chapter 9, Chapter 11 Biology Exam, Physiology Review--Muscular System, Chapter 9: Skeletal Muscle Tissue Learning objectives 9.1-9.15 &22.3, Chapter 12, A&P muscle tissues

What is the byproduct of anaerobic respiration

lactic acid

Which of these would not lead to increased oxygen consumption?

lactic acidosis

The increase in muscle tension that is produced by increasing the number of active motor units is called

recruitment

What is a fascicle

several muscle fibers bundled into a cable like structure

Identify the three types of muscle tissues

skeletal muscle, cardiac muscle, and smooth muscle

The narrow space between the synaptic terminal and the muscle fiber is the

synaptic cleft.

two subunits of myosin

tail (wound with other tails) and head (binding site to actin= cross bridge)

At the ends of the muscle the epi-, peri-, and endomysium come together to form the

tendon or aponeurosis

Within a resting skeletal muscle fiber, where is the greatest concentration of Ca2+? (Module 9.3C)

terminal cisternae of the sarcoplasmic reticulum

Identify three sources of stored energy utilized by muscle fibers. (Module 9.12B)

ATP, creatine phosphate, and glycogen

How would a drug that blocks Ach release affect muscle contraction?

Ach release is necessary for skeletal muscle contraction, because it serves as the first step in the process that enables the formation of cross-bridges in the sarcomeres. A muscle's ability to contract depends on the formation of cross-bridges between the myosin heads and actin myofilaments. A drug that blocks ACh release would interfere with this cross-bridge formation and prevent muscle contraction

Define gated ion channels

Active channels in the plasma membrane that open or close in response to specific stimuli

Describe the role of regulatory neurons

Facilitate or inhibit the activities of presynaptic neurons by affecting the plasma membrane of the cell body.

Module 9.10: Factors affecting peak tension production during the contraction of an entire skeletal muscle, explain the significance of the motor unit

Factors affecting peak tension: Amount of tension produced and total number of muscle fibers Motor units regulate tension produced

Which of the following statements is/are not true regarding human muscles?

Fast fibers are high in myoglobin.

Distinguish between fast axonal transport and slow axonal transport, and give examples of the different substances moved by each

Fast-occurs approx 400 mm per day(ex:vesicles, organelles, glycoproteins) Slow- occurs approx 0.1 mm- 3 mm per day(ex: enzymes, cytoskeletal components, axoplasm

What is meant by 'excitation-contraction'

First the heads must be cocked by ATP then pivoted by Ca ---excitation and contraction

Identify the 4 classes of neurotransmitters based upon chemical structure

Four classes of neurotransmitters based on structure: Acetylcholine (Ach): -can be excitatory or inhibitory. -found in both the CNS and PNS. -found at a neuromuscular junction. Biogenic Amines: -are derived from certain amino acids by the removal of a carboxyl group(-COOH) and the addition of another -functional group (e.g. an amine group). -contain a subgroup called catecholamines (norepinephrine, epinephrine, and dopamine). Amino acids: -are the building blocks of proteins but also chemical messengers. -Examples include glutamate, glycine, aspartate, and GABA (a modified amino acid). Neuropeptides: -are chains of amino acids, ranging from 2 to 40 amino acids. -Examples include natural opiates such as enkephalins and beta-endorphins.

What happens to the lactate produced by skeletal muscle during peak activity? (Module 9.13C)

Most of the lactate diffuses into the bloodstream and enters the liver where it is converted to pyruvate.

What factors account for the local currents associated with graded potentials?

Movement of sodium ions parallel to the inner and outer surfaces of the plasma membrane accounts for the local currents.

What types of organelles are specific to muscle cells and their functions

Muscle cells are full of organelles called mitochondria. Other organelles found in muscle cells are ribosomes and cytoskeleton. There is also both rough and smooth ER.

When do muscle fibers produce lactate? (Module 9.12C)

Muscle fibers produce lactate when there is a lack of oxygen.

Tetanus is most likely to result from which condition?

a deep puncture wound, such as that from a nail

Troponin

a globular protein that binds tropomyosin to G-actin and is controlled by Ca

Which of the following muscles would contract more forcefully?

a muscle receiving 20 to 25 action potentials per second

what is muscle fatigue?

a muscle's reduced ability to contract due to low pH (lactic acid buildup and its dissociation to lactate and a hydrogen ion), low ATP levels, or other problems

why does a muscle that has been overstretched produce less tension?

a muscles ability to contract depends on the formation of cross-bridges between myosin and actin. in a muscle that is overstretched, the myofilaments would overlap very little, so very few cross-bridges would form, making the contraction weak. If no myofilaments overlap no cross-bridges would form and no contraction occurs.

A single neural stimulation produces

a single contraction or twitch which lasts 7-100 msec

why would skeletal muscle fibers appear striated when viewed through a microscope?`

because z lines and thick filaments of the myofibrils within the muscle fibers are aligned

What do the tails of the myosin molecules do

bind to other myosin sub units

Describe how neurotransmitters are classified based upon function

direct response - neurotransmitter directly binds to the receptor on the target cell to cause opening of an ion channel indirect response - neurotransmitter binds to a receptor that activates the second messenger pathway involving G protein

Perimysium

divides the muscle into compartments called fascicles (contains blood vessels and nerves)

Individual muscle cells are surrounded by what connective tissue?

endomysium

muscle fibers are surrounded by:

endomysium and contain myofibrils

The dense layer of connective tissue that surrounds an entire skeletal muscle is the

epimysium

skeletal muscle surrounded by :

epimysium and contains muscle fascicles

Muscle fibers differ from "typical cells" in that muscle fibers

have many nuclei.

Each skeletal muscle fiber contains ________ myofibrils.

hundreds to thousands

Contrast an electrical synapse with a chemical synapse

in chemical synapses a neurotransmitter crosses a narrow synaptic cleft

Muscular force can be adjusted to match increased loads by

increasing the frequency of action potentials in motor neurons.

which type of muscle fibers would you expect to predominate in the leg muscles of someone who excels at endurance activities such as cycling or long distance running?

individuals that excel at endurance activities gave a higher than normal percentage of slow fibers. Slow fibers are better adapted to for endurance than fast fibers because fast fibers are less vascular and fatigue faster

Nebulin

is a protein strand that runs down the middle of the F-actin and holds it together

Tropomyosin

is a twisted strand that prevents actin/myosin binding. it covers the outside of the G-actin strands.

Aerobic endurance (prolonged aerobic activity)

is supported by mitochondrial activity, requiring oxygen and nutrients provided by circulating blood.

F-actin

is two twisted strands of G-actin that has active sites for myosin hookup

Where does the muscle get energy for sustained contractions

it must manufacture it from glycogen

myofibrils are surrounded by:

sarcoplasmic reticulum and contain sarcomeres

What is myosin action during contraction

1. interact with actin forming cross bridges 2. heads pivot causing contraction

Improvements in aerobic endurance result from:

1. repetitive training to alter the neural responses of fast fibers 2. cardiovascular training

Name the three types of muscle fibers

1. skeletal 2. smooth 3. cardiac

List the distinguishing features of glial cells

-(neuroglia) are found in the CNS and PNS and are capable of mitosis. -do not transmit nerve signals, but do assist neurons with their functions. -physically protect neurons. -nourish neurons. -guide migrating neurons during human development. -far outnumber neurons.

Describe the 3 basic anatomic features common to most neurons

-Cell body(soma) -Dendrites -Axon

Identify the structural components included in both the CNS and PNS

-Central Nervous system: Brain and Spinal Cord -Peripheral Nervous system: Nerves and Ganglion

Describe the 3 functions of the nervous system

-Collect information -Process and evaluate information -Initiate response to information

Describe the 5 distinguishing features common to all neurons

-Excitability -Conductivity -Secretion -Extreme longevity -Amitotic

Name and describe the 4 structural categories of neurons

-Multipolar: most common, many dendrites and one axon -Bipolar: one axon, one dendrite -Unipolar: a single, short neuron process that emerges from the cell body and branches like a "T" -Anaxonic- NO Axons, only dendrites

Describe how action potentials vary in frequency

-depends on the strength of stimulus -strength increases, frequency increases

Identify and describe the structures unique to neurons

-Perikaryon-Cytoplasm w/in cell body -Chromatophilic- free and bound ribosomes -axon hillock-triangular region of cell body -axoplasm-cytoplasm w/in an axon -axolemma-plasma membrane of axon -axon collaterals- side branches -telodendria- fine terminal extensions -synaptic knob-bulbs

Identify the 3 functional categories of neurons and where each is primarily located

-Sensory Neurons: Retina of eye, olfactory epithelium -Motor Neurons: motor output -Interneurons: entirely within CNS

Describe the 2 primary factors that influence the velocity of action potential propagation

-large diameter = less resistance = quick threshold value = faster propagation of action potential -myelination = saltatory ("skipping") conduction = faster propagation of action potential

Describe how acetylcholine functions as a neurotransmitter

1. ACh is synthesized from acetate and choline stored in the synaptic vesicles in the synaptic knob. 2. ACh is released from the synaptic knob via exocytosis into the synaptic cleft .3. Some ACh is immediately broken down into acetate and choline by the enzyme acetylcholinesterase (AChE), which resides in the synaptic cleft, and the choline is taken up into the synaptic knob from which it came where it can resynthesized into ACh. 4. Some ACh binds to receptors on the target cell and then dissociates. Upon dissociation, AChE breaks down the ACh as described in step 3.

Describe the events that occur when the propagated action potential reaches the transmission segment

1. Action potential reaches the synaptic knobs. 2. Voltage-gated Ca2+ channels open. 3. Ca2+ moves into the synaptic knobs down their concentration gradient. 4. Ca2+ binds to proteins of synaptic vesicles. 5. Vesicles fuse with the plasma membrane in the synaptic knob. 6. Neurotransmitter is released via exocytosis into the synaptic cleft. 7. Neurotransmitter molecules diffuse across the cleft and bind to protein receptors on another neuron or an effector (i.e. a muscle or gland).

Specify the functions of skeletal muscle tissue

1. Produce skeletal movement 2. Maintain posture and body position 3. Support soft tissue 4. Guard entrances and exists 5. Maintain body temperature 6. Store nutrient reserves

What does the amount of tension in a muscle fiber depend on

1. The number of pivoting cross-bridges 2 The fiber's resting length at the time of stimulation 3. The frequency of stimulation 4. Length Tension Relationship

What are the parts of the thick filaments (myosin)

1. Titin strands 2. Twisted myosin subunits 3. Myosin Molecule

What are the three layers of connective tissues in muscles

1. epimysium 2. perimysium 3. endomysium

Endomysium

surrounds individual muscle fibers

Module 9.8: Describe how muscle tension develops with respect to neural control and excitation contraction

1.) motor neuron stimulates through action potential 2.) ACh is released into the synaptic cleft, leading to excitation. 3.) Calcium Ions are released 4.)Ca 2+ bind to troponin 5.) sarcomeres shorten pulling fiber ends together 6.) tension is produced

How many ATPs does anaerobic respiration produce

2 per glucose molecule

How many ATPs does aerobic respiration produce

34 per glucose molecule

What is the normal resting sarcomere length

75-130% of optimal length

Aerobic metabolism normally provides ________ percent of the ATP demands of a resting muscle cell.

95

How is ATP recycled

ATP is degraded to ADP and a free phosphate to utilize the kinetic energy of the electron that holds it together then uses energy from the sugar to put it back together.

The region of the sarcomere containing the thick and thin filaments is the

A band.

Define graded potential

A change in the membrane potential that cannot spread far from the site of stimulation.

Define motor unit. (Module 9.10B)

A motor unit is a motor neuron and all the muscle fibers that it controls.

why would a sprinter experience fatigue before a marathon runner would?

A sprinter requires large amounts of energy for short bursts of activity. To supply this energy, the sprinter's muscles rely on anaerobic metabolism. Anaerobic metabolism is less efficient in producing energy than aerobic metabolism, and the process also produces acidic wastes; this combination contributes to muscle fatigue.

Define tendon and aponeurosis. (Module 9.2A)

A tendon is a bundle of collagen fibers that connects a skeletal muscle to a bone, whereas an aponeurosis is a broad collagenous sheet that connects skeletal muscle to a broad area on one or more bones.

sarcolemma

surrounds the sarcoplasm

What chemicals are used in muscle contraction

ACh, Ca, Na, ATP

A two-second duration of isometric tetanic contraction is supported by which energy source alone?

ATP

What is the energy molecule of the cell

ATP

Anaerobic endurance :

Anaerobic activities (e.g. 50 meter dash or weightlifting) use fast fibers, which fatigue within about 2 minutes of strenuous activity. Frequent, brief, intensive workouts stimulate muscle hypertrophy, which improves anaerobic endurance.

Classify neurons based on their function

As sensory neurons, interneurons, or motor neurons

Which glial cell protects the CNS from chemicals and hormones circulating in the blood?

Astrocytes protect the CNS

Describe the structure and function of the 4 types of glial cells w/in the CNS and the 2 types of glial cells w/in the PNS

CNS: 1. Astrocytes- help form the blood brain barrier 2. Ependymal- line the internal cavities of the brain (ventricles) and spinal cord (central canal). -form the choroid plexus 3. Microglia- phagocytic immune cells 4. Oligodendrocytes- responsible for the myelin sheath on the CNS neurons. PNS: 1. Satellite cells-physically separate cell bodies from the surrounding interstitial fluid (ECF). -regulate the continuous exchange of nutrients and waste. 2. Neurolemmocytes- aka Schwann cells and ensheath PNS axons to form the myelin sheath.

Describe the structure of a nerve, including the 3 layers of connective tissue wrappings

Cable-like bundle of parallel axons that are components of PNS. Epineurium- thick layer of dense irregular CT that encloses entire nerve perineurium-layer of dense irregular tissue that supports blood vessels and wraps fascicles endoneurium-layer of areolar connective tissue that surrounds an individual axon in a myelinated neuron and electrically insulates each axon.

What event initiates the contraction cycle?

Calcium ions arrive within the zone of overlap.

Describe the essential structural and functional differences between a chemical synapse and an electrical synapse

Chemical- composed of a presynaptic neuron, which is a signal producer, and a postsynaptic neuron, which is the signal receiver or target. Electrical- composed of a presynaptic neuron and a postsynaptic neuron physically bound together.

Identify the three types of gated ion channels, and state the conditions under which each operates

Chemically gated ions operate when they bind specific chemicals such as ACh. Voltage gated ion channels operate in response to change in the membrane potential. Mechanically gated ions operate in response to physical distortion of the membrane surface.

Compare concentric and eccentric contractions. (Module 9.11B)

Concentric contractions occur when the muscle tension exceeds the load, and the muscle shortens. Eccentric contractions occur when the muscle tension is less than the load, and the muscle elongates.

Explain propagation of an action potential in both myelinated and unmyelinated axons (conductive segments of neurons)

Continuous conduction occurs in unmyelinated axons and involves the sequential opening of voltage-gated Na+ channels and voltage-gated K+ channels located within the axon plasma membrane. Saltatory conduction occurs in myelinated axons. Here action potentials do not occur in the myelinated regions, rather they occur at neurofibril nodes in between the myelinated regions of axon.

Define continuous propagation and saltatory propagation

Continuous- propagation of an action potential alone an unmyelinated axon. Saltatory- the relatively rapid propagation of an action potential between successive nodes of a myelinated axon.

a single thin filament contains proteins:

F-actin, tropomyosin, and troponin

Identify the 4 different types of neuronal pools, and explain how they function (converging and diverging circuit function)

Converging Circuit- postsynaptic neuron receives input from several different presynaptic neurons(ex. produce saliva) Diverging Circuit- presynaptic neuron spreads information to many postsynaptic neurons(ex.stimulates muscles while walking) Reverberating Circuit- uses feedback (ex. breathing while asleep) Parallel-after-discharge Circuit- input follows several pathways to a single post-synaptic neuron(ex. high order thinking)

Describe depolarization, repolarization, and hyerpolarization

De- a shift form resting membrane potential toward positive value. Re- return of depolarized membrane potential Hyper- a shift from the resting membrane potential toward negative value.

What effect would decreasing the concentration of extracellular potassium ions have on the resting membrane potential of a neuron?

Decreasing the concentration of extracellular potassium ions would cause more potassium ions to leave the cell through potassium leak channels

Discuss the different mechanisms for removing neurotransmitter from the synaptic cleft.

Degradation: when the neurotransmitter is chemically inactivated in the synaptic cleft. Reuptake: when the neurotransmitter is reabsorbed by a neurotransmitter transport protein in the membrane of the presynaptic neuron. (i.e. The neurotransmitter molecules are "recycled" and "repackaged" into vesicles.)

Explain how the resting membrane potential is established and maintained in neurons

Dependent on the distribution of the aforementioned ions and other substances such as negatively charged phosphates and negatively charged proteins -negatively charged proteins have a higher concentration in ICF -K+ diffusion is the most important factor in establishing a specific value in RMP

List the events involved in the generation of an action potential

Depolarization, inactivation of voltage gated potassium ion channels, and closing of voltage gated potassium ion channels

Describe and graph an action potential. Use depolarization and Repolarization in your explanation

Depolarization: Na+ flows inward through voltage-gated Na+ channels. The inside of the axon becomes positive. Repolarization: K+ flows outward through voltage-gated K+ channels. The membrane returns to the negative RMP.

Which of the following is correct regarding muscle fatigue and recovery?

During the recovery period, lactate can be recycled back to pyruvate.

Define excitatory postsynaptic potential(EPSP) and inhibitory postsynaptic potential (IPSP)

EPSP- a graded depolarization of a postsynaptic membrane by a neurotransmitter released by a presynaptic cell IPSP-a graded hyperpolarization of a postsynaptic membrane after the arrival of a neurotransmitter

Name the neuroglia of the CNS

Epydymal cells, microglia, astrocytes, and oligodendrocytes

Compare and contrast the action of excitatory and inhibitory neurotransmitters in developing both excitatory and inhibitory post-synaptic potentials(graded potentials) in the receptive segment

Excitatory postsynaptic potential (EPSP): - results in depolarization. -more positive -more Na+ in the K+ out Inhibitory postsynaptic potential (IPSP): -results in hyperpolarization. -more negative -more K+ out than Cl- moves in

Compare F-actin with G-actin. (Module 9.4A)

F actin is a twisted strand made up of two rows of G actin subunits where myosin heads can bind.

Define a post-synaptic potential

Graded potentials that occur in postsynaptic neurons -can be excitatory or inhibitory

Compare graded potentials and action potentials

Graded potentials: -Generated at Receptive Segment -Chemically Gated Na+, K+, and Cl- Channels -Depolarization OR Hyperpolarization Action potentials: -Generated at Initial Segment and Propagated down Conductive Segment -Voltage-Gated Na+ and K+ Channels -Depolarization Followed by Repolarization

Compare a graded potential with an action potential

Graded- temporary, localized changes Action- generated and begin in one location

Identify the criteria used to distinguish the groups of nerve fibers

Group A: -as fast as 150 meters per second -large diameter -myelinated -most somatic sensory neurons from receptors to CNS -all somatic motor that extend from CNS to skeletal muscles Group B: -as fast as 15 meters per second -small in diameter -unmyelinated -sensory visceral and motor autonomic neurons -somatic sensory neurons from receptors of skin to CNS Group C: -as fast as 1 meter per second -small in diameter -unmyelinated -sensory visceral and motor autonomic neurons -somatic sensory neurons from receptors of skin to CNS

G-actin

Has active site that binds thick filaments

The region of the sarcomere that always contains only thin filaments is the

I band.

What would happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to calcium ions?

If the sarcolemma of a resting skeletal muscle suddenly became permeable to calcium ions, the cytosolic concentration of calcium ions would increase, and the muscle would contract. Also because of the amount of calcium ions in the cytosol must decrease for relaxation to occur, the increased permeability of the sarcolemma to calcium ions might prevent the muscle from relaxing completely.

Which neuroglia appear in increased​ numbers in a person with a brain infection?

In a person with brain infection

In which part of a neuron does Walerian degeneration occur?

In axons of the PNS neurons

Module 9.7: Role of ATP in muscle contractions and its steps

In resting sarcomere, myosin heads are charged and cocked, Cocking requires ATP 1.) contraction cycle: Calcium ions arrive 2.) CA ions binto to troponin, 3.) Myosin heads bind to active sights and form cross bridges 4.) Myosin head pivot towards the M line (Power stroke) 5.) Active sight is now exposed 2.) Myosin reactivates when the free myosin head splits ATP and ADP and P

How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?

It would cause spastic paralysis (muscles are contracted and unable to relax).

What does the calcium ion do in a muscle contraction

It binds to a receptor on troponin causing the troponin/tropomyosin complex to shift and expose the 'active site'

What does the Na do after it is released across the sarcolemma

It causes an action potential to travel across the sarcolemma and into the t tubules to the triads

How does the action potential cause contraction at the triads

It causes the release of Ca into the muscle fiber which pivots the myosin head

Which of the following is not true of the muscular system?

It depends upon the cardiovascular system to provide the hemoglobin stored in slow muscle fibers.

How is the H band distinguished from the other prominent structural features of the sarcomere?

It is a lighter region that contains thick filaments, but no thin filaments.

What happens to the ACh that was released

It is quickly metabolized by ACh-esterase

How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle?

It would cause flaccid paralysis (muscles are relaxed and unable to contract).

Where does the muscle get energy to start

It's stored

What happens at the sodium-potassium exchange pump?

Maintains the cells resting membrane potential by ejecting 3 sodium ions from the cell for every 2 potassium ions it recovers from extracellular fluid

Are unipolar neurons in a tissue sample of the PNS more likely to have a sensory or a motor function?

More likely to have a sensory function.

Why is a CNS neuron not usually replaced after its injured?

Most CNS neurons lack centrioles which organize the microtubules of the spindle apparatus during mitosis, so these cels cannot divide and replace themselves

Define muscle hypertrophy and muscle atrophy. (Module 9.15A)

Muscle hypertrophy is an increase in the size of the muscle cells and muscle atrophy is a decrease in the size of the muscle cells.

What event must occur in the postsynaptic cell before it generates an action potential?

Must reach threshold to generate an action potential

Define myelination, and describe the composition and function of the myelin sheath

Myelination-the process by which a part of an axon is wrapped with myelin. -myelin is an insulated covering around an axon -repeating concentric layers of the plasma membrane of glial cells -contains a large portion of lipids to give it a glossy look

Module 9.2: Skeletal muscle development

Myoblasts form multinucleated cells that develop into muscle fibers. Sarcolemma- plasma membrane Sarcoplasm- cytoplasm

Module 9.3: Identify the structural components of a sarcomere

Myofibril- make up the sarcoplasm- cause striations Myofilaments- Bundles of proteins in myofibrils (thin filaments -actin, Thick filaments-myosin) Sarcomeres: repeating contractile unites in myofilaments H-band- lighter region, contains thick filaments M-line connects central portion of each thick filament A band- Dense region of the sarcomere that contains thick filaments I band- Contains thin filaments z band- mark boundary between adjacent sarcomeres- consist of actions Transverse tubules extend the sarcoplasm at right angles to cell surface zone of overlap- thin filaments are arranged in a 6-1 ration around each thick filament Sarcoplasmic reticulum- forms a tubular network around each individual myofibril. Terminal cisternae: SR enlarge, fuse, and form expanded chambers

When a skeletal muscle fiber contracts, which of the following does not occur?

Myosin and actin filaments decrease in length.

List the channels and pumps that are located along the entire neuron, and identify the general function of each

Na+/K+ exchange pumps- Na+ leak channels- K+ leak channels-

Define neuromodulation, including its function in facilitation and inhibition.

Neuromodulation-the release of chemicals from cells that locally regulate or alter the response of neurons to neurotransmitters. -Facilitation: when there is a greater response from the postsynaptic neuron because of the release of neuromodulators. -Inhibition:when there is less response from the postsynaptic neuron because of the release of neuromodulators.

module 9.6:Identify components of neuromuscular junction and summarize events involved in the control of skeletal muscles

Neuromuscular junction- Specialized sight that controls skeletal muscle fibers made up of: axon terminal- lies near the motor end plate motor end plate - contains membrane receptors that bind ACh synaptic cleft- A narriw space that separates axon from opposing motor and plate motor neuron- a nerve cell that propagates electric signals 1.) motor neuron stimulates releasing ACh 2.) Calcium ions flood into sarcomeres contracting the muscle 3.) Action potential travels along axon 4.) when action potential reaches neurons axon terminal exocytosis occurs 5.) Ach diffuses across synaptic cleft binding to ach repetors, Sodium ions rush into sarcoplasm 6.)Inrush of sodium ions generates action potential in the sarcolemma. ACH either diffuses or inactivates ACh receptor sites

Classify neurons based on their structure

Neurons are structurally classified as anaxonic, bipolar, unipolar, or multipolar

Define resting membrane potential and state its typical value for neurons

Neurons membrane potential is -70mV

Does the A band change during contraction

No. The A band remains the same while the Z lines are pulled to the middle (M line)

Distinguish between the myelination process carried out by neurolemmocytes in the PNS and by oligodendrocytes in the CNS

PNS: -completed by neurolemmocytes in the PNS -only occurs in 1 mm sections around the axons with gaps in between each section. -pushes nucleus to outside CNS: -occurs via an oligodendrocyte, but the axons are myelinated many at a time, rather than one at a time -No neurilemma is formed -Neurofibril nodes (Nodes of Ranvier) are located between adjacent oligodendrocyte wraps

Compare presynaptic and postsynaptic cells.

Presynaptic- usually a neuron Postsynaptic- can be a neuron or other type of cell such as a skeletal muscle fiber or gland cell.

Module 9.1: Functions of skeletal muscle

Produce skeletal movement Maintain posture Thermoregulation Support soft tissue Guard body entrances Provide Nutrient reserve

Distinguish between a pump and a channel, and describe the 3 specific states of a voltage-gated channel

Pumps- move substances across the plasma membrane UP the concentration gradient(low to high) Channels- move the substance DOWN it's concentration gradient (high to low) 3 states: Resting- the inactivation gate is open -the activation gate is closed -Entry of sodium into the cell is prevented Activation- inactivation gate is open -activation gate is open in response to a voltage change - Sodium is moving through the channel and into the cell Inactivation- activation gate is open -inactivation gate is temporarily closed -entry of sodium into cell is prevented

Identify and describe the 4 functional neuron segments, including the distribution of pumps and channels in each.

Receptive Segment: -Includes dendrites and cell body -chemically gated channels -More Na+ moving in than K+ moving out -NO significant voltagegated channels Initial Segment: -composed of axon hillock -contains voltage-gated Na+ channels and voltage-gated K+ channels with Na+ moving in and K+ moving out Conductive Segment: -consists of the length of the axon and telodendria -contains voltage-gated Na+ channels and voltage-gated K+ channels with Na+ moving in and K+ moving out Transmissive Segment: -includes synaptic knobs -contains voltage-gated Ca2+ channels and Ca2+ pumps

Describe the all or none principle

Refers to the fact that all stimuli that bring the membrane to threshhold generate identical action potentials.

Compare the absolute refractory period with the relative refractory period

Refractory- The time between the initiation of an action potential and the restoration of the normal resting membrane potential

Module 9.5: describe a major characteristic of excitable membranes and its importance in generating action potention

Repolarization- K+ released Depolarization- Na+ is released

Module 9.9: Describe the mechanism required responsible for tension production in a muscle fiber, and discuss the factors that determine the peak tension

Sarcomere length reduction: less tension Decrease in resting sarcomere length reduces tension Tension hits zero when thick filaments cannot shorten. Peak tension occurs when muscle is at optimal resting length

Identify the neuroglia of the PNS

Satellite cells and Schwann cells

Explain the functional organization of the nervous system

Sensory(afferent): receiving information from receptors that defect stimuli and transmitting this information to the CNS Motor(efferent): initiating and transporting motor output from the CNS to effectors

Explain the characteristics of skeletal muscle fibers,

Skeletal muscle fibers are enormous, and they're multinucleate.

Name the three types of muscle tissue, identify where they are found, and list their functions. (Module 9.1A)

Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle forms the heart and propels blood. Smooth muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels.

Module 9.2:Organization of skeletal muscle at the tissue level

Skeletal muscle- Complex organ containing Muscle fibers, Connective tissues that harness the forces of contraction, blood vessels that nourish muscle fibers, and nerves that control contractions. Epimysium: surrounds entire muscle Perimysium: fibrous layer that divides the skeletal muscle into a series of compartments. Muscle fascicle: bundle of muscle fibers. endomyosium:areolar tissue surrounding muscle fibers Myosatellite cells: stem cells that function in damage repair

Name the effectors of the ANS

Smooth muscle, cardiac muscle, glands, and adipose tissue

What effect would a chemical that blocks voltage-gated sodium ion channels in a neurons plasma membrane have on its membrane potential?

Sodium ions could not rush into the ell and its membrane potential will not change.

Explain how nerves are classified structurally and functionally

Structural: Cranial and Spinal Functional: Sensory, Motor, and Mixed

Define summation, and describe the 2 types of summation that can occur in the initial segment

Summation: Graded postsynaptic potentials (EPSPs and IPSPs) are added together in the initial segment Spatial summation: Occurs when multiple presynaptic neurons release neurotransmitter at various locations onto the receptive segment of the postsynaptic neuron, thus generating EPSPs, IPSPs, or both. Temporal summation:occurs when a single presynaptic neuron releases excitatory neurotransmitter to stimulate the postsynaptic neuron at the same location repeatedly in a very short period of time.

The endomysium __________.

Surrounds individual muscle fibers

Describe the mechanisms by which muscle fibers obtain the energy to power contractions.

Sustained muscle contraction uses a lot of ATP energy ATP and CP Reserves The storage molecule for excess ATP energy in resting muscle Using the enzyme creatine phosphokinase (CPK or CK) WhenCPisusedup,other mechanisms generate ATP

Compare temporal summation with spatial summation

Temporal- addition of a rapid succession of stimuli occuring at a single synapse. Spatial- the addition of stimultaneous stimuli applied at different locations

What does the ATP do

The ATP 'cocks' the myosin head allowing it to pivot

Compare the central and peripheral nervous system

The CNS consists of the brain and spinal cord. It integrates, processes, and coordinates sensory data and motor commands. The PNSincludes all nervous tissue outside the CNS.

What initiates a muscle contraction?

The action potential along motor neuron ends at the synaptic terminal and releases ACh into the synaptic cleft of the motor end plate

The number of pivoting cross bridges depends on

The amount of overlap of myosin and actin

A band

The area that has both actin and myosin fibers and includes the H band

I band

The area that has only actin fibers

Which is true regarding events that occur at neuromuscular junctions?

The binding of acetylcholine molecules to the receptors alters the membrane's permeability.

What determines the frequency of action potential generation?

The degree of sustained depolarization at the axon hillock determines the frequency of action potential generation

Describe the connective tissue layers associated with skeletal muscle tissue. (Module 9.2B)

The epimysium surrounds the entire muscle; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds individual muscle fibers.

identify the three connective tissue layers associated with skeletal muscle tissue.

The epimysium, perimysium, and endomysium

Describe the relationship between the number of fibers in a motor unit and the precision of body movements. (Module 9.10C)

The finer and more precise the movement, the fewer the number of muscle fibers in the motor unit.

The greater degree of sustained depolarization at the axon hillock, the ___ (higher or lower) the frequency of action potentials generated

The greater the degree of sustained depolarization at the axon hillock, the higher the frequency of generation of action potentials.

Explain the relationship between load and speed of muscle contraction. (Module 9.11A)

The greater the load on a muscle, the longer it takes for the muscle to shorten, and the less it shortens.

What happens when the cell runs out of ATP

The head won't reset which causes the fiber to stop contracting

Define information processing

The integration of stimuli by an individual cell

What is the sarcolemma

The membrane of a muscle cell (fiber). action potentials begin with ions crossing this membrane

Define resting potential

The membrane potential of an undisturbed cell

What would happen if there were no AChE in the synaptic cleft? (Module 9.6C)

The motor end plate would be continuously stimulated and continuous muscle contraction would occur.

Describe the neuromuscular junction. (Module 9.6A)

The neuromuscular junction is where the axon terminals of a motor neuron interact with the skeletal muscle fiber midway along the fiber's length.

Describe the neurilemma of a myelinating and nonmyelinating Schwann cell

The outer surface of the myelin sheath covering an internode of one axon.

H Band

The part of the A band that Has thick fibers (myosin) but no thin fibers actin

Zone of overlap

The part of the A band that has both myosin and actin fibers

What special terms are used to describe the plasma membrane and cytoplasm of a skeletal muscle fiber? (Module 9.2C)

The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm.

What is the relationship between myelin and the propagation speed of action potential?

The presence of myeline greatly increases the propagation speed of action potentials

Define action potential

The propagated changes the membrane potential of excitable cells

Explain why the propagation of action potentials along electrically excitable membranes occurs in only one direction. (Module 9.5D)

The refractory period prevents it from propagating back in the direction from which it began.

Which division of the PNS brings info to the CNS?

The sensory division of the PNS

Describe a synapse

The site where a neuron communicates with another cell. It involves a presynaptic cell and a postsynaptic cell.

Which occurs during an eccentric contraction?

The tension developed is less than the load, causing the muscle to lengthen while it is contracted.

Define membrane potential

The unequal charge distribution between the inner and outer surfaces of the plasma membrane.

Which of the following statements is not true about action potentials?

They can travel in two directions.

Module 9.4: Structural components of think & thick filaments

Thin filaments: F-actin: 2 rows of 300-400 G-actin Nebulin- large protein that extends along the F-actin strand in the cleft G-actin- Active bonding site Tropomyosin- prevent actin and myosin interaction. Troponin: 3 globular subunits

Define transverse tubules. (Module 9.3B)

Transverse tubules are tubular extensions of the sarcolemma that extend deep into the sarcoplasm contacting the terminal cisternae of the sarcoplasmic reticulum.

Integrate the concepts of voltage, current, and resistance with neuron structure and function.

Voltage- the measure of the amount of difference in electrical charge between two areas(plasma membrane) and represents potential energy Current- the movement of charged particles across the barrier that separates this charge difference(generated by diffusion of ions through their specific channels) Resistance- the opposition to the movement of charged particles(phospholipid bilayer of the plasma membrane)

Contrast the white matter and gray matter in the CNS

White matter​ of the CNS is dominated by myelinated axons. The gray matter includes areas containing neuron cell bodies, dendrites, and unmyelinated axons

What would happen to a muscle if the motor end plate failed to produce AChE?

Without the AChE, the motor plate would be continuously stimulated by ACh, locking the muscle in a state of contraction

F-actin

a twisted strand made of G-actin molecules

Function of cisternae

accumulate Ca via ion pumps outside the sarcomeres, then release the Ca into sarcomeres to begin muscle contraction

Triggering of the muscle action potential occurs after

acetylcholine binds to chemically gated channels in the motor end plate membrane.

which would be more likely to create an oxygen debt: swimming laps or lifting weights?

activities that require short periods of strenuous activity produce a greater oxygen debt, because they rely on anaerobic metabolism. weightlifting would be more likely to create an oxygen debt

Which type of metabolism (respiration) is used for resting muscle

aerobic

A resting muscle generates most of its ATP by

aerobic metabolism of fatty acids.

muscle striations

alternating bands of filaments

Decreased blood flow to a muscle could result in all of the following except

an increase in intracellular glycogen.

Which type of metabolism is used during peak muscle activity

anaerobic

When comparing slow fibers to fast fibers, slow fibers

appear dark red.

Describe Intermediate Fibers

are mid-sized,have low myoglobin,have more capillaries than fast fiber, are slower to fatigue

Describe slow twitch fibers

are slow to contract, slow to fatigue, have small diameter, more mitochondria, have high oxygen supply contain myoglobin (a red pigment that binds oxygen) distance runners.

Where is the motor end plate located

at the sarcolemma (cell membrane of a muscle cell)

How would severing the tendon attached to a muscle affect the muscle's ability to move a body part?

because tendons attach muscles to bones, severing the tendon would disconnect the muscle from the bone, and so the muscle could not move the bone

Troponin

bound to tropomyosin, has a calcium binding site which is empty until stimulation of the fiber. No contraction until calcium binds and the troponin-tropomyosin complex is moved out of the was of the binding site

How do muscles continuously synthesis ATP?

by utilizing creatine phosphate and metabolizing glycogen and fatty acids. Most cells generate ATP only through aerobic metabolism in the mitochondria and through glycolysis in the cytoplasm.

What are the byproducts of aerobic respiration

carbon dioxide and water

Name the structural components of a typical neuron

cell body, axon, and dendrites

terminal cisternae

chambers of SR which surround the fibrils adjacent to the t tubules

What are the four components of skeletal muscles

connective tissue, nerves, muscle fibers, blood vessels

Describe fast twitch fibers

contract quickly, large diameter, few mitochondria (usually produce anaerobic response) sprinters

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for

contraction.

Which of the following is not a recognized function of skeletal muscle?

controlled involuntarily

What is the function of the endomysium

covers each muscle fiber -- contains motor neurons and capillaries that feed individual fibers and also has myosatellite cells for regeneration

What is the function of the epimysium

covers entire muscles

What is the function of the perimysium

covers fascicles -- contains nerves and blood vessels for the fascicles

Tropomyosin

covers the active sites under resting conditions

thick filaments (A band)

dark--myosin

Epimysium

dense layer of collagen fibers around the entire muscle (part of the deep fascia)

During the ________ phase of action potential development, voltage-gated sodium channels are open.

depolarization

Na+ and K+ both use ________ to passively diffuse across the plasma membrane.

leak channels

Thin filaments (I band)

light--actin (thIn)

When acetylcholine binds to receptors at the motor end plate, the end plate membrane becomes

more permeable to sodium ions.

Receptors for acetylcholine are located on the

motor end plate

A single motor neuron together with all the muscle fibers it innervates is called a(n)

motor unit.

Neurons and ________ have electrically excitable membranes that propagate action potentials.

muscle cells

Name the protein that make up a thick filament. (Module 9.4B)

myosin and titin

Cross-bridges are portions of

myosin molecules.

Rigor mortis __________.

occurs as the sarcoplasmic reticulum deteriorates, releasing calcium ions

Describe synaptic fatigue

occurs in an axon terminal when neurotransmitters are released into the synaptic cleft at a faster rate than they can be reabsorbed or recycled

Triad

one T-tubule and the adjoining 2 cisternae

How much overlap produces the greatest amount of tension

optimal overlap, too much or too little is inefficient

muscle fascicles are surrounded by:

perimysium and contain muscle fibers

What does the head of the myosin molecule do

pivots to grab and pull actin

Of the following clinical conditions affecting skeletal muscle, which is caused by a virus?

polio

identify the six major functions of skeletal muscle

produce skeletal movement, maintain posture and body position, support soft tissue, guard body entrances and exits, maintain body temperature, and store nutrients

Titin

protein fibers that extend from the Z line to the thick fibers

Define refractory period, and explain the difference between the absolute refractory period and the relative refractory period associated with transmitting an action potential.

refractory period: brief time after an action potential has been initiated during which an axon is either incapable of generating another action potential OR a greater than normal amount of stimulation is required to generate another action potential. Absolute refractory period: time (about 1 millisecond) after an action potential onset when no amount of stimulus, no matter how strong, can initiate a second action potential. Relative refractory period: occurs immediately after the absolute refractory period

After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as

rigor mortis.

The type of muscle fiber that is most resistant to fatigue is the ________ fiber.

slow

Which type of muscle fiber predominates in the leg muscles of endurance athletes, such as long-distance runners? (Module 9.14C)`

slow fibers

What is a myoblast

small fiber cell with one nucleus

What happens when the ACh binds to receptors on the sarcolemma

sodium gates open allowing Na to rush in

sarcomeres

structural units of myofibrils (muscle fibers)

Oxygen debt

the amount of oxygen required to restore normal, pre-exertion conditions in muscle tissue

Membrane potential is

the electrical gradient of a cell.

Z Line

the ends of the sarcomere, it is also where the actin fibers join

What is glycolysis

the first two steps of respiration

M Line

the midline of the sarcomere, it is also where the myosin fibers join

What is the sliding filament theory

the myosin fibers remain stationary while the actin fibers are pulled toward the M line.

Describe the components of a chemical synapse

the site where a neuron communicates with another neuron or with a cell of a different type- are a presynaptic cell and a postsynatic cell whose plasma membranes are seperated by a narrow gap called the synaptic cleft.

Define a synapse

the specific location where a neuron is functionally connected to either another neuron or an effector.

Describe the neuromuscular junction

the synapse between a motor neuron and a skeletal muscle cell. the connections enables communication between the nervous system and a skeletal muscle fiber

where would you expect to find the greatest concentration of calcium ions in resting skeletal muscles?

the terminal cisternae of the sarcoplasmic reticulum

T- tubules

these are quasi neurons that carry the action potential deep throughout the muscle fiber to all the filaments

What do myosatellite cells do

they are a type of stem cell that fuses myoblasts into muscle fibers

what feature of cardiac muscle allows the heart to act as a functional syncytium?

they are joined by gap junctions, which allow ions and small molecules to flow directly between cells, as a result APs generated in one cell spread rapidly to adjacent cells, thus all the cells contract simultaneously in a unit

a sarcomere contains:

thick filaments, thin filaments, proteins that stabilize the position of the thick and thin filaments and proteins that regulate the interactions between thin and thick filaments.

At rest, active sites on the actin are blocked by

tropomyosin molecules.

When calcium ion binds to troponin,

tropomyosin moves into the groove between the helical actin strands.

sarcoplasmic reticulum (SR)

weblike structure surrounding a fiber, helps transmit action potential to myofibril and is attached to the T-tubules

When does a muscle contraction begin?

when stored calcium ions are released from the sarcoplasmic reticulum into the sarcoplasm through gated calcium channels

Which of the following best describes the term "Z line"?

where thin filaments are anchored

How do you get a sustained muscular contraction

with many repeated stimuli

Can a skeletal muscle contract without shortening?

yes, the muscle can shorten, elongate, or remain the same length, depending on the relationship between the load and the tension produced by actin-myosin interactions.