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Chapter 4Tissues, Glands & Membranes

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Histology Is the study of body tissues

There are 4 ways body tissue is classified:

Epithelial TissueEpithelial Tissue – covers the surfaces of the body, lines cavities & forms glands

Connective TissueConnective Tissue – supports and forms the framework of all parts of the body

Muscle TissueMuscle Tissue – contracts and produces movement

Nervous TissueNervous Tissue – conducts nerve impulses

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Epithelial Tissue Forms a protective covering for the body &

all the organs

Example:

It is the main tissue of the outer layer of skin & it forms the lining of the intestinal tract, respiratory & urinary passages, blood vessels, the uterus & other body cavities

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Structure of Epithelial Tissue Epithelial tissue is classified according to its shape:

Squamous epithelial tissue is flat and irregular Cuboidal epithelial tissue is square Columnar epithelial tissue is long & narrow

Simple arrangement of cells is a single layer Stratified arrangement of cells is many layered

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Squamous Cells

Simple Squamous is a single layer of flat, irregular cells

Stratified squamous are many layered, flat, irregular cells

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1stQtr

2ndQtr

3rdQtr

4thQtr

East

West

North

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Cuboidal Cells

Simple cuboidal – single layer of square shaped cells

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Columnar Cells

Simple columnar – single layer of long, narrow cells

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What is Transitional Epithelium?

Because certain organs must vary a great deal in size during the course of their activities, they are composed of a specialized tissue called transitional epitheliumtransitional epithelium

This specialized tissue is capable of expanding and returning to its original form

Examples of epithelial tissue are: Urinary bladder > Uterus

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Functions of Epithelial Tissue

To produce secretions - Ex: mucous, perspiration & digestive juices

Absorption of digested food – done by special epithelium in the digestive tract

Trapping of dust and foreign particles in the passages of the respiratory system

Certain areas of the epithelium are capable of modifying themselves for greater strength – Ex: calluses

Reproduce frequently – Ex: skin, lining of the mouth & lining of the intestinal tract

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GlandsGlands – are organs specialized to produce a substance that is sent out to other parts of the body

Have many active cells made up of epithelial cells

Glands are divided into 2 categories:

1. Exocrine Glands2. Endocrine Glands

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Exocrine Glands Have DUCTS to carry secretions away from

the gland – either to a body cavity or another organ

Ex: digestive juices, oil glands of the skin called SEBACEOUS glands & tears from the LACRIMAL glands

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Endocrine Glands Depend on the blood that flows through a gland to

carry the secretion to another organ – these glands are DUCTLESS

These secretions are called HORMONES and have specific effects on tissues

Because they secrete directly into the bloodstream, they have an extensive blood vessel network – Ex: Adrenal Glands (near the kidneys) secrete epinephrine & adrenaline

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Connective Tissue Is the supporting fabric for all parts of the

body Has large amounts of non-living material

between the cells called MATRIX Matrix contains: water, fibers & hard

minerals There are 4 types of connective tissue

classified by the degree of hardness:

1. Soft 2. Liquid 3. Fibrous 4. Hard

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Soft Connective Tissue Loosely held together with a semi-liquid material

between cells Adipose (Fat) TissueAdipose (Fat) Tissue – contains cells capable of

storing large amounts of fat which are used as a reserve energy supply, serve as a heat insulator & a protective padding for organs and joints

Areolar (Loose) TissueAreolar (Loose) Tissue – the most common type in the body which contains cells & fibers in a loose, jelly-like material; found in membranes around vessels & organs, between muscles & under skin

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Liquid Connective Tissue Suspended in a fluid environment

Ex:

Blood

Lymph (fluid that circulates the lymphatic system)

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Fibrous Connective Tissue Densely packed tissue with fiber cells called

FIBROBLASTS Examples:

Collagen – flexible, white protein that is the main type of fiber found in connective tissue

Capsules – a particularly strong form that makes up the covering around certain organs: kidneys, liver & glands

Tendons – connect muscle to bone and the fibers all run in the same direction

Ligaments – connect bone to bone and the fibers all run in the same direction

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Repair of Fibrous Tissue Can repair itself easily Example:

Blood clots to form scabs to protect underlying tissue

From damaged capillaries, new vessels branch & grow to the injured tissue

Fibroblasts produce collagen & extensive growth of new tissue will form a scar

Excessive production of collagen may cause development of a KELOID

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What is Keloid Scarring?

Keloid scarring is a sharply raised area on the surface of the skin

Parts of the body susceptible to keloids are the deltoid region of the upper arm, the upper back, and the sternum. The earlobes and the back of the neck are common sites as well.

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Hard Connective Tissue Made up of a firm consistency or actually

hardened by minerals Examples:

Cartilage – used as a “shock absorber” and a bearing surface because of its strength and flexibility

Bone – made up of OSSEOUS tissue, it is much like cartilage in its cellular structure but becomes solid and hard with the addition of calcium & phosphorus

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Muscle Tissue Designed to produce movement by contraction of its cells

which are called MUSCLE FIBERS

Muscle tissue is not repaired easily, if at all, once an injury has been sustained

Muscle tissue is classified a follows:

1. Skeletal2. Cardiac3. Smooth

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Skeletal Muscle Works with tendons &

bones to move the body

Known as “voluntary” muscle

Moves or contracts by conscious thought

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Cardiac Muscle Forms the bulk of the

cardiac wall called the MYOCARDIUM

Produces the regular contractions of the heart

Known as “involuntary” muscle

Moves or contracts independently of conscious thought

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Smooth Muscle Also known as VISCERAL

muscle Forms the walls of the

VISCERA, which are the organs of the ventral body cavity – except the heart – includes: muscles of the digestive tract, walls of the blood vessels & tubes that carry urine from the kidneys

Also attached to the base of each body hair – contraction of these muscles cause the condition called “goose bumps”

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Nervous Tissue

Makes up the entire “communication” system of the brain, nerves and spinal cord

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Neurons Basic unit of nervous

tissue Consists of a nerve cell

body and fibers Dendrites carry

impulses TO the cell body

Axons carry impulses AWAY from the cell body

Axons are insulated & protected by the MYELIN SHEATH

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Membranes Thin sheets of tissue that can be fragile,

tough, transparent or opaque

Cover surfaces, serve as dividing partitions, line organs or anchor organs

May contain cells that secrete lubricants, such as in the joints

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Membranes & Disease A number of diseases directly affect

membranes:

The Common Cold: Inflammation of the nasal passages

Peritonitis: Infection of the peritoneum commonly follows the rupture of the appendix which can be fatal if not treated in time

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- Rheumatoid Arthritis – where the synovial membrane becomes inflamed and swollen affecting the cartilage in the joints

- Lupus – the serous membranes (pleura & pericardium) become inflamed, damaged and destroyed leading to a number of physical problems

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Membranes usually protect against the spread of infection, but in some cases, can also act as a pathway to spread disease

In general, when a person’s resistance is lowered, infection can spread

For example, a pregnant female can develop an infection in the tubes of the reproductive system which could travel into the placenta and affect the unborn child

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Benign & Malignant Tumors Any abnormal cell growth is called a TUMOR or

NEOPLASM

Benign tumors are typically confined to an area and do not spread

Malignant tumors spread to neighboring tissues or distant parts of the body

METASTASIS is the process of tumor cell spread

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Benign Tumors Although typically not life-threatening, they can be

harmful in certain cases, such as growing within an organ, increasing in size and causing damage to the organ

Types of benign tumors include: PapillomaPapilloma: grows in epithelium, such as a wart OsteomaOsteoma: originates in the bones MyomaMyoma: originates in muscle tissue; common mostly in

involuntary muscle, particularly in the uterus (Fibroid Tumors)

AngiomaAngioma: composed of small blood vessels; more commonly known as a birthmark

NevusNevus: skin tumors; better known as moles which are ordinarily harmless, but can become malignant

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Papilloma – a common wart

Mastoid Osteoma – tumor of the bone behind the ear

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Fibroid Tumor (Myoma)

Birthmark (Angioma)

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Mole (Nevus)

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Malignant Tumors Can cause death, no matter where they occur Send out “claw-like” extensions into

neighboring tissue Cancer cells travel to other body parts fairly

easy Secondary tumors form or METASTASIZE Grow more rapidly than benign tumors

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Carcinoma Most common form of cancer

Originates in the epithelium which includes: Skin Mouth Lung Breast Stomach Colon Prostate Uterus

**Usually spreads by the lymphatic system

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Sarcoma

Cancer of the connective tissue Can be found anywhere in the body Usually spreads by the bloodstream

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Gastric LymphomaA lymphoma is a malignant tumor that arises from the lymphoid cells in the body. They can occur almost anywhere in the body, including the stomach. In this instance, the tumor is present in the upper portion of the stomach and appears as an irregular ball. (Carcinoma)

Kaposi’s Sarcoma

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Cancer Symptoms Unusual bleeding or discharge Persistent indigestion Chronic cough Change in a mole Sore that doesn’t heal Presence of a lump Unexplained loss of weight

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Cancer Diagnosis Biopsy – removal of living tissue to examine cells

Ultrasound – high frequency sound waves to differentiate tissue

Computed Tomography (CT Scan) – cross sectional x-rays

Magnetic Resonance Imaging (MRI) – use of magnetic fields & radio waves to show changes in soft tissue

Blood Tests – screen the blood for key information; Example: Prostate Specific Antigen (PSA) test that screens for proteins produced in large quantities by prostate tumors

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Cancer Treatment Surgery – benign tumors are removed more easily.

Malignant tumor surgery could leave cancerous tissue behind. Laser surgery can destroy the tumor or cut the tumor in order to remove it.

Radiation – destroys rapidly dividing cells with small doses of radioactivity

Chemotherapy – drugs called ANTINEOPLASTIC AGENTS act selectively on cancer cells