Lecture 12 Animal Tissues 3 Connective Tissues Connective
- Slides: 12
Lecture 12: Animal Tissues (3) Connective Tissues ﺍﻷﻨﺴﺠﺔ ﺍﻟﻀﺎﻣﺔ • Connective tissue functions: - They mainly to bind ﺗﺮﺑﻂ and support ﺗﺪﻋﻢ other tissues. • Structure: – Connective tissues have a population of cells scattered ﻣﺒﻌﺜﺮﺓ through an extracellular matrix ﺍﻟﻮﺳﻂ ﺑﻴﻦ ﺍﻟﺨﻠﻮﻱ. – The matrix generally consists of fibers ﺃﻠﻴﺎﻑ that may be liquid, jellylike, or solid. – In most cases, the connective tissue cells secrete the matrix. – The matrix may be solid (as in bone), soft (as in loose connective tissue), or liquid (as in blood).
Types of connective tissues fibers There are three kinds of connective tissues fibers, which are all proteins: a)- Collagenous fibers (white) ﺍﻷﻠﻴﺎﻑ ﺍﻟﻜﻮﻟﻼﺟﻴﻦ : Are made of collagen and non-elastic ﻏﻴﺮ ﻣﺮﻧﺔ b)- Elastic fibers (Yellow) ﺍﻟﻤﺮﻧﺔ ﺍﻷﻠﻴﺎﻑ : Are long threads ﺧﻴﻮﻁ of elastin, which provide ﺗﻮﻓﺮ a rubbery quality ﺟﻮﺩﺓ ﻣﻄﺎﻃﻴﺔ. c)- Reticular fibers ﺍﻷﻠﻴﺎﻑ ﺍﻟﺸﺒﻜﻴﺔ : Are very thin and branched, and composed of collagen. It joins ﻳﺮﺑﻂ connective tissues to adjacent tissues ﺍﻷﻨﺴﺠﺔ ﺍﻟﻤﺠﺎﻭﺭﺓ.
Types of connective tissues The major types of connective tissues in vertebrates are: A)- Loose connective tissue ﺍﻟﻤﻔﻜﻜﺔ , B)- Adipose connective tissue ﺍﻟﺪﻫﻨﻴﺔ , C)- Fibrous connective tissue ﺍﻟﻠﻴﻔﻴﺔ , D)- Cartilage ﺍﻟﻐﻀﺮﻭﻑ , E)- Bone ﺍﻟﻌﻈﻢ , F)- Blood ﺍﻟﺪﻡ. ﺃﻨﺴﺠﺔ ﺿﺎﻣﺔ ﺃﺼﻴﻠﺔ ﺃﻨﺴﺠﺔ ﻫﻴﻜﻠﻴﺔ ﺃﻨﺴﺠﺔ ﻭﻋﺎﺋﻴﺔ Each has a structure correlated with its specialized function.
A. Loose connective tissue ﺍﻟﻨﺴﻴﺞ ﺍﻟﻀﺎﻡ ﺍﻟﻤﻔﻜﻚ : - Binds epithelia to underlying tissues and functions a holding organs in place. - It has all three fiber types. - It composes of two cell types: 1. Fibroblasts ﺧﻼﻳﺎ ﻟﻴﻔﻴﺔ : secrete the protein ingredients of the extracellular fibers. 2. Macrophages ﺧﻼﻳﺎ ﺑﻠﻌﻤﻴﺔ : are amoeboid cells that engulfing ﺗﺒﺘﻠﻊ bacteria and the debris of dead cells by phagocytosis. A
B. Adipose tissue ﺍﻟﻨﺴﻴﺞ ﺍﻟﺪﻫﻨﻲ : It is a specialized form of loose connective tissues that store fat in adipose cells ﺧﻼﻳﺎ ﺩﻫﻨﻴﺔ distributed throughout the matrix. B Functions: • Adipose tissue stores fuel as fat molecules. • Each adipose cell contains a large fat droplet that swells when fat is stored and shrinks when the body uses fat as fuel.
C. Fibrous connective tissue ﺍﻟﻨﺴﻴﺞ ﺍﻟﻀﺎﻡ ﺍﻟﻠﻴﻔﻲ : - It is dense, due to its large number of collagenous fibers. - The fibers are organized into parallel bundles ﺣﺰﻡ making it strong. Functions: This type of connective tissue attaching muscles to bones, and joining bones to bones at joints ﻓﻲ ﺍﻟﻤﻔﺎﺻﻞ. C
D. Cartilage ( ﺍﻟﻐﻀﺮﻭﻑ Skeletal Tissue): It has an abundance of collagenous fibers embedded in ﺟﺰﺀ ﻻ ﻳﺘﺠﺰﺃ ﻣﻦ a rubbery matrix Chondrocytes ﺍﻟﺨﻼﻳﺎ ﺍﻟﻐﻀﺮﻭﻓﻴﺔ : helps making cartilage flexible support material. We have cartilage in nose, ears, and vertebral disks. D
E. Bone ( ﺍﻟﻌﻈﻢ Skeletal Tissue): The skeleton supporting most vertebrates is made of bone, a mineralized connective tissue. This bone contains osteoblasts ﺍﻟﺨﻼﻳﺎ ﺍﻟﻌﻈﻤﻴﺔ that deposit ﺗﺮﺳﺐ a matrix of collagen. • Bone is harder than cartilage. • Hard mammalian bones consists of repeating units called osteons ﻣﺤﺎﻓﻆ ﻋﻈﻤﻴﺔ (Haversian system). • Each osteon has a central canal containing blood vessels and nerves that service the bone. 5
F. Blood ( ﺍﻟﺪﻡ Vascular Tissue): Functions differently from other connective tissues, but it does have an extensive extra-cellular matrix. The matrix is a liquid called plasma, consisting of water, salts, and a variety of dissolved proteins. Types of blood cells are: 1. Erythrocytes (red blood 2. 3. cells), Leukocytes (white blood cells) Platelets. Functions of cells: • • • Red cells carry oxygen. White cells function in defense against microbes. Platelets help in blood clotting. 6
4. Nervous tissue: Senses stimuli and transmits signals from one part of the animal to another. The functional unit of nervous tissue is the neuron, or nerve cell. It consists of a cell body and two or more extensions ﻣﻠﺤﻘﺎﺕ , called dendrites ﺗﻔﺮﻋﺎﺕ ﺷﺠﻴﺮﻳﻪ and axons ﻣﺤﺎﻭﺭ.
• Dendrites transmit nerve impulses from their tips toward the rest of the neuron. • Axons transmit impulses toward another neuron or toward an effector, such as a muscle cell.