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Chapter 26 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. 26-1 Coordination in Multicellular Animals Maintaining a constant internal environment is crucial for large multicellular organisms. – – 26-2 Accomplished by monitoring and modifying the functioning of various systems Called homeostasis Homeostasis maintains oxygen levels, blood pressure, heart rate, body temperature, fluid levels, pH, etc. Homeostasis is maintained by the nervous, endocrine and immune systems. Example: Running up a hill Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Negative Feedback Control 26-3 A common homeostatic mechanism Occurs when an increase in the stimulus results in a decrease in response Functions to maintain a set point Example: Thermostat Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Positive Feedback Regulation When an increase in stimulus results in an increase in response Does not result in homeostasis, but plays an important role in homeostasis – 26-4 Childbirth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nervous System Function 26-5 Important in making adjustments over a short time period Transmission of information is very fast in the nervous system. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Structure of the Nervous System Consists of a network of cells that carry information from one part of the body to another Made up of specialized cells called neurons – – – 26-6 Cell body or soma-contains the nucleus Dendrites-receive information and carry it to the cell body Axons-carry information away from the cell body Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Anatomy of a Neuron 26-7 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Central Nervous System 26-8 Brain and spinal cord Protected by skull and vertebrae Receives input from sensory organs Interprets and integrates information Generates responses Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Peripheral Nervous System Located outside the skull and vertebral column Consists of bundles of axons and dendrites called nerves – Somatic nervous system – Autonomic nervous system 26-9 Nerves that control the skeletal muscles Nerves that control the involuntary muscles, the heart and glands Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Types of Neurons Motor neurons – – Sensory neurons – – 26-10 Carry messages from the central nervous system to muscles and glands Usually have one long axon that runs from the spinal cord to the muscle or gland Carry input from sense organs to the central nervous system Have long dendrites that carry input from the sense organ to the brain or spinal cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Organization of the Nervous System 26-11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Nature of Nerve Impulses Information is transmitted through neurons in the form of nerve impulses. – – 26-12 Also known as action potentials Involve a sequence of chemical events at the cell membrane of the neuron Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neurons have an Unequal Distribution of Ions Inside and Outside of the Cell Active transport pumps sodium out and potassium in – – More sodium is pumped out than potassium pumped in As a result 26-13 Sodium is concentrated outside the cell. Potassium is concentrated inside the cell. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neurons have an Unequal Distribution of Ions Inside and Outside of the Cell This unequal distribution of charge generates a voltage across the neuronal cell membrane. – – – 26-14 Voltage is a measure of the electrical charge difference that exists between two points. The inside of the cell is more negative than the outside. At rest, the membrane voltage of a neuron is about -70mV. The voltage across the membrane makes it polarized. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Polarization of Cell Membranes 26-15 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Generation of a Nerve Impulse When a neuron is stimulated by an input … – – – – 26-16 The cell membrane becomes more permeable to sodium. Sodium ions enter the cell down their concentration gradient. The inside of the cell becomes more positive. The cell is depolarized. The depolarization spreads down the axon. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Generation of a Nerve Impulse Depolarization of any one segment of membrane is brief. – Repolarization is followed by the pumping of sodium out of and potassium into the cell. – – 26-17 Membrane becomes repolarized when potassium flows out of the cell This re-establishes the original concentration gradients. This brings the cell back to its resting membrane potential. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Nerve Impulse 26-18 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Activities at the Synapse The synapse is the small space between the axon of one neuron and the dendrite of another neuron. Neurons communicate with one another through the activities at the synapse. When the nerve impulse in one neuron reaches the synapse, chemicals are released from the end of the axon. – – – 26-19 Called neurotransmitters Diffuse across the synapse and bind to receptor sites on the dendrite of the other neuron This can cause depolarization and generate a nerve impulse in the second neuron. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Events at the Synapse 26-20 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neurotransmitters Made in the cell body and transported to the end of the axon to be stored until released. – Bind to receptors and stimulate them as long as they are bound Enzymes in the synapse destroy neurotransmitters, allowing the second cell to return to resting state. – 26-21 Acetylcholine was the first neurotransmitter identified. Acetylcholinesterase is the enzyme that breaks down acetylcholine. Many drugs interfere with neurotransmission at the synapse. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Direction of Information Flow Information in the nervous system only travels in one direction… – – – 26-22 From the axon of one cell to the dendrite of another in a synapse From the dendrites to the cell body of one neuron From the cell body through the axon to the synapse Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Organization of the Central Nervous System The brain consists of several different regions that have specific functions. The functions of the brain can be divided into three major levels. – – – 26-23 Automatic activities Basic decision making and emotions Thinking and reasoning Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Organization of the Central Nervous System Spinal cord – – Collection of neurons and nerve fibers surrounded by the vertebrae Conveys information to and from the brain Medulla oblongata – – The base of the brain where the spinal cord enters the brain Controls fundamental life support activities such as – Fibers from the spinal cord cross sides in the medulla 26-24 Blood pressure Breathing Heart rate Right side of body is controlled by left side of brain and vice versa Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Organization of the Central Nervous System Cerebellum – – – Large bulge at the base of the brain Connected to the medulla oblongata Receives information from sensory organs that involve balance – 26-25 Inner ear, eyes, pressure sensors in muscles and tendons Regulates muscle activity to establish balance and coordination Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Organization of the Central Nervous System Pons – – The region of the brain that is anterior to the medulla oblongata Controls many sensory and motor functions of the head and face Thalamus – – Located between the pons and the cerebrum Relays information between the cerebrum and the lower centers of the brain – – 26-26 Spinal cord, medulla, pons Important in awareness Involved in sleep and arousal Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Organization of the Central Nervous System Hypothalamus – – Involved in sleep and arousal Important in emotions – – Regulates body temperature, blood pressure and blood volume Connected to and controls the pituitary gland 26-27 Fear, anger, pleasure, hunger, sexual responses, pain Controls the release of hormones Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Functions of More Primitive Brain Regions 26-28 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Organization of the Central Nervous System Cerebrum – – – – – 26-29 The thinking part of the brain. Comprised of two hemispheres Controls memory, language, movement Responsible for the integration of sensory input The major site of association and cognition. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Specialized Areas of the Cerebrum 26-30 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endocrine System The Endocrine system – Hormones – A collection of glands that communicate with one another and with body tissues through the release of hormones. Chemical signals released by one organ that are transported to another organ where it triggers a change in activity Glands – – Organs that make and release specific chemicals Endocrine glands – Exocrine glands 26-31 Lack ducts Secrete hormones in to the circulatory system Have ducts Release their products into the digestive tract or onto the skin Digestive glands, sweat glands Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endocrine Glands 26-32 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endocrine System Function Hormones released by endocrine glands travel throughout the entire body. – Target cells respond by – – – 26-33 However, they only bind to and affect target cells that have receptors. Releasing products that have been previously made Making new molecules or increasing metabolic activity Dividing and growing Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Some Examples of Hormone Action Epinephrine and norepinephrine – – Released by the adrenal medulla during emergency situations Acts quickly Antidiuretic hormone – – Released from posterior pituitary in response to dehydration Acts more slowly 26-34 Increases heart rate, blood pressure and breathing rate Shunts blood to muscles Targets kidney cells Increases the re-absorption of water Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Some Examples of Hormone Action Insulin – – – – Works rapidly Produced and released from the pancreas Stimulates cells to take in glucose Is released in response to high glucose levels in the blood – Diabetes is a lack of insulin Cells don’t take in glucose Growth-stimulating hormone – – – 26-35 Would occur after a high carbohydrate meal Works over a period of several years during childhood Produced by the anterior pituitary Stimulates growth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Integration of Nervous System and Endocrine System Function The pituitary gland links the endocrine system to the nervous system. – – Located at the base of the brain Divided into two parts Anterior pituitary – An endocrine gland – Produces hormones that trigger other glands to release their hormones – Receives commands from the chemicals released from the hypothalamus Posterior pituitary – Part of the brain – Holds the axons from cells in the hypothalamus – Releases specific hormones into the bloodstream 26-36 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hormones of the Pituitary 26-37 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Integration of Nervous System and Endocrine System Function Example: In songbirds, the length of day causes hormonal changes that prepare the animals for reproduction. – – – – – 26-38 Length of day is sensed by the pineal body in the brain. The pineal gland controls the release of chemicals from the hypothalamus. The chemicals released by the hypothalamus trigger the pituitary to release hormones into the bloodstream. These pituitary hormones stimulate the reproductive organs to secrete reproductive hormones. These reproductive hormones trigger courtship and mating rituals in birds. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Interaction Between the Endocrine and Nervous Systems 26-39 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sensory Input The nervous and endocrine systems respond to sensory input. – – This input comes from sense organs. Some sense organs detect external stimuli. – Other sense organs detect internal stimuli. 26-40 Vision, hearing, touch Pain and pressure The sense organs detect changes; the brain is responsible for perception. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chemical Detection All neurons have chemical receptors on their surface. – – Other types of cells have chemical receptors as well. – 26-41 When chemicals bind to these receptors, the activity of the cell changes. Usually results in depolarization and the generation of a nerve impulse. The aorta can sense and respond to changes in hydrogen ions, carbon dioxide and oxygen in the blood. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Taste Taste buds are sensory cells located on the tongue. They have chemical receptors that respond to classes of molecules. These classes correspond with the five kinds of taste we experience. – 26-42 Sweet, sour, salt, bitter and umami (meaty) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Taste Sour and salty sensation results from ions entering taste buds and causing a depolarization. – – Sweet, bitter and umami sensations result from molecules binding to receptors on taste buds. – – 26-43 Sour sensing taste buds respond to hydrogen ions. Salty sensing taste buds respond to sodium chloride. Sweet receptors are stimulated by sugars, artificial sweeteners, etc. Umami receptors are stimulated by glutamate. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Smell The sensory receptors in the nose are more versatile than taste buds. – – – – 26-44 They can sense thousands of different molecules at low concentrations. Found in the olfactory epithelium Very sensitive Fatigue quickly Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Vision The sensory cells in the eyes respond to changes in the flow of light energy. Light-sensing cells are found in the retina. – – Light-sensing cells are called rods and cones. – – 26-45 At the back of the eye The other parts of the eye are designed to focus light onto the retina – Rods are very sensitive and can detect dim light but not color. Cones are less sensitive, but can detect different wavelengths of light (color). This is why we cannot see color at night. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Structure of the Eye 26-46 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Vision The fovea centralis is a region in the retina with many cones and no rods. – Rods and cones sense light because they contain pigment molecules. – – – – 26-47 This area gives us the most focused and detailed vision. Rhodopsin is the pigment in rods. When light hits rhodopsin, it changes shape and causes the rod to depolarize. This generates a nerve impulse that is sent to the brain. Different types of cones have different pigments that respond to specific wavelengths of light. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Light Reception by Cones 26-48 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hearing and Balance One set of sensory cells in the ear responds to changes in sound waves. – – These sensory cells are found in the cochlea. Sound is produced by the vibration of molecules. The other set of sensory cells in the ear responds to movements of the head. – – These cells are found in the fluid-filled semi-circular canals. They sense the position of the head with respect to the force of gravity. 26-49 Volume is a measure of the intensity of the vibration. Pitch is determined by the frequency of the vibration. Helps maintain balance Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Anatomy of the Ear 26-50 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hearing The ear is designed to funnel sound and transmit the vibrations to the sensory cells. – – – – – 26-51 External ear funnels sound to the eardrum. The eardrum (tympanic membrane) vibrates in response to sound. The vibration is passed to small bones (malleus, incus and stapes) in the middle ear. The bones, in turn, vibrate another membrane covering the oval window. The oval window is an opening into the cochlea. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hearing 26-52 The cochlea is a tube filled with fluid under pressure. When the oval window vibrates, the fluid in the cochlea vibrates. This vibration causes the basilar membrane to vibrate. Sensory cells on the basilar membrane are depolarized when it vibrates. The depolarization generates a nerve impulse that is transmitted to the brain. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Touch Sensory receptors in the skin and internal organs respond to changes in pressure and temperature. – Found all over the body, but more concentrated in certain areas Pain receptors in the skin and internal organs respond to cell damage and extreme pressure and temperature. – 26-53 Tips of fingers, genitalia, lips, etc. That is why these areas are the most sensitive to touch. Allows our brain to monitor our internal activities Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Output Coordination After sensing changes in the external or internal environments, – Responses may involve – – 26-54 The nervous and endocrine systems work together to cause a change in response. Muscle contraction Hormone secretion by glands Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Muscles Muscle contraction facilitates movement. Muscles pull by contracting. – – Muscles exist in antagonistic sets. – – – 26-55 But, they do not push by lengthening. Relaxation is merely passive. The biceps cause the arm to bend. The triceps cause the arm to extend. Biceps and triceps are antagonistic muscles. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Antagonistic Muscles 26-56 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Muscular Contraction A muscle is made up of many muscle cells. Muscle cells are made up of many myofibrils. Myofibrils are bundles of fibers made up of myofilaments. – – 26-57 When these fibers move past one another, the muscle contracts. This movement requires the energy from ATP. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Myofilaments and Contraction Myofilaments are either thick or thin. – Thick filaments are made of myosin. – Shaped like a golf club The head of the ‘golf club’ is positioned to bind to the thin filaments. Thin filaments are made of actin, tropomyosin and troponin. Actin filaments are shaped like two pearl necklaces intertwined. Tropomyosin and troponin are shaped like a gold thread that is laid on the pearl necklace. – 26-58 These molecules block actin and prevent the interaction between actin and myosin. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Events of Muscle Contraction 26-59 The nerve impulse arrives at the muscle cell. The muscle cell depolarizes. Calcium ions are released onto the myofibrils. The calcium ions bind to troponin, causing the troponin-tropomyosin complex to move. This exposes actin, allowing myosin and actin to interact. Myosin heads bind to actin, the heads flex, pulling actin. This causes the muscle cell to shorten (contract). Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Interaction Between Actin and Myosin 26-60 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Types of Muscles There are three types of muscles: – Skeletal – Smooth – Mediate involuntary movement Digestive tract, reproductive tract Cardiac 26-61 Mediate voluntary movement Arms, legs, neck, back, abdomen, lungs Heart muscle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Skeletal Muscles Voluntary muscle Controlled by the brain – – 26-62 Brain sends the command to the spinal cord Spinal cord sends the command to the muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Skeletal Muscles Many neurons from the spinal cord end in each muscle. – Each neuron stimulates a specific set of muscle cells called a motor unit. – – – 26-63 A motor unit is one neuron and all of the muscle cells it stimulates to contract. Each muscle has many motor units. This allows for different intensities of contraction in one muscle. The intensity of contraction is dependent on how many motor units are stimulated at once. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Skeletal Muscles Skeletal muscle cells contract quickly, but fatigue quickly. – 26-64 Different motor units must be recruited to keep a muscle contracted for a long time. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Motor Units 26-65 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Smooth Muscles Found in the muscular walls surrounding internal organs Contract in response to being stretched – Digestive system Involuntary – – Do not need direct messages from nervous system Some respond to hormones 26-66 Is constantly stretched as food passes through The responsive contractions result in rhythmic movements that move food through Uterine contractions in response to oxytocin Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cardiac Muscle Makes up the heart Can contract rapidly without direct nervous system stimulation The rate of contraction can be controlled by – – Cannot stay contracted for a long time – 26-67 The nervous system Hormones (epinephrine and norepinephrine) Must relax between contractions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Characteristics of Different Kinds of Muscles 26-68 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Activities of Glands There are two types of glands. – Endocrine glands – Exocrine glands 26-69 Secrete hormones into the bloodstream Pituitary, thyroid, ovary, testes, etc. Secrete substances to the surface of the body or into the tubular organs (gut, reproductive tract) Salivary glands, intestinal mucus glands, sweat glands, etc. Some are controlled by the nervous system (salivary). Some are controlled by hormones (digestive). Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Growth Responses Hormones regulate growth. – – Growth-stimulating hormone is produced throughout childhood to increase the size of the body. Testosterone released during puberty in males stimulates Bone and muscle growth – – Growth of the penis, larynx and hair on face and body Estrogen released during puberty in females stimulates 26-70 This is why men are generally taller and more muscular than women. Growth of reproductive organs Development of breast tissue Start of the menstrual cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Body’s Defense Mechanisms Immunity is the ability to maintain homeostasis by resisting or defending against potentially harmful agents. – The immune system is made up of specialized cells and molecules that fight infection and disease. – – – 26-71 Microbes, toxins, tumor cells, etc. Generates nonspecific and specific defenses Nonspecific defenses protect the body from a lot of things. Specific defenses recognize specific threats and attack them in specialized ways. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nonspecific Defenses 26-72 General ways that the body prevents disease and infection No previous contact with the danger is required. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nonspecific Defenses Defensive barriers – – – – Chemicals – – Skin and mucous membranes Block the entry of pathogens Lysozyme, found in skin, destroys bacterial cells. Mucus traps pathogens so that they can be eliminated. Complement proteins circulate in the blood and help immune cells attack and kill pathogens. Interferons are proteins that prevent viruses from attaching to and entering cells. Certain types of cells – Cells and chemicals interact to mediate inflammation. 26-73 A series of events that clears a damaged area of harmful agents and damaged tissue Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inflammation 26-74 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Specific Defenses These mechanisms must be turned on by a primary exposure to the harmful agent. – The harmful agent that causes a response is called an antigen. – – – – Usually a large protein Stimulates the production of a specific defense mechanism Becomes neutralized or destroyed by that mechanism Can be toxins or parts of viruses or bacterial cells T-lymphocytes and B-lymphocytes respond to antigens. – – 26-75 Therefore, it is called “acquired immunity”. Each type of lymphocyte works a little bit differently. Each are needed for specific immunity to work correctly. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. B-cell and Antibody Mediated Immunity B-lymphocytes (B-cells) are made in bone marrow. – When a B-cell contacts an antigen – – – 26-76 Found mostly in lymph nodes and spleen Information is sent to the nucleus and genes are activated. This results in an antibody being made that is specific to that antigen. The antibody will be released by the B-cell and will bind to the antigen, making it a target for destruction. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Classes of Antibodies 26-77 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. B-cell and Antibody Mediated Immunity After antigen binding, that B-cell will only make that specific antibody. – – – – 26-78 It has been activated. All of their descendants will only produce that antibody. Some descendants will be plasma cells that make and release antibodies. Some descendants will be memory cells. During the infection/danger, plasma cells outnumber memory cells. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. B-cell and Antibody Mediated Immunity After the infection/danger, plasma cell number drops; but memory cells remain. When the same antigen appears again – – 26-79 The memory B-cells produce more plasma cells very rapidly. The plasma cells make and release antibody that leads to the elimination of the threat. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Immunization A technique to induce an acquired immune response Utilizes vaccines to expose the body to an antigen without causing an infection – – 26-80 Usually contains pieces of the bacteria or virus Some are synthetic, with molecules that mimic the real antigen. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Immunization When the vaccine is given, the B-cells react as described. – – When the real antigen is encountered again (during infection) – – 26-81 This is called a primary immune response. Generates memory B cells The memory B cells generate a swift, massive response. Eliminates the infection before illness sets in Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Active Immunity due to Immunization 26-82 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. T-cell and Cell-mediated Immunity T-lymphocytes (T-cells) are made in bone marrow. – – – – 26-83 Mature in thymus Found in blood, lymph and lymph tissue Regulate B-cell activity Rupture pathogens, virus-infected cells and cancer cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Becoming a Specialized T cell 26-84 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Activating T-cells T-cells only become active if the pathogen is “presented” to it by other cells. – – – – 26-85 Called antigen presenting cells (APCs) These are macrophages that have ingested the pathogen. They break the pathogen into pieces and send the pieces to their cell surface. The APCs then present the antigen to the T-cells. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Activating T-cells When the T-cell detects the antigen, a signal is sent to the nucleus, DNA is altered and the cell becomes differentiated into one of three forms. – – – 26-86 T-regulator cells Cytotoxic T-cells T-memory cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Types of T-cells T-regulator cells – – Communicate with B-cells and help them control the amount of antibody produced Two types of T-regulator cells 26-87 T-helper cells encourage B-cells to make antibodies. T-suppressor cells inhibit B-cells from making antibodies. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Types of T-cells Cytotoxic T-cells – – – T-memory cells – 26-88 Move toward the pathogen and make holes in it Target bacteria, cancer cells, transplanted cells, parasites Release cytokines, chemicals that attract WBCs to the site of infection Remember specific antigens so that a faster response can be initiated upon repeated exposure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Allergic Reactions An allergy is an abnormal immune reaction to an antigen. – If the antigen comes from outside the body, it is called an allergen. – 26-89 Food, pollen, drugs Involves an interaction between the antigen and a B-cell antibody Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Allergic Reactions Type I hypersensitivity – – – Associated with an antibody called IgE Upon first exposure, the allergen stimulates a B-cell to make IgE. Upon second exposure to the allergen, the B-cells make a lot of IgE. 26-90 IgE stimulates the release of histamine, leukotrienes and prostaglandins. These chemicals cause skin rashes, hives, asthma, eczema, headaches, etc. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Allergic Reactions Anaphylactic shock – – – 26-91 The most severe allergic reaction Starts with reddening of the skin and progresses through a severe drop in blood pressure and can lead to death. Epinephrine will block the progression of anaphylactic shock. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. How an IgE Allergy Works 26-92 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Autoimmune and Immunodeficiency Diseases Autoimmune diseases result from the immune system turning against normal cells or molecules in one’s body. – – – Immunodeficiency disease results when one or more components of the immune system do not work properly. – – 26-93 The immune system attacks and kills normal, healthy cells. Rheumatoid arthritis - normal cartilage is attacked. Type I diabetes - cells that make insulin are attacked. – Makes people more susceptible to infections and cancers. SCIDS - a genetic immunodeficiency disease AIDS - a viral-induced immunodeficiency disease Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.