Exam 3: Ch. 10-15 Flashcards
Fascia
A band or sheet of connective tissue beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs
Made primarily of collagen
Muscle Fascicle
A bundle of skeletal muscle fibers surrounded by perimysium
What are the three types of interstitial connective tissues found in muscles
Epimysium - Surrounds the entire muscle
Perimysium - Surrounds bundles of muscle fibers
Endomysium - Surrounds individual muscle fibers
Organization of muscle fibers (different types of muscles)
Fusiform - Spindle-shaped muscles that are tapering on both ends
Parallel - Characterized by fascicles that run parallel to one another. The contraction of a parallel muscle is similar to the contraction of a single muscle fiber
Triangular - A flat muscle with a broadband origin and a narrow point of insertion. Shaped like a paper fan
Unipennate - A pennate muscle in which the muscle fibers or fascicles are all on one side of the tendon
Bipennate - A pennate muscle with two rows of muscle fibers facing in opposite diagonal directions with a central tendon, similar to a feather. Allows for lots of power but less ROM
Multipennate - A pennate muscle with fibers arranged at many different angles in relation to the axis of force generation
Circular - Muscles that typically encircle an orifice or object
What is an example of a fusiform muscle?
Biceps Brachii
What is an example of a parallel muscle?
Rectus Abdominis
What is an example of a triangular muscle?
Pectoralis Major
What is an example of a unipennate muscle?
Palmar Interosseous
What is an example of a bipennate muscle?
Rectus Femoris
What is an example of a multipennate muscle?
Deltoid
What is an example of a circular muscle?
Orbicularis Oculi
Beyond movement, what benefits do humans get from facial muscles?
Non-verbal communication (facial expressions)
Emil Heinrich Du Bois-Reymond
Founder of modern electrophysiology in muscle and nervous tissue
Developed a way to demonstrate the Neuromuscular Junction
Controversy with “Frankenstein” because of the electrical current used to manipulate muscles
Within a muscle cell (fiber) what are the two types of fibers that compose the cell and give it striations?
Actin Fibers - Thin filaments
Myosin Fibers - Thick filaments
What is a unique feature of muscle cells?
Multiple nuclei are present because individual precursor cells have fused together. The existence of multiple nuclei, however, is very beneficial because it enhances protein organization and production within the cell.
Within a muscle cell, what is the function of Dystrophin?
Dystrophin is a protein that connects the border of the thick and thin filaments with the PLB to allow contraction of the entire cell rather than just the filaments.
Muscular Dystrophy
People with muscular dystrophy have developed deficits related to dystrophin protein development, presence, or function.
It causes weakness in the ability to contract muscle tissue, if the ability is present at all
H-Zone
The space between columns of actin fibers
Z-disc
The space where two columns of actin fibers connect
I-band
The space between columns of myosin fibers
A-band
The region that represents the span of a myosin fiber columns
M-line
Represents architectural fibers that position and arrange the myosin fibers
Titin Filaments
Elastic filaments that allow the distal ends of the myosin to connect to the Z-disc
Level of Organization for Muscles (Large - Small Structures)
Largest
- Muscle
- Muscle Fascicles
- Muscle Fibers
- Myofibril
- Muscle Filaments
Smallest
Components of Myosin Filaments
Head - Each myosin molecule has two heads
Flexible Hinge Region - Each tail has a flexible region just before the head that allows the heads to bend and reach toward the actin filament
Tail - Each myosin molecule has two tail regions that twist together
Components of Actin Filament
Actin Beads - Two separate strands of actin beads wrap around each other to form a strand of the actin filament.
Tropomyosin - Spaghetti-like strands of binding protein that organize actin beads into a strand
Troponin Complex - Molecules that hold the position and integrity of both the actin beads and the tropomyosin.
What happens to the H-zone during muscle contraction?
The H-zone is eliminated as the columns of myosin and actin filaments are brought closer together
Neuromuscular Junction (NMJ)
A living tissue connection between the nervous system and the muscular system
Structure of the NMJ
The distal ends of a neuron called the AXON TERMINALS, come into contact with a muscle fiber and release a chemical signal called a NEUROTRANSMITTER that chemically stimulates action at the site of contact.
Acetylcholine
The primary neurotransmitter for NMJs formed with skeletal muscle
Sarcoplasmic Reticulum
The membranes that surround myofibrils
Structures of the Sarcoplasmic Reticulum
T-tubule & Terminal Cistern - Both structures are important in regard to the effects of the neurotransmitters released by the NMJ. The T-tubule is a thinner band running perpendicular to the myofibrils and the Terminal Cisterns are the tissues surrounding the T-tubules.
Process of chemical stimulation by the NMJ
- Action potential arrives at the axon terminal
- Voltage-gated Calcium channels open, allowing Ca2+ to enter the axon terminal
- Ca2+ entry causes Acetylcholine (ACh) to be released from synaptic vesicles via exocytosis
- ACh diffuses across the synaptic cleft and binds to receptors on the sarcolemma
- ACh binding opens ion channels in the receptors that allow both Na+ ions to enter and K+ ions to exit the muscle fibers.
- ACh effects are terminated once it breaks down in the synaptic cleft and diffuses away from the NMJ
Latent Period
The period of time between when the stimulus is received and when the muscle begins to generate tension.
How does Ca2+ affect muscle fibers & contraction?
Ca2+ binds to the Troponin Complex on the actin filament, causing it to move out of the way so that the Head of the myosin fiber can latch onto the myosin binding site of the actin bead
How does the Myosin Head attach to the Actin Bead?
When the Myosin Head has a Hydrolyzed ATP molecule (ADP + P) attached to it, it is in its high-energy conformation and thus cocked into a position where it can attach.
The ATP molecule then dephosphorylates (releases P and becomes ADP), producing energy used to contract the muscle. After contraction, the ADP is released, and the Myosin Head receives another ATP molecule, weakening the link between filaments
The new ATP molecule is split into ADP & P and the process can occur again.
Period of Contraction
The period of time when myofibrils are actively contracting.
On a graph, it is the portion where the percentage of muscle contraction begins until it reaches its peak.
Period of Relaxation
The period of time when muscle myofibrils are relaxing/elongating
On a graph, it is the portion where the percentage of muscle contraction is at its peak until it reaches zero
How does muscle size impact the periods of contraction & relaxation?
Smaller muscles have fewer muscle cells, thus they respond more rapidly and take less time to return to zero percentage of contraction.
Larger muscles have more fibers to accommodate for, thus it takes more time to reach peak contraction and more time to return to zero percentage of contraction.
Levels of NMJ muscle stimulation
Low Stimulus Frequency - Produces a muscle twitch, allowing the muscle to fully relax before stimulating again
Muscle Summation (Incomplete Tetanus) - There is not enough time between stimuli for the muscle to fully relax, resulting in a wavering, but ever rising, amount of muscle tension
Tetanus (Complete/Fused Tetanus) - Stimuli are received so rapidly that the muscle reaches a point of maximal contraction and will stay “locked” in peak contraction until stimuli are no longer present at the NMJ
Tetanus (disease)
Commonly called “lockjaw”, Tetanus is a serious infection caused by a bacterium, which causes the production of a toxin that affects the brain and nervous system, leading to constant muscle contracture.
Severe, full-body tetanus can occur if untreated, leading to death by asphyxiation
Types of Contraction
Isotonic Contraction - The muscle visibly changes in length while producing tension
Isometric Contraction - The muscle does not visibly change in length, though tension is still produced. This is due to the load being too heavy for the muscle to move.
Slow Oxidative Muscle Fibers
Also called Slow Twitch fibers, they contain a high number of mitochondria, thus they can continuously generate ATP energy for long-term use.
Slow Oxidative Fibers tend to function aerobically and are fatigue resistant
Mitochondria are large and abundant
Capillaries are also abundant
Red in color
Chicken legs are “dark meat” because they are SO muscles used for everyday walking or running.
Fast Glycolytic Muscle Fibers
Also called Fast Twitch fibers, they have fewer and smaller mitochondria. They do, however, store high-energy molecules called glycogen, which can be quickly converted to ATP for use in contraction.
Fast Glycolytic Fibers tend to function anaerobically and fatigue easily once glycogen stores are depleted. FG fibers are faster due to the fact that glycogen can be converted into ATP (glycolysis) faster than mitochondria can produce ATP.
Mitochondria are smaller and less abundant
Capillaries are not abundant
White/Pale in color
Chicken breasts are “light meat” because chickens only flap their wings occasionally and for a short duration (until glycogen is depleted)
How to increase Contractile Force (strength)?
- Use larger muscle groups because more fibers = more strength generated
- Use weight training to increase the size of the muscle fibers because larger fibers = more strength
- Use tetanic contractions (hold muscles in stationary maximal tetany) via yoga or other means
- Use stretching exercises before an activity to give you greater strength during the activity because stretching helps muscles attain their greatest possible lengths.
How to increase Contractile Velocity (speed)?
- Use lower-weight, repetitive load-bearing training to facilitate contractile velocity
- Exercises used for increasing contractile velocity will target fast glycolytic (fatigable) fibers
How to increase Contractile Duration?
- Use lower-weight, repetitive load-bearing training to facilitate contractile duration
Exercises used for increasing contractile duration will target slow oxidative (fatigue-resistant) fibers
Types of Muscle Cells
Skeletal - Attached to bones or skin, obvious striations, multinucleate
Cardiac - In the walls of the heart, branching chains of cells, uni- or binucleate, obvious striations, and intercalated discs
Smooth - In the walls of hollow visceral organs (other than the heart), present airways, large arteries, single-celled uninucleate structures with no striations or intercalated discs
Myasthenia Gravis
An autoimmune disorder where the immune responses of the body begin to attack the NMJs, thus damaging the brain and nervous system. This disorder inhibits the regulation and control of muscular system cells
To diagnose, clinicians often have patients look upward for a period of time. If the patient has this disorder, involuntary drooping of one eyelid is often observable.
Santiago Ramon Y. Cajal
The founding scientist in the modern approach to neuroscience. Received the Nobel Prize in 1906 with Camillo Golgi.
What are the major subdivisions of the Nervous System?
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
What are the structures that make up the CNS?
The brain and the spinal cord
What are the subdivisions of the PNS?
Afferent (sensory) Division - Acquires information from our environment such as external senses (touch, smell, sight, hearing, taste) as well as internal senses (baroreceptors regulating blood pressure)
Efferent (motor) Division - Relays decisions from the CNS out to structures to cause actions (signals to muscles to contract)
How do the PNS divisions and the CNS work together?
The Afferent System gathers information about the environment (seeing things, hearing things, etc.). Those signals are then sent to the CNS to be integrated and make decisions. Signals then go out to the Efferent System and an action is made.
What are the subdivisions of the Efferent Nervous System?
Autonomic Nervous System (ANS) - The portion of the efferent nervous system that is autonomous (heartbeat)
Somatic Nervous System - The portion of the nervous system that is consciously controlled to do work (skeletal muscles)
What are the subdivisions of the Autonomic Nervous System?
Sympathetic Division - The “Fight or Flight” division that is integral for stress responses. This division drives us to take action (running away from a bear in the forest)
Parasympathetic Division - The “Resting and Digesting” division that is prominent in periods of lower stress. “Housekeeping & Maintenance” during rest (brings feelings of relaxation).
Parts of a Neuron Cell
Dendrite - The small branches coming off of the cell body that typically receives a stimulus or message
Cell Body (Soma) - The portion of the neuron that is most typically like other cells. It contains the nucleus, most of the cytoplasm, and most of the organelles.
Axon - The portion of the neuron that typically relays messages away from the cell body and toward the next cell in a sequence of communication (the next neuron, NMJ, muscle fiber, etc.)
Axon Terminal - The distal portion of a neuron that converts the “electrical” signal within a neuron into a “chemical” signal via the release of neurotransmitter chemicals
Synapse - The absence of structure. The space between an axon terminal and the next cell in the sequence (the next neuron’s dendrite, NMJ, etc.)
Other cells of the Nervous System
Astrocytes - Cells that help to connect neurons and blood vessels together. They are star-shaped cells that allow nourishment and waste products to move into or out of the neuron.
Microglial Cells - Part of the body’s immune response, they monitor for and protect organs (mostly the brain) from diseases and infections
Ependymal Cells - Cells that produce Cerebrospinal Fluid (CSF). They are found in the ventricles of the brain and fill the ventricles with CSF. These cells have cilia on their surfaces to help move CSF around the structures of the CNS.
Oligodendrocytes - Cells that produce myelin and are found in the CNS
Schwann Cells - Cells that produce myelin and are found in the PNS
What is the role of myelin in the Nervous System?
When myelin is present around an Axon, the rate at which messages travel through the neuron. The more myelin present, the faster the message is conducted.
Chemically Gated Channels
Receptor Proteins in the PLB of a cell open or close in the presence of a neurotransmitter chemical signal being bound to the protein.
Voltage-Gated Channels
Transmembrane Proteins in the cell membrane of a neuron that react (open & close) in response to the membrane potential across the PLB. When the outside of a cell is net positive and the inside is net negative, the protein channel is closed. When the charges flip, the protein channel opens and allows molecules to pass through.
What is the role of the Sodium-Potassium Pump in neurons?
The sodium-potassium pump uses active transport to expel excess sodium and bring in potassium that has leaked out. It does this to maintain a neuron’s ion ratios
What is Resting Membrane Potential?
Resting Membrane Potential is the measure of ion differences across the PLB when no messages are being carried through a neuron
Depolarization
The term used when the cell membrane potential becomes less electronegative (goes toward zero)
Hyperpolarization
The term used when the cell membrane potential becomes more electronegative (goes away from zero)
What are the steps of action potential generation?
- Resting State: The state of a neuron when it is not carrying a message. Both sodium and potassium voltage-gated channels are closed
- Depolarizing Phase: As the stimulus passes through the neuron, membrane potential quickly rises to its action potential (the peak on the graph). The sodium channels open.
- Repolarizing Phase: The stimulus has passed and action potential begins to decline. The sodium channels begin to close and the potassium channels open, allowing K+ to flood out, changing membrane potential.
- Hyperpolarization: The neuron is resetting. The K+ channels remain open so that the cell can reach equilibrium. The Na+ channels are resetting to start the cycle over.
How does the voltage (stimulus) affect action potential?
If the voltage (stimulus) fails to meet the threshold, the neuron is insufficiently stimulated and no action potentials are generated.
If the voltage is medium in strength, a few action potentials will be generated at a slow rate.
If the voltage is great in strength, many action potentials are generated very rapidly
Saltatory Conduction
The process of a message “skipping” down the axon of a neuron, only slowing in unmyelinated areas
Nodes of Ranvier
Unmyelinated patches of an axon where signal speed slows momentarily. They regenerate action potential in the neuron. This occurs because the unmyelinated patches allow for ion exchange, meaning some K+ ions leave and some Na+ ions enter.
Types of Synapses
Axodendritic Synapse - The axon terminal of one neuron is communicating with the dendrite of another neuron
Axoaxonic Synapse - The axon terminal of one neuron is communicating with the axon of another
Axosomatic Synapse - The axon terminal of one neuron is communicating with the cell body (soma) of another
How are neurotransmitters released from the axon terminal?
Voltage-Gated Calcium channels are opened in the presence of neurotransmitters, allowing Ca2+ to flood into the axon terminal. This influx of calcium drives the vesicles full of neurotransmitters to release their contents into the synapse via exocytosis.
What are the different types of responses cells can have at the synapse?
Excitatory Post Synaptic Response (EPSP) - The next cell becomes excited and membrane potential increases
Inhibitory Post Synaptic Response (IPSP) - The next cell becomes quieted and membrane potential decreases. This occurs when an inhibitory neuron releases a neurotransmitter that inhibits the stimulus neuron’s ability to release its own neurotransmitter
Facilitating Neuron
A neuron that releases its neurotransmitter, generating an EPSP in the stimulus neuron and boosting the latter to release an adequate amount of neurotransmitter to that it can generate an EPSP with the response neuron
Types of Spinal Nerves
Cervical
Thoracic
Lumbar
Sacral
Coxygeal
Meninges of the Spinal Cord
Superficial
- Dura Mater
- Arachnoid Mater
- Pia Mater
Deep
Fetal Development of the Spinal Cord
19 days - The Neural Plate is present, bordered by the Neural Crest
20 days - The Neural Plate has begun to fold, forming the Neural Fold and the Neural Groove
22 days - The Neural Fold & Groove fold further
26 days - The Neural Fold & Groove become the Neural Tube, the Neural Crest runs along the dorsal aspect of the tube
Spina Bifida
A defect that occurs at the caudal end of the neural tube where the Neural Tube doesn’t fully close. This disease may experience an array of locomotor deficits (as simple as an uncoordinated gait or as complex as paraplegia)
Pregnant women are often prescribed Folic Acid supplements because low folic acid levels increase the risk of incomplete spinal cord development
How does spinal cord damage impact bodily function?
If an individual experiences a severing of the spinal cord, any nerves below the point of severance will no longer function
Paraplegia
Paraplegia is a spinal cord injury that results in the loss of the ability to control the legs. Any severing of the spinal cord below T2 will result in paraplegia, however, the lower the severance is, the less the total deficit will be.
Quadriplegia
Quadriplegia is a spinal cord injury that results in the loss of ability to control both the arms and legs of the body. Any severing of the spinal cord above the T1 region will result in quadriplegia. The higher the point of severance, the more severe the loss of mobility will be.
Anencephaly
Anencephaly is the absence of a major portion of the brain that occurs during embryonic development. This disorder is similar to Spina Bifida, but instead of the caudal end of the Neural Tube developing incorrectly, the cephalic end doesn’t close.
What are the 5 steps of development in the human brain?
- Neural Tube
- Primary Brain Vesicles
- Secondary Brain Vesicles
- Adult Brain Structures
- Adult Neural Canal Regions
What are the Primary Brain Vesicles?
Prosencephalon
Mesencephalon
Rhombencephalon
What are the Secondary Brain Vesicles?
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
Wilder Penfield
Physician and Neuroscientist who mapped the brain in what became the “homunculus”
Sigmund Freud
Founder of the psychoanalytic theory of personality development, which argued that personality is formed through conflicts among three fundamental structures of the human mind: the id, ego, and superego.
How does the parasympathetic nervous system continue to function when the sympathetic nervous system has lost its control in a spinal cord injury?
The parasympathetic nervous system contains nerves that have a point of entry closer to the brainstem, thus, if the spinal cord is damaged, the parasympathetic system can still function because the nerves originate above the point of injury.
Referred Pain Sites
Referred Pain Sites are areas or regions of the body that lack pain receptors and will send signals to other regions of the body that do have pain receptors.
An example of this would be how an individual suffering from a heart attack will feel pain in their left pectoral region as well as the medial aspect of their left arm. The heart has no pain receptors so it sends signals to the body causing the sensation of pain in those areas. In women, pain from a heart attack is often times felt in the cheeks of the face.
Marshall Hall
An English physiologist who first advanced the theory of how reflex arcs worked.
