Muscle Tissue (Exam 2) Flashcards Preview

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

Flashcards in Muscle Tissue (Exam 2) Deck (45)
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0
Q

Excitable tissue

A

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

1
Q

General characteristics

A

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

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)

3
Q

Gross anatomy

A

Connective tissue

Neural innervation

4
Q

Connective tissue

A

Epimysium
Perimysium
Endomysium

5
Q

Epimysium

A

Dense connective tissue layer around the whole muscle

Also called fascia

6
Q

Perimysium

A

CT covering around the bundles of muscle fibers called fasciles

7
Q

Endomysium

A

Reticular CT that surrounds each of the fibers in the fascile

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

9
Q

Neuromuscular junction

A

The contact between the axon terminal and the muscle

10
Q

Motor unit

A

One motor neuron + all the muscle fibers it innervates

11
Q

Sarcolemma

A

Plasma membrane

12
Q

Sarcoplasm

A

Intracellular fluid

Contains glycosomes and myoglobin

13
Q

Glycosomes

A

Store glycogen for energy

14
Q

Myoglobin

A

Red pigmented oxygen storing protien

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

16
Q

Myofibrils

A

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

17
Q

Myofilaments

A

Action (thin filament)

Myosin (thick filament)

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
Q

Binding site for actin

A

Has ATPase activity

Splits an ATP to yield ADP, Pi, and energy

25
Q

Hinge region

A

Junction of the head and the tail

Allows the head to bend and straighten during contraction

26
Q

Z-disk/line

A

Protien attachment site for the actin

27
Q

Sarcomer

A

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
Q

A bands

A

Dark bands consisting of actin and myosin

29
Q

I bands

A

Light bands consisting of actin only

30
Q

H zone

A

Band in the middle of the A band

Myosin only

31
Q

M line

A

One in the middle of the H zone that holds the myosin in place

32
Q

Sarcoplasmic reticulum (SR)

A

Surrounds each myofibril

Upon electrical stimulation it releases Ca+2 from the lateral sacs

33
Q

Transverse tubule (T-Tubule)

A

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
Q

Functions of ATP

A

Contraction

Relaxation

35
Q

Contraction

A

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
Q

Relaxation

A

Powers the pump that removes Ca+2 from the sarcomere

37
Q

Muscle metabolism

A

Continuous muscle contraction requires continuous ATP production
Accomplished via 3 pathways:
Direct phosphorylation
Anaerobic respiration/glycolysis
Aerobic respiration/oxidative phosphorylation

38
Q

Direct phosphorylation of ADP by creatine phosphate (CP)

A
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
Q

Anaerobic respiration/glycolysis

A

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
Q

Aerobic respiration/oxidative phosphorylation

A

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
Q

Skeletal muscle fiber types

A

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

42
Q

Slow oxidative fibers

A

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

43
Q

Fast glycolytic fibers

A

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
Q

Fast oxidative fibers

A

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

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