Muscle

Question 1

Skeletal muscle

Answer 1

controls voluntary movements innervated by the somatic nervous system connects one bone to another bone stores large amounts of glycogen to use to power muscle contractions and provide heat to the body

Question 2

tendon

Answer 2

Connective tissue that connects muscle to bone Can store elastic potential energy

Question 3

Functions of muscle

Answer 3

1. body movement 2. stabilization of body position 3. movement of substances through the body 4. generating heat to maintain body temperature

Question 4

ligament

Answer 4

connective tissue that connects bone to bone

Question 5

Smooth muscle and cardiac muscle

Answer 5

innervated by the autonomic nervous system control heart rate and blood pressure

Question 6

sarcomere

Answer 6

the smallest functional unit of the contractile apparatus in skeletal muscle composed of many strands of two kinds of protein filaments: 1. thick filaments - made of myosin; 2. thin filaments - made of actin

Question 7

thick filaments

Answer 7

One of two types of filaments that makes up a sarcomere Composed of several long myosin molecules wrapped around each other to form one thick filament Have myosin heads protruding along both ends of the thick filament

Question 8

thin filaments

Answer 8

One of two types of filaments that make up a sarcomere Composed of actin Proteins troponin and tropomyosin are attached to the actin thin filament

Question 9

troponin

Answer 9

A protein attached to the actin that aids in the mechanism of contraction. Binds calcium, causing a conformational change in troponin, which then pulls tropomyosin back and exposes the active site of the actin thin filament, allowing the myosin head to bind and form a cross bridge.

Question 10

tropomyosin

Answer 10

A protein attached to the actin that aids in the mechanism of contraction. Covers the active site of the actin thin filament. Moves out of the way when calcium binds to troponin and troponin moves tropomyosin.

Question 11

Z line

Answer 11

separates one sarcomere from the next and is where actin filaments attach

Question 12

I band

Answer 12

The part of a sarcomere that contains actin only (includes the Z line)

Question 13

H zone

Answer 13

The area containing myosin only

Question 14

A band

Answer 14

The area where myosin is present, including where it overlaps with actin Includes the H zone

Question 15

M line

Answer 15

The midline of the myosin fibers

Question 16

myofibril

Answer 16

sarcomeres positioned end to end form a myofibril, each of which is surrounded by the specialized endoplasmic reticulum of the muscle cell, the sarcoplasmic reticulum.

Question 17

sarcoplasmic reticulum

Answer 17

the endoplasmic reticulum of a muscle cell. The lumen is filled with Ca2+ ions

Question 18

multinucleate

Answer 18

each muscle cell contains many nuclei

Question 19

myocite/muscle fiber

Answer 19

several myofibrils wrapped together

Question 20

fasciculus

Answer 20

Many muscle fibers bound together form a fasciculus

Question 21

single muscle

Answer 21

Many fasciculi together make up a single muscle

Question 22

Overall anatomy of muscle

Answer 22

Sarcomeres line up end to end to form myofibrils, which are wrapped together by the sarcolemma to form a muscle cell. Many muscle cells bound together form a fasciculus and many fasciculi form a muscle

Question 23

Sliding Filament Theory

Answer 23

Actin and Myosin work together by sliding alongside each other to create the contractile force of skeletal muscle. Each myosin head crawls along the actin in a 5-stage cycle.

Question 24

Important properties of myosin head

Answer 24

1. Magnesium - ATP head 2. ATPase activity 3. A site for binding actin

Question 25

Sliding Filament theory

Answer 25

The idea that myosin and actin work together by sliding alongside each other to create the contractile force of skeletal muscle

Question 26

Cross Bridge

Answer 26

When the myosin head binds to the actin filament, we call this a cross bridge.

Question 27

motor unit

Answer 27

consists of a neuron and the fibers in the muscle that it innervates. one neuron can innervate 2-2000 fibers. Small muscles have small motor units and large muscles, requiring more force, have larger motor units. [a small motor unit would be one neuron innervating 2 fibers; a large motor unit would be one neuron innervating 2000 fibers.]

Question 28

Muscle fiber types

Answer 28

Type 1 and Type 2

Question 29

Type 1

Answer 29

Type 1 – slow twitch – slow oxidative fibers –Highly aerobic –Contain mitochondria and ample myoglobin, which gives them a red color and makes them slow to fatigue –Have a relatively slow contractile velocity (speed of contraction) and produce a low amount of force

Question 30

Type 2

Answer 30

Type 2 – fast twitch – fatigue quickly and are heavily glycolytic a. Type 2A – fast oxidative fibers –Also red, but they have a fast contractile velocity More resistant to fatigue than Type2B, but not as resistant as Type 1 b. Type 2B – fast glycolytic fibers –Low myoglobin content and thus appear white –Contract rapidly and can generate a lot of force, but fatigue quickly –Contain large amounts of glycogen

Question 31

Muscle cell changes

Answer 31

–Muscle cells do not undergo mitosis generally –Muscles grow by increased diameter of the muscle fibers, increased numbers of sarcomeres and mitochondria, and lengthened sarcomeres

Question 32

T tubules

Answer 32

have their origin on the cell surface and come down to branch into the cell. T-tubules carry the action potential deep inside the cell and interact with the sarcoplasmic reticulum to cause calcium release.

Question 33

sarcoplasmic reticulum

Answer 33

–the endoplasmic reticulum of the muscle cell –Contains calcium to control contraction

Question 34

nebulin

Answer 34

a structural protein in the sarcomere that helps align actin

Question 35

Titan

Answer 35

a structural protein in the sarcomere that provides elasticity and stabilizes myosin

Question 36

what happens to the bands in a sarcomere as muscle contraction occurs?

Answer 36

During muscle contraction, each sarcomere shortens as the thin filaments slide closer together between the thick filaments so that the Z lines are pulled closer together. The width of the A bands does not change as a muscle fiber shortens, but the I bands and H zones become shorter.

Question 37

rigor state

Answer 37

When myosin and actin are bound but before ATP comes in to bind myosin and make it release. Rigor mortis results from no more ATP being produced in the body (b/c someone is dead) and therefore myosin does not release actin