Body Systems (science flashcards)

Vocabulary flashcards covering key terms from Digestive, Circulatory, Respiratory, Excretory, and Nervous systems.

Mechanical digestion

The physical breakdown of food into smaller pieces (e.g., chewing, stomach churning) without chemical changes.

Chemical digestion

Breakdown of large molecules into absorbable units by enzymes and acids

Mouth

Entry point of the digestive system where mechanical digestion and chemical saliva begin digestion.

Teeth

Structures in the mouth that cut, tear, and grind food, increasing surface area for digestion.

Salivary glands

Glands that produce saliva containing enzymes (eg, amylase) to begin carbohydrate digestion.

Oesophagus

Muscular tube that transports swallowed food to the stomach via peristaltic waves.

Stomach

Sac where food is churned with gastric juice (acidic HCl and enzymes) to form chyme.

Liver

Accessory digestive organ producing bile for fat digestion and aiding detoxification of the blood.

Kidneys

Excretory organs that filter blood to remove wastes and regulate water/electrolyte balance.

Small intestine

Main site of chemical digestion and nutrient absorption; lined with villi to increase surface area.

Large intestine

Absorbs water and electrolytes; forms and stores feces.

Rectum

Final section of the large intestine; stores feces before elimination.

Anus

Opening at the end of the digestive tract for excretion of feces.

Villi

Finger-like projections in the small intestine that increase surface area for absorption.

Accessory organs of digestion

Organs that assist digestion beyond the GI tract (eg, liver, pancreas, gallbladder, salivary glands).

Red blood cells (erythrocytes)

Cells that transport oxygen to tissues; contain hemoglobin.

White blood cells (leukocytes)

Immune cells that fight infections.

Platelets

Cell fragments that help blood clotting.

Plasma

Liquid component of blood carrying cells, nutrients, wastes, and hormones.

Left side of the heart

Receives oxygenated blood from the lungs and pumps to the body via the aorta.

Right side of the heart

Receives deoxygenated blood from the body and pumps to the lungs via the pulmonary artery.

Atria

Upper heart chambers that receive blood (left and right).

Ventricles

Lower heart chambers that pump blood out (to body or to the lungs).

Aorta

Main artery; carries oxygenated blood from the left ventricle to the body.

Vena cava

Large veins returning deoxygenated blood to the right atrium.

Pulmonary artery

Carries deoxygenated blood from the right ventricle to the lungs.

Pulmonary vein

Carries oxygenated blood from the lungs to the left atrium.

Valves

Flaps that prevent backflow in the heart (atrioventricular and semilunar valves).

Arteries

Blood vessels that carry blood away from the heart; usually oxygenated.

Veins

Blood vessels that carry blood toward the heart; usually deoxygenated.

Capillaries

Tiny vessels where exchange of oxygen, carbon dioxide, nutrients, and wastes occurs.

Systemic circuit

Pathway delivering blood from the heart to the body and back, supplying oxygen and nutrients.

Gas exchange

Oxygen diffuses from air in the lungs into the blood; carbon dioxide diffuses from blood to air to be exhaled.

Nose/Mouth (respiratory entry)

Entry points for air; filter, warm, and humidify inspired air.

Epiglottis

Flap that prevents food from entering the trachea during swallowing.

Trachea

Windpipe; air passage to the lungs; lined with cilia and mucus.

Bronchi

Two main airways that branch into the lungs.

Bronchioles

Smaller air passages leading to the alveoli.

Alveoli

Air sacs where gas exchange with surrounding capillaries occurs.

Inhalation

Active process where the diaphragm contracts to draw air into the lungs.

Exhalation

Breathing out; diaphragm relaxes and air leaves the lungs.

Alveolar-capillary gas exchange

Oxygen diffuses into blood in the alveoli, carbon dioxide diffuses into alveolar air.

Cellular respiration

Process releasing energy from glucose using oxygen to form ATP, CO2, and water.

Glucose + oxygen (word equation)

Glucose + oxygen -> carbon dioxide + water + energy (ATP).

C6H12O6 + 6 O2 (chemical equation)

C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy (ATP).

Nervous system: Central (CNS)

Brain and spinal cord; processes information and coordinates activity.

Nervous system: Peripheral (PNS)

Nerves outside the CNS that carry signals between the CNS and the body.

Sensory (afferent) neurons

Transmit signals from receptors to the CNS.

Motor (efferent) neurons

Transmit commands from the CNS to muscles and glands.

Interneurons

Connect neurons within the CNS; process and interpret information.

Reflex arc

Simple neural pathway producing a rapid, automatic response to a stimulus.

Dendrites

Structures that receive signals from other neurons or sensors.

Cell body

Control center of the neuron containing the nucleus.

Axon

Long extension that carries nerve impulses away from the cell body.

Axon terminals / nerve endings

Endpoints where signals are transmitted to the next neuron or target cell.

Synapse

Gap between neurons where neurotransmitters are released to pass signals.

Myelin sheath

Insulating layer around many axons that speeds up nerve impulses.

Neurotransmission

Chemical signaling across a synapse via neurotransmitters.

Stimulus-response model

Sequence: stimulus -> receptor -> sensory neuron -> CNS processing -> motor neuron -> effector -> response.