Exam #3 Study Guide
Exam #3 Study Guide ASCI 141
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This 40 page Study Guide was uploaded by Katarina Fielding on Monday April 11, 2016. The Study Guide belongs to ASCI 141 at University of Vermont taught by Feng-Qi Zhao in Spring 2016. Since its upload, it has received 49 views. For similar materials see Anatomy and Physiology of Domestic Animals in Animal Science and Zoology at University of Vermont.
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EXAM #3 STUDY GUIDE CHAPTER #8- MUSCULAR SYSTEM INTRODUCTION FEATURE SKELETAL CARDIAC SMOOTH MUSCLE MUSCLE MUSCLE LOCATION SKELETAL HEART INTERNAL MUSCLES ORGANS, BLOOD VESSELS, EYES ACTION MOVE THE BONES, PUMP BLOOD PRODUCE GENERATE HEAT MOVEMENTS IN INTERNAL ORGANS AND STRUCTURES NUCLEI MULTIPLE SINGLE SINGLE STRIATIONS PRESENT PRESENT ABSENT CELL SHAPE LONG, THIN BRANCHED SPINDLE FIBERS NERVE SUPPLY NECESSARY FOR MODIFIES VISCERAL- FUNCTION ACTIVITY, NOT MODIFIES NECESSARY FOR ACTIVITY, NOT FUNCTION; MULTI- NECESSARY FOR UNIT NECESSARY FUNCTION FOR FUNCTION CONTROL VOLUNTARY INVOLUNTARY INVOLUNTARY SKELETAL MUSCLE Moves the bones of the skeleton- used to be called voluntary striated muscle Striations- alternating, crosswise, dark and light bands running the length of each cell o GROSS ANATOMY OF SKELETAL MUSCLE Well defined group of muscles cells surrounded by a fibrous connective sheath called the epimysium Come in a variety of shapes and sizes nut usually have a thick central portion (belly) and two or more attachment sites that join them to whatever structures they move when they contract o SKELETAL MUSCLE ATTACHMENTS Most attached to bones at both ends by tendons- tough, fibrous connective tissue bands; continuations of the epimysium If not attached by tendons, some muscles are attached to bones or other muscles by aponeuroses- broad sheets of fibrous connective tissue- most common one is the linea alba More stable muscle attachment site- origin of the muscle –does not move much when the muscle contracts Muscle attachment site which undergoes most of the movement when the muscle contracts - insertion o SKELETAL MUSCLE ACTIONS agonist- ( prime mover)- muscle or muscle group that directly produces a desired movement Antagonist- muscle or muscle group that directly opposes the action of an agonist In partially contracting, antagonists can help smooth out the movements of agonists or can contract forcefully at the same time resulting in rigidity and lack of motion Synergist- skeletal muscle that contracts at the same time as an agonist and assists it in carrying out its action Fixator muscles- stabilize joints to allow other movements to take place o MUSCLE-NAMING CONVENTIONS Often names of physical characteristics: Action: portion of a muscle’s name is often related to its function; muscles that flex a joint are often called flexor muscles; extensor muscles do opposite in extending the joints Shape: muscle’s name can reflect its distinctive shape; ex. deltoid- means triangle shaped, deltoid is a triangle shaped muscle in shoulder region Location: muscle’s name can indicate a physical location in the body; ex. biceps brachii- located in the brachial region of the arm Direction of fibers: rectus= straight, abdominis rectus- the fibers of the muscle run straight with the long axis of the body and parallel to each other Number of head or divisions: number of heads= number of attachment sites that the muscle has to its origin- cephal means head; biceps brachii= 2 heads, triceps brachii= 3 heads, quadriceps femoris= four heads o SELECTED SKELETAL MUSCLES CUTANEOUS MUSCLES Cutaneous muscles are the skin muscles; not directly in the skin but in the connective tissues aka fascia directly underneath it; have little to no bone attachment unlike many other skeletal muscles; thin, broad, superficial and serve only to twitch the skin HEAD AND SKELETAL MUSCLES Control facial expression, enable chewing, and move sensory structures such as eyes and ears Neck muscles help support the head and allow the neck to flex, extend, and move head laterally Large masseter muscle in the cheek area of the skull is the most powerful of chewing muscles: main action is to close the jaw Splenius and trapezius muscles raise/extend the head and neck Brachiocephalicus- extends head and neck and flexes front of the leg; reaches from the base of skull to the proximal end of the humerus Neck flexor muscles located on the lower portion of the neck; sternocephalicus muscle- smaller and strap like which extends from sternum to the base of skull and helps to flex/lower the head or neck Flexors do not have to be very large because gravity helps ADOMINAL SKELETAL MUSCLES Function to support the abdominal organs but also help to flex (arch) the back and participate in various functions that involve straining, such as expulsion of feces from the rectum, urine from the bladder, a fetus from the uterus, and the processes of vomiting and regurgitation, also play a role in respiration Arranged in layers: from the outside in- external oblique, internal oblique, rectus abdominis, and the transverse abdominis; left and right parts of the muscles come together on ventral midline of the linea alba; oblique muscles named that ways because their muscle fibers run in a slanting direction to the long axis of the body and opposite to each other; external oblique run in a backward and downward direction while the internal runs forward and downward Rectus abdominis makes the wall of the abdominal cavity and consist of two strap like muscles on either side of the linea alba that runs from the ribs and sternum to the brim of the pubis Transversus abdominis- deepest and the fibers run directly downward in a ventral direction to insert on the linea alba THORACIC LIMB SKELETAL MUSCLES Function mainly in locomotion thereby allowing the animal to walk and run and generally move around in its environment Superficial muscles of the shoulder: latissimus dorsi- broad, triangular muscle that extends from the spinal column down to the insertion of the humerus- flexes the shoulder Two pectoral muscles one deep and one superficial- located on each side of the sternum, both extend from humerus to sternum and act as adductor (inward moving) muscles of the front leg- help keep the front legs under the animal and prevent them from splaying out to the sides Deltoid muscle is a abductor (outward mover) muscle and flexes the shoulder joint Biceps brachii and triceps brachii- both part of the brachium regions and have opposite action on the elbow joint- biceps brachii= two proximal head attachments, extends from distal end of the scapula to the proximal end of the radius- in contracting, flexes the elbow joint; triceps brachii- three proximal head attachments and extends from the distal scapula and proximal humerus to the olecranon process of the ulna- contracting causes the extending of the elbow joint Muscles distal to the elbow joint- collection of carpal and distal flexors and extensors which play important roles in locomotion; their precise locations, names, and actions vary greatly PELVIC LIMB SKELETAL MUSCLES Large gluteal muscles and the hamstring muscle groups are extensors of the hip joint- help propel the body forward by extending the hip joint The gluteal muscles extend from the bones of the pelvis down to the trochanters of the femur Hamstring muscle group is three muscles located on the caudal part of the thigh region: biceps femoris, semimembranosis, and semitendinosis- not only help to extend the hip joint but are also the main flexors of the stifle joint Quadriceps femoris- main extensor muscle of the stifle joint- located in the cranial part of the thigh region, composed of four heads Gastrocnemius- equivalent to our main calf muscle; extends from the caudal portion of the distal end of the femur and inserts on the calcaneal tuberosity of the fibular tarsal bone; distal gastrocnemius tendon in humans is the Achilles tendon and attaches to the heel; powerful extensor muscle of the hock; helps propel the body forward as an animal takes a stride SKELETAL MUSCLES OF RESPIRATION Increase and decrease the size of the thoracic cavity to draw air into and push air out of the lungs Drawing air into the lungs= inspiration; muscles which increase the size of the thoracic cavity when they contract are the inspiratory muscles Pushing air out of the lungs= expiration; muscles that decrease the thoracic cavity size are expiratory muscles Main inspiratory muscles are the diaphragm and the external intercostal muscles; diaphragm is thin, dome shaped sheet of skeletal muscles which separates the abdominal and thoracic cavity; external intercostal muscles have fibers which are directed in an oblique direction Expiration does not require as much effort as inspiration because the mechanical forces such as gravity and the elastic nature of the lungs help collapse the rib cage and push air out- internal intercostal muscles and the abdominal muscles help with this o MICROSCOPIC ANATOMY OF SKELETAL MUSCLES SKELETAL MUSCLE CELLS Large cells- not very wide but they are long cells- can be several inches long while normal body cells are a few micrometers, very thin despite being very long and gives them and overall threadlike or fiber like shape, usually fibers instead of cells Skeletal muscle fibers have more than one nucleus; and large fibers can have 100 or more nuclei per cell which are all located out at the edge of the cell just beneath the sarcolemma Most of the volume of one muscle cell is made up of hundreds or thousands of smaller myofibrils packed together lengthwise; the prominent organelles between the myofibrils include many energy-producing mitochondria, an extensive network of sarcoplasmic reticulum (storage organelle for calcium ions) and transverse (T) tubules which extend in from the sarcolemma Each myofibril helps to make up the contractile units which are called sarcomere, z line at the end of each sarcomere and they are shared by adjacent sarcomeres Thin protein filaments are called actin and attach to the z lines and extend towards the center of the sarcomere but do not meet; thick protein filaments are called myosin and appear to float in the middle of the sarcomere between parallel actin fibers and they do not connect to Z lines I bands are made up of thin actin filaments and extend from one end of thick myosin filament in one sarcomere across the Z line to the beginning of the myosin fibers in the next sarcomere; in center of I band is the z line which is the attachment for the actin filaments; from one Z line to the next Z line is one sarcomere Between the I bands are the A bands- areas where the thick myosin filaments and thin actin filaments overlap H band is light colored area located in the middle of the A band, it is made up of the myosin filaments only so it doesn’t cover the entire width of the myosin filament Myosin filaments don’t extend all the way from one Z line to the next; part of the I band between the end of the A band and the Z line; I band crosses the Z line and continues until it comes to the beginning of the next myosin filament, where the A band begins again Actin fibers- two strands of protein twisted together to form a helical structure similar in appearance to a DNA molecule; myosin molecule has a twisted tail attached to two globular heads that form cross-bridges to actin and interact with the actin to shorten the sarcomere during muscle contraction NEUROMUSCULAR JUNCTION Unless the skeletal muscle does not receive nerve impulses then they do not do anything Atrophy happens when the muscle’s nerve supply is interrupted for a lengthy period of time as a result of injury lacking the ability to function and also shrinking down in size Ends where the motor nerve fibers connect to muscle fibers are called neuromuscular junctions Synaptic space- located between the end of the nerve fiber and the sarcolemma of the muscle fiber; synaptic vesicles that contain the chemical neurotransmitter acetylcholine nerve impulse coming down the muscle fiber causes the release of acetylcholine and which crosses the synaptic space and binds to receptors on the sarcolemma which starts the process of contraction, if the muscle needs to contract another time, another nerve impulse needs to be sent Each nerve fiber send impulses to more than one muscle fiber, number of muscle fibers per nerve fiber determines how small a movement will result from a nerve stimulus; motor unit- used to describe one nerve fiber and all the muscle fibers it innervates Muscle fibers that make very small, delicate movements and have only a few muscle fibers per nerve fiber in each motor unit Large, powerful muscles may have a hundred or more muscle fibers per motor unit, allows the nervous system to control the activities of skeletal muscles in an economical manner CONNECTIVE TISSUE LAYERS Endomysium- delicate connective tissue layer which surrounds each individual skeletal muscle fiber- composed of fine, reticular fibers Groups of skeletal muscle fibers called fascicles are bound together by a tougher connective tissue layer called perimysium which is composed of reticular fibers and thick collagen fibers Epimysium- surrounds a groups of muscles fascicles which is fibrous connective tissue layer composed largely of tough collagen fibers, outer covering of the entire muscle These connective tissue layers are continuous with the tendon and aponeuroses that connect the muscle to bones or other muscles; hold components of the muscle together and also help fasten the muscle firmly to its attachment mechanisms, also contain the blood vessels and nerve fibers that supply the muscle fibers, commonly contain varying amounts of fat Marbling- fat deposits are often grossly visible in meat o PHYSIOLOGY OF SKELETAL MUSCLE INITIATION OF MUSCLE CONTRACTION AND RELAXATION Impulses reaches he sarcoplasmic reticulum and causes the release of calcium ions into the sarcoplasm, calcium ions diffuses into the myofibrils and turns on the contraction process which is powered by ATP As soon as the sarcoplasmic reticulum releases the calcium ions into the sarcoplasm it begins pumping it back in and then pulls the calcium ions out of the myofibrils and the contraction process shuts down Amount of calcium in the muscle fiber is determined largely by the level of the calcium in the bloodstream; if blood calcium level is too high or too low, abnormalities in the skeletal muscle function can result MECHANICS OF MUSCLE CONTRACTION When muscle fiber is in a relaxed state, actin and myosin filaments overlap only a little; when stimulated to contract, globular heads attached to the tails of myosin filaments which are in contact with the actin filaments ratchet back and forth and pull the actin filament on both sides towards the center of the myosin filaments Combined shortening of the all the end to end sarcomeres in a muscle fiber results in muscle contraction; the H band becomes shorter and the A band becomes wider CHARACTERISTICS OF MUSCLE CONTRACTION All-or-nothing principle- an individual muscle fiber either contracts completely when it receives a nerve impulses, or it does not contract at all; body produces movements that vary in range and strength by carefully controlling the number of the muscle fibers it stimulates for a particular movement Small fine movements only require few muscle fibers to contract while the larger, more powerful movements require the contraction of many muscle fibers; nervous system is called the “shots”: must determine how large and powerful a movement needs to be and then it must send the appropriate nerve impulses down the appropriate muscle fibers in the appropriate muscle(s) Single muscle contraction – known as a twitch contraction: divided into three phases o The latent phase- brief hesitation between the nerve stimulus and the beginning of the actual contraction; lasts about 10 milliseconds o The contracting phase- lasts about 40 milliseconds o The relaxation phase- lasts about 50 milliseconds Entire contraction cycle lasts about 100 milliseconds Muscles rarely contract by twitching; do so mainly by careful timing of nerve impulses to the various motor units of the muscle; twitches are stimulated out of phase with each other so they occur at slightly different times CHEMISTRY OF MUSCLE CONTRACTION ATP is produced by many mitochondria in muscle fibers and controls the sliding of the actin and myosin fibers; ATP has 3 phosphate molecules and when one phosphate molecule is released forming ADP, a considerable amount of energy is released which powers the sliding of the myosin and actin filaments; this discharges the ATP molecule and requires something to recharge it: creatine phosphate (CP molecule) converts ADP back into ATP CP molecule splits and the energy released adds the phosphate group to the ADP and converts it to ATP; ultimate energy source producing ATP and CP and keeping the whole system operating comes from the breaking down (catabolism) of nutrient molecules: two main compounds are glucose and oxygen: glucose primary energy source for most body cells including muscle cells: muscles have very large blood supply which constantly brings new supplies of glucose and oxygen to the muscle fibers Glucose is stored in muscle fibers in the form of glycogen and oxygen is stored attached to the protein myoglobin; in terms of oxygen supply; if it is adequate to keep up with the energy needs of the fiber, process isknown as aerobic (oxygen consuming) metabolism where maximum amount of energy is extracted from each glucose molecule Sometimes during strenuous activity the need for oxygen exceeds the supply of oxygen and the muscle fibers must turn to anaerobic metabolism; it is not as efficient as aerobic metabolism and results in lactic acid formation as a byproduct of incomplete glucose breakdown HEAT PRODUCTION Considerable amount of energy produced in muscles is in the form of heat; muscular activity is one of the major heat generating mechanisms that the body uses to maintain a constant internal temperature Excess heat s releases by panting or sweating while if there is too little heat small spasmodic muscle contractions known as shivering occurs CARDIAC MUSCLE o GROSS ANATOMY OF CARDIAC MUSCLE Known as involuntary striated muscles; contractions are not under conscious control, striated look under the microscope similar to skeletal muscle Only found in the heart and forms most of the volume of the heart and makes up the majority of the walls of the cardiac chambers Cardiac muscle cells form elaborate networks around the cardiac chambers; arrangement and physical characteristics of cardiac muscles allow it to start contracting early in the embryonic period and does not rest until the animal dies o MICROSCOPIC ANATOMY OF CARDIAC MUSCLE Striated like skeletal muscle cells, and contain many of the same organelles and intracellular structures such as myofibrils but otherwise they are very different Cardiac muscle cells are much smaller than skeletal muscle cells and have only one nucleus per cell; longer rather than wide and often have multiple branches; securely attached to each other end to end to form intricate, branching network of cells Attachments between muscle cells are called intercalated discs and securely fasten the cells together and also transmit impulses from cell to cell to allow large groups of cardiac muscle cells around the cardiac chambers function as if they were each a single large unit instead of a whole bunch of individual cells o PHYSIOLOGY OF CARDIAC MUSCLE MUSCLE CONTRACTIONS Each cell contracts rhythmically with no external stimulation and each cell would be contracting at a constant rate set by the internal metronome; if two cell touch then the slower contracting cell adopts the faster cell’s contraction rate o Contracts without any external stimulation o Groups of cardiac muscle cells adopt the contraction rate of the most rapid cell in the group- self-starting and self-controlling aspects of cardiac muscle enable the heart to function as a very efficient pump Cardiac muscle contracts in a rapid, wavelike fashion which effectively squeeze blood out of the cardiac chambers; for the contractions of cardiac muscle to move blood effectively through the chambers and valves of the heart and out to the rest of the body so they must be carefully initiated and controlled The impulse that starts each heartbeat starts in the heart’s “pacemaker”, the sinoatrial (SA) node located in the wall of the right atrium, contraction rate of the cells in the SA node is faster than those in the walls of the atria or ventricles and therefore takes precedence; follows a carefully controlled path through the conduction system of the heart NERVE SUPPLY Heart does have a nerve supply that can modify its activity as it does not need it to initiate; nerves in the heart are from both the sympathetic and parasympathetic system; sympathetic fibers stimulate the heart to beat harder and faster as part of the fight or flight response; parasympathetic fibers do the opposite in that they inhibit cardiac function thereby causing the heart to beat more slowly and with less force when the body is relaxed and resting; two opposing systems strike a balance which keeps the heart’s function where it should be at SMOOTH MUSCLE o GROSS ANATOMY OF SMOOTH MUSCLE Nonstriated involuntary muscle; involuntary because its contractions aren’t under conscious control, smooth part because they do not have striated muscle Found all over the body but not in distinct structures; found in two forms: a large sheets of cells in the walls of some hollow organs (visceral smooth muscle) and as a small discrete group of cells (multiunit smooth muscle) o MICROSCOPIC ANATOMY OF SMOOTH MUSCLE Small and spindle shaped with a single nucleus in the center; smooth homogenous appearance under the microscope because actin and myosin filaments are not arranged as parallel Crisscross the cell at various angles and are attached at both ends to dense bodies that correspond to the Z lines of skeletal muscles o PHYSIOLOGY OF SMOOTH MUSCLE VISCERAL SMOOTH MUSCLE Found in the walls of internal soft organs which are known by viscera; linked to form large sheets in the walls of organs; fine movements are not possible, instead undergo large, rhythmic waves of contraction and they can be quite strong as in the peristaltic contractions that move food along the GI tract Contracts without external stimulation, dies react by stretching by contracting more strongly; has a nerve supply that is not necessary to initiate contractions buts serves to modify them; sympathetic stimulation decreases visceral smooth muscle activity, and parasympathetic stimulation decreases visceral smooth muscle activity MULTI-UNIT SMOOTH MUSCLE Large unit, multi-unit smooth unit is made up of individual smooth muscle cells or small groups of cells; found where small, delicate contractions are needed, contractions are not automatic and require specific impulses from autonomic nerves to contract They are specific and carefully controlled, allows fine control of actions and also allows delicate control of blood flow throughout the body and airflow through the lungs by adjusting the size of blood vessels and air passageways according to the body’s needs CHAPTER #12: BLOOD, LYMPH, AND LYMPH NODES BLOOD COMPOSITION o Blood- fluid connective tissue that flows throughout the entire body o Whole blood- contained in the cardiovascular system; peripheral blood- whole blood circulating in the blood vessels carrying oxygen, nutrients, and waste materials o Microscopically hole blood is a clear liquid (plasma) which has man cellular components suspended in it : erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets); five types of white blood cells: neutrophils, eosinophils, basophils, lymphocytes, and monocytes o Whole blood samples are commonly obtained from an animal’s vein using a needle and a vacuum tube in a process called venipuncture, tubes have differently colored stoppers or tops depending on which anticoagulant if they contain any, anticoagulants help blood from clotting after removed from the body o If the sample is allowed to clot in the tube that does not contain any anticoagulants then the remaining fluid is serum o CBC (complete blood count) and blood smear- use samples that are not allowed to clot; collected in purple top tubes which contain EDTA; EDTA prevents clotting by binding to calcium ions and preventing the clotting cascade o Green top vacuum tubes- contain heparin and used to analyze blood from small species like mice o If blood sample with anticoagulant is centrifuged then it separates into three layers based on the densities: less dense to most dense are plasma on top containing clotting proteins, buffy coat layer in the middle composed of leukocytes and thrombocytes and the red blood cell layer at the bottom o Plasma color varied from colorless to straw to yellow-orange depending on the species, diet, and any pathologic condition present: normal plasma is transparent, buffy coat is white or tan, bottom layer is red o Serum samples are collected in a red topped tube which do not have any anticoagulants and therefore allowed to clot; if centrifuged it will separated into two components: fluid that sits on top is serum, clot composed of all blood cells entwined in the fibrin clot is forced to the bottom of the tube o FUNCTION TRANSPORTATION Red blood cells contain hemoglobin which carries oxygen to every cell in the body, nutrients and other elements are dissolved in blood plasma and are transported to tissues by arteries and capillaries, waste products carried in blood by veins to lungs and kidneys where waste is eliminated in body, hormones from endocrine glands to target organs, white blood cells to areas where they are defending infections, platelets to the sites of damage in blood vessel walls to form a plug will control bleeding known as hemostasis and are involved in blood-clotting cascade REGULATION Regulation of body temperature; regulators are in the brain and are partially infected by temperature of the blood passes over them; tissue fluid content: plasma leaves the blood stream and enters the body tissues in an effort to compensate for fluid loss (hemoconcentrated) , less plasma in bloodstream and become more concentrated, too much body fluid then excess fluid enters the blood stream and dilutes the number of cells (hemodilution); aids in regulation of blood pH, normal PH ranges from 7.35-7.45 with ideal at 7.4, must be in this range for animal to remain healthy and remain slightly alkaline in order to buffer the acidic waste products of cellular metabolism, pH of arterial blood is slightly more alkaline than that of venous blood DEFENSE Carries white blood cells to tissues exposed to foreign invaders, help contribute to an animal’s immune system to help keep the animal healthy; carries platelets to sites of vessel damage to aid in hemostasis so animal does not bleed excessively HEMATOPOIESIS o Production of all blood cells that occurs continuously through an animal’s life; in fetus happens in the liver, in a newborn animal happens primarily in red bone marrow located in most of the bones of the body, many bones involved due to the high demand for blood cells during growth and development- rate slow as animal grows and some of the red bone marrow turns into yellow bone marrow when dominated by fat cells- can become reactivated by increased demand from the body o In adult, various sites of red bone marrow which varies by species, sites in skull, ribs, sternum, vertebral column, pelvis and proximal ends of femurs, daily produces billions of each cell type o Cells must be constantly replaced, liver and spleen are capable of hematopoiesis when in great need but not in a great capacity, o Bone marrow analysis are helpful when animals have a lower than normal white blood cell count, anemia, or when abnormal cells are seen on a blood smear o All blood cell types are derived from a single primitive stem cell type called a pluripotential or multipotential stem cell- these cells have potential to replicate and differentiate into many different discrete types of unipotential stem cell- they become specific mature cells through their individual maturation process: erythropoiesis, leukopoiesis or thrombopoiesis o Rate of hematopoiesis is regulated by stimulus called proteins, colony stimulating factors, or interleukins o ERYTHOPOIESIS Process by which red blood cells are created, unipotential stem cells are stimulated to differentiate into proerythroblasts which further divide multiple times through several stages where each stage produces a more mature cell type: a certain stage cells will lose their nuclei and stop multiplying and then start producing hemoglobin: have to mature through three more stages to become mature red blood cells Entire process occurs in 1 week for a dog, 4 to 5 days in a cow and 36 hours in a bird; controlled by hormones ( mainly erythropoietin) and availability of materials needed to make red blood cells: iron, folic acid, vitamin B12, and protein Erythropoietin- produced primarily by the peritubular interstitial cells of the kidney and regulated by the blood oxygen levels in the kidney o THROMBOPOIESIS Production of platelets which begins when a specific stimulant acts on the unipotential stem cell in the red bone marrow causing it to differentiate it into a megakaryocyte: large multinucleated cell which never leave the bone marrow Pieces of cytoplasm from the megakaryocyte are released into the peripheral blood as platelets, can take up to 7 days to reach completion o LEUKOPOIESIS Formation of white blood cells, each specific white type has its own stimulus for production, starts out with the same pluripotential stem cell produced proerythroblasts and megakaryocytes Granulopoiesis- pluripotential stem cell differentiates into one of three types of granulocyte: neutrophils, eosinophils, or basophils; early on they are not distinguishable because they appear as large cells with lots of cytoplasm, large round nuclei, and a first set on nonspecific granules Lymphocytes and monocytes develop from a pluripotential stem cell that has been stimulated from a specific stimulus; do not contain specific cytoplasmic granules and are known as agranulocytes Lymphopoeisis is the process that produces lymphocytes, some of which are developing outside of bone marrow Monopoiesis is the formation and maturation of monocytes CELLULAR COMPONENTS OF BLOOD: RED BLOOD CELLS o STRUCTURE Highly specialized, lack a nucleus, mitochondria, and ribosomes, but contain water, emoglobin, and other structural elements; under microscope, mature blood cells seem like non-nucleated biconcave discs with central zone whch is thinner and lighter in color Use glucose from plasma for energy; hemoglobin makes them stain red o FUNCTION Three main functions: Transporting oxygen to tissues: use hemoglobin, a protein that is formed during RBC development, made up of four heme units associated with one globin chain; heme unit is the pigmented portion of hemoglobin and contains an iron atom to which one oxygen molecule can attach; one hemoglobin can carry 4 oxygen: oxyhemoglobin- with oxygen; deoxyhemoglobin- without oxygen; blood pH, temperature, and blood levels of oxygen and carbon dioxide influence hemoglobin’s ability to carry oxygen Transporting carbon dioxide to the lungs; tissue cells take up oxygen from RBCs while RBCs collect carbon dioxide waste products from the tissue cells along with other waste where it breaks down to ions and transported to the lungs; some CO2 taken up is not bound to heme molecules but still taken up by RBC Maintaining cell shape and deformability: important to maintain biconcave shape as it provides more membrane surface area for diffusion of oxygen and carbon dioxide; allows for shorter diffusion distance in and out of the cell; deformability- refers to flexibility of the cell membrane, allowing it to change shape and travel through various blood vessels in the body o LIFE SPAN AND DESTRUCTION Normal life span in RBC varies per species: dog- 120 days, cats- 68 ddays, horse & sheep- 150 days, cows- 160 days, mice- 20 to 30 days; as they wear out, replace by young RBCs from red bone marrow in the never-ending erythropoiesis Aging of RBCs= senescence; as it becomes senescent, enzyme activity decreases, loses deformability by becoming rounder enclosing a smaller volume, 1% of aging, dead or abnormal RBCs are removed from circulation and destroyed each day and can occur intravascularly or extravascularly, free radicals contribute to the raid aging and destruction of red blood cells o EXTRAVASCULAR HEMOLYSIS 90% of destruction occurs this way- destruction of red blood cells outside of the cardiovascular system; removed by macrophages primarily in the spleen; membranes of phagocytized cells are ruptured and hemoglobin is degraded into amino acids, heme, and iron Amino acids returned to liver to build new proteins, iron transported to the bone marrow where it is recycled during erythropoiesis to make new red blood cells, heme broken down into free or unconjugated bilirubin: attaches to the plasma protein albumin and transported to the liver: made into glucuronic acid, conjugated bilirubin ecreted into the intestines from the liver as bile pigment where it is eventually converted into urobilinogen by intestinal bacteria, some urobilinogen is reaborsed and eliminated in the urine as urobilin, some is converted in stercobilinogen and is excreted in feces as stercobilin o INTRAVASCULAR HEMOLYSIS 10% of destruction done in the blood vessels, exposed to many oxidative stresses which can result in RBC fragmentation and/or destruction; rupturing in vessel and the hemoglobin is directly released into the bloodstream; hemoglobin is picked up by haptoglobin which is a transport protein in plasma, the new hemoglobin-haptoglobin complex travles to the macrophages in the live for further breakdown When severe hemolysis occurs, unconjugated hemoglobin will appear in the plasma leaving it a pink, red or brown color which is called hemoglobinemia: has no way to get to the liver so it is carried to the kidney where it is eliminated in the urine making it red in color which is called hemoglobinuria o COMPLETE BLOOD COUNT Used to evaluate plasma proteins, red blood cells, white blood cells, and platelets, one of most useful clinical evaluations performed on a patient PACKED CELL VOLUME OR HEMATOCRIT Volume of packed RBCs measured and expressed as a percentage of a total volume of blood, two ways to determine PCV are blood analyzers and gross examination of a centrifuged microhematocrit tube Microhematocrit tubes are plugged with clay and spun in the microhematocrit centrifuge, causing the separation of the blood sample into three layers: plasma, buffy coat, and RBCs; PCV measured by putting tube on special card so top of clay lines up with the 0% line, tube rolled along the card until the top of the plasma intersects the 100% line, line which intersects top of the RBC layer is the PCV value and measured in a percentage Anemia- can result if animal’s PCV being lower than normal reference range; leads to decreased oxygen carrying capacity of blood Polycythemia- animal’s PCV being higher than normal or increase in red blood cells; three types: o Relative: seen when there is a loss of fluid from blood, such when animal is dehydrated o Compensatory: result of hypoxia, bone marrow stimulated to make more RBCs because the tissues aren’t getting enough oxygen, can be developed by animals living at high altitudes o Polycythemia rubra vera- rare bone more disorder characterized by increased production of RBCs for an unknown reason HEMOGLOBIN o Measures concentration of hemoglobin contained in the red blood cells in a specific volume of blood RED BLOOD CELL COUNT o Measures the number of RBCs in a specific volume of blood MEAN COPUSCULAR VOLUME o Measures the average volume or size of the individual red blood cells, helpful way to evaluate RBCs in the sample MEAN CORPUSCULAR HEMOGLOBIN CONCENTRATION o Another parameter that is clinically helpful to evaluate the RBCs in the presence of anemia, measures ratio of the weight of hemoglobin to the volume of the RBCS RED CELL DISTRIBUTION WIDTH o Numerical expression of variation in the red blood cell size, variation in size is called anisocytosis, can be seen in severe anemia where the bone marrow is pumping RBCs out at such a high rate they don’t have time to mature fully, immature RBCs are larger than fully mature RBCs in circulation RETICULOCYTE COUNT o Count of number of immature forms of red blood cells per a specific total number of red blood cells, used to characterize type of anemia in the animal TOTAL LEUKOCYTE COUNT o Express the total number of white blood cells in a specific volume of blood, # of each type of white blood cell is also counted either by an automated blood analyzer or by evaluating a stained blood smear o Neutrophilia- higher than normal neutrophils, will also increase the total number of WBCs= leukocytosis, neutropenia= too little neutrophils, too little WBCs- leukopenia PLATELET COUNT o Measures the total number of platelets in a specific volume of blood sample, thrombocytosis= higher than normal, thrombocytopenia= lower than normal TOTAL PLASMA PROTEIN o Measures the amount of protein in the plasma portion of a specific volume of blood, can be measured by automated blood analyzer or a hand- held refracter STAINED BLOOD SMEARS Made from a patient’s blood sample, stained, and evaluated to supplement a CBC, known as the differential count Combinations of blue and red dyes dissolved in methyl alcohol: commonly used is wright’s stain which contain blue and red-orange dyes, methylene blue will stain acidic structures such as RNA or DNA a blue/ purple: nuclei will stain blue/purple; hemoglobin and some cytoplasmic granules are stained orange or red by the eosin dye component PLATELETS o Known as thrombocytes, not complete cells but pieces of cytoplasm tht bud off from giant, multinucleated bone marrow cells called megakaryotes and sent into circulation o STRUCTURE On a blood smear- appear nonnucleated, round to oval in shape which contains small blue and purple granules; granules contain clotting factors and calcium, size of platelets vary by species, generally smaller than RBCs but sometimes macroplatelets can be seen; more metabolically and functionally active in larger form, released when the consumption of platelets is being exceeded o FUNCTION Most important for normal hemostasis- process by which blood is prevented from leaking out of damaged blood vessels, have specific roles in clotting process, along with endothelial cells in the blood vessel wall and coagulation factors: two specific function in hemostasis: formation of the platelet plug and stabilization of the plug Subendothelium of a blood vessel when exposed from a blood vessel attracts platelets to it which is known as platelet adhesion, endothelium produces tissue factors that activate the coagulation cascade to form thrombin Thrombin causes platelets to change shape and develop pseudopods that allow them to intertwine with each other, thrombin coverts fibrinogen to fibrin which attaches to the platelet surface and ultimately help cement the platelets in place o COAGULATION CASCADE Series of reactions that result in inactive enzymes being activated by the preceding enzyme in the cascade, one a factor is activated and it will cause the activation of the next factor which will eventually lead to the generation of large quantities of fibrin on the aggregated platelets’ surface, clot also acts as a scaffolding for repair of the damaged vessel o LIFE SPAN AND DESTRUCTION Circulate for approximately 5 to 7 days, liver produces thrombopoeitin which regulates the number of platelets circulating the body, removed by macrophages during circulation because of old age or damage WHITE BLOOD CELLS o Mature WBCs are generally larger than mature RBCs, five types of WBCs circulating in the blood and classified into agranulocytes and granulocytes based on granules when they are stained, granulocytes- neutrophils, eosinophils, and basophils; agranulocytes- lymphocytes and monocytes NAME CYTOP NUCLEAR SHAPE FUNCTION SITE OF LASMIC ACTION GRANU LES NEUTROP DON’T POLYMORPHONUCL PHAGOCYTO BODY HIL STAIN EAR SIS TISSUES WELL EOSINOPHI STAIN POLYMORPHONUCL ALLERGIC BODY L RED EAR REACTIONS, TISSUES ANAPHYLAXI S, PHAGOCYTO SIS BASOPHIL STAIN POLYMORPHONUCL INITIATION BODY BLUE EAR OF IMMUNE, TISSUES ALLERGIC REACTIONS MONOCYT NONE PLEOMORPHIC PHAGOCYTO BODY E SIS, TISSUES PROCESS OR ANTIGENS BLOOD (MACROPHA GE) B CELL- NONE MONONUCLEAR ANTIBODY LYMPHOI LYMPHOCY PRODUCTION D TISSUE TE , HUMORAL IMMUNITY T CELL- NONE MONONUCLEAR CYTOKINE LYMPHOI LYMPHOCY PRODUCTION D TE , CELL- TISSUES MEDIATED AND IMMUNITY OTHER BODY TISSUES o FUNCTION Provide defense for the boy against foreign invaders, each cell has its own unique role in defense, if all WBCs working properly animal has good chance of remaining healthy Use peripheral blood to travel from bone marrow production site and to the tissues, constant flow in order to attack invaders in animal body, two types of defense function: phagocytosis and immunity o GRANULOCYTES Neutrophils, eosinophils, and basophils; all contain granules in their cytoplasm when view on a stained blood smear, eosinophils appear red, basophils appear blue, and neutrophils near with no color NEUTROPHILS Account for 40-75% of circulating leukocytes and are the most abundant white blood cell type in the blood of dogs, cats, and horses Larger than RBCs and smaller than monocytes, their nuclei become lobulated or segmented and take on mnay different shapes, can have from two to five nuclear segments Spends average of 10 hours in circulation before it enters a tissue, shorter when there is increased demand, all neutrophils need to be replaced two and a half times a day In peripheral blood, two pools of neutrophils- circulating pool represents the blood as it flows through the blood vessels, can be seen in blood samples; marginal pool- represents neutrophils that line the walls of small blood vessels, mainly in the spleen, lungs, and abdominal organs, non circulating Stay in tissues until they die of old age or are destroyed by the microrganisms they are trying to destroy, dead or abnormal ones are picked up my tissue macrophages Band neutrophils= mmature neutrophils, if seen in peripheral blood it is seen in peripheral blood the condition is called a left shift FUNCTION o Involved in early stages of the inflammatory response, second defense by traveling quickly to the inflamed tissue o Leave blood vessels by squeezing between the cells of the endothelium called diapedesis- attracted to site of infection by chemotaxis: process by which neutrophils and other cells are attracted by the inflammatory chemicals produced by the interaction between microorganisms and the tissues they are invading o Neutrophils can phagocytize, or engulf microorganisms such as bacteria, granules contain digestive enzymes that are capable of destroying bacteria and viruses that have been engulfed, bacteria enclosed in pouch called the phagosome in the neutrophil, release of lysosomal enzymes by granules help kill bacteria o Hydrogen peroxide is product of oxygen metabolism that is most important for the killing activity of neutrophils, capable of killing the bacteria all by itself but it is enhanced by the enzyme myeloperoxidase, lysozyme from granules also enhances the bactericidal action of hydrogen peroxide and is capable of destroying the cell walls of microorganisms EOSINOPHILS Named for red granules in the cytoplasm of mature cells, 1-6% of all circulating WBCs, bi-lobed nuclei with red granules in the nucleus, slightly larger than neutrophils, stay in circulation for 3 to 8 hours before migrating to tissues where they live the rest of their life, increased number in peripheral blood= eosinophilia, decreased number in peripheral blood- eosinopenia FUNCTION o Similar to neutrophils and include phagocytosis and bactericidal properties but to a lesser extent, phagocytic cells, especially of antigen-antibody complexes, large numbers of eosinophils normally found in certain tissues in the body such as GI tract, skin & lungs o Three key functions: inflammatory response: attracted to and inhibit local allergic and anaphylactic reactions, granules contain anti- inflammatory substances that are released at the site of an allergic reaction; immunity: can ingest substances associated with the humoral immune response; phagocytosis: minimal phagocytic and bactericidal functions, contents of granules are especially toxic to large pathogenic organisms BASOPHILS Least common leukocyte less than 1% of circulating white blood cells, difficult to quantify to little (basopenia) or too many (basophilia) basophils, recognized by their large intensely staining basophilic or blue cytoplasmic granules, granules are water soluble and frequently washed out during the staining process Multi-lobed nuclei are similar in size to neutrophils, shared some characteristics with tissue mast cells in that both contain immunoglobulin E but some controversy exists over the relationship between these two cells FUNCTION o Least phagocytic of the granulocytes, granules contain heparin and histamine- histamine= helps initiate inflammation and acute allergic reactions, attracted to the site of an allergic reaction by eosinophilic chemotactic factor released from granules o AGRANULOCYTES Mature white blood cells that do not contain specific staining granules in their cytoplasm, include lymphocytes and monocytes LYMPHOCYTES Have round or oval nucleus and minimal amount of clear, almost colorless cytoplasm, live in lymphoid tissues and constantly circulate between these tissues and blood, lymphocytosis= increase, lymphopenia= decrease FUNCTION o Four main types: T cells, B cells and transform into plasma cells, natural killer cells o T-cells- processed in the thymus before going to peripheral lymphoid tissue, help in cell mediated immunity and for activating B cells o B-cells- inactive travel through lymph nodes, spleen and other lymphoid structures, rarely circulate in peripheral blood, responsible for humoral immunity, each B cell is preprogrammed to only produce one specific type of antibody against one antigen Each B cell ha thousands of receptors shaped to fit only one antigen shape, unique shape for every antigen, area is the epitope and sequence of amino acids determines the shape, B cell has complementary receptor that fits the shape of the epitope, antigen- antibody complex is formed when the B cell and antigen are joined o Plasma cells- derived from B cells in response to an antigenic stimulus, b cells which are activated multiply by mitosis in a process called blastic transformation to become plasma cells; plasma cells- produce, store, and release antibodies known as immunoglobulins, can be found in any cell in the bodybut most numerous in tissues involved in antibody formation. Rarely found in peripheral blood o Natural killer (NK) cells- found in blood and lymph, able to identify and kill virus-infected cells, stressed cells, and tumor cells, differ from phagocytes in that they do not ingest the target cell but instead they bind to the cell and induce cellular changes that lead to apoptosis or cell lysis o Apoptosis instead of cell lysis is triggered in virus infected cells to ensure the death of the virus which lysis does not o Have two types of receptor to help determine which cells to kill: killer-activating receptor (KAR) and the killer inhibitory receptor (KIR); KIR binds with specific molecules on the cell surface and this binding demonstrates that cell is healthy and inhibits NK cell from killing it and if it does not bind it will kill the cell; when there is decreased expression of specific molecules on the cell’s surface, KAR is trigged to cause apoptosis, killed because could be unhealthy o NK cells are stimulated by cytokines, including interleukins and interferons; tumor, damaged, and infected cells release cytokines as stress signals which stimulates NK cell action and ultimate destruction of harmful cells o T and B cell can become memory cells, clones of an original lymphocyte, do not participate in the initial immune response to a specific antigen but survive in lymphoid tissue waiting for a second exposure to the same antigen MONOCYTES o Make up 5-6% of circulating WBCs in all common
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