Galala University BMS111 Revision 3 Fall 2024-2025 PDF

Revision 3 BMS111 Prof. dr. Manal Shaaban Hafez Professor of Histology and Cell Biology Faculty of Medicine, Fall 2024-2025 Galala University gu.edu.eg  Cartilage ✓Definition: a specialized supportiv...

Revision 3 BMS111 Prof. dr. Manal Shaaban Hafez Professor of Histology and Cell Biology Faculty of Medicine, Fall 2024-2025 Galala University gu.edu.eg  Cartilage ✓Definition: a specialized supportive connective tissue with rubbery (firm) non vascular matrix. ✓ Histologically; Formed of : 1. Cells 2. Extracellular matrix composed of: - Fibers (type II collagen fibrils) - Ground substance contains (75% tissue fluid) to allow diffusion of nutrients  General histological characteristics ✓Cells are widely separated by abundant extracellular Pericondrium matrix (ECM). ✓The cartilage is generally avascular (have no blood vessels ) ✓The cartilage has poor healing and repairing capacities ✓The cartilage is covered from outside by perichondrium for nutrition and repair ✓ The perichondrium is absent in articular cartilage of joints & its nutrition from synovial fluid in in joints. ✓ The perichondrium is essential for repair and regeneration of cartilage especially in young age Pericondrium  Cartilage: Types of cells A. Chondroblasts B. Chondrocytes  Types of cells Chondroblasts Chondrocytes Old, mature Origin: UMC Origin: Chondroblasts Site: present at inner layer of Site: present deeper in the cartilage matrix perichondrium and are dividable cells and are dividable cells Structure: Flat or oval active cells. Structure: rounded cells inside lacunae (Protein forming cells) singly or in groups (cell nests) Actively secreted collagen type II They are less active than chondroblasts Function: synthesize cartilage matrix Function: Maintenance of cartilage matrix. then, Chondroblasts change into chondrocytes when they are trapped inside lacunae.  Hyaline cartilage Elastic cartilage Fibro-cartilage (Most common) Perichondrium Covered by Covered by NO perichondrium perichondrium perichondrium Matrix homogenous & heterogenous & Scanty containing basophilic containing basophilic containing parallel bundles of type II collagen fibrils type II collagen fibrils + collagen fibers type I abundant elastic fibers with rows of (Flexible). chondrocytes inside lacunae in between. Sites Ends of long bone , Ear pinna, Intervertebral discs Ends of the ribs, External ear, Trachea & bronchi Eustachian tube  General histological characteristics Definition: a specialized supportive connective tissue with Hard (solid) matrix. Bone covered externally by Periosteum & lined from internal surface by Endosteum Formed of: 1- Bone cells 2- Solid ECM : calcified (calcium & phosphate )& less tissue fluid (25%) + collagen type I Bone tissue is highly vascular Functions: 1. Protects and supports vital organs of the body as brain and spinal cord. 2. Storage site for calcium and phosphate. 3. Contains bone marrow which acts as a haemopoietic organ. 1. Osteogenic cells: present within inner layer of periosteum and endosteum. 2. Osteoblasts: Present side by side on the surfaces of bone (periosteum and endosteum). 3. Osteocytes: within the matrix, in-between bone lamella, Singly inside lacunae. 4. Osteoclasts: are present on the surface of bone (Endosteum) , in cavity called Howship`s lacunae.  Types Of Bone Tissue A.Compact bone & B. Spongy bone  Compact Bone 1) Compact bone: bone lamellae are regularly arranged. Haversian Systems (Osteons): The "Structural Units" of compact bone; formed of: ✓ Concentric bone lamellae around haversian canal (Blood vessels , nerves, CT). ✓ Osteocytes present in their lacunae in-between bone lamellae. ✓ Have one bone marrow cavity. Site: Shafts of long bones.  Spongy Bone (Cancellous ) 2) Spongy bones: branching and anastomosing bone trabeculae with multiple bone marrow cavities ✓ Bone lamellae are irregularly arranged (bone trabecula). ✓ Osteocytes in-between. ✓ Have no haversian system. ✓. Sites: Ends of long bones , Vertebrae, short & flat bones as Ribs and skull.  Structure of Neuron I- Cell body (perikaryon) II- Dendrites III- Axon Cell body : perikaryon Function: Trophic center 1. Reception of impulses from other neurons (Dendrites). 2. Conduction of the nerve impulse via the axon to other neurons.  Histology of cell body ( Perikaryon) A. Nucleus ✓Single ✓Spherical N ✓Large ✓Central ✓Pale vesicular ✓Euchromatin ✓Prominent nucleolus.  B. Cytoplasm 1. Nissl’s Bodies or Granules: LM: large basophilic granules scattered in perikaryon and dendrites but not in the axon (axon only for transport of neurotransmitters) EM: Free ribosomes & RER. ❑ Injury of nerve fiber: The nerve cells Nissl’s granules disappear due to their breaking down (chromatolysis). 2. Golgi Complex: LM: Stained with silver. - Network around nucleus in cell body EM: Well developed Golgi Complexes. 3. Mitochondria: ✓ Scattered in the cytoplasm. ✓ They are abundant in the axon terminals. ✓Are found in all parts of nerve cells 4. Neurofilaments & Microtubules: In cell body & Axon and dendrites. Supportive and maintain shape Neuro-tubules share in the transport of neurotransmitters.  Dendrites Axon Number Usually, numerous Single Length Short Long Branching Branching like a tree Not branching except at its terminal Axon terminals Diameter Become thinner as they Has a constant diameter subdivide into branches Impulse Towards the cell body Away from cell body direction Organelles Contain Nissl granules, Has mitochondria, neurofilaments mitochondria, neurofilaments and microtubules but No Nissl and microtubules granules Wall of blood vessel Inner Middle Outer  General structure of the tissue of the vascular wall 1-Tunica intima: A) Endothelium. B) Subendothelium. C) Internal elastic lamina. 2-Tunica media: A) Circular smooth muscle cells (Sheath of overlapped spindle-shaped cells with single central oval nucleus, containing contractile filaments; actin & myosin). B) Elastic fibers. C) External elastic lamina. 3- Tunica adventitia: A) Loose areolar connective tissue. B) Vasa vasorum ???? Structure Artery Vein Wall Thick Thin Lumen Round , narrow Collapsed , wide Intima Thick Thin Well developed Has no Int. elastic internal elastic lamina lamina Media Thick Thin External elastic Has no Ext.elastic lamina present lamina Adventitia Thin Thick Valves Absent Present  Connections between Arteries and Veins 1- Capillaries = An endothelial cell rests on a basal lamina rolls up forming a tube, surrounded by pericytes. 2- Sinousoids. 3- Arterio venous anastomosis. Blood capillary RESPIRATORY SYSTEM Divided into: I- Conducting portion. II- Respiratory portion. Faculty of Medicine 22  Respiratory portion 2 Formed of: 4 Respiratory bronchioles Alveolar ducts 1 Alveolar sacs Alveoli 3 Functions: Gas exchange between blood and inspired air. 23  Respiratory portion of the lung Gas exchange can take place in these portion. It is formed of :- 1. Respiratory bronchioles. 2. Alveolar ducts: Lined by low cubical epithelium surrounded by elastic fs. 3. Alveolar sacs. 4. Alveoli. Alveoli: ✓ The basic structural & functional unit of gas-exchange in the lung. ✓ They are minute air spaces that open into respiratory bronchioles, alveolar ducts & alveolar sacs. ✓ They have thin wall which allow CO2 & O2 exchange between blood & inspired air. ✓ Lined by alveolar epithelium.  Alveoli Alveolar epithelium: (1) Type I pnemocytes: The majority of alveolar epithelium. - L/M: Simple squamous epithelium. - E/M: Tight junction is present between adjacent Type I & Type II pneumocytes. Function: gas exchange. (2) Type II pnemocytes: They are secretory epithelial cells, Few in number (3%). - L /M: cuboidal cells Function: Synthesize and secrete pulmonary surfactant (to prevent lung alveoli collapse and keep them open). They can divide and regenerate both types of pneumocytes.  Skin Is the largest organ in the body constituting about 16% of the total body weight. It consists of two layers: 1. Epidermis (Outer layer= epithelium) 2. Dermis (Deeper layer= C.T.)  Epidermis Which type of epithelium? Keratinized stratified squamous epithelium. Epidermal cell types: 1. Keratinocytes 85% (Keratin formation) 2. Non keratinocytes ✓ Melanocytes (Melanin formation) ✓ Keratinocytes are attached to each other by ✓ Langerhans cells/ lymphocytes desmosomes & to the basement membrane by (Immunological function) hemidesmosomes. ✓ Superficial layers are continuously shed off. ✓ Merkel cells ✓ Deep layers are continuously dividing, accumulate (Mechanoreceptor for touch) keratin filaments & progress upwards.  Thick and thin skin Thick skin Thin skin Thick skin: Thin skin: 1- Thinner epidermis. 1- Thick epidermis. 2- Presence of: 2- Presence of: ▪ Hair follicles & Sweat glands. Sebaceous glands& 3- Site: Fewer sweat glands. Sole & Palm 3- Site: All over body except ………………  Liver Liver is the largest internal organs It is considered as a mixed exocrine and endocrine gland. ✓ Endocrine:- Synthesis of plasma proteins and coagulation factors. ✓ Exocrine:- Production of bile that facilitate the digestion of fats. LM & EM of the hepatocytes  Histological structure The cells are arranged in anastomosing cords of one or two cells. Blood sinusoids are present between the cell cords and are dilated spaces lined by:- 1.Fenestrated endothelium. 2.Permanent macrophage (Vonkupffer cells) The bile canaliculi are enclosed between the liver cells (Hepatocytes).  1-Classic liver lobule Definition: It is the structural unit of the liver. Shape: Hexagonal mass of liver cells with a vein in its center called central vein and portal areas at the corners. ✓ 2 bean-shaped organs enveloped by a thin CT capsule surrounded by adipose C.T. ✓ Formed of outer cortex & inner medulla. Outer cortex: ▪ It is the outer reddish (due to its rich blood supply) & granular (renal corpuscles) region beneath the capsule. Inner medulla: ▪ It is gray in color, consists of 6-12 medullary pyramids. ▪ Each pyramid has an apex directed to the minor calyx which open to major calyx to renal pelvis. ▪ All these urinary passages are lined by transitional epithelium. ✓ Consist of nephrons & collecting duct. ✓ The nephron is the structural & functional unit of the kidney produces urine. ✓ The collecting duct concentrates and carries urine to ureter. Nephron: is formed of; 1. Renal corpuscle. 2. Proximal convoluted tubule (PCT). 3. Loop of Henle. 4. Distal convoluted tubule (DCT). Outer cortex: contains renal corpuscle, proximal and distal convoluted tubules. Inner medulla: contains loops of Henel and collecting ducts. b- The Bowman's Capsule Double walled epithelial cup-shaped capsule. formed of 2 continuous layers: ✓ Outer (Parietal) Layer: lined e simple squamous epithelium. continuous with the simple cuboidal epithelium of proximal tubules PCT. ✓ Inner (Visceral) layer: formed of modified simple squamous epithelial cells called Podocytes. The visceral & parietal layers enclose the capsular space w receives the glomerular Filtrate. Thank You 36