Title | A&p exam 3 - Study guide for exam 3, Dr. Cummings, Fall 2016 |
---|---|
Course | Human Anatomy & Physiology |
Institution | Clemson University |
Pages | 15 |
File Size | 482.3 KB |
File Type | |
Total Downloads | 92 |
Total Views | 149 |
Study guide for exam 3, Dr. Cummings, Fall 2016...
Anatomy and Physiology Exam 3 Study Guide Dr. Cummings
Muscle Tissue Identify the criteria used to classify muscle, then differentiate the three muscle types using these criteria. Criteria = striations, nervous control, number of nuclei. Skeletal striated, voluntary, multinucleated Cardiac striated, involuntary, one nucleus (intercalated discs, striations branch more) Smooth non-striated, involuntary, one nucleus (“spindle cells” because they taper at both ends) Describe the properties common to all muscle types. Excitability = responds to a stimulus Contractility = ability to shorten/thicken; no muscle will contract unless it is stimulated to contract impulse carried by nervous system, muscle reacts by contracting Extensibility = can stretch, work in antagonistic pairs in skeletal muscle Elasticity = can return back to resting state after shortening/thickening Explain the functions of muscle. Motion – any muscle contraction results in motion Contraction of cardiac muscle moves blood Contraction of smooth muscle propels food, releases urine Contraction of skeletal muscle = locomotion Maintenance of posture – skeletal muscle contraction opposes gravity Stabilizing joints – muscles surround join are partially contracted to give strength Heat production – any muscle contraction produces heat Examine the gross anatomical features of skeletal muscle. Muscle = 100s-1000s of individual muscle cells Skeletal muscle fibers Blood vessels – deliver oxygen and glycogen Nerve fibers – carry impulse for stimulation Connective tissue Attachment – indirect or direct; tendons and aponeurosis Epimysium = connective tissue around the entire muscle; dense irregular connective tissue Fascicle = bundle of muscle cells, covered by the perimysium Perimysium = connective tissue covering fascicle Muscle fiber = muscle cell = myofiber Endomysium = connective tissue surrounding the individual musc cell; reticular connective tissue
Describe the types of muscle attachments. Direct attachment = muscle fuses to periosteum Indirect attachment = tendon attaches muscle to bone Tendon – rope-like extension of connective tissue Aponeurosis – sheet of connective tissue (palmar aponeurosis) Origin = attachment of the muscle to the immovable bone Insertion = attachment to the movable bone Can have more than one origin/insertion Explore the microscopic anatomy of skeletal muscle and the specific arrangement of each element in relation to the others. Myofibers – cells run the length of the muscle Sarcolemma – plasma membrane of a muscle cell; given a special name because of change in the cell during embryonic development Sarcoplasm – cytoplasm of a muscle cell; store their own glycogen for contraction o Myoglobin = pigment that stores oxygen in muscle Nuclei – multiple per cell Myofibrils – contractile components of muscle; myofibers contain myofibrils Sarcoplasmic reticulum – modified ER, surrounds the myofibrils T tubule – 1/3 of a triad, run longitudinally; interrupted by terminal cisternae (perpendicular channels, 2/3 of triad)
Describe the structural arrangement of a sarcomere.
Sarcomere = z line to z line Thin myofilaments connected to the Z line Myosin pointing away from M line = higher energy configuration Z line = ends of sarcomeres A band = where thick and thin are together I band = doesn’t have thick myofilaments H zone = only thick myofilament Identify the proteins associated with the myofilaments. Thick myofilaments = myosin Actin binding site (connects thick and thin myofilaments) ATP binding site Two heads per myosin Thin myofilaments = actin Tropomyosin wraps around to give strength Troponin – always connected to tropomyosin o Troponin I – attaches to actin o Troponin T – binds to tropomyosin o Troponin C – binds to calcium disables troponin I so it can no longer be attached to actin Explain the sliding filament theory of muscle fiber contraction. Actin (thin) filaments slide past the myosin (thick) filaments, using the actomyosin crossbridge Describe the structural arrangement of the neuromuscular junction, and explain the mechanism of generation of an action potential across the sarcolemma. One neuromuscular junction per fiber No direct connection: synaptic cleft = small space between nerve and muscle cell Synaptic vesicles contain neurotransmitters ACH = acetylcholine Signal comes down the neuron, causes the vesicles to release ACH through exocytosis (caused by calcium fusing with vesicles), which bind to receptors on sarcolemma Motor end plate o Ach receptors found at motor end plate only o Acetylchonesterase breaks down Ach
Ach triggers generation of action potential across sarcolemma and down T tubules o Opens sodium channels so sodium moves into, cell becomes depolarized o Action potential passes triads +30 mV o Terminal cisternae release calcium into sarcoplasm o Some calcium binds to troponin removes tropomyosin from active sites on actin o Myosin heads attach to actin and pull thin myofilaments toward center of sarcomere o Power stroke Thick and thin myofilaments found through cross bridge Myosin head changes from high energy to low energy configuration Pulls thin myofilament toward H zone ATP binds with myosin head Myosin and actin separate ATPase splits ATP and released energy returns myosin head to high energy position Cycle repeats in presence of calcium and ATP
Describe a motor unit, and explain how these can affect the strength of muscle contraction. Motor unit = motor neuron and all the fibers its stimulates Not all motor units in a muscle fire at the same time, which allows it to stay active longer Each muscle fiber has only one neural connection Strength of contraction is determined by the number of motor units involved
Muscle Contraction *no muscle will contract unless it is stimulated to contract* Describe the different types of muscle contraction, and explain how wave summation operates in these various types. Twitch: single stimulus in response to a single stimulus o More motor units = more tension o Latent period = period of time between stimulation and the beginning of activity Time of Ach to open sodium gates and going through tubules and releasing calcium o Relaxation phase – sodium goes back out o A second stimulus applied before complete contraction and relaxation won’t cause anything to happen Refractory period = time in which a second stimulus will not evoke a response Tetanus: second contraction due to second stimulus before complete relaxation o Must come during the relaxation phase, after the refractory period
o Incomplete tetanus = partial relaxation Wave summation – second stimulus applied before complete relaxation; strength increases with each additional stimulus, to a maximum o Complete tetanus = no relaxation Treppe: muscle completely relaxes but contractions get stronger o More efficient process Isotonic: effort exceeds the load, muscle shortens and changes shape Isometric: load exceeds effort no movement
Describe the mechanisms through which muscles are supplied with ATP. Direct phosphorylation o Creatin phosphate couples with ADP to produce ATP o Occurs within cytoplasm of the cell o Power muscle up to 15 seconds o CP reserves replenished during inactivity Anaerobic respiration – if oxygen isn’t present o Glycolysis breaks down glucose (cytoplasm) o Pyruvic acid converted to lactic acid o Lactic acid diffuses into bloodstream, travels to the liver, which turns to pyruvic acid, and turns into glucose o Power muscle up to 1 minute o Lactic acid shuts off ATP Aerobic respiration o Glycolysis breaks down glucose o Produces lots of ATP o Pyruvic acid enters mitochondria for complete breakdown Explain the factors that can affect the force of a muscle contraction. Number of fibers stimulated o More fibers/motor units = stronger contraction Relative size of fibers o More storage in the cell = larger = greater strength Frequency of stimulation o More frequent = stronger Degree of stretch o More overlap = less force o No overlap = no force of contraction Differentiate the types of skeletal muscle fibers. Based on speed of contraction and how ATP is produced: Slow oxidative fibers o Slow contraction o Aerobic (oxygen) o Very fatigue-resistant
o Ex: long distance runner Fast oxidative fibers o Fast contraction (split ATP quickly) o Aerobic (oxygen) o Relatively fatigue-resistant, but might run out o Ex: sprinter Fast glycolytic fibers o Fast contraction (split ATP quickly) o Anaerobic o Prone to fatigue, but get big burst of contraction o Ex: weightlifter
Indicate the microscopic anatomy of smooth muscle cells, and compare this to skeletal muscle cells. Smooth fibers smaller than skeletal fibers (shorter cells) Lack connective tissue sheaths only endomysium (no peri or epi) Organized into sheets o Longitudinal layer o Circular layer Unstructured neuromuscular junction o Autonomic nerve activates smooth muscle from the involuntary part of the brain o Repeated bulbous swellings (variscosities) that contain vesicles that hold neurotransmitters o Variscosities release neurotransmitters into diffuse junctions entire surface of the muscle has neurotransmitter receptors Less developed sarcoplasmic reticulum o No triad arrangement o Touches sarcolemma, but no organized pattern to the myofilaments o No sarcomeres o No T tubules Caveoli – infoldings of sarcolemma that holds concentrated calcium in pouches so that it is available when the cell needs it Myofilament arrangement o 10-15 thin myofilaments for each long, thick myofilament o Myosin heads found along entire length of thick myofilament o Tropomyosin associated with thin myofilament, but no troponin Nothing to cover myosin binding sites, but cross bridges are in low energy configuration and can’t bind to them o Myofilaments arranged diagonally within fibers o Intermediate filaments – non-contractile element Attach to dense bodies and stretch from one to another Dense bodies attached to sarcolemma
Describe the types of smooth muscle and identify their locations within the body. Visceral – contracts rhythmically as a unit Peristalsis: wave-like contraction of smooth muscle Cells are coupled with gap junctions, which makes it work as a unit Found in the walls of hollow internal organs Multiunit No gap junctions Pupil and arrector pilli Walls of large arteries Describe the mechanism and regulation of smooth muscle contraction. Mechanism: Neurotransmitter stimulates production of action potential changes membrane permeability Calcium released by caveoli Calcium binds to calmodulin (smooth muscle doesn’t have troponin) Activated calmodulin activates myosin light chain kinase Activates kinase charges myosin cross bridges Actin and myosin interact to shorten fibers In smooth muscle, actin is ready to go, but myosin isn’t (opposite of skeletal) Regulation: Autonomic nerves release different neurotransmitters o Excitatory or inhibitory Chemical factors o Hormones independent of neurotransmitters (uterine contractions) o Histamine (allergic response) o Excessive CO2 o Changes in pH Identify the embryonic development of muscle tissue, and outline the changes in muscle tissue that occur due to age. Muscle tissue develops from the mesoderm Skeletal myoblasts (mesodermal cells) fuse long, multinucleated o Cardiac and smooth do not fuse; develop gap junctions instead shorter cells Agrin clusters and maintains Ach receptors, only at the motor end plate All myoblasts have neurotransmitter receptors over entire sarcolemma Muscles change because of agrin (growth factors), which creates neuromuscular junction and neuro end plate, acetylcholine receptors remain at that site
Muscle Mechanics Describe the origin, insertion and belly of a muscle, and explain how each function to invoke movement. Origin – attachment to stationary bone
Insertion - attachment to movable bone Belly – fleshy, meaty part of the muscle (gaster)
Define a lever, and describe the two forces acting on it. Lever – rigid structure that moves about a fixed point called fulcrum o Joints = fulcrum, bones = rigid structures Resistance (load) – force that has to be overcome for movement to occur Effort – force exerted to overcome the resistance If the load is closer to the fulcrum than the effort is, there is mechanical advantage, making it easier for things to be moved Differentiate the three classes of levers. 1) First class Fulcrum between load and effort Head on shoulders o Load = weight of head o Effort = contraction of muscles on back of neck 2) Second class Resistance is between fulcrum and effort Can have mechanical advantage – require less fibers Standing on tip toes 3) Third class Effort is between fulcrum and load Mechanical disadvantage Require more fibers to overcome mechanical disadvantage Describe the functional groups of muscles. Agonist (prime mover) – muscle that is primarily responsible for bringing movement about Antagonists – opposite movement of agonist Synergists – accessory muscles that help to steady the movement; assist agonist Fixators – stabilizes the origin of the agonist Identify the criteria used for naming muscle. Location Shape Size o Oblique = diagonal o Rectus = parallel Direction of muscle fibers Number of origins Location of attachment (origin comes first in naming) Action (flexers, abductors)
Indicate the most common arrangements of fasciculi in skeletal muscle. Parallel o Sartorius o Parallel to longitudinal axis of the muscle Convergent o Broad at origin but narrows at the insertion o All of the fasciculi are arranged toward the insertion Pennate – tendon runs entire length of muscle, fibers are short and orient toward tendon o Unipennate: all fasciculi on same side o Bipennate: on both sides o Multipennate: multiple tendons Circular – around an oris Long fibers = increased range of motion Short fibers = relatively small range of motion Power of muscle is determined by number of fibers that the muscle possesses
Neurophysiology Identify the functions of the nervous system. Sense change o First response to stress is through the nervous system (immediate) o Chemical response is secondary Interpret change – central nervous system Respond – based on the interpretation o Detect change interpret what it means send response List the structural and functional divisions of the nervous system, and describe their relationship to one another. Central Nervous System – receives all sensory information and initiates responses Peripheral Nervous System – connects CNS to everything; extensions off brain = cranial nerves; extensions off spinal cord = spinal nerves Afferent division – carries sensory information to CNS Efferent division – carries motor information away from CNS o Somatic nervous system – attaches to a skeletal muscle to innervate to cause contraction; under conscious control o Autonomic nervous system – motor neurons that innervate cardiac or smooth muscle; involuntary control Sympathetic division – fight or flight, survival Parasympathetic division – housekeeping tasks
Discuss the anatomy of a neuron and the function of each structure. Neurons = structural and functional units of the nervous system; conduct nervous impulses; 50% of nervous tissue Cell body – nucleus and all organelles o Perikaryon = soma = portion of the cell that contains all of the cellular components Chromatic substance (Nissl bodies): specialized rough endoplasmic reticulum; proteins used for neural growth lots in embryo, and used for peripheral regeneration (fixing damage) Neurofibrils: microtubules of cytoskeleton, function in support and to distribute nutrients Lipofuscin: yellow-brown pigment (cell inclusion), not sure what it does, mostly accumulated in elderly Dendrites – numerous short extension of cytoplasm Axon – single, long extension away from the cell body o Axon hillock: point at which the axon leaves the cell body; attachment part o Telodendria: end of the axons o Synaptic knobs: vesicles on ends telodendria, contain neurotransmitters o Axon collaterals = branches o Myelin sheath: made of lipid, protects axon, speeds up conduction of impulse along axon Innervation is transmitted dendrites cell body axon (ONLY DIRECTION) Explain the physiological characteristics of mature neurons. Longevity – function for lifetime, develop in embryo Lose ability to divide – cannot replicate, always in G0 High metabolic rate – requires lots of energy and glucose Describe the types of glial cells, their functions and their locations in the nervous system. Neuroglia = all cells that nourish, protect, and support neurons CNS glial cells: Astrocytes o Most abundant in body o Attach neuron to blood vessel o Anchoring component to hold things in place o Coordinate the exchange between the neuron and the bloodstream (BBB) Regulates internal chemical environment of the neuron (prevent bacteria from getting into the brain from the bloodstream) Oligodendrocytes o Produce the myelin sheath around the axons of the CNS Microglia o Immune role o Get rid of pathogens (macrophages) Ependyma o Form the epithelial lining of the brain and spinal cord
PNS glial cells: Satellite cells o Exist between adjacent cell bodies o Many present o Function has not been identified Schwann cells o Create myelin sheath around axons in PNS o Produce lipids that are exported and accumulate around the axon
Describe the anatomy and function of the myelin sheath, and differentiate between myelinated and unmyelinated neurons. In the PNS: made by Schwann cells, nodes of Ranvier = gaps in myelin sheath In the CNS: made by oligodendrocytes, wider nodes of Ranvier Made of lipid Protects axon Speeds up conduction of impulse along axon o Faster because the ions skip down over the nodes of Ranvier Define the structural and functional categories of neurons. Structural classification is based on the number of processes coming off of the cell Multipolar o Several short dendrites o One long axon o Most prevalent Bipolar o One dendrite and one axon, which are on opposite ends of the cell body o Only found in special sense organs (vision, hearing, balance); receptors Unipolar o Only have on process, which acts as both the dendrite and the axon o Mostly sensory Functional classification is based on the direction of impulse transfer (toward or away from CNS) Sensory neuron o PNS CNS o Most are unipolar Motor neuron o CNS PNS o To muscle or gland Interneuron o Entirely in the CNS o Most are multipolar Reflexes go to the spinal cord for decoding Explain the resting membrane potential and how it is generated.
Resting membrane potential is the polarization of the membrane when at rest. It is due to the movement of sodium and potassium ions -70mv Inside of the cell is negative in relation to the surrounding extracellular fluid Identify how changes in membrane potentials act as signals, and relate each type of signal to the generation of an action potential. Stimulus is applied to polarized neuron localized change in membrane permeability Depolarization = making the cell less negative Describe the threshold stimulus. Discuss how it related to graded potentials and the all-ornone behavior of axons. Threshold stimulus = minimum potential at which an action potential will be caused All or nothing: no action potential if stimulus does not reach threshold; it either is reached or not reached, there is not intermediate Graded potentials cause gated ion channels to open o Inflow of positive ions changes membrane potential in localized region, causes change in permeability in local regions o Produced by sensory neuron (temp, light) o Short term reversal in permeability that results in polarization or depolarization Action potentials are initiated by graded potentials that cause depolarization of the resting neuron
Neural Integrat...