Chapter 43: Muscles, Bones, and Body Movements

Question 1

Which types of muscle are under voluntary control?

Answer 1

skeletal

Question 2

Which types of muscle are under involuntary control?

Answer 2

smooth and cardiac

Question 3

What connects bone to bone?

Answer 3

ligaments

Question 4

What connects muscle to bone?

Answer 4

tendons

Question 5

Which nervous system controls the skeletal muscle?

Answer 5

somatic nervous system

Question 6

Are skeletal muscles multinucleated?

Answer 6

yes

Question 7

What is a fasicle?

Answer 7

bundle of muscle fibers

Question 8

What are myofibrils? composition?

Answer 8

make up muscle fibers

made of thin and thick filaments

Question 9

What gives skeletal muscle a striated appearance?

Answer 9

alternating pattern of thin and thick filaments

Question 10

What are A bands?

Answer 10

Dark bands at both ends of stacked thick filaments where thin filaments overlap

Where ACTION takes place

Question 11

What is the H zone?

Answer 11

Lighter middle region of an A band, which contains only thick filaments

Question 12

What is the M line?

Answer 12

A disc of proteins in the center of the H zone, which holds the stack of thick filaments together

MIDDLE of the sarcomere

Question 13

What are I bands?

Answer 13

Light bands consisting of the parts of the thin filaments not in the A band

connects 2 sarcomeres

Question 14

What is the Z line?

Answer 14

A thin disc in the center of each I band to which the thin filaments are anchored

end, edge, boundary

Question 15

What is a sarcomere?

Answer 15

the basic unit of contraction in a myofibril

Question 16

What are thick filaments?

Answer 16

are parallel bundles of myosin molecules, each consisting of two subunits that form a head connected to a long double-helix tail – the head bends toward the adjacent thin filament to form a crossbridge

heads away from middle and towards the Z-line

Question 17

What are thin filaments?

Answer 17

contain two linear chains of actin molecules twisted into a double helix

tropomyosin and troponin are found here

Question 18

What happened to the sarcomere when a muscle is fully contracted?

Answer 18

-Z lines get closer together, doesn’t change shape just
moves
-actin and myosin overlap
-actin doesn’t change shape or move

Question 19

What does interdigitated mean?

Answer 19

(of two or more things) interlock like the fingers of two clasped hands.

Question 20

What are the steps in forming a cross-bridge/muscle contraction?

Answer 20

1) myosin head binds to ATP, detaches from actin
2) Myosin head catalyzes (breaks down) ATP forming ADP which cocks the myosin head back
3) Myosin head hinds to actin forming a cross-bridge
4) ADP and Pi are released which created a power stroke that causes thin filament to slide which shorten the sarcomere

Question 21

What is rigor mortis?

Answer 21

Can tell time of death by presence of ATP, For a while after death ATP is still produced which allows for cross-bridge formation still.

Within a few hours after death, Ca2+ diffuses into the cytoplasm of muscle cells and initiates the crossbridge cycle, producing rigor mortis

Question 22

What is the sarcoplasmic reticulum?

Answer 22

complex system of vesicles modified from smooth ER that encircle the sacromeres

Segments of sarcoplasmic reticulum wrap around each A and I band, separated from T tubules by small gaps

Question 23

What are T tubules?

Answer 23

At the junction of an A band and I band, the plasma membrane folds to form a T (transverse) tubule

on top of Z line, hollow tube that plunges down into the tissue

Question 24

What neurotransmitter is responsible for neural muscular control? what does this cause?

Answer 24

acetylcholine, causes the release o f Na+ ions that depolarize the membrane which then release Ca2+ ions from voltage gated channels

Question 25

What role does Ca2+ play in skeletal muscle contraction control?

Answer 25

In low Ca2+ levels, tropomyosin inhibits cross-bridge formation In high Ca2+ levels, Ca2+ binds to troponin, Tropomyosin is displaced, and formation of actin-myosin cross-bridges

Question 26

What is the difference between troponin and tropomyosin?

Answer 26

tropomyosin is the rope and troponin is the globular proteins that Ca2+ binds to

Question 27

What is botulinum?

Answer 27

Botulinum toxin blocks acetylcholine release in neuromuscular junctions – body muscles, including the diaphragm, become paralyzed and the victim dies of respiratory failure

Question 28

What is curare?

Answer 28

Curare blocks acetylcholine from binding to its receptors in muscle fibers – body muscles, including the diaphragm, become paralyzed and the victim dies of respiratory failure

Question 29

What will a single action potential arriving at a neuromuscular junction causes a single, weak contraction produce?

Answer 29

muscle twitch

Question 30

What is a twitch summation?

Answer 30

If a muscle fiber is restimulated before it has relaxed completely, the second twitch is added to the first, producing twitch summation

Question 31

What is tetanus?

Answer 31

If action potentials arrive so rapidly (about 25 msec apart) that the fiber can’t relax at all between stimuli, twitch summation produces a peak level of continuous contraction (tetanus)

Question 32

What are slow muscle fibers? where in the body would they be found in?

Answer 32

-contract slowly for longer periods of times. breakdown ATP slowly. -has a lot of mitochondria that makes ATP by oxidative phosphorylation. -high concentrations of myoglobin = tissue is redder found in postural muscles

Question 33

What is myoglobin? found more in?

Answer 33

enhances oxygen supply | found more in slow muscle fibers and fast aerobic muscle fibers

Question 34

What are the 2 types of fast muscle fibers? where in the body would they be found in?

Answer 34

aerobic and anaerobic found in finger muscles

Question 35

What is similar between aerobic and anaerobic fast muscle fibers?

Answer 35

both contract quickly and paler than slow muscle fibers both more fatigue quicker than slow muscle fibers

Question 36

What is different between aerobic and anaerobic fast muscle fibers?

Answer 36

aerobic has more mitochondria = ATP, and high concentration of myoglobin. Uses oxidative phosphorylation, and an intermediate capacity for making ATP by anaerobic glycolysis Anaerobic muscle fibers has high concentrations of glycogen, relatively few mitochondria, and a more limited blood supply than fast aerobic fibers. uses GLYCOLYSIS and has short bursts of rapids contractions

Question 37

Which fast muscle fiber is more susceptible to fatigue?

Answer 37

anaerobic

Question 38

Which muscle fiber would runners have more of?

Answer 38

slow twitch fibers

Question 39

What does working out do? in muscle fibers?

Answer 39

increases muscle mass via feedback particular types of exercise can convert some fast muscle fibers between aerobic and anaerobic types

Question 40

Can you create fine motor control?

Answer 40

nope, can't build more motor units can only get better via coordination

Question 41

What is a motor unit?

Answer 41

Muscle fibers are organized into motor units, each controlled by branches of the axon of a single efferent neuron will be the same type of muscle fiber

Question 42

What happens to the motor until when it contracts?

Answer 42

When a motor unit contracts, its force is distributed throughout the entire muscle because the fibers are dispersed throughout the muscle, not concentrated in one segment

Question 43

What is recuritment?

Answer 43

you can use a different amount of muscle units depending on the task---strength

Question 44

How do motor units differ in different areas of the body?

Answer 44

Muscles that can be precisely and delicately controlled, such as finger movements, have many motor units in a small area Muscles that produce larger body movements, such as leg movements, have fewer motor units in the same volume of muscle, but thousands of muscle fibers in each unit

Question 45

What is fatigue?

Answer 45

muscle failure, multivariable problem

Question 46

What is creatine?

Answer 46

released in muscle tissue breakdown and can be used to look at kidney function

Question 47

What are the 3 types of skeletons?

Answer 47

hydrostatic skeletons, exoskeletons, and endoskeletons

Question 48

How do hydrostatic skeletons work?

Answer 48

consists of a body compartment or compartments filled with water or body fluids – which are incompressible liquids If muscles in one part of the compartment are contracted and another part is relaxed, pressurized fluid moves to the relaxed part of the compartment, distending it uses pressure and density of H2) to build structure

Question 49

How do hydrostatic skeletons work in earthworms?

Answer 49

- Circular muscles reduce diameter and increase length - Longitudinal muscles shorten length and increase diameter - "feet"/keta provide friction

Question 50

Where do hydrostatic skeletons occur?

Answer 50

Hydrostatic skeletons are the primary support systems of cnidarians, flatworms, roundworms, and annelids Many arthropods have hydrostatic skeletal elements (e.g., larvae of flying insects and legs of spiders) Some structures of echinoderms are supported by hydrostatic skeletons (e.g., tube feet of sea stars and sea urchins) In vertebrates, the erectile tissue of the penis is a fluid-filled hydrostatic skeletal structure

Question 51

What is an exoskeleton?

Answer 51

is a rigid external body covering that supports and protects internal tissues – the force of muscle contraction is applied against the exoskeleton

Question 52

What are the two types of exoskeletons? What organisms are they found in?

Answer 52

Many mollusks, such as clams and oysters, have an exoskeleton consisting of a hard [calcium carbonate] shell secreted by glands in the mantle Arthropods, such as insects, spiders, and crustaceans, have a [chitinous cuticle] secreted by underlying tissue – joints are moved by muscles that extend across the inside surfaces found in smaller organisms

Question 53

What is an endoskeleton?

Answer 53

consists of internal body structures, such as bones, that support and protect soft tissues – the force of muscle contraction is applied against the bones

Question 54

What type of skeletons do echinoderms have?

Answer 54

Echinoderms have an endoskeleton consisting of ossicles formed from calcium carbonate crystals

Question 55

What type of skeletons do sea urchins and sand dollars have for thier shells?

Answer 55

endoskeletons

Question 56

What is the difference between the axial and appendicular skeleton?

Answer 56

axial= skull, spine, ribcage appendicular= appendages and pelvis

Question 57

What are they 2 types of bone? where are they found?

Answer 57

spongy and dense compact dense compact bone, which generally forms the outer surfaces, and more open spongy bone, found in interior regions

Question 58

Is the bone vascular in humans? birds?

Answer 58

yes in humans, allows for repair nope in birds

Question 59

What is osteoporosis?

Answer 59

loss of bone matirx

Question 60

How can you tell if you have broken a bone?

Answer 60

very quickly there will be a dark colored bruise where blood from the broken bone is collecting

Question 61

What is red marrow and where is it found?

Answer 61

The interior of some flat bones, such as hip bones and ribs, are filled with red marrow, a tissue that is the primary source of new red blood cells in mammals and birds

Question 62

What is yellow marrow and where is it found?

Answer 62

The shaft of long bones such as the femur is opened by a large central canal filled with adipose tissue called yellow marrow, which is a source of some white blood cells

Question 63

What hormones are involved in calcium levels in the bone? function?

Answer 63

calcitonin decreases blood calcium levels by stimulating osteoblasts to build bone Parathyroid hormone decreases blood calcium levels by stimulating calcium reabsorbtion

Question 64

What are the 3 types of joints?

Answer 64

fibrous, cartilaginous, and synovial

Question 65

What are synovial joints?

Answer 65

consist of the cartilage covered ends of two bones, enclosed by a capsule of connective tissue filled with synovial fluid, and held together by ligaments freely movable

Question 66

What are cartilaginous joints?

Answer 66

the ends of bones are covered with cartilage, but have no fluid􏰁filled capsule surrounding them – the bones are connected by fibrous connective tissue semi movable

Question 67

Are fibrous joints movable? what type of bone?

Answer 67

nope, they are flat and compact bone

Question 68

What is a hinge joint?

Answer 68

The elbow and the knee are hinge joints This type of joint can move only in one direction to open or close the angle between the bones flanking it.

Question 69

What is a ball-and-socket joint?

Answer 69

Shoulder and the hip joints exemplify ball-and-socket joints This type of joint can rotate about its axis, providing the greatest range of motion of any joint in the body

Question 70

What is a fulcrum? example?

Answer 70

pivot point that bones move around The elbow joint has the fulcrum at one end, the load at the opposite end, and force applied between the ends

Question 71

What is an agonist muscle?

Answer 71

A muscle that causes movement in the joint when it contracts

Question 72

What is an extensor muscle?

Answer 72

extend joint

Question 73

What is a flexor muscle?

Answer 73

opposite of extensor muscle

Question 74

What are the antagonistic muscle pairs?

Answer 74

extensor and flexor

Question 75

What do we see in evolution about bones?

Answer 75

animals have the same bones in the differnet order but they vary from one another creating different adaptation and advantages for the organism