Skeletal and muscular system

Concept mapping

What is skeleton?

Skeleton: collection of bones that holds our body up.

Baby has 305 bones and an adult has 206 bones

Why ? because as we grown some of our

bones join together to form one bone

Types of skeletons• Exo-skeleton: animals that have

shells

• Endo-skeleton: hard structure inside the animal.

• Hydrostatic skeleton: • Fluid held inside the body

• No skeleton

Five functions of our skeletons1. Protect the vital organs

2. Give us shape

3. Allow us to move because our muscles are attached to our bones

4. Storage of nutrients such as calcium and silicon

5. Formation of blood cells

Human skeletons

Clavicle

Cranium

MandibleScapula

Rib

VertebraInnominateSacrum

Sternum

Humerus

Radius

Ulna

Patella

Tibia

Fibula

Tarsals

CarpalsMeta carpalsFalangsFemur

Metatarsals

X-raysThe tool used to examine bones

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Components of Skeletal System• Bone• Cartilage: three types

– Hyaline– Fibro cartilage– Elastic

Bone Shapes• Long / Pipe

– Ex. Upper and lower limbs

• Short– Ex. Carpals and tarsals,

bones in wrist and ankles

• Flat– Ex. Ribs, sternum,

skull, scapulae• Irregular

– Ex. Vertebrae, facial6-10

Long Bone Structure

• Long bone surrounds by tissues called periosteum

• Under periosteum is tissues called compact bone/ hard bone which contains bone cells, blood vessels, Ca, Phosphorus, and elastic fibers

• Ends of long bone covered by tissues called cartilage

What is bone marrow?

Fatty tissue, located in the cavities in the center of long bones or spaces of spongy bones

Red marrow produce erythrocytes, most of leucocytes and platelets

Yellow marrow produce some leucocytes. It colors is due to the much higher number of fat cells

No diaphysses and not elongated

Compact Bone

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Central or Haversian canals: parallel to long axisPerforating or Volkmann’s canal: perpendicular to

long axis. Both perforating and central canals contain blood vessels. Direct flow of nutrients from vessels through cell processes of osteoblasts and from one cell to the next.

Lamellae: concentric, circumferential, interstitialOsteon or Haversian system: central canal, contents,

associated concentric lamellae and osteocytesOsteocytes. Mature bone cells. Surrounded by matrix Lacunae: spaces occupied by osteocyte cell body Canaliculi: canals occupied by osteocyte cell

processes

Osteocytess

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Bone Histology• Bone matrix. Like reinforced concrete. Rebar is collagen

fibers, cement is hydroxyapetite– Organic: collagen and proteoglycans– Inorganic: hydroxyapetite. CaPO4 crystals

• Bone cells (see following slides for particulars)– Osteoblasts Formation of bone through

ossification or osteogenesis. – Osteocytes – Osteoclasts Resorption of bone – Stem cells or osteochondral progenitor cells

• Woven bone: collagen fibers randomly oriented• Lamellar bone: mature bone in sheets• Cancellous bone: trabeculae• Compact bone: dense

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Bone Matrix

• If mineral removed, bone is too bendable• If collagen removed, bone is too brittle• Extracellular matrix contains mineralization by crystal which

contains Ca, Phosphate, and Carbonate (Hydroxyapetite)

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Cancellouss (Spongy) Bone

• Trabeculae: interconnecting rods or plates of bone. Like scaffolding. – Spaces filled with marrow. – Covered with endosteum.– Oriented along stress lines

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Bone Development cartilages (before born)

Osteoblast (bone forming cells contains Ca and P)

Osteocytes (bone cells)

Osteoclast (destroy bone tissues and release Ca and P in blood circulation)

Chicken Bone ExperimentAim To see what happens to bones when we leave them in acid (vinegar) and water.

This experiment can be set up and left in your classroom for the next four days after which the students will see the results. Students mission is to write up what they think will happen to the chicken bones in each bottle and why?

Materials and Equipment Clean chicken bones ( thigh bones)Two glass jars with lids per groupWaterWhite vinegarPaper towels

PROCEDURE• Place some chicken bones in each jar.• Label one jar with your groups name, date and ‘water’ – add the

bones and water• Label the second jar with your groups name, date and ‘vinegar’ –

add bones and vinegar• Leave the jars for about 3 weeks after which you can remove and

dry the bones on some paper towels• Observe the difference in the two sets of bones

• DISCUSSION• What has happened to each set of bones and why?

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Factors Affecting Bone Growth• Size and shape of a bone determined genetically but can

be modified and influenced by nutrition and hormones• Nutrition

– Lack of calcium, protein and other nutrients during growth and development can cause bones to be small

– Vitamin D• Necessary for absorption of calcium from intestines• Can be eaten or manufactured in the body• Rickets: lack of vitamin D during childhood• Osteomalacias: lack of vitamin D during adulthood leading to

softening of bones– Vitamin C

• Necessary for collagen synthesis by osteoblasts• Scurvy: deficiency of vitamin C• Lack of vitamin C also causes wounds not to heal, teeth to fall

out

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Factors Affecting Bone Growth, cont.

• Hormones– Growth hormone from anterior pituitary. Stimulates

interstitial cartilage growth and appositional bone growth

– Thyroid hormone required for growth of all tissues– Sex hormones such as estrogen and testosterone

• Cause growth at puberty, but also cause closure of the epiphyseal plates and the cessation of growth

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Bone Fractures

• Open (compound)- bone break with open wound. Bone may be sticking out of wound.

• Closed (simple)- Skin not perforated.

• Incomplete- doesn’t extend across the bone. Complete- does

• Comminuted fractures: complete with break into more than two pieces

Joints• Joints are the point were bones meet.

There are two groups, movable and immovable joints

• Ball-and-socket joints- formed when a rounded head of one bone fits into the rounded cavity of an jointed bone.

• Hinge joints-would include elbow, knee, ankle, and fingers. Allows extension and retraction of apendage

• Sadle joints- A saddle joint allows movement back and forth and up and down, bot does not allow for rotation like a ball and socket joint.

• Gliding joints- In a gliding or plane joint bones slide past each other. Midcarpal and midtarsal joints are gliding joints.

• Pivot joints- allow limited rotation or turning of the head

• Ellipsoidal joints- bone in wrist, and a oval shaped part that fits in a curved space, the joints slide over each other

Functions of the Muscular System Involuntary

Some involuntary functions of the muscular system are muscles to help you breathe, make your heart beat, and help move food through

the digestive system. Voluntary

Some voluntary functions of the muscular system are like playing piano, running, playing video games, and throwing a ball.

MusclesMusclesAn organ that can contract to become shorter

MusclesAn organ that can contract to become shorter

Cardiac Muscle

• One, centrally located nucleus• Presence of striations• Short, branched cells• Presence of intercalated discs• “involuntary”• Myogenic (contraction originates within the muscle

cell)• Does not fatigue

Skeletal Muscle• Many, peripherally located nuclei (develops from many

myoblasts)• Presence of striations• Long (up to 30 cm), thin cells• “voluntary”• Neurogenic (contraction is initiated my motor neuron

input)• Can fatigue

Smooth Muscle

• One, centrally located nucleus• No striations• Short, tapered cells• “involuntary”• Myogenic with some neurogenic modulation• Does not fatigue

• Synergists = muscles that work together to produce certain movements (ex. Multiple arm muscles are needed for flexion of the antibrachium)

• Antagonists = muscle(s) that work(s) to oppose certain actions = moves the structure in the opposite direction (ex. Triceps brachii is an antagonist to the biceps brachii and causes extension of the antibrachium)

• Muscles consist of a ––Belly = the region with the muscle fibers–Tendon = connective tissue at the ends of the

muscle that is continuous with the muscle and the connective tissue layer of the bone to which the muscle attaches

–Fascia = connective tissue layer that surrounds the muscle

FracturesJoints

Dislocation- is when the ligaments attached to the bone are torn or out of place

Torn cartilage- is a sharp blow or twisting of the joint

Arthritis- inflammation of the joint and is a result of natural wear and tear

Fasiculus = a bundle of muscle fibers, many per muscle

Muscle Fiber = a single muscle cell

Epimysium (fascia) = connective tissue layer that holds many fasiculi together, with the associated nerves, arteries and veins, to form a muscle (an organ)

Perimysium = connective tissue layer that surrounds and produces a fasiculus

Endomysium = connective layer surrounding a single muscle fiber

Microscopic anatomy of muscle cells

Sarcomere = smallest contractile unit in a muscle fiber; extends from Z-line to Z-line

A (anisotrophic band) band = “without change band” = at low magnification it looks the same regardless of the contractile state of the muscle; contains thick myofilaments overlapped with thin myofilaments

I (isotrophic band) band = “with change band” = density changes at low magnification depending upon the contractile state of the muscle; at rest, contains only thin myofilaments

Z-lines = dense regions at the ends of sarcomeres, serve as sites of thin filament attachment

H-zone = region in the middle of the A-zone that at rest contains only thick filaments

Muscular Contraction• Impulse from nervous system

Sliding Filament Theory of Muscular Contraction

Muscle contraction occurs when thick (myosin) and thin (actin) myofilaments are allowed to interact; thin filaments “slide” along thick filaments to the center of the sarcomere, thus shortening the contractile unit

1. Gastrocnemius2. Sartorius3. Deltoid4. Sternocleidomastoid5. Tibialis 6. Hamstring group7. Rectus Abdominus8. Triceps 9. Biceps 10. Extensor Group