Lecture #4: Histology

Histology

• Microscopic identification

• Study of cells and body

Tissue

Group of similar cells

Types of Tissues in the Body

1. Epithelial

2. Connective

3. Muscular

4. Nervous

Types of Epithelial Tissues

1. Squamous

2. Cuboidal

3. Columnar

Squamous Cells

• Flat cells (squashed)

• Rapid passages

Types of Squamous Cell

1. Simple Squamous

2. Stratified Squamous

Simple Squamous

• Alveoli

• Lining of heart and blood vessels

Types of Stratified Squamous

1. Keratinized (epidermis)

2. Non-keratinized (wet surfaces)

Stratified Squamous Epithelium Keratinized

Epidermis of the skin

Stratified Squamous Epithelium Non-Keratinized

• Mouth

• Esophagus

• V*gina (censored by knowt)

Cuboidal Cells

• cubed shape cells

• absorption and secretion

Transitional Cells

• Cuboidal to flat cells

• Lining of urinary bladder, urethra, ureters

Types of Cuboidal Cells

1. Simple Cuboidal

2. Stratified Cuboidal

Simple Cuboidal

• Endocrine glands

• Exocrine glands

Stratified Cuboidal

Ducts of sweat glands

Columnar Cells

• Taller than they are wide

• Often have microvilli and cilia (w/goblet cells)

• Secretion and absorption

Types of Columnar Cells

1. Simple Columnar Non-ciliated

2. Simple Columnar Ciliated

3. Pseudostratified Columnar

Simple Columnar Non-Ciliated Epithelium

Lining of GI tract

Simple Columnar Ciliated Epithelium

• Lines of trachea

• Fallopian Tubes

Pseudostratified Columnar Epithelium

• Upper respiratory tract

• ducts of most glands

Connective Tissue

• Embedded in extracellular matrix

• Ground substance

• Fibers

Types of Connective Tissue

1. Loose Fibrous

2. Dense Fibrous

3. Cartilage

4. Bone

5. Blood

6. Lymph

Loose Fibrous C.T.

• Supports

• Surrounds

• Cushions

Types of Loose Fibrous

1. Areolar C.T.

2. Reticular C.T.

3. Adipose

Areolar Connective Tissue

• Subcutaneous skin

• Mucous membranes

• Surround organs

Reticular Connective Tissue

Supports

• Liver

• Spleen

• Lymph Nodes

Adipose Tissue

• Subcutaneous Skin (liposuction)

• Surrounding heart kidneys

Types of Dense Fibrous C.T.

1. Regular

2. Irregular

Dense Regular C.T.

• Orderly Arrangements

• Tendons

• Ligaments

Dense Irregular C.T.

Dermis of Skin

Cartilage

• Chondrocytes

• Lacunae (Little lake)

• Joints: ear, nose, intervertebral discs

Types of Cartilage

1. Hyaline

2. Elastic

3. Fibro

Hyaline Cartilage

• Most abundant

• Weakest

• Joints, reduces friction, absorbs shock

Elastic Cartilage

• Elasticity

• Maintains shape

• External ear

Fibro Cartilage

• Strongest

• Intervertebral Discs

Types of Bone Tissue

1. Compact

2. Spongy

Compact Bone

• Osteon

• Lamellae

• Lacunae

• Canaliculi

• Haversian Canal

Osteon

• Looks like rings

Lamallae

Concntric circles of matrix

Lacunae

• Small spaces between lamallae

• Little lake

Osteocytes

Bone cells

Haversian Canal

Central canal which contains blood vessels and nerves

Spongy Bone

• Columns of trabeculae

• Red bone marrow

• No osteons

Blood Tissue

Largely composed of extracellular fluid called plasma

Erythrocytes

• Red blood cells

• Transports oxygen

Leukocytes

• White blood cells

• Fights infection and immunity

Thrombocytes

• Platelets

• Aids in blood clotting

Types of Muscles Tissue

1. Skeletal

2. Cardiac

3. Smooth

Skeletal Muscle Tissue

• Moves the bone

• Voluntary

• Striations

• Multiple Nuclei

• 2% mitochondria

Cardiac Muscle Tissue

• Heart

• Involuntary

• Branched striations

• One nucleus

• Intercalated Discs

• 35% mitochondria

Smooth Muscle Tissue

• Any organ that contract and relax

• Involuntary

• No Striations

• No pattern

• 2-10% mitochondria

Types of Nervous Tissue

1. Neurons

2. Neuroglial

Neurons

• Nerve impulses

• Dendrites (short branches)

• Axons (long single thin)

Neuroglial Cells

• Surround, support, insulate, and protect neurons

• No nerve impulses