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A & P Unit 3 Exam
Anatomy & Physiology 1
| Term | Definition |
|---|---|
| Endomysium | extracellular matrix that surround muscle fiber |
| Fascicle | a bundle of many muscle fibers enclosed by the perimysium |
| Epimysium | wraps many fascicles that are in the whole muscle |
| What contributes to the appearance and function of a skeletal muscle? | The pattern of fascicle arrangement |
| Muscle orientations? | parallel, convergent, pennate, circular, and spiral |
| How are muscles usually named? | By their shape, appearance, size, position, or other structural considerations, like number of heads |
| What is a muscle's action? | a skeletal muscle that moves the bone it is attached to |
| Functions of skeletal muscles | facial expression, breathing, generating heat to regulate body temperature |
| Origin | a stationary point of attachment |
| Insertion | a more mobile point of attachment |
| Lever system | bones and muscles working together |
| Fulcrum | a joint formed by the connection of two or more bones |
| First-class lever | fulcrum is between the point of force and the load to be moved |
| Second-class lever | load to be moved is between the point of force and the fulcrum |
| Third-class lever | point of force is between the load to be moved and the fulcrum |
| Three types of muscle tissue? | skeletal, cardiac, and smooth |
| Muscle tension | this is generated when muscle cells contract by turning chemical energy into mechanical energy |
| Common muscle tissue properties | contractility, excitability, conductivity, distensibility, and elasticity |
| Sarcolemma | the plasma membrane of a muscle cell |
| Sarcoplasm | the cytoplasm of a muscle cell |
| What does the sarcoplasm contain? | myofibrils and the sarcoplasmic reticulum (SR) |
| T-tubules | inward extensions of the sarcolemma that surround myofibrils |
| Myofilaments | what myofibrils are composed of |
| Contractile, regulatory, and/or structural proteins | what myofilaments are composed of |
| Thick filaments | composed of myosin, a contractile protein |
| Thin filaments | composed of contractile actin proteins and the smaller regulatory proteins troponin and tropomyosin |
| Elastic filaments | composed of the structural protein titin |
| Striations | different arrangements of myofilaments in skeletal muscle tissue |
| I bands | light regions of striations where only thin filaments are found |
| Z-disc | found in the middle of each I band |
| A bands | dark regions of striations where the thick and thin filaments overlap |
| H zone | central region of A band |
| M line | where the H zone is bisected |
| Sarcomere | functional unit of contraction, one Z-disc to the next |
| Sliding-filament mechanism | thick and thin filaments slide past each other, muscle contraction |
| Electrical potential | separation of charges across the sarcolemma |
| Membrane potentials | electrical potentials across plasma membranes |
| Resting membrane potential | unstimulated muscle fiber that shows a decrease in voltage across the membrane |
| Two types of channels | leak and gated channels |
| Sodium/Potassium pump | maintains the gradient of sodium being higher in the extracellular fluid and potassium being higher in the cytosol |
| Electrochemical gradient | the sum of the concentration gradient and the electrical gradient |
| Action potential | a temporary, quick reversal in the membrane potential |
| Depolarization | Na+ enters the muscle fiber, causing the membrane potential to become more positive |
| Repolarization | K+ exits the muscle fiber, causing the membrane potential to return to its resting state |
| Motor neurons | this is what innervates skeletal muscle fibers |
| NMJ | neuromuscular junction |
| What does the NMJ contain? | the axon terminal, synaptic cleft, and the motor end plate |
| Excitation phase | the axon terminal releases ACh into the synaptic cleft |
| ACh stands for? | acetylcholine |
| End-plate potential | ACh receptors bind to the motor end plate |
| Excitation-contraction coupling | End-plate potential triggers an action potential in sarcolemma, this spreads down the T-tubules. It then triggers the SR to open Ca2+ channels and flood the cytosol. |
| SR stands for? | sarcoplasmic reticulum |
| Contraction phase | actin and myosin filaments interact with each other, causing the muscle to shorten and generate force |
| Crossbridge cycle | ATP hydrolysis "cocks" the myosin head and binds it to actin |
| Power stroke | myosin will pull actin toward the center of the sarcomere |
| Muscle relaxation | ACh in synaptic cleft is broken down and Ca2+ concentration returns to resting level within the cytosol |
| Creatine phosphate | stores ATP |
| Glycolytic catabolism | glucose in cytosol is split and ATP is produced |
| Oxidative catobolism | fatty acids and amino acids are oxidized to generate ATP |
| Twitch | a single contraction-relaxation cycle of a muscle fiber |
| Contraction-relaxation cycle consists of? | latent period, contraction period, and relaxation period |
| Two classifications of muscle fibers for twitches | fast-twitch or slow-twitch fibers |
| Unfused tetanus | muscle fiber is stimulated before the end of relaxation period |
| Fused tetanus | muscle fiber is stimulated 80-100 times before relaxation period begins |
| Type 1 muscle fibers | slow-twitch fibers that use primarily oxidative catabolism |
| Type 2 muscle fibers | fast-twitch fibers that use primarily glycolytic catabolism |
| Motor unit | a single motor neuron and the muscle fibers it innervates |
| Recruitment | when more motor units are activated for more forceful contractions |
| Muscle tone | small, involuntary contractions of alternating motor units |
| Three types of muscle contractions? | isotonic concentric contraction, isotonic eccentric contraction, and an isometric contraction |
| Atrophy | muscle fibers weaken and shrink |
| Functions of smooth muscle tissue | peristalsis, forming sphincters, and regulating the flow of material through hollow organs |
| How does a smooth muscle cell contract | by Ca2+ binding to calmodulin |
| Single-unit smooth muscle cells | contract together as a single unit |
| Multi-unit smooth muscle cells | contract independently of one another |
| Two structures nervous system is divided into | central nervous system (CNS) and the peripheral nervous system (PNS) |
| What makes up the CNS? | the brain and spinal cord |
| What makes up the PNS? | cranial and spinal nerves |
| PNS sensory division contains? | somatic sensory division and the visceral sensory division |
| Integration | the CNS receives the sensory input and processes it |
| PNS motor division contains? | somatic motor division and the autonomic nervous system (ANS) |
| What does nervous tissue consist of? | neurons and neuroglial cells |
| Neurons | excitable cells that send, propagate, and receive action potentials |
| What do neurons consist of? | cell body, one or more receptive dendrites, and a single axon |
| Oligodendrocytes | form the myelin sheath |
| Schwann cells | another name for the myelin sheath |
| What does the myelin sheath do? | it speeds up the conduction of an action potential through the axon |
| How many millivolts is the resting membrane potential? | About -70mV |
| What are leak channels? | These are proteins in the cell membrane that constantly allows ions to pass through |
| What are gated channels? | These are proteins in the cell membrane that allow ions to pass through by opening and closing in response to signals |
| What is the concentration of K+ and Na+ during resting membrane potential? | There is a higher concentration of Na+ in the extracellular fluid and there is a higher concentration of K+ in the cytosol |
| Local potential | small, local change in membrane potential of a neuron |
| Depolarize | makes the neuron less negative |
| Hyperpolarize | makes the neuron more negative |
| Action potential | rapid depolarization and repolarization of the membrane potential of a cell |
| Depolarization phase | Na+ floods the axon, causing membrane potential to rise toward a positive value |
| Repolarization phase | K+ flows out of the axon, causing the axon to return to its original negative resting membrane potential |
| All-or-none principle | Action potentials follow this principle, meaning they are irreversible and are long-distance signals |
| Refractory period | the time when it is difficult to elicit another action potential |
| Saltatory conduction | occurs very fast due to insulated current, action potentials are only generated at node of Ranvier |
| Continuous conduction | occurs slowly because each consecutive region of the membrane must be depolarized to generate an action potential |
| Synapse | where a neuron meets its target cell |
| Electrical synapses | occur between neurons whose axolemmas are electrically joined via gap junctions |
| Chemical synapses | these rely on neurotransmitters to send signals |
| Presynaptic neuron | triggers exocytosis of neurotransmitters stored in synaptic vesicles |
| Postsynaptic neuron | this is where the neurotransmitters bind to in order to cause a local postsynaptic potential |
| Excitatory postsynaptic potential (EPSP) | neuron may be depolarized |
| Inhibitory postsynaptic potential (IPSP) | neuron may be hyperpolarized |
| Neural integration | process of putting together the excitatory and inhibitory stimuli that determine whether a neuron will or won't fire an action potential |
| Summation | combines local postsynaptic potentials |
| Temporal summation | a single presynaptic neuron is fired at a rapid pace |
| Spatial summation | multiple presynaptic neurons fire simultaneously |
| Two descriptions of a neurotransmitter | excitatory and inhibitory |
| Excitatory neurotransmitter | generally induces EPSPs |
| Inhibitory neurotransmitter | generally induces IPSPs |
| What is acetylcholine (ACh) degraded by? | acetylcholinesterase |
| Types of catecholamines | norepinephrine, dopamine, and epinephrine |
| Types of biogenic amines | serotonin and histamine |
| Glutamate | the major excitatory neurotransmitter in the brain |
| GABA and glycine | the major inhibitory neurotransmitters in the CNS |
| Neuronal pools | allows for higher mental activity within the CNS |
| Input neuron | presynaptic neuron that initiates the series of signals in a neuronal pool |
| Neural circuit | the connections between neuronal pools |
| Diverging circuit | one or more input neurons that contact an increasing number of postsynaptic neurons |
| Converging circuit | signals from multiple neurons converge onto one or more final postsynaptic neuron |
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