Anatomy and Physiology Lecture Unit #2

Histology

Study of structure and function of tissues

Tissue Types

• Epithelium

• Connective

• Muscle

• Neural

Epithelium/Epithelial Tissue Characteristics (1)

• Cover structure, lines body cavities and hollow organs

• Has free surface and basement membrane

• Connective tissues lies below the basement membrane

Epithelium/Epithelial Tissue Characteristics (2)

• Nonvascular

• Little intercellular (between cells) material, tightly packed

• Rapid healing, frequent cell replacement

Epithelium/Epithelial Tissue Functions

• Absorption: epithelial cells absorb nutrients from food

• Secretion: cell releases substance

• Excretion: excess substance cell needs to get rid of

• Diffusion: cells can move one way or another

• Protection

• Distention: specialized for being stretched

Epithelium/Epithelial Tissue Classification

• Simple: 1 cell layer (can be squamous, cuboidal, or columnar)

• Stratified: 2 or more cell layers (can be squamous, cuboidal, or columnar)

• Pseudo-Stratified Columnar: simple but looks stratified (columnar)

• Transitional: number of layers depend on stretching (no cell shape)

Epithelial Cell Shape

• Squamous

• Cuboidal

• Columnar

• Stratified epithelium

• (Squamous) Flat and pancake-shaped

• (Cuboidal) Tall as wide (square)

• (Columnar) Taller than wide (rectangle standing up)

• (Stratified) Cell shape term refers to free surface

Connective Tissue Characteristics

• Abundant intercellular material called matrix

• Matrix contains ground substance and fibers

• Generally vascular

Cells

(cyte - name of cell type)

• Fibroblasts: produce fibers

• Macrophages: phagocytes

• Adipocytes: in adipose

• Chondrocytes: in cartilage

• Osteocytes: in bone

Fibers

• Collagenous: collagen protein - strong

• Elastic: elastin protein - stretchy

• Reticular: collagen protein - branching

Ground Substance

• Gel-like

• Reduced

• Firm-solid: solid but flexible

• Hard-solid: solid can’t bend

• Fluid: plasma (blood)

Epithelia

• Simple Squamous Epithelium

  • Locations

  • Functions

• Locations: lines alveoli, forms capillary walls, lines blood and lymph vessels, covers body cavity membranes

• Functions: Diffusion (gases), filtration, decrease friction (smooth)

Epithelia

• Stratified Squamous Epithelium

  • Locations

  • Functions

  • Features

• Locations: surface of skin, linings of oral cavity, vagina, anal canal, and part of pharynx (where swallowing occurs)

• Functions: Protection

• Features: May be non-keratinizing (alive, moist) or keratinizing (dry, dead cells filled with keratin protein that makes skin waterproof)

Epithelia

• Simple Cuboidal Epithelium

  • Locations

  • Functions

• Locations: covers ovaries, lines kidney tubules and ducts of many glands

• Functions: Absorption, secretion (release of cell product), excretion (cell waste)

Epithelia

• Stratified Cuboidal Epithelium

  • Locations

  • Functions

• Locations: linings of larger ducts of mammary glands, sweat glands, salivary glands, and pancreas

• Functions: protection, secretion

Transitional Epithelium

• Locations:

• Functions:

• Locations: lining of urinary bladder, ureters, and part of urethra

• Functions: protection, distention

Epithelia

• Simple Columnar Epithelium

  • Locations

  • Functions

  • Features

• Locations: lines uterus, stomach, intestines, uterine tubes

• Functions: secretion, absorption, protection production of movement (move an egg into tube)

• Features: may have cilia for movement or microvilli for absorption (brush border), and mucus secreting goblet cells

Epithelia

• Stratified Columnar Epithelium

  • Locations

  • Functions

• Locations: lining ductus deferens, part of male urethra, part of pharnyx

• Functions: protection, secretion

Epithelia

• Pseudo-stratified Columnar Epithelium

  • Locations

  • Functions

  • Features

• Locations: lines respiratory passages

• Functions: protection, secretion, production of movement

• Features: may be ciliated with mucus secreting goblet cells

Connective

• Areolar

  • Locations

  • Functions

• Locations: below skin and below basement membrane of most epithelia

• Functions: binds structures

Connective

• Adipose

  • Locations

  • Functions

• Locations: beneath skin, between muscles, around kidneys and heart, behind eyes, in abdominal membranes

• Functions: adipocytes accumulate triglycerides for energy storage, insulation, and protection

Connective

• Reticular Connective

  • Locations

  • Functions

• Locations: liver, spleen, lymph nodes

• Functions: structural support

Connective

• Dense Connective Tissue

  • Locations

  • Functions

  • Features

• Locations: regular (tendons, ligaments) irregular (dermis of the skin)

• Functions: provides strength

• Features: regular is slow to heal because it is mainly nonvascular (poor blood supply), irregular is vascular

Connective

• Elastic Connective

  • Locations

  • Functions

• Locations: walls of larger arteries, heart chambers, and larger airways, and between vertebrae

• Functions: provides strength with elasticity

Connective

• Blood

  • Locations:

  • Functions:

  • Features:

• Locations: Cardiovascular System

• Functions: transport, protection from infection, prevention of blood loss

• Features: formed elements (cells) in plasma (matrix)

Connective

• Hyaline Cartilage

  • Locations:

  • Functions:

  • Features:

• Locations: ends of bones, tracheal rings, bone models in fetus and child

• Functions: support, bone development

• Feature of all Cartilage: chondrocytes occupy lacunae (caves), tissue is nonvascular but surrounded by vascular perichondrium (region around cartilage)

Connective

• Elastic Cartilage

  • Locations:

  • Functions:

• Locations: external ears, part of larynx

• Functions: support with elasticity

Connective

• Fibrocartilage

  • Locations:

  • Functions:

• Locations: intervertebral disks (cushion), menisci of knee joints

• Functions: support with increased strength and durability (strongest of cartilages)

Connective

• Bone

  • Locations:

  • Functions:

  • Features:

• Locations: skeleton

• Functions: support, protection, attachment sites for muscles, mineral storage

• Features: osteocytes occupy lacunae (bone cells live in caves). Compact bone has osteons with central canals, lamellae, and canailiculi

Gland Classification

• Endocrine Glands:

• Exocrine Glands:

• Endocrine Glands: secrete products directly into blood or tissue fluid (hormones)

• Exocrine Glands: secrete products directly onto a surface, usually via ductE

Exocrine divided into 3

• Cell Number

• Structural Complexity

• Method of Secretion

Exocrine

• Cell Number

• Unicellular (goblet cell)

• Multicellular

Exocrine

• Structural Complexity

• Simple (duct does not branch)

• Compound (duct branches)

Exocrine

• Method of Secretion

• Merocrine (cellular secretion/exocytosis)

• Apocrine (cell apex (top) breaks off)

• Holocrine (gland releases whole cells which disintegrate)

Types of Membranes

• Serous membranes

  • Locations:

  • Secretion:

  • Tissues:

• Line and cover organs within the ventral cavity

• Secretion: serous fluid

• Tissues: simple squamous mesothelium, areolar

Types of Membranes

• Mucous membranes

  • Locations:

  • Secretion:

  • Tissues:

• Locations: line cavities that open to the outside of the body

• Secretion: mucus

• Tissues: various epithelia, areolar

Types of Membranes

• Synovial membranes

  • Locations:

  • Secretion:

  • Tissues:

Locations: line cavities of freely movable joints

Secretion: synovial fluid (lubrication)

Tissues: areolar, adipose

Types of Membranes

• Cutaneous membrane, integumentary membrane, integument, skin

  • Locations:

  • Secretion:

  • Tissues:

Locations: Covers the body

Secretion: sweat, sebum (oil)

Tissues: stratified squamous, epithelium, areolar, irregular dense connective

Integumentary System

• Cutaneous membrane (skin)

- Accessory structures/organs:

• Hair follicles

• Sebaceous glands

• Nails

Epidermis (—- layer of skin)

• Thickness?

• Superficial layer of skin

• 0.08-0.5 mm thick

Strata

• Stratum basale: single layer of cuboidal or columnar stem cells

• Stratum spinosum: 8-10 layers of flatter cells, some of which are stem cells

• Stratum granulosum: missing in thin areas

• Stratum lucidum: only in palms and soles

• Stratum corneum: 15-30 layers of flattened, dead, keratinized cells

Epidermis

• Cell Types

• Keratinocytes: produce keratin

• Melanocytes: produce melanin

• Dendritic cells: protect against microorganisms and superficial cancers

Epidermis

• Keratinization

• Keratinocytes produce and accumulate keratin and eventually die as they are pushed away from the blood vessels of the dermis and toward the skin surface by the reproductive actions of the cells of the strata basale and spinosum

Epidermis

• Epidermal Ridges

• Are present on hands and feet to increase friction

Skin Color

• 3 pigments responsible for skin color

• Melanin

• Hemoglobin

• Carotene

Melanin

• (Brown, yellow-brown, black) produced by melanocytes in the epidermis

  - people have similar numbers of melanocytes but differ in their activity level

  - production promoted by UV radiation

  - protects DNA molecules in deeper cells from UV radiation

Hemoglobin

(Bright red, dark red) in red blood cells in the dermis

Carotene

(Orange-yellow) from vegetables can accumulate in the epidermis and in subcutaneous adipose

Dermis (deep layer of skin)

• Tissues

• Areolar - papillary layer

• Dense irregular connective - reticular layer

• 1-2 mm thick

• Dermal papillae contain capillary loops and sensory receptors

• Highly vascular

Hypodermis

• Region below skin

• Areolar and adipose tissue

• Separates skin from underlying structures

Integumentary System Accessory Organs

• Hair Follicles

• follicle wall formed from epidermal cells

• usually associated with an arrector pilli muscle (makes hair stand up)

Integumentary System Accessory Organs

• Sebaceous Glands

• holocrine glands that secrete sebum for lubrication, moisture, and protection from bacterial infection

Integumentary System Accessory Organs (1)

• Sweat Glands: Apocrine

Apocrine (body odor)

• mainly located in axillae and pubic region

• secrete into hair follicles

• holocrine glands with secretion that may function in olfactory communication

Integumentary System Accessory Organs (2)

• Sweat Glands: Merocrine

• found in most areas of skin

• secrete onto skin’s surface

• secretion functions in thermoregulation and protection from bacterial infection

Functions of Integumentary System

• protects underlying tissue and organs against impact, abrasion, fluid loss, chemical attack, and infection by pathogens

• excrete salts, water, and organic wastes by integumentary glands (sweat glands)

• maintain normal body temp (insulation, evaporative cooling)

• produce melanin, protects underlying tissue (and their DNA) from UV radiation

Functions of Integumentary System

• produces keratin, protects against abrasion and serves as water repellant

• synthesize vitamin D3, steroid converted to calcitriol, hormone important to normal calcium metabolism

• store lipids in adipocytes in dermis and adipose tissue in hypo-dermis

• detect touch, pressure, pain, and temp stimuli, relay that info to nervous system

Organs of Skeletal System?

• bone and joints

• each bone and joint is considered an organ because it consists of more than 1 type of tissue

Functions of Skeletal System

• support

• store minerals and lipids

• produce blood cells

• protection

• leverage

Bone classification by shape

• Long: large limb bones (femur or thighbone)

• Short: wrist and ankle bones (carpal or wrist bone)

• Flat: sternum and cranium bones (parietal bone from roof of skull)

• Irregular: vertebrae and facial bones (sphenoid bone from skull)

Parts of a Long Bone

• Diaphysis (pl. diaphyses)

• Metaphysis (pl. metaphyses)

• Epiphysis (pl. epiphyses)

• Articular cartilage - hyaline cartilage (decreases friction)

• Periosteum - covers outer surface

• Medullary cavity

• Endospeum - lines all internal cavities

• Compact bone - diaphysis and surface of epiphyses

• Spongy bone - cores of epiphyses

• Marrow

  - Red: blood cell production

  - Yellow: adipose for energy storage

Bone Tissue Structure: Compact Bone

• osteon = central canal + concentric lamellae

• lamellae may also be circumferential or interstitial

• osteocytes live in lacunae

• canaliculi connect neighboring lacunae

• perforating canals connect central canal

Bone Tissue Structure: Spongy Bone

• Trabeculae

• Canaliculi

• Trabeculae are small interconnecting bars or plates containing osteocytes in lacunae and lamellae

• Canaliculi open onto surface of each trabecula which supply nutrients to the osteocytes

Joints =

Articulations (where bones connect)

Joints are…

• Classified to extent of movement

• Synarthrosis: no movement (red)

• Amiphiarthrosis: slight movement (yellow)

• Diarthrosis: free movement (green)

Joints are…

• Classified according to articulating tissue

  - Fibrous (ligaments)

• Syndesmosis: interosseous [between bone] ligament (yellow)

• Suture: sutural ligament (red)

• Gomphosis: periodontal ligament (red)

Joints are…

• Classified according to articulating tissue

  - Cartilaginous (cartilage)

• Synchondrosis: hyaline cartilage (red)

• Symphysis: hyaline cartilage and fibrocartilage disc (yellow)

Joints are…

• Classified according to articulating tissue

  - Synovial (joint capsule)

• Classified according to shapes of the articulating surfaces

• Ball and socket (hip joint)

• Conclyloid (wrist)

• Gliding (carpals, tarsals)

• Hinge (elbow, knee)

• Pivot (rotational) (neck)

• Saddle (thumb)

• Synovial Joint Structure

• Articular cartilage

• Joint capsule

  - Fibrous layer (dense regular connective) that is continuous with periostium

• Synovial membrane (areolar) that secretes synovial fluid for lubrication and cushioning

Synovial Joint Structure

• Ligaments

• Ligaments: bind bones together and limit movement

• Some are part of the fibrous layer, some are separate, some run within joint, some surround

Synovial Joint Structure

• Menisci

• Bursae

• Menisci: fibrocartilage pads between articulating surfaces that provide cushioning

Contains thing, branching fibers and is found within the liven, spleen, and lymph nodes

Reticular Connective

Forms the lining of the urinary bladder

Transitional epithelium

Supports the external ear

Elastic cartilage

Lines some respiratory passages (ex. trachea), appears multilayered but is not

Pseudo-stratified columnar epithelium

Forms the superficial layer of the skin

Stratified squamous epithelium

Lines the larger ducts of several glands and has several layers of cells that are about as tall as they are wide

Stratified cuboidal epithelium

Lines the vas deferens and part of the male urethra and has several layers of cells with those at the apical surface being taller than they are wide

Stratified columnar epithelium

Forms the intervertebral disks

Fibrocartilage

Binds the skin to underlying organs and contains both collagenous and elastic fibers

Areolar

Forms tendons and ligaments

Dense regular connective

Forms the walls of capillaries and linings of other blood vessels

Simple squamous epithelium

Allows the larger arteries and the chambers of the heart to expand and recoil

Elastic connective

Found beneath the skin and around the heart and kidneys. Also stores energy in triglycerides

Adipose

Lines the stomach and uterus

Simple columnar epithelium

Covers the ovaries and lines kidney tubules and the ducts of many glands

Simple cuboidal epithelium

Covers the ends of bones where they articulate

Hyaline cartilage

The basic structural unit for compact bone

Osteon

The basic structural unit for spongy bone

Trabecula

Cavity whereto find a bone cell

Lacunae

Name for a bone cell

Osteocyte

Matrix layer in compact bone

Lamella

Contains blood vessels and nerve fibers

Central canal

Term for an end of a long bone

Epiphysis

Term for the central shaft of a long bone

Diaphysis

Decreases friction on the surface of a bone at a joint

Articular cartilage

Covers a bone

Periosteum

Contains yellow bone marrow in an adult

Medullary cavity

Fills the cores of a long bone’s ends

Spongy bone

Forms the wall of a long bone’s shaft and the surface of it’s ends

Compact bone

Lines the cavity in a long bone’s shaft

Endosteum