*Hierarchical Organization of

Multicellular Organisms

7.L.1.3 - Summarize the hierarchical organization of multicellular organisms from cells to tissues to organs

to systems to organisms.

Table of Contents Update

Label your table of contents. We will use headings and subheadings for our new section.

Heading - 7.L.1.3 - Hierarchical Organization of Multicellular Organisms

Subheading (indent) - Vocabulary

Table of Contents Update

Label your table of contents. We will use headings and subheadings for our new section.

Heading - 7.L.1.3 - Hierarchical Organization of Multicellular Organisms

Subheading (indent) – Cells and Tissues

Let’s Engage Your Brain

Human BodyAssessment Probe

*The levels of organization from simplest to most complex are:

*Cells

*Tissues

*Organs

*Organ systems

*Organism

*CellsThe basic unit of structure and function in a living thing. All cells perform the processes that keep humans alive and have specialized functions, like the control center in the nucleus. The cell membrane is the outermost layer.

Most simple level of organization- Ex: Red Blood Cells, Nerve Cells, Bone Cells

*Tissues

A group of specialized cells that work together to perform the same function.

There are four basic types of tissue in the human body: nervous, muscle, epithelial and connective

*Tissues

Muscle tissue (cardiac, smooth, skeletal) contract and shorten, making body parts move.

Nervous tissue directs and controls processes. It carries electrical messages back and forth between the brain and other parts of the body.

*Tissues

Connective tissue – connects all parts of the body and provides support (for example tendons, ligaments, cartilage, bone tissue and fat).

Epithelial tissue covers the surfaces of the body, inside (as lining/covering of internal organs of the digestive system) and outside (as layer of skin to protect what is underneath)

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

Table of Contents Update

Label your table of contents. We will use headings and subheadings for our new section.

Heading - 7.L.1.3 - Hierarchical Organization of Multicellular Organisms

Subheading (indent) – Organs, Organ Systems, and Homeostasis

*OrgansA structure that is composed of different kinds of tissues that work together to perform a specific function.

The job of an organ is generally more complex than that of the tissue.

For example, the heart is made of muscle and connective tissues which functions to pump blood throughout the body. It contains all four types of tissues.

For example, the heart is made of muscle and connective tissues which functions to pump blood throughout the body. It contains all four types of tissues.

For example, the heart is made of muscle and connective tissues which functions to pump blood throughout the body. It contains all four types of tissues.

*Organ SystemsEach organ in your body is part of an organ system, which is a group of two or more organs that work together to perform a major function.

Each organ system has its own function but the systems work together and depend on one another.

There are eleven different organ systems in the human body: circulatory, digestive, endocrine, excretory (urinary), immune, integumentary (skin), muscular, nervous, reproductive, respiratory, and skeletal.

*Organ Systems

*Organ Systems

Definition of Homeostasis

homeo = same; stasis = standingHomeostasis is a state of balance in the body.

What is Homeostasis?

All the systems of the body work together to maintain homeostasis (hoh mee oh STAY sis), the body’s tendency to keep an internal balance. Homeostasis is the process by which an organism’s internal environment is kept stable in spite of changes in the external environment.

IntroductionThe different organ systems work together and depend on one another. You are exposed to ever changing environmental conditions.

For example, you may walk out of an air conditioned room into the hot summer sun. When you ride a bike, you use your muscular and skeletal systems to steer and push the pedals. But you also need your nervous system to direct your arms and legs to move. Your respiratory, digestive, and circulatory systems work together to fuel your muscles with the energy they need. And your excretory system removes the wastes produced while your muscles are hard at work.

IntroductionHowever the cells in your body work best when their surroundings are kept constant. Your body has many mechanisms that keep the cells surroundings constant even though your external environment is changing. This is homeostasis.Homeostasis is very important because when it fails you become ill and may die.

Maintaining Homeostasis

Chemistry is the reason why we must maintain homeostasis. Biochemical (the chemical reactions that occur within us) are vital to life and occur efficiently only within a limited temperature range and at a specific pH.

The body must have good internal communication, using the endocrine and nervous systems, to maintain homeostasis.

Feedback inhibition limits the operation of a system or causes it to shut down when it senses too much of a certain product (such as water, glucose, salt, heat, CO2 etc.)

It will cause the system to “turn back on” when there is too little of this product.

Homeostasis in Action

Changes in temp are detected by thermometer, which feeds info about the actual temp back to thermostat.

Thermostat has been previously set to ideal (set point) value; thermostat compares actual value to set point value and sends signal to furnace.

Furnace fires up and changes the internal temp back toward set point. (Furnace will shut down when thermostat determines actual temp is now higher than set point temp).

To see homeostasis in action, all you have to do is take your temperature when the air is cold. Then, take it again in an overheated room. No matter what the temperature of the air around you, your internal body temperature will be close to 370C. Of course, if you become sick, your body temperature may rise. But when you are well again, it returns to 370C.

Maintaining HomeostasisYour body has various ways of maintaining homeostasis. For example, when you are too cold you shiver. Shivering occurs when muscles rapidly contract and relax. This action produces heat that helps keep you warm. On the other hand when you are warm, you sweat. Both of these processes help your body maintain homeostasis by regulating your temperature.

Homeostasis allows an organism to remain in balance with its environment. If homeostasis is not maintained, it can cause illness and harm or kill organism.

Control of homeostasis

Homeostasis is continually being disrupted by

External stimuli: heat, cold, lack of oxygen,pathogens, toxins

Internal stimuli: Body temperature,Blood pressure, Concentration of water,glucose, salts, oxygen, etc.

Physical and psychological distresses· Disruptions can be mild to severe

Controlling body temp

Animals with a large surface area compared to their volume will lose heat faster than animals with a small surface area.

Cooling the body down.

SweatingWhen your body is hot, sweat glands are stimulated to release sweat.The liquid sweat turns into a gas (it evaporates)To do this, it needs heat.It gets that heat from your skin.As your skin loses heat, it cools down.

Stress and Homeostasis

Sometimes, things can happen to throw off homeostasis. As a result, your heart may beat more rapidly or your breathing may increase. These reactions of your circulatory and respiratory systems are signs of stress. Stress is the reaction of your body to potentially threatening, challenging, or disturbing events.

Think about what happens when you leave the starting line in a bike race. As you pedal, your heart beats faster and your breathing increases. What is happening in your body? First, your endocrine system releases a chemical called adrenaline into your bloodstream. Adrenaline gives you a burst of energy and prepares your body to take action. As you pedal, your muscles work harder and require more oxygen. Oxygen is carried by the circulatory system, so your heart beats even faster to move more blood to your muscles. Your breath comes faster and faster, too, so that more oxygen can get into your body. Your body is experiencing stress.

Stress and Homeostasis

If stress is over quickly, your body soon returns to its normal state. Think about the bike race again. After you cross the finish line, you continue to breathe hard for the next few minutes. Soon, however, your breathing and heart rate return to normal. The level of adrenaline in your blood returns to normal. Thus, homeostasis is restored after just a few minutes of rest.

Control of homeostasis

Homeostasis control system

In order to maintain homeostasis, control system must be able to

· Detect changes from normal inside the body

· Process this information along with other relevant information· Make appropriate adjustments in order to restore body to what it should be

The absolute of Homeostasis

To maintain homeostasis, your body has to be able to do four things:

1) get nutrients and oxygen

2) get rid of wastes

3) keep a certain temperature

4) fight disease, viruses, or bacteria

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

*Show What You Know

Homeostasis is constantly being disrupted by external stimuli, internal stimuli, physical distresses, and psychological distresses.

a) True

b) False

*Show What You Know

To maintain homeostasis, your body has to be able to do four things:

a) reject nutrients and oxygen

b) keep wastes

c) do not keep a certain temperature

d) fight disease, viruses, or bacteria