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Spring of 2012 > Muscle Tissue (Exam 2) > Flashcards

Muscle Tissue (Exam 2) Flashcards

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0
Q

Excitable tissue

A

Only contracts in response to electrical activity on the surface of the muscle cell membrane

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1
Q

General characteristics

A

Excitable tissue
Contracts
Relaxes
Makes up about 40% of the average persons body mass

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2
Q

General functions

A

Body movement (skeletal)
Maintenance of posture (skeletal)
Production of heat as a by product of activity (all)
Constriction of organs and blood vessels (smooth)
Production of heart beat (cardiac)

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3
Q

Gross anatomy

A

Connective tissue

Neural innervation

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4
Q

Connective tissue

A

Epimysium
Perimysium
Endomysium

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5
Q

Epimysium

A

Dense connective tissue layer around the whole muscle

Also called fascia

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6
Q

Perimysium

A

CT covering around the bundles of muscle fibers called fasciles

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7
Q

Endomysium

A

Reticular CT that surrounds each of the fibers in the fascile

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8
Q

Motor neuron

A

Specialized nerve cells
Somas are in the spinal cord
Axons extend to muscle fibers
Function: electrically stimulate the muscles to contract

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9
Q

Neuromuscular junction

A

The contact between the axon terminal and the muscle

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10
Q

Motor unit

A

One motor neuron + all the muscle fibers it innervates

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11
Q

Sarcolemma

A

Plasma membrane

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12
Q

Sarcoplasm

A

Intracellular fluid

Contains glycosomes and myoglobin

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13
Q

Glycosomes

A

Store glycogen for energy

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14
Q

Myoglobin

A

Red pigmented oxygen storing protien

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15
Q

Microscopic general characteristics

A

Each fiber is a long cylindrical cell with multiple oval nuclei
Each muscle fiber is made of many myofibrils

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16
Q

Myofibrils

A

Thread like structures that extend from one end of the muscle to the other
Made of myofilaments

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17
Q

Myofilaments

A

Action (thin filament)

Myosin (thick filament)

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18
Q

Actin

A

Each myofilament is made of:
Tropomyosin
Troponin
F-actin

19
Q

F-actin

A

Fibrous actin
Coiled to form a double helix
Made of 200 G-actin

20
Q

G-actin

A

Small globular protiens

Has an active site to which myosin binds during contraction

21
Q

Tropomyosin

A

Stabilizing protien that winds along a groove in the F-actin strand

22
Q

Troponin

A

3 polypeptide complex

TnI bonds to G-actin
TnT binds to tropomyosin, anchoring it to the F-actin strand
TnC binds to Ca+2

23
Q

Myosin

A

Each filament has:
a rod like tail consisting of two entwined polypeptide chains
Two heads that have three components each

Binding site for actin
Binding site for ATP
Hinge region

24
Binding site for actin
Has ATPase activity | Splits an ATP to yield ADP, Pi, and energy
25
Hinge region
Junction of the head and the tail | Allows the head to bend and straighten during contraction
26
Z-disk/line
Protien attachment site for the actin
27
Sarcomer
Structural units of actin and myosin Functional unit of a muscle Extends from one Z-disk to another Striations can be seen under a microscope due to alternating light and dark bands A bands I bands H zone M line
28
A bands
Dark bands consisting of actin and myosin
29
I bands
Light bands consisting of actin only
30
H zone
Band in the middle of the A band | Myosin only
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M line
One in the middle of the H zone that holds the myosin in place
32
Sarcoplasmic reticulum (SR)
Surrounds each myofibril | Upon electrical stimulation it releases Ca+2 from the lateral sacs
33
Transverse tubule (T-Tubule)
Invagination of the muscle cell sarcolemma Runs between lateral spaces to form a triad (1 t tubule+2 lateral sacs= a triad) Functions to quickly transmit AP through out the muscle cell The AP signals the release of Ca+2 from the lateral sacs
34
Functions of ATP
Contraction | Relaxation
35
Contraction
Powers the ratcheting movement of the myosin head After each ratcheting movement a new ATP molecule binds to the myosin head so it can detach, then bind again to the next G-actin molecule
36
Relaxation
Powers the pump that removes Ca+2 from the sarcomere
37
Muscle metabolism
Continuous muscle contraction requires continuous ATP production Accomplished via 3 pathways: Direct phosphorylation Anaerobic respiration/glycolysis Aerobic respiration/oxidative phosphorylation
38
Direct phosphorylation of ADP by creatine phosphate (CP)
``` CP is an extremely high energy molecule that is stored in muscle 1st source of energy Reaction: Creatine phosphate + ADP= creatine + ATP Enzyme: creatine kinase Yield: 1 ATP per creatine phosphate About 15 seconds of activity ```
39
Anaerobic respiration/glycolysis
Does not require O2 Involves catabolism of glucose that has been obtained from the blood stream or from the breakdown of glycogen stores in the muscles (within glycosomes) Reaction: the glucose is broken down into ATP and pyruvic acid Yield: 2 ATP per 1 glucose About 30-60 seconds of activity
40
Aerobic respiration/oxidative phosphorylation
Requires O2 Pyruvic acid from glycolysis is transferred to the Kreb's cycle Within mitochondria high energy bonds are broken and ATP is released Yield: 34 ATP per 1 glucose Hours at activity + the 2 from glycolysis
41
Skeletal muscle fiber types
Slow oxidative fibers Fast glycolytic fibers Fast oxidative fibers Most muscles are a mixture of fiber types The predominant type can change based on need/use
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Slow oxidative fibers
Myosin ATPases work slow, therefore speed of contraction is slow Uses oxidative phosphorylation for ATP production Red in color due to high myoglobin stores Relatively fatigue resistant and have high endurance Uses: long distance running and posture
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Fast glycolytic fibers
Myosin ATPases work fast therefore speed of contraction is fast Uses glycolysis to generate ATP White in color because there is no need for oxygen so no need for myoglobin Very susceptible to fatigue because of limited glycogen stores Uses: short term intense movements like lifting a large load
44
Fast oxidative fibers
Intermediate between slow oxidative and fast glycolytic Myosin ATPases work fast therefore speed of contraction is fast Uses oxidative phosphorylation and glycolysis for ATP production Has both myoglobin and glycogen stores Pink in color Moderately fatigue resistant Uses: walking

Spring of 2012 (56 decks)

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