Lecture Notes in Medical Histology 'Abridged' PDF

3. Muscle tissues/cells 4. Nervous tissues/cells In this year, details of these tissues is the main subject of Histology Epithelial = ‫طالئي‬ Connective = ‫رابط‬ Muscle (Muscular) =‫عضلي‬ Nervous =‫عصبي‬ 5 The structure of a living cell Few notes on transitio...

3. Muscle tissues/cells 4. Nervous tissues/cells In this year, details of these tissues is the main subject of Histology Epithelial = ‫طالئي‬ Connective = ‫رابط‬ Muscle (Muscular) =‫عضلي‬ Nervous =‫عصبي‬ 5 The structure of a living cell 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 calls are arranged into Three groups: 1. Basal layer (rich in protein and mitochondria) attached to a basement membrane 2. Intermediate layer : high rate of proliferation (multiplication) and rich in Golgi apparatus 3. Apical layer (the superficial layer), lines the lumen, and protects the 6 underlying layer of cells against harmful waste material and pathogens from the lumen Functions of the transitional epithelial tissue 1. Permeability barrier 2. Control of volume of the organ Lecture Two: Epithelial tissue Jenan Y Taha (MB,ChB, FIBS/Haematlogy) Samira TS Al-Ali (MSc anatomy and histology Reference: th Junqueira’s Basic Histology: Text and Atlas 14 edition A human body is composed of four basic tissue types: Epithelial Connective Muscular Nervous tissues. A. Each tissue consists from similarly specialized cells united in performing a specific function. B. The basic tissues contains extracellular matrix (ECM) and cells C. The proportion of ECM and cells is variable in different organs. 7  Very important table In general, each organ in the body is divided into a. The parenchyma ( ‫نسيج حشوي‬/‫)لحمة‬, which is composed of the cells responsible for the organ’s specialized functions, and b. The stroma ( ‫)نسيج ساند أو سدى‬, the cells which have a supporting role in the organ. 8 - 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: 1. Covering, lining, and protecting surfaces (eg, skin ) 2. Absorption (eg, the intestinal lining) very important 3. Secretion (eg, glands) Classification according to cell shape and layers There are three principal cell shapes associated with epithelial cells: squamous epithelium: Flattened and scale-like cuboidal epithelium: Like a cube and columnar epithelium: Having the shape of a column. There are three descriptions of layers: Simple: one layer very important Stratified(multilayers) Pseudostratified Also there are keratinized epithelial cells in skin And transitional epithelial cells in Urinary bladder 9 10  very important Different types of epithelial tissue 11 Stratified squamous tissue 12 Stratified cuboidal epithelial tissue 13  Lecture Three: Connective tissue This slide shows the complexity of the connective tissue Connective tissue is the most abundant and widely distributed of the primary tissues Connective tissue (CT)is divided into four main categories: 1. Connective tissue proper (Cells, Fibers and ground substance) 2. Cartilage –specialized CT 3. Bone – specialized CT very important 4. Blood – Specialized CT 14 Connective tissue proper has three main components: Cells Fibers Ground substances Together the ground substance and fibers make up the extracellular matrix. very important The cells are of two groups: Fixed cells – fibroblasts, fat cells. Wandering cells – macrophages, plasma cells, mast cells and lymphocytes 15 Functions of connective tissue Supporting and moving Protecting organs (cranium and blood) very important Insulating and Storing reserve fuel (Adipose tissue and bones) Transporting substances within the body (blood). Connecting tissues to one another (ligaments and tendons) Fibers in connective tissues 1) Collagen fibers: are large fibrous proteins and are secreted into the extracellular space and they provide high tensile strength to the matrix very important 2) Elastic Fibers: are long, thin fibers that form branching network in the extracellular matrix. They help the connective tissue to stretch and recoil. 3) Reticular Fibers: are short, fine collagenous fibers that can branch extensively to form a delicate network. (support) 16 Connective tissue proper has two subclasses; Loose and Dense Loose connective tissue is divided into: 1) Areolar 2) Adipose 3) Reticular Dense connective tissue is divided into 1) Dense regular 2) Dense irregular 3) Dense elastic Loose connective tissue is distributed through the body as binding &packing material The protein fiber are loosely arranged. Contain fewer cells &fiber than the dense connective tissue but has more ground substance Occupy the space between organs. 17 Areolar connective tissue These tissues are widely distributed and serve as a universal packing material between other tissues. The functions of areolar connective tissue support binding of other tissues. Strength Areolar Connective Tissue 18 Reticular connective tissue This tissue resembles areolar connective tissue, but the only fibers in its matrix are the reticular fibers, which form a delicate network. The reticular tissue is limited to certain sites in the body e.g lymph nodes, spleen and the bone marrow. Adipose tissue or body fat This is loose connective tissue composed of adipocytes. It is composed of 80% Fat. It a store of energy in the form of lipids and reduce heat loss in skin. 19 The two types of adipose tissue : white adipose tissue , present in adults &has less blood supply. brown adipose tissue, present in infant &has extensive blood supply. Dense connective tissue : Consists of density packed fibers with little space between fibers. Dense regular connective tissue This consists of closely packed bundles of collagen, fibers running in the same direction. These collagen fibers are slightly wavy ,resist stretching & give strength. This tissue found in tendon (connect muscle to bone ) & ligaments (connect bone to bone ) Dense Irregular tissue This has the same structural elements as dense regular tissue, but the bundles of collagen Fibers are much thicker and arranged irregularly. This tissue is found in areas where tension is exerted from many different directions, eg skin and in the joint. Elastic connective tissue The main fibers that form this issue are elastic in nature. These fibers allow the tissues to recoil after stretching. This is especially seen in the arterial blood vessels and walls of the bronchial tubes. 20 Elastic connective tissue Dense irregular 21 Dense regular connective tissue 22 Lecture Four: Blood blood is a specialized connective tissue consisting of cells and fluid called plasma. The bone marrow produces all blood cells. The blood circulates in the vascular system of a human. 23 Functions of blood 1.Supply of nutrient to cells 2.Transportation of O2 &CO2 in the body 3.Protects from infection 4.Removing waste material e.g urea ,CO2 5.Clotting 6.Regulation of body Temp. 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 24  Components of blood 1.Blood cells (45%) Red blood cells (erythrocytes) White blood cells (leucocytes) Platelets (thrombocytes) 2. Plasma (55%) Characteristics of RBCs 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 of RBC is to transport O2 &CO2 White blood cells (leukocytes) They are colorless 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) 25 Function of WBCs These are the cells of the immune system that are involved in protecting the body against infectious diseases Types of WBC - Granulocytes These WBC have granules in their cytoplasm Granulocytes include neutrophils, eosinophils, and basophils - Agranulocytes These are without granules in their cytoplasm They include monocytes and lymphocytes The most common type of white blood cell is the neutrophil, which accounts for 55 to 70 % of the total white blood cell count.They have a multi-lobed nucleus, which consists of three to five lobes connected by slender strands. The other major type of white blood cell is a lymphocyte. There are two main populations of these cells. T lymphocytes help regulate the function of other immune cells and directly attack various infected cells and tumors. B lymphocytes make antibodies, which are proteins that specifically target bacteria, viruses, and other foreign materials. Lymphocytes are round cells that contain a single, large round nucleus. Normal distribution of WBCs (%)  neutrophil 55 to 70 %  lymphocyte 20 to 40 %  Monocyte 2 to 8 %  Eosinophil 1 to 4 %  Basophil 0.5 -1 % 26 Neutrophils Eosinophil 27 Basophil less than 0.5% of the total count contain coarse, dark blue granules. The nucleus is bi- or tri-lobed, but it is hard to see because of the number of coarse granules that hide it.It is responsible for immune system &allergic reaction. Lymphoctes 28 Monocytes Monocytes are the largest cells of the blood , and they make up about 7 percent of the leukocytes. The nucleus is relatively big and tends to be indented or folded rather than multi-lobed. It is arise in bone marrow. Monocytes leave the bone marrow and circulate in the blood. After a period of hours, the monocytes enter the tissues, where they develop into macrophages 29 Platelets  Also called thrombocytes  Platelets are not cells, they are fragments of large cells  Nucleus is absent  Random shaped  2-4 micron size( smallest cells of blood )  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 Functions  Formation of blood clots and stops bleeding. 30 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 Slides for further learning 31 32 33 34