Human Organ Function and Systems

Organs: self-contained parts of an organism that maintain homeostasis and perform specific functions
Organ systems: groups of organs that work together to perform a specific function
Examples of organ systems:
- Circulatory system: heart, blood vessels, blood
- Respiratory system: lungs, trachea, diaphragm
- Nervous system: brain, spinal cord, nerves
Organ functions:
- Regulation of body temperature
- Maintenance of pH balance
- Waste removal
- Nutrient absorption
- Production of hormones and enzymes

Cells: basic structural and functional units of the human body
Cell types:
- Epithelial cells: lining of organs and glands
- Connective tissue cells: support and connect tissues
- Muscle cells: contraction and movement
- Nervous cells: transmission of nerve impulses
Cellular components:
- Cell membrane: regulates exchange of substances
- Cytoplasm: site of metabolic reactions
- Nucleus: contains genetic material
- Mitochondria: generate energy for the cell
Cell processes:
- Metabolism: energy production and consumption
- Cell division: growth, development, and repair
- Cell signaling: communication between cells

Epidermis: outermost layer of the skin
- Functions:
  - Barrier against water loss and external factors
  - Production of melanin (skin pigmentation)
- Layers of epidermis:
  - Stratum corneum (outermost)
  - Stratum lucidum
  - Stratum granulosum
  - Stratum spinosum
  - Stratum basale (innermost)
Dermis: middle layer of the skin
- Functions:
  - Support and nourishment of epidermis
  - Regulation of body temperature
- Components:
  - Blood vessels
  - Nerve endings
  - Hair follicles
  - Sweat glands
Hypodermis: innermost layer of the skin
- Functions:
  - Attachment of skin to underlying tissues
  - Storage of fat
- Components:
  - Adipose tissue
  - Areolar connective tissue

Skeletal muscles: voluntary muscles attached to bones
- Functions:
  - Movement and locomotion
  - Maintenance of posture
- Characteristics:
  - Striated appearance
  - Multinucleated
  - Voluntary control
Smooth muscles: involuntary muscles found in internal organs
- Functions:
  - Regulation of internal processes (e.g., digestion)
  - Movement of substances through organs
- Characteristics:
  - Non-striated appearance
  - Single nucleus
  - Involuntary control
Cardiac muscles: involuntary muscles found in the heart
- Functions:
  - Pumping of blood throughout the body
- Characteristics:
  - Striated appearance
  - Branching fibers
  - Involuntary control

Organs are self-contained parts of an organism that maintain homeostasis and perform specific functions
Organ systems are groups of organs that work together to perform a specific function
Examples of organ systems include:
- Circulatory system: heart, blood vessels, blood
- Respiratory system: lungs, trachea, diaphragm
- Nervous system: brain, spinal cord, nerves
Organ functions include:
- Regulation of body temperature
- Maintenance of pH balance
- Waste removal
- Nutrient absorption
- Production of hormones and enzymes

Cells are the basic structural and functional units of the human body
Cell types include:
- Epithelial cells: lining of organs and glands
- Connective tissue cells: support and connect tissues
- Muscle cells: contraction and movement
- Nervous cells: transmission of nerve impulses
Cellular components include:
- Cell membrane: regulates exchange of substances
- Cytoplasm: site of metabolic reactions
- Nucleus: contains genetic material
- Mitochondria: generate energy for the cell
Cell processes include:
- Metabolism: energy production and consumption
- Cell division: growth, development, and repair
- Cell signaling: communication between cells

The epidermis is the outermost layer of the skin
- Functions: barrier against water loss and external factors, production of melanin (skin pigmentation)
- Layers of epidermis include:
  - Stratum corneum (outermost)
  - Stratum lucidum
  - Stratum granulosum
  - Stratum spinosum
  - Stratum basale (innermost)
The dermis is the middle layer of the skin
- Functions: support and nourishment of epidermis, regulation of body temperature
- Components include:
  - Blood vessels
  - Nerve endings
  - Hair follicles
  - Sweat glands
The hypodermis is the innermost layer of the skin
- Functions: attachment of skin to underlying tissues, storage of fat
- Components include:
  - Adipose tissue
  - Areolar connective tissue

Skeletal muscles are voluntary muscles attached to bones
- Functions: movement and locomotion, maintenance of posture
- Characteristics: striated appearance, multinucleated, voluntary control
Smooth muscles are involuntary muscles found in internal organs
- Functions: regulation of internal processes (e.g., digestion), movement of substances through organs
- Characteristics: non-striated appearance, single nucleus, involuntary control
Cardiac muscles are involuntary muscles found in the heart
- Function: pumping of blood throughout the body
- Characteristics: striated appearance, branching fibers, involuntary control