the theory of evolution. Studies of common developmental patterns support the theory of evolution. Experimental evidence supports the theory of evolution by natural selection. The study of biogeography helps explain evolution. 23-4 Early Primate Evolution Primates evolved from an insect-eating mammal The fossil evidence of primate evolution is limited, making it difficult to determine the exact progression of early human ancestors. 23-5 Evolution of Australopithecines The earliest hominids were members of the genus Australopithecus 23-6 Evolution of the Genus Homo The first truly humanlike organisms were called Homo habilis. Homo habilis gave rise to Homo erectus. Modern humans belong to Homo sapiens. Human races result from variations caused by geographic separation. 23-7 Health and Homeostasis Evolution has resulted in the presence of many homeostatic mechanisms. CHAPTER 24 Ecology and the Environment 24-1 An Introduction to Ecosystems Ecology is the study of the interaction between organisms, including humans, and their environment. The biosphere is the zone in which all life exists on Earth. The biosphere is divided into biomes and aquatic life zones. Ecosystems consist of organisms and their environment. Habitat is where an organism lives. An organism’s niche consists of all of an organism’s relationships in an ecosystem. 24-2 Ecosystem Function Producers generate nutrients consumed by all other organisms. Organisms are part of food webs. Energy and nutrients flow through food webs, but in very different ways. The organisms of a food chain exist on different trophic levels. Nutrient cycles consist of two phases, the organismic and environmental. Water cycle Carbon cycle Nitrogen cycle Succession is the progressive development of biological communities 24-3 Overshooting the Earth’s Carrying Capacity The carrying capacity of the environment is the number of organisms it can sustain indefinitely. In many countries the human population is exceeding food production. Many resources are in short supply and will be depleted in the near future Pollution from human activities exceeds the environment’s assimilative capacity 24-4 Overpopulation: Problems and Solutions Overpopulation is a condition in which populations exceed the ability of the environment to supply resources and/or assimilate wastes Overpopulation is a problem in virtually all countries, rich and poor Reducing population growth will help reduce environmental problems 24-5 Resource Depletion: Eroding the Prospects of All Organisms Humanity is