Organ Systems and the Circulatory System

These flashcards cover the levels of biological organization from cells to organisms and the specific functions and components of the human circulatory system.

What is the basic unit of life?

Cells are the basic unit of life, and every living thing is made of at least one cell.

How do unicellular organisms maintain their vital functions?

They interact directly with the environment, absorbing nutrients and excreting wastes.

What characterizes multicellular organisms like humans?

They are made of many specialized types of individual cells.

What are specialized cells?

Cells that have certain features or structures that allow them to perform a specific function, such as Neurons or red blood cells.

What is the hierarchy of organization in multicellular organisms?

Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ System $\rightarrow$ Organism.

How is a tissue defined in the transcript?

A group of cells of the same type that work together to perform a specific function.

Why does muscle tissue contain a high number of mitochondria?

Muscle cells contract and relax to generate movement, a process that requires a lot of energy.

What are examples of connective tissue named in the notes?

Tendons and ligaments.

What defines an organ?

A group of different tissues working together to perform a specific function, such as the brain which is made of nerve tissue and blood vessels.

How many organ systems are present in humans?

There are $11$ organ systems in humans.

What constitutes an organism?

A group of organ systems working together to support a living body.

What is the primary function of the heart?

It is a powerful muscular pump that maintains pressure in the circulatory system to move blood around the body.

What are the three main functions of the circulatory system?

1. Transportation of oxygen ($O_2$), carbon dioxide ($CO_2$), nutrients, immune cells, wastes, and heat. 2. Clotting of open wounds. 3. Regulation of body temperature.

What are the structural features and function of arteries?

Arteries are thick, muscular, elastic vessels that carry blood away from the heart.

What are capillaries and why are their walls significant?

Capillaries are tiny blood vessels with walls only one cell thick to allow nutrients and gases to pass into the tissues.

How wide is a capillary in relation to blood cells?

A capillary is only slightly wider in diameter than a single red blood cell.

What are veins and how do they function?

Veins are thin-walled vessels with special valves that carry blood back to the heart and prevent blood from flowing backwards.