Biology — Body Organization (Tissues, Organs & Systems)

What is the order of body organization from smallest to largest?

cells, then tissues, then organs, then organ systems, then the organism

What is the smallest unit of life?

the cell

Why are viruses debated as living things?

they carry genetic information and can reproduce, but they need a host cell to do it

What is a tissue?

a group of similar cells that work together to carry out a specific function

What are the four types of tissue in the human body?

muscle, nervous, epithelial, and connective

What does muscle tissue do?

it contracts and relaxes to power movement

What are the three types of muscle tissue?

smooth, skeletal, and cardiac

What is smooth muscle?

involuntary muscle in the walls of the digestive tract and blood vessels

What is skeletal muscle?

voluntary muscle attached to bones by tendons

What is cardiac muscle?

heart muscle that pumps blood

What does nervous tissue do?

it senses stimuli and processes and transmits information

What two cell types make up nervous tissue?

neurons and glia

What are neurons?

the basic functional units of the nervous system that carry electrical signals

What are glia?

support cells that hold neurons in place, feed them, and destroy pathogens

What does epithelial tissue do?

it protects the body from pathogens, injury, and water loss

What is epithelial tissue like?

tightly packed sheets of cells that cover surfaces and line body cavities

What does it mean that epithelial cells are polarized?

they have a different top (apical) and bottom (basal) side

What does connective tissue do?

it supports and connects other tissues

What is the extracellular matrix?

a network of proteins and molecules that surrounds and supports cells

Give examples of connective tissue?

bone, cartilage, fat (adipose), and blood

Why is blood a connective tissue?

it is cells suspended in a liquid matrix called plasma

What is an organ?

a structure of two or more tissues working together for a function

Which tissues make up the heart?

cardiac muscle, connective, and nervous tissue

What is an organ system?

a group of related organs that work together

Name some organ systems?

the muscular, skeletal, respiratory, digestive, circulatory, and nervous systems

How do the respiratory and circulatory systems work together?

the circulatory system carries oxygen from the lungs to cells and returns carbon dioxide to be exhaled