Lecture 12: Support & Movement

Question 1

What is the location, structure, and function of the skeletal muscle? which branch of the PNS controls these muscles?

Answer 1

Location: attached to the bone above and below joints by strands of collagen (tendons)

Controlled by: efferent neurons of the somatic system of the PNS

Function: skeletal muscles contract and pull on the point of attachment between tendons and bones to stimulate a movement around joints

responsible for VOLUNTARY MOVEMENT & reflexes of appendages

Structure: filaments form a repeating pattern of banding (striation) muscle fibres

Question 2

What is the location, structure, function of the smooth muscle? which branch of the PNS controls these muscles?

Answer 2

Structure: smooth and not striated

Function: INVOLUNTARY activities including peristalsis and constriction of arteries

Controlled by: Autonomic division of the PNS (but all 3 branches of PNS have some control)

Location: in the walls of the digestive tract, bladder, arteries, and other internal organs

Question 3

What is the location, structure, and function of the cardiac muscle? which branch of the PNS controls these muscles?

Answer 3

Location: forms the contractile walls of the heart

Structure: striated

Function: responsible for heartbeat and circulation of blood (and oxygen and circulates CO2 out of the body) throughout the body

Controlled by: Autonomic division of the PNS (sympathetic and parasympathetic)

Question 4

What is the function of the skeletal system? what are the three kinds of skeletal systems in animals?

Answer 4

skeletons provide a rigid structure and points of attachment for muscles to allow an organisms to move

1. exoskeleton
2. endoskeleton
3. hydrostatic

Question 5

T or F: all muscles (except the tongue) will contract when activated?

Answer 5

TRUE, contraction is active

Question 6

Describe exoskeleton, what are the two kinds of exoskeletons? What are advantages and disadvantages?
where do muscles attach?

Answer 6

rigid support system that covers the outside of an animal.
Muscles attach to the internal surface of the skeleton

1. Jointed skeletons: flexible sections around the joints to move appendages (ex. lobsters)
2. Unjointed skeletons: uniformly rigid
   - mostly in sessile organisms (ex. clams, mussels, oysters)

advantages:
- protection
- support
- provides attachment location for muscles

disadvantages:
- growth is a challenge
- jointed skeletons restrict growth so must be shed for organism to grow, leaving organism very vulnerable

Question 7

Describe endoskeleton. What are advantages and disadvantages?

Answer 7

rigid support structure that is located within the soft tissues of an animal
muscles attach to the external surface of the skeleton

advantages:
skeleton grows with the animal

Question 8

Describe how movement occurs in animals that possess a hydrostatic skeleton

Answer 8

not a rigid structure, but a pressurized coelom
- support body with fluid held under pressure in compartments

advantage:

• very flexible and allows animals to easily change shape
• flexibility allows for high escape chances

disadvantage: not much external defense - easily squished

Question 9

Describe how the presence of joints affects movement

Answer 9

Joints are the point at which two or more bones meet

they are responsible for movement by allowing muscles to move bones

Question 10

Describe the origin and insertion points of muscles and how they relate to movement

Answer 10

Origin: the attachment site that does not move during contraction

insertion point: the attachment site that does move during contraction

Question 11

Describe extension and flexion

Answer 11

extension: the limb straightens around a joint through the contraction and relaxation of paired muscles
flexion: the limb bends around a joint through the contraction and relaxation of paired muscles

Question 12

A group of muscle cells is called…?

Answer 12

fibres

Question 13

Describe examples of muscular antagonism in the earthworm

Answer 13

Earthworms have hydrostatic skeletons and use antagonistic action of the longitudinal and circular muscles (pair) pushing against the fluid filled body cavity to move in a straight line

steps:
1. circular muscles contract; longitudinal muscles relax
2. longitudinal muscles contract; circular muscles relax
by contracting and relaxing different muscles in different segments, fluid gets pushed around the body and allows for movement

Question 14

Describe examples of muscular antagonism in the arthropod leg

Answer 14

Arthropods have jointed exoskeletons that have muscles attached to the inner surface

antagonistic contraction of the flexor and extensor muscles (pair) connected to exoskeleton to move appendages around joints/bend and straighten limbs around joints

1. when flexor muscle contracts; extensor relaxes and the limb bends around the joint
2. when flexor relaxes; extensor contracts and the limb straightens around the joint

Question 15

Describe examples of muscular antagonism in the human arm

Answer 15

vertebrates have jointed endoskeletons and the muscles attach to the outer surface of bones by tendons

to bend or straighten limbs around joints, they require antagonistic action of paired muscles –> biceps and triceps of upper arm connect to the radius and ulna bones of the lower arm

antagonistic contraction and relaxation of biceps and triceps allow flexion and extension around the elbow

1. arm is flexed: upper and lower arm brought together and biceps contract; triceps relax
2. arm is extended when the upper and lower arm move farther apart by biceps relaxing; triceps contracting

Question 16

How do muscles provide movement?

Answer 16

By being attached to a skeleton

Question 17

T or F: muscles can only exert force when contracted

Answer 17

TRUE.

Question 18

Define joint

Answer 18

The point at which two or more bones meet

aka an articulation