Presentation is loading. Please wait.

Presentation is loading. Please wait.

Laboratory Exercise 5 “Histology”.

Similar presentations


Presentation on theme: "Laboratory Exercise 5 “Histology”."— Presentation transcript:

1 Laboratory Exercise 5 “Histology”

2 Histology In this exercise, you will identify the four major types of tissues and their subtypes (histology), and relate characteristics of each tissue type with its function and location in the human body. These terms should be familiar to you: Epithelial (simple, stratified, psedostratified, squamous, cuboidal, columnar, transitional; cilia, villi, goblet), Connective (loose [areolar or adipose], dense, cartilage [chondrocytes, lacunae, chondroitin], bone [osteocytes, lacnae, canaliculi, fluid [RBC, WBC, plasma), Muscle (skeletal, smooth, cardiac; striations, nuclei, intercalation) and Nervous tissue (neurons, glia; soma, axon, dendrite). This laboratory exercise correlates with Chapter 4 of your lecture textbook; Exercise 5 of your laboratory manual

3 Laboratory Lecture

4 An Introduction to Tissues (Histology)
Tissues are structures with discrete structural and functional properties Tissues in combination form organs, such as the heart or liver Organs can be grouped into 11 organ systems Histology is the study of tissues

5 There are Four Types of Tissue
Tissues are collections of cells and cell products that perform specific, limited functions Four types of tissue Epithelial tissue covers the body, lines body cavities, internal passages and forms glands Connective tissue provides protection, support, immunity, energy storage (fat) and transportation Muscle tissue facilitates body movement, heat generation and material movement Neural tissue detects stimuli and responds

6 Epithelial Tissue Epithelial tissue is composed of epithelia and glands: Epithelia are layers of cells covering internal or external surfaces (singular – epithelium) Glands are structures that produce secretions The functions of epithelial tissue include: Providing Physical Protection Controlling Permeability Providing Sensation Produce Specialized Secretions (from the glandular epithelium)

7 Note: We will not examine gland histology in lab.

8 Epithelia is characterized by:
Polarity (apical and basolateral surfaces) – necessary for cellular (epithelial) function Intercellular connections (at cell junctions) – facilitating support and communication Attachment to a structural element (basement membrane or basal lamina) Avascularity (no blood vessels) – blood has to diffuse to these tissues Regeneration – germinative cells near the basement membrane divide by mitosis and replace cells

9 A little more about polarity, connections and attachment…
Apical surfaces Microvilli increase absorption & secretion Cilia move fluid Basolateral surface Cell attachment to the basement membrane and adjacent epithelia

10 2. Intercellular Connections
Support and communication is facilitated by extracellular proteins (ropes that tie cells together) CAM’s (cell adhesion molecules) are transmembrane proteins Proteoglycans are intercellular cement Glycosaminoglycans – made of (hyaluronic acid) The contact points are termed Cell junctions Tight junctions Gap junctions Desmosomes

11 Animation: Tight Junctions
Tight junctions prevent fluid from moving across a layer of cells 0.5 µm Tight junction Animation: Desmosomes Intermediate filaments Desmosome Desmosome Gap junctions 1 µm Figure 6.32 Intercellular junctions in animal tissues Animation: Gap Junctions Extracellular matrix Space between cells Gap junction Plasma membranes of adjacent cells 0.1 µm

12 supplemental slide At tight junctions, membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid They are usually found near the apical surface of a cell Isolates contents of the lumen from the basolateral side Desmosomes (anchoring junctions) fasten cells together into strong sheets Hemidesmosomes attach cells to the basal lamina Gap junctions (communicating junctions) provide cytoplasmic channels between adjacent cells They allow rapid communication between cells, like in cardiac and smooth muscle tissue (functional syncytium)

13 supplemental slide tight junction gap junction hemidesmosome
Interlocking junctional proteins Tight junction tight junction Adhesion belt Terminal web Spot desmosome Adhesion belt Gap junctions Hemidesmosome gap junction Embedded proteins (connexons) Intermediate filaments Clear layer Basement membrane Dense layer Dense area hemidesmosome Cell adhesion molecules (CAMs) Proteoglycans spot desmosome 13

14 3. Attachment to a structural element
The clear layer (lamina lucida) is composed of thin fibers It is secreted by epithelia and is a barrier to proteins The dense layer (lamina densa) is composed of thick fibers It is produced by connective tissue, providing strength and filtration

15 Classification of Epithelia
(Singular = Epithelium; Plural = Epithelia) There are two classes of epithelia The first is based on shape Squamous epithelia is thin and flat Cuboidal epithelia is square shaped Columnar epithelia is tall, slender rectangles The second is based on layers Simple epithelium has a single layer of cells Stratified epithelium has several layers of cells

16 16

17 …the upcoming slides show the different kinds of epithelia in our bodies they are a blending of shape and layering! This is PERFECT lab practical exam material!

18 Figure 4-3a Squamous Epithelia
Simple Squamous Epithelium LOCATIONS: Mesothelia lining ventral body cavities; endothelia lining heart and blood vessels; portions of kidney tubules (thin sections of nephron loops); inner lining of cornea; alveoli of lungs FUNCTIONS: Reduces friction; controls vessel permeability; performs absorption and secretion Cytoplasm Nucleus Connective tissue LM  238 Lining of peritoneal cavity One flat layer of cells – permeability; i.e. capillaries! 18

19 Figure 4-3b Squamous Epithelia
Stratified Squamous Epithelium LOCATIONS: Surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina FUNCTIONS: Provides physical protection against abrasion, pathogens, and chemical attack Squamous superficial cells Stem cells Basement membrane Connective tissue Surface of tongue LM  310 Many flat layers of cells – physical protection; i.e. skin! 19

20 Figure 4-4a Cuboidal and Transitional Epithelia
Simple Cuboidal Epithelium LOCATIONS: Glands; ducts; portions of kidney tubules; thyroid gland Connective tissue FUNCTIONS: Limited protection, secretion, absorption Nucleus Cuboidal cells Basement membrane Kidney tubule LM  650 One cuboidal layer of cells – secretion and absorption; i.e. kidney tubule cells! 20

21 Figure 4-4b Cuboidal and Transitional Epithelia
Stratified Cuboidal Epithelium (RARE) LOCATIONS: Lining of some ducts (rare) FUNCTIONS: Protection, secretion, absorption Lumen of duct Stratified cuboidal cells Basement membrane Nuclei Connective tissue Sweat gland duct LM  500 (RARELY SEEN) Many cuboidal layers of cells – permeability; i.e. sweat gland duct! 21

22 Transitional Epithelium is an unusual stratified type:
It tolerates repeated cycles of stretching and recoiling and returns to its previous shape without damage The Appearance changes as stretching occurs Transitional Epithelium LOCATIONS: Urinary bladder; renal pelvis; ureters FUNCTIONS: Permits expansion and recoil after stretching Epithelium (relaxed) Basement membrane Connective tissue and smooth muscle layers Empty bladder LM  400 Epithelium (stretched) Basement membrane LM  400 Connective tissue and smooth muscle layers Full bladder LM  400 Urinary bladder Many unusual cuboidal layers of cells – expansive; i.e. bladder! 22

23 Figure 4-5a Columnar Epithelia
Simple Columnar Epithelium LOCATIONS: Lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys Microvilli Cytoplasm FUNCTIONS: Protection, secretion, absorption Nucleus Basement membrane Loose connective tissue Intestinal lining LM  350 One columnar layer of cells – permeability; i.e. intestinal lining! 23

24 Figure 4-5b Columnar Epithelia
Pseudostratified Ciliated Columnar Epithelium is an unusual cellular type: It is composed of several different types of cells Pseudostratified Ciliated Columnar Epithelium LOCATIONS: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract Cilia Cytoplasm FUNCTIONS: Protection, secretion, move mucus with cilia Nuclei Basement membrane Loose connective tissue Trachea LM  350 Several cellular layers of cells – movement, i.e. mucociliary escalator of the lung! 24

25 Figure 4-5c Columnar Epithelia
Stratified Columnar Epithelium LOCATIONS: Small areas of the pharynx, epiglottis, anus, mammary glands, salivary gland ducts, and urethra Loose connective tissue Deeper basal cells FUNCTION: Protection Superficial columnar cells Lumen Lumen Cytoplasm Nuclei Basement membrane Salivary gland duct LM  175 Many columnar layers of cells – protection; salivary gland duct! 25

26 Characteristics of Connective Tissue
Connective tissues are found deeper in the body They have very few cells (there is much intercellular space) with an expansive extracellular matrix The extracellular matrix consists of: Ground substance (fluid, rubbery or solid stuff) Determines the specialized function It is clear, colorless and viscous Connective Tissue Fibers (next slide…)

27 The different types of Connective Tissue Fibers
Collagen fibers are the most common type They are long, strong, flexible and resist stretching They are in the tissues of the dermal layer of the skin, tendons, ligaments, cartilage and bone Reticular fibers are a thin network (stroma) of interwoven fibers They are strong and flexible, and resist force in many directions (stabilize functional parenchymal cells) They are in the tissues of the lymph nodes, spleen and basement membranes (acts as an organ sheath) Elastic fibers are elastic, branched and wavy (elastin) They are in the tissues of the skin, lungs and arteries This reflects a balance between tension and flexibility

28 The Cells and Fibers of Connective Tissue Proper (cartoon)
Reticular fibers Mast cell Melanocyte Elastic fibers Fixed macrophage Plasma B cell Free macrophage Collagen fibers Blood in vessel Fibroblast Adipocytes (fat cells) Mesenchymal cell Ground substance Lymphocyte 28

29 Connective Tissues have defined functions…
Establishing a structural framework for the body Transporting fluids and dissolved materials Protecting delicate organs Supporting, surrounding, and interconnecting other types of tissue Storing energy reserves, especially in the form of triglycerides Defending the body from invading microorganisms

30 Classification of Connective Tissues
Connective tissue proper - connect and protect Categorized as loose or dense connective tissue Loose: has more ground substance (i.e. fat) Dense: has more fibers (i.e. tendons) Fluid connective tissues – transport stuff i.e. Blood and lymph Supporting connective tissues – structural strength i.e. Cartilage and bone

31 Connective Tissue Proper Cell Popluations
Permanent residents: (don’t move about) Fibroblasts: are the most abundant cell type, are found in all connective tissue proper populations and produce proteins of the matrix Fibrocytes: are the second most abundant cell type, are found in all connective tissue proper populations and maintain matrix proteins Adipocytes: are fat cells; they store triglycerides (fat molecules) Mesenchymal cells: are stem cells that respond to injury or infection; they differentiate into fibroblasts, macrophages, etc… Fixed Macrophages: are fixed phagocytic cells; engulf pathogens, dead or dying cells Non-permanent residents: (motile) Mast cells: reside near blood vessels; they secrete histamine (inflammatory mediator) and heparin (anti-coagulant) Free Macrophages: are free phagocytic cells; engulf pathogens, dead or dying cells Lymphocytes: are specialized immune cells in the lymphatic system (T and B cells - includes immune protective and antibody secreting cells) Microphages: are phagocytic blood cells that destroy pathogens (neutrophils, eosinophils) Melanocytes: produce melanin (brown pigment) Plasma B Cells: antibody producing White Blood Cells

32 The Cells and Fibers of Connective Tissue Proper (cartoon)
Reticular fibers Mast cell Melanocyte Elastic fibers Fixed macrophage Plasma B cell Free macrophage Collagen fibers Blood in vessel Fibroblast Adipocytes (fat cells) Mesenchymal cell Ground substance Lymphocyte free vs. fixed cell types 32

33 Loose Connective Tissues
Loose Connective Tissues are the “packing materials” of the body; they fill spaces between organs There are three types in adults Areolar Adipose Reticular

34 1. Areolar Tissue (little space)
Areolar tissue provides padding and is flexible, allowing for stretching It is a loose arrangement of fibers and cells in an abundant viscous ground substance Thus, it serves as a passageway for nerves and blood vessels It is widely distributed; it underlies all epithelia, is between muscles and forms a subcutaneous layer with adipose tissue

35 Adipocytes (white adipose cells)
2. Adipose Tissue Adipocytes (fat cells) take up most of the space They do not divide; they expand to store more fat (don’t we know it!) and shrink as fat is released Mesenchymal cells divide and differentiate to produce more fat cells when more storage is needed Adipose Tissue LOCATIONS: Deep to the skin, especially at sides, buttocks, breasts; padding around eyes and kidneys FUNCTIONS: Provides padding and cushions shocks; insulates (reduces heat loss); stores energy Adipocytes (white adipose cells) LM  300 Adipose tissue

36 there is white fat and there is dark fat…
Most common Stores fat molecules Absorbs shock(s) Slows heat loss (insulation) Brown fat More vascularized Adipocytes have many mitochondria When it is stimulated by the nervous system, fat breakdown accelerates, releasing energy as heat Children have more brown fat

37 3. Reticular Tissue Reticular tissue is a loose network of reticular fibers that is filled with fibroblasts and white blood cells Reticular tissue forms a supportive framework (stroma) for the functional cells (parenchyma) of the lymphoid organs The reticular organs include the spleen, liver, lymph nodes, thymus and bone marrow Reticular Tissue LOCATIONS: Liver, kidney, spleen, lymph nodes, and bone marrow FUNCTIONS: Provides supporting framework Reticular fibers Reticular tissue from liver LM  375 Reticular Tissue

38 Dense Connective Tissues
Dense Connective Tissues are tightly packed with high numbers of collagen or elastic fibers There are three types in adults: Dense regular connective tissues Are tightly packed, parallel collagen fibers Dense irregular connective tissues Are interwoven networks of collagen fibers Elastic tissues Are made of elastic fibers

39 1. Dense Regular Connective Tissue is tightly packed and contains parallel collagen fibers
Tendons attach muscle to bone Ligaments connect bone to bone and stabilize organs Aponeuroses attach in sheets to large flat muscles Dense Regular Connective Tissue LOCATIONS: Between skeletal muscles and skeleton (tendons and aponeuroses); between bones or stabilizing positions of internal organs (ligaments); covering skeletal muscles; deep fasciae Collagen fibers FUNCTIONS: Provides firm attachment; conducts pull of muscles; reduces friction between muscles; stabilizes relative positions of bones Fibroblast nuclei Tendon LM  440

40 2. Dense Irregular Connective Tissue is densely packed, randomly arranged collagen fibers
It withstands stresses applied in different directions Found in the deep layer of the skin (dermis), the thick fibrous capsules around organs such as the kidney, and around bone (periosteum) and cartilage (perichondrium) Dense Irregular Connective Tissue LOCATIONS: Capsules of visceral organs; periostea and perichondria; nerve and muscle sheaths; dermis FUNCTIONS: Provides strength to resist forces applied from many directions; helps prevent overexpansion of organs such as the urinary bladder Collagen fiber bundles Deep dermis LM  111

41 Figure 4-11c Dense Connective Tissues
3. Elastic Tissue is made of elastic fibers Elastic Tissue LOCATIONS: Between vertebrae of the spinal column (ligamentum flavum and ligamentum nuchae); ligaments supporting penis; ligaments supporting transitional epithelia; in blood vessel walls Elastic fibers FUNCTIONS: Stabilizes positions of vertebrae and penis; cushions shocks; permits expansion and contraction of organs Fibroblast nuclei Elastic ligament LM  887 41

42 2. Fluid Connective Tissue Cell Populations
Fluid Connective Tissues include the blood and lymph, which are composed of a watery matrix of dissolved proteins and cells The blood contains formed elements (cells or cell fragments)Red blood cells (erythrocytes)White blood cells (leukocytes)Platelets The lymph forms as interstitial fluid enters the lymphatic vesselsThis material is returned to the venous system of the heartIt is monitored by the immune system (lymph nodes; lymphocytes)

43

44 3. Supporting Connective Tissues
Supporting connective tissues buttress soft tissues and body weight, and are composed of: Cartilage – a gel-type ground substance that aids in shock absorption and protection Bone – a calcified material that is made rigid by the incorporation of calcium salts and minerals Bone aids in weight support

45 Cartilage Cartilage is composed of chondrocytes, which produce the rubbery gel matrix of proteoglycan (chondroitin sulfate) and protein fibers Chondrocytes are surrounded by lacunae Cartilage is avascular: Cartilage damage is difficult to repair (chondrocytes produce antiangiogenesis factor) The perichondrium is a surrounding layer, offering protection, attachment to other tissues, maintenance and growth Cartilage grows by two mechanisms (next slide)

46 There are three types of cartilage…
Hyaline cartilage Elastic cartilage Fibrocartilage (fibrous cartilage)

47 1. Hyaline Cartilage offers stiff, flexible support
It reduces the friction between bones Found in synovial joints, rib tips, sternum, and trachea

48 2. Elastic Cartilage is supportive but bends easily
Found in external ear and epiglottis

49 3. Fibrocartilage (Fibrous Cartilage) limits movement
It prevents bone-to-bone contact It pads knee joints, is found between pubic bones and between intervertebral discs

50 Bone Bone (osseous tissue) is strong and resists shattering
The functional unit of bone is the osteon with a centrally located canal that feeds the bone cells through canaliculi tributaries Bone cells (osteocytes) are arranged in circular lacunae within a matrix of calcified calcium salt deposits and flexible collagen fibers The periosteum covers bone surfaces

51 A Comparison of Cartilage and Bone
51

52 Muscle Tissue Muscle Tissue is specialized for contraction and produces all body movement There are three types of muscle tissue: Skeletal muscle tissue Large body muscles responsible for movement Cardiac muscle tissue Found only in the heart Smooth muscle tissue Found in walls of hollow, contracting organs (blood vessels; urinary bladder; respiratory, digestive, and reproductive tracts)

53 Muscle cells are classified by three criteria:
Striation Do the cells have a banded appearance or not? Nucleation Do the cells have a single nucleus or many? Control Are the cells controlled voluntarily (consciously) or involuntarily (autonomically)

54 Skeletal Muscle cells (myofibers)
Long and thin striated cells that are multinucleated (what does multinucleated and striated mean?) Under voluntary (somatic) control New fibers are produced by stem cells (myosatellite cells)

55 Cardiac Muscle cells (cardiocytes)
Short and branched, striated cells with a single nucleus The branching networks are connected at intercalated discs They are under involuntary (autonomic) control and are egulated by pacemaker cells It is difficult to regenerate cardiac muscle cells

56 Smooth Muscle cells Small and tapered, non-striated cells with a single nucleus Can divide and regenerate! Very important!

57 Neural Tissue Neural Tissue is also called nervous or nerve tissue and is specialized for conducting electrical impulses Rapidly senses internal or external environment Processes information and controls responses Neural tissue is concentrated in the central and peripheral nervous system CNS: Brain & spinal cord (integrative nerves) PNS: Senses and nerves (afferent and efferent nerves)

58 There are two types of neural cells in the CNS
Neurons Nerve cells - Perform electrical communication Neuroglia Supporting cells - Repair and supply nutrients to neurons

59 Neurons are generally composed of:
Cell body Contains the nucleus and nucleolus Dendrites Short branches extending from the cell body Receive incoming signals Axon (nerve fiber) Long, thin extension of the cell body Carries outgoing electrical signals to their destination

60 NEUROGLIA (supporting cells)
Figure Neural Tissue NEURONS NEUROGLIA (supporting cells) Nuclei of neuroglia • Maintain physical structure of tissues Cell body • Repair tissue framework after injury • Perform phagocytosis • Provide nutrients to neurons • Regulate the composition of the Axon interstitial fluid surrounding neurons Dendrites Nucleolus Nucleus of neuron LM  600 Dendrites (contacted by other neurons) Axon (conducts information to other cells) Microfibrils and microtubules Mitochondrion Nucleolus Nucleus Contact with other cells Cell body (contains nucleus and major organelles) A representative neuron (sizes and shapes vary widely) 60

61 What procedures are we doing?
You will observe simple stained slides, identify different tissues in the human body, and correlate a relationship of those tissues with their location and function.

62 Resources available… Anatomy and Physiology Laboratory Study Pages; submenu: Tissues

63

64 Classifying Epithelia according to the shape of the cells
64

65 Classifying Epithelia according to the layering of the cells
65


Download ppt "Laboratory Exercise 5 “Histology”."

Similar presentations


Ads by Google