Histology: Tissue Types and Functions

Study Notes

Tissue Types and Functions

Epithelial tissue: Covers surfaces, lines cavities, forms glands
- Functions: secretion, absorption, protection, sensation, transport
Connective tissue: Provides support, protection, insulation, transport, storage
- Types: loose, dense, cartilage, bone, blood
Muscle tissue: Responsible for movement
- Types: cardiac, skeletal, smooth
Neural tissue: Communicates and processes information throughout the body
- Composed of neurons and glial cells

Histology Basics

Four primary tissue types: Epithelial, Connective, Muscle, Neural
Epithelial tissue polarity: Has apical and basal surfaces
Connective tissue characteristics: Variable composition of cells, fibers, and ground substance

Staining Techniques

Haematoxylin & Eosin (H&E): Most common stain
- Haematoxylin stains acidic components (e.g., nucleus)
- Eosin stains basic components (e.g., cytoplasm)
Giemsa stain: Stains both basic and acidic components
- Eosin and azure stains basic components
- Methylene blue stains acidic components

Identifying Tissues in Histological Slides

Observe overall structure: Determine if the tissue is organized in layers or is more scattered
Identify cell shapes: Look for squamous, cuboidal, or columnar shapes in epithelial tissues
Check for striations: Identify if muscle tissue is striated (skeletal and cardiac) or non-striated (smooth)
Look for specialized structures: Identify features like cilia or keratin in epithelial tissues
Assess the extracellular matrix: Evaluate the density and type of fibres present in connective tissues

Epithelial Tissue Structure

Apical surface: Exposed to the lumen
Basal surface: Rests on the basement membrane
Basement membrane: Thin layer that anchors epithelium to underlying connective tissue and provides structural support

Special Senses

Mechanoreceptors: Respond to mechanical pressure or distortion (touch, pressure, vibration)
Chemoreceptors: Respond to chemical stimuli (CO2, pH, organic/inorganic molecules)
Thermoreceptors: Respond to temperature changes (warm and cold sensations)
Nociceptors: Respond to pain stimuli (intense mechanical, thermal, or chemical stimuli)
Photoreceptors: Respond to light (rods for dim light, cones for color vision)

The Eye: Key Structures

Cornea: Transparent front part of the eye that refracts light
Lens: Focuses light onto the retina, changing shape for accommodation
Retina: Contains photoreceptors (rods and cones) that transduce light into electrical signals
Iris: Regulates the amount of light entering the eye by adjusting the size of the pupil

Eye Processes

Phototransduction: Photoreceptors convert light into electrical signals, involving breakdown of rhodopsin
Signal Transmission: Nerve impulses are transmitted across synapses using neurotransmitters

Fundamental Theories

Endogenous Activity: Organisms exhibit behavior based on internal processes
Stimulus-Response (SR) Model: Behavior is a direct response to stimuli, expanded upon in higher-order animals

Special Senses Facts

The human eye contains approximately 70% of all sensory receptors in the body.
The fovea is the area of greatest visual acuity in the retina.
Rhodopsin is the light-sensitive pigment in photoreceptors.
The optic chiasm is where the optic nerves partially decussate.
The suprachiasmatic nucleus is involved in circadian rhythms.

Description

Test your knowledge on the four primary tissue types: Epithelial, Connective, Muscle, and Neural. Explore their functions, characteristics, and common staining techniques in histology. This quiz will help reinforce your understanding of tissue structure and function.