Vert Phys Exam #2

Somatic Nervous System: Skeletal muscle contraction is

neurogenic

___ movement requires that muscle activity be __ ___

Purposeful, high coordinated

Purposeful movement is

useful for survival

What brain levels are involved in purposeful movement

higher and lower

Voluntary movement is at what brain level?

Higher brain level

Cerebellum- balance and nose example is what kind of movement

voluntary

Intent matches outcome- what brain level

lower brain level

Proprioception

sense of static position and movement of limbs, body, and head

How stretched a muscle is and angle of joints are examples of ?

proprioception

Somatic neurons are __ from CNS to target muscle- __ cell long

continuous, one

— and — will interact with a single skeletal muscle fiber

brain, each terminus

— —- will have lots of skeletal muscles

Whole muscle

What does a whole muscle that has lots of skeletal muscles do?

It will control contraction of whole muscle by controlling concentration of each individual one

motor unit

functions as a unit; when it fires an AP all muscle fibers contract simultaneously as a single functional entity

How many blue and red motor units are there?

4 blue, 2 red

neuromuscular junction

axon of efferent motor neurons connecting spinal cord to muscle

Physiology of the Neuromuscular Junction

synapse between somatic motor neuron and somatic skeletal muscle cell

Spinal reflexes are — motor responses to a particular - - integrated at - - level

Involuntary, sensory stimulus, spinal cord

Monosynaptic reflex arc

primary stimulus with one synapse, disposed directly with motor neuron

Polysynaptic reflex arc

more than one synapse; receptor cell, interneuron, afferent sensory neuron, CNS, efferent motor neuron, effector cell

Which type of synaptic reflex arc is most common

Polysynaptic reflex arc

What is an example of a monosynaptic reflex arc

the stretch reflex

Process of the stretch reflex:

trigger stimulus, rapid sudden stretch, same muscle will contract

If - - reflex is normal and the whole pathway is intact, then something will occur

patellar tendon; stretch will depolarize the muscle spindles and alpha motor neuron, and contraction occurs because of pulling on the quadriceps by hitting it, because it moves back into the space behind the knee

Two characteristics of the stretch reflex

unable to prevent them and they are the fastest

What is an example of the postsynaptic reflex arc

Withdrawal (flexor) reflex

A Withdrawal (flexor) reflex is in response to

pain/ painful stimulus

How does a Withdrawal (flexor) reflex work?

flexion of join in the limb, joint flexes or bends to remove from painful stimulus, preventing tissue damage

What are the three ways the painful stimulus depolarizes

contraction of the bicep, contraction of the tricep, and synapsing with the higher brain sensory

Contraction of the bicep

excitatory interneurons stimulate alpha motor neurons leading to bicep (flexor) causing it to contract and pull arm away while inhibiting tricep (extensor) to prevent it from bending arm

Contraction of the tricep

The tricep (extensor) is inhibited

Synapsing with the higher brain sensory

signal travels in the ascending pathway to the brain; taking in information for memory, prevents further tissue damage, and can be voluntarily overcome

What are the properties of muscle tissue

Electrical excitability, contractibility, extensibility, and elasticity

Electrical excitability

able to untilize

Contractibility

they can contract and produce force, trigger movement

Extensibility

they can be stretched past resting equilibrium length (resting state) without being damaged

Elasticity

ability to recover from some deformation

Striated muscle

due to molecular complex organization of cell, similarities between the two

What two muscles are striated

Skeletal and Cardiac

Skeletal muscle is -

Voluntary: muscle tissue construction is controlled by the somatic nervous system

Cardiac muscle is

involuntary; influenced by autonomic nervous system and pacemaker cells in SA node

Unstriated muscle

involuntary tissues that lack striped bonds found in skeletal muscle

What muscle is unstriated

Smooth

Smooth muscle

involuntary

Whole skeletal muscles are bundles of elongated - - - -packaged together by layers of - -

multinucleate muscle cells (myofibers); connective tissues

Periosteum covering the bone

membrane that covers outer surface

Tendon

strong connection between muscle and bones because all connective tissues (extracellular material)

Fascia

continuous, web-like band of fibrous connective tissues that wraps, supports, and separates every muscle, organ, nerve, and bone

Skeletal Muscle

striated muscle tissue attached to bones by tendons that consciously control to move your body

Epimysium

outermost layer of dense connective tissues that surrounds entire skeletal muscle

Perimysium

binds to fascicle

Fascicle

single bundle

Endomysium

surrounded by myofiber

Muscle fiber (myofiber)

innermost layer (myo-muscle)

Myofiber

skeletal muscle cell that has multiple nuclei

Myofibril

rod-like contractile structures that consist of longitudinally (end to end) repeated functional units called sarcomeres

Myofilament

contractile protein (thick and thin filaments); causing light or dark for A and I bands

Sarcomere

functional units of striated muscle that shorten during contraction; found in skeletal and cardiac muscle

functional units

smallest unit of something that contains all the characteristics of a whole

Thick filament

myosin; A band, M line, and H zone

A band

entire length of thick filament

M line

segment of protein in the middle of sarcomere; anchors center of thick filament

H zone

portion of thick filament that doesn’t overlap thin filament

Thin filament

actin; I band

I band

portion that doesn’t overlap with thick filament

What is important for contraction and where must thin filaments move to

changes in overlap of thick and thin filament; towards M line

Dark bands

A bands L

light bands

I bands

What kind of bands to sarcomere have?

a whole dark band (A band) and half of neighboring light band (I band) on either side

The dark line is a _

Z-disk- localized group of proteins that will bind to sarcomere

Glycogen granules

glucose store in glycogen by vertebrate; muscle is using energy to create force for movement

What is the sliding filament mechanism of skeletal muscle contraction  

As thin filament goes towards M line the width of band/ zones get shorter

In the sliding filament mechanism of skeletal muscle contraction, what changes

H zone, I band, and sarcomere get shorter while A band stay the same

What happens when the sliding filament mechanism of skeletal muscle contraction is relaxed or contracted

level of overlap is changing

The primary protein complex of thick filament is - and what is its function

myosin; motor protein with coupled chemical energy for movement; head groups have ATPase activity (hydrolyze ATP), thermodynamically favorable, coupled to movement- bending of head region that causes movement

• How the thin filaments are pulled together towards the center

What does each myosin have

a tail, two neck (allows sliding), and two head regions

Two types of thin filaments

actin and troponin-tropomyosin complex

Function of actin

two strands of actin coil to form thin filament; actin has a myosin binding site (cross-bridge binding site)

Cross-bridge binding site

head of myosin and interaction with actin via weak interaction/ affinity

Troponin-Tropomyosin complex

both always attached, function together to impose inhibition or allow it to be removed; inhibition dictated by regulatory proteins

Cross-bridge cycle:

coupling of ATP hydrolysis to the generation of mechanical force

What is the starting state of cross-bridge cycle

state from when muscle is in relaxed-primed state

• head groups primed, neck regions extended; high affinity for cross-brige binding site, ADP and Phosphate

Cross-bridge cycle: step 1

1. Cross-bridge formation: primed myosin head groups bind to available cross-bridge binding sites

   1. High probability because head groups have high affinity for cross-bridge binding sites

   2. Full cycle occurs

Cross-bridge cycle: step 2

Power Stroke: bending of neck regions initiated by release of inorganic phosphate (ADP) from myosin head

Cross-bridge cycle: step 3

1. Cross-bridge dissociation: binding of ATP decrease affinity of the myosin head group for the cross-bridge binding site

   1. change in conformation leads to decrease affinity of myosin head group for the cross-bridge binding site

Cross-bridge cycle: step 4

1. Priming of myosin head group: ATP hydrolysis causes the neck region to extend, returning the myosin head to its energized conformation with high affinity for the cross-bridge binding site (ADP and inorganic phosphate still associated)

   1. ATP hydrolysis is responsible for priming

Triggering of skeletal muscle AP is from

release of neurotransmitter Ach which binds to nicotinic Ach receptor, causing Na2+ channels to open allowing for the influx of Na2+ which will depolarize the end plate potential (graded potential) to trigger a skeletal muscle AP

Graded potentials - neighboring - - channels (consisted with those in neurons)

depolarize; voltage gated

skeletal muscle AP: excitation-contraction coupling

propagated AP in muscle plasma membrane- travels into muscle through T-tubules to trigger calcium release from sacroplasmic reticulum and initiate contraction

Contraction is

triggered

Excitation causes

AP in muscle fiber (sarcolemma) and subsequent release of Ca2+ ions in the sarcoplasmic reticulum

APs propagate along - - into the depths of each muscle fiber, so changes in - - can influence things deeper inside

transverse tubules, membrane potential

transverse tubules (T-tubules)

Extension of the plasma membrane, the lumen is interstitial fluid, so it allows APs to propagate, so graded potentials can influence deep structures for contraction

Electrical signal of APs are

localized

The bulk solution is _ neutral

electron

The change is membrane potential is

localized

Lateral sacs are also known as

terminal cisterns

Lateral sacs (terminal cisterns)

enlarged, flat chambers of sarcoplasmic reticulum

Segments of sarcoplasmic reticulum have

specialized enlarge portion on either side of T-tubule