Musculoskeletal system

Musculoskeletal System Provides

Supports upright posture

Provides wide range of motion / movement

Protects internal organs

Carries weight

General types of skeletons

Hydrostatic skeleton, Exoskeleton, Endoskeleton

The hydrostatic skeleton is formed by a

fluid-filled internal compartment, called the coelom

The coleum is under

hydrostatic pressure -- fluid, supports the organism and organs

A Hydrostatic skeleton is found in

soft-bodied animals such as sea anemones, earthworms, starfish, and other invertebrates

Movement in a hydrostatic skeleton

Muscle contraction and relaxation changes the shape of the coelom, pressure on the fluid produces movement.

An Exoskeleton is

External, consists of a hard encasement covering

An Exoskeleton provides

Provides defense and support the body

An Exoskelton is made of

30-50% chitin (polysaccharide); acellular

An exoskeleton allows for movment

through the contraction of attached muscles on the inside

Arthropods have a

exoskeleton (crustaceans and insects)

If you have an exoskeleton you have to

Molt to grow - shed exoskeletons because the exoskeleton does not

expand/grow

An Endoskeleton is

Hard, mineralized structures located within the soft tissue of

organisms

An endoskeleton is made up of

50 - 70% mineral

• 20 – 40% organic

• 5 – 10% water

• 3% lipid

An endoskeleton provides

support, protects internal organs, and allow for movement through contraction of muscles attached to the skeleton

The 2 divivsions of human endoskeletons are

Axial skeleton and Appendicular Skeleton

The axial skeleton consists of the bones of the

Skull

Ossicles of the middle ear

Hyoid bone

Vertebral column

Thoracic (rib) cage

The apendicular skeleton is made up of

SHoulder girdle

Arms

Hands

Pelvic girdle

Leg

Foot

Skull bones support

Support the structures of the face and protect the brain

Auditory Ossicles

Transmit sound from air to cochlea smallest bones in the body

• Malleus

• Incus

• Staples

Hyoid Bone

Provides attachments for the muscles of the tongue, larynx (voice-box), and mandible (lower jaw)

The hyoid is important in

speech and swallowing

The hyoid bone is the only bone that

does not articulate with any other bone

The vertebral column is made up of

Cervical vertebrae (C1–7)

Thoracic vertebrae (Th1–12)

Lumbar vertebrae (L1–5)

Sacrum (5 fused)

Coccyx (4 fused)

The curve inscreases strength/Flexibility

The thoracic cage

or rib cage, protects the heart, lungs, pancreas, liver, and spleen.

The pelvic girdle

To adapt to reproductive fitness, the (a) female pelvis is lighter, wider, shallower, and has a broader angle between the pubic bones than (b) the male pelvis

Bone Type: Flat

protects organs; sternum, skull

Bone types: Irregular

complex shape; vertebra

Bone type: Long

contains bone marrow; femur

Bone type: Sesamoid

sesame seed shaped – patella, small bones of hands and feet, enclosed in ligaments

bone type: short

cuboidal shaped; wrist and ankle bones

bone type: sutural

small, flat, irregular; between flat bones of skull

Osteon

Unit of bone

The haversion canal in osteon

is made up of vessels and nerves

Lamella

round layer of bone in osteon

lacuna

a small, microscopic cavity within the bone tissue that houses an osteocyte, a mature bone cell

osteocyte

bone cell in lacuna

caniculi

small canals where they connect osteocytes in lacunae for communication and nutrient exchange

osteogenic cell

bone stem cell

osteoblast

forms bone matrix

osteocyte

maintains bone tissue

osteoclast

reabsorbs bone

trabeculae

spongy bone

spongy bone is shaped like

rods and plates and triangles

sppongy bone id

light weight but strong

Ossification (Osteoblast)

Calcification –

begins 6M in utero and continues for 25

years for length, lifetime for thickness

Intramembranous Ossification

Ossification

of fibrous membranes into skull, mandible, clavicle – Ossification via mesenchymal cells – embryonic connective tissue

Endochondral Ossification

Mesenchymal(bone stem) cells differentiate

into osteoblast, leads to ossification of cartilage - All other bones

Bone Growth

Bones grow in length at the Epiphyseal plate

Growth is under control by

growth hormones produced by the pituitary gland as well as the

Ovaries and testes

Remodeling

Old bone replaced by new bone

Repair

healing a broken bone

hematoma

collection of clot

callas

fibruous tissue and cartilage

ossification

via osteoblas

osteoblast function

deposition of new bone

Osteoclast function

reabsorption of old bone

remodeling happens via

osteoclast + osteoblast

Joints and skeletal movement are classified by

Basic structure- the material and how the bones are connected

fibrous connection

connection by fibrous connective tissue

• No or little movement

cartilaginous

connection by cartilage

• More movement than Fibrous

synovial

Synovial capsule – space between bones

• Excellent movement

planar joint

wrist/ankle

hinge joint

elbow, kneee

pivot joint

neck

condyloid joint

thumb

saddle joint

hand

ball and socket

hip and shoulder

tendon

attaches muscle to bone

ligament

connects bone to bone or cartilage to cartilage

muscle cells are

specialized for contraction

skeletal muscle cell

Attach to bones and skin, locomotion and movement,

voluntary, long and cylindrical, striated, multiple nuclei

cardiac muscle cell

Heart muscle, striated, single nucleus, involuntary

smooth muscle cell

Walls of hollow organs (digestive system, blood vessels

respiratory system, bladder), no striations, involuntary, single

nucleus

sarcolemma

the plasma membrane that surrounds a skeletal muscle cell

sarcoplasm

the cytoplasm in myocyte

myofibrils

small subsection of myocyte; contractile filaments

myocyte striations

bands of proteins: Actin and Myosin