Biology Chapter on Observation and Systems

Observation and Inference

• Observation: Using the senses or a measuring device to gather information. Example: A footprint in the sand had four claw marks.
• Inference: A conclusion based on an observation. Example: An animal had been on the sand.

Pellagra

• Pellagra was a disease caused by a lack of niacin (vitamin B) in the diet.

Levels of Organization

• Cells form tissues.
• Tissues form organs.
• Organs form organ systems.
• Organ systems form an organism.

Digestive System

• Function: Absorb nutrients needed by all body cells.
• Mechanical breakdown (teeth, tongue): Increases speed of chemical breakdown.
• Teeth: Primarily responsible for mechanical breakdown.
• Chemical digestion: Mainly occurs with acids in the stomach and intestines.
• Both mechanical and chemical breakdown are needed for nutrient absorption.
• Large intestine: An organ in the digestive system.
• Average small intestine length: 15-18 feet.
• Path: Mouth > esophagus > stomach > small intestine > large intestine > rectum.

Nervous System

• Function: Senses the external world, controls the body, and allows communication between body systems.
• Parts: Brain (3 lbs), spinal cord, nerves (sensory and motor).
• Sensory nerves: More concentrated in fingers than palm/forearm.

Respiratory System

• Function: Takes in oxygen and releases carbon dioxide (waste).
• Inhalation: Lungs expand (inflate).
• Exhalation: Lungs shrink (deflate).
• Diaphragm: Muscle that contracts during inhalation and relaxes during exhalation.
• Main Structures: Nose, mouth, trachea, lungs, bronchi, bronchioles, alveoli.

Circulatory System

• Function: Transports oxygen, nutrients, and waste throughout the body.
• Nutrients: Transported by blood, needed by all cells and absorbed in the small intestine.
• Capillaries: Deliver oxygen and nutrients to cells.
• Oxygen transfer: From blood to organs through capillary walls.
• Heart: Pumps blood throughout the body.
• Arteries: Carry blood away from the heart.
• Veins: Carry blood toward the heart.
• Valves: Prevent blood from flowing backward.
• Pulse: Heartbeats per unit of time.
• Normal resting pulse: 60-80 beats per minute.
• Exercise effect on pulse: Increases after exercise; decreases after regular exercise.

Skeletal and Muscular Systems

• Bones at birth vs. adulthood: More at birth, some fuse.
• Adult bones: 206.
• Bone growth: Continues until about age 20.
• Bone distribution: More than half in hands and feet.
• Tendons: Attach muscles to bones.
• Ligaments: Connect bones for stability.
• Skull: Cranium; protects the brain.
• Ribs: Protect the heart and lungs.
• Vertebrae: Protect the spinal cord (a bundle of nerves).
• Smallest bones: Hammer, anvil, stirrup (in ears).
• Longest/strongest bone: Femur (thighbone).
• Hardest substance: Enamel (teeth).
• Cartilage: Flexible, sturdy tissue (ears, nose).
• Red blood cell production: Marrow in long bones.