Tissue combinations from muscle, fat and bone which are the gross components of carcasses, and their properties and proportions are responsible for quality and leanness of meat.

Skeletal muscles constitute 35-65 % of carcass weight of meat animals.
Smooth muscle - blood vessels
Cardiac muscle- is confined solely to the heart

Are organs of the muscular system
There are more than 600 muscle in the animal body.
Vary widely in shape, size and action.
The structure of muscle will be showed in Figure

Is the highly specialized cell.
Constitute 75-92% of muscle volume
Blood vessels, nerve fibers and extracellular fluid make up the other volume.

Are long , unbranched, threadlike cells which taper slightly at both ends.
Vary considerably in diameter.
Ranged from 10um->100 um within the same species or the same muscle.(micrometer=one millionth of a meter)

Surround the muscle fiber
Is composed of protein and lipid material and it relatively elastic (adjust very well during contraction, relaxation and stretching).
A network of tubules called transverse tubules – T system or T tubules is circumferential on the surface.

Are long , thin, cylindrical rods, usually
1-2 um in diameter.
A muscle fibers of meat animals with diameters of 50um have at least 1000 and could have as many as 2000 or more myofibrils.

In myofibrillar cross-section, a well ordered array of dots that have two distinct size. ( thin and thick filaments).
Area of different density are visible within light and dark bands of myofibrils.
The unit of the myofibril between two adjacent Z disks- a sarcomere

includes both an A band and the two half T bands located on either side of the A band.
Is the repeating structural unit of the myofibril.
Is also the basic unit in which events of the muscle ’ s contraction-relaxation cycle occur.

Divided into thick and thin filaments.
Thick filaments – 14-16 nm
( nanometer, one-billionth of a meter) in diameter and 1.5 um long, constitute the
A band of the sarcomere ; referred as myosin filament. Some of which are located in the M line .

Thin filaments : are about 6-8 nm in diameter , 1.0 um long; on either side of the Z disk; they also constitute the I band and extend beyond the I band into the A band, referred as actin filaments

H zone : Only thick filaments (myosin) are present.
A band : thin and thick filaments overlap , show six thin filaments surrounding each thick filament
I band : only thin filaments (actin)are present.

The protein actin and myosin :65% of the protein of the myofibril.
The remaining fraction consists of regulatory (tropomyosin and troponin) and cyto-skeletal proteins ( c-protein- encircle the myosin filament , desmin- encircle the Z disks).

20% of the myofibrillar protein
A globular shaped molecule , 5.5 nm in diameter.Referred to as G-actin
F actin is linked by G-actin
The actin filament : two strands of F- actin are spirally coiled around one another to form a super helix

Is a fibrous protein.
45% of myofibrillar protein.
Is an elongated rod shape, with a thickened portion at one end- referred to as the head region. Another is the long thin portion – is called the rod or tail portion, between two is called the neck.

Sarcoplasmic Reticulum and T tubules
Sarcoplasmic Reticulum (SR)- is a membraneous system of tubules and cisternae (reservoirs for Ca+2). Longitudinal tubules and terminal cisternae
Transverse tubules – T system or T tubules is circumferential on the surface.
Usually discussed together, are two separate and distinct membrane systems.

Connects and holds verious parts of the body together.
Are distributed throughout the body.
Such as blood vessel , tendon, nerve trunk. Or skin , hide
Fat storage cells are located within a specialized type of connective tissue – adipose tissue.

Ground substance – containing soluble glycoprotein(carbohydrate +protein), such as proteoglycans or glycosaminoglycans (hyaluronic acid – can be found in joints and chondroitin sulfates- can be found in cartilage, tendons and adult bone)

Extracellular fibers: reticulin, collagen and elastin.
Collagen is the most abundant protein in the animal body and significantly influences meat tenderness. Constitutes
20-25% of total body protein; is a glycoprotein.

Glycine is the most abundant amino acid in collagen and comprises about
1/3 of the total amino acids.
Hydroxyproline, and proline account for another 1/3 of its amino acid content.
Hydroxyproline is a relatively constant component of collagen (13-14 %).

In young animal , cross linkages are fewer in number and more easily broken.
Collagen is more soluble in young animals and becomes less soluble as the animal ages.

Is a much less abundant connective tissue protein than collagen.
Is a rather rubbery protein that is present throughout the body in ligaments and arterial walls
Is highly resistant to digestive enzymes and no method of cookery has any appreciable solubilizing effect on it.

Is composed of small fibers that form delicate networks around cells, blood vessels, neural structures which hold them in place.
Are numerically overwhelmed by collagenous fibers.

Accumulation of numerous adipocytes.
Also know as fat.
Contains two types of adipose tissue ; white and brown fat. White type is the most in meat animal . Brown type is present in all of them at birth, especially around the kidneys.

Muscle are usually classified as red, or white, based principally on their color intensity, which is attributable to the proportion of red and white fibers they contain.
Few muscle are composed of all red or white fibers.
Most are mixtures of red and white fibers
For example, red muscle are those with higher proportion of red fibers than found in white muscle.

Such as leg muscle and breast muscle of chicken or turkey.
Different color also can be showed in various parts in a meat animal.
The structural, functional and metabolic characteristics of red , intermediate and white muscle fibers are different.

Moisture :65-80%
Protein:16-22%
Lipid: 1.5-13%
Carbohydrates: 0.5-1.5%
Mineral: 1.0-1.2%