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Anatomy > Muscular System > Flashcards

Muscular System Flashcards

0
Q

Contractility

A

shorten forcibly

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1
Q

Functions of muscular system

A 
Body movement
Maintenance of posture
Respiration
Production of body heat
Communication (speaking, writing, etc)
Constriction of organs & vessels
Heartbeat
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2
Q

Excitability

A

to receive & respond to stimuli

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3
Q

Extensibility

A

Can be stretched beyond its normal resting length & is still able to contract

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4
Q

Elasticity

A

to recoil to its original resting length after it’s been stretched

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5
Q

Skeletal muscle

A 
bones
multinucleated 
striated 
voluntary
involuntary (reflexes)
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6
Q

Smooth muscle

A

walls of hollow organs, blood vessels, eyes, glands, skin
single nucleus
nonstriated
involuntary

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7
Q

Cardiac muscle

A

branching fibers
single nucleus
striated
involuntary

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8
Q

Fascia

A

connective tissue sheets; outermost layer

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9
Q

Epimysium

A

dense collagen;

surrounds entire muscle

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10
Q

Fascicle

A

bundle of muscle fibers

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11
Q

Perimysium

A

surrounds fascicles; fibrous connective tissue

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12
Q

Endomysium

A

surrounds each muscle fiber;

fine sheath of connective tissue composed of reticular fibers

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13
Q

Myofibril

A

bundles of protein filaments within muscle cells; extend along length of muscle fiber (long)

myofilament- individual protein filaments: actin & myosin

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14
Q

Connective tissue functions

associated with muscles

A 
surround & protect muscle tissue
binds & holds muscles together
free movement of muscles
supports nerves & blood vessels
fills spaces between muscles
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15
Q

Sarcolemma

A

muscle cell plasma membrane

-> T tubules- indentations of sarcolemma; allows sarcolemma to extend to interior of muscle fiber

16
Q

Sarcoplasm

A

cytoplasm of muscle cell, fills sarcolemma;
consists of organelles OTHER than myofibrils:
-sarcoplasmic reticulum
-mitochondria
-glycogen granules

17
Q

Sarcoplasmic reticulum

A

endoplasmic reticulum;

stores & pumps Ca+ ions

18
Q

Actin (thin) myofilament

A 
strands of pearls
Fibrous (F actin) = strand
Globular (G actin) = pearls
  -> active site where myosin binds
troponin molecules are attached along actin, have Ca+ binding sites
19
Q

Myosin binding site is covered on G actin by:

A

tropomyosin when Ca+ is absent;
when present, site is uncovered for myosin to bind

MUST HAVE Ca+ FOR MUSCLE CONTRACTION & MYOSIN TO BIND

20
Q

Myosin (thick) myofilament

A

golf clubs
head- deep cleft, binds to active site on G actin (forming cross-bridge)
hinge- enables movement of head
rod- attach to each other; oriented so heads are at end of myosin myofilament

21
Q

Actin moves along

A

myosin

think of pulling a rope

22
Q

Sarcomere

unit of actin & myosin filaments

A

basic functional unit of striated muscle fibers

arrangement of actin & myosin = banded appearance

23
Q

Z disk

A

separates sarcomeres;
attachment site for actin
holds actin filaments in place
(blue zig zag line)

Z disks move toward each other during contraction

24
Q

A band

A

extends entire length of myosin;
contains H zone (AH)

does not narrow/change in sarcomere shortening (contraction)

25
Q

I band

A

connects end of one actin to beginning of other;
Z disk in middle;
contains 2 different sarcomeres;
extends to ends of myosin

narrows in contraction

26
Q

H zone

A

center of A band (sarcomere)
ONLY myosin

narrows & disappears in contraction (actin meets & overlaps)

27
Q

M line

A

middle of H zone;
holds myosin filaments in place
–> Titin

28
Q

What gives striated appearance under the microscope?

A

alternating A & I bands

29
Q

Myofilaments (actin & myosin) do not change _______ during muscle contraction

A

length;

they just “slide” over each other

30
Q

Contraction begins with:

A

head of myosin bound to actin.

Ca+ must be present

31
Q

Fully contracted muscle

A

H zone disappears

I band narrows

32
Q

Nervous system stimulates muscles through:

A

action potential (nerve impulses)

action potential -> inside of membrane becomes +

all or none principal -> going to happen or not -> must break threshold or muscle will not respond

33
Q

Ligand-gated ion channels

A

gates open in response to a ligand binding to a receptor

binding of a ligand allows ions to flow;
absence of ligand = gates closed

majority of ligands are NEUROTRANSMITTERS

34
Q

Voltage-gated ion channels

A

open & close in response to changes in voltage

35
Q

Axons of motor neurons enter muscles & send out branches

each branch =

A

neuromuscular junction (synapse)

an axon branch joins a muscle fiber

Anatomy (6 decks)

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