Topic 1: Introduction to Human Physiology

Overview of Human Physiology

Human physiology is the scientific study of the functions and mechanisms occurring in the human body. It explores how organ systems, tissues, and cells work together to maintain life and homeostasis.

• Characteristics of Living Organisms: Includes organization, metabolism, responsiveness, growth, reproduction, and homeostasis.

• Levels of Structural Organization: Six levels: chemical, cellular, tissue, organ, organ system, and organism.

• Body Systems: Eleven major organ systems (e.g., circulatory, respiratory, nervous, etc.).

• Types of Physiology: Systemic, cellular, and pathological physiology.

• Anatomical Position & Directional Terms: Standard reference position; terms include superior/inferior, anterior/posterior, medial/lateral, etc.

• Regional Terms: Specific areas of the body (e.g., brachial for arm, femoral for thigh).

• Body Cavities: Posterior (dorsal) cavity and anterior (ventral) cavity house major organs.

• Core Principles in Anatomy and Physiology: Four main principles: homeostasis, cell theory, energy flow, and structure-function relationship.

• Physiological Processes: Mechanisms that maintain homeostasis, such as feedback loops.

• Homeostasis: The body's ability to maintain stable internal conditions. Common misconceptions: Homeostasis is not a static state but a dynamic equilibrium.

• Feedback Loops: Negative feedback (reduces change) and positive feedback (amplifies change). Example: Regulation of blood glucose by insulin (negative feedback).

• Structure and Function: Complementarity at all levels; structure determines function.

• Cell-Cell Communication: Essential for coordinating body functions via chemical and electrical signals.

Additional info:

• Homeostasis is maintained by physiological processes such as temperature regulation, pH balance, and fluid balance.

Topic 2A & 2B: Cell Physiology

Chemical Reactions & Enzymes

Cell physiology focuses on the chemical and physical processes that occur within cells, including metabolism and enzyme activity.

• Chemical Reactions: Processes where substances are transformed into new products; essential for metabolism.

• Enzymes: Biological catalysts that speed up chemical reactions without being consumed.

• Levels of Chemical Reactions: Catabolic (breakdown) and anabolic (synthesis) reactions.

• Reaction Rates: Influenced by temperature, pH, substrate concentration, and enzyme activity.

• Proteins & Nucleic Acids: Structure and function; proteins act as enzymes, nucleic acids store genetic information.

Example:

• Enzyme amylase catalyzes the breakdown of starch into sugars.

Topic 2C & 2D: The Cell

Cell Structure and Function

Cells are the basic units of life, with specialized structures that perform distinct functions necessary for survival.

• Basic Processes of Cells: Include metabolism, growth, response to stimuli, and reproduction.

• Overview of Cell Structure: Plasma membrane, cytoplasm, and nucleus.

• Plasma Membrane: Fluid mosaic model; composed of phospholipids, proteins, and cholesterol.

• Functions of Membrane Proteins & Lipids: Transport, signaling, structural support.

• Transport Across Plasma Membrane:

  • Passive Transport: Diffusion, osmosis, facilitated diffusion (no energy required).

  • Active Transport: Requires energy (ATP); includes pumps and vesicular transport.

• Types of Transport: Primary (direct use of ATP) and secondary (indirect use of ATP).

Example:

• Na+/K+ pump maintains cellular ion gradients (active transport).

Topic 3: Muscle Physiology & Control of Body Movements

Muscle Structure and Function

Muscle physiology examines how muscles contract, generate force, and enable movement. It also explores the neural control of voluntary and involuntary movements.

• Functions & Types of Muscle Tissue: Skeletal, cardiac, and smooth muscle; each with unique structure and function.

• Structure of Myofibril & Sliding-Filament Mechanism: Myofibrils contain actin and myosin filaments; contraction occurs as filaments slide past each other.

• Membrane Potential in Muscle Cells: Resting and action potentials; essential for muscle contraction.

• Action Potentials: Electrical signals that trigger muscle contraction.

• Neuromuscular Junction: Synapse between motor neuron and muscle fiber; site of signal transmission.

• Phases of Skeletal Muscle Contraction: Excitation, excitation-contraction coupling, contraction, and relaxation.

• Sliding-Filament Mechanism: Crossbridge cycling between actin and myosin.

• Muscle Relaxation & Rigor Mortis: Relaxation occurs when Ca2+ is removed; rigor mortis is post-mortem muscle stiffness.

• Energy Sources for Skeletal Muscle: ATP, creatine phosphate, glycolysis, and oxidative phosphorylation.

• Muscle Tension: Depends on fiber length, frequency of stimulation, and motor unit recruitment.

• Summation & Tetanus: Increased frequency of stimulation leads to greater tension (summation) and sustained contraction (tetanus).

• Length-Tension Relationship: Optimal sarcomere length produces maximal tension.

• Classes of Skeletal Muscle Fibers: Slow-twitch (Type I) and fast-twitch (Type II); differ in contraction speed and fatigue resistance.

• Motor Units: A motor neuron and all the muscle fibers it innervates; controls muscle tone and force.

• Types of Muscle Contractions: Isotonic (change in length) and isometric (no change in length).

• Changes Caused by Physical Training: Hypertrophy (increase in size), endurance, resistance, and atrophy (decrease in size).

• Muscle Fatigue & EPOC: Fatigue is reduced ability to generate force; EPOC (Excess Post-exercise Oxygen Consumption) is increased oxygen intake after exercise.

Control of Body Movements

Body movements are coordinated by the nervous system, involving both central and peripheral components.

• Role of the Spinal Cord: Contains motor tracts (corticospinal and corticobulbar) for voluntary movement.

• Role of the Brain: Initiates and plans voluntary movement; includes motor cortex and basal ganglia.

• Motor Programs: Neural circuits that produce coordinated movement patterns.

• Role of the Peripheral Nervous System (PNS): Transmits motor output to muscles via lower motor neurons.

• Big Picture of Movement Control: Integration of sensory input, motor planning, and execution by the nervous system.

Additional info:

• Motor learning involves changes in neural pathways to improve movement efficiency.

Summary Table: Types of Muscle Fibers

Key Equations

• ATP Hydrolysis:

• Resting Membrane Potential (Nernst Equation):

• Muscle Force Summation: