An Introduction to Medical Terminology and the Human Body PDF

An introduction to Medical Terminology and the Human Body An introduction to Medical Terminology and the Human Body. 1. The chemical level...

An introduction to Medical Terminology and the Human Body An introduction to Medical Terminology and the Human Body. 1. The chemical level 6. The organism level _ The organization of the body begins at the chemical level. There are The largest level of organization is the organism level. An organism more than 100 different chemical building blocks of nature, called atoms, is any living individual. Alt the parts of the human body functions the smallest units of matter that participate im chemical reactions. together constitute the total organism {one living person). Combinations of atoms form larger chemical groupings, called molecules. Atoms include, carbon (C), hydrogen (H), oxygen (0), The human body cannot only reproduce itself (and its genetic nitrogen (IN), calcium (Ca), phosphorus’ (P). Examples of the molecules information) and maintain ongoing repair and replacement of wom or found in the body are deoxyribonucleic acid (DNA) and ghicose. damaged parts, but it can also maintain- in a constant and predictable way- an incredible number of variables required to lead liealthy, 2. The cellular level productive lives, e.g. maintaining a "normal" body temperature, fluid balance and maintaining constant blood levels of many important The molecules combine together to. form cells, the smallest (basic) chemicals and nutrients. structural and functional units of human body. Examples of cells in the human body include, epithelial cells, muscle cells and nerve cells. Table 1.1 The body systems, their principal organs (components) and Primary functions 3. The tissue level System... 2o-) Principal organs: os Primary functions Tissue is a group of many similar cells that all developed together Integumentary Skin, and structures Protection, temperature from the same part of the embryo and are all specialized to perform a system (skin and its | derived from it, such as | regulation, eliminates certain function. There are four major types of tissue; epithelial, accessory hair; nails, sweat glands |some wastes, formation of strnctures) ‘| and sebaceous glands. +vitamin D and sensation connective, muscle and nervous tissue. Skeletal system Bones, joints, cartilages |Support, protection, and ligaments - movement, mineral aud fat 4, The organ level storage and bieod cells Organs are more complex units than tissues. An organ is defined as production. a structure made up of several different kinds of tissues so arranged that Muscular system Skeletal muscles and Produces movement of the tendons | body, maintain posture together, they can perform a special function. The heart is an example of (bady position) and heat the organ level: specialized connective tissue and muscle give the heart production its shape, specialized epithelial tissue line the cavities and nervous tissues Nervous system Brain, spinal cord, Detects changes in the control contraction of cardiac muscle. The brain, heart, lungs, liver and peripheral nerves and =| external and internal kidneys are all examples of organs. special sense organs. environment of the body, generates action potential 5. The system level (nerve impulses), Sensation and memory. Systems are the most complex of the organizational units of the Endocrine system Pituitary gland, pineal { Regulation of body body. Each system involves varying mumbers and kinds of organ gland, thyroid gland, | activities by releasing arranged and they can perform compiex functions for the body. Eleven parathyroid glands, hormones, which act as major systems compose the human body: Integumentary, skeletal, thymus, adrenal glands, | chemical messengers muscular, nervous, endocrine, circulatory, lymphatic, respiratory, islets of langerhans in | transported in the blood digestive, urinary and reproductive. pancreas, ovaries and from an endocrine gland to testes. its target structure. 3A 37  An Introduction to Medical Terminology and the Human Body An Introduction to Medical Terminology and the Human Body Anatomical Terminology Pr To communicate effectively with one another, scientist and health- Cardiovascular Heart, blood vessels and | Heart act as a pump. Blood care professional use a common language of special terms when referring system blood carries oxygen and nutrients to body structures and their functions. to the cells of the body and carbon dioxide and wastes Use of such terms assumes that the body is im the anatomical position. from the cells of the body to the excretory organs. Anatomical position Lymphatic system | Lymphatic vessels, Return plasma proteins and This means that the body is standing erect, head facing forward, the lymph, lymph nodes, excess tissue fluid to the upper limbs (arms) at the sides, the palms facing forward, the feet are flat thynmus, spleen and blood, protect the body on the floor and directed forward (Figure 1.2) tonsils. from foreign antigen and Forehead (frontal) : supply the body with sail ie : Eye (orbita) immunity. HEAD {cranial Ear {ola}; (CEPHALIC) Respiratory system |Nose, pharynx, larynx, | Supply the body with Face al f Cheak (buccal) tech Nose (nasal). trachea, bronchi, oxygen, remove carbon NECK (CERVICAL) _ Mouth {oral} bronchioles, alveoli and | dioxide, maintain acid-base , Chin (mental) lungs balance and body Aaeeyy Breasibone (steral} temperature. Are Breast (mammary) {prachiall ‘ READ Digestive system Alimentary tract (mouth, | Ingestion, mechanical and Front of efvove Base of skull ICEPHALIC) pharynx, esophagus, chemical digestion of food, antecubital Forearm —~- j d : - Hip(coxa!) NECK stomach, small intestine, | absorption of nutrients and {antabrachialy 7 y ; A Groin goon —_ + (CERVICAL) 3 Angus e large intestine, rectum _j elimination. virist (capa —* a ‘Shoulder blade aud anal canal). Lo: f = (scapular) Soa Sh HN spipal column = Accessory organs bi if Palm i XY \\ (vertebral (salivary glands, Thigh (palmar). : a 4 Hand WT Back of athow {olecranal) ——o-z= 6. pancreas, liver and gall Fingers, (lamaral) * UPPER: (digital or \ Uwe bladder). phalangsal) 1. Urinary system Kidneys, ureters, urinary | Excretion of waste, fluid Antero: surface of knee I - Publs {publ} = Between hips sacral} (patellar).. bladder and urethra and electrolyte balance,. acid-base balance (cura) Reproductive system {| Male: Testes, Gonads (ovaries and testes) Buttock Ankle (gluteal) , epididymides, deferent produces gametes (ova and Font fpedal) tarsal) Back hand of ducts, spermatic cord, _| spermatozoa) that fuse Tos (digital Worm seminal vesicles together to form a new o* phalanges. ue of bs Hollow behind knee ejaculatory ducts organism, gonads also LOWER LIME! prostate gland and penis. | release hormones. ‘ {a} Anterior view an Female:. - External genitalia (vulva) - Internal genitalia (vagina, uterus, uterine {b) Posterior view Heal (calcaneet) | tubes and ovaries) ~ Mammary giands Figure L2. The anatomical position 38 39  An Intreduction to Medical Terminology and the Human Body An Introductian to Medical Terminology and the Human Body In the anatomical position, the body is upright. Two ter d (Table 1.2) Directional terms a reclining body. If the body is lying face do ie tins describe 7 e Tm 2 noe ec it is i position. Ifthe bodyis lying face up, it is in the supine Directional term Definition Example of use pine position positon , ee Superior Toward the head, or a body The thoracic cavity is Directional terms part is above another body superior to the abdominal ; Directional terms describe the location (position) of one body part cavity. part | Jnnferior Toward the feet, or a body | The liver ts inferior to the with respect to another (Figure 1.3) and (Table 1.2) part is below another body | heart part. Anterior (ventral) | Toward the front The eyes are anterior to LATERAL MEDIAL LATERAL the brain Midline SUPERIOR Posterior (dorsal) } Toward the back The esophagus is posterior vw :. to the trachea \ Esophagus (food tube) a a. os ~ - oN, 1 Medial Nearer to the midline The ulna is medial to the ~Tfachea (windplpe) (refers to an imaginary radius PROXIMAL midline dividing the body A into right and left half). A Right lung body part is medial if it is i ! i closer to this line than Sternum (breastbone) | : another part. A Lateral Away from the midline The ears are lateral to the Humerus —wi i (toward the side with eyes Tespect to the imaginary midline) intermediate Between two structures The transverse colon is intermediate between the ascending and descending colon. Proximal ‘Nearer to the attachment of | The ulna is proximal to the a limb to the trunk; nearer | carpals to the origination of a structure ‘ Distal Further from the The phalanges are distal to attachment of a limb to the | the carpals. trunk; further from the origination of a structure. Superficial Toward or sitnated near the | The epidermis is the , surface of the body superficial layer of the skin Deep Away from the surface of | The dermis is the deep Y the body (parts that are layer of the skin. INFERIOR more internal than the Figure 1.3 Directional terms. superticial parts) 40 41  An Introduction to Medical Terminology and the Human Bedy An Introduction to Medicat Terminology and the Human Body Body Regions The body as a whole can be subdivided into two major portions or components: axial and appendicular. The axial portion of the body consists of the head, neck and trunk; the appendicular portion consists of the upper and lower extremities (limbs) and their connections to the axial portion (Figure 1.2) : Q The head consists of the skull (cranial) and face (facial). The skull encloses and protects the brain, the face is the anterior (front) portion of the head that includes the eyes, nose, mouth, forehead, cheeks and chin. Q The neck supports the head and attaches it to the trunk. The tronk consists of the chest (thoracic), abdomen and pelvic. og Each upper limb attaches to the trunk and consists of the shoulder, upper arm (portion of the limb from the shoulder to the elbow), forearm (portion of the limb from the elbow to the wrist), wrist, and Median hand. Frontal plane sagittal plane Q Each lower limb also attaches to the trunk and consists of the buttock, thigh (portion of the limb from the buttock to the knee), leg (portion of the limb from the knee to the ankle), ankle, and foot. Planes of the body or body sections Observing the relative locations and organization of internal body parts requires cutting or sectioning the body along various planes (Figure Figure 1.4 Planes of the body. 1.4). The following terms describe such planes and the sections that results, 3. Transverse (horizontal) plane. This plane divides the body or any of its parts into upper and lower 1. Sagittal (median) plane (Figure 1.4) portions. Refers to a lengthwise plane that divides the body into right and left portions. Ifa sagittal plane passes along the midline aud divides the body Body cavities — into two equal parts, it is called median (midsagittal). Body cavities are spaces within the body that help protect, separate, and support internal organs. Bones, muscles, and ligaments separate the 2. Coronal (frontal) Plane various body cavities from one another. The two major cavities are the Lengthwise plane running from side to side. This plane divides the dorsal and ventral body cavities (Figure 1.5) body or any of its part into anterior and posterior (front and back) The dorsal cavity consists of the cranial and spinal cavities. The portions, cranial bones form the cranial cavity, which houses (protects) the brain. The bones of the vertebral columm form the spinal cavity (vertebral canal) which houses (protect) the spinal cord. 43 42.  An Introduction to Medical Terminology and the Human Body An Introduction to Medical Terminology and the Human Body Craniai Abdominal cavity regions cavity To describe the location of the abdomical organs, the abdominal Spinal area is subdivided into nine imaginary regions (Figure 1.6a). cavity Thoracic cavity : Pleural = seavity > Mediastinum ~ Diaphragm Abdominal “7 Gavity Abdominopelvic "cavity Pelvic cavity rn ed CF efé etn ypogasiri¢ Figure 1.5 Major body cavities. The ventral cavity consists of the thoracic or chest cavity and the (a). oN s abdominopelvic cavity. The thoracic cavity consists of a right and left pleural cavity and a midportion called the mediastinum. The right pleural cavity contains the right lung and the left pleural cavity contains the lef Ing (the only organs in the thoracic cavity that are not located in the Right hypochondriac region. mediastinum are the tings). The organs located in the mediastinum ate; the Epigastric region. PWN heart, the trachea, right and left bronchi, the esophagus, the thymus, largest Left hypochondriac region. blood vessels (thoracic aorta, superior vena cava), thoracic duct, lymph Right tumbar region. nodes and nerves. The abdominopelvic cavity consists of an upper portion, Umbilical region. the abdominal cavity, and a iower portion, the pelvic cavity. Left lumbar region. A The abdominal cavity contains the stomach, liver, gall bladder, Right iliac Gnguinal) region. intestines, kidneys, spleen, pancreas, and ureters, The pelvic cavity Hypogastric region. contains the urinary bladder, female reproductive organs (uterus, uterine Oo Left iliac (inguinal) region. tubes and ovaries), male reproductive organs (prostate gland, seminal vesicles and parts of vas deferens), sigmoid (pelvic) colon and tectum. The abdominal area may also be subdivided imto four quadrants (Figure 1.6b). 4d 45 An Introduction to Medical Terminology and the Human Body Unitahinie lis and Tissues f the Body >» Cell structure (b) » Tissues Figure 1.6 There are two common ways to subdivide the abdominal area. (a) The - Epithelial tissue abdominal area can be subdivided into nine regions The abdominal be subdivided into four quadrants. gions, (0) The & Srea may also - Connective tissue - Muscular tissue - Nervous tissue » Glandular epithelium >» Body membranes AGB AT  The Gelis and Tissues of the Body ‘The Cells and Tissues of the Body All living organism are made of celis and their products. Cells are the smallest living subunits of a multicellular organism such as a buman being. Human cells vary in size, shape, and finction. Most human cells are so small they can only be seen with the aid of a microscope and are measured in units called microns (imicron= 0.002 mm ). With respect to shape, human cells vary greatly. Some are round or spherical, others rectangular, still others irregular, white blood cells even change shape as they move. The human body develops from a single cell called the zygote, which results from the fusion of the ovum and the spermatozoon (male germ cell). Cell multiplication follows and, as the fetus grows, cells with different structural and functional specialization develop, alt with the same genetic make-up as the zygote. Cell structure Each cell is surrounded by a plasma membrane that separates the cell from its surrounding environment. The inside of the cell is composed largely of a gel-like substance called cytoplasm. The cytoplasm is made of various organelles suspended in a watery fluid called cytosol, or sometimes, intracellular fluid. The nucleus, which is not a part of the cytoplasm, is at the center of the cell. Thus, the main cell structures are (Figure 2.1): * The cell membrane (plasma membrane). * The cytoplasm, including the organelles. * The nucleus. / Red blood cells (erythrocytes} are an exception because they have no nuclei when mature. 49  The Gells and Tissues of the Body The Cells and Tissues of the Body The phospholipids permit lipid soluble materials to easily enter or leave the cell by diffusion through the cell membrane. The presence of Nuclear envelope cholesterol decreases the fluidity of the membrane thus making it more 7m Nucleslus | Nucleus stable (without cholesterol, cell membrane would break far too easily). Extracellular side of membrane Lysosome Carbohydrate Fibrous proteins Tibosome ; 7 f - ~ Lysosome Rough ; ; ei " *fusing , with endoplasmic ~~ an : Jeticulum 7 Double _jayer.of P phospholipid ieie molecules apparatus Secretory Cholesterol’ | Glabular vesicles moleculés - protein “| ‘fatty acid woe "tall" si Cytoplasmicic side Hydrophilic phosphate of membrane *headl" Cilia Miorovili Figure 2.2 Celi membrane Figure 2.i Cell structure The proteins have several fictions: Some form "pores" or openings to permit passage of materials; Cell membrane others are "enzymes" that also help substances enter the cell. Stili other proteins, with oligosaccharides on their outer surface, are "antigens", The cell membrane also called plasma membrane (Figure 2.2) markers that identify the cells of an individual as "self. Yet another consists of two layers of phospholipids, proteins, and other molecules, group of proteins serves as "receptor sites for hormones". e.g. cholestrol. certain The cell membrane is selectively permeable, that is, The phospholipid molecules have "heads" (water soluble) which is substances are permitted to pass through and others are not. electrically charged and hydrophilic (water loving) and double "tails" (lipid soluble), which has no charge and is considered as hydrophobic Cytoplasm and cell organelles ; (water fearing or hating). The water soluble phosphate "heads" form the Cytoplasm is a watery solution of minerals, gases, and organic.. surface of the membrane and the lipid soluble phosphate "tails" make up molecules that is found between the nucleus and the cell membrane the cytoplas m and many of the cell the interior of the membrane. Chemical reactions takes place within organelles are found here. 30 St  The Cells and Tissues of the Body The Cells and Tissues of the Body The cell organelles found within the cytoplasm are (Figure 2. 1): other material, e.g. protein in the form of glycoprotein, for secretion from * Mitochondria.. the cell. « Ribosomes. : ' Fo secrete a substance, small sacs of the Golgi membrane break off * Endoplasmic reticulum. and fise with the cell membrane, releasing the substances to the exterior * Golgi apparatus. of the cell. * Lysosomes. * Centrosome and centrioles. Lysosomes: : + Micrefilaments and microtubules. Lysosomes are tiny (single) sacs within the cytoplasm that contain * Cilla and flagella. digestive enzymes. * Vesicles. « Peroxisomes. Peroxisomes Peroxisomes are membranous sacs which are abundant in kidney Mitochondria aud liver cells. They contain enzymes that catalyze (speed) a variety of Mitochondria are oval or spherical organelles within the cytoplasm, biochemical reactions, including the synthesis of bile acids, and bounded by a double membrane. The inner membrane has folds called detoxification of materials, e.g. hydrogen peroxide and alcohol. cristae. Connected to the cristae are enzymes that control some of the chemical reactions that release energy ftom certain mutrient molecules. Centrosome and centrioles - Mitochondria are the major sites of chemical reactions, aerobic (oxygen. The centrosome is a specialized structure near the nucleus, where tequiring) reactions that transform this energy into adenosine microtubules formation occurs, It contains two centrioles, which are triphosphate (ATP), a chemical form the cell can use. Mitochondria are normally oriented perpendicular to each other. Each centriole is a small, the site of ATP production (the power house of the cell), Muscle cells cylindrical organelle composed of nine triplets, each triplet consists of (fibers) have many mitochondria to meet there need for energy. three parallel microtubules jomed together. During mitosis, they distribute chromosomes'to newly forming cells. Ribosomes All ribosomes are tiny granules composed of protein and RNA Microfitaments and microtubules |. molecules. Ribosomes are the site of protein synthesis. Many ribosomes Microfilaments are tiny rods of actin protein that form meshwork are attached to endoplasmic reticulum membranes, others are scattered or bundless. They provide structural, support, maintain the characteristic shape of the cell, and provide movement. In muscle cells, microfilaments throughout the cytoplasm. Clusters of ribosomes in the cytoplasm called aggregate to form myofibrils, which help these cells to contract. polysomes. Microtubules are long, slender tubes, composed of molecules of a Endoplasmic reticulum globular protem called tubulin. They are involved in the movement of the Endoplasmic reticulum (ER) cell, and of organelles within the cell, the movement of cilia. is an extensive network of membranous tubules. that extend from the nuclear membrane to the cell membrane. There are two types: smooth and rough. Rough ER has Cilia and flagella numerous ribosomes on its surface, They are motile thread-like projections through the cell membrane. where as smooth ER has no tibosomes at all. Cilia serve the function of sweeping materials across the cell surface. They are usually shorter than flagella, and an individual cells has many - Golgi apparatus of them, e.g. cells lining the uterine tubes have cilia to propel (sweep) the Golgi apparatus is a series.of flat membranous sacs. Carbohydrates ovum toward the uterus. are synthesized within the Golgi apparatus, and are packaged, along with A flagellum is found only in the sperm cell which provide motility or movement for them. - 5? 53  The Cells and Tissues of the Body The Cells and Tissues of the Body Vesicles Tissues Vesicles (vacuoles) are membranous sacs formed by part of the cell A tissue is 4 group of cells with similar structure and function, the membrane folding inward and pinching off. Vesicles containing some tissues of the body are classified according to the shape, size and liquid or solid material. functions of these cells. There are four major types of tissues in the body, Nucleus each of which has subdivisions. 1- Epithelial tissue or epithelium. Nucleus is a large spherical structure located at the center of the cell 2+ Connective tissue. and is bounded by a double-layered nuclear membrane with many pores 3- Muscle tissue. called nuclear pores. The nucleus contains a fluid, called nucleoplasm, in 4- Nervous tissue. which the following structures are suspended: nucleolus and chromatin. Epithelial tissue (Figure 2.4) Nucleolus is a small sphere made of DNA, RNA and protein. The Epithelial tissues are found on surfaces as either coverings (outer nucleoli form a type of RNA called ribosomal RNA, which becomes part surface) or lining (inner surfaces). Epithelial tissue have no capillaries of ofribosomes and is involved in protein synthesis. their own, they receive oxygen and nutrients from the connective tissue Chromatin beneath them. The nucleus is the control center of the cell because it contains the Epithelial tissue may be: chromosomes. The 46 chromosomes of a human cell are usually not - Simple: a single layer of cells. visible; they are long threads called chromatin. When a cell divides, - Stratified: several layers of cells. however, the chromatin coils extensively into visible chromosomes. GELL SHAPES: SIMPLE STRATIFIED (Figure 2,3) ay tis. Chromosomes are made of DNA and jog Squamaus protein. The molecule of DNA is a sequence of nucleotide molecules (proteins) joined by phosphate-sugar molecules. Each nucleotide contains one of the following four substances called bases: Adenine (A), Thiamine (T), Guanine (G) and cytosine (C). The bases occur in a set pattern; A in one chain is paired with T in the other and G with C. In this way the nucleotides are Simple P columnal) atranged in a precisely ordered manner in (Transitional, relaxed} which one cham is complementary to the other. DNA is the genetic code for the Cita ail characteristics and activities of the cell. The DNA in the nucleus of each cell contain all Nuctous — es of the genetic information for all human c F calls (Translttonal, stretched) traits. Figure 2.3 Structure of a Ciliated columnar epithelium. Chromosome Figure 2.4 Epithelial tissue 54  The Gelis and Tissues of the Body The Cells and Tissues of the Body Simple epithelium (Figure 2.4) at the surface are mostly flat cells. Mitosis takes place in the lowest layers to ; Simple epithelium consists of a single layer of identical cells and is continually produce new celis to replace those worn off at the surface. divided into three types according to the shape of cells, which differs according to their functions. Simple epithelium found on secretory and. There are two main types of stratified squamous epithehum: absorptive surfaces. Keratinised and Non-keratinised. Keratinised stratified squamous epithbelium 1. Simple squamous epithelium Simple squamous epithelium consists of a single layer of thin, This type of tissue found on dry surfaces that are subjected to wear flattened cells. These cells fit tightly together, somewhat like floor tiles. and tear, Le. skin, hair and nails. Simple squamous epithelium is common at sides of diffusion and filtration, ’ Non-keratinised stratified squamous epithelium Simple squamous epithelium found lining the following structures: This type of tissue found on wet surfaces that may be subjected to wear and tear, ie. the inner lining of mouth, pharynx, esophagus, Heart, blood vessels, lymph vessels and alveoli of lungs. vagina and the conjunctiva of the eyes. 2, Simple cuboidal (cubical) epithelium Transitional epithelium _ Simple cuboidal epithelium is a single layer of cube-shaped cells. Transitional epithelmm is a type of stratified epithelium in which This type of cell makes up the functional unit of thyroid gland and the surface cells change shape from round to squamous. This type of salivary glands, also forms the tubules of kidney. tissue is found linmg the urinary bladder. When the urinary bladder is empty the surface cells are rounded (Figure 2.4), When the urmary 3. Simple columnar epithelium bladder fills, these cells become squamous (flattened). Transitional epithelium allows for stretching as the bladder fills. The ceils of this tissue can be ciliated or nonciliated. Nonciliated simple columnar epithelium formed by a single layer of columnar Glandular epithelium (rectangular)-shaped cells. This type of tissue is specialized for secretion The glandular epithelium produces secretion,which is accomplished and absorption. It is found lining most of the alimentary tract (stomach, by glandular cells lie in clusters deep to the covermg and linmg small and large intestine). epithelium. A gland may consist of a single ceil (unicellular glands) or a Ciliated simple columnar epithelium consist of columnar cells group of cells (multicellular glands). - that have cilia on their free surfaces and it is found lining the uterine All the glands in the body can be classified as either exocrine or tubes and most of the respiratory passages. endocrine glands. Exocrine glands charge their secretion products into ducts, the Stratified epithelium _ typical example of exocrine glands is the salivary glands. The saliva is Stratified epithelium consist of several layers of cells of various produced in the gland and then discharged into a duct that transport it to shapes (Figure 2.4). The superficial layers grow up from below. the mouth. The secretion of exocrine glands include sweat, mucus, saliva, _ _ The main fimotion of stratified epithelium is to protect the sebum (oil), ear wax (cerumen), and digestive enzymes. underlying structures from mechanical wear and tear. Stratified epithelium is divided into two main types: stratified Endocrine glands called duciless glands because they discharge their squamous and transitional. secretion products (hormones) directly into the blood or interstitial fluid. The pituitary, thyroid and adrenal glands are examples of endocrine glands. Stratified squamous epithelium Structural classification of exocrine glands. _ Stratified squamous epithelium consists of many layers of cells of Exocrine glands are classified as unicellular and multicellular different shapes. The cells in the deepest layer are mainly columnar and those glands. Unicellular glands consist of a single cell, such as goblet cells SA sy —  The Celis and Tissues of the Body The Calls and Tissues of the Body which secrete mucus directly onto the surface of a lining epithelium Functional classification of exocrine glands (Figure 2.5) rather than into ducts. The functional classification of exocrine glands is based on how Multicellular exocrine glands are classified according to two their secretion is released from the cell According to these functional criteria; the shape and complexity (branching) of their ducts and by the criteria, there are three types of exocrine glands: shape of the secretory portion of the gland. Shapes include tubular and 1. Apocrine. alveolar (sac-like). Simple exocrine glands have only one duct leading to 2. Holocrine. the surface, and compound exocrine glands have two or more ducts 3. Merocrine. (Fable 2.1). Apocrine glands. Collect their secretory products near the apex, or Table 2,1 Structural classificati tip, of the secretory cells. Then that portion of the cell pinches off from Co the rest of the cell to release the secretion into duct. This process results in some loss of cytoplasm and damage to the cell. Tubular (single, es ‘i Intestinal Recovery and repair of the cells are very rapid and continued secretion occurs. Apocrine glands are the mammary glands and sweat straight) Simple Simple tubular glands Tubular (coiled) Simple Simple colled sweat glands : : Gasiric Tubular (multiple) Simple Simple branched tubular (stomach) glands Sebaceous Alveolar (single) Simple Sumpie alveolar (skin oil) glands ‘al Apocrine gland Holocrine gland Merocrine gland :. Simple branched = Sebaceous Alveolar (multiple) Simple alveolar glands Figure 2.5 Three types of exocrine glands. Here exocrine glands are classified by - method of secretion. Tubular (multiple) Compound Compound tubular wands Holocrine glands. The cells collect their secretory product (sebum or oil) inside the cell and then the cell rupture completely to release it.. Compound. Mammary Examples of holocrine glands are the sebaceous glands. Alveolar (multiple) Compound alveolar glands Merocrine glands. Discharge their secretion directly through the cell or plasma memibrane. The discharged process is completed without Some tubular; some Compound. _loss of the cytoplasm and without injury to the cell (plasma) membrane. alveolar Compound tubuloalveolar Salivary glands Most exocrine glands of the body are merocrine glands. Examples are the salivary glands and pancreas. 57  The Celis and Tissues of the Body The Cells and Tissues of the Body Connective tissue They secrete specific antibodies into the blood in response to the Connective tissue bind (comect) structures, provide support and. presence of foreign material, such as microbes. : protection, serve as frameworks, fill Spaces, store fat, produce blood cells, protect against infections, and help repair tissue damage. Mast cells These cells are similar to bosophils leukocytes. Connective tissue cells are widely separated from each other than epithelial cells and they have an abundance of extracellular matrix They are found under the fibruous capsule of some organs, e.g. liver between them. The matrix consists of fibers and a.ground substance and spleen and in considerable numbers round blood vessels. whose consistency varies from fluid to semisolid to soild. They produce heparin, serotonin (5-hydroxytryptamine) and. Connective tissue cells have the ability to divide. Connective tissne histamme which are released when the cells are damaged by disease or have good blood supply, and are well nourished. injury. Histamine and serotonin are involved in local and general Connective tissue cells inflammatory reactions, and may be associated with the development of The different types of cells involved inciude:, allergies and hypersensitivity. Heparin prevents coagulation of plasma Fibroblasts. which may aid the passage of protective substances from blood to * Macrophages. affected tissue. * Mast cells. Fat (adipocytes) cells oe * Plasma celis, These cells occur’singly or in groups, especially in adipose tissue * Fat celis. under the skin. They vary in size and shape according to the amounts of fat they contain. : Fibroblasts These are large, star-shaped cells, produce fibers by. secreting Connective tissue fibers proteins into the extracellular thatrix of comective tissues. The fibers There are three types of connective tissue fibers. They are: they produce are collagen fibers (the basic material of fbrous ‘tissue). + Collagenous fibers. They also produce elastic fibers. In some glands a type of fibroblast * Elastic fibers. called reticular cells produce fine fibrous strands called reticulin and are * Reticular fibers. closely associated with phagocytosis.. Collagenous fibers. Are thick threads of protein collagen. They are Macrophages flexible but slightly elastic, they have greate tensile. strength. Found in These cells are irregular in shape, they contain granules in the body parts that hold structures together, such as ligaments (which cytoplasm. Some of the macrophages are fixed, i.e. attached to connective connect bones to bones) and tendons (which connect muscles to bones). tissue’ fibers, and the others are motile. They are actively phagocytic, engulfing and digesting cell debris, bacteria and other foreign bodies. Connective tissue which contain large amounts of collagenous fibers called dense connective tissue, and appears white, for this reason, Macrophages cells include: monocytes in blood, phagocytes in the alveoli collagenous fibers are some times called white fibers. of the hmgs, Aupyfer cells in the liver sinusoids, Fibroblasts in the lymph nodes and spleen, osteocytes in the bones and inicroglial cells in the brain. Elastic fibers: Are composed. of a protein called elastin. Elastic fibers: are weaker than collagenous fibers, but they stretch easily and Plasma cells return to its original shapes ‘and lengths. Elastic fibers called yellow : : -Plasma cells are derived from B-Lymphocytes. fibers, because tissues contain elastic fibers appear yeHlowish. 6D gt  The Cells and Tissues of the Body The Cells and Tissues of the Body Reticular fibers. Are very thin collagenous fiber. They are branched White adipose tissue, forms about 20 to 25% of body weight in aud form supporting network in a variety of organs, such as spleen and adult person, and supports the following structures: lymph nodes. + Subcutaneous layer under the skin. « Around heart, kidneys Types of connective tissue and eyes. eT Ot. : ; tH Nucleus There are six types of connective tissue: * Between muscle fibers. LLa ar me wo * Loose comnective tissue. * Cartilage. < 3 - ae * Dense connective tissue, * Bone. Brown adipose tissue, |x: wt ao hy. — adipocyte * Blood. * Lymphatic tissue. the dark colour obtained from % Lowe Sere | fatoaly ~ 1. Loose connective tissue This type of connective tissue contain fibers which are loosely a very rich blood * supply and numerous which mitochondria, contain. coloured cx |, |-, > wd ~, IS & “or 4 Ba r 7 oe, ad ~ Asie r twisted and the cells are numerous. There are three types of loose pigment that participate in Saomet comnective tissue: aerobic cellular respiration. Figure 2.7 Adipose tissue * Areolar tissue. Brown adipose tissue * Adipose tissue. generates considerable beat and probably helps to maintain body * Reticular tissue. temperature in the newborn. Brown adipose tissue widespread in the fetus and infant, in adults only small amounts are present in the following | Areolar connective tissue locations: This is the most peneralized of all * Between the scapulae. connective tissue in the body. The * Inthe nape ofsieck. ceils of this type of tissue includes * Inthe wall of large blood vessels of the trunk. fibroblasts, macrophages and Reticular connective tissue. adipocytes. The fibers present are: Reticular connective tissue consists of reticular cells and fine collagen, elastic and reticular interlacing reticular fibers. , fibers. Areolar connective tissue supports and connects the Reticular connective tissue forms the stroma (supportmg following structures: framework) of the spleen, lymph nodes and liver. * Blood vessels and nerves. In addition, reticular fibers in the spleen filter blood and remove tissue. ¢ Between muscles. worn-out blood cells and reticular fibers in lymph nodes filter lymph and * In the subcutaneous layer (under the skin). remove bacteria. * In the wall of alimentary canal. Supporting secretory cells of the glands. 2- Dense connective tissue Dense connective tissue contains more numerous, thicker and Adipose tissue denser fibers but fewer cells as compared with loose connective tissue. The cells of adipose tissue called fat cells (adipocytes), they are The dense connective tissue includes fibrous tissue and elastic tissue. specialized for the storage of fat globules (triglycerides). Adipose tissue is found wherever areolar connective tissue is located. Adipose tissue is a Fibrous tissue good insulator and can therefore reduce heat loss through the skin. It is a Fibrous tissue is made up of closely packed bundless of collagen major energy reserve and generally supports and protects many fibers. Fibrocytes (old and inactive fibroblasts} are few in number lying structures. There are two types of adipose tissue: White and brown, in rows between the bundles of fibers. 62 2,  The Geils and Tissues of the Bady The Cells and Tissues of the Body 3- Cartilage. Cartilage consists of a dense network of collagen and elastic fibers, the cartilage cells are cailed chondrocytes and are few in number. There are three types of cartilage: =\.collagen fibres - Hyalme cartilage. - Fibrocartilage. ¢ Elastic cartilage. = SC & Gop --Fibrocyte Hyaline cartilage Figure 2.8 Fibrous tissue Hyaline cartilage appears in. the body as a bluish Examples of fibrous tissue includes: white, shiny and smooth aI Chandrocytes * Ligaments, which bind bones together. ce] tissue. Hyaline cartilage * Periosteum (the outer protective covering of bones). S Cell nest is the most abundant * Muscle sheath (nmsele fascia) and tendons that attaches the muscle to cartilage in the body. rao Solid matrix bone. Example of hyalme * The outer protective covering of some organs, e.g. the brain, kidneys cartilage includes: and the lymph nodes. » Articular cartilages (on the surface of the Elastic tissue Figure 2.10 Hyaline cartilage parts of bones forming the joints). Costal cartilages (attach ribs to sternum). * Forming part of some respiratory organs (larynx, trachea and bronchi). Hyaline cartilage is the weakest of the three types of cartilage. Fibrocartilage. Elastic fibres Fibrocartilage consists of bundless of collagen fibers. It is a strong, rigid and slightly flexible tissue. Figure 2.9 Elastic tissue Elastic tissue is made up of masses of branching elastic fibers. Fibroblasts are few in number present in spaces between the fibers. Elastic connective tissue is quite strong and can recoil to its original shape after being stretched (capable of considerable extension and recoil). ?”\_ chondrocyte Elastic tissue found in the wall of e Lungs. ® Large arteries. ® Epiplottis. ° Outer ear. « fi Figure 2.11 Fibrocartilage 64 As  The Celis and Tissues of the Body The Cells and Tissues of the Body _ Lacunae ate tiny spaces between lamellae contain mature bone cells Examples of fibrocartilage includes: * The intervertebral discs (pads between the bodies of the vertebrae called osteocytes. of the vertebral column). 3. Canaliculi are networks of minute canals link the lacunae with each ¢ The semilunar cartilages (between the articulating surfaces of the other and with the central haversian canal. Canaliculi provide routes bones of the knee joint). for nutrients to reach osteocytes and for wastes to leave them. 4, Central baversian canal, containing blood and lymph vessels and Elastic cartilage nerves. Elastic cartilage provides strength and elasticity (flexibility) and maintains the shape of certain structures, such as: : é a2 7 c * Pinna or lobe of the ear. Endosteurm—!. Panel * The epiglottis. =. SS Periostoum, CER Ke COPE WA) a i Nerve b 6 Blood = vessels Nerve ( RANA ey uy Me Gs) bn J d 1 Central Compact ——} wed i aa canal a P AB20 Ae fone 13 ; Blood OaA vessels Be Chondrocytes 9o' foc) algoa A onea ee PaesoT we PES: TDL Figure 2.12 Elastic cartilage 4- Bone Bones are organs composed of several different connective tissue, including bone (osseous) tissue, the periosteum, red and yellow bone matrow and the endosteum (a membrane that lines a space within bone (space) that stores yellow bone marrow). The bone cells called osteocytes located Figure 2.13 Compact bone in very small bony chambers called lacunae. There are two types of bone tissue, compact and spongy (cancellous) bone tissue. Spongy (cancellous) bone Compact bone To the naked eye, spongy bone locks like a honey-comb. The essential unit of compact bone is an osteon or haversian Microscopic examination reveals a framework (colunms} of bone called system. Each osteon has four parts (Figure 2.13): trabeculae (little beams), which consist of a few lamellae, osteocytes and. 1. The lamellae are concentric plates or rings of matrix that consist of lac