Chap 39 SM23
Page 1: Learning Objectives and Key Terminology
Learning Objectives
Understand and define the following key biological terms:
Tissues, organs, and systems
Basic characteristics of epithelial tissue
Two major types of epithelial tissues and membranes
Classification of epithelia by cell shape and layers
Structure, function, and location of major types of connective tissue
Homeostasis vs. homostasis and feedback cycles
Distinction between conformer and regulator
Negative vs. positive feedback cycles
Ectotherms vs. endotherms, acclimatization, and torpor
New Terminology
Collagen fibers: Tough proteins providing strength to tissues.
Columnar: Tall, narrow epithelial cells.
Conformer: Organism that adapts its internal environment to match the external one.
Cuboidal: Square-shaped epithelial cells.
Ectotherm: Organism that relies on external heat sources.
Elastic fiber: Fibers that can stretch and return to original form.
Endotherm: Organism generating internal heat.
Homeostasis: Maintenance of stable internal conditions.
Homostasis: Maintenance of constant, unchanging conditions.
Mucous membrane: Epithelial tissue that secretes mucus.
Negative feedback: Response counteracting stress.
Positive feedback: Response enhancing direction of stress.
Page 2: Distinction of Biological Structures
Tissues
Definition: Groups of similar cells working together for specific functions.
Organs
Definition: Combinations of different tissues working together for a common purpose.
Organ Systems
Definition: Related organs working together.
Total of 11 organ systems in humans.
Major Animal Tissues
Epithelial
Connective
Muscle
Nervous
Page 3: Characteristics of Epithelial Tissue
Epithelial Tissue Characteristics
Comprised of continuous sheets attached to a basement membrane.
Acts as a barrier regulating substance exchange.
Functions: protection, absorption, secretion, sensation.
Epithelial Cell Contacts
Tight junctions: Highly regulated passage.
Desmosomes: Hold cells together.
Gap junctions: Allow passage between cells.
Epithelial Polarity
Asymmetry in membranes (different proteins/lipids) influences function.
Page 4: Types of Glands and Membranes
Epithelial Glands
Exocrine: Release hormones externally through ducts.
Endocrine: Release hormones directly into surrounding fluids.
Epithelial Membranes
Mucous Membrane (Mucosa): Lines the body cavities open to the outside.
Serous Membrane (Serosa): Lines internal body cavities, secreting serous fluid.
Page 5: Classification of Epithelia
Between Cell Shapes and Layers
Squamous: Rapid diffusion (thin, flat).
Cuboidal: Short cylinder-like.
Columnar: Tall, with potential cilia for movement.
Simple: Single layer of cells.
Stratified: Multiple layers of cells.
Page 6: Simple Squamous and Cuboidal Epithelia
Simple Squamous Epithelium
Description: Thin, flat cells.
Function: Rapid diffusion.
Locations: Glomerulus (kidneys), alveoli (lungs).
Simple Cuboidal Epithelium
Description: Single layer of cube-shaped cells.
Function: Secretion and absorption.
Location: Kidney tubules.
Page 7: Simple Columnar Epithelium
Types of Simple Columnar Epithelium
Non-ciliated: For absorption/secretion; found in stomach and intestines.
Ciliated: Propels materials; found in uterine tubes.
Page 8: Stratified Epithelia
Stratified Squamous Epithelium
Description: Multiple layers of flat cells.
Function: Protection against abrasion.
Types: Keratinized (dry, skin) vs. Non-keratinized (moist, mouth, esophagus).
Stratified Cuboidal Epithelium
Description: Multiple layers of cube-shaped cells.
Function: Secretion.
Locations: Ducts of larger glands.
Page 9: Additional Stratified Types
Stratified Columnar Epithelium
Description: More than one layer of columnar cells.
Function: Protection and secretion.
Locations: Male urethra, mammary glands.
Pseudostratified Epithelium
Description: Appears layered but is not; cells attached to basement membrane.
Types: Ciliated (trachea) vs Non-ciliated (male reproductive tract).
Page 10: Transitional Epithelium
Description and Location
Appearance: Cuboidal/columnar at base, squamous at surface.
Function: Stretching.
Locations: Bladder, ureters.
Page 11: Connective Tissues Overview
Functions
Bind, support, protect, insulate, and transport materials.
Structure
Comprised of cells and extracellular matrix (ground substance).
Types of Connective Tissue
Connective tissue proper.
Supporting connective tissue.
Fluid connective tissue.
Page 12: Fiber Types in Connective Tissue
Collagen Fibers
Tough, provide strength and resist stretching.
Elastic Fibers
Composed of elastin, return to original form after stretching.
Reticular Fibers
Thin fibers supporting tissue structure.
Page 13: Types of Loose Connective Tissue
Areolar Connective Tissue
Function: Cushions and supports; fluid reservoir.
Adipose Tissue
Function: Energy storage, insulation, and cushioning.
Page 14: Reticular Connective Tissue
Description and Function
Provides internal framework for organs and supports other tissues.
Locations: Liver, spleen, lymph nodes.
Page 15: Dense Connective Tissue
Types of Dense Tissue
Dense Regular: Parallel collagen fibers for strength in specific directions (e.g., tendons).
Dense Irregular: Collagen fibers arranged irregularly for multi-directional strength (e.g., dermis).
Elastic Connective: Elastic fibers allowing structures to return to shape post-expansion.
Page 16: Supporting Connective Tissue: Cartilage
Overview
Comprised of chondrocytes in a matrix, cartilage is crucial for structural support.
Types of Cartilage
Hyaline: Supports and reduces friction (e.g., rib cage).
Elastic: Provides flexibility (e.g., epiglottis).
Fibrocartilage: Resilient and shock-absorbing (e.g., vertebral discs).
Page 17: Functions and Locations of Hyaline and Elastic Cartilage
Hyaline Cartilage
Function: Support, reduces friction.
Location: Ends of long bones, rib cage.
Elastic Cartilage
Function: Flexibility and support.
Page 18: Fibrocartilage
Overview
Function: Resists compression and absorbs shock.
Locations: Vertebral discs, pubic symphysis.
Page 19: Feedback Systems
Homeostasis vs. Homostasis
Homeostasis: Adaptive change in response to internal/external conditions.
Homostasis: Maintenance of fixed, stable internal environments.
Components of Feedback Cycle
Stressor: Disruption in homeostasis.
Receptor, Integrator, Effector: Roles in responding to stressor.
Page 20: Feedback Cycles
Negative Feedback
Response counteracts stressors to maintain balance.
Positive Feedback
Response intensifies or enhances the change from the stressor.
Page 21: Thermoregulation and Organisms
Ectotherms
Organisms dependent on external heat to regulate temperature.
Endotherms
Organisms that generate body heat through metabolism.
Acclimatization
Adjustment over time to changes in environment.
Torpor
Physiological state reducing metabolic rates (e.g., hibernation).
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