Musculoskeletal system

Question 1

Support structure that provides rigidity to the body, surfaces for muscle attachment, and protection

Answer 1

-Hydrostatic
-muscular hydrostat
-exoskeleton
-endoskeleton

Question 2

Hydrostatic skeletons

Answer 2

-muscular force developed by contracting against fluids
ex)how earthworms (annelids) move, tube feet in echinoderms(sea stars)

Question 3

Muscular hydrostat

Answer 3

-movement achieved via muscle action (no bones, cartilage, or fluid for support): complex muscle arrangments required.
ex) trunks, tongues

Question 4

Exoskeletons

Answer 4

-surrounds the body as a rigid, hard case
-interior surfaces are sites of muscle attachment
-animals must molt periodically to grow
-area/mass ratio does not support large body size

Question 5

Endoskeletons

Answer 5

-internal skeletons to which muscles attach
-made of cartilage and bone both of which are living tissues
-an efficient framework for muscle attachment; continuous growth possible

Question 6

Ball and socket

Answer 6

type of joint
-rotates in two planes
-eg) hip, large range of motion but requires stabilization

Question 7

Hinge

Answer 7

joint type
-move one plane
eg)knee, limited range of motion but stronger and more stable

Question 8

Gliding

Answer 8

joint type
-surface slides
-lateral veterbral joins
-eg)spine, allows flexibility while maintaining alignment

Question 9

Combination

Answer 9

join type
-multiple join types
eg)mammal jaw, important for chewing

Question 10

Limb movement

Answer 10

-muscles exert forces on joints, thereby moving limbs
-because muscles can only contract, muscle arrangement is typically antagonistic(one pulls one way, the other pulls the other.

Question 11

Skeletal muscle(voluntary)

Answer 11

-long, multinucleate, striated cells(vertical lines)
-fast-acting, cerebral control
-attached to skeletal elements (by tendons to bones)

Question 12

Smooth muscles(involuntary)

Answer 12

-long, unstriated(no vertical lines),uninucleate cells
-slow acting; autonomic control
-walls of blood vessels, alimentary canal, ect.

Question 13

Cardiac muscle

Answer 13

-uninucleate, striated cells
-fast acting; autonomic control
-restricted to the heart
-cells function as a single unit(myocardium)

Question 14

Levels of muscle

Answer 14

Bone, tendon, muscles with fascicles (which many muscle fibers, which are made of myofibrils, which are made of myofilaments

Question 15

Myofilaments

Answer 15

Actin-thin filaments(lighter part)
myosin-thick filaments(darker)

Question 16

Striated cells

Answer 16

Striations are the result of the uniform arrangement of myofilaments
-thin filaments are anchored by dense structures called z-lines
-a myofibril unit called a sarcomere, extends between two successive z-lines

Question 17

When does muscle contraction occur

Answer 17

When myofilaments slide past one another, drawing the Z line toward the center of the sarcomere
note that myofilaments do not contract whereas myofibrils do

Question 18

Steps of muscle contraction

Answer 18

1)ADP and P1 attached to myosin head,
2)allows myosin heads to bind to actin,
3)causing the actin head to deform, pulling the actin filament toward the center of the sarcomere. ADP and p1 are released.
4)Binding of new ATP molecule to muslin head to detach the link
5)Cleavge of ATP into ADP+P1 returns head to original shape

MYosin is a motor protein that can convert chemical energy(ATP) into mechanical energy

Question 19

Nerves timulate muscle contractons

Answer 19

Skeletal muscles are under cerebral control,
1)when a motor neuron delivers an electrochemical impulse to a muscle
2)the neurotransmitter acetylcholine is released across synapses. This stimulate muscle to produce an electrochemical impulse
3)impulse is carried into muscle fibers via T tubules
4)impulse stimulates sarcoplasmic reticulum to released Ca++

Question 20

Actin

Answer 20

When muscles are relaxed that means the myosins head cant bind to actin because of
-tropomyosin-blocks myosin heads from binding to actin
-for a muscle to contract, tropomyosin must move out of the way. This is controlled by troponin, a regular protein complex
-When nerves signal muscles to contract, Ca++ is released from the sarcoplasmic reticulum. Ca++ binds to troponin, which alters the configuration of the troponin-tropomyosin complex and allows the myosin head to bind with actin.
Tropomyosin, troponin

Question 21

tropomyosin

Answer 21

tropomyosin-blocks myosin heads from binding to actin

Question 22

troponin

Answer 22

for a muscle to contract, tropomyosin must move out of the way. This is controlled by troponin, a regular protein complex

Question 23

What is needed to break the cross-bridge between actin and myosin?

Answer 23

ATP

Question 24

The size of a muscle response depends on

Answer 24

1) motor unit- a motor neuron plus all the muscle fibers contracted by the axonal branches of the motor neuron
2)The number of motor units recruited- precise contractions require smaller motor units than large forceful contractions
-most muscles contain motor units in a variety sizes which are selectively activated by the nervous system