General Biology: Unit-wise Revision Notes

Introduction to Life and Human Biology

Key Concepts & Keywords

• Biology: The science that studies life and living organisms, explaining how organisms grow, function, interact, and evolve.

• Scope of Biology: Includes study of animals, plants, cells, organs, diseases, body functions, and biotechnology.

• Human Biology: Focuses on human body structure, health, diseases, and interactions with the environment.

Characteristics of Life

• Common features: Growth, reproduction, metabolism, response to stimuli, movement, cellular organization, and adaptation.

Organization of the Body

• Anatomy: Structure of body parts and organs.

• Physiology: How the body functions.

• Metabolism: Chemical and physical reactions in the body.

Health & Disease

• Health: Normal functioning of body and mind.

• Disease: Disturbance to normal structure or function.

Body Organization & Terminology

Anatomical Position & Directional Terms

• Anatomical Position: Body standing upright, facing forward, arms at sides, palms facing front.

• Superior / Inferior: Above / below

• Anterior / Posterior: Front / back

• Medial / Lateral: Toward midline / away from midline

• Proximal / Distal: Near to / far from origin

• Superficial / Deep: Closer to / further from surface

Body Planes

• Sagittal: Divides body into left/right

• Frontal (Coronal): Front/back

• Transverse (Cross): Upper/lower

Body Cavities

• Dorsal cavity: Cranial & spinal cords

• Ventral cavity: Thoracic and abdominopelvic

Abdominal Quadrants

• RUQ, LUQ, RLQ, LLQ: Used to help locate pain or organs

Cell Structure & Function

Key Concepts & Keywords

• Cell: Smallest structural and functional unit of life.

• Cell Membrane: Made of lipid bilayer and proteins; selectively allows substances in/out.

Transport Mechanisms

• Passive: No ATP needed (e.g., diffusion, osmosis)

• Active: Uses ATP energy (e.g., active transport)

• Diffusion: High to low concentration

• Osmosis: Water movement across membrane

• Endocytosis/Exocytosis: Bulk material entry/exit

Osmotic Terms

• Isotonic: Equal solute

• Hypotonic: Lower solute (cell swells)

• Hypertonic: Higher solute (cell shrinks)

Cell Organelles & Functions

• Nucleus: Contains DNA (chromosomes)

• Mitochondria: Produces energy ("powerhouse")

• Ribosomes: Protein synthesis

• Endoplasmic Reticulum (ER): Rough (protein making), Smooth (lipid making)

• Golgi Apparatus: Packages and transports proteins

• Lysosomes: Cell digestion and waste removal

• Cytoplasm: Cell organelles are suspended here

• Plasma Membrane: Regulates entry/exit

Tissues & Histology

Four Basic Tissue Types

• Epithelial: Covers surfaces, lines organs, forms glands

• Connective: Supports, binds, stores energy (e.g., bone, blood, fat)

• Nervous: Rapid signal transmission

• Muscle: Movement

Histology

• Study of tissues under microscope

Supportive & Connective Tissues

Bone & Cartilage

• Bone: Support, protection, mineral storage, movement, blood formation

• Cartilage: Flexible support

• Types of Bone Cells: Osteoblasts (build), Osteoclasts (break down), Osteocytes (maintain)

Muscle System

Muscle Types

• Skeletal: Voluntary, attached to bones

• Cardiac: Involuntary, only in heart

• Smooth: Involuntary, found in organs and blood vessels

Major Muscle Actions

• Biceps brachii: Flexes elbow

• Triceps brachii: Extends elbow

• Quadriceps: Extends the knee

• Hamstrings: Flex the knee

Circulatory System

Heart Structure & Function

• Heart: Muscular pump that maintains circulation and pressure

• Chambers: 4 (2 atria, 2 ventricles)

• Valves: Prevent backflow

• Blood Vessels: Arteries (carry blood away), veins (carry blood to heart), capillaries (exchange)

Blood Circulation

• Systemic: Heart to body

• Pulmonary: Heart to lungs

Respiratory System

Lung Volumes & Definitions

Term	Full Form	Memory Hint
TV	Tidal Volume	Normal breath in/out
VC	Vital Capacity	Max air exhaled after max inhale (sum of TV, IRV, ERV)
RV	Residual Volume	Air left after max exhale
IRV	Inspiratory Reserve Volume	Extra air inhaled after normal inhale
ERV	Expiratory Reserve Volume	Extra air exhaled after normal exhale

Homeostasis & Feedback

Key Concepts

• Homeostasis: Maintaining internal environment for survival

• Regulated Variables: Temperature, pH, glucose, etc.

• Feedback Mechanisms: Negative (stabilizes), Positive (amplifies)

Blood Groups

ABO Blood Group System

Type	Antigen	Receiving Hint
A	A	Receives A, O
B	B	Receives B, O
AB	A & B	Universal recipient
O	None	Universal donor

Definitions Quick Table

Term	Definition Keywords + Hint
Diffusion	Movement from high to low concentration
Osmosis	Water movement across membrane
Homeostasis	Maintaining internal stability
Histology	Study of tissues