Science

• Hair


  • Made up of a protein called keratin
  • Grows from hair follicles located in the skin
  • Color determined by pigments called melanin
• Skin


  • Largest organ of the body
  • Protects the body from external elements and regulates body temperature
  • Has three layers: epidermis, dermis, and subcutaneous tissue
• Epidermis


  Outermost layer of the skin
• Dermis


  Middle layer of the skin, located beneath the epidermis
• Subcutaneous Tissue (Hypodermis)


  Innermost layer of the skin
• Skeletal System


  • Provides support, protection, and movement for the body
  • Made up of bones, joints, and connective tissues
• Bones


  • Provide support and structure to the body, giving it shape and form
  • Store minerals such as calcium and phosphorus, which are essential for various bodily functions
• Joints


  • Points where two or more bones meet
  • Different types of joints enable different types of movement, such as hinge joints (e.g., elbows and knees) for bending and straightening, ball-and-socket joints (e.g., shoulders and hips) for a wide range of motion, and pivot joints (e.g., neck) for rotational movement
• Cartilage


  Flexible connective tissue found at the ends of bones and in certain joints
• Ligaments


  Tough bands of connective tissue that connect bones to other bones in a joint
• Muscular System


  • Allows for movement and provides support to the body
  • Has three types of muscles: skeletal, smooth, and cardiac
• Skeletal Muscles


  • Attached to the bones of the skeleton
  • Responsible for voluntary movements, such as walking, running, and lifting objects
• Smooth Muscles


  • Found in the walls of internal organs, blood vessels, and other structures
  • Involuntary muscles, meaning they are not under conscious control
• Cardiac Muscles


  • Found only in the heart
  • Involuntary muscles that contract rhythmically to pump blood throughout the body
• Circulatory System


  Consists of the heart, blood vessels, and blood
• Heart


  • Acts as a pump, continuously contracting and relaxing to circulate blood throughout the body
  • Has four chambers: two atria (left and right) and two ventricles (left and right)
  • The atria receive blood returning to the heart, while the ventricles pump blood out of the heart to the rest of the body
• Blood Vessels


  • A network of tubes that carry blood throughout the body
  • Arteries carry oxygenated blood away from the heart to various parts of the body
  • Veins carry deoxygenated blood back to the heart
  • Capillaries connect arteries and veins, allowing for the exchange of oxygen, nutrients, and waste products between the blood and body tissues
• Blood


  • Carries oxygen, nutrients, hormones, and immune cells to different parts of the body
  • Consists of red blood cells, white blood cells, platelets, and plasma
• Respiratory System


  • Responsible for the exchange of oxygen and carbon dioxide
  • Includes the nose, trachea, bronchi, and lungs
• Nose


  Primary entrance for air into the respiratory system
• Trachea


  • Connects the nose and mouth to the lungs
  • Lined with cilia and mucus-producing cells that help filter and trap foreign particles to prevent them from entering the lungs
• Bronchi


  • The trachea branches into two bronchi, one leading to each lung
  • The bronchi further divide into smaller bronchioles, which eventually lead to tiny air sacs called alveoli
• Lungs


  • Main organs of the respiratory system
  • Responsible for the exchange of oxygen and carbon dioxide during breathing
• Digestive System


  Processes food and absorbs nutrients
• Mouth


  • Receives food and begins the process of mechanical digestion through chewing and mixing with saliva
  • Saliva, produced by the salivary glands, contains enzymes that start the chemical breakdown of carbohydrates
• Esophagus


  Muscular tube that connects the mouth to the stomach
• Stomach


  • Muscular organ that receives food from the esophagus
  • Produces gastric juices, including hydrochloric acid and enzymes, to break down proteins
• Small Intestine


  • Longest part of the digestive system
  • Responsible for the digestion and absorption of nutrients, including carbohydrates, proteins, and fats
• Large Intestine (Colon)


  Receives undigested food from the small intestine
• Liver


  • Largest internal organ in the body
  • Produces bile, which helps in the digestion and absorption of fats
  • Metabolizes nutrients, detoxifies harmful substances, and stores vitamins and minerals
• Pancreas


  • Gland located behind the stomach
  • Produces insulin and glucagon, hormones that regulate blood sugar levels
• Nervous System


  • Controls and coordinates the body's functions
  • Divided into two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS)
• Central Nervous System (CNS)


  • Includes the brain and spinal cord
  • Brain receives and processes sensory information, initiates and coordinates responses, and controls bodily functions
  • Spinal cord relays signals between the brain and the rest of the body and controls reflex actions
• Peripheral Nervous System (PNS)


  • Includes nerves and ganglia
  • Nerves transmit signals between the CNS and the rest of the body
  • Ganglia are clusters of nerve cell bodies located outside the CNS and are involved in the processing and integration of sensory information
• Neurons


  • Specialized cells that transmit electrical signals called nerve impulses
  • Cell body contains the nucleus and other cellular components
  • Dendrites receive signals from other neurons and transmit them to the cell body
  • Axon carries nerve impulses away from the cell body and transmits them to other neurons or target cells
  • Synapses are the junctions between neurons where nerve impulses are transmitted from one neuron to another or to a target cell
• Sensory Organs


  Detect various stimuli from the environment, such as the eyes, ears, nose, tongue, and skin
• Urinary System


  • Filters waste products from the blood and excretes them as urine
  • Includes the kidneys, ureters, urinary bladder, and urethra
• Kidneys


  • Bean-shaped organs that filter waste products, excess water, and other substances from the blood to form urine
  • Regulate the levels of electrolytes, such as sodium, potassium, and calcium, in the body
• Ureters


  • Long, muscular tubes that connect each kidney to the urinary bladder
  • Transport urine from the kidneys to the bladder through peristaltic contractions
• Urinary Bladder


  • Hollow, muscular organ that stores urine
  • Expands as urine accumulates and contracts when it is time to empty the bladder