final_exam_studyguide.pdf BIOL 123N
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This 12 page Study Guide was uploaded by Megan Nichols on Thursday April 21, 2016. The Study Guide belongs to BIOL 123N at Old Dominion University taught by DOUGLAS J MILLS in Spring 2016. Since its upload, it has received 11 views. For similar materials see GENERAL BIOLOGY II Lecture in Biological Sciences at Old Dominion University.
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Date Created: 04/21/16
THE INNATE IMMUNE SYSTEM The human immune system -‐ The body contains numerous ecological niches for parasites, pathogens, and tumors. o Consequently, the body requires an effective immune system to defend against multiple internal and external threats. Our skin creates a physical shield against foreign invaders. -‐ Adipocytes (fat cells)-‐ in the skin secrete the anti-‐microbial compound cathelicidin. -‐ Sebum and sweat contain o B-‐defensin peptides tat attach microbial membranes. o Fatty acids that create an acidic surface (the acid mantle) that limits microbe growth. -‐ Low nutritional value -‐ Dry surface -‐ Frequent shedding -‐ White blood cells Mucous membranes form a chemical and physical barrier -‐ This specialized epithelial tissue covers and defends all internal body surfaces exposed to the outside world. -‐ They line the digestive, reproductive, and respiratory tracts and contain-‐ o Antibodies that target foreign invaders for elimination by macrophages. o White blood cells called phagocytes that uptake foreign invaders by phagocytosis and destroy them. o Chitinase enzymes that attach fungal cell walls. o Lysozyme enzymes that attack bacterial cell walls. o Mucous that acts like fly paper. The mucous escalator reduces the risk of respiratory infections -‐ The cilia of cells lining the respiratory tract move the mucous containing trapped particles towards the throat for expulsion by coughing, sneezing, urination, or defecation. The digestive tract -‐ Saliva contains anti-‐microbials including antibodies, amylase, lipase, lactoferrin, and peroxidase. -‐ Mutualistic microbes reduce the risk of infection and autoimmunity. -‐ Low pH and the enzyme pepsin limit microbe growth. -‐ Digestive enzymes limit microbe growth. Fever eliminates the ecological niches of some invaders -‐ Fever stimulates-‐ o Interferon production o Phagocytosis o Tissue repair -‐ Fever reduces-‐ o Iron levels in the blood o Tissue injury by increasing heat shock protein production. -‐ Some cold-‐blooded animals move to warmer habitats when infected to stimulate the fever response. -‐ Epinephrine increases the muscle tone to release more heat. -‐ Brain damage from a fever generally will not occur unless the fever is > 107.6 -‐ 106.7 can be lethal Phagocytes are a group of white blood cells -‐ They are specialized to detect, capture, import, and destroy foreign invaders. o They import foreign invaders by phagocytosis. Pattern recognition receptors -‐ Phagocytes use PRRs to recognize the unique molecular characteristics of each major pathogen group. (bacteria, fungi, viruses and worms. o PRRs are strategically located in the cell membrane and within the cell. Macrophages (big eaters) are phagocytes -‐ They patrol exposed areas of the body to search for foreign invaders. o They alert other parts of the immune system that foreign invaders are present. -‐ They are garbage collectors that eat-‐ o Dead cells o Foreign invaders tagged for dispersal. o Toxin molecules tagged for dispersal. -‐ They kill virus-‐infected cells and cancer cells using tumor necrosis factor. -‐ They activate-‐ o Natural killer cells. o Helper t-‐cells that regulate the acquired immune system. -‐ They contribute to inflammation and recruit neutrophils to inflamed tissues. -‐ They regulate the enteric nervous system to control the passage of food through the intestines. Natural killer cells are white blood cells -‐ NK cells induce apoptosis in bacteria, fungus, and worms -‐ NK cells induce apoptosis in cancer cells and our viral-‐infected cells whose surfaces display-‐ o No or few class I MHC (major histo-‐complatability) molecules that are normally recognized by the NK cells don’t kill receptor. o Stressed out molecules recognized by the NK cells kill receptor. The inflammatory system (inflammation) -‐ Histamine release from mast cells and cytokine release from activated macrophages and neutrophils activates inflammation. -‐ Increased blood flow to the inflamed area delivers materials that-‐ o Cause blood clotting. o Contain, neutralize, and destroy (anti-‐microbials, neutrophils) invaders. o Increase the temperature of the inflamed area. o Increase sensitivity to pain. o Coordinate tissue repair. Inflammation must be precisely regulated -‐ This response must be precisely activated and deactivated to reduce the tissue damage that relates to-‐ o Asthma o Chronic peptic ulcer o Rheumatoid arthritis o Crohn’s disease o Chronic sinusitis o Active hepatitis The complement system consists of 30 types of proteins in blood and tissue fluid secreted by the liver and activated macrophages -‐ It tags bacteria for phagocytosis by phagocytes. -‐ It attaches pathogens to one another to neutralize them. -‐ IgG antibodies bind to foreign cell surfaces to stimulate formation of the membrane attach complex. -‐ It stimulates inflammation and alerts the immune system of an invasion. -‐ The membrane attach complex forms in foreign, unprotected cell membranes without protectin (CD59) and DAF (decay accelerating factor) molecules. SPECIFIC DEFENSES OF THE HUMAN BODY ACQUIRED (ADAPTIVE) IMMUNITY Lymphocytes are a type of white blood cell -‐ Lymphocytes are the basis of the acquired immune system-‐ o B-‐cells secrete antibodies that tag foreign invaders for elimination. o Cytotoxic T-‐cells destroy our infected cells and cancerous cells. o Helper-‐t cells stimulate the activity of B-‐cells and cytotoxic t-‐cells. o Natural killer cells also are recognized as lymphocytes. An antigen stimulates a response from lymphocytes -‐ An antigen is a foreign substance recognized by a lymphocyte o An antigen receptor on the lymphocyte surface binds to a specific part of an antigen called the epitope. o An antigen receptor secreted by an activated b-‐cell is an antibody. Lymphocytes produce 11 million unique antigen receptors -‐ Each lymphocyte has 100,000 copies of one, unique antigen receptor on its surface. o This increases its ability to detect a specific antigen. Gene re-‐arrangement yields 11 million unique antigen receptors -‐ This antigen-‐receptor genes in each b-‐cell and t-‐cell are re-‐arranged to code for an antigen receptor with an unique antigen binding site. o 200 possible V exon and J exon combinations can occur in each cell resulting in 200 different nucleotide sequences. -‐ Mutation further increases the number of possible nucleotide sequences. -‐ Alternative splicing further increases the number of possible nucleotide sequences. The spleen contains lymphocytes -‐ The spleen screens blood for foreign invaders, disease-‐causing proteins, toxins, and cancer cells. o B-‐cells, t-‐cells, and macrophages within the spleen detect and eliminate antigens circulating in the blood. The lymphoid organs contain lymphocytes -‐ Lymphoid organs screen lymph fluid for foreign invaders, disease-‐causing proteins, toxins, and cancer cells. o B-‐cells, t-‐cells, and macrophages in the lymphoid organs detect and eliminate antigens circulating in the blood. An antibody is a secreted antigen receptor -‐ When a b-‐cell receptor (antigen receptor) binds to a specific antigen, the b-‐cell becomes activated and secretes a soluble version of the b-‐cell receptor called an antibody (immunoglobulin). o The secreted antibodies bind to the antigen in the body’s fluid. o Each activated b-‐cell secretes 2,000 antibodies per second for 5 days. The defensive functions of antibodies -‐ Neutralization deactivates the antigen. -‐ Opsonization marks the antigen for elimination by phagocytes o The Fc receptor of phagocytes recognizes the Fc part of the antibody. -‐ Activation of the complement system results in the formation of the membrane attack complex in the cell membrane of foreign cells and membranous envelope of viruses. Humoral response neutralizes threats that exist outside of our cells -‐ B-‐cells secrete antibodies that bind to specific epitopes of antigens in the blood, tissue fluid, and lymph fluid. The humoral response -‐ An activated b-‐cell divides to produce populations of-‐ o Plasma cells that secrete 2,000 antibodies per second for 5 days. o Memory cells that migrate to the site of initial infection where they are positioned to respond rapidly to the next invasion. The cell-‐mediated response is specialized to eliminate threats within our cells -‐ Cytotoxic t-‐cells induce apoptosis (programmed cell death) in our infected cells and cancer cells. Cytotoxic t-‐cells recognize our compromised cells -‐ The antigen receptors (TCR) or cytotoxic t-‐cells recognize and bind to foreign (non-‐self) protein fragments that class I MHC molecules display on the surface of our cells. Helper t-‐cells are regulatory lymphocytes -‐ They secrete chemical regulators called cytokines that instruct b-‐cells and t-‐cells to-‐ o Activate o Develop o Divide o Migrate to infected sites o Secrete antibodies (b-‐cells only) o Produce a specific type of antibody (b-‐cells only) Lymphocytes are produced in the bone marrow -‐ Adult stem cells are the source of lymphocytes. Lymphocytes must be self-‐tolerant -‐ Self-‐reactive lymphocytes are eliminated by apoptosis or permanent deactivation to achieve self-‐tolerance. o Developing b-‐cells are screened for self-‐reactivity in the bone marrow. o Developing t-‐cells are screened for self-‐reactivity in the thymus. The breakdown of self tolerance causes auto-‐immunity -‐ Alopecia areata o Bald spots appear. -‐ Anemia o Red blood cell destruction -‐ Lupus erythematosus o DNA/RNA/protein complexes are attacked. -‐ Multiple sclerosis o Myelin sheath destruction. -‐ Myasthenia gravis o Acetylcholine receptors are blocked. -‐ Rheumatoid arthritis o Inflammation injuries joints. -‐ Type I diabetes o Beta cell destruction eliminates insulin production. Immunological memory -‐ When a b-‐cell, cytotoxic cell, or helped t-‐cell is stimulated by antigen recognition, it divides to produce daughter cells. -‐ Some of the daughter cells develop into memory-‐ o B-‐cells o Cytotoxic t-‐cells o Helper t-‐cells -‐ These memory cells migrate to the site of initial invasion, or remain at the site of their formation, where they are positioned to respond rapidly to the next invasion. -‐ The memory cells enable a much more rapid response to antigen detection in the future. Vaccination induces immunological memory -‐ Vaccination, also called immunization, stimulates the production of memory b-‐cells and memory t-‐cells that recognize epitopes of a specific antigen of a specific pathogen. -‐ Vaccines can consist of-‐ o Dead pathogens o Attenuated (disabled) live pathogens o Proteins of pathogens o Genes of pathogens o Harmless relatives of pathogens GAS EXCHANGE IN ANIMALS RESPIRATORY SYSTEMS Gas exchange in single-‐cell microbial species -‐ Their gas exchange needs are satisfied by the diffusion of gas molecules across the cell membrane. o Every part of the cell membrane contacts the surrounding air, or water, to increase the capacity of gas diffusion. o Diffusion also is sufficient for intra-‐cellular gas distribution. Gas exchange in some thin, multi-‐cell, aquatic species -‐ Their gas exchange needs are satisfied by the diffusion of gas molecules across the cell membrane of each cell. o Every cell of the body contacts the surrounding water. Gas exchange in animals -‐ In many multi-‐cellular animals, most of their cells do not directly contact the surrounding air or water. o These animals require specialized respiratory organs to exchange gases effectively with the environment. The essential properties of gas exchange membranes -‐ They are highly folded or highly branched. o This significantly increases the surface area available for gas exchange by diffusion. -‐ They are thin and moist. -‐ Substances always diffuse from higher to lower concentration. -‐ Oxygen and carbon dioxide molecules can pass directly through the thin, moist membrane. All gas exchange membranes are ventilated -‐ Ventilation delivers air, or water, with high oxygen/ low carbon dioxide content to the environmental surface of gas exchange membranes. o Ventilation (breathing) creates the desired concentration gradients of oxygen and carbon dioxide across the gas exchange membrane in our lungs. All gas membranes are perfused -‐ Perfusion delivers circulatory fluid with high carbon dioxide/low oxygen content to the inner surface of gas exchange membranes. o Perfusion (blood flow) creates the desired concentration gradients of oxygen and carbon dioxide across the gas exchange membrane in our lungs. Respiratory system of animals -‐ The respiratory organs of animals (gills, lungs, skin, and trachea) must be-‐ o Ventilated o Perfused o Connected to the internal circulatory system. The tracheal system -‐ Insects have an internal system of inter-‐connected hollow tubes that enables gas exchange. o This highly branched system permeates the entire body. o Every cell in the body is adjacent to a tracheole (smallest air tube). o Tissues and organs with high metabolic demands are near the air sacs. The capillaries are the smallest blood vessels of the closed circulatory system -‐ They are specialized to enable the exchange of materials between the blood they contain and the surrounding fluid. Some aquatic animals have external gills. Some aquatic animals have internal gills -‐ Internal gills remove 80% of oxygen from water o The relative position of the gills and capillaries is specialized to enhance gas exchange. § There are always more oxygen molecules in the water flowing over the gills compared to the blood in the gill’s capillaries. Bird lungs are extremely efficient -‐ Air flow occurs in one direction only to ensure that only fresh air contacts the gas exchange surface. o Air with maximal oxygen concentration and minimal carbon dioxide concentration contacts the gas exchange surface of bird lungs. Human lungs -‐ Each human lung has a large surface area for gas exchange. o This is due to 250-‐300 million individual alveoli in each lung. § Each lung captures 25% of the oxygen molecules in inhaled air. -‐ There is a short distance between each alveolus and its surrounding capillaries. o This increases the rate of gas diffusion between the air in each alveolus and the blood in the surrounding capillaries. Breathing ventilates our lungs -‐ The diaphragm, external intercostal muscles, and internal intercostal muscles interact to change the volume, and thus the pressure, within the thoracic (chest) cavity. o Inhalation-‐ lung volume increases and pressure decreases. § The diaphragm and external intercostal muscles contract during inhalation. o Exhalation-‐ lung volume decreases and pressure increases. § Increased exhalation during exercise requires that the internal intercostal muscles contract. The breathing control centers of the brain -‐ The medulla oblongata and pons regions of the mid-‐brain regulate breathing. o They send nerve impulses through the phrenic and thoracic nerves that instruct the diaphragm and intercostal (rib) muscles to contract. -‐ Hormonal signals and nerve signals instruct the medulla oblongata and pons to adjust the rate of breathing in response to-‐ o Anxiety and fear o Altitude o Increased physical activity o Perception of danger o Temperature o Toxins GAS EXCHANGE IN FLOWERING PLANTS Plants must exchange gases with the environment -‐ Stomata are tightly regulated pores that enable leaves and green stems to exchange gases with the environment. o Carbon dioxide, oxygen, water and any other gas molecules present diffuse through the stomata from higher concentration to lower concentration. The precise regulation of stomata conserves water -‐ Guard cells turgid/stoma open o The stimuli that cause stomata to open are-‐ § Sunlight (blue light) § Low internal carbon dioxide concentration. -‐ Guard cells flaccid/stoma closed o The stimuli that cause stomata to close are-‐ § No blue light (no sunlight) § Disease § Low water availability (water stress) § High internal carbon dioxide concentration. Plants must exchange gases with the environment -‐ The bark that surrounds the organs (roots, stems) of woody plants is a gasproof, waterproof tissue called cork. -‐ Cork tissue contains loosely-‐packed, porous regions of cells called lenticels that enable-‐ o Oxygen uptake by diffusion o Carbon dioxide by diffusion. Gas molecules must be distributed within plant organs -‐ Gas molecules must diffuse within each plant organ in order to contact every cell in each organ. o The empty spaces within each plant organ enable oxygen and carbon dioxide molecules to diffuse through the interior of each organ. The submerged organs of aquatic plants require oxygen -‐ Lacunae are internal, hollow canals in the stems and roots of some aquatic plant species that are specialized to permit oxygen molecules to diffuse from the leaves to the submerged stems and roots. Gas diffusion among plant organs -‐ The porous aerenchyma tissue of gamma grass allows oxygen molecules to diffuse from the leaves to the roots so the roots can penetrate deeper, anaerobic, soil regions where water may be available. o Some wetlands plants have aerenchyma. INTERNAL TRANSPORT IN ANIMALS The medical consequences of insufficient circulation -‐ Amputation -‐ Heart attack -‐ Infarction (tissue death) -‐ Organ damage -‐ Stroke Angiogenesis is essential for tumor growth The circulatory system connects all of the body’s systems. Three components of every circulatory system -‐ A circulatory fluid (blood) -‐ A system of inter-‐connected tubes (blood vessels) -‐ One or more vascular pumps (heart) The artery system delivers blood under high pressure from the heart to the capillaries in the body’s tissues -‐ The artery wall is 2-‐3x thicker than the wall of a vein. -‐ Arterial blood is relatively high in oxygen and low in waste products. Vaso Vasorum, blood vessel of the blood vessel -‐ Larger blood vessels require smaller blood vessels to supply oxygen and nutrients to their smooth muscle tunica media. -‐ Vasa Vasorum means blood vessels of the blood vessels. o Small vessels located within larger vessels. The venous system delivers blood under low pressure from the body’s tissues to the heart -‐ The walls of veins are 2-‐3x thinner than the walls of arteries. -‐ Venous blood is lower in oxygen and higher in metabolic waste products compared to arterial blood. Moving blood through the venous system Capillaries permeate the body’s tissues -‐ Substances are exchanged between the blood in the capillaries and the surrounding tissue (interstitial) fluid. -‐ The rate of blood flow is reduced in the capillaries to promote the exchange of substances. Capillaries enable the exchange of substances -‐ Diffusion -‐ Bulk flow through pores and inter-‐cellular spaces. -‐ Endocytosis and exocytosis (transcytosis) -‐ White blood cells move through the extracellular spaces. Humans have a closed circulatory system -‐ Blood is confined to the blood vessels in a closed system. -‐ It enables the rapid redistribution of blood flow to-‐ o Increase blood flow to tissues with increased metabolic demands. o Decrease blood flow to tissues with reduced metabolic demands. -‐ Blood is continuously delivered to the-‐ o Brain o Heart o Kidneys o Liver -‐ Blood flow to the digestive system, lungs, skeletal muscles, and skin is adjusted to satisfy the body’s changing metabolic demands. Adjusting air flow to specific tissues -‐ The opening and closing of the precapillary sphincters is regulated to control blood flow to specific tissues. -‐ The vaso-‐dilation (nitric oxide) and vasoconstriction (endothelin) of the arterioles also control blood flow to specific tissues. o The body regulates the contraction of the smooth muscle surrounding the arterioles to adjust arteriole diameter and consequently control the flow of blood to specific tissues. The lymphatic system -‐ It returns the interstitial (tissue) fluid that exits the capillaries in the body’s tissues to the blood. o It is a system of inter-‐connected lymph vessels and lymphoid organs. o Lymph vessels possess valves to allow tissue fluid entry and also to prevent fluid backflow. o Lymph (the fluid in the lymph vessels) is propelled through the lymphatic system by muscles contraction and inhalation. Some parasitic worms infest the lymph vessels The heart is a remarkable, long-‐lived muscular pump The components of blood -‐ Serum is plasma without blood clothing factors.
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