Chapter 4 - Histology

Histology

study of tissue

4 Major Tissues

Epithelial, Connective, Muscle, Nervous

Epithelial Tissue Characteristics

• covers internal and external surfaces

• little extracellular material

• lines body cavities and hollow organs

• basement membrane

What is included in free surface? (Epithelial)

Microvili

Cilia

Smooth (no friction)

Why does Epithelial Tissue lack blood vessels?

Because we lose cells very quickly (skin)

Divide rapidly → Heal rapidly

Epithelial Functions

• protective barrier & permit substance to pass

• secretion, absorption & protection

Simple Epithelial Tissue

a single layer of cells (absorption)

Stratified Epithelial Tissue

more than one layer of cells (protection)

Cell Shapes in Epithelial Tissue

Squamous, Cuboidal, Columnar

Simple Squamous Epithelium

• allows absorption

• Location: air sacs (O2), walls of capillary

Simple Cuboidal Epithelium

• secretion and absorption

• Location: kidney tubules, ovary

Simple Columnar Epithelium

• secretion and absorption

• if absorption = microvilli (surface area)

• Location: intestines

• goblet cells

• secrete mucus

Pseudo-stratified Columnar Epithelium

• NOT stratified

• has cilia

• many goblet cells (mucus out of airway)

• Location: respiratory system, glands

Stratified Squamous Epithelium

• protection

• Location: skin, oral cavity, vagina

Stratified Cuboidal Epithelium

• 2 or 3 layers of cells

• protection, ABSORPTION, and secretion

• Location: sweat and salivary glands

Stratified Columnar Epithelium

• protection and secretion

• Location: mammary ducts, male urethra

Transitional Epithelium

• tissue stretch, cells change shape

• Location: lining of urinary bladder

Define Glands

group ofe cells that are specialized to produce and secrete substances mostly in epithelial tissue

Exocrine Glands

• ducts

• secrete substances onto an INTERNAL or EXTERNAL surface

Endocrine Gland

• no ducts

• secret substances INTO tissue fluid or blood hormones

Connective Tissue

has extracellular matrix to separate cells from one another

Collagenous Fibers (protein)

• thick threads of collagen

• flexible but not stretchy

Reticular fiber (protein)

supports tissue

Elastic fibers

• composed of elastin

• stretch then resume back to original shape (vocal cords)

Ground Substance

Fluid

Functions fo Connective Tissue

• separates tissues/organs

• connects tissues (tendons and ligaments)

• framework

• stores compounds

• cushion and insulate

• transports

• protects

blast

produce

cyte

maintain

clast

break down

Fibroblasts

PRODUCES connective fibers

• ex: collagen, reticular, elastic

Mast Cells

• near blood cells

• release heparin (prevent blood clotting)

• releases histamine (react to allergies and promote inflammation)

Macrophages

• large WBC

• carries phagocytosis (cell-eating) to eliminate foreign substances

Areolar Tissue

• collagen and elastic fibers separated

• forms thin membranes

• Location: skin to underlying organs, fills spaces between muscles, glands and nerves

Adipose Tissue

• happens when cells store lipid in the cytoplasm for energy

• cell sites get numerous → forms adipose

• functions: cushion joints, insulates, stores energy

• Location: between muscle, around kidneys and heart

Dense Connective Tissue

• has many dense packed fibers

• slow healing because INDIRECT blood supply

Dense Connective Tissue

• mostly collagen

• very strong

• Location: tendon and ligaments

Dense Elastic Connective Tissue

• mostly elastic

• stretch/recoil

• Location: vocal cords

Cartilage

• has chondrocytes (cartilage cells)

• Function: support, allows attachment, protects

• indirect blood supply

Hyaline Cartilage

• covers ends of bones

• rings in respiratory tract (vacuum hose)

• costal cartilage (sternum to ribs)

Fibrocartilage

• pads between vertebrae

• shock absorber

• Location: knee joints, jaw

Elastic Cartilage

Location: external ears, epiglottis, auditory tube (hearing), larynx (voice box), 

Bone Tissue

• osetocytes (bone cells)

• lot of collagen (strong)

• Function: support/protects

• muscle attachment

• forms blood cells

• direct blood supply/heals fast

Blood

liquid matrix and maintain homeostasis

Skeletal Muscle

• Attaches muscle to bone

• Voluntary

• Has Striations

• Many Nuclei

Smooth Muscle

• In internal hollow organs, bladder, blood vessels

• Involuntary

• No striations and individual cells

Cardiac Muscle

• In the heart

• Involuntary

• Intercalated disc

Characteristics of Nervous Tissue

a. Neurons

b. Neurolgial cells

External Membranes

cutaneous membrane (skin)

Internal Membrane

1. Mucous membrane - lines openings to the outside of the body (digestive, respiratory, reproductive) and protects, absorbs, and secretes

2. Serous Membranes

Synovial Membrane

lines cavities with synovial fluid for lubrication for moveable joints

5 Symptoms of Tissue Damage

heat, tenderness, redness, swelling, and pain

Onset of Inflammation

1. Blood vessels to dilate (heat and redness)

2. Increase permeability of blood vessels (swelling)

Tissue Repair

Regeneration - new cells of the same type are generated

Replacement

New tissue develops and may cause scarring