Learning Strand 2: Scientific Literacy and Critical Thinking Skills

1. THE MUSCULAR
SYSTEM
PART I
LEARNING STRAND 2
Michael Cachero Gelacio / Teacher III – District I ALS Coordinator

2. LET’S SEE WHAT YOU ALREADY KNOW
To find out what you already know about the topics to be discussed, answer the
questions below. Write your answers in a ½ crosswise sheet of paper.
1. Enumerate the seven functions of the muscular system.
2. Name the two major types of muscles that make up the muscular system.
3. Describe how the muscular system works during movement.

3. HOW THE MUSCULAR SYSTEM
FUNCTIONS

4. MUSCULAR SYSTEM
Composed of muscles that are arranged in
a way that enables you to move and do a
lot of things.
An adult has 620 identified muscles. This
figure only represents the skeletal
muscles, the muscles that are attached to
bones.

5. MUSCULAR SYSTEM
Muscles are living tissues that have
the special ability to contract or
shorten, thus producing movements
of internal and external body parts.
Muscles attach two bones to each
other through TENDONS.

6. SKELETAL MUSCLES
The skeletal muscles of the muscular
system are attached to the bones of the
skeletal system of the human body. These
allow the body to move and accomplish a
lot of things.
You need your muscles to jump.

7. SKELETAL MUSCLES
You use your leg muscles to run.
You use your facial muscles to smile and express happiness.

8. FUNCTIONS OF
SKELETAL MUSCLES
1. VOLUNTARY MOVEMENTS OF THE BODY
2. PROVIDE PROTECTION TO THE INTERNAL
ORGANS.

9. FUNCTIONS OF
SMOOTH MUSCLES
Feel very smooth and lack the
rough appearance of other kinds
of muscles.
3. FACILITATING THE MOVEMENT
OF INTERNAL ORGANS.

10. KINDS OF
SMOOTH MUSCLES
It pumps blood throughout your body. The
muscles found in the heart are called
CARDIAC MUSCLES.
HEART

11. SMOOTH MUSCLES
The smooth muscles of the stomach
contract to digest food.
DUODENUM

12. SMOOTH MUSCLES
The smooth muscles of
your intestines allow
food to be digested
and propelled towards
the anus.
INTESTINES

13. SMOOTH MUSCLES
The smooth muscles of the Uterus
contract to allow females to deliver a baby.
UTERUS

14. SMOOTH MUSCLES
The smooth muscles of your bladder
and ureters control urination.
URETHRA

15. SMOOTH MUSCLES
When you inhale, your diaphragm
contracts pulling your lungs down
and making them expand or inflate
to allow air to enter.
When you exhale, your diaphragm
relaxes, making lungs deflate. The
deflation of your lungs allows air to
exit from your body.
DIAPHRAGM

16. FUNCTIONS OF
MUSCULAR SYSTEM
4. MUSCLES PROVIDE HEAT THAT THE
BODY NEEDS TO FUNCTION PROPERLY.

17. The muscular system is a system of voluntary and involuntary muscles in the human
body. It greatly contributes to the well-being of the body by:
1. allowing movement to occur;
2. providing protection to internal organs;
3. facilitating the movement of internal organs such as the heart, lungs, intestines
and bladder to function properly; and
4. producing heat that the body needs to function properly.
♦ Muscles produce movement by contracting or shortening.
 Some actions of the muscular system are voluntary as in the case of the skeletal
muscles that are attached to the bones of the body.
 Some are involuntary as in the case of the smooth muscles especially the muscles
lining the walls of the intestines

18. LET’S SEE WHAT YOU HAVE LEARNED
DIRECTION: Write True in the blank if the statement is correct. Write False if it is not.
________1. The human muscular system is made up of different kinds of muscles.
________2. Muscles only move voluntarily.
________3. Muscles are able to work because of their strength.
________4. Contraction of the smooth muscles allows the body to move.
________5. The muscular system makes movement possible through a series of contractions.
________6. The muscular system provides some protection to vital organs like the intestines
and the stomach.
________7. Life as we know it is still possible without the muscular system.
________8. Childbirth is made possible by the contraction of the uterus.
________9. The muscular system does not provide heat to the body.
_______10. Shivering is the body’s own way of producing heat.

19. STRUCTURE OF THE MUSCULAR
SYSTEM
An adult has 620 skeletal muscles arranged in the best possible way to make
parts of the body move.
In males, the skeletal muscles make up 42% of the adult body weight.
In females, who are less heavy generally, skeletal muscles comprise 36% of
their entire body weight.

20. STRUCTURE OF THE MUSCULAR
SYSTEM
The skeletal muscles are so
named because they are
closely associated with the
skeletal system.
The skeletal system is made up
of bones that form the
foundation and give shape to
the human body

21. STRUCTURE OF THE MUSCULAR
SYSTEM
The skeletal muscles act like the
walls of a house, which connect
bones to each other.
Although the bones are already
connected to each other by tough
fibrous bands of tissue called
ligaments, THE SKELETAL MUSCLES
REINFORCE THESE CONNECTIONS
AND MAKE THEM STRONGER.

22. STRUCTURE OF THE MUSCULAR SYSTEM
Muscles are attached to at least two bones in
at least two points, one on each point.
These points are called the ORIGIN and
INSERTION.

23. STRUCTURE OF THE MUSCULAR SYSTEM
There are also complicated muscles in the
body which have three or more bone
attachments!
These attachments are needed to provide
more stability to the movement of the bones.
This is especially needed for work requiring
more effort like lifting weights.

24. STRUCTURE OF THE MUSCULAR SYSTEM
The biceps and triceps muscles are ANTAGONISTIC MUSCLES or opponent
muscles . Antagonistic muscles are located opposite each other.

25. STRUCTURE OF THE MUSCULAR SYSTEM
SYNERGISTIC MUSCLES are groups of muscles
work together to perform a similar action.

26. LET’S SEE WHAT YOU HAVE LEARNED
DIRECTION: Write True in the blank if the statement is correct. Write False if it is not.
______ 1. There are 320 skeletal muscles in the human body.
______ 2. The skeletal muscles move voluntarily.
______ 3. All muscles are of the same size.
______ 4. All muscles are of the same shape.
______ 5. Skeletal muscles are attached to bones.
______ 6. Tendons attach muscles to bones.
______ 7. Muscles primarily work by contracting.
______ 8. Contracting one’s muscles makes bones move away from each other.
______ 9. The triceps and biceps of the upper arm are examples of synergistic muscles.
______ 10. Opponent muscles contract at the same time.

27. SMOOTH MUSCLES
Smooth muscles are made up of a special
form of muscle tissue under AUTOMATIC
CONTROL OF THE NERVOUS SYSTEM.

28. SMOOTH MUSCLES
These are involuntary muscles that
mediate functions such as circulation,
digestion, urination and reproduction,
which are necessary for living and the
continuation of life.

29. STOMACH MUSCLES
The stomach is the part of the digestive
system found in the abdomen.
It functions primarily to digest food
through the secretion of acids. When the
smooth muscles of the stomach contract,
food is pushed towards the intestines to
continue the process of digestion until it is
finally expelled.
This process is called PERISTALSIS. Without
peristalsis, digestion of food will not be
possible.

30. WHAT HAVE YOU LEARNED
Match the items in Column A to those in Column B. Write the answers in the space provided.
Column A Column B
____ 1. Voluntary muscles a. One of the functions of muscles
____ 2. Cardiac muscles b. Move under conscious control
____ 3. Involuntary muscles c. Produce movement even without one’s knowledge
____ 4. Movement d. Muscles attached to bones
____ 5. Contraction e. Muscles of the heart
____ 6. Antagonistic muscles f. Cause muscles to move
____ 7. Heat production g. Make up internal organs
____ 8. Smooth muscles h. Opponent muscles
____ 9. Synergistic muscles i. Role of muscles in regulating movements
____ 10. Skeletal muscles j. Muscles that contract together

31. THE MUSCULAR
SYSTEM
PART II
LEARNING STRAND 2

32. LET’S SEE WHAT YOU ALREADY KNOW
To find out what you already know about the topics to be discussed, answer the
questions below. Write your answers in a ½ crosswise sheet of paper.
1. Enumerate the three major types of muscle tissues.
2. What is the basic contractible unit of muscles?
3. What makes cardiac muscles different from skeletal and smooth muscles?
4. State three injuries or diseases that can affect the muscular system.
5. Cite two ways to take good care of the muscles of your body.

33. THE MUSCLE TISSUE
Muscles are made up of fibers that have two very
special properties.
1. EXCITABILITY. Refers to the muscles’ ability to
respond to electrical signals provided by the
nerves of the nervous system.

34. THE MUSCLE TISSUE
2. CONTRACTION enables the body to make
both internal and external movements.
Contraction involves shortening of the muscle
fibers.

35. TWO TYPES OF MUSCLES
1. VOLUNTARY MUSCLES
Muscles that are under conscious control
and produce voluntary movements by
pulling against the bones of the skeleton
to which they are attached by means of
TENDONS.

36. VOLUNTARY MUSCLES
THE SKELETAL MUSCLES
In terms of performance, they are like high-
speed engines. They work fast and powerfully
but easily get tired because of the high
amounts of energy needed to make them
move.
Skeletal muscles are also called STRIATED
(striped) muscles because if seen under a
microscope, their individual fibers are visible.

37. VOLUNTARY MUSCLES
The skeletal muscles are HIGHLY
VASCULAR. This means they are rich in
blood supply needed for the fast, powerful
movements of the body.
Skeletal muscle cells are cylindrical in
shape. They are also very long.

38. VOLUNTARY MUSCLES
MYOFIBRIL = individual fiber in a
bundle.
SARCOLEMMA = A group of myofibrils
when enclosed in a membrane. The
word sarco means “flesh” in Latin.

39. VOLUNTARY MUSCLES
A BANDS = dark bands
I BANDS = light bands. Have thin
lines traveling through the center
of a myofibril called Z lines.
SARCOMERE = area between two
Z lines, the contractile unit of the
myofibril.

40. VOLUNTARY MUSCLES
MUSCLE FIBER = myofibrils that are
packed together as a single unit inside
the sarcolemma.
MUSCLE FASCICULI (plural of fasciculus)
muscle fibers that are packed together
in bundles.
MUSCLE = Groups of muscle fasciculi.

41. MUSCLE MOVEMENT
Movement is achieved through a complex
series of protein interactions inside each
sarcomere, the basic contractible unit of
a muscle.

42. LET’S REVIEW
Write the letter of the description in Column B that matches the word or phrase in Column A
Column A Column B
_____1. Voluntary muscle a. basic contractible unit of the muscular system
_____2. Striated b. rich in blood supply
_____3. Muscle fasciculus c. muscle movement
_____4. I band d. skeletal muscle cell
_____5. Contraction e. dark band
_____6. Sarcolemma f. muscle bundle
_____7. Sarcomere g. comprised mostly of skeletal muscles
_____8. A band h. light band
_____9. Vascular i. striped in appearance
____10. Myofibril j. covering membrane of myofibrils

43. TWO TYPES OF MUSCLES
2. INVOLUNTARY MUSCLES
are the muscles that are not under
conscious control. They are also called
smooth muscles.

44. INVOLUNTARY MUSCLES
The smooth muscles can be found in
hollow VISCERA or internal organs
such as the stomach, intestines,
bladder, uterus, walls of the blood
vessels, glands and even skin.

45. INVOLUNTARY MUSCLES
The smooth muscles do not appear
striated when seen under a
microscope.
Internal organs need to create
sustained, prolonged movements that
are less powerful and thus have no
need for striations except for the heart.

46. INVOLUNTARY MUSCLES
The only INVOLUNTARY MUSCLE that is
striated is the heart.
The heart pumps blood throughout the body
24 hours a day, seven days a week without
fail.

47. INVOLUNTARY MUSCLES
CARDIAC MUSCLES
Have dark stripes called INTERCALATED DISKS.
These disks mark the points of strong adhesion
between the cells of the cardiac muscles which
must withstand strong pressures during
contraction.

48. LET’S SEE WHAT YOU HAVE LEARNED
Answer the following questions briefly.
1. What are the two general classifications of muscles? Differentiate one from the other.
2. Why are voluntary muscles striated? Explain your answer.
3. How are cardiac muscles similar to skeletal muscles? How are they different? Explain your answers.
4. Why are cardiac muscles, though involuntary, striated? Explain your answer.

49. COMMON DISEASES
AND INJURIES
LEARNING STRAND 2

50. MUSCLE STRAIN
The muscular system, tough as it is, is still prone to diseases. It needs to be taken care
of too! The following are some of these injuries and diseases.
is a tear or stretch in the muscle fiber or
the tendon that connects a muscle to a
bone.
It can range from a relatively mild injury,
with some muscle fibers being torn, to a
large muscle tear with swelling and
bleeding.

51. MUSCLE STRAIN
Muscle strains are usually caused by:
1. MUSCULAR IMBALANCE – This occurs when
one side of the joint is stronger than the
other or the opposite muscle does not relax
while the other contracts. This can be traced
in most cases to either a lack of conditioning
or overtraining one muscle group versus an
opposing muscle group, e.g., the front of the
thighs (quadriceps) versus the back of the
thighs (hamstrings).
2. MUSCLE FATIGUE – This occurs when
additional stress is put on a muscle and its
connective tissue.

52. MUSCLE STRAIN
The more active a person is, the greater his/her risk of injury. Poorly conditioned
people are also at risk when they do strenuous activities without proper
preconditioning.
The following are the signs/symptoms of
muscle strain:
1. Pain in a muscle group or joint;
2. Swelling of a muscle group or joint; and
3. Tenderness in a muscle group or joint.

53. FIRST AID TIPS FOR MUSCLE STRAIN
1. Reduce your activities. Avoid movements that place stress on the injured area.
2. Apply a cold compress or some ice on the injured area. Do this for 24 to 48 hours after the injury.
3. You may try applying a hot compress or an analgesic balm on the injured area on the third day or as
soon as the swelling is gone.
4. Apply an elastic bandage to the injured area.
5. Elevate the injured area for 24 to 48 hours depending on the severity of the injury.
6. Taking in aspirin may also help reduce the pain and inflammation. Just be sure to use it as directed.
7. Try slow gentle stretches. Avoid stretching for a few days if the injury is severe; do movements that
promote circulation instead, e.g., slow walking, gentle arm rotation exercises, etc.
8. Be sure to properly condition your body first before doing strenuous activities next time.
9. Strengthen major muscle groups with weight training.
10. Consult a doctor if:
a. there is excessive swelling, bruising and/or tenderness in the injured area;
b. the pain prevents you from moving.

54. MUSCLE SPASMS OR CRAMPS
Contractions of the muscles which are
often painful.
Muscle twitching is the result of minor
local muscle contractions or the
uncontrollable twitching of a single
muscle group served by a single motor
nerve fiber or filament.

55. MUSCLE SPASMS OR CRAMPS
Muscle spasms or cramps are commonly
caused by:
1. muscle fatigue;
2. heavy exercise;
3. dehydration; and
4. pregnancy.

56. MUSCLE SPASMS OR CRAMPS
Muscle twitching can be caused by:
1. a benign (of a mild form), non-pathologic (not caused by disease or disorders)
fasciculation which:
a. often affects the eyelids, calf or thumb; and
b. is normal or common and is often triggered by stress and anxiety;
2. a diet deficiency;
3. drug overdose; and
4. a side effect of taking in drugs such as diuretics (drugs that increase the
volume of urine produced and excreted), corticosteroids (steroid hormones)
and estrogens (steroid hormones, produced mainly by the ovaries, that control
the growth and functioning of the female sex organs and the appearance of
female secondary sexual characteristics).

57. MUSCLE SPASMS OR CRAMPS
Muscle cramps most often occur in the foot or calf muscles. Muscle twitches are
minor and often go unnoticed. Some are common and normal while others indicate
a neurologic disorder. The following are some first-aid treatments for muscle
cramps:
1. slow stretching exercises;
2. following prescribed therapy; and
3. taking in prescribed analgesics or pain relievers.
But you should consult your doctor if:
1. there are severe, prolonged or recurring muscle spasms or cramps that are
unexplained or that aren’t relieved by simple stretching exercises; and
2. there are prolonged or persistent muscle twitches that are unexplained.

58. POLIOMYELITIS
what is commonly known as polio is a
disorder caused by a viral infection
(poliovirus) that affects the whole body
including muscles and nerves.
Severe cases may cause permanent
paralysis or even death.
It is usually manifested by loss of muscle
tone and bulk. People with polio usually
have unequally sized legs which cause
impaired movement.

59. POLIOMYELITIS
Communicable disease caused by infection with the poliovirus
Transmission of the virus occurs by:
A
B
C
direct person-to-person contact
by contact with infected secretions from the nose or mouth
by contact with infected feces

60. THREE BASIC PATTERNS OF POLIO
1 SUBCLINICAL INFECTIONS - are infections that may go unnoticed. These have no symptoms
or if they do, the symptoms last for only 72 hours or less. These said symptoms include:
slight fever
headache
malaise (general discomfort or uneasiness)
sore throat
vomiting
A
B
C
D
E

61. THREE BASIC PATTERNS OF POLIO
2 NONPARALYTIC POLIOMYELITIS - may occur after recovery from a subclinical infection.
Its symptoms may last for one to two weeks. These include:
moderate feverA
headacheB
stiff neckC
vomitingD
diarrheaE
back painF
irritabilityG
pain or stiffness of the back, arms, legs and abdomenH
muscle tenderness and spasm in any area of the bodyI
neck painJ
fatigue or excessive tirednessK
leg pain (especially in the calf muscles)L
painful skin rash or lesionM

62. THREE BASIC PATTERNS OF POLIO
3 PARALYTIC POLIOMYELITIS – This may occur after recovery from subclinical infections.
Its symptoms include :
fever, occurring five to seven days before the other symptomsA
headacheB
stiff neck and backC
muscle weakness characterized by rapid onset which can progress to paralysis depending on
where it affects the spinal cord
D
abnormal sensations of an areaE
oversensitivity to touchF
difficulty in urinatingG
constipationH

63. THREE BASIC PATTERNS OF POLIO
bloated abdomenI
difficulty in swallowingJ
muscle painK
muscle contractions or spasms particularly in the calf, neck or backL
droolingM
difficulty in breathingN
irritabilityO
positive Babinski’s reflexP

64. The occurrence of polio may be prevented by POLIO IMMUNIZATION (VACCINE)
The goal of
treatment is to
control
symptoms while
the infection
runs its course
Antibiotics may be used to treat
urinary tract infections
Medications such as bethanecol
(may reduce urinary retention)
analgesics (may reduce headache,
muscle pain and spasms)
Narcotics which are not usually given because
they increase the risk of breathing difficulty.
Moist heat (heating pads, warm towels, etc.) may
also reduce muscle pain and spasms. Physical
therapy, braces or corrective shoes, orthopedic
surgery or similar interventions may eventually
be necessary though to maximize the recovery of
muscle strength and function
#1
#2
#3
#4

65. The following are some of the complications that may develop from polio
Spread of
infection to
other non-
immune people
Permanent
muscle
paralysis,
disability or
deformity
Pulmonary
edema (a
condition
characterized by
fluid
accumulation in
the lungs
caused by back
pressure in the
lung veins)
Shock
Complications
of immobility
and respiratory
involvement
such as:
Aspiration
Pneumonia
Hypertension
Urinary Tract
Infections
Kidney Stones
A B C D
E
Paralytic Ileus

66. MYOCARDITIS
(inflammation
of the
myocardium or
the muscular
tissue of the
heart)
COR
PULMONAE
(enlargement of
the right
ventricle that
occurs because
of pulmonary
hypertension
from lung
disorders)
F G

67. To avoid the
diseases and
the
complication
s mentioned
beforehand,
be sure to
consult your
doctor if:
Symptoms of poliomyelitis occur
Someone close to you has developed
poliomyelitis and you are not immunized
against the disorder
If your child’s polio immunization vaccine is
not up-to-date
#1
#2
#3

68. CARING FOR YOUR
MUSCULAR SYSTEM
LEARNING STRAND 2

69. EAT A LOT OF PROTEIN-RICH FOODS SUCH AS SOYA
BEANS, VEGETABLES, MEAT AND FISH

70. AVOID ACTIVITIES THAT MAY CAUSE INJURIES SUCH AS
CLIMBING ON TOP OF UNSTABLE FURNITURE

71. ALWAYS WEAR OR USE PROTECTIVE EQUIPMENT WHEN
DOING SOMETHING THAT MIGHT BE DANGEROUS

72. EXERCISE REGULARLY TO MAKE YOUR MUSCLES
STRONG

73. KEEP THINGS IN ORDER. PLAYTHINGS LEFT ON THE
STAIRS OR ELSEWHERE MAY CAUSE ACCIDENTS

74. REST EVERY NOW AND THEN WHILE WORKING TO
ALLOW YOUR MUSCLES TO RELAX

75. LIFT WEIGHTS PROPERLY. AVOID BENDING FORWARD
WHEN CARRYING HEAVY LOADS

76. ALWAYS SEEK MEDICAL ADVICE WHEN AN INJURY TO
MUSCLES OR TENDONS OCCURS, JUST TO BE SURE

77. MAINTAIN PROPER HYGIENE ALWAYS

78. LET’S SEE WHAT YOU HAVE LEARNED
Fill in the blanks with the correct answers.
___________ 1. A tear or stretch in the muscle fiber or the tendon that connects a muscle to a bone
___________ 2. Occurs when one side of the joint is stronger than the other or the opposite muscle does not
relax while the other contracts
___________ 3. Occurs when additional stress is put on a muscle and its connective tissue
___________ 4. A contraction of a muscle which is often painful
___________ 5. The result of minor local muscle contractions or the uncontrollable twitching of a single
muscle group served by a single motor nerve fiber or filament
___________ 6. Commonly known as polio
___________ 7. Infections that may go unnoticed
___________ 8. A reflex where the great toe flexes toward the top of the foot and the other toes fan out
when the sole of the foot is firmly stroked
___________ 9. A condition in which the blood pressure is abnormally high
__________ 10. Help build muscles and are needed for them to function properly