Human Tissue I&II - Dr Hisham - Fall 2024.pdf

MEDI 101 Body tissue 1 Dr Hisham Alshaikhli M.B.Ch.B, M.Sc, Ph.D, PGCertMedTech-NZ Assistant Professor College of Nursing – Qatar University [email protected] Office hours: Wednesday 12 pm-1 pm – Building...

MEDI 101 Body tissue 1 Dr Hisham Alshaikhli M.B.Ch.B, M.Sc, Ph.D, PGCertMedTech-NZ Assistant Professor College of Nursing – Qatar University [email protected] Office hours: Wednesday 12 pm-1 pm – Building I03 – Office 504 1 Learning objectives Body Tissues and membranes Epithelial tissue Classification of epithelial tissues. Glandular tissues Classification of glandular tissues. Classification of connective tissues Bone and cartilage Muscle tissue Nervous tissue Classification of tissue membranes 2 Body Tissues Tissues Groups of cells with similar structure and function Four primary types: 1. Epithelial tissue (epithelium) 2. Connective tissue 3. Muscle tissue 4. Nervous tissue 3 Epithelial Tissue Locations: Body coverings Body linings Glandular tissue Functions: Protection Absorption Filtration Secretion 4 Epithelial Tissue Hallmarks of epithelial tissues: Cover and line body surfaces Often form sheets with one free surface, the apical surface, and an anchored surface, the basement membrane Avascular (no blood supply) Regenerate easily if well nourished Classification of epithelia Number of cell layers Simple—one layer Stratified—more than one layer Shape of cells Squamous—flattened, like fish scales Cuboidal—cube-shaped, like dice 5 Columnar—shaped like columns  Classification and functions of epithelia. Apical surface Basal Simple surface Apical surface Basal surface Stratified (a) Classification based on number of cell layers © 2018 Pearson Education, Ltd.  Classification and functions of epithelia. © 2018 Pearson Education, Ltd.  Epithelial Tissue Simple epithelia Functions in absorption, secretion, and filtration Very thin (so not suited for protection) Simple squamous epithelium Single layer in membranesof flat cells Locations—usually forms membranes Lines air sacs of the lungs Forms walls of capillaries Forms serous membranes (serosae) that line and cover organs in ventral cavity Functions in diffusion, filtration, or secretion 8 Epithelial Tissue Simple cuboidal epithelium A single layer of cubelike cells Locations Common in glands and their ducts Forms walls of kidney tubules Covers the surface of ovaries Functions in secretion and absorption; ciliated types propel mucus or reproductive cells 9  Epithelial Tissue Simple columnar epithelium Single layer of tall cells Goblet cells secrete mucus Locations Lining of the digestive tract from stomach to anus Mucous membranes (mucosae) line body cavities opening to the exterior Functions in secretion and absorption; ciliated types propel mucus or reproductive cells 10 Epithelial Tissue Pseudostratified columnar epithelium All cells rest on a basement membrane Single layer, but some cells are shorter than others giving a false (pseudo) impression of stratification Location: respiratory tract, where it is ciliated and known as pseudostratified ciliated columnar epithelium Functions in absorption or secretion 11 Epithelial Tissue Stratified epithelia Consist of two or more cell layers Function primarily in protection Stratified squamous epithelium Most common stratified epithelium Named for cells present at the free (apical) surface, which are squamous Functions as a protective covering where friction is common Locations—lining of the: Skin (outer portion) Mouth Esophagus 12 Epithelial Tissue Stratified cuboidal epithelium —two layers of cuboidal cells; functions in protection Stratified columnar epithelium —surface cells are columnar, and cells underneath vary in size and shape; functions in protection Stratified cuboidal and columnar Rare in human body Found mainly in ducts of large glands 13 Epithelial Tissue Transitional epithelium Composed of modified stratified squamous epithelium Shape of cells depends upon the amount of stretching Functions in stretching and the ability to return to normal shape Location: lining of urinary system organs 14 Epithelial Tissue Glandular epithelia One or more cells responsible for secreting a particular product Secretions contain protein molecules in an aqueous (water-based) fluid Secretion is an active process Two major gland types develop from epithelial sheets Endocrine glands Ductless; secretions (hormones) diffuse into blood vessels Examples include thyroid, adrenals, and pituitary Exocrine glands Secretions empty through ducts to the epithelial surface Include sweat and oil glands, liver, and pancreas (both internal and external) 15  Exocrine Glands Ducts carry products of exocrine glands to epithelial surface Include the following diverse glands: Mucus-secreting glands Sweat and oil glands Salivary glands Liver and pancreas 16  Endocrine Glands Ductless glands Secrete substances directly into bloodstream Produce molecules called hormones Examples: pituitary, adrenal, thyroid, parathyroid, pancreas, gonads, thymus, pineal etc. 17 Connective Tissue Found everywhere in the body to connect body parts Includes the most abundant and widely distributed tissues Functions Protection Support Binding Characteristics of connective tissue Variations in blood supply Some tissue types are well vascularized Some have a poor blood supply or are avascular Extracellular matrix Nonliving material that surrounds living cells 18 Connective Tissue Two main elements of the extracellular matrix 1. Ground substance —mostly water, along with adhesion proteins and polysaccharide molecules 2. Fibers Collagen (white) fibers Elastic (yellow) fibers Reticular fibers (a type of collagen) 19 Connective Tissue Types of connective tissue from most rigid to softest, or most fluid: A. Bone B. Cartilage C. Dense connective tissue D. Loose connective tissue E. Blood 20 Connective Tissue A. Bone (osseous tissue) Composed of: Osteocytes (bone cells) sitting in lacunae (cavities) Hard matrix of calcium salts Large numbers of collagen fibers Functions to protect and support the body 21 Connective Tissue B. Cartilage Less hard and more flexible than bone Found in only a few places in the body Chondrocyte (cartilage cell) is the major cell type Types a. Hyaline cartilage b. Elastic cartilage c. Fibrocartilage 22  MEDI 101 Body tissue 2 Dr Hisham Alshaikhli M.B.Ch.B, M.Sc, Ph.D, PGCertMedTech-NZ Assistant Professor College of Nursing – Qatar University [email protected] Office hours: Wednesday 12 pm-1 pm – Building I03 – Office 504 1 23 B. Cartilage a. Hyaline cartilage Most widespread type of cartilage Abundant collagen fibers hidden by a glassy, rubbery matrix Locations Trachea Attaches ribs to the breastbone Covers ends of long bones Entire fetal skeleton prior to birth Epiphyseal (growth) plates in long bones 24 B. Cartilage b. Elastic cartilage (not pictured) Provides elasticity Location: supports the external ear c. Fibrocartilage Highly compressible Location: forms cushion-like discs between vertebrae of the spinal column 25 Connective Tissue C. Dense connective tissue (dense fibrous tissue) Main matrix element is collagen fiber Fibroblasts are cells that make fibers Locations Tendons —attach skeletal muscle to bone Ligaments —attach bone to bone at joints and are more elastic than tendons Dermis —lower layers of the skin 26 Connective Tissue D. Loose connective tissue Softer, have more cells and fewer fibers than other connective tissues (except blood) Types 1. Areolar 2. Adipose 3. Reticular 27 D. Loose connective tissue 1. Areolar connective tissue Most widely distributed connective tissue Soft, pliable tissue like “cobwebs” Functions as a universal packing tissue and “glue” to hold organs in place Layer of areolar tissue called lamina propria underlies all membranes All fiber types form a loose network Can soak up excess fluid (causes edema) 28  D. Loose connective tissue 2. Adipose connective tissue An areolar tissue in which adipose (fat) cells dominate Functions Insulates the body Protects some organs Serves as a site of fuel storage Locations Subcutaneous tissue beneath the skin Protects organs, such as the kidneys Fat “depots” include hips, breasts, and belly 29 D. Loose connective tissue 3. Reticular connective tissue A delicate network of interwoven fibers with reticular cells (like fibroblasts) Forms stroma (internal framework) of organs Locations Lymph nodes Spleen Bone marrow 30 Connective Tissue E. Blood (vascular tissue) Blood cells are surrounded by a fluid matrix known as blood plasma Soluble fibers are visible only during the clotting Functions as the transport vehicle for the cardiovascular system, carrying: Nutrients Wastes Respiratory gases 31  Dr Hisham Alshaikhli M.B.Ch.B, M.Sc, Ph.D, PGCertMedTech-NZ Assistant Professor College of Nursing – Qatar University [email protected] Office hours: Mondays 12 pm-1 pm – Building I03 – Office 504  MEDI 101 Body tissue 2 Dr Hisham Alshaikhli M.B.Ch.B, M.Sc, Ph.D, PGCertMedTech-NZ Assistant Professor College of Nursing – Qatar University [email protected] Office hours: Wednesday 12 pm-1 pm – Building I03 – Office 504 1 33 Muscle Tissue Function is to contract, or shorten, to produce movement Three types of muscle tissue 1. Skeletal 2. Cardiac 3. Smooth 34 Muscle Tissue 1. Skeletal muscle tissue Packaged by connective tissue sheets into skeletal muscles, which are attached to the skeleton and pull on bones or skin Voluntarily (consciously) controlled Produces gross body movements or facial expressions Characteristics of skeletal muscle cells Striations (stripes) Multinucleate (more than one nucleus) Long, cylindrical shape 35 Muscle Tissue 2. Cardiac muscle tissue Involuntarily controlled Found only in the heart Pumps blood through blood vessels Characteristics of cardiac muscle cells Striations One nucleus per cell Short, branching cells Intercalated discs contain gap junctions to connect cells together 36 Muscle Tissue 3. Smooth (visceral) muscle tissue Involuntarily controlled Found in walls of hollow organs such as stomach, uterus, and blood vessels Peristalsis, a wavelike activity, is a typical activity Characteristics of smooth muscle cells No visible striations One nucleus per cell Spindle-shaped cells 37 Nervous Tissue: Structure and Function Nervous tissue is made up of two principal cell types Neurons Supporting cells (called neuroglia, or glial cells, or glia) Resemble neurons Unable to conduct nerve impulses Never lose the ability to divide © 2018 Pearson Education, Ltd. Nervous Tissue Function is to receive and conduct electrochemical impulses to and from body parts Irritability Conductivity Composed of neurons and nerve support cells 39  NEUROGLIA (Supporting Cells) Support cells called neuroglia, or glial cells, or glia Functions: Insulate, support and protect neurons Resemble neurons Unable to conduct nerve impulses Never lose the ability to divide Neuroglia are classified into five types: 1) Astrocytes 2) Oligodendrocytes – Myeline of CNS 3) Microglia 4) Ependyma 5) Schwan cells – Myeline of peripheral NS Astrocytes Abundant, star-shaped cells Brace and anchor neurons to blood capillaries Determine permeability and exchanges between blood capillaries and neurons Protect neurons from harmful substances in blood Control the chemical environment of the brain Microglia Spiderlike phagocytes Monitor health of nearby neurons Dispose of debris CNS glial cells: ependymal cells Line cavities of the brain and spinal cord Cilia assist with circulation of cerebrospinal fluid © 2018 Pearson Education, Ltd. Oligodendrocytes Wrap around nerve fibers in the central nervous system Produce myelin sheaths Schwann cells Form myelin sheath around nerve fibers in the PNS Satellite cells Protect and cushion neuron cell bodies Neurons Neurons = nerve cells Cells specialized to transmit messages (nerve impulses) Major regions of all neurons Cell body—nucleus and metabolic center of the cell Processes—fibers that extend from the cell body Cell body is the metabolic center of the neuron Nucleus with large nucleolus Nissl bodies Rough endoplasmic reticulum Neurofibrils Intermediate filaments that maintain cell shape  Processes (fibers) Dendrites—conduct impulses toward the cell body Neurons may have hundreds of dendrites Axons—conduct impulses away from the cell body Neurons have only one axon arising from the cell body at the axon hillock End in axon terminals, which contain vesicles with neurotransmitters Axon terminals are separated from the next neuron by a gap Synaptic cleft—gap between axon terminals and the next neuron Synapse—functional junction between nerves where a nerve impulse is transmitted  Nervous Tissue: Neurons Myelin White, fatty material covering axons Protects and insulates fibers Speeds nerve impulse transmission Myelin sheaths Schwann cells—wrap axons in a jelly roll–like fashion (PNS) to form the myelin sheath Neurilemma—part of the Schwann cell external to the myelin sheath Nodes of Ranvier—gaps in myelin sheath along the axon Oligodendrocytes—produce myelin sheaths around axons of the CNS Lack a neurilemma  Body Membranes Functions of body membranes Cover body surfaces Line body cavities Form protective sheets around organs Classified according to tissue types © 2018 Pearson Education, Ltd.  Body Membranes Epithelial membranes 1. Cutaneous membranes 2. Mucous membranes 3. Serous membranes Connective tissue membranes Synovial membranes © 2018 Pearson Education, Ltd. Epithelial Membranes Epithelial membranes are simple organs Also called covering and lining membranes These membranes contain: Epithelial tissue layer Connective tissue layer 1. Cutaneous membrane = skin Dry membrane Outermost protective boundary Construction Epidermis is composed of keratinized stratified squamous epithelium Dermis is mostly dense (fibrous) connective tissue © 2018 Pearson Education, Ltd.  Epithelial Membranes 2. Mucous membranes (mucosae) Moist membranes Line all body cavities that open to the exterior body surface Adapted for absorption or secretion Construction Epithelium type depends on site Loose connective tissue (lamina propria) 3. Serous membranes (serosae) Line open body cavities that are closed to the exterior of the body Occur in pairs, separated by serous fluid, with a visceral and parietal layer Construction Simple squamous epithelium Areolar connective tissue Figure 4.1d Classes of epithelial membranes. Outer balloon wall (comparable to parietal serosa) Air (comparable to serous cavity) Inner balloon wall (comparable to visceral serosa) (d) A fist thrust into a limp balloon demonstrates the relationship between the parietal and visceral serous membrane layers. © 2018 Pearson Education, Ltd.  Epithelial Membranes Specific serous membranes a. Pericardium Around the heart b. Pleura Around the lungs c. Peritoneum Abdominal cavity  Connective Tissue Membranes Synovial membranes Loose areolar connective tissue only (no epithelial tissue) Line fibrous capsules surrounding joints Line bursae Line tendon sheaths Secrete a lubricating fluid to cushion organs moving against each other during muscle activity © 2018 Pearson Education, Ltd. Summary of the major functions, characteristics, and body locations of the four tissue types: epithelial, connective, muscle, and nervous tissues. Summary of Tissues 54  Dr Hisham Alshaikhli M.B.Ch.B, M.Sc, Ph.D, PGCertMedTech-NZ Assistant Professor College of Nursing – Qatar University [email protected] Office hours: Mondays 12 pm-1 pm – Building I03 – Office 504