2NEURO Skeletal Contraction and Dystrophies

Question 1

What is purpose of our muscles?

Answer 1

40% of body, move bones. 3. Only shortens. 4. Antagonist contract/shorten to stretch

Question 2

How are msk packed?

Answer 2

In to out- myofibrils cells contractile proteins bundles into fibers. Fibers bundle into fascicles

Question 3

The membrane of a muscle cell is called?

Answer 3

Sarcolemma. Sacroplasmic reticulum stores calcium

Question 4

What are layers of muscle?

Answer 4

Fascia- skeletal muscle-perimysium-epimysim-fasicle-enodomysium-myofibrily

Question 5

What are the two long F polymers strands coiled around each other that are attached to z-disk w/in sarcomere?

Answer 5

ACTIN- Thin filament

Question 6

This structure is multiple protein wrapped around actin?What is ontop of this structure? What does it cover

Answer 6

Tropmyosin-cover active site ADP. Troponin is ontop of tropomyosin

Question 7

This structure has two helical proteins composed 6 polypetide chains as a tail with two head groups to as attachment sites?

Answer 7

MYOSIN-THICK

Question 8

How is a fiber innervated?

Answer 8

Contraction begins with a nerve stimulation, 1 nerve does not stimulate all fibers. parallel stack, not like cardiac. Contracts different fiber diff times

Question 9

Individual nerve fiber and all the muscles that are innervated?

Answer 9

motor unit- LARGE groups have fewer motor units, less fine tuning. SMALL group-hand, have more motor units smaller

Question 10

This space is where the neuron sits in the synaptic gutter in the sarclema which is folded w/ ACH receptor?

Answer 10

Neuromuscular junction

Question 11

What ion is used to release NT into the synaptic gutter?

Answer 11

Ca

Question 12

What is release in the NMJ and binds to ligand channel gated channel on the motor end plate (aka postsynaptic).

Answer 12

2 ACH create + charge, opens a Na, for influx thus moving potential to Na reversal potential for an AP

Question 13

This AP caused what to happen in the sarcoplasma reticulum?

Answer 13

Release calcium storage

Question 14

What is made up of troponin and where are its attachment sites?

Answer 14

3 protein units- Ti- ACTIN, TT-tropomyosin, TC-calcium

Question 15

At rest where is the tropomyosin/troponin proteins?

Answer 15

Covering Gprotein ADP active site on actin

Question 16

What causes myosin head to attach to actin?

Answer 16

AP release Ca from SR. Ca binds to TC. Changes structure pulls tropomyosin off binding site

Question 17

What pulls the Z-disk together?

Answer 17

ATP helps Bending of the myosin heads attached on actin. Hydrolysis forms ADP+P

Question 18

Why is max force 110% of sarcomere length?

Answer 18

Normal resting length is max tension developed. Shortening- tension limits force b/c z-disk block by myosin ends. No cross bridges at myosin center. Lengthen- actin cant bind to myosin

Question 19

What is work?

Answer 19

Load x Distance move. Greater load, greater velocity

Question 20

What is the meaning of life?

Answer 20

Phosphorylation. Creatine from kidney, made in liver. Creatine phosphate stored in muscle. Fast but short lived

Question 21

What is ideal energy source but long to develop, and last longer bc produce 6xmor ATP?

Answer 21

Oxidative phosphorylation from food. Glycolysis=INC ATP

Question 22

What are types of tension development?

Answer 22

Isometric-Tension=load no change in tension. 2. Isotonic- Tension >Load 3. Lengthening= Tension

Question 23

WHat fiber fatigues faster, larger, strong, Large SR, fast ion release, INC enzymes, blood supply reduced, fewer mitochondria?

Answer 23

FAST twitch

Question 24

What fiber less fatigue, more mitochondria, more blood supply, large myoglobin, depends on sugars and oxidative phosphorylation, generate more tension?

Answer 24

Slow twitch

Question 25

What motor units are more excitable?

Answer 25

Spatial summation- multiple units. Smaller unit contract 1st, but as signal grows large kick in. Smooth movement d/2 alternating various units

Question 26

What is state of sustained contraction over time?

Answer 26

Tetanus- temporal summation. Every moment

Question 27

What occurs during period of rest within sarcoplasmic retiuc that influence strength of contraction?

Answer 27

Stepwise rest periods show inc in Ca with each rest

Question 28

What contribute to muscle tone at rest?

Answer 28

Slow level of release of Ach from low baseline rate of nerve impulses. Provides bulk via trophic effect. IE Cerbral palsy-tonic contracture protective, UMN

Question 29

What occurs with loss of glycogen storage resulting in loss of strength/tension/contraction?

Answer 29

Fatigue- transmission of nerve also reduced with prolonged stimulation. Less ACH, Less CA, less strength IE. do PE neuro once

Question 30

Muscle apply tension at insertion on bone, this creates what type of system?

Answer 30

Lever system- force related to distance from fulcrum and length of lever arm. If LONG lever arm, close load to fulcrum= less force generation, easy

Question 31

What occurs with muscle hypertrophy?

Answer 31

fibers larger, more enzymes, new sarcomeres with size of stretch fiber

Question 32

What does muscle atrophy take place?

Answer 32

Denervation Starts immediately BUT cannot see til late.

Question 33

What occurs with denervation?

Answer 33

Fibers destroyed replaced with fibrous scar or fat. Neighbors motor units can sprout, but loss dextrixity

Question 34

What is characteristic of mixed muscle atrophy, hypertrophy, fiber replaced with scar and fat material, progressive in weakness as MC SX?

Answer 34

Dystrophies >30. 1. Mostly boys. 2Onset 3-5y. 3.Walk on tip toes 4. clumsy. Runs backward. Fall often. 5. Walks up from seated position. 6. Lordosis

Question 35

This disorder requires dystrophin- msk structure, but is inheritable absent?

Answer 35

Duchenne MD Onset 3-5yo. Most cant walk by age 12.

Question 36

This disorder is less severe form of dys dystrophin

Answer 36

Becker MD

Question 37

This MD slowly progressive disorder of face, arms, shoulder beginning in teen?

Answer 37

Fascioscapulohumeral

Question 38

MC adult form characterized by cardiac abnormalities and cataracts, swan neck (from inability to support the weight of the head), drooping eyelids

Answer 38

Myotonic

Question 39

What is most life threatening of MD?

Answer 39

Heart and breathing muscles get weak- Child usually dies before age 20 from heart failure or pneumonia.