Introduction to Body Structure PDF

INTRODUCTION TO BODY STRUCTURE 1 INTRODUCTION TO BODY STRUCTURE 2 This page intentionally left blank INTRODUCTION TO BODY STRUCTURE 3 INTRODUCTION TO HISTOLOGY INTRODUCTION TO BODY STRUCTURE 4 ILOs Upon successful complet...

INTRODUCTION TO BODY STRUCTURE 1 INTRODUCTION TO BODY STRUCTURE 2 This page intentionally left blank INTRODUCTION TO BODY STRUCTURE 3 INTRODUCTION TO HISTOLOGY INTRODUCTION TO BODY STRUCTURE 4 ILOs Upon successful completion of this course student will be able to: -Define histology. -Know the common types of microscopes &their applications in medical research. -Define magnification &resolution power of different microscopes. -Know the different types of stains -Know the mostly commonly used stain &their applications in medical field. Histology: is the subject dealing with the microscopical structure of normal tissue. The aim of histology course is: To help the student to understand the microanatomy of cells, tissues & organs. To make correlation structure with function. The study of histology is carried out by using microscopes of different types. The commonly used types of microscopes are: 1- Light microscope (L.M.) 2- Electron microscope (E.M.) 3- Light microscope &electron microscope differ in their optical resolution & magnification (enlargement). Resolution power: means the least distance at which two points appear separate from one another, if the distance is less the two points will appear as one point. Resolution power of the eye = 0.2 mm Resolution power of the LM. = 0.2 um Resolution power of the EM. = 0.2nm Maximum magnification power in case of L.M. is about X1000 while in case of EM. magnification power is about X100.000. Common stains used for Light microscopy Cells are colorless and usually indistinguishable by LM unless stained. 1) Acidic stain: e.g. eosin, it can stain basic structures, so these structures are acidophilic. 2) Basic stain: e.g. hematoxylin which stains acidic structures, so these structures are basophilic. 3) Neutral stain: e.g. Leishman's stain. It is a combination of an acidic & a basic stain for staining of blood cells. 4) Vital stain: It is used to stain a living structure inside a living animal such as staining of phagocytic cells using trypan blue or India ink. INTRODUCTION TO BODY STRUCTURE 5 5) Supravital stain: It can stain a living cell outside a living person e.g. Brilliant Cresyl blue which stains reticulocytes (immature RBCs) in a blood film. 6) Metachromatic stain: It will give a new color after staining which is different from its original color. The new color develops as result of a chemical combination between the stain & certain structures within the cell e.g. toluidine blue stains granules within mast cell with a violet color. Changing the original color of the stain at the end of staining process is called metachromasia. 7) Orcein stain for elastic fibers, they take brown color. 8) Silver stain: It can stain reticular fibers with brown or black color, it is also used to demonstrate Golgi apparatus in the cell. 9) Osmic acid: It stains myelin sheath with black colour. 10) Histochemical & cytochemical stains: These stains localize & demonstrate certain substances within a tissue or a cell depending on a biochemical reaction e.g. I. Glycogen can be stained red by Best's carmine. II. Lipids (fat) can be stained black with Sudan black & orange with Sudan III. III. Enzymes can also be stained using special methods e.g. acid & alkaline phosphatase enzymes INTRODUCTION TO BODY STRUCTURE 6 2-The cell The cell is the functional & structural unit of all living tissues. The cell is the smallest living structure which has vital properties such as growth, secretion, excretion, digestion, contraction, respiration & reproduction. The cells of the body are variable in shape, size& functions but they are similar in composition: I- Cytoplasm. II- Nucleus. I. Cytoplasm: It is formed of: 1) Cytoplasmic matrix: It is a colloidal solution containing proteins, carbohydrates, lipids, minerals & enzymes. 2) Cytoplasmic organelles: They are permanent minute living structures that are essential for the vital processes of all cells e.g., respiration, secretion, digestion. 3) Cytoplasmic inclusions: They are non- living temporary structures, not essential for the vitality of the cell. They are no more than substances stored within some cells e.g. glycogen, fat & pigments. Cytoplasmic Organelles They are classified according to presence or absence of surrounding membranes into: A) Membranous cell organelles 1. Cell membrane. 2. Mitochondria. 3. Endoplasmic reticulum (rough & smooth). 4. Golgi apparatus. INTRODUCTION TO BODY STRUCTURE 7 5. Lysosomes. 6. Peroxisomes. B) Non membranous cell organelles 1. Ribosomes 2. Cytoskeleton: a. Microtubules (centrioles & cilia) b. Filaments (Thin, intermediate& thick) A-Membranous cell organelles 1-Cell membrane Definition: It is an ultra- thin membrane that surrounds the cell i.e. it forms an envelope or a cover for the cell. L.M.: It is invisible by L.M as it is very thin (8-10 nm) but can be stained by Ag or PAS. E.M.: It appears as three parallel lines, two dark layers separated by a light one i.e. it is a Trilamellar membrane. The cell membrane has an outer covering rich in carbohydrates called cell coat. Molecular structure of the cell membrane: (Fig1) INTRODUCTION TO BODY STRUCTURE 8 The cell membrane is composed of lipids, protein & carbohydrate: 1. Lipids component: Cell membrane has two types of lipids: a) Phospholipid molecules b) Cholesterol molecules. The lipid component of the cell membrane allows passage of fat-soluble substances through it. 2. Protein component: Cell membrane contains two types of protein: a)Intrinsic protein ( integral protein): Intrinsic protein is present in the form of: Small particles A large globule which extends along the whole thickness of the cell membrane & acts as a pathway for water soluble substances. b)Extrinsic protein: It is represented by small molecules which are loosely attached to both surfaces of the cell membrane forming a non-continuous layer. 3. Carbohydrate component: They are oligosaccharides. They are either attached to protein molecule & form glycoprotein OR to lipid and from glycolipid. Glycolipid & glycoprotein are known as the cell coat or glycocalyx. Cell receptors are present among the cell coat; they are responsible for entrance of drugs, hormones & bacteria to the cell. Functions of cell membrane: a- It keeps the internal composition of the cell. b- Cell coat as a part of the cell membrane is responsible for cell adhesion, cell recognition, cell protection &cell immunity (functions of cell coat). c- It allows passage of substance through it by:- 1) Passive diffusion: (e.g. gases & water) 2) Facilitated diffusion: e.g. glucose. 3) Active transport: e.g. Na pumps outside the cell. INTRODUCTION TO BODY STRUCTURE 9 4) Selective permeability: By presence of receptors 5) Bulk transport (vesicular transport): Macromolecules enter & leave the cell by vesicular transport that involves changes in plasma membrane at a localized site & formation of vesicles from the cell membrane or fusion of vesicles with the cell membrane. Vesicular transport may be one of two processes: * Exocytosis: in which substances leave the cell to outside. * Endocytosis: in which substances enter the cell. If the substance that enters the cell is solid the process is called phagocytosis. Entrance of fluid is called pinocytosis.(Fig.2) 2- Mitochondria (Fig.3) INTRODUCTION TO BODY STRUCTURE 10 Definition: -It is a membranous cell organelle. -It is the powerhouse of the cell. -It is responsible for cell respiration & energy production. Number: varies according to cell activity e.g. liver cells contain 1000- 2000/ cell N.B. They are present in all cells except RBCs. Site: at site of the most activity e.g. apical part in ciliated cells. L M.: Mitochondria appear as granules, rods or filaments. They can be stained dark blue by iron hematoxylin & green by Janus green stain. EM: Mitochondrion appears as a vesicle rounded or oval in shape. It is covered with double membranes, separated by an inter-membranous space. Outer membrane is smooth while the inner one shows incomplete folds, shelves or cristae. Mitochondrial matrix fills the internal cavity of mitochondria. The matrix contains lipids, protein, carbohydrates, Ca & Mg as well as DNA & RNA. Oxidative enzymes are attached by heads to the cristae. Functions: 1. Mitochondria are the Powerhouse of the cell. They produce energy stored in the form of ATP & released at time of need. 2. They can form their own protein & can divide, as they contain DNA & RNA. INTRODUCTION TO BODY STRUCTURE 11 3- Endoplasmic Reticulum (Fig.4) Definition: It is a membranous organelle formed of flattened communicating vesicles & tubules that form reticulum [network] inside the cytoplasm. It is classified according to presence or absence of ribosomes into two types: a. Rough (granular) E.R. b. Smooth (agranular) E.R. Rough endoplasmic reticulum r Smooth endoplasmic reticulum ER s ER Site Protein forming cells e.g. Lipid forming cells e.g. liver & cells of pancreas, plasma cells, fibroblasts some endocrine glands. LM A basophilic (blue) structure due It cannot be seen. If it is abundant the to presence of ribosomes cytoplasm becomes acidophilic EM -A network of parallel flattened -Branching & anastomosing tubules & communicating vesicles & tubules vesicles. called cisternae. -It has no ribosomes. It is covered with ribosomes. -It is continuous with r ER Functions 1-Synthesis of protein by the 1-Lipid synthesis. help of the ribosomes 2-Steroid hormones synthesis. 2-Condensation & packing of the 3-Formation & storage of glycogen. protein e.g. in liver & muscles. 3-Budding of the packed protein 4-It helps muscle contraction by Ca in the form of transfer vesicles. pump. 4- It acts as intracellular pathway 5-Detoxification of drugs & hormones in 5 - It shares in the formation of liver. Lysosomes, by formation & 6-Acts as intracellular pathway. segregation of their hydrolytic enzymes. INTRODUCTION TO BODY STRUCTURE 12 4-Golgi Apparatus (Fig.5) Definition: It is a membranous organelle. It is considered as the secretory system of the cell. It is well developed in protein forming cells and secretory cells. LM: It is demonstrated by (Ag) stain. It appears as a dark brown network & fibrils around the nucleus (perinuclear) in nerve cell or between the nucleus & secretory pole (supranuclear) in secretory cell. e.g. pancreas. N.B. In sections stained with H&E. the area occupied by Golgi apparatus appears as unstained, area & so it is called negative Golgi Image.(Fig6) Negative Golgi Image INTRODUCTION TO BODY STRUCTURE 13 EM: It is formed of saucer-shaped flattened saccules stacked over each other forming a stack. Each stack has two faces:- 1- Immature convex surface, which is the forming surface (cis surface) that receives the transfer vesicles which carry protein from r E.R. 2- Mature concave surface from which secretory vesicles come out carrying condensed & modified protein. Also, other vesicles containing hydrolytic enzymes will come out &these are called Lysosomes Functions: 1- Concentration of protein formed by r E.R. 2- Modification of protein by adding sulphates or carbohydrates. 3- Discharge of secretion in the form of secretory vesicles 4- Isolation and packaging of hydrolytic enzymes in the form of lysosomes. 5- Formation & maintenance of cell membrane & cell coat. INTRODUCTION TO BODY STRUCTURE 14 5-Lysosomes (Fig.7) Definition: Membranous organelles rich in hydrolytic enzymes They are considered as the digestive system of the cell. Number: They are numerous in phagocytic cells e.g. white blood cells. Origin: The hydrolytic enzymes are formed in rER &carried in transfer vesicles to Golgi apparatus &come out as primary lysosomes LM: They can be demonstrated by using a special stain for the enzymes present within them, e.g. acid phosphates enzyme. EM: E.M picture of Lysosomes depends on their types. 1- Primary Lysosomes: These are the newly formed lysosomes coming from Golgi apparatus. They appear as small rounded homogenous vesicles. 2- Secondary Lysosomes: They result from fusion of primary Lysosome with phagocytic vesicle. They appear as heterogonous vesicles. They are of different types: a) Heterolysosomes: They result from fusion of a primary lysosome with a phagocytic vesicle containing food or bacteria. b) Multivesicular bodies: They result from fusion of primary lysosomes with INTRODUCTION TO BODY STRUCTURE 15 pinocytic vesicle containing fluid droplets. c) Autolysosomes: They result from fusion of primary lysosomes with vacuoles containing old organelles. d) Residual bodies: These are no more than secondary lysosomes containing the undigested remnants. They are either discharged outside the cell or accumulated within the cell as lipofuscin granules as in long lived cells e.g. cardiac muscle or nerve cell. Functions: 1- Digestion of nutrients within the cell. 2- Defensive function, destruction of any bacteria or virus. 3- Removal of any degenerated old organelles. 4- Lysis of the cells & all the body after death. 5- Change of inactive hormone into active one. e.g. in thyroid gland. 6- Help the sperm to penetrate the ovum. B-non-membranous cell organelles 1- Ribosomes Definition: Ribosomes are non-membranous cell organelles. They are formed within the nucleolus. Their chemical composition is ribonucleoprotein=rRNA +protein. LM: (Fig 8) They are very minute structures (15-20nm) difficult to be seen by L.M. They appear as basophilic structures by H&E when they are numerous, due to presence of ribosomes Fig 8 INTRODUCTION TO BODY STRUCTURE 16 EM: Fig 9 Ribosomes are small electron dense particle It is formed of two subunits, a large one & a small one. Both are connected by m RNA. The large subunit has a central groove which is occupied by the newly formed polypeptide chain. Fig 9 There are three forms of ribosomes: I- Free ribosomes are diffusely scattered in the cytoplasm. It is common in immature cells e.g. stem cells. II- Polyribosomes: the ribosomes are connected by m- RNA in a spiral or rosette form. (Fig 10) III- III- Attached ribosomes: The ribosomes are attached by means of their large subunits to rER. Fig 10: Polyribosomes INTRODUCTION TO BODY STRUCTURE 17 Functions of Ribosomes:( Fig 11) * Ribosomes act as intracellular site where amino acids join forming polypeptide chains i.e., they are the site for protein synthesis. * Protein formed by free ribosomes is used within the cell while that formed by rER is used outside the cell (transfer vesicle→ Golgi →secretory vesicle → cell membrane → outside the cell). Fig: 11 2- Cytoskeleton A- Microtubules Definition: Non- branching & rigid hollow fine tubes formed of a protein called tubulin. L M: They are difficult to be seen by L.M. except by using special stains. EM: They appear as fine tubules that measure about 20-25nm in diameter. The length of microtubules can be changed by adding or removal of tubulin molecules at their end. Functions: 1- Maintenance of the cell shape e.g. platelets. 2- Intracellular vesicular transport. 3- Formation of mitotic spindle during cell division. 4- Elongation & movement of the cell. 5- Formation of centrioles, cilia & flagella. B- Centriole: (Fig:12) Definition: INTRODUCTION TO BODY STRUCTURE 18 They are derived from the microtubules. They are responsible for cell division. They are absent in non-dividing cells e.g. RBCs & nerve cells. Site: They are usually present near the nucleus in an area called centrosome. LM: They are visible by light microscope as dark paired short rods or dots after staining with iron hematoxylin. EM:( Fig 13) They appear as two short hollow cylinders (0.5x0.2um) perpendicular to each other. The wall of each centriole is formed of nine bundles. Each bundle consists of three microtubules (triplet). Functions: 1. Share in formation of mitotic spindle during cell division. 2. They are responsible for the formation of cilia & flagella. INTRODUCTION TO BODY STRUCTURE 19 C- Cilia Definition: Cilia are motile hair-like processes projecting over the cell surface, capable of moving fluids &particles along the surface. LM: The cilia appear as short, fine, hair-like structures arising from the free surface of the cell giving it a brush border. Development of cilia: Cilia develop from centriole, first by replication of it to give baby centrioles, one for each cilium. Each baby centriole moves toward the surface of the cell to become the basal body from which a cilium can grow. The basal body is similar to centriole in structure nine triplets microtubules. Two inner microtubules (doublet) grow upwards from each triplet pushing in front of them the free surface of the cell membrane. At the same time two single microtubules grow in the center (9x2+2=20), this part is called the shaft of the cilium. The third outer microtubule of each triplet of the basal body grows downwards forming the rootlets of the cilium that fix it (9x1=9). EM: Each cilium consists of three parts: (Fig 14) 1- Shaft of Cilium: It is a finger like projection over the cell surface covered by cell membrane. It contains nine doublets & two single microtubules (9x2+2=20). 2- Basal body: It is similar to centriole in structure formed of nine triplets (9x3=27). 3- Rootlets of Cilium: It is formed of nine single microtubules (9xl =9) which are present below the basal body. Fig:14 Cilia INTRODUCTION TO BODY STRUCTURE 20 Functions: 1- Cilia move in a wave like manner to move secretions or particles over the tissue surface e.g. in respiratory system &female genital system. 2- Cilia can modify & act as receptors for a stimulus e.g. in rods & cones in retina where they receive light. 3- Flagellum: it is a long cilium forming the tail of the sperm------------> motility. d- Filaments: Definition: They are minute threads that act as a part of the cytoskeleton which maintains the shape of the cell. LM : They are difficult to see except by using a special stain. EM : They are classified according to their diameter into: 1- Microfilaments (thin filaments): [actin] They are very fine strands about 6nm in diameter formed of a protein called actin. They are found in muscle & microvilli. They form a supporting network within the cell that helps to maintain its shape. 2- Intermediate filaments: They have a diameter of about 8-10nm. There are about 50 different types of intermediate, filaments in humans, e.g. a- Cytokeratin filaments are present in epithelial cells. b- Vimentin filaments are present in connective tissue & muscle. c- Desmin filaments are present in muscle. d- Neurofilaments are present in nerve cells. e- Glial filaments are present in glial cells. 3- Thick filaments: - Their diameter is about 15 nm. - They are formed of a protein called myosin & they are found in skeletal muscle. INTRODUCTION TO BODY STRUCTURE 21 Cell Inclusions They are classified into two groups: a- Stored food. b- Pigments. A- Stored food: The cell may store carbohydrates or lipids: 1. Carbohydrates: stored in the form of glycogen as in liver & muscles. LM: Glycogen cannot be demonstrated by (H&E) as it is water soluble, it can be seen if stained by special stain as Best's Carmine (red) or PAS (purple). 2. Lipids: Lipids are stored in the form of small droplets or large globules. Fat cells are the main site for storage of lipids, other cells like liver cells may contain fat. L M: Lipids cannot be demonstrated by (H&E) as it dissolves in xylol. Lipid can be stained orange by Sudan III & black by Sudan black. B- Pigments : either 1- Endogenous which are produced by the cell, i- Hemoglobin which is present in RBCs to carry gases. ii- Melanin which give the skin & hair their color. iii- Lipofuscin granules are accumulated residual bodies in long lived cells e.g. nerve cells & cardiac muscles. 2- Exogenous: enter the cell from outside as: Carotene pigments in carrots ----------->color fats in cells Dust& carbon particles in air ----------> blacken lungs. 3- Tissues of the Body ❖ There are four main tissues in the body, these are: 1- Epithelial tissue 2- Connective tissue 3- Muscular tissue 4- Nervous tissue INTRODUCTION TO BODY STRUCTURE 22 I-Epithelial Tissue This tissue is called epithelial tissue because it can cover surfaces or line cavities all over the body. o General characters of epithelial tissue: 1- It may develop from ectoderm, mesoderm or endoderm. 2- The epithelial cells rest on a basement membrane (B.M.) which may be clear or not clear. 3- No blood vessels can enter in between epithelial cells, but nerves can, so epithelial tissue is avascular tissue. 4- Epithelial tissue receives nutrition by diffusion from the underlying connective tissue. 5- Epithelial tissue consists of numerous crowded cells with minimal intercellular substance between the cells that form continuous sheets, which cover surfaces or line cavities &is called surface epithelium. 6- Epithelial tissue may be modified to give secretion & is called glandular epithelium. 7- Epithelial tissue may modify to receive sensation & is called neuroepithelium & may acquire a contractile function & is called myoepithelium. 8- Epithelium can regenerate in a short time i.e. there is a continuous process of regeneration. o Epithelial tissue is classified into: I- Surface epithelium. II- Glandular epithelium. III- Neuro-epithelium IV- Myo-epithelium. I- Surface epithelium Surface epithelium is classified according to its number of layers into: a) Simple epithelium. b) Stratified epithelium. INTRODUCTION TO BODY STRUCTURE 23 a- Simple Epithelium Definition: It is formed of one layer of cells resting on basement membrane. It is divided according to shape of cells into: 1- Simple squamous epithelium 2- Simple cubical epithelium 3- Simple columnar epithelium 4- Simple columnar ciliated epithelium 5- Pseudo-stratified columnar epithelium POC 4-Simple 1-Simple squamous 2-Simple cubical 3-Simple columnar epithelium columnar ciliated Shape Flat Cube-like -Tall cells Tall cells of cells Flat nucleus Central carry rounded -Basal oval cilia nucleus nucleus -Basal oval nucleus Functi Smooth surface Secretion Secretion Movement ons (easy movement) Reabsorpti Absorption of Thin surface on (microvilli particles (gas &fluid e.g. intestine) or fluids exchange) over the surface Sites Mesothelium[pleu Thyroid -Stomach -Lung ra, pericardium follicle -Intestine bronchiole &peritoneum] Small -Goblet cells s Endothelium[hear ducts of [secrete t &blood vessels] salivary g. mucous -Uterus Lung alveoli Renal which Bowman's convoluted accumulates -Fallopian capsule of kidney tubules in its apex] tubes Hanaa.AK. INTRODUCTION TO BODY STRUCTURE 24 5-Pseudostratified Columnar Epithelium: It is actually a simple epithelium as all the cells rest on the B.M. It is formed of crowded cells. Nuclei are present at more than one level; this gives the epithelium a false appearance of being stratified. POC a-Pseudostratified b-Pseudostratified c-Pseudostratified columnar non-ciliated columnar ciliated columnar ciliated with motile cilia with non-motile &goblet cells cilia Sites 1- male genital system Respiratory epithelium Epididymis Nose (vas deferens). Larynx 2- Membranous part of Trachea male urethra Bronchi Hanaa.AK. Pseudostratified columnar epith. b- Stratified Epithelium: Definition: Epithelium is formed of more than one layer, the basal layer resting on the B.M. It is classified according to shape of the top layer into:- 1- Stratified squamous epithelium. 2- Transitional epithelium [stratified cuboidal]. 3- Stratified columnar epithelium. 4- Stratified cubical epithelium. INTRODUCTION TO BODY STRUCTURE 25 Function: The main function of stratified epithelium is protection. 2- Transitional 1- Stratified Squamous Epithelium Epithelium Number of 5-30 6-8 [empty bladder] 3-4 [full layers bladder] Basement Clear & wavy Non-clear, non-wavy membrane Basal cell Columnar with basal oval nuclei High cuboidal cells with rounded layer Intermediate Crowded polygonal cells with polyhedral with rounded layers central rounded nuclei nuclei Minimal intercellular substance. wide intercellular spaces Cells are held together with containing mucous like desmosomes. substance which helps gliding They gradually decrease in size of the cells over each other. NO desmosomes Cells become flat in full bladder Top layer Flat cells with flat nuclei. Cells are dome shape with upper convex, lower concave surface & have rounded nuclei, Some cells are binucleated. The top layer is covered with mucous to protect against the action of urine. Types Non-Keratinized Keratinized One type: In full bladder the cells of the top change in number of layers is due layer gradually to gliding of cells help of mucus die& change present between the cells so the into keratin number of layers decrease & the scales. surface area increase. Sites Line any wet Skin & dry Urinary bladder, ureters, some surface opening opening over it parts of urethra, renal calyces and over the skin 1-Epidermis of renal pelvis 1-Oral cavity skin. 2-Oesophagus 2- External ear. 3- Cornea. 3- Nasal orifices. Functions Protection Protection &accommodation (distensibility) INTRODUCTION TO BODY STRUCTURE 26 3- Stratified Columnar Epithelium: Like stratified squamous epithelium , but the number of layers is fewer & the top layer is formed of columnar cells which may be ciliated or not ciliated: - a- Stratified columnar ciliated epithelium:(Fig15) Sites: Fetal esophagus (a rare type). Fig:15- Stratified columnar ciliated epithelium b- Stratified columnar non ciliated epithelium:(Fig 16) Sites: 1- Recto-anal junction. 2- Large ducts of glands. 3- Male urethra (penile part). Fig16: Stratified columnar non ciliated epithelium: 4- Stratified Cubical Epithelium: (Fig17) It is a rare type of epithelium which is formed of few layers of cells, may be only two layers of cubical cells as in ducts of sweat glands Fig17 INTRODUCTION TO BODY STRUCTURE 27 Definition: It is a type of epithelium which modifies to act as a gland & give secretion. Classification of glandular epithelium according to: 1-Presence or absence of duct: a) Exocrine gland (salivary glands): The exocrine gland is formed of secretory portion & duct system b) Endocrine gland, ductless gland,(thyroid gland): NO duct system. Their secretion is called hormones. Secretion is carried by blood. c) Mixed gland (pancreas): The gland is formed of two parts exocrine part & endocrine part 2-Number of cells forming the gland: a) Unicellular gland, formed of one cell (goblet cell) b) Multicellular glands formed of many cells (all glands) 3-Type of secretion: a) Watery secretion (Sweat gland) b) Serous secretion: The secretion is watery but contains enzymes e.g. parotid gland & pancreas. c) Mucous secretion: e.g. Salivary gland & goblet cells. d) Muco-serous secretion e.g. sublingual & submandibular gland. e) Fatty secretion e.g. sebaceous gland. f) Waxy secretion e.g. glands of external ear. h) Cellular secretion e.g. ovary (ova) &testis (sperms). 4-Mode (mechanism) of secretion: a) Merocrine secretion: The most common mechanism Secretion come out by exocytosis No changes in the cell e.g. pancreas. b) Apocrine secretion: The secretion is released surrounded by a part of cytoplasm & the cell membrane usually the apex of the cell INTRODUCTION TO BODY STRUCTURE 28 e.g. mammary gland & some sweat glands. c) Holocrine secretion: The secretion accumulates within the cell. The swollen cell ruptures & secretions come out with the cell components e.g. sebaceous glands. 5-Branching of the duct: a) Simple gland: The gland has a single non branching duct. b) Simple branched gland: The gland has a single non branching duct & a branched secretory portion. c) Compound gland: The gland has a branching duct system. 6-Shape of secretory part: a) Tubular: Secretory part is in the form of a long tube b) Alveolar (acinar):- Secretory part is rounded or ball shape. c) Tubuloalveolar:- Secretory part is flask shape. N.B. Since all exocrine glands consist of a secretory part & a duct system so they are classified into: i) Tubular : - Simple tubular glands e.g. intestinal glands. - Simple branched tubular glands e.g. fundic glands of stomach - Simple coiled tubular e.g. sweat glands. - Compound tubular glands e.g. kidney, liver ii) Alveolar: - Simple alveolar glands e.g. sebaceous glands. - Simple branched alveolar glands e.g. sebaceous glands. - Compound alveolar glands e.g. mammary gland iii) Tubulo-alveolar: - Simple tubulo-alveolar gland, not present in man. - Simple branched tubulo-alveolar glands e.g. lingual, labial glands (minor salivary glands). - Compound tubulo-alveolar glands e.g. major salivary glands (parotid) & pancreas. INTRODUCTION TO BODY STRUCTURE 29 III-NEURO-EPITHELIUM Definition: It is a specialized type of epithelium. It acts as a receptor. It consists of three types of cells Hair cells which receive sensation. Supporting cells for support Basal cells act as stem cells for regeneration. 1-Taste buds (Fig 17) in the tongue for taste sensation. 2-Organ of Corti in the ear for hearing. Fig17 Tast buds IV-MYO-EPITHELIUM Definition: It is a special type of epithelium, which has a contractile function The myo-epithelial cells are present around the base of secretory cells Between the cells & the basement membrane When they contract, they squeeze the secretory cells Help them to evacuate their secretion inducts of glands e.g. around salivary glands, mammary gland & sweat glands. INTRODUCTION TO BODY STRUCTURE 30 Cell polarity [Specializations] Cell modifications I. Apical Modifications 1- Microvilli :(Fig 18) - Finger like projections from the cell Membrane. - L.M: apical brush border. - EM: have a core of actin filaments which maintain its shape & help shortening & elongation of microvilli. - Site & function: Increase the apical surface area for absorption e.g., in small intestine Fig.18 2- Stereocilia: (solid= non- motile): (Fig:19) - Not true cilia but long microvilli. - L.M: hairlike processes from the free surface of some cells. - E.M: Have a core of actin filaments. - Function & Site: help absorption e.g. epididymis. Fig19: showing stereocilia of epididymis 3- Cilia: - L.M: hairlike processes which arise from the free surface of some cells. - E.M: have a core of 20 microtubules arranged as 9 peripheral doublets & 2 central singlets covered with cell membrane. - Function & sites: Their rhythmic beating propels fluids or particles in one direction e.g. trachea, bronchi & Fallopian tube. INTRODUCTION TO BODY STRUCTURE 31 4- Flagella: (Fig:20) The flagellum is an extra-long cilium that forms the tail of sperm & helps its movements. Fig:20 Flagella II. Lateral specializations= Cell junctions 1] Tight junction: a- Zonnula Occludens: (Fig 21) The 2 adjacent cell Membranes fuse completely at certain points to prevent passage of any substance between cells. It surrounds the apex of the cell like a belt. Fig:21 b- Fascia Occludens: It is patchy fusion of the 2 cell membranes (not like a belt) e.g. between endothelial cells. 2] Adherens junction= zonula adherens: - The 2 adjacent cell membranes are separated by a wide space (20nm) filled with adhesive cell coat material with condensed actin filaments at the cytoplasmic side. It surrounds the cell like a belt Function: It fixes adjacent cells & prevents their separation. INTRODUCTION TO BODY STRUCTURE 32 3] Macula Adherens= Desmosome Fig:22 - The 2 adjacent cell membranes are separated by a very wide space (30 nm) filled with adhesive substance. The cytoplasmic side is thickened forming attachment plates in which tonofilaments are inserted forming hair pin- like loops. It does not encircle the cell but appears as spot. Function: Strongest type fixes epithelial cells e.g. in skin. Fig:22 Desmosomes 4] Gap junction: [Communicating J.] = nexus.(Fig:23) - The 2 adjacent cell membranes are separated by a very narrow gap (2nm) but connected by narrow channels. - Function: allows passage of ions or impulses from one cell to the other e.g. cardiac &smooth muscles. N.B. If more than one junction is present between adjacent cells e.g. cells of small intestine it is called junctional complex. Fig:23 Gap junction INTRODUCTION TO BODY STRUCTURE 33 III. Basal specializations 1] Hemidesmosome 1/2 a desmosome at the basal part of basal cells. It fixes epithelium to basement membrane & connective tissue 2] Basement membrane: The membrane that connects epithelium to connective tissue. L.M: Red line (by PAS) or brown (by AG). It is either clear (thick) as in skin OR non- clear (thin) as in transitional epithelium. E.M: 2 components 1-Basal lamina formed mainly by the cell coat of epithelium (glycoprotein) &collagen fibers (IV) 2-Reticular lamina : consists of reticular fibers (type III collagen) & glycoprotein. - Functions: 1- Supports epithelium. 2- Fixes epithelium to connective tissue. 3- Controls passage of ions & nutrients e.g. kidney & lung. 3] Basal Infoldings: (Fig:24) The basal cell membrane shows invaginations Dividing the base of the cell into compartments Contain mitochondria to give energy for active transport of ions e.g. in kidney tubules. Fig:24 Basal infoldings INTRODUCTION TO BODY STRUCTURE 34 II-CONNECTIVE TISSUE The connective tissue is formed of 3 components: A. Cells. B. B. Fibres. C. Extracellular matrix in which cells and fibres are embedded. Origin of connective tissue: Mesodermal origin Characteristics of connective tissue: 1. Formed of widely separated cells with large amount of matrix. 2. Rich in blood vessels, nerves and lymphatics. Types of connective tissue: according to matrix Soft ----------connective tissue proper. Rubbery----- cartilage. Hard----------bone. Fluid----------blood. 1-Connective Tissue Proper Components of C.T. proper: A. Cells. B. Fibres. C. Extracellular matrix A- Connective Tissue Cells They are 2 types of cells: Fixed (stable, long lived) Free (transient, short lived) 1. Fibroblast. 1. Plasma cell. 2. Fat cell. 2. Mast cell. 3.Mesenchymal cell. 3. Leukocytes. 4. Reticular cell. 4. Free macrophage. 5. Pericyte. 6. Fixed macrophage. 7. Pigment cell. INTRODUCTION TO BODY STRUCTURE 35 POC UMC Pericyte Fibrobla Fibrocyt Reticul Pigment st es ar cell cell Origin ---- UMC UMC UMC UMC Macroph &Pericyt ages e Sites Mesenchy Around Commonest C.T. Stroma Dermis mal tissue blood cell of of in embryo vessels organs skin Shape Branched cells with many processes Spindle Small &branched Cytoplasm Pale Pale Dark Pale Pale Shows basophilic basophili Basop basop basophi Granules c hilic hilic lic Nucleus Oval, pale Oval, pale Oval, Oval, Rounde Rounded &+nucleol &+nucleol pale dark d &pale us us &+nucl &pal eolu e s EM Few Few Rich in r Less r Dep Melanos organell organelles ER ER ends omes es Gap &G &Golgi on Many junctions olg app activ ribosomes i ity app Functions Differentia a-After 1-Form Change 1-Form 1-Store te to 1- injury it can C.T. to active reticula melanin C.T. cells differentiate matrix fibroblas r fibres 2-Give 2- Blood to &fibres t during 2-Act colour cells 1-fibroblast 2- healing as 3- 3-Smooth 2- Produce &after phagoc Protectio m. Endotheliu growth wound ytic cell n from 4- m factor 3-Act ultra Endotheliu 3-Smooth which as violet m m. stimulate antigen rays b- It can s present contract formatio ing cell &cause n of C.T. vasoconstri especiall ction y after injury INTRODUCTION TO BODY STRUCTURE 36 POC Adipocyte Adipocyte Mast cell Plasma cell Macrophage Unilocular Multilocular [Fixed &free] Origin UMC UMC UMC Active B- Blood monocyte Lymphocyte Sites white adipose Brown Around In lymphatic Fixed in CT. C.T adipose C.T. blood vessels tissue called in histiocyte respiratory Free in liver, &digestive skin, lung system &nervous tissue Shape Large oval Small oval Large oval Large oval Large with or rounded irregular outline Nucleus Flat Central- Small central Eccentric Dark eccentric perip rounded nucleus ,nucleus kidney shape heral cartwheel or nucleus clock-face appearance Cytoplas Minimal Much Basop Basophilic Pale m cytopla cytop hilic No granules basophilic sm lasm Granu Negative Special Large fat Many fat lar Golgi stain vital droplet dropl (coars Metachromat stain[tryp Signet ets e ic staining an blue] ring No signet granul with appear ring es) Toluidine ance by appear blue H&E ance E.M. Many Few Well Rich in r ER Rich in riboso ribosom develope Well lysosom mes es d Golgi developed es Few Many apparatu Golgi mitocho mitocho s apparatus ndria ndria Rich in cytochro me enzymes Function Fat storage Break Secretion Formation Phagocytosi s Support down of of &secretion s of Heat fat Heparin of foreign insulation Release Secretion antibodies bodies Energy of heat of Formation production Histamin of e multinucl Secretion eated of ECF giant (Eosinop cell hil Acts as Chemota antigen ctic presentin Factor) g cell Secretion of cytokines &collage nase enzyme INTRODUCTION TO BODY STRUCTURE 37 All types of leukocytes can be found in CT Cells responsible for immunological reaction are macrophage, mast cells, leukocytes &plasma cells. B- Connective Tissue Fibres Three types: I. Collagenous fibres. II. Elastic fibres. III. Reticular fibres. White collagenous Yellow elastic Reticular fibers fibers Structural collagen Elastin Type III collagen protein Fibers Fibroblasts Fibroblasts Fibroblasts forming cells Chondroblasts Chondroblasts Reticular cells Osteoblasts Smooth muscle Smooth muscle Shape LM. Wavy branching bundles Single, thin &branching Delicate ,thin & –non branching fibers branching Staining Eosin Acidophilic- Eosin: PINK. Ag black /fresh pink. Orcein: brown. PAS purple Mallory’s blue. Van Geison: Van Geison Red. yellow. Fresh: colorless - white Fresh yellow Functions Resists stretch strength Elasticity [stretchable] Support with flexibility &allow movement of cells INTRODUCTION TO BODY STRUCTURE 38 c- Extracellular Matrix Structure: Extracellular matrix is formed of 1) Ground substance 2) Tissue fluid. 1- Ground substance: It is the major ‘packing’ component of connective tissue It surrounds the cells and fibres It is colourless, gel-like substance which is highly hydrated. Secreted mainly by fibroblasts. It consists of glycoproteins, glycosaminoglycan, and hyaluronic acid 2-Tissue fluid: Derived from capillaries through its pores. It is similar to blood plasma except for the absence of plasma proteins. Functions: 1- Acts as a medium for the transfer of nutrients &waste materials between connective tissue cells and blood. 2-Acts as physical barrier prevents the spread of microorganisms. Staining: Ground substance can be stained by: Ag (brown). Toluidine blue [purple -metachromatic stain] Types of Connective Tissue Proper Types: 1) Loose (Areolar) Connective Tissue: i. Structure: All types of connective tissue cells mainly fibroblasts, macrophages, fat cells, and mast cells. All types of fibres mainly white collagenous fibres. INTRODUCTION TO BODY STRUCTURE 39 Matrix is most abundant with potential cavities (areolae) which can be filled with fluids or gasses. ii. Sites: Under epithelium; subserous, dermis of skin, submucosa. Around blood vessels. Fills spaces between other tissues. iii. Functions: Support epithelium, blood vessels and nerves. 2) Adipose connective tissue: i. Structure: Large number of fat cells forming lobules separated by connective tissue septa of collagen and elastic fibres. ii. Types: white and brown adipose CT. White Brown (unilocular) (multilocular) Fat cells Large. Small. One droplet of lipid. Many droplets of lipids. Few mitochondria. Many mitochondria. Flat peripheral nucleus. Spherical central nucleus Colour White Brown due to: 1. Rich in blood vessels. Nucleus 2. Cells are rich in mitochondria full of of fat cell cytochrome pigment. Sites 1. Under skin. In foetus and newborn: 2. Around kidney and blood 1. Interscapular region. vessels. 2. Axilla. 3. Mesentery. 3. Mediastinum. In adults: only around thoracic aorta. Functions 1. Synthesis & storage of fat. 1. Heat generation. 2. Support of kidney and blood vessels. 3. Heat insulator. INTRODUCTION TO BODY STRUCTURE 40 3) Reticular connective tissue: i. Structure: formed of. Reticular cells which are They are specialized fibroblasts connected by desmosomes, Reticular fibres forming a network, so it is stained brown by Ag. ii. Sites: in the stroma of: Lymphatic organs as spleen and lymph nodes. Bone marrow. Glands as liver. iii. Function: support cells in its sites. 4) Mucoid connective tissue (Fig:25) i. Structure: formed of Mesenchymal cells & fibroblasts that communicate with their processes. Jelly like ground substance huge in amount, rich in mucus, hyaluronic acid and glycoprotein called Wharton's jelly. ii. Sites: Umbilical cord. Pulp of growing tooth. Vitreous humour of eye. Fig:25 Mucoid C.T Mucoid CT iii. Function: protects nearby structures from pressure. 5) White fibrous connective tissue: (Fig 26) i. Structure: Mainly formed of fibroblasts and collagen fibres with very minimal ground substance. INTRODUCTION TO BODY STRUCTURE 41 ii. Types: Regular Irregular Structure Collagen bundles are Collagen bundles are irregularly arranged forming parallel to each other network with fibroblasts in between. and to the fibroblasts in between. Sites Tendons. Periosteum, perichondrium. Cornea. Sclera. Functions Resists stretch in one Resists stretch in different directions. direction. 6) Fig 26: diagram showing types of white fibrous C.T Yellow elastic connective tissue: (Fig:27) i. Structure: formed of connective tissue cells mainly fibroblasts and connective tissue fibres mainly elastic fibres so it appears yellow in fresh state and can be stained brown with orcein. ii. Sites: Aorta and large vessels. Bronchi and bronchioles. Ligamentum nuchae and ligamentum flavum. iii. Function: gives flexible support. Fig:27 INTRODUCTION TO BODY STRUCTURE 42 This page intentionally left blank INTRODUCTION TO BODY STRUCTURE 43 INTRODUCTION INTRODUCTION TO BODY STRUCTURE 44 Planes Movements Marieb / Shier INTRODUCTION TO BODY STRUCTURE 45 TERMINOLOGY Anatomical position: all the anatomical descriptions are based on a position in which the man is standing, with his face & palms of hands directed forward & the feet are close to each other. Anatomical planes & directions: Median (sagittal) plane: a vertical plane which divides the body at the midline into Rt & Lt equal halves. According to this plane & the planes parallel to it (paramedian or parasagittal planes) the body is divided into medial (near the midline) & lateral (away from midline). Coronal plane: a vertical plane which divides the body into anterior (in front of the plane) & posterior (behind the plane). Transverse (horizontal) plane: which divides the body into superior (upper) & inferior (lower) parts. Anatomical descriptions: In addition to the previous terms, others could be used as: Superficial & deep: near or away from the surface. External & internal: outside or inside. Proximal & distal: near or away from the trunk. Terms of movements: Flexion & extension: moving 2 ventral surfaces towards or away from each other. Adduction & abduction: movement towards or away from midline. Medial & lateral rotations: moving the anterior side towards or away from the midline. N.B.: other terms of movements may be used in specific sites. INTRODUCTION TO BODY STRUCTURE 46 Skin and fascia Marieb INTRODUCTION TO BODY STRUCTURE 47 SKIN & FASCIA SKIN Layers: it is formed of 2 layers: Epidermis: outer tough layer. Dermis: inner layer containing hair follicles, sweat glands, nerves, blood vessels & lymphatics. Functions: Protection from external environment. Sensations. Regulation of body temperature. SUPERFICIAL FASCIA ❖ Formed of loose connective tissue & fat. ❖ It also contains nerves, blood vessels & lymphatics, transmitting it to skin. ❖ It is absent in specific sites, e.g.: eye lids & scrotum. Functions: Fat store. Regulation of body temperature (fat prevent heat loss). In females, it contains the mammary gland forming the breast. DEEP FASCIA ❖ It is formed of dense connective tissue, to surround the deeper structures. ❖ It is well developed in limbs, especially around the joints (to grasp the different structures passing) & in the palm of hand & sole of foot (for protection). ❖ It is poorly developed in sites which need expansion, e.g.: face and thoracic and abdominal walls. INTRODUCTION TO BODY STRUCTURE 48 long short flat irregular pneumatic Sesamoid Growing long bone Marieb / Shier INTRODUCTION TO BODY STRUCTURE 49 BONES Types of bones: Type Description Example Long A bone with a shaft (diaphysis) & 2 ends (epiphysis) Humerus & femur Short Small bone Carpal bones Flat A bone with 2 surfaces Scapula Irregular A bone which does not fit the previous 3 types Vertebrae Pneumatic Special type, which is filled with air Maxilla Sesamoid Special type, which is found in a tendon of a muscle Patella Ossification of bones: Membranous: a connective tissue membrane will ossify into bone (e.g.: clavicle). Cartilaginous: a membrane will be transformed into cartilage model which will ossify into bone (e.g.: all bones of the limbs except clavicle). Growing long bone During development of long bones, it is formed of a membranous model, which mostly changes to a cartilage. Before birth, the shaft is transformed into bone, it begins by a primary center of ossification. After birth, each end is transformed into bone, it begins by a secondary center of ossification. A disc of cartilage persists between the shaft and each end, it is called epiphyseal plate of cartilage. The epiphyseal plate of cartilage add new cells to the shaft, this will increase bone length. The newly formed part of the shaft (near epiphyseal plate of cartilage) is called metaphysis. Later, the epiphyseal plate of cartilage ossifies, this will stop bone lengthening. Usually the 2 epiphyseal plates of the same bone do not ossify at the same time. One (non growing) end ossifies around the age of 19 years in males (17 years in females). The other (growing) end will ossify around the age of 21 years in males (19 years in females) with variations. The bone is covered by a periosteum. Periosteum add new cells deep to it, causing an increase in bone width. The bone shows a cavity. This cavity is lined with endosteum and contains bone marrow, which is responsible for formation of blood cells. INTRODUCTION TO BODY STRUCTURE 50 Suture Syndesmosis gomphosis Primary cartilaginous Secondary cartilaginous Hinge Pivot Modified hinge ellipsoid Saddle Ball & socket Synovial Joint features Ken Hub / McKinley & O’Loughlin / Shier / Marieb / Tortora & Nielsen INTRODUCTION TO BODY STRUCTURE 51 JOINTS Definition: meeting between 2 or more bones (or cartilages). Types: according to the tissue between the bones the joints is classified into: Fibrous: a fibrous tissue connect the 2 bones, further divided into: Type Features Example Syndesmosis Allows minimal movement Inf tibiofibular joint Does not ossify with age Suture Allows minimal movement Sagittal suture (in skull) Ossify with age Gomphosis Allows no movement Between teeth & gums Does not ossify with age Cartilaginous: a cartilage connects the 2 bones, further divided into: Type Features Example Primary Formed of hyaline cartilage Epiphyseal plate of cartilage cartilaginous Allows no movement Ossifies with age Usually found away from midline Secondary Formed of fibrocartilage Intervertebral disc cartilaginous Allows minimal movement Usually does not ossify with age Usually found in midline Synovial: the 2 bones are connected with a capsule filled with synovial fluid, further divided into: Type Features Example Plane Allows only gliding movement Acromioclavicular Hinge Uniaxial: allows only flexion & extension Elbow Pivot Uniaxial: allows only rotation Sup & inf radioulnar Modified hinge Biaxial: allows flexion & extension + minimal rotation Knee Ellipsoid Biaxial: allows flexion & extension + adduction & Wrist abduction saddle Multiaxial: allows flexion & extension + adduction & Carpometacarpal of thumb abduction + minimal rotation Ball & socket Multiaxial: allows flexion & extension + adduction & Shoulder abduction + rotation Hip Synovial Joint features: Articular cartilages: a layer of hyaline cartilage, covering the articular surfaces, for smooth movement. Capsule: it is formed of fibrous tissue, which connect the articular surfaces Synovial membrane: lines the capsule & covers intracapsular non articular structures. It makes the joint space closed & secretes synovial fluid, which is responsible for joint lubrication. Ligaments: strong fibrous tissue, for joint stability. These ligaments may be capsular (thickened part of capsule), intracapsular or extracapsular. INTRODUCTION TO BODY STRUCTURE 52 Skeletal Cardiac Smooth Types of skeletal muscles McKinley & O’Loughlin / Whitaker & Borley INTRODUCTION TO BODY STRUCTURE 53 CARTILAGE ❖ It is avascular dense connective tissue, with intercellular matrix. Types: Type Features Example Hyaline Large amount of matrix Epiphyseal plate of cartilage Articular cartilages Fibrocartilage (white) Little matrix Intervertebral discs Rich in collagen fibers Intraarticular cartilages firm Elastic (yellow) Rich in elastic fibers Auricle of ear malleable Epiglottis MUSCLES Types: Skeletal Smooth Cardiac Site Attached to skeleton Viscera except heart Heart Muscle fibers Striated Smooth Striated Innervation Somatic nerves Autonomic nerves Autonomic nerves Action voluntary Involuntary Involuntary SKELETAL MUSCLES Attachment of skeletal muscle: Origin: it is the beginning of the muscle, it is usually proximal & fixed. Insertion: it is the end of the muscle, it is usually distal & movable. Forms of attachments: Fleshy: the regular fleshy nature of the muscle. Tendon: cylindrical cord like fibrous tissue. Aponeurosis: flat sheet like fibrous tissue. Raphe: meeting of 2 muscles (usually in midline), in the form of a mixture of fleshy & tendinous fibers. Types of skeletal muscles: Type Features Parallel The muscle fibers are parallel from origin to insertion Fusiform Parallel muscle fibers with central dilatation Triangular The fibers attach by a wide origin & narrow insertion Circular The fibers form a circle Pennate Unipennate The fibers attach obliquely to the tendon from one side Bipennate The fibers attach to the tendon from 2 sides Multipennate Union of many bipennate parts Circumpennate Circular arrangement of multipennate INTRODUCTION TO BODY STRUCTURE 54 Heart Mckinley INTRODUCTION TO BODY STRUCTURE 55 CARDIOVASCULAR SYSTEM HEART ❖ It is a muscular organ which pumps blood to different parts of the body. ❖ It has 4 chambers (Rt & Lt atria & Rt & Lt ventricles). ❖ It is supplied by coronary arteries. Occlusion of a coronary artery may lead to angina. Parts: RT atrium It receives non oxygenated blood from different parts of the body (except the lungs) through SVC and IVC. It transmits it through Rt A-V opening (guarded by tricuspid valve) to Rt ventricle. Rt ventricle It receives non oxygenated blood from RT atrium. It pumps it through pulmonary artery (guarded by pulmonary valve) to the lungs where it is oxygenated. Lt atrium It receives oxygenated blood from lungs through pulmonary veins. It transmits it through Lt A-V opening (guarded by mitral valve) to Lt ventricle. Lt ventricle It receives oxygenated blood from Lt atrium. It pumps it through aorta (guarded by aortic valve) to different parts of body. BLOOD VESSELS Arteries: It is blood vessels transmitting blood away from the heart. It has an elastic wall, helping in its dilatation and constriction to regulate blood pressure. All the arteries carry oxygenated blood except pulmonary arteries which carry non oxygenated blood. The arteries divide into smaller arteries → arterioles → capillaries. Usually, the arteries anastomose with each other. Those who don’t anastomose are called end arteries. Occlusion of an end artery will lead to death of the part supplied by it. E.g.: in heart, lungs, kidneys, spleen, retina and CNS. INTRODUCTION TO BODY STRUCTURE 56 Circulations Pulmonary capillaries Portal circulation Tortora & Nielsen / McKinley & O’Loughlin / Martini / Marieb INTRODUCTION TO BODY STRUCTURE 57 Capillaries: Small thin walled blood vessels. It allows the movement of oxygen & nutrients from blood to intercellular tissues & CO2 & waste products in the opposite direction. Sinusoids: Wider than capillaries. It allows slow circulation. E.g.: liver, spleen, suprarenals and bone marrow. A-V shunts: Direct channels between arterioles and venules. It allows rapid circulation (as in temperature regulation) and not concerned with material exchange. E.g.: hands, feet and nose. CIRCULATIONS Systemic circulation: It is between the heart and different tissues of the body. Lt ventricle pumps oxygenated blood → aorta → arteries → arterioles → capillaries (material exchange with cells) → venules → veins → SVC & IVC → Rt atrium. Pulmonary circulation: It is between the heart and lungs. Rt ventricle pumps non oxygenated blood → pulmonary arteries → arterioles → capillaries (gas exchange with lung alveoli) → venules → pulmonary veins → Lt atrium. Portal circulation: Between the GIT & liver (interrupting GIT systemic circulation). Capillaries of GIT (carrying absorbed nutrients) → venules → veins → portal vein → divides → liver sinusoids (adjustment of nutrient levels and detoxication). So, the portal vein begins like a vein (union of smaller veins) and ends like an artery (giving divisions). INTRODUCTION TO BODY STRUCTURE 58 Lymph vessels Lymph nodes Tortora & Nielsen / McKinley & O’Loughlin / Marieb INTRODUCTION TO BODY STRUCTURE 59 LYMPHATIC SYSTEM ❖ In organs, the exchange occurs between capillaries and intercellular fluid. Part of the fluid is not drained back to the capillaries. Instead, it is collected in lymphatic vessels as lymph, which is filtered during its course in lymph nodes. Finally, it drains into the venous system. Lymph: It is the intercellular fluid drained with lymph vessels. It is clear and rich in lymphocytes. Lymph vessels (lymphatics): Larger than blood capillaries. The lymph capillaries unite → larger lymph vessels, which pass through the lymph nodes. Some organs are rich in lymphatics. E.g.: dermis and mucous membranes. Some organs are devoid of lymphatics. E.g.: CNS, bone marrow, cornea and epidermis. Lymph nodes: It is a collection of lymph tissues interrupting the lymph vessels course and filtering the lymph. They are usually found in entrance sites of body parts. E.g.: axillary lymph nodes for upper limbs, inguinal lymph nodes for lower limbs and cervical lymph nodes for head and neck. Some organs are considered modified lymph nodes, as they don’t have afferent lymphatics. They have a protective function against external threats. E.g.: tonsils and adenoids. INTRODUCTION TO BODY STRUCTURE 60 Nose & pharynx Paranasal sinuses Marieb / Tortora & Nielsen INTRODUCTION TO BODY STRUCTURE 61 RESPIRATORY SYSTEM NOSE Parts: Roof: narrow and separated from cranial cavity by thin perforated bone. Floor: wide and formed by the palate. Median septum: formed of post bony and ant cartilaginous parts. 2 lateral walls: show 3 shelf projections called conchae (sup, middle & inf), below each concha a meatus is found (sup, middle & inf). These meatuses receive the openings of paranasal sinuses. Ant nasal openings: in the face. Post nasal openings: to the pharynx. ❖ The nose is lined with respiratory epithelium (vascular and mucoid) for modification of inspired air. Except near the roof where it is lined with olfactory epithelium (smell receptors). PARANASAL SINUSES ❖ It is air filled spaces within some skull bones, connected to the nose and lined with respiratory epithelium. ❖ It is found in frontal, maxillary, sphenoid and ethmoid bones. ❖ It allows the enlargement of the skull bones without increase in weight ❖ Inflammation of these sinuses is called sinusitis, which may be a result of inadequate connection to the nose. PHARYNX ❖ It is a muscular tube posterior to nose (nasopharynx), oral cavity (oropharynx) and larynx (laryngopharynx). ❖ It extends from the base of skull to C6 vertebra. Parts: Nasopharynx: Lies behind the nose. It transmits air from the nose (anterior) to oropharynx (inferior). It communicates with the middle ear through Eustachian tube. It has a collection of lymphoid tissue called adenoids. Oropharynx: Lies behind the oral cavity. It transmits air from nasopharynx (superior) to larynx (anteroinferior) and transmits food from oral cavity (anterior) to laryngopharynx (posteroinferior). Laryngopharynx: Lies behind the larynx. It transmits food from oropharynx (superior) to esophagus (inferior). It has a collection of lymphoid tissue called tonsils. INTRODUCTION TO BODY STRUCTURE 62 Larynx, trachea and bronchi Lungs Alveoli Martini / Marieb INTRODUCTION TO BODY STRUCTURE 63 LARYNX ❖ It is formed of cartilages, membranes and muscles. ❖ It begins at C3 vertebra, as a continuation of oropharynx. It ends at C6 vertebra to continue as trachea. ❖ It shows 2 vocal cords which allow air passage, its vibration against expired air produces voice. TRACHEA ❖ It is 12 cm long and 12 mm in diameter. ❖ It shows C shaped cartilages in its wall to keep it open. ❖ It begins at C6 vertebra and ends at T4 vertebra by dividing into 2 bronchi (Rt & Lt). BRONCHI Rt bronchus Lt bronchus Short (2.5 cm) Long (5 cm) Wide Narrow More vertical More horizontal Divides into 2 bronchi before entering the lung Divide inside the lung Accordingly, foreign body is more commonly lodged in Rt than Lt bronchus. LUNGS ❖ 2 (Rt and Lt). ❖ Each is ½ cone shaped with an apex (sup) and base (inf). ❖ Each bronchus enters the lung divides into smaller bronchi → bronchioles → many divisions → alveoli (filled with air and surrounded by pulmonary capillaries for gas exchange. ❖ Structures entering the lungs: Pulmonary vessels for oxygenation: the artery carries non oxygenated blood and the vein carries oxygenated blood. Bronchus (or two). Bronchial vessels to supply the lung itself. ❖ Each lung is covered with pleura, which is a double layer of serous sac with thin film of fluid in between, for lubrication of the lung movement. Rt lung Lt lung Short Long Wide Narrow Larger smaller Shows 2 fissures Shows 1 fissure Formed of 3 lobes (sup, middle and inf) Formed of 2 lobes (sup and inf) Has a deeply concave base due to the presence of the liver inf to it Has a shallow concave base INTRODUCTION TO BODY STRUCTURE 64 Oral cavity Teeth Tongue Salivary glands Tortora & Nielsen / Marieb INTRODUCTION TO BODY STRUCTURE 65 DIGESTIVE SYSTEM MOUTH ❖ Its roof is formed of palate (ant: hard palate formed of bones and post: soft palate formed of muscles), both are covered with mucous membrane. ❖ Its floor is formed of muscles of oral diaphragm and covered with mucous membrane. ❖ It is continuous posteriorly with the oropharynx. ❖ It contains 2 U shaped gums (sup and inf), each is formed of fibrous tissue covered with mucous membrane. ❖ Each ¼ of gum contains 8 teeth in adults (2 incisors, 1 canine, 2 premolars and 3 molars). ❖ The vestibule: is the space between the gums and the cheeks. TONGUE ❖ It is a muscular organ covered by mucous membrane, with a tip (ant) and a root (post). ❖ The muscles are either extrinsic (attached from bones to tongue and moving it) or intrinsic (not attached to bones and changing tongue shape). ❖ The mucous membrane covering the tongue can feel general sensations (pain, temperature… etc). The dorsal surface shows taste buds (receptors) which can also feel taste sensations (salty, bitter… etc). ❖ The mucous membrane covering the inf (ventral) surface shows a fold connecting it to the floor of mouth called frenulum. SALIVARY GLANDS 3 pairs: Parotid: at the side of face, below the ear. Submandibular: deep to the mandible. Sublingual: in the floor of mouth. ❖ They are exocrine glands, secreting saliva by ducts into the oral cavity. ❖ Their secretion is stimulated by parasympathetic & inhibited by sympathetic innervation. PHARYNX ❖ See respiratory system. ESOPHAGUS ❖ It is a muscular tube (25 cm) extending from the laryngopharynx (at the level of C6 vertebra) to the stomach. ❖ It pushes the food by peristaltic movements. STOMACH ❖ It is the most dilatable part of GIT. ❖ It is usually J shaped. ❖ It has 2 openings; cardiac (connecting it to the esophagus and guarded by a physiological sphincter) and pyloric (connecting it to the duodenum and guarded by powerful anatomical sphincter), these sphincters allow the food passage from the esophagus → stomach → duodenum and not the reverse. ❖ It has 2 borders; right (lesser curvature) and left (greater curvature). ❖ It has 2 surfaces; anterior (facing liver and anterior abdominal wall) and posterior. INTRODUCTION TO BODY STRUCTURE 66 Esophagus and stomach Small intestines Large intestines Tortora & Nielsen INTRODUCTION TO BODY STRUCTURE 67 SMALL INTESTINES ❖ It is about 6 meters, and divided into duodenum, jejunum and ileum. Duodenum It is C shaped (10 inches, 25 cm long). It begins after the pyloric sphincter and ends by becoming jejunum. It is mostly fixed to the posterior abdominal wall. Parts: 1st part: 2 inches long, horizontal (extending from Lt to Rt). 2nd part: 3 inches, vertical (directed downwards). 3rd part: 4 inches, horizontal (extending from Rt to Lt). 4th part: 1 inch, vertical (directed upwards). It has an opening in the 2nd part (major duodenal papilla), which receive the liver and pancreatic secretions through hepatopancreatic ampulla, this opening is guarded by sphincter of Oddi. Jejunum It is about 2.5 meters long. It has a thick wall and a wide diameter (4 cm). It has many mucosal folds showing villi (for absorption of food) and rich vascularity. Ileum It is about 3.5 meters long. It has a thin wall and a narrow diameter (3,5 cm). It has less mucosal folds and less vascularity, but it has more lymphatics and surrounding fat. LARGE INTESTINES ❖ It is about 60 inches (1.5 meters). ❖ It has a 3 longitudinal muscle straps (Taenia coli), which is shorter than the large intestines causing it to form (sacculation), it also has a small fat pockets at its outer wall (appendices epiploicae). ❖ It has mucosal folds, which disappears in distension and has no villi. Parts: Cecum: 3 inches, rounded sac. Appendix: narrowest part of the GIT, extends from cecum for 1-7 inches. Ascending colon: 5 inches, on the RT side, directed upwards. Transverse colon: 20 inches, extending from Rt to Lt. Descending colon: 10 inches, on the Lt side, directed downwards. Sigmoid colon: 15 inches, lies in the pelvis. Rectum: 5 inches. Anal canal: 2 inches and guarded by internal (involuntary) and external (voluntary) sphincters. INTRODUCTION TO BODY STRUCTURE 68 Liver Biliary system Pancreas Spleen Shier / McKinley & O’Loughlin / Tortora & Nielsen INTRODUCTION TO BODY STRUCTURE 69 LIVER ❖ It is the largest gland in the body (about 1.5 kg in adults). ❖ It is pyramidal in shape, with the base directed to Rt and the apex directed to the Lt. ❖ It is formed of large Rt and small Lt lobes. ❖ It is supplied by hepatic vessels. It also receives portal vein transmitting blood rich in nutrients absorbed from GIT. ❖ The liver has an important function in managing the level of nutrients in blood, breaking toxins and it also secretes bile for digestion. BILIARY SYSTEM ❖ The bile is secreted from the liver in 2 (Rt & Lt) hepatic ducts. ❖ Both unite to form common hepatic duct. ❖ The hepatic duct meets the cystic duct. ❖ The cystic duct transmits bile from common hepatic duct to gall bladder for storage and concentration. It then transmits the concentrated bile in reversed direction to the common bile duct. ❖ The gall bladder is a cyst found below the inferior surface of the liver, it is formed of fundus (related to the anterior abdominal wall), body and neck which is continuous with the cystic duct. ❖ The common bile duct is formed by union of common hepatic duct and cystic duct. It descends to unite with the main pancreatic duct to form hepatopancreatic ampulla which opens in the duodenum. PANCREAS ❖ It is a mixed gland; endocrine (islets of Langerhans) secreting insulin directly in the blood, and exocrine secreting enzymes through ducts into the duodenum. Parts: Head: discoid, in the concavity of duodenum. Neck: narrow part. Body: extending from Rt to Lt. Tail: reaching the spleen. Ducts: Main pancreatic duct: It extends along the whole length of pancreas. It ends by uniting with common bile duct forming hepatopancreatic ampulla, which open in the duodenum. Accessory pancreatic duct: It drains part of the head of pancreas and open in the duodenum. SPLEEN ❖ It is a lymphoid organ related anatomically to the GIT. ❖ It is 12X6X3 cm. ❖ It has 2 surfaces (outer related to the diaphragm and 9-11 Lt ribs and inner related to abdominal viscera), 2 ends (ant and post) and 2 borders (sup and inf). INTRODUCTION TO BODY STRUCTURE 70 Kidney Urinary bladder Urethra Tortora & Nielsen / McKinley & O’Loughlin / Marieb INTRODUCTION TO BODY STRUCTURE 71 URINARY SYSTEM KIDNEY ❖ It is 12X6X3 cm. ❖ It has 2 ends (sup & inf), 2 borders (med & lat) & 2 surfaces (ant & post). ❖ Its function is to filter blood from waste products and excess water and secretes it as urine. ❖ It is formed of an outer part (cortex) and inner part (medulla). ❖ The unit of filtration is called nephron. It secretes urine in a collecting duct → minor calyces (8-12/ kidney) → major calyces (2-4/ kidney) → pelvis → ureter. URETER ❖ It is 25 cm long. ❖ It extends from the kidney to the urinary bladder. ❖ Part of it passes on the posterior abdominal wall, the other part passes on the pelvic wall. ❖ It has narrow sites, in which stone formation may occur. URINARY BLADDER ❖ It is pyramidal in shape with 4 surfaces (sup, post & 2 inferolateral). ❖ Its function is a urine reservoir. It usually gives an impulse for urination if filled with 300 cc, reaching 500 cc may lead to involuntary urination. ❖ It has a muscular wall lined with mucosa, to push the urine outwards. ❖ Its mucosa is sensitive to distension. The most sensitive part is the trigone (lining the post surface) which is richly innervated by autonomic nerves. ❖ It shows 3 openings; one for each ureter, and a 3rd opening for the urethra (neck of urinary bladder). Male urethra ❖ It is 15-20 cm long. Parts Prostatic 3 cm. Surrounded by prostate. This part receives ducts of the prostate & the 2 ejaculatory ducts Its upper part is surrounded by internal urethral sphincter (formed of involuntary muscles and innervated by autonomic nerves). Membranous 2 cm. Passes in perineum (superficial part of pelvis). It is surrounded by external urethral sphincter (formed of voluntary muscles and innervated by somatic nerves). Penile 10-15 cm. Passes in the corpus spongiosum of the penis. Female urethra ❖ 4 cm. ❖ It is wider than male urethra. ❖ Passes from the neck of urinary bladder to the vulva. INTRODUCTION TO BODY STRUCTURE 72 Testis and epididymis Male genital system Vas deference, seminal vesicles, ejaculatory ducts and prostate (post view) McKinley & O’Loughlin / Martini / Tortora & Nielsen INTRODUCTION TO BODY STRUCTURE 73 MALE GENITAL SYSTEM SCROTUM ❖ It is a skin pocket containing the testis. ❖ It is considered as an extension of anterior abdominal wall. ❖ It is suspended from the trunk to regulate the temperature of testis, so it does not contain any fat. TESTIS ❖ It is 4X2X1 cm. ❖ It lies in the scrotum. ❖ It is divided into about 200 compartments. ❖ Each compartment contains about 2 seminiferous tubules. ❖ Each seminiferous tubule is about 2 feet (60 cm) long. ❖ The seminiferous tubules are concerned with sperm formation. ❖ The sperm formation lasts about 2 months. EPIDIDYMIS ❖ It is 6 meter single coiled duct. ❖ It lies in the scrotum. ❖ The sperms pass through epididymis in about 2 weeks, where it starts to have its own movements. ❖ The epididymis takes a coma shape, where it has a head, body and tail. VAS DEFERENCE ❖ It is 45 cm long duct. ❖ It has a thick muscular wall which can be felt by examination. ❖ It starts as a continuation of tail of epididymis. ❖ Part of it is found in scrotum, it then passes in spermatic cord, inguinal canal and pelvis, where it ends by forming ampulla (dilatation) of the vas for sperms storage. ❖ The ampulla unites with seminal vesicle forming ejaculatory duct. SPERMATIC CORD ❖ It is a sheath formed of extensions of anterior abdominal wall. ❖ It contains the vas deference, arteries, veins, lymphatics and nerves of the testis. SEMINAL VESICLES ❖ It is a male sexual gland. ❖ It is responsible for about 70% of semen volume. ❖ The seminal vesicles secrete fructose which is the nutrient for the sperms. EJACULATORY DUCT ❖ It is formed by union of ampulla of vas and seminal vesicle. ❖ It opens in prostatic urethra. PROSTATE ❖ It is a male sexual gland. ❖ It surrounds the upper part of the urethra below the urinary bladder. ❖ It secretes its product directly in the prostatic urethra. ❖ Usually, it enlarges in old males leading to senile enlargement of prostate. BULBOURETHRAL GLANDS ❖ It is found at the sides of urethra inferior to prostate. ❖ It secretes mucoid secretion in the urethra. PENIS ❖ It is the male organ of copulation. ❖ It is formed of 3 cylindrical bodies; 2 corpora cavernosa formed of erectile tissue and a corpus spongiosum formed of spongy tissue & contains urethra. INTRODUCTION TO BODY STRUCTURE 74 Female genital system (lat view) Female genital system (ant view) Martini / McKinley & O’Loughlin INTRODUCTION TO BODY STRUCTURE 75 FEMALE GENITAL SYSTEM OVARY ❖ It is 3X2X1 cm. ❖ It lies in the pelvis. ❖ It is concerned with ova formation. UTERINE (FALLOPIAN) TUBES ❖ It is about 10 cm. ❖ It receives the ovum from the ovary, the ovum remains for 1 day for fertilization. ❖ If fertilization occurs, the cilia in the fallopian tube move the fertilized ovum to the uterus. Parts: Infundibulum: guiding the ova and showing fimbriae (finger like processes). Ampulla: dilated part. It is the site of fertilization. Isthmus: narrow part. Intrauterine part: narrowest part. UTERUS ❖ It is a hollow muscular organ 3X2X1 inches. Parts: Fundus: above the level of fallopian tubes. Body: main part. Cervix: connecting the body with the vagina. ❖ It is lined with endometrium which is the site of implantation. ❖ It is mainly supported by a transverse cervical ligament. VAGINA ❖ It is the female organ of copulation. ❖ It is a sheath which transmit the sperms to the uterus and deliver the baby. ❖ It lies post to urethra and urinary bladder and ant to anal canal and rectum. INTRODUCTION TO BODY STRUCTURE 76 Neuron Different types of neurons Marieb / Tortora & Nielsen INTRODUCTION TO BODY STRUCTURE 77 NERVOUS SYSTEM Neuron: the single unit of the nervous system is the nerve cell (neuron). It consists of: 1) The cell body: Collection of nerve cell bodies may be : a) Ganglion: outside the CNS. b) Nucleus: inside the CNS. 2) The nerve fibers: It may be: a) Dendrites: usually short, numerous & carry nerve impulses towards the cell body. b) Axon: usually single, long & carries nerve impulses away from the cell body. The collection of nerve fibers may be: a) Nerve trunk: collection of nerve fibers outside the CNS. b) Tract: collection of nerve fibers inside the CNS. Further divided into: 1) Associated: connecting different areas at the same half of CNS. 2) Commisural: connecting similar areas in the 2 halves. 3) Projecting: connecting different parts of CNS (e.g. between spinal cord & cerebrum). Synapse: a meeting between 2 neurons. Parts of nervous system: the nervous system is divided into: A) Central nervous system (CNS): protected by bones & covered with meninges containing cerebrospinal fluid (CSF). Further divided into: