Biology: Organisation in Animals

Organisation in Animals

Levels of Organisation

• From simplest to most complex:
  1. Cells
  2. Tissue
  3. Organ
  4. Organ System

Cells

• Basic structural and functional units of life
• Carry out specific functions, e.g. muscle contraction, nerve conduction
• Made up of:
  • Plasma membrane
  • Cytoplasm
  • Genetic material (DNA or RNA)

Tissue

• Group of similar cells that perform a specific function
• Four main types:
  1. Epithelial tissue: forms outer linings, glands, and organs
  2. Connective tissue: provides support, structure, and connectivity
  3. Muscle tissue: enables movement and contraction
  4. Nervous tissue: transmits and processes information
• Tissues work together to form organs

Organ

• Structure composed of two or more types of tissue
• Performs specific functions, e.g. heart pumps blood, liver detoxifies
• Examples:
  • Heart: muscle and connective tissue
  • Liver: epithelial, connective, and blood tissue
  • Brain: nervous and connective tissue

Organ System

• Group of organs that work together to perform a specific function
• Examples:
  • Circulatory system: heart, blood vessels, blood
  • Nervous system: brain, spinal cord, nerves
  • Digestive system: mouth, esophagus, stomach, intestines, etc.
• Organ systems interact to maintain homeostasis and ensure overall functioning of the organism

Organisation in Animals

Levels of Organisation

• Cells are the basic structural and functional units of life
• Tissue is a group of similar cells that perform a specific function
• Organs are structures composed of two or more types of tissue
• Organ systems are groups of organs that work together to perform a specific function

Cells

• Made up of plasma membrane, cytoplasm, and genetic material (DNA or RNA)
• Carry out specific functions, such as muscle contraction and nerve conduction

Tissue

• Four main types: epithelial, connective, muscle, and nervous tissue
• Epithelial tissue forms outer linings, glands, and organs
• Connective tissue provides support, structure, and connectivity
• Muscle tissue enables movement and contraction
• Nervous tissue transmits and processes information
• Tissues work together to form organs

Organ

• Examples: heart, liver, brain
• Heart is composed of muscle and connective tissue
• Liver is composed of epithelial, connective, and blood tissue
• Brain is composed of nervous and connective tissue
• Organs perform specific functions, such as pumping blood or detoxifying

Organ System

• Examples: circulatory system, nervous system, digestive system
• Circulatory system is composed of heart, blood vessels, and blood
• Nervous system is composed of brain, spinal cord, and nerves
• Digestive system is composed of mouth, esophagus, stomach, intestines, etc.
• Organ systems interact to maintain homeostasis and ensure overall functioning of the organism