Human Body Organization and Cell Structure

Study Notes

The human body is composed of:
- Cells: the basic structural and functional units of life
- Tissues: groups of similar cells that perform specific functions
- Organs: structures composed of two or more types of tissues that work together to perform specific functions
- Organ systems: groups of organs that work together to maintain homeostasis and perform specific functions

Cell membrane: a thin layer of lipid and protein molecules that surrounds the cell and regulates what enters and leaves
Cytoplasm: a gel-like substance inside the cell membrane where metabolic processes occur
Nucleus: the control center of the cell where DNA is stored
Mitochondria: organelles responsible for generating energy for the cell
Ribosomes: organelles responsible for protein synthesis

Epithelial tissue: forms the lining of organs and glands, and regulates what enters and leaves the body
Connective tissue: provides support and structure to the body, and connects organs and tissues
Muscle tissue: responsible for movement and contraction
Nervous tissue: responsible for transmitting and processing information

Nervous system: responsible for controlling and coordinating body functions
Circulatory system: responsible for transporting oxygen and nutrients to cells, and removing waste products
Respiratory system: responsible for exchanging oxygen and carbon dioxide
Digestive system: responsible for breaking down and absorbing nutrients
Endocrine system: responsible for producing and regulating hormones
Immune system: responsible for defending the body against pathogens and disease
Integumentary system: responsible for protecting the body from external damage and regulating body temperature
Muscular system: responsible for movement and maintaining posture
Skeletal system: provides support and structure to the body
Urinary system: responsible for filtering waste and excess substances from the blood

Homeostasis: the ability of the body to maintain a stable internal environment despite changes in external conditions
Negative feedback loops: mechanisms that counteract changes in the body to maintain homeostasis
Interactions between organ systems: the body's systems work together to maintain homeostasis and perform specific functions

Human body is composed of cells, tissues, organs, and organ systems
These components work together to maintain homeostasis and perform specific functions

Epithelial tissue forms the lining of organs and glands, and regulates what enters and leaves the body
Connective tissue provides support and structure to the body, and connects organs and tissues
Muscle tissue is responsible for movement and contraction
Nervous tissue is responsible for transmitting and processing information

Nervous system controls and coordinates body functions
Circulatory system transports oxygen and nutrients to cells, and removes waste products
Respiratory system exchanges oxygen and carbon dioxide
Digestive system breaks down and absorbs nutrients
Endocrine system produces and regulates hormones
Immune system defends the body against pathogens and disease
Integumentary system protects the body from external damage and regulates body temperature
Muscular system is responsible for movement and maintaining posture
Skeletal system provides support and structure to the body
Urinary system filters waste and excess substances from the blood

Homeostasis is the ability of the body to maintain a stable internal environment
Negative feedback loops counteract changes in the body to maintain homeostasis
Organ systems interact to maintain homeostasis and perform specific functions