Introduction to Human Physiology Quiz

Introduction to Human Physiology: Cell Components and Organelles

• Human physiology studies the functional activities and mechanisms of the biological body, such as why the heart beats automatically.
• Physiology is derived from the Greek words "physis" (nature) and "logos" (study).

Levels of Organization

• The human body is organized from atoms to organisms.
• Levels are: atom, molecule, macromolecule, organelle, tissue, organ, organ system, and organism.
• Examples include hydrogen, carbon, water, glucose, protein, DNA, nucleus, mitochondrion, bone, muscle, heart, kidney, skeletal system, cardiovascular system, animal, plant, bacterium, and fungus.

Characteristics of Life

• All living organisms share common characteristics essential for life.
• These include reproduction (micro and macro), growth, movement, respiration, responsiveness, digestion, absorption, circulation, assimilation, and excretion.
• Reproduction is essential to maintain the organism's efficiency and growth.
• Movement allows the organism to obtain nutrition, find partners for reproduction, and avoid predators.
• Respiration involves obtaining oxygen and releasing carbon dioxide (or vice-versa for plants).
• Responsiveness allows the organism to react to environmental or other stimuli.
• Digestion is the breakdown of food to produce energy.
• Absorption involves movement of digested food through membranes into body fluids.
• Circulation transports substances through the body.
• Assimilation changes absorbed substances into usable forms for the body's tissues.
• Excretion removes waste substances.

Functions of the Human Cell

• Cellular functions vary depending on the cell type and location in the body.
• Organelles work together to keep cells alive and carry out specific functions.
• Organelles have varied sizes, shapes, and numbers.
• Essential cell functions are intake of nutrients and other substances, processing them, producing new substances, cell replication, and energy production.

Parts of the Human Cell

• The cell contains structural components called organelles, suspended in the cytoplasm, which is contained within the cell membrane.
• Main organelles include the nucleus, cell membrane, endoplasmic reticulum (rough and smooth), Golgi apparatus, lysosomes, peroxisomes, mitochondria, and cytoskeleton.
• The cell has different types of specialized cells, which carry out specific functions to maintain the body's homeostasis.

Cytoskeleton

• The cytoskeleton provides a framework for positioning and moving organelles and macromolecules within the cell.
• Structural components of the cytoskeleton include microtubules (largest), microfilaments (smallest), and intermediate filaments.

Transport in the Cell Membrane

• Endocytosis is the process of transporting particles into a cell by enclosing them in a vesicle.
• Types of endocytosis include phagocytosis ("cell eating") and pinocytosis ("cell drinking").
• Phagocytosis involves engulfing large particles like cells or cellular debris.
• Pinocytosis involves ingesting small amounts of extracellular fluid.
• Exocytosis is the transport of materials from inside the cell to the outside, using membrane-bound vesicles.

Cilia and Flagella

• Cilia are hair-like structures that project from the cell surface, aiding in movement or transporting substances.
• Motile cilia, seen in epithelial cells lining hollow organs and the respiratory system, beat to move fluids or particles.
• Flagella are similar to cilia, but longer and typically fewer in number, facilitating cell movement.

Microvilli

• Microvilli are folds in the cell membrane increasing surface area for rapid diffusion in areas like the intestine and kidney tubules.