Study Guide – Chapter 4: Tissues (The Living Fabric)
Why It Matters
● Tissues = groups of specialized cells working to maintain homeostasis.
● Understanding tissues helps monitor injury and disease (e.g., bedsores, cancer).
● Four primary types:
1. Epithelial – covers/lines surfaces, forms glands.
2. Connective – supports, protects, binds, transports.
3. Muscle – movement.
4. Nervous – control/communication.
4.1 Microscopy Basics
● Preparation: fixed (preserved), sectioned (sliced), stained (contrast).
● Light microscopy = dyes; electron microscopy = metal coatings.
4.2 Epithelial Tissue
Definition: Sheet of cells covering surfaces or lining cavities; forms glands.
Functions: Protection, absorption, filtration, secretion, excretion, sensory reception.
Key Characteristics
1. Polarity – apical (free) vs basal (attached to basal lamina).
2. Specialized contacts – tight junctions, desmosomes.
3. Supported by connective tissue – via basement membrane.
4. Avascular but innervated – nutrients diffuse in; nerves present.
5. Regeneration – rapid repair due to friction/damage.
Clinical: Cancerous cells can invade past basement membrane.
Classification
● By layers:
○ Simple = 1 layer (absorption, filtration, secretion).
○ Stratified = multiple layers (protection).
● By shape:
○ Squamous (flat), cuboidal (cube), columnar (tall).
Major Types
● Simple squamous – diffusion/filtration (lungs, kidney); special cases = endothelium
(vessels) & mesothelium (serous membranes).
● Simple cuboidal – secretion/absorption (kidney tubules).
● Simple columnar – absorption/secretion (digestive tract).
● Pseudostratified columnar – secretion/mucus movement (respiratory tract).
Why It Matters
● Tissues = groups of specialized cells working to maintain homeostasis.
● Understanding tissues helps monitor injury and disease (e.g., bedsores, cancer).
● Four primary types:
1. Epithelial – covers/lines surfaces, forms glands.
2. Connective – supports, protects, binds, transports.
3. Muscle – movement.
4. Nervous – control/communication.
4.1 Microscopy Basics
● Preparation: fixed (preserved), sectioned (sliced), stained (contrast).
● Light microscopy = dyes; electron microscopy = metal coatings.
4.2 Epithelial Tissue
Definition: Sheet of cells covering surfaces or lining cavities; forms glands.
Functions: Protection, absorption, filtration, secretion, excretion, sensory reception.
Key Characteristics
1. Polarity – apical (free) vs basal (attached to basal lamina).
2. Specialized contacts – tight junctions, desmosomes.
3. Supported by connective tissue – via basement membrane.
4. Avascular but innervated – nutrients diffuse in; nerves present.
5. Regeneration – rapid repair due to friction/damage.
Clinical: Cancerous cells can invade past basement membrane.
Classification
● By layers:
○ Simple = 1 layer (absorption, filtration, secretion).
○ Stratified = multiple layers (protection).
● By shape:
○ Squamous (flat), cuboidal (cube), columnar (tall).
Major Types
● Simple squamous – diffusion/filtration (lungs, kidney); special cases = endothelium
(vessels) & mesothelium (serous membranes).
● Simple cuboidal – secretion/absorption (kidney tubules).
● Simple columnar – absorption/secretion (digestive tract).
● Pseudostratified columnar – secretion/mucus movement (respiratory tract).
