Quiz 1 Flashcards by brock rose

What is the order of muscle structure from smallest to largest

MyoFilaments (actin/myosin)
Sarcomeres
Myofibrils
Muscle cells (muscle fibers)
Fascicles
Whole Muscle

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What are the layers of the extra cellular matrix

epimysium (wraps whole muscle)
Perimysium (wraps up fascicles)
Endomysium (wraps up muscle cells)
Sarcolemma (wraps up Myofibrils)

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What is the Sarcolemma

The cell wall of a muscle fiber

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What are the two parts of the sarcolemma

basement membrane (outside)

2. plasmalemma (inside)

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Where do you find satellite cells

between the two layers of the sarcolemma

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What is a Myofibril

a bunch of sarcomeres in series

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What is the smallest functional unit of muscle

the sarcomere

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What makes a muscle look striated

the sarcomeres

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What are myofilaments

myosin/actin

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What are the purposes of the Muscle Cytoskeleton

Structural integrity
Force transmission
Signal transduction

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What it Titin

The largest protein found in the sarcomere

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What is Titin associated with

Myosin

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What is the function of Titin

it holds the myosin molecule in place so that it can work with actin

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What is nebulin

The protein associated with actin that holds it in place, and supports it so that it can interact with myosin

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What comes first nebulin or actin

nebulin, the length of it determines how long the actin molecule will be

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What is the purpose of the extracellular muscle

helps strengthen it

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What is the function of satellite cells

they are involved in muscular regeneration and they can become myonuclei

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What is the Z disk

the scaffolding that actin holds to. It also forms an important cytoskeleton for the muscle. holds each myofibril lined up with the others

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What is the m line

the myosin scaffolding

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what is the A band

anywhere where myosin is present

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what is the I band

where there is no myosin present

what is the H zone

the place where there is only myosin

What is a unique feature of Titin

the half without myosin surrounding it is extensable

What is a Costamere

A conglomeration of proteins that connects the sarcolemma to the myofibril right below it. (subsarcolemma myofibril)
It hooks onto the Z disk

What is Dystrophin

The most important protein in the costamere. If it is removed the whole thing doesn't work

What is muscular Dystrophy

when Dystrophin molecule is absent or mutated

How common is muscular dystrophy

1 in 3500 births

What happens when you have muscular dystrophy

- muscle breaks down - adipose tissue replaces it - muscle cells become circular - Death at early 20's B/c the heart and respiratory muscle don't work

When does muscular dystrophy show itsefl

when children start to bear loads

What is Desmin

A protein found at the Z lines that holds each Z disk together maintaining the important uniform arrangement of myofibrils (holds each myofibril together)

What are the roles of desmin

- holds myofibrils together - holds myofibrils correctly alligned - transmits force from the sarcomere to the sarcolemma and to the muscle as a whole

what are the contractile proteins of muscle

- Myosin and Actin

What type of Myosin is found in skeletal muscle

Myosin II

What is the function of myosin

motor protein, force generator

Where is myosin seen

the A band

What is the MHC (myosin heavy chain)

it is one myosin molecule (head and tail region)

What regions of myosin get together to form the thick filament

Tail regions

What makes up the head of myosin

1. Actin binding site | 2. ATPase site

What determines contraction velocity

The type of MHC and ATPase on the myosin

What geometric shape does the way that actin surrounds the Myosin molecule resemble

a hexagon

What is Actin

- The thin filament | - contractile protein

What are the two types of actin

G and F

What is G actin

globular actin (individual Actin proteins)

What is F actin

filamentous actin (a G actin polymer)

What shape does the F actin take

double helix

What does G actin have on it

Active sites with a high affinity for Myosin

What are the two regulatory proteins

Tropomyosin and troponin

What does Tropomyosin do

runs in the groove of the actin helix and blocks the myosin binding sites of actin

What does Troponin do

CIT 1. Calcium - binds to 2. Inhibits - mysoin binding sites of actin 3. Tropomyosin - bound to When it binds calcium it changes conformation, moves off the myosin binding site, and pulls tropomyosin off of the myosin binding site too.

How many troponin are there per actin molecule

1 troponin per 7 actin molecules

What were the steps in discovering the sliding filament theory

1. viewing banding patterns 2. interdigitation of myofilaments 3. Altering dimensions of the A bands, I band

What are the steps of the crossbridge cycle

1. Calcium binds to troponin 2. troponin and tropomyosin move off the myosin binding sites of actin 3. Myosin head binds to actin 4. Powerstroke happens 5. ATP binds to myosin head causing it to release from Actin 6. ATPase breaks ATP down returning the myosin head back to the cocked stage 7. if calcium is still present it starts over