Histology Lecture Notes PDF

Connective Tissue Connective tissue: is a tissue bind structures together, form a framework and support for organs and the body as a whole, store fat, transport substances, protect against disease, and help repair tissue damage. Characteristics of C.T: 1) It presents throughout the body....

Connective Tissue Connective tissue: is a tissue bind structures together, form a framework and support for organs and the body as a whole, store fat, transport substances, protect against disease, and help repair tissue damage. Characteristics of C.T: 1) It presents throughout the body. 2) Characterized by an abundance of intercellular matrix with few cells. 3) Able to reproduce but not as rapidly as epithelial cells. 4) Most connective tissues have a good blood supply but some do not. 5) Originate from the middle germ layer ( mesoderm). 6) Cells do not rest on a basement membrane. Classification OF C.T:  C.T is classified according to the type of ground substance into : I. C.T Proper II. Skeletal C.T III. Vascular C.T Select this paragraph to edit I. Connective tissue proper Types of C.T proper: 1. Areolar connective tissue. 2. Fibrous connective tissue. 3. Elastic connective tissue. 4. Reticular connective tissue. 5. Mucous connective tissue. 6. Adipose connective tissue.  Select this paragraph to edit Name (Type) Found in 1- Areolar connective tissue: 1. In the skin as well as in places that connect epithelium to other tissues. 2. In the eye ball. 3. Beneath the dermis layer 4. underneath the epithelial tissue. 5. It is also a component of mucus membranes found in digestive, respiratory, reproductive, and urinary systems. 6. surrounds blood vessels and nerves. 2. Fibrous connective tissue (FCT): Tissues form ligaments and tendons 3. Elastic connective tissue : Lung and ligaments which bind articulating bones together. 4. Reticular connective tissue : support the lymphoid organs (lymph nodes, red bone marrow, thymus, and spleen). 5. Mucous connective tissue : Found in: the umbilical cord during fetal development. 6. Adipose connective tissue : Found in: In subcutaneous layer below skin. Select this paragraph to edit II. Skeletal Connective tissue  Skeletal connective tissue : Is a type of connective tissue forms the internal skeleton which supports the body and to which the muscles are attached.  The internal skeletal system consists of : Rigid (bone) or semi-rigid (cartilage) structures, Bone: rigid, mineralized and ossified structures, connected by ligaments and connected to the muscular system via tendons. Cartilage: semi-rigid, not ossified structures, supporting the human ear and nose. Note: sharks composed entirely of cartilage and without any calcified bones at all. Select this paragraph to edit A- Cartilage  Cartilage is type of dense connective tissue, composed of collagen fibers and/or elastin fibers + cartilage cells (chondrocytes).  Found in: joints, rib cage, ear, nose, and bronchial tubes.  There are three main types of cartilage : 1. Elastic 2. Hyaline 3. Fibrocartilage. 1- Hyaline cartilage :  Has fibers scattered throughout its matrix, which looks glassy.  It has a clear ground substance, Chondrocytes are found in lacunae.  Function: it is required in the endochondral development of bone.  Found in: Trachea. 2- Elastic cartilage :  Similar to hyaline cartilage but contains elastic fibers (elastin) scattered throughout the matrix.  Found in: pinna of the ear and several tubes, such as auditory (Eustachian) tubes and larynx and especially in the epiglottis.  Function: present to keep these tubes permanently open.  Select this paragraph to edit 3- Fibrocartilage :  Fibrocartilage is very fibrous.  Found in: between the vertebrae of the spinal column.  Calcified cartilage :  Calcium salts are deposited.  Found in: xiphisternum of toad. Select this paragraph to edit B- BONE Select this paragraph to edit  Bones are rigid connective organs that make up the skeleton of vertebrates.  Bones are primarily comprised of osseous tissue also called bone tissue, that gives it rigidity.  Bones have eight main functions : 1. Protection : Bones can serve to protect internal organs, such as: the skull protecting the brain the ribs protecting the heart and lungs. 2. Shape : Bones provide a frame to keep the body supported. 3. Blood production : The marrow, located within the medullary cavity of long bones and the interstices of cancellous bone, produces blood cells in a process called haematopoiesis. 1. Mineral storage : Bones act as reserves of minerals important for the body, mostly calcium and phosphorus. 2. Movement: Bones, skeletal muscles, tendons, ligaments and joints function together to generate and transfer forces so that individual body parts or the whole body can be moved in three-dimensional space. 3. Acid-base balance: Bone buffer the blood against excessive pH changes by absorbing or releasing alkaline salts. 1. Detoxification: Bone tissues can also store heavy metals metals and foreign elements, removing them from the blood and reducing their effects on other tissues. These can later be released for excretion. 8. Sound transduction: Bones are important in the mechanical aspect of hearing. Types of bones: 1- Compact bone. 2- Trabecular (Spongy) bone. 1- Compact bone:  The hard outer layer of bones is composed of compact bone tissue, so-called due to its minimal gaps and spaces.  This tissue gives bones their smooth, white, and solid appearance.  Compact bone accounts for 80% of the total bone mass of an adult skeleton. Compact bone may also be referred to as dense bone or cortical bone. 2- Trabecular (Spongy) bone:  Filling the interior of the organ, the trabecular bone tissue (an open cell porous network also called cancellous or spongy bone).  Spongy bone is comprised of a network of rod- and plate- like elements that make the overall organ lighter and allowing room for blood vessels and marrow.  Trabecular bone accounts for the remaining 20% of total bone mass, but has nearly ten times the surface area of compact bone. Select this paragraph to edit  Three types of cavities exsit in bone: Haversian canals, marrow cavities, and the lacuna. Which contain the bone cells (osteocytes) from which canalicuae (small tunnels) extend.  thisVascular SelectIII. paragraph to edit (fluid) Connective tissue Blood Select this paragraph to edit 1- BLOOB  Blood is a connective tissue its origin from the bones.  The ground substance is a fluid known as plasma.  Blood is a circulating tissue consisting of several types of cells suspended in a fluid medium known as plasma.  The cellular constituents are : 1. Red blood cells (Erythrocytes), carry respiratory gases and give it its red color. 2. White blood cells (leukocytes), which fight disease. 3. Platelets (Thrombocytes), cell fragments which play an important role in the clotting of blood. Functions of blood : 1) Supply of oxygen to tissues (bound to hemoglobin which is carried in red cells). 2) Supply of nutrients such as glucose, amino acids and fatty acids (dissolved in the blood or bound to plasma proteins). 3) Removal of waste such as carbon dioxide, urea and lactic acid. 4) Immunological functions, including circulation of white cells, and detection of foreign material by antibodies. 5) Coagulation, which is one part of the body's self- repair mechanism. Select this paragraph to edit 1) Messenger functions, including the transport of hormones and the signaling of tissue damage. 2) Regulating of body pH. 3) Regulating of core body temperature. Structure of blood : A. Cellular components (45%): 2. Erythrocytes (R.B.Cs) 3. Leukocytes (W.B.Cs) 4. Thrombocytes (platelets) B. Plasma (55%). A- Cellular components (45%): 1- Erythrocytes (R.B.Cs) :  Its mean number is: 4.7 - 6.1 million (in male), 4.2 - 5.4 million (in female).  In mammals, mature red blood cells lack nucleus.  They contain the blood's hemoglobin.  The proportion of blood occupied by red blood cells is called the hematocrit. Select this paragraph to edit 2- Leukocytes (W.B.Cs) :  Its mean number is: 4.000 – 11.000 (in both male & female).  White blood cells are part of the immune system; they destroy and remove old or aberrant cells and cellular debris, as well as attack infectious agents (pathogens) and foreign substances. Select this paragraph to edit 3- Thrombocytes (platelets) : 1. Its mean number is: 200,000 – 500,000. 2. Platelets are responsible for blood clotting (coagulating). 3. They change fibrinogen into fibrin. This fibrin creates a mesh onto which red blood cells collect and clot. 4. Functions of clot: stops more blood from leaving the body (stop bleeding). helps to prevent bacteria from entering the body. B. Plasma (55%): (2.7 – 3.0 litres in human)  Blood plasma, is a fluid that is the blood's liquid medium, appearing golden-yellow in color.  Blood plasma is an aqueous solution containing : 1. 92% water. 2. 8% blood plasma proteins, and trace amounts of other materials: (Serum albumin - Blood clotting factors - Immunoglobulins (antibodies) - Hormones - Carbon dioxide - Various other proteins - Various electrolytes- Blood lipids).  Note: Serum → is plasma from which the clotting proteins have been removed, most remaining proteins are albumin and immunoglobulins. Select this paragraph to edit 2- LYMPH Select this paragraph to edit  The lymphatic system is a complex network of lymphoid organs, lumph nodes, lymph ducts, lymphatic tissues, lymph capillaries and lymph vessels that produce and transport lymph fluid from tissues to circulatory system.  The lymphatic system is a major component of the immune system.  Function : 1. Removal of excess fluids from body tissues. 2. Absorption of fatty acids and transport of fat to the circulatory system. 3. Production of immune cells such as lymphocytes and monocytes.