Human Body Structure and Skeletal System

Structural Levels of the Body

• 7 structural levels: Chemical, Organelle, Cell, Tissue, Organ, Organ system, Organism

Skeletal System

• Function: support the body, protect internal organs, assist movement, store minerals and blood cell formation
• Bones: solid network of living cells and proteins surrounded by deposits of calcium salts
• Bone components: articular cartilage, spongy bone, medullary cavity, bone marrow, haversian canal, epiphysis, periosteum
• Osteoblasts form new bones, osteoclasts dissolve bones

Axial and Appendicular Skeleton

• Axial skeleton: supports the central axis of the body
• Appendicular skeleton: supports axis, legs, pelvis, and shoulders

Bone Ossification

• Process of turning cartilage into bones
• Important for the growth of people

Cartilage and Joints

• Cartilage: strong, flexible, connective tissue that protects your joints and bones
• Joints: where two bones meet
• Types of joints: immovable (skull), slightly movable (spine), freely movable (hands)

Muscles

• Three types of muscles: Skeletal, Smooth, Cardiac
• Functions: voluntary movements (controlled by thought), involuntary movements (not controlled by thought)

Muscle Contraction

• Myosin: thick filaments that pull actin to the middle
• Actin: thin filament located on the outer muscle

Tendons and Ligaments

• Tendon: connects muscle to bone
• Ligament: connects bone to bone

Circulatory System

• Function: involves the heart and its functions
• Structures: heart, blood vessels, and blood
• Heart's function: muscular organ that contracts at intervals, freeing blood through the circulatory system
• Blood oxygenation: right side pumps blood from body to lungs, left side pumps blood from lungs to body
• Aorta: pumps blood from heart to body
• Vena Cava: brings blood from body to heart
• Arteries: bring blood from heart to body
• Capillaries: network of very small blood vessels
• Veins: bring blood from body to heart
• Blood function: transports nutrients, gases, enzymes, hormones, waste, regulates temp, pH, electrolytes
• Blood components: red blood cells, white blood cells, plasma

Digestive System

• Function: breaks down food into smaller molecules so that the body can use it
• 4 phases of Digestion:
  • Ingestion: eating
  • Digestion: breaking down food
  • Absorption: absorbing molecules into cells
  • Elimination: removing waste
• Mechanical digestion: physical (chewing)
• Chemical digestion: enzymes breaking down food
• Saliva: helps moisten and dissolve food, contains enzyme amylase
• Esophagus: located from mouth to stomach, moves food down the tube
• Villi: finger-like projections, absorb nutrients
• Pancreas: produces hormones that regulate blood sugar levels
• Liver: produces bile, a fluid with lipids and salts
• Large intestine: absorption of nutrients, prepares waste for elimination