Comprehensive Study Guide – Human Biology (GOB Chemistry Context)

Levels of Organization in Living Things

Overview

Living organisms are structured in a hierarchical manner, from the simplest chemical units to the most complex forms. Understanding these levels is foundational for studying biology and chemistry in health sciences.

• Atom: Basic unit of matter (e.g., oxygen).

• Molecule: Combination of atoms (e.g., DNA).

• Organelle: Structure within a cell (e.g., mitochondria).

• Cell: Basic unit of life (e.g., squamous epithelial cell).

• Tissue: Group of similar cells performing a function (e.g., epithelial tissue).

• Organ: Group of tissues performing a function (e.g., heart).

• Organ system: Group of organs working together (e.g., cardiovascular system).

• Organism: An entire living being (e.g., human).

Key Differences

• Cell: Single functional unit.

• Tissue: Multiple similar cells.

• Organ: Multiple tissues.

• Organ system: Multiple organs.

• Organism: Complete living being.

Anatomy vs Physiology

Definitions and Examples

• Anatomy: Study of structure. Example: The heart has four chambers.

• Physiology: Study of function. Example: The heart pumps blood throughout the body.

The 11 Organ Systems

System Overview

Organ systems are groups of organs that work together to perform complex functions necessary for life.

System	Main Structures	General Function
Integumentary	Skin, hair, nails, glands	Protection, temperature regulation
Muscular	Skeletal muscles, tendons	Movement, heat production
Nervous	Brain, spinal cord, nerves	Control and coordination
Endocrine	Glands (thyroid, pancreas, etc.)	Hormone regulation
Cardiovascular	Heart, blood vessels	Transport of nutrients, gases, waste
Lymphatic/Immune	Lymph nodes, spleen, thymus	Immunity, fluid balance
Respiratory	Lungs, trachea, bronchi	Gas exchange
Digestive	Mouth, esophagus, stomach, intestines	Break down and absorb nutrients
Urinary	Kidneys, bladder, ureters	Remove waste, water/electrolyte balance
Reproductive	Ovaries, testes, uterus, penis	Produce gametes, reproduction

Tissues

Four Main Types

• Epithelial: Covers surfaces, lines cavities.

• Connective: Supports, protects, binds.

• Muscle: Movement.

• Nervous: Signal transmission.

Components

• Cells: Living part performing function.

• Extracellular matrix (ECM): Nonliving material supporting cells.

Vascularization

• Well vascularized tissues (e.g., muscle) heal faster.

• Poorly vascularized tissues (e.g., cartilage) heal slowly.

Epithelial Tissue

• Characteristics: Tightly packed cells, little ECM, avascular, high regenerative capacity.

• Types by shape: Squamous (flat), Cuboidal (cube), Columnar (tall).

• Types by layers: Simple (one layer), Stratified (multiple layers).

Connective Tissue

• Characteristics: Few cells, abundant ECM, supports/protects.

• Types: Adipose (fat storage), Bone (structural support), Areolar (loose, binds organs), Cartilage (flexible support), Blood (transport), Dense/Fibrous (tendons, ligaments).

Muscle Tissue

• Characteristics: Contractile, allows movement.

• Types: Skeletal (voluntary, striated, multinucleated), Cardiac (involuntary, striated, heart), Smooth (involuntary, non-striated, walls of organs).

Nervous Tissue

• Location: Brain, spinal cord, nerves.

• Function: Transmit electrical impulses.

• Components: Neurons (signal) + neuroglia (support).

Homeostasis

Definition & Mechanisms

• Definition: Maintenance of stable internal environment.

• Control Mechanism:

  • Stimulus: Detects change

  • Receptor: Senses change

  • Control Center: Processes info (brain, endocrine gland)

  • Effector: Produces response

• Feedback Mechanisms:

  • Negative Feedback: Reverses change (e.g., body temp, blood glucose)

  • Positive Feedback: Amplifies change (e.g., childbirth contractions)

Nervous System

Neuron Structure & Function

• Cell body (soma): Contains nucleus, metabolic functions

• Nucleus: Genetic info

• Dendrites: Receive signals

• Axon: Sends signals

• Myelin sheath: Insulation, speeds up impulses

• Schwann cells: Produce myelin

• Nodes of Ranvier: Gaps in myelin, impulse jumps

• Axon terminals: Transmit signal to next cell

Action Potential Steps

1. Resting membrane potential – negative inside

2. Stimulus → depolarization (Na+ enters)

3. Threshold reached → peak

4. Repolarization (K+ exits)

5. Recovery/retesting

• Voltage-gated channels regulate Na+/K+ movement.

• Sodium-Potassium Pump maintains resting potential.

• Propagation: Myelin + nodes increase speed.

Synapses

• Electrical: Direct ion flow

• Chemical: Neurotransmitter release → receptor activation

Neuron Types & Functions

• Sensory (afferent): to CNS

• Motor (efferent): from CNS

• Interneurons: within CNS

Divisions

• CNS: Brain + spinal cord

• PNS: Nerves outside CNS

  • SNS: Voluntary, skeletal muscles

  • ANS: Involuntary, organs

Grey vs White Matter

• Grey: Cell bodies

• White: Myelinated axons

Brain Regions & Functions

• Forebrain: Cerebrum, Thalamus, Hypothalamus

• Brainstem: Midbrain, Pons, Medulla

• Cerebellum: Balance & coordination

• Corpus callosum: Connects hemispheres

• Limbic system: Emotion/memory

• Lateralization: Functional differences between hemispheres

Cardiovascular & Respiratory Systems

Circulatory System

• Components: Heart, blood vessels, blood

• Pulmonary circuit: Heart → lungs → heart (oxygenation)

• Systemic circuit: Heart → body → heart (delivery)

Heart Structure

• Chambers: RA, LA, RV, LV

• Valves: AV (tricuspid/bicuspid), SL (pulmonary/aortic)

• Coronary arteries: Supply heart

• Myocardium: Cardiac muscle layer

• Pericardium: Protective sac

Blood Flow

1. Deoxygenated blood: RA → RV → pulmonary arteries → lungs → pulmonary veins

2. Oxygenated blood: LA → LV → aorta → body

Blood Vessels

• Arteries: High pressure, oxygen-rich

• Veins: Low pressure, valves, muscular/respiratory pump

• Capillaries: Exchange, thin walls

Blood Components

• Plasma + formed elements (RBC, WBC, platelets)

• Hemoglobin: Carries O2

• WBC types: Neutrophils, lymphocytes, monocytes, eosinophils, basophils

Respiratory System

• Structures: Nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

• Alveoli: Gas exchange

• Respiratory membrane: Alveoli + capillaries

• Pulmonary ventilation: Volume & pressure changes (Boyle’s Law)

• Gas exchange: Diffusion (O2 in, CO2 out)

• Feedback loop: High CO2 detected by chemoreceptors → brain → diaphragm/intercostals adjust breathing

• Integration: Works with cardiovascular system to oxygenate tissues and remove CO2

Biological Molecules

Overview

• Organic: Contains carbon

• Hydrocarbon: C + H chains (energy source in food)

• Monomer vs Polymer: Single unit vs chain (e.g., glucose vs starch)

• Reactions:

  • Dehydration synthesis: Builds polymers

  • Hydrolysis: Breaks down polymers

Macromolecules

Molecule	Monomer	Polymer	Function
Carbohydrate	Monosaccharides	Polysaccharides	Energy storage, structure
Lipids	Glycerol + fatty acids	Triglycerides, phospholipids	Energy storage, membranes
Proteins	Amino acids	Polypeptides	Enzymes, structure, transport
Nucleic acids	Nucleotides	DNA/RNA	Genetic info

• Proteins: 4 levels of structure, denaturation = loss of function

• Lipids: Saturated (solid), unsaturated (liquid)

• Carbs: Monosaccharide (glucose), Disaccharide (sucrose), Polysaccharide (starch, glycogen, cellulose)

Digestive System

Overview

• Essential nutrients: Essential amino acids/fatty acids

• Vitamins vs Minerals: Organic vs inorganic

• Organs: Mouth, pharynx, esophagus, stomach, small/large intestines, liver, pancreas, gallbladder

• Processes: Ingestion, mechanical digestion, chemical digestion, secretion, absorption, defecation

• Mechanical vs Chemical digestion: Physical breakdown vs enzyme breakdown

• Peristalsis: Wave-like muscle contractions to move food

• Stomach: Mechanical (churning), Chemical (enzymes, HCl)

• Bile: Produced by liver, stored in gallbladder, emulsifies fats

• Small intestine: Villi, microvilli, circular folds → increase absorption

• Pancreatic secretions: Amylase, lipase, proteases → digest nutrients

• Large intestine: Water absorption, waste compaction

• Sphincters: Control movement of food through the tract

Additional info: This guide is suitable for GOB Chemistry students as it covers foundational biological and chemical principles relevant to health sciences, including molecular structure, organ systems, and physiological processes.