أنواع الأنسجة الأربعة

Four Types of Tissue

• Epithelial = طلائي
• Connective = رابط
• Muscle (Muscular) = عضلي
• Nervous = عصبي

Few notes on transitional epithelial tissue

• It is a stratified epithelium consisting of multiple layers of cells.
• The shape of the cell changes according to the function of the organ.
• The layers of cells may look cubical or round when in a relaxed state, except the apical layer which seems to be flattened when stretched.
• The main site for this epithelium is the urinary bladder ("urothelium").
• The cells are arranged into three groups:
  • Basal layer (rich in protein and mitochondria) attached to a basement membrane
  • Intermediate layer: high rate of proliferation (multiplication) and rich in Golgi apparatus
  • Apical layer (the superficial layer), lines the lumen, and protects the underlying layer of cells against harmful waste material and pathogens from the lumen.

Functions of Transitional Epithelial Tissue

• Permeability barrier
• Control of volume of the organ

Epithelial Tissue

• A human body is composed of four basic tissue types:
  • Epithelial
  • Connective
  • Muscular
  • Nervous tissues.
• Each tissue consists of similarly specialized cells united in performing a specific function.
• The basic tissues contain extracellular matrix (ECM) and cells.
• The proportion of ECM and cells is variable in different organs.

Main Characteristics of Four Basic Tissue Types

General Organ Structure

• In general, each organ in the body is divided into:
  • The parenchyma (لحمة نسيج حشوي), which is composed of the cells responsible for the organ's specialized functions.
  • The stroma (نسيج ساند أو سدى), the cells which have a supporting role in the organ.

Epithelial Tissue (Detailed)

• Epithelial tissues are composed of closely aggregated polyhedral cells adhering strongly to one another and to a thin layer of ECM.
• They form cellular sheets that line the cavities of organs and cover the body surface.
• All substances that enter or leave an organ must cross this type of tissue.
• The principal functions of epithelial tissues:
  • Covering, lining, and protecting surfaces (e.g., skin)
  • Absorption (e.g., the intestinal lining)
  • Secretion (e.g., glands)
• Classification according to cell shape and layers:
  • Three principal cell shapes associated with epithelial cells:
    • Squamous epithelium: Flattened and scale-like
    • Cuboidal epithelium: Like a cube
    • Columnar epithelium: Having the shape of a column.
  • Three descriptions of layers:
    • Simple: one layer
    • Stratified (multilayers)
    • Pseudostratified
• Also there are keratinized epithelial cells in skin and transitional epithelial cells in the Urinary bladder

Different Types of Epithelial Tissue

• Provides diagrams and examples of various types (simple squamous, simple cuboidal, simple columnar with microvilli, stratified squamous, transitional, pseudostratified columnar with cilia and microvilli)

Specific Tissue Types (Microscopic Images)

• Provides microscopic images of different tissues (stratified squamous tissue, stratified cuboidal epithelial tissue).

Connective Tissue

• Connective tissue is the most abundant and widely distributed of the primary tissues.
• Connective tissue is divided into four main categories:
  • Connective tissue proper (Cells, Fibers and ground substance)
  • Cartilage (specialized CT)
  • Bone (specialized CT)
  • Blood (specialized CT)

Structure of Connective Tissue

• Connective tissue proper has three main components:
  • Cells
  • Fibers
  • Ground substances
• Together the ground substance and fibers make up the extracellular matrix.
• The cells are of two types:
  • Fixed cells (fibroblasts, fat cells)
  • Wandering cells (macrophages, plasma cells, mast cells and lymphocytes)
• Three classes of components
  • Cells
  • Fibers (reticular, elastic, collagenous)
  • Ground substance (macromolecules, multiadhesive glycoproteins)

Functions of Connective Tissue

• Supporting and moving (ligaments and tendons)
• Protecting organs (cranium and blood)
• Insulating
• Storing reserve fuel (Adipose tissue and bones)
• Transporting substances within the body (blood)

Types of Connective Tissue Proper

• Loose connective tissue (Areolar, Adipose, Reticular)
• Dense connective tissue (Regular, Irregular, Elastic)

Blood

• Blood is a specialized connective tissue consisting of cells (erythrocytes, leukocytes, platelets) and fluid called plasma.
• The bone marrow produces all blood cells.
• The blood circulates in the vascular system of a human.
• Physical Characteristics of Blood:
  • Thicker than water
  • 8% of total body weight
  • In males 5-6 liters, in females 4-5 liters.
  • Normally has a pH of about 7.4
• Components of Blood:
  • Blood cells (45%)
  • Plasma (55%)
• Functions of Blood:
  • Supply of nutrient to cells
  • Transportation of O2 & CO2 in the body
  • Protects from infection
  • Removing waste material (e.g., urea, CO2)
  • Clotting
  • Regulation of body temperature

Blood Components - Detailed

• Red Blood Cells (Erythrocytes):
  • Biconcave shape
  • Elastic cell membrane
  • No nucleus
  • 95% of RBC consist of hemoglobin (red pigment).
  • Formed in red bone marrow
  • Average life is 4 months
  • The main function is to transport O2 & CO2.
• White Blood Cells (Leukocytes):
  • Much larger than red blood cells
  • Formed in the bone marrow
  • Only 2% of total WBC population circulating in blood at a time (rest in the skin, lungs, and spleen)
• Platelets (Thrombocytes):
  • Also called thrombocytes
  • Platelets are not cells, they are fragments of large cells.
  • Nucleus is absent
  • Random shaped
  • 2-4 micron size
  • Normal platelet count is 150,000-400,000 per microliter of blood.
  • Platelets have a lifespan of only 5 to 9 days
  • Platelets are formed in the bone marrow
  • Function: Formation of blood clots and stops bleeding.
• Plasma:
  • Plasma: 92% water, it contains:
    • Glucose
    • Hormones
    • Proteins
    • Mineral salts
    • Fats
    • Vitamins
  • Functions:
    • Plasma helps maintain blood pressure
    • Regulates body temperature
    • It contains minerals, salts, hormones and proteins that perform important functions in the body
    • PH buffering

Detailed Types of White Blood Cells (WBCs)

• Granulocytes: (Neutrophils, Eosinophils, Basophils)
• Agranulocytes: (Monocytes, Lymphocytes)
  • Provides detailed descriptions of each type (structure, function, numbers).

Peripheral Blood Smear - Diagrams

• Shows diagrams of peripheral blood smears highlighting different blood components and their characteristics.

هذا الاختبار يغطي الأنواع الأربعة من الأنسجة، بما في ذلك الأنسجة الطلائية، الرابطة، العضلية، والعصبية. كما يتضمن معلومات عن الأنسجة الطلائية الانتقالية ووظائفها الرئيسية في الجسم، خصوصًا في المثانة البولية. اختبار مثالي للطلاب الذين يدرسون علم الأحياء.