Anatomy: Cells

• Anatomy is the study of the structure of the body
• Microscopic anatomy is a branch of anatomy that studies the structure of cells, tissues, and organs at the microscopic level

Cells

• Cells are the basic structural and functional units of the body
• They are responsible for carrying out all of the body's functions
• The structure of a cell is related to its function
• Cells are composed of a variety of organelles that perform specific functions
• The main parts of a cell include the plasma membrane, cytoplasm, and nucleus
• The plasma membrane is the outer boundary of the cell, and it controls the movement of substances into and out of the cell
• It is composed of a phospholipid bilayer with embedded proteins
• The proteins in the plasma membrane can act as channels, carriers, or receptors
• The cytoplasm is the gel-like substance inside the cell, and it contains the organelles
• The organelles are responsible for carrying out specific functions, such as protein synthesis, energy production, and waste disposal
• The nucleus is the control center of the cell, and it contains the DNA
• The DNA contains the instructions for making proteins
• There are many different types of cells in the body, each with its own unique structure and function
• Some examples of cells include:
• Epithelial cells: cover the surfaces of the body, and they protect the body from the environment
• They also secrete and absorb substances
• Muscle cells: responsible for movement
• They can contract and relax
• Nerve cells: transmit signals throughout the body
• They can receive and transmit electrical and chemical signals
• Connective tissue cells: connect and support other tissues
• They include fibroblasts, chondrocytes, and osteocytes

Tissues

• Tissues are groups of similar cells that perform a specific function
• There are four main types of tissues in the body:
• Epithelial tissue: covers the surfaces of the body, and it protects the body from the environment
• It also secretes and absorbs substances
• There are many different types of epithelial tissue, each with its own unique structure and function
• Some examples of epithelial tissue include:
• Squamous epithelium: is a thin, flat tissue that allows for easy diffusion of substances
• Cuboidal epithelium: is a cube-shaped tissue that secretes and absorbs substances
• Columnar epithelium: is a column-shaped tissue that secretes and absorbs substances
• Transitional epithelium: is a tissue that can change shape, and it is found in the urinary bladder
• Pseudostratified columnar epithelium: is a tissue that appears to be stratified, but it is actually only one layer of cells
• Connective tissue: connects and supports other tissues
• It is the most abundant type of tissue in the body
• There are many different types of connective tissue, each with its own unique structure and function
• Connective tissue proper: includes loose connective tissue and dense connective tissue
• Cartilage: is a strong, flexible tissue that provides support and cushioning
• Bone: is a hard, rigid tissue that provides support and protection
• Blood: is a fluid tissue that transports oxygen, nutrients, and waste products
• Muscle tissue: responsible for movement
• There are three types of muscle tissue:
• Skeletal muscle: is attached to bones, and it is responsible for voluntary movement
• Smooth muscle: is found in the walls of internal organs, and it is responsible for involuntary movement
• Cardiac muscle: is found in the heart, and it is responsible for pumping blood
• Nervous tissue: transmits signals throughout the body
• It is found in the brain, spinal cord, and nerves
• There are two main types of nervous tissue:
• Neurons: are nerve cells that transmit electrical signals
• Glial cells: are support cells that help neurons function

Organs

• Organs are structures that are composed of two or more different types of tissues
• They perform a specific function in the body
• Some examples of organs include:
• The heart: pumps blood throughout the body
• The lungs: exchange oxygen and carbon dioxide
• The stomach: digests food
• The intestines: absorb nutrients
• The kidneys: filter waste products from the blood
• The liver: produces bile and detoxifies the blood
• The brain: controls the body's functions

Organ Systems

• Organ systems are groups of organs that work together to perform a specific function
• There are 11 organ systems in the body:
• Integumentary system: protects the body from the environment
• It includes the skin, hair, and nails
• Skeletal system: provides support and protection
• It includes the bones, cartilage, and ligaments
• Muscular system: allows for movement
• It includes the skeletal muscles, smooth muscles, and cardiac muscle
• Nervous system: transmits signals throughout the body
• It includes the brain, spinal cord, and nerves
• Endocrine system: produces hormones that regulate the body's functions
• It includes the glands that secrete hormones
• Cardiovascular system: transports blood throughout the body
• It includes the heart, blood vessels, and blood
• Lymphatic system: protects the body from infection
• It includes the lymph nodes, lymphatic vessels, and lymphoid organs
• Respiratory system: exchanges oxygen and carbon dioxide
• It includes the lungs, trachea, and bronchi
• Digestive system: digests food and absorbs nutrients
• It includes the mouth, esophagus, stomach, intestines, liver, pancreas, and gallbladder
• Urinary system: filters waste products from the blood
• It includes the kidneys, ureters, urinary bladder, and urethra
• Reproductive system: produces offspring
• It includes the gonads, reproductive organs, and accessory glands