Headings / Vocabulary / Important Information

Tissues

Headings / Vocabulary / Important Information

Terminology

•  Tissues – group of cells that carry out specialized activities

–  Histo = Tissue

–  …ology = study of

•  Pathologists – Study of cells and tissue; diseased

–  Patho = disease

Four Main Types

•  Epithelial

–  Body surfaces, hollow organs, glands

•  Connective

–  Binds organs together, energy reserves for fat

•  Muscle

–  Movement and force application

•  Nervous

–  Stimulates action potential to activate body functions

Germ Layers

•  Ectoderm – The primary layer which give rise to nervous system and the
epidermis of skin

•  Mesoderm – Middle germ layer which gives rise to connective tissue,
blood, muscles

•  Endoderm – Lower germ layer that gives rise to the GI tract, urinary
bladder, and respiratory tract

Junctions

•  Cell Junctions – Point of contact between adjacent membranes of various cell types

•  Tight Junctions -Fluid tight seal between cells to prevent leaking of substances into blood or surrounding tissues; stomach lining & urinary bladder, and intestines

•  Anchoring Junction (Desmosomes) – Fasten cells to on another, common in stretched areas such as heart, uterus, and outer skin

•  Gap Junction – Allow passage of chemical/electrical signals through connexons (protein tunnels-hollow cylinders) from cell to cell; i.e. muscular contraction, pain

EPITHELIAL TISSUE

·  Function: Protection, Filtration, Secretion, Absorption, and Excretion

·  Divisions:

1. Covering and Lining

2. Glandular Epithelium

Tissue Arrangements

Cell Shapes

I. EPITHELIAL TISSUE:
A.Squamous B.Cuboidal C.Columnar

A.Simple Squamous Epithelium

•  Function: Filtration, diffusion, osmosis, and secretion in serous membranes

•  Location: Kidneys Glomeruli (water, glucose, and wastes), Air Sac of Lungs (Gas Exchange), Heart and Blood Vessels (Nutrients & Medicine)

B.Simple Cuboidal Epithelium

•  Function: Secretion and Absorption

•  Location: Kidney Tubules (Wastes), Ovary
Surface (Ova)

C.”Ciliated” Simple Columnar Epithelium

•  Function: Moves fluids and particles along passageways

•  Location: Found in respiratory tract (mucosal Movement), fallopian tubes (Ova movement), sinuses (Pathogen removalà Runny Nose)

C.”Non-Ciliated” Simple Columnar Epithelium

•  Function: Microvilli secretion & Absorption

•  Location: GI tract lining (Absorption of nutrients and water) & Gallbladder (Secretion of Bile)

II. STRATIFIED EPITHELIUM:

A.Pseudostatified B.Squamous C.Cuboidal D.Columnar E.Transitional

A. Pseudostratified Ciliated Columnar Epithelium

•  Functions: Mucus movement by cilia action

•  Location: Found in upper respiratory tract and urethra, and
gonads of males (Sperm maturation)

B. Stratified Squamous Epithelium

•  Functions: Protection of superficial layers of skin; vagina, mouth, esophagus, tongue

•  Location:

–  Keratinized = Superficial Layers of Skin

–  Non-Keratinized =Wet Surfaces (Mouth, Vagina,Tongue)

C. Stratified Cuboidal Epithelium

•  Functions: Protection and limited secretion of sweat glands

•  Location: Sudoriferous Glands (SWEAT)

D. Transitional Epithelium

•  Function: Accommodate Distension in the urinary tract and vaginal walls as
fluid pressures vary.

–  Stretched = Squamous

–  Relaxed = Cuboidal

•  Location: Lining of the ureters, urethra, and bladder

III. GLANDULAR EPITHELIUM:

A. Glandular B. Exocrine

A. Endocrine Gland

•  Function: Produce hormones

•  Location: Thyroid, Pituitary Gland, Ovaries, Testicles

B. Exocrine Glands

–  Eccrine or Merocrine Secretion

•  Forms the product and discharge from the cell entirely

–  Salivary Glands

–  Apocrine secretion

•  Product forms at apical surface and pinches off from rest of cell

–  Mammary Gland

–  Holocrine Secretion

•  Accumulates secretory product in cytosol, cell dies and is discharge
with its product-Sebaceous Gland (Acne)

IV. CONNECTIVE TISSUE:

A. Bone B.Cartilage-i.Hyaline ii.Fibrocartilage iii.Elastic C.Dense Fibrous

D.Loose-i.Areolar ii.Adipose iii.Reticular E. Blood

Three basic characteristics:

1.  Cell Types

–  Fibroblasts – Large, flat immature cells responsible for mitosis & chemical
secretion of matrix cmpds

–  Macrophages – Fixed vs. Wandering = Local or systemic Phagocytosis
-Plasma Cells – Synthesis of B Lymphcoyte ~ Antibodies

–  Mast Cells – Histamine production, Heparin & Warfarin (Anticoagulants)

2.  Ground Substance (Matrix)

•  Hyaluronic Acid

–  Cell binding, wound healing

•  Chondroitin Sulfate

–  Adhesiveness for bone, cartilage

•  Dermatan Sulfate

–  skin, tendons, heart valves

•  Keratan Sulfate-Bone, Cartilage

3.  Fibers (Matrix)

·  Collagen – Strength for tissues, most abundant

·  Elastin – Elasticity of tissues up to 150% of normal size

A. BONE

Compact vs. Spongy

·  Provides for support

·  Movement-Marrow (blood-forming)

B. CARTILAGE

i.Hyaline, ii.Fibrocartilage, iii.Elastic

i. Hyaline Cartilage

·  Extremely strong, but very flexible and elastic

·  Smooth surface for reduction of friction

·  Movement of Joints, Flexibility,

·  Support (Trachea), Ossification

ii. Fibrocartilage

·  Extremely tough

·  Acts as a shock absorber, ball and socket joints

iii. Elastic Cartilage

•  Abundance of elastin for stretching capability

•  Nose, Ears, epiglottis, larynx

C. DENSE FIBROUS CONNECTIVE TISSUE

•  Dense, Closely packed collagen fibers that provide high tensile strength

•  Strong attachment for

•  Tendons (Muscle to Bone)

•  Ligaments (Bone to Bone)

D. LOOSE CONNECTIVE TISSUE

i.Areolar, ii.Adipose, iii.Reticular

i. Areolar Connective Tissue

•  Provides strength, elasticity, and support to
subcutaneous layer and papillary regions of skin

•  Consists of Collagen, Elastic, Reticular fibers

ii. Adipose Tissue

•  Fat (White):Used for insulation, energy reserve, fat storage

•  Fat (Brown): Generates body heat in newborns that do not shiver

•  After infants grow up, most of the
mitochondria (gives the brown color)
disappears, becomes similar to white fat.

•  Recent Research=brown fat is related not to
white fat, but to skeletal muscle

iii. Reticular Connective Tissue

•  Form covering of many internal organs (Stroma)-soft internal
skeleton that supports other cell types

E. BLOOD

•  Oxygen Transport

•  Clotting (platelets)

•  Immunity (WBC’s)

•  Nutrient delivery

V. MUSCLE TISSUE-A.Cardiac B.Skeletal C.Smooth

A. Cardiac Muscle

•  Composes the heart wall

•  Functions in pumping blood to all parts of the body

•  Intercalated discs contain Gap Junctions (Communication) & Desmosomes (Anchor)

B. Skeletal Muscle Tissue

•  Attached to bones by tendons

•  Functions in body movements, posture, thermogenesis

•  Only Muscle tissue controlled voluntarily

C. Smooth Muscle Tissue

•  Forms walls of many internal organs ie: Stomach, GI tract, Uterus, Anus

•  Functions in motion of internal organs

VI. Nervous Tissue

•  Consists of Neuron and Neuroglia

•  Neuron – Conversion from stimulus response to action potential (Sensory, Motor, Interneuron)

1.  Dendrites – Reacts to stimuli

2.  Axons – Conductor of impulse