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Systems of Support, Protection, Movement

• Integumentary System (Skin)

  • Provides protection and acts as a selective barrier to the outside world.

  • Binds the body together.

  • Protects from bacteria and other harmful agents.

• Skeletal System

  • Hard and rigid, offering protection to internal organs.

  • Provides structural support.

• Muscular System

  • Facilitates movement of the body.

Systems of Internal Communication & Integration

• Nervous System

  • Comprises the brain, spinal cord, and peripheral nerves.

  • Functions as a high-speed communication system to the body, helping to sense internal and external stimuli and make decisions based on them.

• Endocrine System

  • Communicates via hormones, chemical signals that act as messengers in the body.

Systems of Fluid Transport

• Circulatory System

  • Composed of the heart, blood, and blood vessels.

  • Divided into two parts: Cardiovascular System (transports hormones, oxygen, and nutrients) and Lymphatic System (play a vital role in immune function).

Systems of Intake & Output

• Respiratory System

  • Consists of the nasal cavity, pharynx, lungs, and trachea.

  • Responsible for oxygen intake and carbon dioxide removal, maintaining blood pH levels.

• Digestive System

  • Involves the oral cavity, teeth, esophagus, stomach, and intestines.

  • Functions to intake, break down, absorb nutrients and water.

• Urinary System

  • Eliminates metabolic waste via kidneys that produce urine, ureters, and urinary bladder.

  • Critical for regulating blood volume and pressure.

Tissues

• Definition:

  • Tissue is a group of closely associated cells that are similar in type and structure and perform common functions.

• Extracellular Matrix (ECM):

  • Composed of ground substance (varies in consistency) and fibers (structural proteins).

Primary Tissue Types

1. Epithelial Tissue:

   • Covers and lines surfaces inside and outside the body.

2. Connective Tissue:

   • Supports, binds, and transports substances.

3. Muscle Tissue:

   • Specialized for movement.

4. Nervous Tissue:

   • Responsible for communication and processing information.

Epithelial Tissue Characteristics

• Tightly packed cells with high cellularity.

• Avascular (lack of blood vessels) but innervated (has nerves).

• High regenerative capacity (rapid cell division).

• Supported by connective tissue.

Types of Epithelial Tissue

Classification by Layers:

• Simple: Single layer.

• Stratified: Multiple layers.

• Pseudostratified: Appears layered but is a single layer.

Classification by Shape:

• Squamous: Flat cells.

• Cuboidal: Cube-shaped cells.

• Columnar: Taller than they are wide.

Epithelial Functions

• Protection: Acts as a barrier against pathogens and physical damage.

• Absorption/Secretion: Allows for selective permeability.

• Sensory Reception: Contains receptors for sensations like smell.

Connective Tissue

• The most diverse tissue in the body with various functions:

  • Support: Provides a framework for the body.

  • Binding: Connects different body parts and holds organs in position.

  • Protection: Shields internal organs.

  • Immune Defense: Acts against pathogens.

  • Transport: Blood as a connective tissue transports nutrients and waste.

  • Energy Storage: Stores energy in the form of fat.

Types of Connective Tissue

1. Fibrous Connective Tissue:

   • Loose CT or Dense CT.

2. Cartilage:

   • Hyaline, Fibrocartilage, Elastic.

3. Bone (Osseous Tissue):

   • Hard, calcified matrix providing support and protection.

4. Blood:

   • Fluid connective tissue transporting substances throughout the body.

Glands

• Structures made of epithelial tissue that produce and secrete chemicals:

  • Endocrine Glands: Secrete hormones directly into the bloodstream (no ducts).

  • Exocrine Glands: Secrete substances through ducts (e.g., sweat glands).

The Integumentary System

• Comprises skin, glands, hair, and nails.

• Functions of Skin:

  • Provides protection, maintains water balance, synthesizes vitamin D, allows sensation, regulates temperature, and facilitates communication.

• Layers of Skin:

  • Epidermis: Outer layer with multiple regions.

  • Dermis: Deep connective tissue containing glands and follicles.

  • Hypodermis: Composed of fat and connective tissue, serving as insulation and energy storage.

Skeletal System

• Functions to support the body, enable movement, and protect internal organs.

• Bone Structure:

  • Composed of collagen and mineral matrix with primary cells like osteoblasts and osteocytes.

• Types of Bones:

  • Long, short, flat, and irregular bones with varying functions.

  • Key features include diaphysis (shaft), epiphysis (ends), and medullary cavity (inner space).