CH. 4 TISSUES

PHYSIOLOGY

The Tissue Level of Organization

*Tissue-A group of similar cells sharing a common origin that are united to perform a particular function.

Also includes intercellular material, fluids, etc.

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• There are 4 primary types of tissue in the human body:
• 1. Epithelial
• 2. Connective
• 3. Muscle
• 4. Nervous

Epithelial Tissue

Covering and Lining

Glandular

Epithelial Tissue

General Characteristics:

• Little or no intercellular material between cells; composed of

cells that are packed close together.

• Has secretory, absorptive, and protective functions.
• Avascular-blood cells cannot penetrate between the cells.

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• Covers body surfaces, lines body cavities and organs, forms

glands, comprises the functional cells in some organs such as

liver and kidneys.

2 basic categories:

• Covering and Lining
• Glandular

Covering and Lining Epithelial Tissue

Covers external body surfaces and lines inner walls of body cavities and organs.

• 6 Types:
• Simple squamous
• Simple cuboidal
• Simple columnar
• Stratified squamous
• Pseudostratified columnar
• Transitional

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Simple Squamous Epithelial Tissue

*Flattened cells arranged in a

single layer.

Found where layers of cells must be thin to permit efficient diffusion of materials.

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Ex. Lines the insides of blood and lymphatic vessels, walls of tiny capillaries, walls of air sacs in the lungs, and linings of body cavities.

Simple Cuboidal Epithelial Tissue

*Cube-shaped cells in a single

layer. Often contain cilia or

microvilli along their free

border.

Commonly form the walls of small tubes or ducts that carry secretions from one region of the body to another.

EX. Found in kidneys, liver, and in glands.

Simple Columnar Epithelial Tissue

*Single layer of elongated,

cylindrical cells; nuclei are near

the basement membrane.

These cells frequently secrete a product, so their cytoplasm contains an abundance of rough endoplasmic reticulum and golgi apparatus.

Found lining the inside wall of the uterus and of the digestive organs such as the stomach and small intestine.

EX. In the small intestine the border has microvilli to help with the absorption of nutrients.

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Stratified Squamous Epithelial Tissue

*Multi-layered arrangement of cells that commonly covers areas of the body that must resist constant wear and tear.

The surface layer is squamous; deepest layers contain cuboidal or columnar cells that become flattened as they approach the surface.

EX. Makes up the outer layer of the skin and dips in at all openings of the body to protect them from abrasion.

Pseudostratified Columnar

*Appears multi-layered but isn’t; nuclei and cell shape lack uniformity.

Each cell contacts the basement membrane, but not all cells reach the surface.

Contain long cilia to create currents for movement of mucus (pseudostratified ciliated columnar epithelium).

EX. Lines parts of the respiratory tract such as the trachea and bronchi.

Transitional Epithelial Tissue

*Multi-layered arrangement of cells of cube-like or irregular shape; “crepe paper”

Individual cells have the properties of elasticity (stretch) and extensibility (return after being stretched).

EX. Lines the insides of organs that need elasticity such as the urinary bladder, ureters, etc.

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Glandular Epithelial Tissue�

*Closely packed cells that are highly specialized to manufacture and secrete products; called “glands”

• 2 types:
• Exocrine glands
• Endocrine glands

Exocrine Glands

*Empty products into ducts that transport product onto a body surface or into a body cavity.

EX. Sweat and oil glands in the skin, salivary glands, and single-celled mucous glands.

Endocrine Glands

*Empty products into extracellular space where products diffuse into the bloodstream.

EX. Pituitary gland at the base of the brain, thyroid gland in the neck, and the adrenal glands on each kidney all secrete hormones that diffuse into the blood.

CONNECTIVE TISSUE

Connective Tissue Proper

Cartilage

Bone

Blood-Forming Tissue and Blood

Connective Tissue

Review

• Intracellular-within the cell
• Extracellular-outside the plasma membrane
• Intercellular-area between cells

Connective Tissue�

Consists of a vast amount of intercellular material secreted by interspersed cells

Supports and protects body parts

Manufactures blood cells

Connective Tissue

General Characteristics:

Widely scattered cells that lie within a large amount of nonliving intercellular material.

The “glue” that keeps other tissues and organs in place.

Consists of two kinds of cells: one produces and maintains the intercellular material and other type protects tissue from infection.

Vascular-having the presence of blood vessels (necessary for growth and repair of tissue).

Intercellular Material for Connective Tissue

Composed of a mixture of sugar-protein molecules and interstitial fluid, which is known as ground substance, and several types of protein fibers.

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3 Types of Protein Fibers:

• Collagenous
• Elastic
• Reticular

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Protein Fibers in Connective Tissue

Collagenous-most abundant type of protein fiber; made of collagen, flexible but has great tensile strength (resists stretching); used for tissue repair (scar tissue).

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Elastic-made of elastin; not as strong as collagen; has elasticity and extensibility; not found in scar tissue.

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Reticular-composed of reticulin (resists physical stress despite branching shape; not abundantly found in connective tissue.

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Connective Tissue Proper

A group of connective tissues found throughout the body. There are 3 general groups that vary in the amount and types of fibers present.

Fibroblast-a cell that produces the intercellular material in connective tissue.

• 3 general groups:
• Loose (areolar)
• Adipose
• Dense

Loose Connective Tissue

The most widespread of all of the connective tissue.

Also called areolar tissue.

The intercellular material is composed of all 3 types of protein fibers (collagenous, elastic, and reticular) in a loose, disorganized network surrounded by a fluid forming a semi-fluid soft gel.

Loose Connective Tissue

Contains numerous fibroblasts and white blood cells (macrophages) which are particularly numerous during an infection.

Provides a structural anchor to body parts using its many layers.

Ex. Found between the skin and muscle layers, found on the surfaces of most organs, and fills in the spaces between organs and other body parts.

Loose (Areolar) Tissue

Adipose Tissue

Composed mainly of specialized fibroblasts called adipose cells or adipocytes that are large spherical cells containing fat.

Has minimal intercellular material with mostly reticular fibers.

Stores energy as fat.

Provides an insulating padding between organs.

Serves as a shock absorbing cushion.

Adipose Tissue

Dense Connective Tissue

Contains protein fibers that are packed closely together with little space in-between for other substances.

Contains fewer cells and more collagenous fibers than other types of connective tissue proper.

2 types:

Regular

Irregular

• Regular Dense Connective Tissue:

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• Irregular Dense Connective Tissue:

Dense Connective Tissue

REGULAR DENSE

Has densely packed fibers that extend parallel to one another.

Fibroblasts are distributed in a linear fashion beside the groups of fibers.

Extremely resistant to stress.

EX: Tendons and ligaments

IRREGULAR DENSE

Fibers are not in a parallel arrangement; instead they branch extensively to form a dense matting of protein.

Fibroblast are distributed randomly.

Found in the deep layer of the skin called the dermis.

Forms the external wrapping around bone and cartilage.

Tendon-Dense Regular Connective Tissue

Cartilage

Has a harder, more solid structure than connective tissue proper.

Contains dense, firm intercellular material composed of many protein fibers within a thickened, gel-like ground substance (matrix).

Matrix is maintained by cartilage cells (chondrocytes) that lie embedded within small chambers called lacunae.

Cartilage�

Surrounded by a vascular layer of dense irregular connective tissue called the perichondrium. Materials diffuse through this layer of tissue to nourish the chondrocytes.

3 Types of Cartilage:

Hyaline

Elastic

Fibrocartilage

Hyaline Cartilage

Bluish white in color, almost opaque.

The most abundant type of cartilage in the body.

Matrix dominated by chondroitin sulfate.

Chondrocytes are embedded in lacunae and are sparsely distributed throughout the matrix.

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Hyaline Cartilage

Found in the upper portion of the respiratory tract, at the ends of bones in movable joints, and at the ends of ribs.

Also forms most of the skeleton of a fetus and precedes bone formation in most bones of a growing child.

Elastic Cartilage

Yellowish in color.

Elastic fibers dominate the matrix.

Firm, but flexible.

Matrix has chondroitin sulfate, but it doesn’t dominate.

Forms the supportive framework for the ears, end of nose, and the epiglottis.

Elastic Cartilage

Fibrocartilage

• Solid, but flexible matrix.
• Matrix has a predominance of thick collagenous fibers.
• Found with hyaline cartilage in joints like the knee, where it serves as a shock absorber.
• Also found in the intervertebral discs where it pads the joints between vertebrae.

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Bone

• Intercellular material is filled with mineral salts and collagenous fibers that give it a hard durable structure.
• Intercellular material (matrix) is maintained by bone cells called osteocytes which lie embedded in lacunae.
• Osteocytes obtain nourishment by diffusion from blood vessels that penetrate through the hard matrix.
• These blood vessels originate in the membrane that surrounds bone called the periosteum.
• 2 Types of Bone:

Compact

Spongy

Two Kinds of Bone: Compact & Spongy

Compact Bone

• Has a densely packed matrix with deposits of mineral salts and collagen.
• Nourishment is provided by way of blood vessels that extend through bone in canals called osteonic canals or haversion canals.
• The osteonic canals are surrounded by thin layers of matrix call lamellae that form concentric circles around the osteonic canals.

Compact Bone

• Nutrients diffuse across the lamellae by way of tiny channels called canaliculi.
• In the outer layers there are no osteonic canals and lamellae form a solid matrix.
• Each osteonic canal + concentric lamellae + osteocytes inside lacunae = osteon or a haversion system.

Compact Bone

• Osteons cemented together by other types of lamellae form compact bone which covers the surface of all the bones in the body.

Spongy Bone

• Matrix is not so densely packed; contains spaces or holes that are filled with red marrow, which is blood-forming tissue.
• The hard region of the matrix contains mineral salts and collagen to form spicules.
• Spicules create an irregular network full of spaces

filled with marrow.

• Oseocytes with the lacunae are in spicules.
• Found making up the interiors of bones.

Blood-Forming Tissue and Blood

• Blood forming tissue (BFT) manufactures the cellular component of blood.
• Blood-forming tissue is the softest tissue in the body because it lacks collagen and mineral salts.
• 3 components of BFT:

Stem cells-produce blood cells

Newly formed blood cells in the process of maturing

A small amount of protein

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Blood-Forming Tissue

RED MARROW

• Found in spongy bone.
• Called hematopoietic tissue.
• Initiates the production of blood cells such as platelets, red blood cells, and white blood cells.

LYMPHOID TISSUE

• Found in the lymph nodes, tonsils, spleen, and thymus in children.
• Maturation site for two kinds of blood cells, monocytes and lymphocytes.

BFT

RED MARROW

LYMPHOID TISSUE

Blood

• The transport vehicle for the cardiovascular system.
• Carries respiratory gases, nutrients, and cellular waste.
• 2 Components of Blood:

Formed elements

Plasma

Blood

FORMED ELEMENTS

• Red blood cells
• White blood cells
• Platelets

PLASMA

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• Fluid matrix with dissolved protein molecules that you see in clotting.
• Mostly water.

Muscle Tissue

Skeletal

Smooth (Visceral)

Cardiac

Muscle Tissue

Closely arranged cells with little intercellular material.

Proteins in cells enable contraction to occur which results in movement.

3 Types of Muscle Tissue:

Skeletal

Smooth (Visceral)

Cardiac

Skeletal Muscle

Attached to bones

The primary tissue of the muscular system.

Tendons attach skeletal muscle tissue to bones; tendons are bands of dense regular connective tissue.

Located deep under the skin layer.

Contracts under voluntary control.

Functions to produce body movement.

Appears striated (with alternated dark and light bands).

Smooth Muscle

Also known as visceral.

Forms part of the walls of blood vessels and visceral organs such as the stomach, intestines, bladder, and uterus.

Contract to propel substances through its tubes and chambers.

The contractions are involuntary.

Does not appear to be striated (no light and dark bands).

Cardiac Muscle

Also known as Myocardium.

Found in the walls of the heart.

Has coordinated contractions that push blood out of the heart and through the body.

Contractions are involuntary.

Cells DO CONTAIN STRIATIONS.

Intercalated disks-The name given to the thickened plasma membrane between cardiac cells that help to conduct electrical impulses.

Nervous Tissue

Nervous Tissue

Sends and carries electrochemical signals through the body.

Has well-developed properties of conductivity and excitability.

2 Types of Cells

Neurons-highly specialized cells that conduct electrochemical signals very rapidly.

Neuroglia-maintain and support the neurons; numerous in brain & spinal cord.

Neurons & Types of Neuroglia

Membranes

A simple combination of tissues that include connective tissues and, in most cases, epithelial tissue to form a thin sheeting; the simplest combination of tissues to form a functional unit.

Membranes

Also may contain blood vessels, lymphatic vessels, and nerves.

Structurally divides areas of the body or organs.

Lines the internal surfaces of hollow organs and body cavities.

Anchors organs to other structures.

Provides and support and protection for body structures that transport substances throughout the body.

Membranes

EPITHELIAL

Contains both connective and epithelial tissue.

• Mucous
• Serous
• Cutaneous

SYNOVIAL

Contains only connective tissue; no epithelial tissue.

Epithelial Membranes

Mucous Membranes

Lines passageways leading to the outside of the body.

Lines the internal walls of the digestive tract from the mouth to the anus; also lines the internal walls of the respiratory tract from the nasal cavity to the alveoli.

Lines the ureters, bladder, and urethra.

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Epithelial Membranes

Mucous Membranes (cont’d)

Lines organs of the reproductive tract.

Secretes mucous to trap foreign particles, maintains a moist internal environment, and protect cells from harmful liquids such as acid and urine.

Epithelial Membranes

Serous Membranes

Line body cavities and cover certain organs.

Lines internal surfaces of thoracic and abdominopelvic cavities and organs within these cavities.

Secretes clear, watery fluid that helps with lubrication.

EX. Pericardium (surrounds the heart), the 2 pleurae (surround each lung), and the peritoneum (lines the abdominal cavity and organs located there).

Epithelial Membranes�

Cutaneous Membrane

Constitutes the skin.

Primary organ of the integumentary system.

Epithelial Membranes

Synovial Membranes

Lines the cavities of joints.

Found in the joints of the knee, elbow, and shoulder.

Secretes synovial fluid that lubricates opposing bones of the joint as they move.

Nourishes cartilage at the ends of bones with oxygen and nutrients.

Synovial Membranes

Tissues, Tumors, and Cancer

Tumor (neoplasm)-an overgrowth of cells that form a tissue that has no useful purpose to the body.

Tumors are harmful when they replace healthy and compete with surrounding tissue for nutrients, oxygen, etc.

Tumors are caused by mutations in the DNA of a cell. Most mutations are caused by exposure to environmental agents, called carcinogens.

Some mutations can be caused by a virus.

Tumors

There are 2 major types of tumors:

• Benign
• Malignant

Benign Tumors-grow slowly and remain localized.

Malignant Tumors-grow rapidly and infiltrate into surrounding tissues, often spreading (metastasis) into lymphatic and blood vessels that can transport them to distant sites in the body.

Types of Malignant Tumors (Cancers)

Carcinomas-Arise from epithelial tissue (EX. Breast and lung cancer)

Sarcomas-Arise from connective tissue; rapidly spreading (EX. Bone cancer)

Leukemias-Arise from blood-forming tissues; blood cells cannot perform normal functions.

Membranes and Immunological Diseases

Membranes are often the first structure to be affected by an infectious agent, and may serve as pathways for the spread of disease, since they are widespread, interconnected, and vascular.

The usual response to an infection is inflammation.

Inflammation

Results in edema.

Edema is swollen membranes caused by the accumulation of fluids and white blood cells in the affected area.

Results in swelling, pain, excessive mucus, swollen passageways, increased friction.

EX. Common cold-excessive discharge of mucus and swollen passages, pleurisy-inhibition of secretion of serous fluid surrounding lungs resulting in friction and pain due to rubbing, edema in a synovial membrane results in enlargement of the joint cavity.

Inflammatory Response Mechanism