Human Skeletal System

Skeletal System

• Comprises 206 bones that provide support, protection, and movement for the body
• Divided into two main parts:
  • Axial skeleton: skull, vertebral column, ribs, and sternum
  • Appendicular skeleton: upper and lower limbs, pelvis, and shoulder girdle
• Functions:
  • Support: provides framework for the body
  • Protection: protects internal organs
  • Movement: acts as a system of levers and joints to facilitate movement
  • Blood cell production: bones are responsible for producing blood cells
  • Storage: stores minerals such as calcium and phosphorus

Nervous System

• Consists of two main parts:
  • Central nervous system (CNS): brain and spinal cord
  • Peripheral nervous system (PNS): nerves that connect the CNS to the rest of the body
• Functions:
  • Control: regulates and coordinates body functions
  • Communication: transmits and receives information
  • Integration: interprets and responds to sensory information
  • Movement: controls voluntary and involuntary movements
• Types of nerves:
  • Motor nerves: transmit signals from CNS to muscles and glands
  • Sensory nerves: transmit signals from sensory receptors to CNS
  • Mixed nerves: contain both motor and sensory fibers

Respiratory System

• Comprises:
  • Upper respiratory tract: nose, mouth, pharynx, and larynx
  • Lower respiratory tract: trachea, bronchi, bronchioles, and lungs
• Functions:
  • Gas exchange: takes in oxygen and removes carbon dioxide
  • Filtration: filters out dust, bacteria, and other particles
  • Regulation: regulates pH levels by removing excess hydrogen ions
• Mechanisms:
  • Inspiration: diaphragm and intercostal muscles contract to expand chest cavity
  • Expiration: diaphragm and intercostal muscles relax to decrease chest cavity

Lymphatic System

• Comprises:
  • Lymphatic vessels: network of vessels that transport lymph
  • Lymph nodes: filters that remove pathogens and debris from lymph
  • Lymphoid organs: spleen, thymus, and lymphoid tissues
• Functions:
  • Defense: protects against infection and disease
  • Drainage: returns proteins and excess fluids to the bloodstream
  • Fat absorption: absorbs fats and fat-soluble vitamins from the digestive system
• Mechanisms:
  • Lymphatic circulation: lymph flows through vessels and nodes to filter out pathogens
  • Immune response: activates immune cells to fight infection

Immunologic System

• Comprises:
  • Innate immunity: non-specific defense mechanisms
  • Adaptive immunity: specific defense mechanisms that recognize and respond to pathogens
• Functions:
  • Defense: protects against infection and disease
  • Recognition: recognizes and responds to specific pathogens
  • Memory: retains memory of pathogens for future immunity
• Mechanisms:
  • Activation: immune cells are activated to respond to pathogens
  • Response: immune cells respond to pathogens through inflammation, antibody production, and cell-mediated immunity
  • Regulation: immune response is regulated to prevent overreaction and autoimmune disease

Skeletal System

• The skeletal system provides support, protection, and movement for the body through 206 bones
• Axial skeleton consists of skull, vertebral column, ribs, and sternum
• Appendicular skeleton comprises upper and lower limbs, pelvis, and shoulder girdle
• Bones function as a system of levers and joints to facilitate movement
• Bones are responsible for producing blood cells
• Minerals like calcium and phosphorus are stored in bones

Nervous System

• The central nervous system (CNS) consists of the brain and spinal cord
• The peripheral nervous system (PNS) consists of nerves connecting the CNS to the rest of the body
• The nervous system regulates and coordinates body functions
• It transmits and receives information through nerve impulses
• It interprets and responds to sensory information
• Motor nerves transmit signals from CNS to muscles and glands
• Sensory nerves transmit signals from sensory receptors to CNS
• Mixed nerves contain both motor and sensory fibers

Respiratory System

• The upper respiratory tract consists of nose, mouth, pharynx, and larynx
• The lower respiratory tract consists of trachea, bronchi, bronchioles, and lungs
• The respiratory system takes in oxygen and removes carbon dioxide through gas exchange
• It filters out dust, bacteria, and other particles through the filtration mechanism
• It regulates pH levels by removing excess hydrogen ions
• Inspiration occurs when the diaphragm and intercostal muscles contract to expand the chest cavity
• Expiration occurs when the diaphragm and intercostal muscles relax to decrease the chest cavity

Lymphatic System

• The lymphatic system consists of lymphatic vessels, lymph nodes, and lymphoid organs
• Lymphatic vessels transport lymph throughout the body
• Lymph nodes filter out pathogens and debris from lymph
• Lymphoid organs, such as the spleen and thymus, are responsible for immune function
• The lymphatic system protects against infection and disease through defense mechanisms
• It returns proteins and excess fluids to the bloodstream through drainage
• It absorbs fats and fat-soluble vitamins from the digestive system
• Lymphatic circulation involves the flow of lymph through vessels and nodes to filter out pathogens
• The immune response is activated to fight infection

Immunologic System

• The immunologic system consists of innate immunity and adaptive immunity
• Innate immunity provides non-specific defense mechanisms against infection
• Adaptive immunity provides specific defense mechanisms that recognize and respond to pathogens
• The immunologic system protects against infection and disease through defense mechanisms
• It recognizes and responds to specific pathogens through recognition mechanisms
• It retains memory of pathogens for future immunity
• Immune cells are activated to respond to pathogens through activation mechanisms
• The immune response is regulated to prevent overreaction and autoimmune disease