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Endocrine System

• Special organs that make hormones, which are chemical messengers that travel in the blood
• Regulates body functions like growth, metabolism, and mood
• Key glands include:
  • Pituitary Gland: Controls other glands
  • Thyroid Gland: Regulates metabolism
  • Adrenal Glands: Manage stress response
  • Pancreas: Regulates blood sugar
  • Ovaries/Testes: Produce sex hormones
• Interacts with the nervous system to maintain balance in the body

Atomic Structure

• Proton: Positive charge
• Neutron: No charge
• Electron: Negative charge
• Atomic Number: Number of protons/electrons
• Atomic Mass: Protons + Neutrons
• Maximum electrons per shell: 2n^2
• Valence electrons determine stability

Elements and Compounds

• Elements are organized in the periodic table by groups (columns) and periods (rows)
• Group 17: Halogens
• Element categories: Alkali Metals, Alkali Earth Metals, Transition Metals, Post-Transition Metals, Metalloids, Non-metals, Noble Gases
• Mixtures: Two or more elements bonded, can be separated
• Compounds: Chemically bonded elements, cannot be separated
• Molecules: Atoms bonded, not visible to the naked eye

Radioactive Decay

• Decay types: Alpha, Beta, Gamma
• Isotopes:
  • Stable Isotopes: Nuclei do not decay, remain unchanged over time, and are abundant in nature
  • Radioactive Isotopes: Nuclei are unstable and decay, emit radiation, and are used in medicine, industry, and research
• Half-life: Time for half the radioactive nuclei to decay, unique to each isotope, and determines decay rate

Nervous System

• Controls everything you do, think, and feel
• Central Nervous System (CNS): Brain and spinal cord
• Function: Neurons send messages, brain stores information and controls actions, senses send messages to the brain, and reactions occur based on messages
• Key parts: Cerebrum, Cerebellum, Brainstem

Neurons

• Special cells that send messages
• Parts of a neuron:
  • Cell Body: Main part, contains the nucleus
  • Dendrites: Branches from the cell body, receive messages from other neurons
  • Axon: Long part, like a wire, sends messages to other neurons or muscles
  • Myelin Sheath: Covers the axon, speeds up message transmission
  • Axon Terminals: End of the axon, release chemicals to send messages to other neurons or muscles
  • Synapse: Gap between neurons, where messages are passed from one neuron to another
  • Neurotransmitters: Chemicals released at the synapse, carry messages between neurons

Body Systems

• Circulatory System: Heart and blood vessels, moves blood and nutrients around the body
• Respiratory System: Lungs and airways, takes in oxygen and removes carbon dioxide
• Digestive System: Mouth, stomach, intestines, breaks down food for energy and removes waste
• Nervous System: Brain, spinal cord, nerves, controls body actions and senses
• Endocrine System: Glands like the thyroid and pituitary, produces hormones for growth and regulates body functions
• Musculoskeletal System: Muscles, bones, joints, supports and moves the body and protects organs
• Immune System: White blood cells, fights off infections and diseases and keeps the body healthy
• Integumentary System: Skin, hair, nails, protects the body from outside harm
• Urinary System: Kidneys, bladder, removes waste from the blood and regulates water balance in the body
• Reproductive System: Male and female, responsible for reproduction