Animal TissuesAnimal Tissues أنسجة الحيوانأنسجة الحيوان (Histology(Histologyعلم األنسجةعلم األنسجة ))

Animals are multicellular organismsAnimals are multicellular organismsكائنات عديدة الخالياكائنات عديدة الخاليا with their specialized cells grouped into with their specialized cells grouped into tissuestissues..

In most animals, combinations of various In most animals, combinations of various tissues make up functional units called tissues make up functional units called organsorgans, , and groups of organs that work together form and groups of organs that work together form systemssystems..

For example, the human digestive system consists of a For example, the human digestive system consists of a stomach, small intestine, large intestine, and several stomach, small intestine, large intestine, and several other organs, each a composite of different tissues.other organs, each a composite of different tissues.

Lecture 11: Lecture 11: Animal TissuesAnimal Tissues

Animal Tissues Animal Tissues أنسجة الحيوانأنسجة الحيوان (Histology)(Histology)

Organs in animals are Organs in animals are composed of a number composed of a number of different of different tissue tissue typestypes..

Organs are composed Organs are composed of of tissuestissues, which are in , which are in turn composed of turn composed of cellscells

Organization of the Animal Body Organization of the Animal Body

Animal Tissues (Histology)Animal Tissues (Histology)A tissueA tissue is a group of cells with a common is a group of cells with a common

structure and function.structure and function.

Different types of tissues have different structures Different types of tissues have different structures that are especially suited to their functions.that are especially suited to their functions.

A tissue may be held by a sticky extra-cellular A tissue may be held by a sticky extra-cellular matrix that coats the cells or weaves them matrix that coats the cells or weaves them together in a fabric of fibers.together in a fabric of fibers.

Types of tissues:Types of tissues: 1- Epithelial tissue 1- Epithelial tissue نسيج طالئينسيج طالئي,,

2- Connective tissue 2- Connective tissue نسيج ضامنسيج ضام, ,

3- Nervous tissue 3- Nervous tissue نسيج عصبينسيج عصبي, ,

4- Muscle tissue 4- Muscle tissue نسيج عضلينسيج عضلي..

(1) Epithelial Tissues (1) Epithelial Tissues األنسجة الطالئية

CoversCovers تغطي body surfaces and body surfaces and lineslines تبطنتبطن body cavitiesbody cavities

Function of EpitheliumFunction of Epithelium

Lining organsLining organs

األعضاء األعضاء تبطين تبطين

Protecting organsProtecting organs

األعضاء األعضاء حماية حماية

Forming glandsForming glands

الغدد الغدد تكوين تكوين

Glands can be single epithelial cells, such as the Glands can be single epithelial cells, such as the goblet cells goblet cells الكأسية الكأسية الخاليا .that line the intestine. that line the intestineالخاليا

Multicellular glands Multicellular glands الخاليا عديدة الخاليا الغدد عديدة include the include theالغددendocrine glands الصماء الصماء الغدد . . الغدد

Epithelia are classified by the Epithelia are classified by the number of cell layersnumber of cell layers and the and the shape of cellsshape of cells on the free surface. on the free surface.

Types of epitheliaTypes of epithelia

SSimple epithelium imple epithelium بسيطبسيط:: is a single layer of cells, is a single layer of cells,

Stratified epithelium Stratified epithelium طبقييطبقيي:: is multiple layers of cells.is multiple layers of cells.

PseudostratifiedPseudostratified epithelium: epithelium: طبقيطبقي كاذب is a single layer of cells is a single layer of cells but appear to form two layers. but appear to form two layers.

Types of epithelial cells:Types of epithelial cells: - - CuboidalCuboidal ( (مكعبةمكعبة), ),

- Columnar- Columnar ( (عموديةعمودية), ),

- Squamous- Squamous ( (حرشفيةحرشفية).).

طبقية طبقية حرشفية حرشفية

حرشفية حرشفية بسيطةبسيطة

بسيطة بسيطة عمودية عمودية

بسيطة بسيطة مكعبة مكعبة

طبقية طبقية عمودية عمودية

مهدبة مهدبة عمودية عموديةكاذبة كاذبة طبقية طبقية

2.2. Muscle tissue Muscle tissue النسيج العضليالنسيج العضلي:: Is composed of long cells called Is composed of long cells called muscle fibersmuscle fibers ألياف ألياف

that are capable of contracting when stimulated that are capable of contracting when stimulated عضليةعضليةby nerve impulses.by nerve impulses.

It has large numbers of It has large numbers of myofibrilsmyofibrils 7يفات عضلية 8ي 7يفات عضليةل 8ي made of the made of the لcontractile proteins contractile proteins actinactin األكتيناألكتين and and myosinmyosinالميوسينالميوسين ..

Muscle is the most abundant tissue in most animals, Muscle is the most abundant tissue in most animals,

There are three types of muscle tissue There are three types of muscle tissue in the vertebrate body:in the vertebrate body:

a)a) Skeletal muscleSkeletal muscle,, الهيكلية الهيكلية العضالت العضالت

b)b) Cardiac muscleCardiac muscle, , القلبية القلبية العضالت العضالت

c)c) Smooth muscleSmooth muscle الملساء الملساء العضالت .. العضالت

a)a) Skeletal muscleSkeletal muscle:: - It attaches to bones by tendons األوتار, skeletal

muscle is responsible for voluntary movements الحركات.اإلرادية

- Also called striated muscle عضالت مخططة.

b)b) Cardiac muscleCardiac muscle:: - forms the contractile wall

of the heart. - Cardiac cells are branched.

a)a) Smooth muscle:Smooth muscle: b) No striations, c) Is found in the walls of the digestive tract,

urinary bladder, arteries, and other internal organs.

d) Its cells are spindle-shaped.