1. What is Anatomy and Physiology?

• Anatomy: The study of the structure of the body, including the shapes, sizes, and relationships of different parts (organs, tissues, and cells).

• Physiology: The study of the function of the body’s parts and how they work together to sustain life.

Both fields are closely linked: Anatomy focuses on "what" and "where," while Physiology explores "how" these parts function.

2. Levels of Organization in the Human Body

The human body is organized into different levels of structural complexity:

1. Chemical Level: Atoms combine to form molecules, which are the building blocks of all matter.

   • Example: Water (H₂O), proteins, carbohydrates.

2. Cellular Level: Cells are the basic units of life. Different types of cells have specific structures and functions.

   • Example: Muscle cells, nerve cells, blood cells.

3. Tissue Level: Tissues are groups of similar cells that work together to perform a common function.

   • Types of tissues:

     • Epithelial Tissue: Covers body surfaces and lines body cavities.

     • Connective Tissue: Supports and binds other tissues (e.g., bone, blood, cartilage).

     • Muscle Tissue: Responsible for movement (e.g., skeletal, cardiac, smooth).

     • Nervous Tissue: Conducts electrical impulses for communication (e.g., brain, spinal cord).

4. Organ Level: Organs are made up of different tissues working together to perform specific functions.

   • Example: Heart, liver, lungs, kidneys.

5. Organ System Level: Groups of organs work together to perform complex functions.

   • Example: Cardiovascular system, digestive system, nervous system.

6. Organism Level: The entire human body, made up of all the organ systems working together to maintain life.

3. Major Organ Systems of the Body

a) Integumentary System

• Organs: Skin, hair, nails, glands.

• Functions: Protects the body, regulates temperature, provides sensory information.

b) Skeletal System

• Organs: Bones, joints, cartilage.

• Functions: Provides structure, supports and protects internal organs, produces blood cells, stores minerals.

c) Muscular System

• Organs: Skeletal muscles, tendons.

• Functions: Facilitates movement, maintains posture, generates heat.

d) Nervous System

• Organs: Brain, spinal cord, nerves.

• Functions: Controls body functions, processes information, allows communication between body parts.

e) Endocrine System

• Organs: Glands (e.g., thyroid, adrenal, pancreas).

• Functions: Produces hormones that regulate metabolism, growth, reproduction, and other functions.

f) Cardiovascular System

• Organs: Heart, blood vessels (arteries, veins, capillaries).

• Functions: Transports blood, nutrients, oxygen, and waste products throughout the body.

g) Respiratory System

• Organs: Lungs, trachea, bronchi, diaphragm.

• Functions: Facilitates gas exchange (oxygen in, carbon dioxide out), helps regulate pH balance.

h) Digestive System

• Organs: Mouth, esophagus, stomach, intestines, liver, pancreas.

• Functions: Breaks down food, absorbs nutrients, eliminates waste.

i) Urinary System

• Organs: Kidneys, bladder, urethra.

• Functions: Eliminates waste, regulates water balance and electrolytes.

j) Reproductive System

• Organs: Ovaries, testes, uterus, prostate.

• Functions: Produces sex cells and hormones, allows for reproduction and development of offspring.

k) Lymphatic/Immune System

• Organs: Lymph nodes, spleen, thymus, lymphatic vessels.

• Functions: Defends the body against infections, removes excess fluid, absorbs fats from the digestive system.

4. Homeostasis

• Definition: Homeostasis is the process by which the body maintains a stable internal environment despite external changes (e.g., temperature, pH, blood pressure).

• Feedback Mechanisms:

  • Negative Feedback: Most common. It reduces or opposes the initial stimulus to bring the body back to a normal state.

    • Example: Regulation of body temperature (sweating to cool down).

  • Positive Feedback: Enhances or amplifies the initial stimulus.

    • Example: Blood clotting, childbirth contractions.

5. Cell Structure and Function

a) Cell Membrane

• Structure: Phospholipid bilayer with embedded proteins.

• Function: Controls the movement of substances in and out of the cell, provides protection.

b) Nucleus

• Structure: Membrane-bound, contains DNA.

• Function: Acts as the control center of the cell, stores genetic information.

c) Mitochondria

• Structure: Double-membrane organelle.

• Function: Produces energy (ATP) through cellular respiration.

d) Endoplasmic Reticulum (ER)

• Structure: Network of membranes.

• Function:

  • Rough ER: Has ribosomes, synthesizes proteins.

  • Smooth ER: No ribosomes, synthesizes lipids, detoxifies substances.

e) Ribosomes

• Structure: Small particles of RNA and proteins.

• Function: Protein synthesis.

f) Golgi Apparatus

• Structure: Stacked, membrane-bound sacs.

• Function: Modifies, sorts, and packages proteins and lipids for transport.

g) Lysosomes

• Structure: Membrane-bound sacs of digestive enzymes.

• Function: Breaks down waste materials and cellular debris.

6. Basic Physiology Concepts

a) Metabolism

• The sum of all chemical reactions in the body. It includes:

  • Anabolism: Building larger molecules from smaller ones (e.g., protein synthesis).

  • Catabolism: Breaking down larger molecules into smaller ones (e.g., digestion, energy production).

b) Cellular Respiration

• The process by which cells produce energy (ATP) by breaking down glucose in the presence of oxygen.

  • Aerobic Respiration: Requires oxygen, occurs in mitochondria.

  • Anaerobic Respiration: Does not require oxygen, produces less energy (e.g., during intense exercise).

c) Fluid and Electrolyte Balance

• Essential for maintaining normal cell function. Key electrolytes include sodium (Na+), potassium (K+), and calcium (Ca2+), which are vital for nerve impulses, muscle contraction, and water balance.

d) Nervous System Functions

• The nervous system controls voluntary and involuntary actions through:

  • Central Nervous System (CNS): Brain and spinal cord.

  • Peripheral Nervous System (PNS): Nerves that extend from the CNS to the rest of the body.

  • Autonomic Nervous System: Controls involuntary functions (e.g., heart rate, digestion).

7. Common Terms in Anatomy and Physiology

• Anterior (Ventral): Toward the front of the body.

• Posterior (Dorsal): Toward the back of the body.

• Superior: Toward the head (above).

• Inferior: Toward the feet (below).

• Medial: Toward the midline of the body.

• Lateral: Away from the midline.

• Proximal: Closer to the point of attachment or origin.

• Distal: Farther from the point of attachment or origin.