Introduction to Cells, Tissues,

Organs and Systems

304-7 Explain structural and functional relationships

between and among cells, tissues, organs and

systems in the human body

110-2 Compare the early idea that living organisms

were made of air, fire and water with the modern cell

theory

In previous grades when you have studied living things, you have not broken them down into their smallest units, cells. However, this year, you get to learn about the cell in great detail.

We will explore how the cell is important to life and we will explore the human body to see how cells make tissues, tissues make organs, organs make systems and the systems make the body.

A long time ago …

• A couple thousand years ago, people

could not study Biology like we do today.

They did not have the technology that we

have, but they were smart for their time.

• Aristotle (born in 384 B.C.), a philosopher

and scientist of the ancient times thought

that all substances were compounds of

four elements: earth, water, air and fire.

Aristotle

• \

• He thought for instance that humans were

made of earth, which gave material

strength and weight; fire, which provided

warmth; water, which accounted for blood

and other bodily fluids; and air, which filled

the lungs and provided the breath of life.

Of course, some people were more

earthly, fiery, airy, or watery than others.

• This is a neat idea and we can see why he

may have thought these things.

• What do you think we are made of?

• Now with the technology that we have, we

can break matter down smaller than in the

ancient times and we now know that living

things are made of cells.

• This is called Cell Theory – the idea that

cells are the basic unit of structure of

every living thing.

Cells

Red Blood Cells

Sperm Cell

White Blood Cells

Nerve Cells Generalized Cell

Cells

• Cells are the smallest independent units of

life, and all life depends on the many

activities of that cells perform.

• Some basic functions of cells include:

growth, metabolism, and reproduction.

• Cells range from 5 micrometers (sperm) to

more than a meter (some nerve cells).

In the cell …

• The cell is like its own little body that has mini-organs that keep it alive. These include:

• Cytosol – water, proteins, nutrients, waste products, glycogen granules and lipid droplets

• Ribosomes – RNA and proteins

• Mitochondria – proteins and lipids

* These are only some examples

Tissues

• Tissues are made up of many similar cells

that perform a specific function. Tissues

are divided into four groups: epithelial

(skin, linings, protective), connective

(bones and tendons, connects and

supports body), muscle (skeletal, smooth

and cardiac, produces movement) and

nervous (brain, spinal cord and nerves,

responds to stimuli and transmits signals).

Organs

• Organs are a collection of two or more kinds of

tissues that work together to perform a certain

function.

• Example: Stomach

Epithelial tissue lines the stomach to protect it

Smooth muscle tissue churns food

Nervous tissue transmits nerve impulses that

coordinate muscle contractions

Connective tissue holds all other tissues together

Systems

• A group of organs that work together to

perform a major function.

• Example: The respiratory system contains several organs that provide a mechanism

for exchange of oxygen and carbon dioxide between

the outside the body and the blood inside

Systems

• Cardiovascular (heart, blood, blood vessels)

Endocrine (ductless glands)

Nervous (brain, spinal cord,

peripheral nerves, sensory organs)

Muscular (skeletal, smooth,

cardiac)

Integumentary (skin, hair, nails,

sweat and oil glands)

Skeletal (bones and cartilage)

Respiratory (airways, lungs)

Digestive (stomach, intestines,

other digestive structures)

Excretory (kidneys, ureters,

urinary bladder, urethra)

Reproductive (ovaries, testes, reproductive

cells, accessory glands and ducts)

Lymphatic (glands, lymph nodes,

lymph, lymphatic vessels)

Introductory Questions

What are the common structures that make up

all living things?

CELLS

What do you think are the basic materials

involved in the metabolism of all cells?

Food, Oxygen, Carbon Dioxide and Water

What do you think happens when cells use up their food and oxygen before there is time to replenish it?

The cells can not function – death.

Blood Cell

Plant cell

Cancer cell

The "strongest" human muscle

Since three factors affect muscular strength simultaneously and muscles

never work individually, it is misleading to compare strength in individual

muscles, and state that one is the "strongest".

1. lifting a weight - the jaw muscle is the strongest.

2. If "strength" refers to the force exerted by the muscle itself - the

quadriceps femoris or the gluteus maximus.

3. A shorter muscle will be stronger "pound for pound" (i.e., by weight) than

a longer muscle - during childbirth, the uterus exerts 100 to 400 N (25 to

100 lbf) of downward force with each contraction.

4. The external muscles of the eye are large and strong in relation to the

small size and weight of the eyeball. It is frequently said that they are "the

strongest muscles for the job they have to do" and are sometimes claimed

to be "100 times stronger than they need to be."

The statement that "the tongue is the strongest muscle in the body"

appears frequently in lists of surprising facts, but it is difficult to find any

definition of "strength" that would make this statement true. Note that the

tongue consists of eight muscles, not one.

5. The heart has a claim to being the muscle that performs the largest

quantity of physical work in the course of a lifetime.