PLTW Human Body Systems – Vocabulary

A comprehensive set of vocabulary flashcards covering Units 1–6 in PLTW Human Body Systems (HBS).

Anatomical Position

Standard body stance: standing upright, facing forward, arms at sides, palms forward

Directional Terms

Words that describe the position of one body part relative to another (e.g., anterior, posterior)

Regional Terms

Names for specific areas of the body (e.g., brachial = arm, cervical = neck)

Tissue

Group of similar cells performing a specific function

Epithelial Tissue

Covers body surfaces and lines organs and cavities

Connective Tissue

Supports, protects, and binds other tissues (e.g., bone, blood, cartilage)

Muscle Tissue

Contracts to produce movement

Nervous Tissue

Transmits electrical impulses for communication

Biometrics

Measurement and analysis of unique physical or behavioral traits for identification

Central Nervous System (CNS)

Brain and spinal cord; processes and integrates information

Peripheral Nervous System (PNS)

All nerves outside the CNS; carries signals to and from the CNS

Neuron

Nerve cell specialized for electrical communication

Dendrite

Branch-like part of a neuron that receives incoming signals

Axon

Long neuron process that carries signals away from the cell body

Synapse

Junction between neurons where neurotransmitters are released

Action Potential

Electrical impulse that travels along a neuron’s membrane

Neurotransmitter

Chemical messenger released at a synapse to transmit a signal

Endocrine System

Collection of glands that secrete hormones into the bloodstream

Hormone

Chemical messenger that travels in blood to affect target cells

Gland

Organ that produces and releases hormones or other substances

ATP (Adenosine Triphosphate)

Primary energy currency of the cell

Enzyme

Protein catalyst that speeds up chemical reactions

Metabolism

Sum of all chemical reactions in the body

Digestive System

Organs that break down food into absorbable nutrients

Mechanical Digestion

Physical breakdown of food (e.g., chewing)

Chemical Digestion

Enzymatic breakdown of food molecules (e.g., amylase action)

Respiratory System

Organs that exchange oxygen and carbon dioxide with the environment

Lungs

Primary respiratory organs where gas exchange occurs

Trachea

Windpipe that conducts air to the bronchi

Bronchi

Two large air passages that branch from the trachea into each lung

Alveoli

Microscopic air sacs in lungs where gas exchange happens

Urinary System

Organs that filter blood, remove waste, and regulate water balance

Kidney

Organ that filters blood to produce urine

Ureter

Tube that carries urine from kidney to bladder

Bladder

Muscular sac that stores urine

Urethra

Tube that carries urine from bladder to outside the body

Skeletal Muscle

Voluntary muscle attached to bones for movement

Tendon

Connective tissue that attaches muscle to bone

Ligament

Connective tissue that connects bone to bone at joints

Joint

Location where two or more bones meet

Flexion

Movement that decreases the angle of a joint

Extension

Movement that increases the angle of a joint

Muscle Contraction

Shortening of muscle fibers to produce force

Sliding Filament Theory

Explanation of how actin and myosin slide to cause muscle contraction

Range of Motion (ROM)

Extent of movement possible at a joint

Integumentary System

Skin, hair, and nails that protect the body

Epidermis

Outer layer of skin

Dermis

Inner skin layer containing nerves, blood vessels, and glands

Skeletal System

Framework of bones that supports, protects, and produces blood cells

Compact Bone

Dense, strong outer layer of bone

Spongy Bone

Porous bone that contains red marrow

Osteoblast

Bone cell that builds new bone tissue

Osteoclast

Bone cell that breaks down bone tissue

Immune System

Body’s defense network against pathogens

Lymphocytes

White blood cells (B-cells and T-cells) involved in specific immunity

Antibody

Protein produced by B-cells that binds to specific antigens

Antigen

Foreign substance that triggers an immune response

Homeostasis

Maintenance of stable internal conditions

Feedback Mechanism

Regulatory loop that helps maintain homeostasis

Negative Feedback

Response that reverses a change to return to set point

Positive Feedback

Response that amplifies a change away from the set point

Endocrine Glands

Hormone-secreting glands such as pancreas and thyroid

Insulin

Hormone that lowers blood glucose levels

Glucagon

Hormone that raises blood glucose levels