General Histology

What is Anatomy?

• Anatomy (= morphology): study of body’s structure

• Branches of Anatomy– Gross: Large structures– Surface: Landmarks– Histology: Cells and Tissues– Developmental: Structures change through life– Embryology: Structures form and develop before birth

Anatomical Directions• Anatomical position• Regions

– Axial vs. Appendicular• Anatomical Directions-It’s all Relative!

– Anterior (ventral) vs. Posterior (dorsal)– Medial vs. Lateral– Superior (cranial) vs. Inferior (caudal)– Superficial vs. Deep– Proximal vs. Distal

• Anatomical Planes– Frontal = Coronal– Transverse = Horizontal = Cross Section– Sagittal

The Animal Cell Structure

Tissues: groups of cells closely associated that have a similar structure and perform a related function

• Four types of tissue– Epithelial– Connective– Muscle– Nervous

• Most organs contain all 4 types• Tissue has non-living extracellular material

between its cells

Tissue Types in the Human� Epithelial

� primarily used for protection� Connective

� primarily used for support� Nerve

� primarily used for control� Muscle

� primarily used for movement

EPITHELIAL TISSUE: sheets of cells cover a surface or line a cavity

(tissue type #1)

• Functions– Protection– Secretion– Absorption– Ion Transport– Slippery Surface

Characteristics of Epithelium

• Cellularity• Specialized Contacts• Polarity

– Apical vs. Basal

• Supported by Connective Tissue• Avascular• Innervated• Regenerative

Classification of Epithelium-based on number of layers and cell shape

• Layers– Simple – Stratified– Psuedostratified

• Stratified layers characterized by shape of apical layer

• Shapes– Squamous– Cuboidal– Columnar– Transitional

Pg 71

Naming Epithelial Tissues• Epithelial tissues are named in the following

manner:First word: Number of layers (simple, stratified, pseudostratified)Second word: Shape of cell (squamous, cuboidal, columnar)Third word: Describes the apical surface if there are structures (cilia or microvilli) or materials present (keratin).

From the name given you can tell much about the tissue. For example pseudostratified columnar ciliated epithelial. What can you tell from the name about the tissue?

1. It is one cell- layer thick. 2. It is column shaped. 3. It has cilia on its apical surface.

Types of Epithelial Tissues

• Simple squamous: This type is found lining blood vessels and is called endothelium. It is also in the alveoli or airs of of the lungs. This tissue allows the rapid exchange of materials by diffusion and osmosis from cell to cell.

Types of Epithelial Tissues• Stratified squamous: This

type of epithelium is present in areas where there is wear and tear on the tissue which are constantly having cells sloughed away or being rubbed off by abrasion. There are two types of stratified squamous. Keratinized and Non-keratinized. Keratin is a layer a waterproof protein on the apical surface of stratified squamous keratinized epithelium (skin).

Mouth, throat, esophagus, urethra, skin (keratinized)

Types of Epithelial Tissues

• Stratified squamous: Stratified squamous epithelial non-keratinized lines the oral cavity and the esophagus and the vagina of the female reproductive system.

Types of Epithelial Tissues• Stratified squamous: Stratified squamous

epthithelium keratinized Keratin is a layer a waterproof protein on the apical surface of stratified squamous keratinized epithelium (skin).

Types of Epithelial Tissues

• Simple cuboidal: Simple cuboidal cells are common in secretory glands and in the collecting tubules where they are involved with reabsorption of materials as urine is being produced.

Kidney tubules, glands, lining of terminal bronchioles, etc.

Types of Epithelial Tissues• Simple columnar: Simple columnar is located in various areas

of the body. It is commonly found in the lining of the small and large intestine where it is involved with absorption of molecules from digested food and re-absorption of water. In the small intestine the apical surface of these cells have microvilli present on their surface and specialized gland cells called goblet cells which produce and secrete mucus.

microvilli on apical surface

Glands, bronchioles, stomach, intestines, bile ducts, etc.

Types of Epithelial Tissues• Pseudostratified columnar ciliated: This tissue appears to

be stratified but is actually one layer of irregularly shaped cells. The apical surface of these cells have tiny, hair-like projections called cilia, which are involved with the movement across the surface of the cells. This epithelial tissue also has the mucus secreting goblet cells present. This tissue forms the lining of the trachea, bronchi, and lining of the Fallopian tubes (oviducts) of female.

Lines nasal cavity & sinuses, auditory tubes, trachea, bronchi

Sweat gland ducts, salivary gland ducts, etc.

Mammary gland ducts, larynx, urethra (males)

Bladder lining, ureters, and superior urethra

Features of Apical Surface of Epithelium

Microvilli: (ex) in small intestine

Finger-like extensions of the plasma membrane of apical epithelial cell

Increase surface area for absorption

Cilia: (ex) respiratory tubes

Whip-like, motile extension of plasma membrane Moves mucus, etc. over epithelial surface 1-way

Flagella: (ex) spermatoza

Extra long cilia Moves cell

Features of Lateral Surface of Epithelium

• Cells are connected to neighboring cells via:– Proteins-link cells together, interdigitate– Contour of cells-wavy contour fits together– Cell Junctions

• Desmosomes-adhesive spots on lateral sides linked by proteins/filaments, holds tissues together

• Tight Junctions-at apical area, plasma membrane of adjacent cells fuse, nothing passes

• Gap junction- spot-like junction occurring anywhere made of hollow cylinders of protein,

lets small molecules pass

Pg 80

Desomosomes

Features of the Basal Surface of Epithelium

• Basement membrane = Sheet between the epithelial and connective tissue layers– Attaches epithelium to connective tissue below– Basal lamina: thin, non-cellular, supportive sheet Made of

proteins• Superficial layer• Acts as a selective filter• Assists epithelial cell regeneration by moving new cells

– Reticular fiber layer• Deeper layer• Support

Glands: epithelial cells that make and secrete a water-based substance w/proteins

• Exocrine Glands– Secrete substance onto body surface or

into body cavity – Have ducts (simple vs. compound)– Unicellular (goblet cells) or

Multicellular (tubular, alveolar, tubuloalveolar)

– (ex) salivary, mammary, pancreas, liver

Goblet cell in small intestine

Glands: epithelial cells that make and secrete a water-based substance w/proteins

• Endocrine Glands– Secrete product into blood stream– Either stored in secretory cells or in follicle

surrounded by secretory cells– Hormones travel to target organ to increase

response (excitatory)– No ducts– (ex) pancreas, adrenal,

pituitary, thyroidThyroid gland: hormone in follicles (F)

released into capillaries (C)

4 Types of Connective Tissue

1) Connective Tissue Proper2) Cartilage

3) Bone Tissue4) Blood

Connective Tissue (CT): most abundant and diverse tissue

(tissue type #2)

• Four Classes• Functions include connecting, storing & carrying

nutrients, protection, fight infection• CT contains large amounts of non-living

extracellular matrix• Some types vascularized

1) Connective Tissue Proper

• Two kinds: Loose CT & Dense CT• Loose Areolar Tissue

– Underneath epithelial tissue– Functions

• Support and bind to other tissue• Hold body fluids• Defends against infection• Stores nutrients as fat

– Each function performed by different kind of fiber in tissue

• Matrix–Ground substance–Fibers

• Cells

Connective Tissue

Connective Tissue� Matrix - “non-living” component of connective tissue

� Ground substance� Proteoglycan aggregates - pine tree shaped molecules

� Glycosaminoglycans - neg charged binds Na+ & K+ ….. attract H20

� Hyaluronic Acid - slippery polysaccharride� Chondronectin, Osteonectin, etc.

� forms viscous “adhesive gel” in tissues� Fluid - Contains gasses & nutrients� Minerals – I.E. Calcium salts

� Fibers� Collagen, Elastin, and Reticular Fibers

Fibers in Connective Tissue

• Fibers For Support– Reticular: form networks for structure & support

(ex) cover capillaries– Collagen: strongest, most numerous, provide tensile

strength (ex) dominant fiber in ligaments– Elastic: long + thin, stretch and retain shape (ex) dominant fiber in elastic cartilage

In Connective Tissue Proper

• Fibroblasts: cells that produce all fibers in CT, produce + secrete protein subunits to make them, produce ground matrix

• Interstitial (Tissue) Fluid: derived from blood in CT proper; medium for nutrients, waste + oxygen to travel to cells; found in ground matrix

• Ground Matrix (substance): part of extra-cellular material that holds and absorbs interstitial fluid, jelly-like with sugar & protein molecules

Defense from Infection

• Areolar tissue below epithelium is body’s first defense• Cells travel to CT in blood

– Macrophages-eat foreign particles– Plasma cells-secrete antibodies, mark molecules for

destruction– Mast cells-contain chemical mediators for inflammation

response– White Blood Cells = neutrophils, lymphocytes, eosinophils-

fight infection• Ground substance + cell fibers-slow invading

microorganisms

Areolar Connective Tissue Model

Pg 85Histological slide

Specialized Loose CT Proper• Adipose tissue-loaded with adipocytes, highly

vascularized, high metabolic activity– Insulates, produces energy, supports

• (eg) in hypodermis under skin

• Reticular CT-contains only reticular fibers– Forms caverns to hold free cells

• (eg) bone marrow, holds blood cells– Forms internal “skeleton” of some organs

• (eg) lymph nodes, spleen

Dense/Fibrous Connective Tissue• Contains more collagen • Can resist extremely strong pulling forces• Regular vs. Irregular

– Regular-fibers run same direction, parallel to pull• (eg) fascia, tendons, ligaments

– Irregular-fibers thicker, run in different directions• (eg) dermis, fibrous capsules at ends of bones

Dense regular Dense irregular

Components of CT Proper Summarized

Cells Matrix

Fibroblasts Gel-like ground substance

Defense cells-macrophages-white blood cells

Collagen fibersReticular fibersElastic fibers

Adipocytes

2) Cartilage• Chondroblasts produce cartilage• Chondrocytes mature cartilage cells• More abundant in embryo than adult• Firm, Flexible• Resists compression

– (eg) trachea, meniscus• 80% water• Avascular (chondrocytes can function w/low oxygen)• NOT Innervated• Perichondrium-dense, irregular connective tissue around

cartilage– growth/repair of cartilage– resists expansion during compression of cartilage

Cartilage in the Body• Three types:

– Hyaline • most abundant• fibrils in matrix• support via flexibility/resilience• (eg) at limb joints, ribs, nose

– Elastic• many elastic fibers in matrix too• great flexibility• (eg) external ear, epiglottis

– Fibrocartilage• resists both compression and

tension• (eg) meniscus, annulus fibrosus

Pg 125

Histology of Cartilage

• Hyaline Cartilage

Histology of Cartilage

• Elastic Cartilage

Histology of Cartilage

• Fibrocartilage

Components of Cartilage Summarized

Cells Matrix

Chondrocytes Gel-like ground substance

Chondroblasts(in growing cartilage)

Lots of water

Some have collagen and elastic fibers

3) Bone Tissue:(a bone is an organ)• Well-vascularized • Function:

– support (eg) pelvic bowl, legs– protect (eg) skull, vertebrae– mineral storage (eg) calcium, phosphate (inorganic component)– movement (eg) walk, grasp objects– blood-cell formation (eg) red bone marrow

• Osteoblasts: secrete organic part of bone matrix

• Osteocytes: mature bone cells, maintain bone matrix• Periosteum: external layer of CT surrounds bone• Endosteum: internal layer of CT lines cavities and covers trabeculae

• Compact bone: dense, external layer– Haversian system = osteon

• long, cylindrical structures run parallel to long axis of bone• within each osteon, groups of concentric tubes (lamella)• Lamella: layer of bone matrix all fibers run in same direction• fibers on each lamella runs in opposite directions to one near it• Haversian canal-runs through center of osteon, contain blood vessels and

nerves• Interstitial Lamella- pieces of bone matrix between osteon• Osteocytes between osteons

Bone Anatomy: Compact bonePg 128

Haversian System = Osteon

lamella

osteon

Pg 131

Pg 132

lamella

• Spongy bone (cancellous bone): internal layer– Trabeculae: small, needle-like pieces of bone form

honeycomb• each made of several layers of lamellae + osteocytes• no canal for vessels• space filled with bone marrow• not as dense, no direct stress at bone’s center

Bone Anatomy: Spongy bone

Pg 130

1

2

3

4

Spongy Bone

Compact Bone

Lamella

Haversian canal

2

1

3

4

Histology of Bone

• “Ground” Compact Bone

Components of Bone Tissue Summarized

Cells Matrix

Osteocytes Gel-like ground substance calcified with inorganic salts

Osteoblasts Collagen fibers

4) Blood: Atypical Connective Tissue

• Function: – Transports waste, gases, nutrients, hormones

through cardiovascular system– Helps regulate body temperature– Protects body by fighting infection

• Derived from mesenchyme• Hematopoiesis: production of blood cells

– Occurs in red bone marrow– In adults, axial skeleton, girdles, proximal

epiphyses of humerus and femur

Blood CellsErythrocytes: (RBC) small, oxygen-transporting

most abundant in bloodno organelles, filled w/hemoglobinpick up O2 at lungs, transport to rest of body

Platelets = Thrombocytes: fragments of cytoplasm

plug small tears in vessel walls, initiates clotting

Leukocytes: (WBC) complete cells , 5 typesfight against infectious microorganisms

stored in bone marrow for emergencies

Histology of Blood and Vessel• Blood Smear

Histology of Blood Vessels

Artery Vein

Components of Blood SummarizedCells Matrix

Erythrocytes (red blood cells)

Plasma (liquid matrix)

Leukocytes(white blood cells)

NO fibers

Platelets

Muscle Tissue (tissue type #3)

• Muscle cells/fibers– Elongated – Contain many myofilaments: Actin & Myosin

• FUNCTION– Movement– Maintenance of posture– Joint Stabilization– Heat Generation

• Three types: Skeletal, Cardiac, Smooth

Skeletal Muscle Tissue(each skeletal muscle is an organ)

• Cells– Long and cylindrical, in bundles– Multinucleate– Obvious Striations

• Skeletal Muscles-Voluntary• Connective Tissue Components:

– Endomysium-surrounds fibers– Perimysium-surrounds bundles– Epimysium-surrounds the muscle

• Attached to bones, fascia, skin• Origin & Insertionpg 235

Cardiac Muscle• Cells

– Branching, chains of cells– Single or Binucleated– Striations– Connected by Intercalated discs

• Cardiac Muscle-Involuntary• Myocardium-heart muscle

– Pumps blood through vessels

• Connective Tissue Component– Endomysium: surrounding cells

Pg 244

Smooth Muscle TissueCells

Single cells, uninucleateNo striations

Smooth Muscle-Involuntary2 layers-opposite orientation (peristalsis)

Lines hollow organs, blood vesselsConnective Tissue Component

Endomysium: surrounds cells

Pg 246

Histology of Muscle Tissue

SMOOTH

CARDIAC

SKELETAL

Nervous Tissue

• Neurons: specialized nerve cells conduct impulses– Cell body, dendrite, axon

• Interneuron: between motor & sensory neuron in CNS

• Characterized by:– No mitosis (cell replication)– Longevity– High metabolic rate

pg 322

Nervous Tissue: control• Support cells (= Glial): nourishment,

insulation, protection– Satellite cells-surround cell bodies within

ganglia– Schwann cells-surround axons– Microglia-phagocytes– Oligodendrocytes-produce myelin sheaths

around axons– Ependymal cells-line brain/spinal cord,

ciliated,help circulate CSF• Brain, spinal cord, nerves

Neuronal Anatomy

• Synapse: cell junction where neurons communicate

• One direction: presynaptic neuron, postsynaptic neuron

• Presynaptic neuron– Synaptic vesicles fuses w/presynaptic

membrane– Neurotransmitters released, – diffuse across synaptic cleft, bind to postsynaptic membrane ٠Creates impulse (action potential) in that neuron

٠Cycle repeats

pg 325

Anatomy of Nerve

Histology of Neuron

Integumentary System

• Skin– Epidermis = epithelium– Dermis = connective tissue

• Hypodermis = connective tissue• Skin Appendages = outgrowths of epidermis

– Hair follicles– Sweat and Sebaceous glands– Nails

Integumentary System

• Functions– Protection

• Mechanical, thermal, chemical, UV

– Cushions & insulates deeper organs– Prevention of water loss– Thermoregulation– Excretion

• Salts, urea, water

– Sensory reception

Layers of the Epidermis Stratum corneum

Dead keratinocytes

Stratum lucidumDead keratinocytes

Stratum granulosumKeratinocytesTonofilamentsLamellated & keratohyaline granules

Stratum spinosumKeratinocytesTonofilamentsLangerhans cells

Stratum basaleKeratinocytesMelanocytesMerkel receptors

DermisHighly innervatedHighly vascularizedCollagen & Elastic fibersMany cell types

FibroblastsMacrophagesMast cellsWhite blood cells

Papillary layer (20%) Areolar CT Hair follicles

Reticular layer (80%) Dense Irregular CT Glands

Sebaceous glands Sweat glands

Smooth muscle fibers

Hypodermis

• Also called superficial fascia• Areolar & Adipose Connective Tissue• Functions

– Store fat– Anchor skin to muscle, etc.– Insulation