Anatomy & Physiology: Foundations, Cells, Transport, and Body Systems

Introduction to Anatomy & Physiology

Overview

Anatomy and Physiology are foundational sciences that explore the structure and function of the human body. Anatomy focuses on the physical aspects, such as size, shape, and location of body parts, while Physiology studies how these structures perform vital functions.

• Anatomy: Examines the structure of body parts.

• Physiology: Investigates how structures function and interact.

Levels of Organization in the Human Body

Hierarchical Structure

The human body is organized into increasingly complex levels:

• Chemical Level: Atoms combine to form molecules, the building blocks of cells.

• Cellular Level: Cells are the smallest living units, performing specialized functions.

• Tissue Level: Groups of similar cells work together to perform specific functions.

• Organ Level: Organs consist of two or more tissue types working together.

• Organ System Level: Organ systems are groups of organs that coordinate to perform complex functions.

• Organism Level: The organism is a complete living entity.

Cell Structure and Function

Major Organelles and Their Roles

Cells contain specialized structures called organelles, each with distinct functions:

• Golgi Apparatus: Stacked membranes that store, alter, and package secretory products and lysosomal enzymes.

• Endoplasmic Reticulum (ER):

  • Rough ER (RER): Contains ribosomes; synthesizes and modifies proteins.

  • Smooth ER (SER): Lacks ribosomes; synthesizes lipids and carbohydrates.

• Peroxisomes: Spherical vesicles with enzymes that break down fats and neutralize toxins.

• Mitochondria: Tubular organelles producing 95% of the cell's ATP (energy).

• Lysosomes: Vesicles with digestive enzymes for removing damaged organelles or pathogens.

• Nucleus: Central sphere controlling metabolism, storing genetic information, and synthesizing proteins.

• Cytoskeleton: Provides structural support and facilitates movement within the cell.

DNA and RNA: Structure and Function

Key Differences

• DNA (Deoxyribonucleic Acid):

  • Double helix structure.

  • Nitrogenous bases: adenine (A), thymine (T), cytosine (C), guanine (G).

  • Sugar: deoxyribose.

  • Function: Stores genetic information essential for protein synthesis and cellular activities.

• RNA (Ribonucleic Acid):

  • Single strand.

  • Nitrogenous bases: adenine (A), uracil (U), cytosine (C), guanine (G).

  • Sugar: ribose.

  • Function: Involved in protein synthesis.

Cell Cycle

Phases of Cell Division

The cell cycle describes the sequence of events in cell growth and division:

• Interphase: Longest phase; cell prepares for division.

  • G0 Phase: Cells perform normal functions, do not prepare for division.

  • G1 Phase: Cell grows and produces organelles and proteins.

  • S Phase: DNA replication occurs.

  • G2 Phase: Cell continues to grow and prepares for mitosis.

• Mitosis: Nuclear division in somatic cells, includes four stages:

  • Prophase: Chromosomes condense and become visible.

  • Metaphase: Chromosomes align at the cell's equator.

  • Anaphase: Sister chromatids separate and move to opposite poles.

  • Telophase: Nuclear membranes reform around separated chromosomes.

• Cytokinesis: Cytoplasm divides, resulting in two daughter cells.

Types of Membrane Transport

Passive and Active Transport

Cells exchange materials with their environment through various transport mechanisms:

• Passive Transport: Does not require energy.

  • Diffusion: Movement of particles from high to low concentration.

  • Osmosis: Diffusion of water through a semi-permeable membrane.

  • Facilitated Diffusion: Uses carrier proteins to move substances down their concentration gradient.

• Active Transport: Requires energy (ATP).

  • Primary Active Transport: Direct use of ATP (e.g., sodium-potassium pump). $Na^+/K^+$ pump: 3 Na+ out, 2 K+ in per ATP hydrolyzed.

  • Secondary Active Transport: Uses energy indirectly, often involving symport or antiport mechanisms.

• Vesicular Transport: Moves larger particles or droplets.

  • Endocytosis: Includes pinocytosis (cell drinking) and phagocytosis (cell eating).

  • Exocytosis: Expels materials from the cell.

Homeostasis and Regulation

Mechanisms of Regulation

Homeostasis is the body's ability to maintain a stable internal environment despite external changes.

• Autoregulation: Local level adjustment by cells, tissues, or organs.

• Extrinsic Regulation: Involves nervous and endocrine systems.

  • Nervous System: Provides rapid, short-term responses (e.g., increased heart rate during exercise).

  • Endocrine System: Provides longer-term adjustments via hormones.

Anatomic Directional Terms

Common Terms

• Anterior: Front

• Posterior: Back

• Lateral: Side

• Medial: Middle

• Proximal: Near

• Distal: Far

• Superior: Above

• Inferior: Below

• Cranial: Toward the head

• Caudal: Toward the tail

Body Cavities and Regions

Major Cavities

• Dorsal cavity: Includes cranial and spinal cavities.

• Ventral cavity: Includes thoracic and abdominopelvic cavities.

Body Regions

• Examples: Lumbar, cephalic, brachial, umbilical, hypogastric, pubic, inguinal.

Major Body Systems and Their Functions

Overview Table

System	Main Function	Main Organs
Skeletal	Support, protection, mineral storage, blood cell formation	Bones, cartilage, ligaments, bone marrow
Muscular	Movement, protection, support, heat generation	Skeletal muscles, tendons
Nervous	Immediate responses, coordination, sensory information	Brain, spinal cord, nerves
Endocrine	Long-term changes, metabolic activity, development	Glands (pituitary, thyroid)
Cardiovascular	Transport of nutrients, gases, wastes	Heart, blood, blood vessels
Lymphatic	Defense, fluid return	Spleen, lymph nodes
Integumentary	Protection, temperature regulation	Skin, hair, nails
Respiratory	Breathing, gas exchange	Lungs, airways
Digestive	Food processing, absorption	Stomach, intestines, liver
Urinary	Waste removal	Kidneys, bladder

Histology and Pathological Physiology

Definitions

• Histology: The study of tissues and their functions within the body.

• Pathological Physiology: The study of how diseases affect the functions of organs or systems.

Summary

This guide covers the essential concepts of anatomy and physiology, including levels of organization, cell structure, genetic material, cell cycle, membrane transport, homeostasis, anatomical terminology, body systems, and foundational definitions in histology and pathology. Understanding these principles is crucial for further study in health sciences.