Chap 39 SM23

Page 1: Learning Objectives and Key Terminology

Learning Objectives

• Understand and define the following key biological terms:

  1. Tissues, organs, and systems

  2. Basic characteristics of epithelial tissue

  3. Two major types of epithelial tissues and membranes

  4. Classification of epithelia by cell shape and layers

  5. Structure, function, and location of major types of connective tissue

  6. Homeostasis vs. homostasis and feedback cycles

  7. Distinction between conformer and regulator

  8. Negative vs. positive feedback cycles

  9. 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

1. Epithelial

2. Connective

3. Muscle

4. 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

1. Connective tissue proper.

2. Supporting connective tissue.

3. 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

1. Hyaline: Supports and reduces friction (e.g., rib cage).

2. Elastic: Provides flexibility (e.g., epiglottis).

3. 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).

Page 22:

(No content provided)