Nakamura Human Anatomy Ch 10,11

Question 1

What does muscle contraction depend on?

Answer 1

Two types of myofilamints
-actin (thin)
-myosin (thick)
These two proteins generate contractile force

Question 2

Plasma membrane/ cell membrane in muscle tissue

Answer 2

Sarcolemma

Question 3

Sarco

Answer 3

Muscle

Question 4

What is the cytoplasm in the muscle tissue called?

Answer 4

Sarcoplasm

Question 5

Each muscle is…

Answer 5

An organ

• consists mostly of muscle tissue
• skeletal muscle also contains
  
  • connective tissue (sheaths)
  • blood vessels (nutrients)
  • nerves (w/o these muscle won’t move)

Question 6

Basic features of a skeletal muscle

Answer 6

• connective tissue sheaths
• fascicles
• nerves and blood vessels
• muscle attachments

Question 7

What are muscle cells in skeletal and smooth muscle called?

Answer 7

Muscle fiber

Question 8

Nerves and blood vessels in skeletal muscle

Answer 8

• each skeletal muscle supplied by
  
  • one nerve
  • one artery (carry oxygenated blood away from heart)
  • one or more veins (return deoxygenated blood to heart)
• nerves and blood vessels branch repeatedly
• smallest nerve branches (dendrites in single neuron axon) serve individual muscle fibers
  - neuromuscular junction: signals the muscle to contract (these are connections between neuron nerve branches and muscle fibers (cells))

Question 9

Muscle attachments on a skeletal muscle

Answer 9

-most skeletal a muscles run from one bone to another
-one bone will move and the other remains fixed
-origin: less movable attachment
-insertion: more movable attachment
Ex. Biceps: on humerus is the origin, the insertion on radius

Question 10

Connective tissue and fascicles on a skeletal muscle

Answer 10

• connective tissue sheaths bind a skeletal muscle and its fibers together
• epimysium, perimysium, endomysium
• are continuous with tendons(attach muscle to bone)

Question 11

Epimysium

Answer 11

Dense irregular connective tissue surrounding entire muscle

Outer

Question 12

Perimysium

Answer 12

Surrounds each fascicle (group of muscle fibers)

Around

Question 13

Endomysium

Answer 13

A fine sheath of connective tissue wrapping each muscle fiber (cell)
Inside

Question 14

Skeletal muscle fiber

Answer 14

Fibers are long and cylindrical
•Are huge cells – diameter is 10-100µm
•Length – several centimeters to dozens of centimeters
–Each cell formed by fusion of embryonic (stem) cells
–Cells are multinucleate (multiple nuclei in one cell)
–Nuclei are peripherally located (not in the middle)

Question 15

Myofibrils

Answer 15

Striations result from internal structure of myofibrils (contain actin and myosin)
●long rods within cytoplasm
–Make up 80% of the cytoplasm (sarcoplasm)
–Like a specialized contractile organelle found in muscle tissue
–A long row of repeating segments called sarcomeres (function unit)

Question 16

Sarcomere

Answer 16

The basic unit of contraction of skeletal muscle (also called FUNCTION UNIT)
–Z disc (Z line): boundaries of each sarcomere
–Thin (actin) filaments: extend from Z disc toward the center of the sarcomere
–Thick (myosin) filaments: located in the center of the sarcomere
•Overlap inner ends of the thin filaments
•Contain ATPase enzymes (without ATP no contraction)

Question 17

Sarcomere structure

Answer 17

A bands: full length of the thick filament (myosin).
–Includes inner end of thin filaments
-located in middle of sarcomere
●H zone: center part of A band where no thin filaments occur
●M line: in center of H zone
–Contains tiny rods that hold thick filaments together
●I band: region with only thin filaments
–Lies within two adjacent sarcomeres

Question 18

Sliding filament theory

Answer 18

-Myosin heads attach to actin in the thin filaments
–Then pivot to pull thin filaments inward toward the center of the sarcomere
-myosin head: ATP located here, called power stroke

Question 19

Titin

Answer 19

-a spring-like molecule in sarcomeres
–Resists overstretching
–Holds thick filaments in place (why myosin doesn’t move)
–Unfolds when muscle is stretched (only one that moves in contraction)

Question 20

Sarcoplasmic reticulum

Answer 20

-a specialized smooth ER (ACR)
-Interconnecting tubules surround each myofibril
•Some tubules form cross-channels called terminal cisternae
•Cisternae occur in pairs on either side of a t tubule (storage for calcium. No calcium, no contraction)
–Sarcoplasmic reticulum Contains calcium ions, which are released when muscle is stimulated to contract
–Calcium ions diffuse through cytoplasm
•Trigger the sliding filament mechanism

Question 21

Muscle contraction

Answer 21

-Ultimately controlled by nerve-generated impulse
–Impulse travels along the sarcolemma of the muscle cell
•Impulses further conducted by t tubules

Question 22

T tubule

Answer 22

a deep invagination (insertion of a structure within itself or another) of the sarcolemma
-conducts impulse

Question 23

Muscle fibers divided into three main classes based on:

Answer 23

-Strength, speed, and endurance of contraction
•Most muscles contain all three fiber types
–Red slow-twitch (Slow oxidative fibers; type I)
–White fast-twitch (Fast glycolytic fibers; type IIx or typellb)
–Intermediate fast-twitch (Fast oxidative fibers; type IIa)

Question 24

Red slow-twitch fibers

Answer 24

-Red color due to abundant myoglobin (protein to carry oxygen)
–Obtain energy(ATP) from aerobic (depends on oxygen) metabolic reactions
–Contain a large number of mitochondria (make ATP)
–Richly supplied with capillaries
–Contract slowly and resistant to fatigue
(Also called slow oxidative fibers; type 1)

Question 25

White fast-twitch fibers

Answer 25

-Contain little myoglobin and few mitochondria –About twice the diameter of slow-twitch fibers –Contain more myofilaments(contain actin and myosin) and generate more power –Depend on anaerobic pathways –Contract rapidly and tire quickly (Type llb, type llx, fast glycolytic fibers)

Question 26

Intermediate fast-twitch fibers

Answer 26

-Have an intermediate diameter –Contract quickly like white fibers –Are oxygen-dependent (aerobic) –Have high myoglobin content and rich supply of capillaries –Somewhat fatigue-resistant (duration) –More powerful than red slow-twitch fibers (Type lla, fast oxidative fibers)

Question 27

Muscles are classified into several functional groups

Answer 27

- prime mover (agonist) - antagonist - synergistic

Question 28

Prime mover

Answer 28

Agonist | -has major responsibility for a certain movement

Question 29

Antagonist

Answer 29

Opposes or reverses a movement

Question 30

Synergist

Answer 30

Helps the prime mover -by adding extra force –By reducing undesirable movements –Fixator: a type of synergist that holds a bone firmly in place (that usually adjusts our posture and opposes gravity) Ex. Anterior and posterior muscles, depending on what body position we are in, maintain our posture

Question 31

Naming the skeletal muscle

Answer 31

- direction of fascicles and muscle fibers - location of attachments - number of origins - action - location - shape - relative size

Question 32

Direction of fascicles and muscle fibers

Answer 32

–Name tells direction in which fibers run (striations) | –Example: rectus abdominis and transversus abdominis

Question 33

Location of attachments

Answer 33

– name reveals point of origin and insertion | –Example: brachioradialis

Question 34

Number of origins

Answer 34

– two, three, or four origins | –Indicated by the words biceps, triceps, and quadriceps

Question 35

Action

Answer 35

-the action is part of the muscle’s name –Indicates type of muscle movement •Flexor (to bend), extensor, adductor, or abductor (to move away from the median plane)

Question 36

Location

Answer 36

Ex: brachialis is located on the arm

Question 37

Shape

Answer 37

Ex. The deltoid is triangular

Question 38

Relative size

Answer 38

- Maximus, minimus, and longus indicate size | - ex: gluteus Maximus and gluteus minimus

Question 39

Terminal cistern of Sarcoplasmic reticulum

Answer 39

Group of Sarcoplasmic reticulum

Question 40

Combination of muscle fibers (muscle cells) makes..

Answer 40

Diff types of muscle tissue, which makes diff muscle organs