Tissues

Todays Topics Four Major Tissue Types Epithelial Tissue Connective Tissue Muscle Nervous Tissue Tissue Response to Injury

Tissue Types

What are tissues? Tissues 4 tissue types form all the structures of the human body: – epithelial, connective, muscle, and neural

Epithelial Tissue Covers exposed surfaces Lines internal passageways Forms glands

Connective Tissue Fills internal spaces Supports other tissues Transports materials Stores energy

Muscle Tissue Specialized for contraction Skeletal muscle, heart muscle, and walls of hollow organs

Neural Tissue Carries electrical signals from one part of the body to another Support Cells

Epithelial Tissue

Epithelial Tissues Epithelia: Glands:

What are the special structures and functions of epithelial tissues?

Characteristics of Epithelia 1.Cellularity 2.Polarity 3.Attachment 4.Avascularity 5.Regeneration

Functions of Epithelial Tissue 1.Provide physical protection 2.Control permeability 3.Provide sensation 4.Produce specialized secretions

Specializations of Epithelial Cells 1.Move fluids over the epithelium 2.Move fluids through the epithelium 3.Produce secretions

Figure 4–1 Free Surface and Attached Surface Polarity: – apical and basolateral surfaces

Increasing Surface Area Microvilli increase absorption or secretion Cilia move fluids

Effective Barriers Physical integrity is maintained by: – intercellular connections – attachment to basal lamina – maintenance and repair

Figure 4–2a Intercellular Connections Support and communication

Large Connections CAMs (cell adhesion molecules): Intercellular cement:

Cell Junctions Form bonds with other cells or extracellular material:

Tight Junctions Between 2 cell membranes Figure 4–2b

Tight Junctions Adhesion belt attaches to terminal web Prevents Isolates

Gap Junctions Allow rapid communications Figure 4–2c

Gap Junctions Held together by channel proteins Allow ions to pass

Desmosomes CAMs, dense areas, and intercellular cement Figure 4–2d

Desmososmes Ties cells together Allow bending and twisting

Basal Lamina Lamina lucida: Lamina densa:

Repairing and Replacing Epithelia Epithelia are replaced by division of germinative cells (stem cells) Near basal lamina

Classes of Epithelia Based on shape and layers Table 4–1

Squamous Epithelia Simple squamous epithelium: Mesothelium: Endothelium:

Simple Squamous Epithelium

Stratified Squamous Epithelium Protects against attacks

Stratified Squamous Epithelium

Cuboidal Epithelia Simple cuboidal epithelium: Stratified cuboidal epithelia:

Simple Cuboidal Epithelium

Stratified Cuboidal Epithelium

Transitional Epithelium Urinary bladder

Columnar Epithelia Simple columnar epithelium: Pseudostratified columnar epithelium: Stratified columnar epithelium:

Simple Columnar Epithelium Intestinal lining

Pseudostratified Columnar Epithelium Trachea

Stratified Columnar Epithelium Salivary gland duct

Glandular Epithelia Endocrine and exocrine glands Figure 4–6

Endocrine Glands Release hormones: – into interstitial fluid – no ducts

Exocrine Glands Produce secretions: – onto epithelial surfaces – through ducts

Modes of Secretion Merocrine secretion Figure 4–6a

Modes of Secretion Apocrine secretion Figure 4–6b

Modes of Secretion Holocrine secretion Figure 4–6c

Types of Secretions Serous glands: Mucous glands: Mixed exocrine glands:

Gland Structure Exocrine glands can be classified as: – unicellular glands – multicellular glands

Unicellular Glands Goblet cells are the only unicellular exocrine glands:

3 Characteristics of MEGs Structure of the duct: Shape of the secretory portion of the duct Relationship between ducts and glandular areas

Structure of Multicellular Exocrine Glands Structural classes of exocrine glands Figure 4–7 (1 of 2)

Structure of Multicellular Exocrine Glands Figure 4–7 (2 of 2)

Connective Tissue

What are the structures and functions of different types of connective tissues?

Connective Tissues Connect epithelium to the rest of the body Provide structure Store energy Transport materials

Characteristics of Connective Tissues Specialized cells Solid extracellular protein fibers Fluid extracellular ground substance

The Matrix The extracellular components of connective tissues (fibers and ground substance):

Classification of Connective Tissues Connective tissue proper: Fluid connective tissues: Supportive connective tissues:

Categories of Connective Tissue Proper Loose connective tissue: Dense connective tissue:

8 Cell Types of Connective Tissue Proper Fibroblasts Macrophages Adipocytes Mesenchymal cells Melanocytes Mast cells Lymphocytes Microphages

Connective Tissue Proper Figure 4–8

Fibroblasts The most abundant cell type: – found in all connective tissue proper

Macrophages Large, amoeba- like cells of the immune system:

Adipocytes Fat cells: – each cell stores a single, large fat droplet

Mesenchymal Cells Stem cells that respond to injury or infection: – differentiate into fibroblasts, macrophages, etc.

Melanocytes

Mast Cells Stimulate inflammation after injury or infection: Basophils are mast cells carried by blood

Lymphocytes Specialized immune cells in lymphatic system: – e.g., plasma cells which produce antibodies

Microphages Phagocytic blood cells: – respond to signals from macrophages and mast cells

Fibers in Connective Tissue Proper Collagen fibers:

Fibers in Connective Tissue Proper Reticular fibers:

Fibers in Connective Tissue Proper Elastic fibers:

Ground Substance In connective tissue proper and ground substance: – is clear, colorless, and viscous

Embryonic Connective Tissues Are not found in adults Mesenchyme (embryonic stem cells): Mucous connective tissue:

Loose Connective Tissues The packing materials of the body 3 types in adults: – areolar – adipose – reticular

Areolar Tissue Least specialized Open framework Viscous ground substance Elastic fibers

Adipose Tissue Contains many adipocytes (fat cells) Figure 4–10a

Types of Adipose Tissue White fat: – most common – stores lipid

Types of Adipose Tissue Brown fat: – more vascularized – adipocytes have many mitochondria

Adipose Cells Adipocytes in adults do not divide: Mesenchymal cells divide and differentiate:

Reticular Tissue Provides support Figure 4–10b

Reticular Tissue Complex, 3-dimensional network Supportive fibers (stroma): Reticular organs:

Dense Connective Tissues Connective tissues proper, tightly packed with high numbers of collagen or elastic fibers: – dense regular connective tissue – dense irregular connective tissue – elastic tissue

Dense Regular Connective Tissue Attachment and stabilization Tightly packed, parallel collagen fibers: Figure 4–11a

Dense Irregular Connective Tissue Strength in many directions Interwoven networks of collagen fibers: Figure 4–11b

Elastic Tissue Made of elastic fibers: – e.g., elastic ligaments of spinal vertebrae Figure 4–11c

Fluid Connective Tissues Fluid connective tissues: – blood and lymph – watery matrix of dissolved proteins – carry specific cell types (formed elements)

Formed Elements of Blood Figure 4–12

Lymph Extracellular fluid: – collected – monitored – transported – returned

Supportive Connective Tissues Support soft tissues and body weight: – cartilage: – bone:

Cartilage Matrix Proteoglycans derived from chondroitin sulfates Ground substance proteins Cells surrounded by lacunae

Cartilage Structure No blood vessels: Perichondrium:

Cartilage Growth (1 of 2) Interstitial growth Figure 4–13a

Cartilage Growth (2 of 2) Appositional growth Figure 4–13b

Types of Cartilage Hyaline cartilage: Elastic cartilage: Fibrocartilage:

Hyaline Cartilage Reduces friction in joints Figure 4–14a

Elastic Cartilage Flexible support Figure 4–14b

Fibrocartilage Resists compression Figure 4–14c

Bone Also called osseous tissue: – Strong – resists shattering

Structures of Bone Figure 4–15

Bone Surface Periosteum: – covers bone surfaces – fibrous layer – Cambrium layer

Muscle Tissue

What are the structures and functions of the three types of muscle tissue?

Muscle Tissue Is specialized for contraction Produces all body movement

3 Types of Muscle Tissue Skeletal muscle: Cardiac muscle: Smooth muscle:

Classification of Muscle Cells Striation Pattern Number of Nuclei Nervous System Control

Skeletal Muscle Striated, voluntary, and multinucleated Figure 4–18a

Cardiac Muscle Tissue Striated, involuntary, and single nucleus Figure 4–18b

Smooth Muscle Tissue Nonstriated, involuntary, and single nucleus Figure 4–18c

Nervous Tissue

What is the basic structure and role of neural tissue?

Neural Tissue Also called nervous or nerve tissue: – Conduction – Sensation – Process – Control

Central Nervous System Neural tissue is concentrated in the central nervous system: – brain – spinal cord

2 Kinds of Neural Cells 1.Neurons: – nerve cells – perform electrical communication 2.Neuroglia: – support cells – repair and supply nutrients to neurons

Cell Parts of a Neuron Cell body: – contains the nucleus and nucleolus Dendrites: – short branches extending from the cell body – receive incoming signals

Cell Parts of a Neuron Axon (nerve fiber): – long, thin extension of the cell body – carries outgoing electrical signals to their destination

The Neuron Figure 4–19

Neuroglia Figure 4–19

Tissue Response to Injury

How do injuries affect tissues of the body?

Tissue Injuries and Repair Tissues respond to injuries to maintain homeostasis Cells restore homeostasis with 2 processes: – inflammation – regeneration

Inflammation Inflammation: Signs of inflammatory response include: – swelling – redness – heat – pain

Inflammatory Response Can be triggered by: – Trauma – Infection

The Process of Inflammation Damaged cells release chemical signals into the surrounding interstitial fluid: – prostaglandins – proteins – potassium ions

The Process of Inflammation As cells break down: – lysosomes release enzymes – that destroy the injured cell – and attack surrounding tissues

The Process of Inflammation Necrotic tissues and cellular debris (pus) accumulate in the wound: – abscess: pus trapped in an enclosed area

The Process of Inflammation Injury stimulates mast cells to release: – histamine – heparin – prostaglandins

The Process of Inflammation Dilation of blood vessels: – increases blood circulation in the area – causes warmth and redness – brings more nutrients and oxygen to the area – removes wastes

The Process of Inflammation Plasma diffuses into the area: – causing swelling and pain Phagocytic white blood cells: – clean up the area

Regeneration When the injury or infection is cleaned up: – healing (regeneration) begins

The Process of Regeneration Fibroblasts move into necrotic area: – lay down collagen fibers New cells migrate into area:

The Process of Regeneration Not all tissues can regenerate: – epithelia and connective tissues regenerate well – cardiac cells regenerate slowly and neurons do not regenerate

Summary: Inflammation and Regeneration Figure 4–20

SUMMARY Organization of specialized cells into tissues: – epithelial tissue – connective tissue – muscular tissue – nervous tissue

SUMMARY Division of epithelial tissues into epithelia and glands: – epithelia as avascular barriers for protection – glands as secretory structures

SUMMARY Attachments of epithelia to other cells and underlying tissues: – polarity (apical surface and basal lamina) – cell adhesion molecules (CAMs) – cell junctions (tight junctions, gap junctions and desmosomes)

SUMMARY Classification of epithelial cells: – by number of cell layers (simple or stratified) – by shape of cells (squamous, columnar or cuboidal)

SUMMARY Classification of epithelial glands: – by method of secretion (exocrine or endocrine) – by type of secretions (merocrine, apocrine, holocrine) – by organization (unicellular or multicellular) – by structure (related to branches and ducts)

SUMMARY The functions of connective tissues: – structure – transport – protection – support – connections – energy storage

SUMMARY The structure of connective tissues: – matrix – ground substance – protein fibers

SUMMARY The classification of connective tissues: – connective tissue proper (cell types, fiber types, and embryonic connective tissues) – fluid connective tissues (blood and lymph, fluid transport systems) – supporting connective tissues (cartilage and bone)

SUMMARY The 3 types of muscle tissues (skeletal, cardiac, and smooth) The classification of muscle tissues by striation, nucleation, and voluntary control

SUMMARY The 2 types of cells in neural tissue: – neurons and neuroglia The parts of a neuron (nerve cell): – cell body, dendrites, and axon (nerve fiber)

SUMMARY Tissue injuries and repair systems (inflammation and regeneration)