CELLS & TISSUESChapter 3 – Pgs. 59-70

Tissue – group of cells working together to perform a specific function

Histology – the study of tissues Four groups of tissues:

Epithelial – Table 3-6 Connective – Table 3-7 Muscle – Table 3-8 Nerve – Table 3-8

Epithelial

Found of the surfaces as covering (skin) or on inner surfaces as lining (digestive tract); many types are capable of secretion (sweat, saliva, digestive enzymes)Epithelial cells are classified

according to shape and arrangement of cells – fig. 3-7

Shapesquamous – flat, scale likecuboidal – cube shapedcolumnar – tall and narrow

Arrangementsimple – single layer of cells of the same shapestratified - many layers of cells of the same shapetransitional – several layers of cells with different shapes

Simple Squamous – important in the exchange of materials or for absorption; found in capillaries, alveoli (air sacs) – Fig. 3-8

makes up epidermis of skin where surface cells are dead (keratinized)

lining of mouth, esophagus, and vagina where surface cells are alive (non-keratinized)

function in protection and barrier for microorganisms

Stratified squamous epithelium – Fig. 3-9

Keratinized stratified squamous epithelium

Non keratinized stratified squamous epithelium

Simple Columnar Epithelial – Fig. 3-10

Single layer of cells taller than wide linings of stomach, intestines, and

respiratory tract specialized cells called goblet cells

secrete mucus regular cells specialize in absorption

Simple Cuboidal (glandular epithelium) – Fig. 3-8, 3-12

single layer of cube-shaped cells function in secretory activity glands; cluster or groups of secretory

cells exocrine – release secretions into ducts (ex.

Salivary glands) endocrine – release secretions directly into

bloodstream (ex. Thyroid gland)

Stratified Transitional Epithelium – Fig. 3-11

surface cells change shape from cuboidal to squamous

found in areas exposed to stress and need to be able to stretch (ex. Urinary bladder)

Pseudostratified epithelium (ciliated)

columnar cells that have cilia and look as if there are two cell layers

cilia sweeps mucus trapped dust and bacteria protecting lungs

lines nasal cavities, trachea, and bronchial tubes

also lines fallopian tubes (oviducts) and sweeps ovum from ovary to uterus

Connective Tissue

Most abundant tissue type, most varied, common to all is the presence of a matrix in addition to cells – matrix is a structural network or solution of non-living intracellular material (ex. Blood matrix is plasma, bone matrix is calcium salts)

Aereola (loose connective tissue) most widely distributed connective tissue

 cells are called fibroblasts which produce protein fibers (collagen and elastin)

Protein fibers and tissue fluid makeup matrix

found beneath epithelial tissues and body systems that have an opening to the environment for protection against microorganisms

functions as “glue” that gives form to internal organs and protection

Adipose – Fig. 3-13

cells are called adipocytes matrix consists of tissue fluid and some

collagen fibers function – storage of lipids/cushion for

organs

Fibrous Connective Tissue – Fig. 3-14

consists mainly of parallel collagen fibers

strong but flexible makes up tendons and ligamentstendon – connects muscle to bone

ligament – connects bone to bone

relatively poor blood supply, slow to heal

Bone – Fig. 3-15

cells are called osteocytes matrix is made of calcium salts and collagen – strong, hard, not flexible

osteocytes, matrix, and blood vessels are arranged in Haversian system

functions – calcium storage, support body, protect internal organs

Cartilage – Fig. 3-16

cells called chondrocytes found on surfaces of joints to prevent

friction found in ear, tip of nose, wall of

trachea, and in between vertebrae function – prevent friction, absorbs

shock, permits movement no capillaries, gets nourishment

through diffusion from surrounding tissues

Blood – Fig. 3-17

Matrix is blood plasma plasma contains dissolved salts, nutrients,

and waste products function of plasma – transportation of

material around the body cells of blood

red blood cells carry oxygen white blood cells destroy pathogens – principle component of the immune system

platelets – prevent blood loss through clotting

Red blood cell

WhiteBloodcell

Platelet

Hemopoietic Tissue

found in red marrow cavities of bone, spleen, tonsils, and lymph nodes

function in formation of blood cells – important in defense against disease

This tissue is a complex mixture of different cell types and a rich lattice

Replacement of bone marrow fat with dark red hemopoietic tissue

Muscle – specialized for contraction, when muscles contract they shorten and bring about some type of movement

Skeletal Muscle (striated or voluntary muscle) – Fig. 3-18

cylindrical, have several nuclei/cell appear striated b/c of precise

arrangement of contracting proteins in cells

muscles are attached to bones and move skeleton

voluntary in movement, respond to nerve stimuli from brain

Smooth Muscle (visceral or involuntary) – Fig. 3-20

long, narrow, single nuclei/cell, no striation

involuntary form walls of blood vessels, and

organs such as stomach and intestines

help regulate diameter of blood vessels and propels food down digestive tract

Cardiac Muscle (myocardium) – Fig. 3-19

branched, interlocking muscle, faintly striated, 1 nuclei/cell

form walls of chambers of the heart function – pump blood, maintain blood

pressure contract by themselves and therefore

maintain “one” beat nerve impulses from nervous system

function to increase or decrease beat as dictated by certain situations

Nerve Tissue – Fig. 3-21 cells are called neurons, supporting cells are

neuroglia function – transmit electrochemical impulses structure of neuron

cell body – contains nucleusaxon – carries impulses away from cell bodydendrite – carries impulses toward cell body

each neuron has several dendrites that branch in different direction

impulses are transmitted from one neuron to another at the synaptic cleft by chemical messengers called neurotransmitters

make up brain, spinal cord, and nerves function – sensation, movements, regulation of

body functions, organization of information for learning and memory