Biology Form 5 Chapter 2 - Locomotion & support : 2.1 Part 2

1. BIOLOGY FORM 5
CHAPTER 2
LOCOMOTION & SUPPORT
PART 2

2. HUMAN MUSCLE

3. Three kinds of muscle:
Unstriated,
Unstriped
or
Involuntary
Skeletal,
Striated,
Striped or
Voluntary
Cardiac

4. Three kinds of muscle:
1. Smooth Muscle
contracts slowly &
fatigues slowly
2. Cardiac Muscle
is self-stimulating &
does not fatigue
3. Skeletal Muscle
contracts quickly &
fatigues quickly
Gap junctions

5. Tendons attach skeletal muscle to bone:

6. Organisation of Skeletal Muscle
1. Muscle
2. Muscle fibre bundles
[groups of 10-100 or
more muscle fibers]
3. Muscle fibre
4. Myofibril
5. Myofilaments
muscle cell
actin & myosin

7. Organisation of Skeletal Muscle (Fig. 4)
Cells are
multinucleate
Each muscle fibre is composed of MYOFIBRILS

8. Skeletal Muscle Contraction

9. Do the muscles remain stiff forever in a
dead animal?
NO
Eventually the proteins begin to lose
their integrity, and the muscles soften
Dead !!

10. Movement is one of the most distinctive
features of animals
 The nervous
system issues
commands to
the muscular
system
 The muscular
system exerts
propulsive force
against the
skeleton

11. MOVEMENT

12. How does the body move?

13. The skeleton facilitates movement by providing
a framework that muscles can move

14. Types of movement
include:
Walking
Running
Hopping on two appendages
(typically legs)

15. Movement of the skeleton is accomplished by:
the action of pairs of ANTAGONISTIC
MUSCLES: one muscle actively contracts,
causing the other to be passively extended

16. Muscles move the skeleton around
flexible JOINTS
What is a ‘JOINT’?
– the point where two bones meet
What is the function of a joint?
– joints hold bones together, giving stability, yet at
the same time, give the skeleton mobililty
Joint
bones act as levers
that can be moved
by the skeletal
muscles to which
they are attached

17. Not all joints are movable
in those that move, the portion of each bone
that forms the joint is coated with a layer of
cartilage
Immovable joints
(sutures)

18. Function of cartilage at a joint:
its smooth surface allows the bones surfaces
to slide past each other during movement
A synovial
joint

19. What is a ‘Synovial Joint’?
Where articulating bone ends are separated by
a joint cavity and inside is synovial fluid

20. Ligaments & Tendons:
on either side of a joint:
 Tendons attach skeletal muscles to bones
 Ligaments attach the bones together
TENDON
LIGAMENTS
The Elbow

21. Capsule Encloses joints
Ligament Holds the 2 bones
together, prevents
dislocation during
movement
Cartilage Reduces friction,
shock absorber
Synovial
membrane
Produces synovial
fluid
Synovial fluid Lubricant,
minimises friction
between bones
JOINTS

22. Synovial joints are found in all limbs and
allow for various movements.
There are 6 main types of synovial joints:
a) Plane joints (gliding movements i.e. in wrist)
b) Hinge joints (uniaxial movement i.e. in elbow)
c) Pivot joints (rotation movements i.e. radioulnar joint)
d) Condyloid joints (some sideways movements i.e. in
metacarpels)
e) Saddle joints (slight rotation & sideways movements i.e. in
thumb)
f) Ball and socket joints (uniaxial movements & full rotation
i.e. in hip and shoulder)

24. 1. Knee/Hinge joints
Allows movement 1800
Eg in knees, elbows,
phalanges
2. Ball and socket
joints
Allows movement 3600
Rotation in all direction
Eg in hip joint, shoulder
joint

25. Hinge Joints – Synovial Joints
 occur at the elbows, knees
and finger joints
 are movable in only two
dimensions

26. Ball & Socket Joints – Synovial Joints
 allow movement in
several directions

27. The skeleton and muscles interact in
movement
Muscles pull on bones, which act as levers that
produce movement
– Tendons connect muscles to bone
Antagonistic pairs of muscles produce opposite
movements

28. Action of extensor & flexor
Biceps: Flexor [bends arm on contraction]
Triceps: Extensor [extends arm on contraction]

29. Which muscle is pulling on the bone?
BICEPS
TRICEPS

30. Muscles Can Only Contract
 The skeleton and muscles work together in lever systems
 Muscles can only shorten by contraction, they cannot actively
elongate.
 An external force is needed to stretch a muscle back to its
resting length.
 Opposing muscle sets provide this external force.

32. Muscles Involved In Walking
1. The calf
muscle contracts
and raises the
heel.
It pushes the ball
of the foot
against the
ground by
exerting a
forward thrust.
2.The hamstring muscle
contracts to pull the femur
back and bends the knee.
Then the thigh is retracted
and the leg is raised.

33. 3.The weight of the
body is now
supported by the
right leg since the
left foot loses contact
with the ground.
4. The left leg is still in contact
with the ground. The
quadriceps muscle will
contract, pulls the femur
forward and extends the leg.
Then, the thigh is extended.

34. 5. After the
extension of the
legs, the foot
with the heel
touching the
ground first will
regain contact
with the ground
again.
6.The weight of the
body is supported by
the left leg. Now the
whole sequence is
repeated with the right
leg.

35. Consequences of impaired
musculoskeletal system on support
and locomotion
Muscle
Cramps
Osteoporosis
Muscular
Dystrophy
Arthritis

36. Osteoporosis is characterised by low
bone mass
Normal bone
Osteoporosis

37. Osteoporosis

38. Osteoporosis

39. Arthritis

40. Painful joints when:

43. Muscle Cramps
 Involuntary, forcibly contracted muscle, unable to
relax.
 sudden contraction of muscles  sudden great
pain & inability to use the affected muscles.
 spinal cord stimulates muscle to keep contracting.
 cramp lasts from ~ few seconds - 20 minutes or
longer.
 Inadequate stretching and muscle fatigue usually
leads to muscle cramps.
 Common among athletes and older people who
perform vigorous physical activities.

44. Muscular
Dystrophy
 Caused by the progressive degeneration
and weakening of the skeletal muscles which control
movement.
 The body muscles slowly become weak as they
become replaced by fibrous tissues.
 The disease is caused by a mutated
gene in the X chromosome which
mainly affects boys.
 There is no cure for MS.

45. Muscular
Dystrophy

46. THE END