MUSCLES AND BONES

Bone

• is a connective tissue in which the cells and fibers are embedded in a matrix (ground substance) 

Osteocytes

Resifing in lacunae taping processes embedded in ground substance

Hydroxypatite

• that contains curtail of complex calcium salt 

Supportive and protective

Functions of bones

Medullary Cavity

• there’s space to be light weight 

Periosteum

covers the outer surface

of bones

endosteum

thinner layer, lines theinterior of the bones

Substantia compacta

dense bone surrounding voluminous central

medullary cavity or marrow cavity

Substancia spongiosa

this is what happens to the compact bone as it

approaches the end of the diaphysis. They

become thinner and the medullary cavity

spicules

Branching bone of medullary cavity (Trabeculae)

Articular cartilage

thin hyaline cartilage that

covers the end of long bones when it forms a

joint with another bone

Epiphyseal plate

thin zone of hyaline

cartilage, separates the diaphysis from a short

segment of long bones of growing children,

Epiphysis

Either end of epiphyseal plate

Outer and inner table

In flat bones of skull, compact bone forms outer

and inner layer, referred to as

Diploe

Corresponding to medullary cavity of

long bone

Osteoprogenitor cell

fusiform shaped cell found in the periosteum

and endosteum.

- Cells are inactive precursors of the

osteoblasts

Osteoblasts

cuboidal, low columnar cells

aligned on bone surfaces. They synthesize type

I collagen glycoproteins, and proteoglycans of

the ground substance, and several minor

proteins (osteocalcin, osteonectin, osteopontin

and osteoproteregin)

Osteoclast

highest remodeling and renewal

- very large cell up to 15 micrometer in diameter

and contains 4 to 40 nuclei. They are involved

in internal remodeling and renewal of bone.

Howship’s lacuna

Beneath each osteoclast there is a shallow

depression on the surface of the bone and it is

called

Haverisan system

compact

bones of adults is made up of cylindrical

subunits

Osteons

5-6 rings lamellae of calcified matrix

arranged around a central canal

Volkmann’s canals

oblique channels that

pass through lamellae that connects the

central canal of the osteons or to t marrow

cavity

Interstitial lamella

parallel lamellae that

occupies the angular areas between the

osteons

Cement line

thin refractile layer that lines the

outer boundary of each Haversian system or

osteon

Outer circumferential lamellae

just beneath

the periosteum.They go around the entire

circumference of the shaft without interruption.

Internal circumferential lamellae

Comparable

lamellae beneath the endosteum are called

Intramembranous ossification

when bone is

bone is formed by replacing the primitive tissue

Endochondral ossification

bone formation

takes place in pre-existing cartilage. Occurs in

long bones of appendicular skeleton

Producing movement

● Maintaining posture

● Stabilizing joints

● Generating heat

Functions of muscle tissue

Skeletal muscle

Voluntary

Striations

Rapid but tires easily

Attaches and covers the bony skeleton

Skeletal muscle

Attached to bones to skin, single very long cylindrical multinucleared with obvious striations

Cardiac muscle

Branching chains of cells, uni or uncleared striations

Smooth muscle

Single fusigorm uninucleated no striations, hollow

Cardiac

Involuntary

Striations

Usually steady rate

Heart

Smooth muscle fibers

Involuntary

No Striations

Slow and sustained

Walks of follow visceral organs

Intercalated disks

Found in cardiac muscle

Sarcolemma

1 long

cylindrical cell multiple oval nuclei

arranged beneath

● Diameter : 10-100 um

Sarcoplasm

contains large amounts

of glucosomes and myoglobin

Myofibrils

Each muscle fibers

contains of hundred to thousands

● Contractile element

●

Striations

repeating series of dark

bands and light bands that are nearly

perfectly aligned with one another

A band

Dark band

I band

Light band

H zone

light zone in midsection of A

band

M line

bisects the H zone

Z line (disc)

bisects the I band

Sarcomere

Region of a myofibril

between two successive Z discs

● Contains an A band flanked by half an I

band at each end

● Smallest contractile unit of a muscle

● Each myosin molecule has:

● Rodlike tail consisting of two

interwoven helical polypeptide chains

● • Two globular heads which contain

ATPase enzymes - split ATP to

generate energy during contraction

fiber (ave. 2 um long)

Myosin

Thick filaments

Actin

Thin filaments

Rodlike tail

Myosin molecule has ___ consisting of two interwoven helical polypeptide chains

Two globular heads

Contain ATPase enzymes that split ATP to generate energy during contraction

G Actin (globular)

Polypeptide subunits of actin

(globular actin) contain the active sites

to which myosin heads attach during

contraction

Sarcoplasmic reticulum

Composed of interconnecting tubules

that surround each myofibril

Terminal cisternae

Form large, perpendicular cross

channels at the A band-I band junctions

T-tubules

Elongated tubes located at each A

band-I band junction, formed by the

sarcolemma penetrating into the cell

interior

Lumen

is continuous with the

extracellular space

● Conduct impulses to the deepest

regions of the muscle cell and to every

sarcomere

terminal cisterna + T tubule +

sarcoplasmic ret

Triad

Synaptic clef

Space that separates the axon

terminal and the muscle fiber

○ Filled with gel-like extracellular

substance rich in glycoproteins

and collagen fibers

Acetylcholine

Neurotransmitter released from The presynaptic vesicles

Acetylcholinesterase

Enzyme located in the synaptic

cleft which breaks down Ach

Motor end plate

Trough-like part of the muscle

fiber's sarcolemma

○ Highly-excitable region,

responsible for initiation of action

potentials across the muscle's

surface

Cardiac myocytes

separate cellular

unit of cardiac muscle

80 micrometers L, 15 micrometers diameter

Size of cardiac myocytes

Intercalated disks

Joined end to end

at junctional complexes, which is

comparable to zonula adherens of

Cardiac muscle

Principal identifying features of cardiac

muscle are:

1. Centrally placed single nucleus of the

myocytes

2. Presence of transverse intercalated

disks at intervals along the length of the

myofibers

influx of calcium

Smooth muscle contraction is

initiated by

calmodulin

Influx of calcium that binds

to calcium binding protein

calcium-calmodulin complex

binds to myosin light chain-kinase that

activates and catalyzes the

phosphorylation of myosin light chains,

enabling to interact with actin filaments

and cause contraction

Intracellular Ca+

(stores Ca+ and releases it on demand when

the muscle fiber is stimulated to

contract)