Download cells

Chapter 4 The Tissue Level of
Organization
BIO 210 Lab
Instructor Dr. Rebecca Clarke
Tissue
 Histology = study of tissues
 Tissue = group of cells that perform specific, limited
functions
Composition of Tissues
 Basic components
 Cells
 Matrix
 Surrounds cells
 Consists of
 Ground substance
 Protein fibers or proteins
4 Major Groups of Tissues
 Epithelial tissue
 Connective tissue
 Muscle tissue
 Neural tissue
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  movement
Neural Tissue
 Carries electrical signals (nerve impulses) from one part of
the body to another
Epithelial Tissue
 Includes
 Epithelia = layers of cells that cover
 External/exposed surfaces (skin)
 Internal surfaces that line internal passageways and cavities
 Glands = cellular structures that produce secretions; are
attached to or derived from epithelia
Classes of Epithelia
 Based on cell shape and layers
Table 4–1
Simple Squamous Epithelium
Figure 4–3a
Stratified Squamous Epithelium
Figure 4–3b
Simple Cuboidal Epithelium
Figure 4–4a
Stratified Cuboidal Epithelium
Figure 4–4b
Transitional Epithelium
Figure 4–4c
Simple Columnar Epithelium
Figure 4–5a
Stratified Columnar Epithelium
Figure 4–5c
Pseudostratified
Columnar Epithelium
Figure 4–5b
Glandular Epithelia
 Endocrine and exocrine glands
 Range from scattered cells to
complex organs (glands)
Figure 4–6
Endocrine Glands
 Ductless glands
 Release secretions (hormones) into interstitial fluid or blood
 Regulate/coordinate activities of many tissues, organs, organ
systems
Exocrine Glands
 Release secretions
 onto epithelial surfaces, e.g., simplest = one-cell goblet cell (in
respiratory and digestive tracts)
 through ducts, e.g., sweat, digestive, lacrimal, mammary glands
What are the structures
and functions of different types of
connective tissues?
Characteristics of
Connective Tissues
 Fills internal spaces
 Many diverse functions
 Many highly-specialized cells
 Much more matrix than cells
Components of Connective
Tissue
 Cells – highly varied, specialized populations
 Matrix
 Consists of
 Ground substance



Fills spaces between cells and surrounds connective tissue fibers
Clear, colorless, amorphous substance; changes according to tissue
Viscous (“syrupy”) due to proteoglycans and glycoproteins
 Protein fibers/proteins
 Can be fluid, gel or solid, e.g., gelatin dessert
 Determines specialized function
Classification of
Connective Tissues
 Connective tissue proper
 Connects and protects
 Loose and dense connective tissues
 Fluid connective tissues
 Transport systems
 Blood and lymph
 Supporting connective tissues
 Structural strength
 Cartilage and bone
Connective Tissue Proper
Figure 4–8
8 Cell Types of
Connective Tissue Proper
 Mesenchymal cells
 Mast cells
 Fibroblasts
 Adipocytes
 Phagocytes
 Macrophages
 Microphages
 Melanocytes
 Lymphocytes
Mesenchymal Cells
 Mesenchyme = first connective tissue in developing
embryo (see text Fig 4-9)
 Are connective tissue stem cells; give rise to all other
connective tissue cells
 e.g., Respond to local injury/infection by dividing 
daughter cells that differentiate into other connective
tissue cells, e.g., fibroblasts, macrophages, etc.
Fibroblasts
 “Fiber builder”
 Most abundant cell type
 Found in all connective tissue proper
 Secrete
 polysaccharide (+ protein  proteoglycans  viscous ground
substance)
 protein subunits  large fibers
Phagocytes
 Phagocytes (“cell eaters”)
 Macrophages (“big eaters”)
 Microphages (“little eaters”)
Macrophages
 Large, amoeba-like cells of the immune system
 Eat pathogens and damaged cells; “garbage disposal” cells
 Release chemicals that activate immune system 
mobilizes body defenses
 2 classes
 fixed macrophages stay in tissue; frontline defense
 free macrophages migrate through tissues; reinforcements
Microphages
(NOT in Fig 4-8)


Phagocytic white blood cells (WBCs), i.e., neutrophils and
eosinophils
Attracted to site of infection/injury by chemicals released
by macrophages
Mast Cells
 Small mobile cells
 Stimulate inflammation after injury or infection
 Cytoplasm filled with granules that contain/release histamine
and heparin
 Basophils are mast cells carried by blood
Adipocytes
 Adipose or fat cells
 Store fat
 Contain single, large lipid droplet; nucleus, other organelles,
cytoplasm squeezed to side  class ring appearance
 Number of cells varies with tissue, body region, individual
Melanocytes
 Synthesize, store melanin (brown pigment)  dark color
 Common in skin epithelium
 Determine skin, eye, hair color
Lymphocytes
 Specialized immune cells in lymphatic system
 e.g., plasma cells that produce antibodies; one of body’s defense
mechanisms
 WBCs that leave bloodstream and migrate throughout body
 Numbers increase with tissue damage
Protein Fibers
 Provide structural strength to connective tissues
 3 types
 Collagen
 Reticular
 Elastic
Collagen Fibers
 Most common fibers
 Large, long, straight, unbranched
 Strong, flexible (like rope); very little stretch
 Predominate in ligaments (connect bone to bone) and
tendons (connect muscle to bone)
Reticular Fibers
 Same protein subunits as collagen but
 Thinner, shorter
 Arranged differently  branched network of interwoven
fibers (stroma)
 Strong, flexible
 Stabilizes functional cells of organs (parenchyma), e.g.,
hepatic cells of liver
 Stabilizes position of blood vessels, nerves, etc.
 Connects epithelium to body
Elastic Fibers
 Contain protein elastin
 Branched and wavy
 Return to original length after stretching
 e.g., elastic ligaments of vertebrae
Categories of
Connective Tissue Proper
 Loose connective tissue
 more ground substance, less fibers
 e.g., fat (adipose tissue)
 Dense connective tissue
 more fibers, less ground substance
 e.g., tendons
Loose Connective Tissue
 Few soft fibers  loose, open framework; “packing
materials” of body
 Fills spaces between organs
 Cushions, stabilizes cells
 Supports epithelia, blood vessels, nerves
Loose Connective Tissue (cont.)
 3 types
 Areolar tissue
 Adipose tissue
 Reticular tissue
Areolar Tissue
 Least specialized
 Open framework of cells/fibers
 Can distort, return to original shape because of elastic
fibers
 Most of volume is viscous ground substance
 Highly vascular, e.g., subcutaneous layer under skin,
common injection site
Fig 4-8
Adipose Tissue
 Primarily adipocytes (adipose cells)
Figure 4–10a
Adipose Cells
 Adipocytes in adults do not divide
 expand to store fat
 shrink as fats are released
 Mesenchymal cells divide and differentiate
 to produce more fat cells
 when more storage is needed
Reticular Tissue
 Primarily reticular fibers
Figure 4–10b
Reticular Tissue
 Complex, 3-dimensional network
 Supportive fibers (stroma)
 support functional cells (parenchyma)
 Reticular organs
 spleen, liver, lymph nodes, and bone marrow
Dense Connective Tissues
 Tightly packed with high numbers of collagen or elastic
fibers
 Many fibroblasts
 Very strong tissues
 Types of dense connective tissues
 dense regular connective tissue
 dense irregular connective tissue
 elastic tissue
Dense Regular Connective Tissue
 Tightly packed, parallel collagen fibers
 Make up tendons, ligaments, aponeuroses
Figure 4–11a
Dense Regular Connective Tissues
 Tendons - attach skeletal muscles to bones
 Ligaments - connect bone to bone and stabilize organs
 Aponeuroses - attach in sheets on large, flat muscles
Dense Irregular Connective Tissue
 Strength in many directions
Figure 4–11b
Dense Irregular Connective Tissues
 Interwoven meshwork of collagen fibers
 layered in skin
 around cartilages (perichondrium)
 around bones (periosteum)
 form capsules around some organs (e.g., liver, kidneys, spleen)
Elastic Tissue
 Made of elastic fibers
 e.g., elastic ligaments of spinal vertebrae
Figure 4–11c
Fluid Connective Tissues
 Blood and lymph
 Cells suspended in fluid matrix = watery ground substance
with dissolved proteins
Blood Formed Elements
 RBCs (erythrocytes)
 WBCs (leukocytes)
 Platelets
Figure 4–12
Lymph
 Cells – 99% lymphocytes, rest are macrophages or microphages
 Matrix = fluid from CVS exits at capillaries  interstitial fluid 
enters lymphatic vessels (= lymph) that return it to CVS
(recirculatory system)
 Along way, cells of immune system monitor composition of lymph
and respond to signs of injury or infection
 Essential to homeostasis – eliminates local differences in nutrients,
wastes, toxins, maintains blood volume, alerts immune system
Fluid Tissue Transport Systems
 Cardiovascular system (blood)
 arteries
 capillaries
 veins
 Lymphatic system (lymph)
 lymphatic vessels
Supporting Connective Tissues
 Support soft tissues and body weight
 Cartilage
 for shock absorption and protection
 Bone
 for weight support
Supporting Connective Tissues
 Characteristics
 Provide strong framework that supports body
 Cells – less diverse than CT
 Matrix
 Dense ground substance
 Cartilage – rubbery, gel-like
 Bone - calcified, crystalline, solid matrix
 Many fibers
Cartilage Components
 Cells
 Chondrocytes = only cells present
 Occupy lacunae (small chambers)
 Matrix
 Ground substance = firm gel with…
 Chondroitin sulfates (polysaccharide derivatives); form
complexes with proteins  proteoglycans
 Protein fibers
 Type and number + proteoglycans determine physical
properties
Cartilage Structure
 Avascular = no blood vessels
 chondrocytes produce antiangiogenesis factor
 Perichondrium
 surrounds cartilage and separates it from tissue
Types of Cartilage
 Hyaline cartilage
 translucent matrix
 no prominent fibers
 Elastic cartilage
 tightly packed elastic fibers
 Fibrocartilage
 very dense collagen fibers
Hyaline Cartilage
Figure 4–14a
Hyaline Cartilage
 Most common
 Matrix - contains closely packed collagen fibers 
tough, flexible support
 Reduces friction between bones
 Examples




Connects ribs and sternum
Nasal cartilages
Cartilages that support respiratory passageways, e.g., trachea
Articular cartilages – cover bone surfaces within synovial joints,
e.g., elbow, knee; reduce friction
Elastic Cartilage
Figure 4–14b
Elastic Cartilage
 Many elastic fibers  resilient, flexible structures; supports
but bends easily
 Examples
 auricle/pinna of outer ear
 epiglottis (in larynx)
 auditory tube (airway to middle ear)
 small cartilages in larynx
Fibrocartilage
Figure 4–14c
Fibrocartilage
 Very little ground substance
 Matrix dominated by densely interwoven collagen fibers
 extremely durable, tough
 Resists compression
 Acts as shock absorber
 Prevents bone-to-bone contact
 Examples:
 Intervertebral discs = pads between vertebrae
 Between pubic bones
 Pads knee joints
Bone
 Also called osseous tissue
 Osteocyte = bone cell
 Arranged around central canal
 Small channels through matrix (canaliculi) access blood supply
 Periosteum
 covers bone surface
 Helps attach bone to surrounding tissues, tendons, ligaments
Bone
Figure 4–15
Bone Ground Substance
 Very small amount of ground substance
 2/3 of matrix is calcium salts (minerals) = hydroxyapatite
 Calcium phosphate
 Calcium carbonate
 1/3 of matrix dominated by collagen fibers
 Minerals organized around collagen fibers
  Remarkable properties of bone
 Strong (calcified salts) + somewhat flexible structure (collagen fibers)
 Highly resistant to shattering (like steel-reinforced concrete
 mineralized matrix like concrete
 collagen fibers equiv to steel reinforcing rods
Comparing Cartilage
and Bone
Table 4–2
What are the structures
and functions of the three
types of muscle tissue?
Muscle Tissue






Specialized for contraction; produces all body movement
Distinct organelles and processes
Multinuclear
Has many fibers; orderly appearance
under voluntary or involuntary control
One of two kinds of cells/tissues in body that stop
replicating past stage of growth and development; (other
is neural tissues/neurons)
3 Types of Muscle Tissue
 Skeletal muscle - large body muscles responsible for
movement
 Cardiac muscle - found only in the heart
 Smooth muscle - found in walls of hollow, contracting organs
(blood vessels; urinary bladder; respiratory, digestive and
reproductive tracts)
Classification of Muscle Cells
 Striated (muscle cells with a banded appearance)
 or nonstriated (not banded)
 Single nucleus
 or multinucleate
 Controlled voluntarily (consciously)
 or involuntarily (automatically)
Skeletal Muscle
 Striated, voluntary, multinucleated
Figure 4–18a
Skeletal Muscle Cells
 Very long (some > 1 ft) and thin; called muscle fibers
 Multinucleate; 100s of nuclei/cell
 Cytoskeleton contains actin and myosin filaments
 Filaments organized into repeating groups  striated/banded
appearance
 Contract when stimulated by nerves; provide voluntary control over
muscle activities
 Adjacent muscle fibers connected by collagen and elastic fibers that
blend into attached tendon or aponeurosis; when contract, pull on
attached bone, producing movement
 Can’t divide; new muscle fibers produced through divisions of
satellite (stem) cells; can partially repair after injury
Cardiac Muscle Tissue
 Striated, involuntary, single nucleus
Figure 4–18b
Cardiac Muscle Cells
 Cardiac muscle cell = cardiocyte
 Smaller than skeletal muscle cell
 Usually one centrally positioned nucleus
 Actin and myosin filaments arranged in same way as in skeletal muscle;  striations
 Cells form branching networks; connected at specialized regions = intercalated




discs (like dovetail joints)
Ion movement through gap junctions helps coordinate contractions throughout
heart
Rely on pacemaker cells to establish regular rate of contraction; neural
stimulation not required
Involuntary muscle contractions
Very limited ability to repair
Smooth Muscle Tissue
 Nonstriated, involuntary, single nucleus
Figure 4–18c
Smooth Muscle Cells
 Smooth muscle cell
 small, spindle-shaped cell, tapered ends
 single oval nucleus
 actin and myosin filaments organized differently from those of skeletal and cardiac
muscles, no striations  “smooth” appearance
 Nervous system does not provide voluntary control over contractions; hence,
smooth muscle = involuntary muscle
 Cells can divide and regenerate after injury
 Location:
 Walls of blood vessels
 Around hollow organs, e.g., urinary bladder
 In layers around respiratory, circulatory, digestive, reproductive tracts
What is the basic structure and
role of neural tissue?
Neural (Nervous) Tissue
 Specialized for conducting electrical impulses
 Rapidly senses internal or external environment
 Processes information and controls responses
Neural Tissue
 98% concentrated in central nervous system (CNS)
 brain
 spinal cord
 Remaining 2% in peripheral nervous system (PNS)
2 Types of Neural Cells
Neurons
1.


nerve cells
perform electrical communication
Neuroglia
2.


support cells
repair and supply nutrients to neurons
Neuron
Figure 4–19
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
Characteristics of Neurons
 Longest cells in body – some > 1 meter
 Cannot divide under normal circumstances so very limited
ability to repair selves
 One of only two kinds of cells/tissues in body that stop
replicating after stage of growth and development (other is
muscle tissue)
Neuroglia
Figure 4–19