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Lecture 3
Histology
Study of Tissues
Introduction
 A tissues is a mass of similar cells and cell products that forms a discrete
______________ of an organ and performs a specific function
 A matrix is material that surrounds the cells, and is composed of fibrous
proteins and ground substance
 Tissue differences:
 Types and _____________ of the cells
 Characteristic of the matrix (extracellular material) that surrounds
the cells
 Relative amount of space occupied by cells versus ____________
Primary Tissue Classes
 Epithelial Tissue
o Epithelium is a type of tissue composed of one or more layers of closely
adhering cells, either covering an organ surface or forming the secretory
tissue and ducts of a ________________
 It’s found in the linings of organs, the lining of body cavities, and
forms the __________________of the skin
 The extracellular material is so thin that there is no room for blood
vessels, so they rely on blood vessels in loose connective tissue for
nourishment
 Anchoring the epithelium to the connective tissue below is a layer
of tissue called the _____________________ membrane
 Surfaces of epithelium that face the basement membrane
are basal surfaces
 Surfaces that face away from the basement membrane are
__________________ surfaces
 Types of Epithelium:
 Simple – having only a ___________________ layer of cells
 Simple squamous – single layer of flat, scale-like cells
o Found in air sacs of lungs, glomerular capsules of kidneys
o Allows rapid _______________ or transport through
membranes
 Simple cuboidal – single layer of cube-shaped (though perhaps
rounded) cells
o Found in the liver, thyroid, many glands
o For absorption and ___________________
 Simple columnar – single layer of cells that are taller than they
are wide – greater volume allows more absorption & secretion
o Found in lining of stomach, intestines, uterus
o Absorption, secretion of ________________
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
o Simple ______________ columnar epithelium has cilia to
move the egg through the uterine tubes
 Pseudostratified columnar – Epithelium that has the appearance
of having multiple layers (stratified), but which actually has a
single layer of cells that are not all the same height
o Found in ___________________ tract
o Secretes and propels mucus
 This tissue has cilia to move mucus and dust
 Stratified – having _______ or more layers of cells, with some
cells resting on others, rather than being in direct contact with the
basement membrane
 Stratified squamous – multiple layers of flat, scale-like cells
o Actually, not all of the cells in this tissue will necessarily
appear flattened. The tissue type is named for the flattened
cells that appear at the __________________
o There are two kinds of stratified squamous epithelium, one
containing the protein keratin, and the other without
 Keratinized stratified squamous epithelium is found on
the skin surface and resists water loss and provides
resistance to _____________ penetration
o Found in the epidermis
o Resists abrasion, penetration, water loss
 Nonkeratinized stratified squamous epithelium provides a
surface that is abrasion resistant, but also moist and
slippery
o Found in the ______________, esophagus, vagina
o Resists abrasion and penetration by pathogens
 Stratified cuboidal – multiple layers of cube-shaped cells
o Found in sweat gland ducts, in ovaries and testes
o Contributes to sweat, secretes hormones, produces sperm
 Stratified columnar – multiple layers of cells that are taller than
they are wide
o Rare, found only in parts of the pharynx, anal canal,
______________
 Transitional epithelium – multiple layers of cells that were
once thought to represent a transitional stage between
squamous and columnar
o Found in the urinary bladder and part of the urethra
o Stretches to allow _________________ of urinary tract
Connective Tissue
o Functions:
 __________________ of organs – tendons bind muscle to bone,
ligaments bind bone to bone, fat holds the kidneys in place, etc.
 Also support, protection, movement, storage, heat production,
transport
o Components:
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o
Cells
 Fibroblasts – Large flat cells that appear tapered at the ends and
produce the fibers and ground substance that form the
________________ of the tissue
 Macrophages – Large phagocytic cells that engulf and destroy
bacteria, foreign matter, or dead and dying cells
 _______________________ – White blood cells that react against
bacteria, toxins, and other foreign agents
 Mast cells – Cells found along blood vessels that secrete heparin or
histamine to inhibit blood clotting or increase blood flow
 Adipocytes – Fat cells
o
Fibers
 Collagenous fibers – Tough, flexible fibers, made of collagen
 Reticular fibers – Thin collagen fibers coated with glycoprotein,
forming a spongelike network
 Elastic fibers – Fibers composed of a protein called
____________, which has a coiled structure that allows it to
stretch and recoil like a rubber band
 Ground substance – Three classes of large molecules that form a
gel in connective tissue that slowes down the spread of bacteria
and other pathogens. They also bind tissue components together.
o Fibrous connective tissue
 Loose connective tissue – Much space is occupied by ground
substance
 Areolar tissue – has fibers that run in random directions and
has highly variable appearance
 It ______________ blood vessels and nerves,
allowing passage through other tissues
 Provides space for immune defense, and provides
nutrients and waste removal for overlying epithelia
 Reticular tissue – has a mesh-like appearance and forms the
structural framework of the lymph nodes, spleen, thymus,
and bone marrow
 Adipose tissue – tissue in which adipocytes are the
dominant cell type
 It stores energy and provides cushioning
 Dense connective tissue – ________________ take up more space
than cells or ground substance
 Dense regular connective tissue
 Has fibers that are closely packed and the fibers run
_______________________ to the direction of
force (such as in ligaments and tendons)
 Binds muscle to bone and bone to bone
 Dense irregular connective tissue
 Has thick bundles of collagen which run in
_________________ directions
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

It binds skin to muscle and withstands stress
in unpredictable directions
o Cartilage – supportive connective tissue with a flexible rubbery matrix
 Hyaline Cartilage – Found in the trachea and over the ends of
______________ at movable joints
 It holds the airway open and eases joint movement
 Elastic Cartilage – Fount in the external ear and nose
 It provides flexible, elastic support
 Fibrocartilage – Fount in the pubic symphysis and between the
bones of the ___________________ column
 It withstands compression and absorbs shock
o Bone
 Spongy bone is bone tissue that fills the heads of the long bones.
 It is made up of many long delicate slivers that give it a
_____________ appearance
 Compact bone is bone tissue that forms the surface of skeleton.
 It is more dense calcified tissue, with no spaces visible to
the naked eye
o Blood
 Plasma is the ground substance part of the blood (the liquid part)
 Formed elements are cells and cell fragments that carry oxygen,
fight infection, or help to form _____________ if an injury occurs
Nervous and Muscular Tissue
o Nervous Tissue is tissue specialized for rapid communication by means of
electrical and chemical signals
 Neurons are specialized cells that detect stimuli and transmit
information __________________ to other cells
 Soma – cell body that houses the nucleus and other
organelles
 Dendrites – processes extending from the cell body that
___________________ signals from other cells
 Axons – processes (1 for each neuron) that send outgoing
signals from the soma
 Glial cells – cells that support and assist the neurons
o Muscular Tissue is tissue that is specialized to contract when stimulated
(thus exerting physical force on other tissues)
 Skeletal muscle –
 Long cylindrical cells, with visible _________________
and multiple nuclei per cell
 Muscles attached to bones, but also muscles controlling
voluntary sphincters
 Used for body movements, breathing, speech, and other
voluntary control
 Cardiac muscle
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

Short branched cells connected by
_____________________ discs and having only one
nucleus per cell
 Found in the heart
 Used for pumping blood (involuntary)
 Smooth muscle
 Short fusiform (spindle-shaped) cells, each with one
nucleus and no striations
 Found as sheets of tissue in the walls of internal organs, or
as part of sphincters of the urethra and anus
 Used for movement of ___________through the GI tract or
urine through the urinary system, etc. that are involuntarily
controlled
Glands and Membranes
o Glands are organs or cells that secrete substances for use in the body or for
elimination from the body
 Cells vs organs
 Single-celled glands – ______________ cells are shaped
somewhat like a wineglass, and are found in the epithelia of
many mucous membranes
 Multicellular glands – include all other glands in which
multiple cells work together to produce secretions
 Exocrine glands are glands that convey their secretions through
_______________ to the surface of the body or to the lumen
(cavity) of another organ
 Endocrine glands secrete their products directly into the
bloodstream for transport to __________________ cells
 Types of secretions
 Serous glands produce relatively thin, watery fluids, such
as perspiration, milk, or tears
 Mucous glands produce a glycoprotein called
______________, which absorbs water to form mucus
(note the different spelling)
 Mixed glands contain both serous and mucous cells and
produce a mixture of the two types of secretions
 Cytogenic glands release whole cells (sperm or egg cells)
 Methods of secretion
 Merocrine glands release their secretions by exocytosis
(only the secretion is released from the gland)
 ______________________ glands accumulate products
within the cell and then the entire cell disintegrates, so that the
substance released is a mixture of product and cell fragments
 Apocrine glands were named when it was believed that bits
of apical cytoplasm broke away from the cell surface.
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Technically this isn’t true, but there are differences between
these glands and merocrine glands.
o Membranes
 Cutaneous membranes – ______________
 Stratified squamous epithelium resting on a layer of
connective tissue
 Mucous membranes – membranes that line passageways leading to
the exterior
 Digestive, respiratory, and reproductive tracts
 Serous membranes – membranes that produce watery serous fluid
 Line the insides of some body cavities and form a smooth
surface on the outer surface of some viscera
 Endothelium – Simple squamous epithelium that lines the lumens
of the blood vessels, heart, and lymphatic vessels
 Synovial membranes – Membranes made of connective tissue that
span the gap from bone to bone and secrete slippery
_________________ fluid into the joint

Tissue Growth and Repair
o Growth
 Hyperplasia – growth through cell multiplication
 ___________________- enlargement of existing cells
o Repair
 Regeneration - Replacement of cells by the same type of cells
 Fibrosis – Replacement of damaged tissue with ____________
tissue, composed mainly of collagen