BIO201 Exam 3 - ASU Topal Latest updated questions and answers + rationales - Grand Canyon University

Slow-twitch, slow oxidative (SO), red or type I fibers

Fast-twitch, fast glycolytic (FG), white, or type II fibers

Fast-twitch, intermediate, or type IIA fibers

What are the physiological classes of muscle fibers?

Well adapted for ENDURANCE, resist fatigue by ATP PRODUCTION

Important for muscles to MAINTAIN POSTURE

Abundant mitochondria, capillaries, myoglobin: deep RED color

Contain a form of myosin with SLOW ATPase, and a SR that RELEASES CALCIUM SLOWLY

Relatively THIN FIBERS

Grouped in SMALL MOTOR UNITS controlled by small, EASILY EXCITED MOTOR NEURONS allowing for precise movements

Slow-twitch, slow oxidative (SO), red or type I fibers

A disease that destroys motor neurons in brainstem and anterior horn in spinal cord

Caused by poliovirus

Spread by fecal contamination of water

inactive polio vaccine (IPV)

What is poliomyelitis?

Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease)

Destruction of motor neurons and muscular atrophy. Astrocytes fail to reabsorb the neurotransmitter glutamate from tissue fluid (accumulate to toxic levels)

Sclerosis - scarring of lateral regions of the spinal cord

Sensory - they can feel but they cannot respond to it

What is ALS?

Myoglobin

How is oxygen provided to type I fibers?

Fibers are well adapted for QUICK RESPONSES

Important for QUICK and POWERFUL MUSCLES

Contain a form of myosin with FAST ATPase and a large SR that RELEASES CALCIUM QUICKLY

Utilize glycolysis and anaerobic fermentation for energy

- Abundant glycogen and creatine phosphate

- Lack of myoglobin gives them pale (WHITE) appearance

Fibers are THICK and STRONG

Grouped in LARGE MOTOR UNITS controlled by larger, LESS EXCITABLE NEURONS allowing for powerful movements

Fast-twitch, fast glycolytic (FG), white, or type II fibers

Fast-twitch but fatigue resistant

Known in other animals but rare in humans

Fast-twitch, intermediate, or type IIA fibers

1. An action potential reaches the end of the motor neuron

2. Calcium ion protein channels in the motor neuron are stimulated to open, and calcium ions enter the motor neuron

3. The influx of calcium ions causes vesicles containing the neurotransmitter acetylcholine to fuse with the membrane of the motor neuron

4. Acetylcholine diffuses across the synaptic cleft and binds to receptor sites on the membrane of the muscle fiber

5. The sodium ion channels open, and sodium ions diffuse into the muscle fiber

6. The influx of sodium ions depolarizes the membrane of the muscle fiber

Steps of NMJ in muscle contraction

Thick filament

What main protein filament makes up elastic filament?

Myosin protein

What protein makes up the thick filament?

Isometric contraction

What does this picture describe?

Isotonic contraction

What does this picture describe?

Isometric and isotonic

What are the two types of contraction?

Concentric and eccentric

What are the subcategory contractions that pertain to isotonic contraction?

muscle shortens as it maintains tension

What is isotonic concentric contraction?

muscle lengthens as it maintains tension

What is isotonic eccentric contraction?

Muscle develops tension but does not shorten, no movement

What is isometric contraction?

Muscles changes in length with no change in tension

What is isotonic contraction?

A band

H band

M line

I band

Z discs

Sarcomere

What makes up striations in muscle fibers?

A segment from Z disc to Z disc - smallest functional contractile unit of muscle fiber

Muscle cells shorten because individual sarcomeres shorten

What is a sarcomere?

It is the smooth ER in muscle fiber/cell - forms a network around each myofibril: calcium reservoir

What is the function of SR (sarcoplasmic reticulum) in the muscle cell?

Red pigment, stores oxygen needed for muscle activity - part of sarcoplasm

What is the function of myoglobin in the muscle cell?

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side

What is the function of transverse (T) tubules in the muscle cell?

Sarcolemma

Sarcoplasm

- myofibrils

- glycogen

- myoglobin

- mitochondria,

- sarcoplasmic reticulum (SR))

Multiple Nuclei (myoblasts, satellite cells)

SR (listed under sarcoplasm, has subcategories)

- terminal cisternae

- transverse (T) tubules

- Triad (T tubule and two terminal cisterns)

What are the parts of the muscle cell?

cytoplasm of muscle fiber

What is sarcoplasm?

long protein bundles that occupy the main portion of the sarcoplasm

What are myofibrils?

energy storage, stored in abundance to provide energy with heightened exercise

What is glycogen?

red pigment, stores oxygen needed for muscle activity

What is myoglobin?

dilated end-sacs of SR which cross the muscle fiber from one side to the other

What are terminal cisternae?

a T tubule and two terminal cisterns

What is a triad in the muscle cell?

Neuromuscular junction - when target cell is a muscle fiber

What is NMJ?

Calcium stimulates (electricity) exocytosis of acetylcholine from synaptic vesicles - so without calcium, there is no acetylcholine to produce/allow excitation

What is the importance of calcium in terms of excitation?

Calcium diffusing (electricity) in the cytoplasm between myosin and actin filaments of the muscle fibrils causes the filaments to slide into each other, triggering the contraction of the entire muscle fiber

What is the importance of calcium in terms of contraction?

tropomyosin and troponin

What are the regulatory proteins in muscle fiber?

thick filament myosin and thin filament actin proteins

What are the contractile proteins in muscle fiber?

ATP supplies the energy needed for the muscle fiber to:

- Move and detach cross bridges

- Pump calcium back into SR

- Pump Na+ out of and K+ back into cell after excitation-contraction coupling

Why is ATP so important for all muscle contractions and relaxations?

Aerobic respiration - produces 95% of ATP during this type of exercise

Where does ATP come from during rest, and light-to-moderate exercise?

Anaerobic pathway: glycolysis and lactic acid formation

Where does ATP come from during short intense exercise?

ATP is produced much faster in the anaerobic pathway so the energy can get to the muscles faster due to energy demand based off intensity - aerobic is much slower but yields much more amounts of ATP contributing to a longer and more steady flow of energy

Why does ATP come from anaerobic pathway instead of aerobic respiration during high intense SHORT workouts?

Excess post-exercise oxygen consumption - oxygen debt - heavy breathing after strenuous exercise to replace depleted oxygen reserves

What is EPOC?

Forms part of coccygeal ligament to anchor the spinal cord to coccyx (the other ligament to help with the support of the spinal cord is the denticulate ligament)

What is the function of filum terminale?

fibrous structures that help to anchor the spinal cord in place

What is the denticulate ligament?

They can contract due to a built-in pacemaker that sets off a wave of electrical excitation, it is autorhythmic, able to contract rhythmically and independently

Why don't cardiac muscles need nerve stimulation?

They lack nerve supply, are scanty, dependent, and receive help from ECF (extra-cellular fluid) for muscle contraction

Why don't smooth muscles need nerve stimulation?

a charge difference across the plasma membrane

What is resting membrane potential (RMP)?

-70 mV for neuron and -90 mV for muscle fiber

(negative meaning that there are more negatively charged particles on the inside of the membrane than on the outside)

What is the charge of a resting unstimulated neuron compared to a skeletal muscle fiber?

(Sodium-potassium pump) Na+/K+ pumps out 3 Na+ for every 2 K+ it brings in. Works continuously to compensate for Na+ and K+ leakage, and requires great deal of ATP

How is resting membrane potential maintained?

Na+ concentrated outside of cell (ECF)

K+ concentrated inside cell (ICF)

Where is the Na+ and K+ located in regards to resting membrane potential?

responsible for the regulation of excitation-contraction coupling

What is the function of the triad?

Muscle relaxation requires ATP, and ATP production is no longer produced after death, so the muscles harden and stiffen 3-4 hours after death. Muscles contract due to release of Ca+2 but can't relax

What is the cause of rigor mortis?

Satellite cells

What cell plays a role in repairing skeletal muscles?

used at the neuromuscular junctions, triggering the firing of motor neurons and affecting voluntary movements (ACTIVATE) - stimulate skeletal muscle but slow heart rate

What is the function of acetylcholine (ACh)?

to terminate neuronal transmission and signaling between synapses to prevent ACh dispersal and activation of nearby receptors (SHUT DOWN)

What is the function of acetylcholinesterase (AChE)?

Meninges (protective membranes of CNS)

Metastasis from non neuronal tumors in there organs

Often glial cells that are mitotically active throughout life -

NEURONS CAN NOT CAUSE TUMOR BECAUSE THEY CAN NOT DO MYTOSIS

Where do brain tumors arise from?

Brain and spinal cord (integrative and control centers)

Which organs are included in the central nervous system (CNS)?

visceral nervous system

What is another name for the autonomic nervous system (ANS)?

Support and protect the neurons

Bind neurons together and form framework for nervous tissue

In fetus, guide migrating neurons to their destination

If mature neuron is not in synaptic contact with another neuron it is covered by glial cells

- prevents neurons from touching each other

- gives precision to conduction pathways

What are the functions of the neuroglia or, glial cell?

It is an amino acid neurotransmitter

gamma (ɣ)-aminobutyric acid

It is the most inhibitory transmitter in the brain. It blocks, or inhibits, certain brain signals and decreases activity in your nervous system

GABA hyperpolarizes cell

What is GABA?

case in which membrane voltage shifts to a less negative value. Voltage across the membrane drifts toward zero and becomes briefly positive, Na+ channels open

What is depolarization?

A short-range change in voltage

Localizes in the Soma area

Graded: vary in magnitude (voltage) with stimulus strength

Decremental: get weaker the farther they spread from the point of simulation

Reversible: when stimulation stops, K+ diffusion out of cell returns the cell to its normal resting potential

Either excitatory or inhibitory: some neurotransmitters (glycine) make the membrane potential more negative-hyperpolarize it-so it becomes less sensitive and less likely to produce an action potential

What is local potential?

more dramatic change produced by voltage-regulated ion gates in the plasma membrane. All-or-none law

Nondecremental

Irreversible

Soma: (50-75 gates per μm^2); cannot generate an action potential

Trigger zone: (350 to 500 gates per μm^2); where action potential is generated

- if excitatory local potential spreads all the way to the trigger zone and is still strong enough when it arrives, it can open these gates and generate an action potential

What is action potential?

Loss of positive potassium ions turns the membrane negative again - K+ channels open

what is repolarization?

a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization

what is hyperpolarization?

Repolarization is caused by the closing of sodium ion channels and the opening of potassium ion channels.

Hyperpolarization occurs due to an EXCESS of open potassium channels and potassium efflux from the cell

What is the difference between hyperpolarization and repolarization?

No stimulus of any strength will trigger AP

As long as Na+ gates are open

From action potential to RMP

What is absolute refractory period?

only especially strong stimulus will trigger new AP

- K+ gates are still open and any effect of incoming Na+ is opposed by the outgoing K+

What is relative refractory period?

the period of resistance to stimulation - that has two phases (relative and absolute)

What is the refractory period?

relative refractory period

Which refractory period can fire a signal and the signal is strong?

Oligodendrocytes

What glial cells form the myelin sheath in the CNS (central nervous system)?

Schwann cells

What glial cells form the myelin sheath in the PNS (peripheral nervous system)?

An insulated layer around the nerve fiber that consists of plasma membrane of glial cells

20% protein

80% lipid

What is myelin sheath made out of?

It starts at the bottom of the brain stem and goes down to the lower back (C1 to L3/L4)

Where does the spinal cord start and end?

Vertebral fractures usually

What type of fractures cause spinal cord injury/trauma?

Efferent fibers that carry signals AWAY from CNS to muscles and glands

What is a motor sensory neuron (nerve)?

Afferent fibers that carry signals from sensory receptors TO the CNS

What are sensory neurons (nerves)?

(Association) Neurons that are in-between, and connect spinal motor and sensory neurons

carry out integrative function "make decisions"

90% of all neurons

Located in CNS

What are interneurons?

Hypertrophy - when the existing cells enlarge

How does the muscle get bigger?

Speed at which a nerve signal travels along a nerve fiber depends on two factors:

- Diameter of fiber (larger fibers = more rapid signals)

- Presence or absence of myelin (myelin = speeds signal conduction)

What is the conduction speed of nerve fiber?

Larger fibers have more surface area and conduct signals more rapidly

How do large fibers affect conduction speed of nerve fiber?

It further speeds signal conduction

How does myelin affect conduction speed of nerve fibers?

faster; faster

In regards to conduction speed of nerve fibers:

Large fibers = ________________; Myelinated fibers = __________________

PNS (peripheral nervous system)

Nerve fiber regeneration only happens in what nervous system?

its soma is intact and at least some neurilemma remains

In what condition can a nerve in the PNS regenerate?

Na+ channels close leaving most of the Na+ ions inside the cell, then K+ channels open fully open and K+ leaves from inside to outside of the cell

During repolarization, what is happening with Na and K ions?

Na+ channels open and Na+ ions are entering the nerve (are inside) and K+ channels are beginning to open and about to release K+ ions from inside to outside of the cell

During depolarization, what is happening with Na and K ions?

some K+ channels remain open (pushing K+ outside of cell) and Na+ channels reset

During hyperpolarization, what is happening with Na and K ions?

occurs when a single synapse receives many EPSPs (excitatory postsynaptic potentials) from many presynaptic cells

What is spatial summation?

Acetylcholine (ACh)

which neurotransmitter excites skeletal muscle and inhibits cardiac muscle

glutamate

what is the most common excitatory neurotransmitter?

GABA (gamma-aminobutyric acid)

what is the most common inhibitory neurotransmitter?

When a muscle is stretched, it "fights back" and contracts. Helps maintain equilibrium and posture

Ex: head starts to tip forward as you fall asleep, muscles contract to raise the head

Ex: Knee jerk from tendon tap (spinal component)

What is the stretch (myotatic) reflex?

1. Nerve Signal arrives at synaptic knob and opens voltage gated calcium channels, which open and release ACh.

2. Two (2) ACh molecules bind to each receptor protein and open the channel.

3. With channel open, Na+ enters the cell, increasing the RMP to +75mV.

4. K+ then exits the cell, changing the voltage back down to -90mV. (End Plate Potential)

5. Voltage change in end plate region opens nearby voltage gated channels, producing action potential spread over muscle surface.

Nerve action potentials lead to muscle action potentials

What are the steps of excitation in NMJ?

Excitation

What creates end plate potential?

Basal lamina (thin layer of collagen and glycoprotein) separates Schwann cell and entire muscle from surrounding tissue, creates acetylcholinesterase (AChE - which shuts down ACh) and the muscle fiber develops tension and may shorten

How does contraction work in the NMJ?

After contraction, the acetylcholinesterase breaks down the acetylcholine returning to its resting length

How does relaxation work in the NMJ?

movement, stability, control of body openings and passages, heat production, glycemic control

What are the functions of the muscles?

Muscle cell and myofiber

What are other names for muscle fiber?

skeletal, cardiac, smooth

3 types of muscular tissue

Cardiac muscles

Striated and involuntary muscles

Skeletal muscles

Striated and voluntary muscles