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Laboratory Two

Histology

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Histology

• Study of structure and function of tissues– Groups of cells that are structurally and

functionally the same– A combination of living and non-living

material

• Go over each microscope– Illustrate and write anatomical details– Touch only the fine focus knob– Pointer helps you locate the assigned structures

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Four Primary Tissue Types

1. Epithelial - lines & covers surfaces

2. Connective - protects, supports, & binds

3. Muscular - contracts & produces movement

4. Nervous – generates & conducts nerve impulses

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1. Epithelial Tissue (E.T.)

• Lines, covers surfaces both inside & out• Consists of many cells, tightly packed together• Usually arranged in layers (except glands)

– Simple (1 layer) or stratified (2 or more layers)

• Secured to deeper tissue by basement membrane• A free surface is found opposite basement

membrane

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Specific Types of Epithelial Tissues are Characterized by:

• Number of layers:– Simple (1 layer) - secretion, absorption, filtration– Stratified (>2 layers) – wear & tear

• Cell shape– Squamous – flat from side, like fried egg from top

(yolk: nucleous)– Cuboidal - as wide as tall as deep, nucleous in center– Columnar – tall & thin, nucleous elongated

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Simple Squamous Epithelial Tissue

Tissue: simple squamous E. T.Cell: squamous epithelial cellID: flattened cells, mosaic shapeLocation: alveoli of lungsFunction: diffusion

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Tissue: simple cuboidal E.T.Cell: cuboidal epithelial cell

ID: round centrally located nucleousLocation: salivary glandsFunction: secretion

Simple Cuboidal Epithelial Tissue

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Simple Columnar Epithelial TissueTissue: simple columnar E. T.Cell: columnar epithelial cellID: elongated nuclei, closer to BM,

one layerLocation: small intestineFunction: secretion of digestive

enzymes, absorption of nutrients

Higher magnification(showing goblet cells)

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Pseudostratified Ciliated Columnar E. T.

Higher magnification(showing cilia and

goblet cell)

Tissue: P. C. C. E.T. Cell: columnar epithelial cell with

their elongated nuclei appear in multi-layer (cells with different dimension are arranged in one layer)

ID: ciliatedLocation: tracheaFunction: protection (cilia moves

mucous along with unwanted substances in air upwards

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Stratified Squamous Epithelial TissueTissue: S. S. E.T.Surface cells: Squamous E. C. ID: multiple layer, squamous

cells at free surface (As cells mature, they change shape)

Location: esophagusFunction: protection against

wear & tear

Lower magnification

(see abrupt change in tissue type at BM)

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Transitional Epithelial Tissue

Relaxed urinary bladder

Tissue: T. E.T. ID: stratified with cuboidal ECLocation: urinary bladder (distended)Function: accommodates fluctuation

in the volume of fluid, protects against caustic effect of urine

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E.T. Assignment

• View each assigned E.T. through microscopes or as micrographs

• Complete your histology worksheet in your handout– Illustrate the specific tissue– Label the assigned structures on your

illustration– Record & learn one location and one function

for each tissue

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2. Connective Tissue (C.T.)• Protects, supports, binds

• Consists of relatively few cells scattered in non-living matrix

• Matrix varies– Fluid (e.g. plasma of blood C.T.)

– Semi-solid matrix of cartilage

– Solid (e.g. bone)

– May contain various types of protein fibers arranged in various ways and with a range of densities

• Cells vary too– RBCs carry oxygen and WBCs & macrophages are protective

– Chondrocytes secrete the matrix in cartilage C.T.

– Osteocytes secrete bony matrix in osseous C.T.

– Fibroblasts secrete fibers

– Adipose cells store fat

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Osseous Connective Tissue

Osteocytes inside lacunae

(magnified)

Tissue: Osseous C. T.Cell: OsteocytesID: Cells arranged circularly

around central canal, deposit the matrix in layers call lamella, nucleous (dark dots)

Location: skeletonFunction: support, protection

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Hyaline Cartilage Connective Tissue

Chondrocytes inside lacunae

(magnified)

Tissue: Hyaline cartilage C. T.Cell: ChondrocytesID: Cells with clear periphery

embedded in a semi-fluid matrix, nucleous (dark dots)

Location: Capping the end of bones

Function: support, protection, cushion

Chondrocytes inside lacunae

(magnified)

Tissue: Hyaline cartilage C. T.Cell: ChondrocytesID: Cells with clear periphery

embedded in a semi-fluid matrix, nucleous (dark dots)

Location: Capping the end of bones

Function: support, protection, cushion

Fibrocartilage Connective Tissue

Tissue: Fibrocartilage C. T.

Cell: Chondrocytes

ID: Cells (dark dots) embedded in a matrix with blue collagen fibers

Location: Disks between the vertebrae of spinal column

Function: cushion

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Dense Fibrous Connective Tissue

Tissue: Dense fibrous C. T.Cell: FibroblastsID: Parallel collagen fibers packed

tightly, nuclei of fibroblasts (dark dots)

Location: tendon (muscle to bone) and ligament (bone to bone)

Function: attachment

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Areolar Connective Tissue

Tissue: Areolar C. T.Cell: Fibroblast (most common)ID: Irregularly & loosely

arranged collagen and elastic fibers, dots are nuclei of fibroblasts

Location: Under the skinFunction: Attachment, support

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Tissue: Adipose C. T.Cell: Adipocyte, signet ring

cells, or fat cellsID: Large clear cells with

nuclei pushed to the sides by fat vacuoles

Location: Breasts, hipsFunction: Energy storage,

cushioning, insulation

Adipose Connective Tissue

Reticular Connective Tissue

Tissue: Reticular CT

Cells: Reticular cells, blood cells

ID: network of reticular fibers embedded in cells

Location: spleen

Function: framework to support free blood cells

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Blood Connective Tissue

Tissue: Blood C. T.Cell: RBC & WBCID: RBC – look like life saver, no

nucleous, high in number WBC – different shapes, have a nucleous, low in number

Location: blood vesselsFunction: gas & nutrients

transport, protection against infection

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C.T. Assignment

• View each assigned C.T.

• Complete illustrations in your worksheet

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3. Muscle Tissue(Contracts producing movement)

• Muscles cells are called fibers• Cells vary in their number of nuclei and shape, and

whether or not they are banded

Tissue: Smooth Muscle

Cell: smooth muscle cell

ID: many nuclei crammed in, no striation

Location: stomach

Function: movement of substances

Tissue: Cardiac Muscle

Cell: cardiac muscle cell

ID: intercalated disks, striated uninucleated

Location: heart

Function: heart pump

Tissue: Skeletal Muscle

Cell: Muscle fiber

ID: Striated with multiple nuclei

Location: arm

Function: movement of body

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4. Nervous Tissue

Tissue: Nervous tissueCell: Multipolar neuronID: Cell body with processesLocation: Nervous systemFunction: Conduction of nerve impulses

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Integumentary System(Skin)

• This organ system consists of 2 layers:– Epidermis: Stratified squamous E.T. – Dermis (papillary and reticular layers):

• Sebaceous & sweat glands• Hair folicle• Arrector pilli muscle• Meissner corpuscles (sense receptors for light touch)

– Hypodermis (not part of skin): Adipose C. T.• Pacinian corpuscles (sense receptors for pressure)

• Learn locations of all four primary tissue types, and the assigned layers and structures on the skin model