Physiology & Pathophysiology

Introduction to Physiology

Physiology is the study of how the body and its systems function. It focuses on the mechanisms that keep organisms alive and healthy.

• Physiology: "How does it work?" Study of normal functioning.

• Pathophysiology: Study of abnormal diseases or malfunction.

• Gross (macroscopic) anatomy: Study of structures visible to the naked eye.

• Microscopic anatomy: Study of structures requiring magnification (e.g., histology ).

Levels of Organization

Hierarchical Structure of the Human Body

The human body is organized into increasingly complex levels, each building upon the previous.

• 1. Chemical Level: Atoms combine to form molecules.

• 2. Cellular Level: Molecules combine to form cells, the basic unit of life.

• 3. Tissue Level: Similar cells work together to perform a specific function.

• 4. Organ Level: Two or more tissues work together to form organs.

• 5. Organ System Level: Organs work together to perform complex functions.

• 6. Organism Level: All organ systems working together (e.g., human body).

Major Organ Systems

Each organ system has specific functions vital to survival.

Positions & Terms

Body Orientation and Directional Terms

Standard anatomical terms are used to describe locations and relationships of body parts.

• Anterior/Posterior: Front/back

• Superior/Inferior: Above/below

• Medial/Lateral: Toward/away from midline

• Proximal/Distal: Closer/farther from point of attachment

• Superficial/Deep: Toward/away from body surface

Body Cavities: Physical spaces (cranial, thoracic, abdominal, pelvic) containing organs.

Chemistry in the Human Body

Main Elements and Molecules

The human body is composed primarily of a few key elements and molecules.

• Main elements: Oxygen, Carbon, Hydrogen, Nitrogen

• Water: Most abundant molecule in the body

• Electrolytes: Ions such as Na+, K+, Ca2+, Cl- are essential for cellular function

Homeostasis & Regulation

Definition and Importance

Homeostasis is the process by which the body maintains a stable internal environment despite external changes.

• Homeostasis: Maintains equilibrium (e.g., temperature, pH, fluid balance)

• Feedback mechanisms: Negative feedback (most common), positive feedback (less common)

Example: Regulation of blood glucose by insulin and glucagon.

Cell Theory & Structure

Basic Cell Theory

Cells are the basic unit of life, and all living organisms are composed of cells.

• Cell membrane: Surrounds cell, controls entry/exit of substances

• Nucleus: Contains DNA, controls cell activities

• Cytoplasm: Contains organelles (mitochondria, ribosomes, etc.)

Membrane Transport

Cells exchange materials with their environment through various transport mechanisms.

Example: Sodium-potassium (Na+/K+) pump is an active transport mechanism.

Life Span & Cell Growth

Cell Division and Growth

Cells divide and grow through regulated processes, which are essential for development and repair.

• Somatic cells: Undergo mitosis; have 23 pairs of chromosomes

• Cells with high mitochondria: Muscle cells, skeletal, cardiac, liver

• Malignant cells: Cancerous, uncontrolled growth

Abnormal Cell Growth

Abnormal growth can lead to tumors and cancer.

• Tumor: Mass of abnormal cells

• Benign: Non-cancerous, localized

• Malignant: Cancerous, invasive

Osmolarity & pH

Body Fluid Properties

Osmolarity and pH are critical for maintaining cellular function.

• Human body pH: 7.35 - 7.45

• Osmolarity: Water-attracting property; normal osmotic pressure is about 300 mOsmol/L

• Influencing factors: Proteins, glucose, electrolytes

Integumentary System

Skin Structure & Function

The skin is the largest organ, providing protection and regulating body temperature.

• Epidermis: Outer layer, provides barrier

• Dermis: Middle layer, contains nerves, blood vessels

• Hypodermis: Layer under dermis, mostly fat

Accessory Structures

• Hair: Protection, sensation

• Nails: Protect tips of fingers/toes

• Glands: Sebaceous (oil), sweat glands

Vitamin D & Skin

• Vitamin D: Produced in skin upon exposure to sunlight

• Sources: Sunlight, diet

Skeletal System

Bone Structure & Function

Bones provide support, protection, and are the site of blood cell production.

• Red bone marrow: Site of production for red blood cells, white blood cells, platelets

• Epiphyseal line: Growth plate in long bones

Types of Bones

• Long bones: Femur, humerus

• Short bones: Carpals, tarsals

• Flat bones: Skull, ribs

• Irregular bones: Vertebrae

Bone Cells

• Osteoblasts: Create new bone

• Osteoclasts: Break down bone, release calcium

• Osteocytes: Mature bone cells

Bone Growth & Development

• Epiphyseal line: Indicates end of growth in long bones

Summary Table: Bone Cells

Additional info:

• Some content inferred for completeness, such as standard definitions and examples.

• Tables and diagrams referenced in the notes have been recreated in text and HTML table format.