Chapter 22: Body Organization and Structure



Chapter 22: Body Organization and Structure

Section 1: Body Organization

Recall: The maintenance of a stable internal environment is called homeostasis. If homeostasis is not maintained, cells are often damaged and can die from the damage. These cells make up tissues, so in effect the tissues can die and as the organization levels occur, the organism can ultimately die.

Tissue Types

There are four types of tissue: 1) Epithelial Tissue – this tissue covers and protects underlying tissue 2) Nervous Tissue – this tissue sends electrical signals from the point of a stimulus to the brain in order to react to the stimulus if necessary 3) Skeletal Muscle Tissue – this tissue is made of cells capable of contracting and relaxing that can produce movement within or of our body 4) Connective Tissue – this tissue joins, supports, protects, insulates, nourishes, and cushions organs and keeps organs from falling apart.

Recall that two or more tissues working together will form an organ. Our stomach has all four types of tissues that make it up (the stomach therefore is an organ). The stomach has blood vessels which is connective tissue, it contains epithelial tissue to cover the lining, it has nervous tissue (tell us when we are hungry or full), and it contains muscle tissue that expands and contracts to break up the food we ingest (eat).

Recall organs make up organ systems. When any organ fails, the body’s organ systems can fail. We have 11 organ systems.

The 11 Organ Systems (We will look at these in great detail)

1: Integumentary System – made up of our skin, hair and nails. This system helps protect underlying tissue(s).

2: Muscular System – Your skeletal muscles move your bones and this allows us to move from one place to another if our body is functioning properly.

3: Skeletal System – this is made up of your bones. Our bones provide support. If we didn’t have bones we would be one ugly blob with no shape.

4: Cardiovascular System – composed of our heart, and blood vessels (arteries and veins). Transports blood with nutrients and wastes.

5: Nervous System – this system sends electrical impulses throughout our body (nerves, spinal cord, and brain).

6: Lymphatic System – this system includes lymph nodes and lymph vessels and helps us with immunity and getting rid of germs.

7: Digestive System – Breaks down food we eat into nutrients that our body can use.

8: Endocrine System – Composed of glands that secrete hormones (chemical messages) for specific actions in our body (pituitary gland, thyroid gland and testies for males, and ovaries for females to name a few of the glands in our body).

9: Respiratory System – our lungs absorb oxygen and release carbon dioxide.

10: Urinary System – removes wastes from our blood and regulates fluids in our body.

11: Reproductive System: In males it produces and releases sperm. In females it produces eggs and provides a development site for an unborn baby.

Review

1. Explain the organization level and relationship between cells, tissues, organs, and organ systems.

2. Compare the four types of tissues and their function.

3. Without looking at your notes, make yourself a chart listing all of the major organ systems and their function.

Answers to Review

1. Cells make up tissues, tissues make up organs, organs make up organ systems and organ systems is what make up an organism. Cells work together to make tissues. Tissues work together to make organs. Organs work together to make organ systems. Organ systems make up organisms.

2. Nervous Tissue – sends electrical signals (impulses) for stimuli, Epithelial – covers and lines in order to protect underlying tissue, Muscle – cells contract and expand to produce movement, Connective Tissue – joins, supports, protects, insulates, nourishes, cushions, and keeps organs from falling apart.

3. Compare your chart to the notes you have learned.

Applying what you learned

Think of a time when homeostasis in your body was disrupted. Which body system(s) were affected? Explain your reasoning.

IMPORTANT: As we learn details about each system always make yourself learn the NAME, LOCATION, and FUNCTION. Example: Name: nervous system, Location: spinal cord, nerves, brain, Function: to send electrical impulses for reactions to stimuli or other needed reactions (walking, talking, etc.).

Section 2

The Skeletal System

Our bones and cartilage and the special structures that connect them make up our skeletal system. If we did not have our skeleton for support we would be a mass or blob so to speak. Our skeleton or bones are living cells. They must be nourished because they are made up of cells. These special cells are called osteocytes and they mage up our bone tissue.

Functions of Our Bones

1) Protection - the vital organs in our chest (heart and lungs) are protected with our ribs, our spinal cord is protected by our vertebrae, and our brain is protected by our skull.

2) Storage - bones store minerals that help the nerves and muscles function properly. Your arm and leg bones store fat that can be used for energy.

3) Movement – Muscles pull on the skeleton in specific locations to produce movement. Without the bones we also could not sit, stand, walk, or run.

4) Blood Cell Formation – Some of our bones are filled with marrow that produces blood cells.

Bone is composed of connective tissue and minerals that are deposited by living cells called osteoblasts. If we looked at a section of our longest bone (the femur) in our thigh, we would find spongy bone and compact bone. These are found in all of our long bones. Compact bone is dense and has no visible openings. Spongy bone appears to look like a real fine sponge with air spaces. Spongy bone is where we get most of the strength for our bones. The “spongy” configuration acts as a truss structure analogous to what we would see in a building made of steel.

Marrow

The soft tissue in the bone is called marrow and red marrow produces red blood cells.Yellow marrow found in the center of the bone (central canal) of long bones stores fat. The canals in the compact bone contain small blood vessels.

Bone Information

Most bones start out as soft, flexible tissue called cartilage. As a new born baby, we had very little bone. We were mostly cartilage. As we became older, the cartilage was replaced by bone.

The location where two or more bones connect is called a joint. These joints have unique designs that will allow movement from some joints and little or no movement from others. Joints that are freely moving are more susceptible to injury than those that are less flexible.

Joints are held together by ligaments that are connecting bone to bone. A strained ligament will heal if given time, but a torn ligament must be repaired surgically. Most bones also have cartilage on the ends to help cushion the area where two bones meet. When this cartilage is worn away, the joint becomes arthritic. This can create discomfort for the individual with arthritis.

Types of Joints

1. Sliding Joint – this type of joint allows some movement of flexibility. The bones in this type of joint glide over each other. Example: the bones in your wrist.

2. Ball and Socket – this operates like a joystick on a computer game, the joint is free to move in all directions. Example: your shoulder joint.

3. Hinge Joint – this operates like a hinge on a door. Example: Knee joint, knuckles, toes, jaw and elbow joint.

How Bones Function to Help Movement

Bones function like a simple machine called a lever. The lever has three parts: fulcrum, effort, and the load. The effort is the force applied to the lever, the fulcrum is the pivot point and the load is the resistance. There are three classes of levers:

First Class Levers: have the effort on one end, the load on the other with the load on the other and the fulcrum located in the middle.

Effort Fulcrum Load

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Example: Your neck serves as the fulcrum and the muscles on the back of your neck serve as the effort to tilt your head back (upward), the load would be the front of your head (face region).

Second Class Levers – have the fulcrum on one end and the effort on the other with the load close to the effort.

Fulcrum Load Effort

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Example: If you raise your heel off of the floor, your toes are the fulcrum and the effort is the muscles on the back of your leg, the load is the “weight” exerted from your body to the middle or arch portion of your foot.

Third Class Lever – the effort lies between the load and fulcrum.

___________________________Effort Load

/\ (Fulcrum)

Example: Holding your forearm parallel to the floor and having your upper arm 90 degrees to the floor. While doing this imagine having something in your open hand like a cup. Your elbow serves as the fulcrum and the muscles on your forearm serve as the effort while lifting the cup with your hand and holding the rest of your arm stationary.

Review

1. What are the important functions of bones?

2. Draw a long bone like a femur that has a section removed and label the parts (spongy bone, compact bone, areas for blood vessels, marrow cavity, and cartilage).

3. List three hinge joints in your body.

4. Are bones living? What do bones begin as? What do we call the cells that deposit bones? Where are red blood cells produced? Some bones store fat, what is it used for?

5. What is a function of cartilage on the ends of bones?

Answers

1. Bones provide support, store and release minerals, enables us to move our bodies, and make blood cells.

2. Compare your drawing to the bone on page 527 in our classroom text.

3. Hinge joints can include the elbow, knee, jaw, knuckles and toes.

4. Bones are living, they require nourishment like other tissues in our body. Bones start out as cartilage. The cells that deposit bones are called osteoblasts. Red blood cells are produced in the red marrow. The fat can be used as a source for energy.

5. Cartilage can serve as a cushioning source when it is located at the end of long bones.

Section 3

The Muscular System

Muscles attach to bones and the connective tissue that attaches them make up the muscular system. Remember: Muscles ALWAYS contract to do work. In other words, for muscles to do work, the muscle fiber must contract (get shorter).

Types of Muscle Tissues

1) Smooth Muscle – this is found in the digestive tract and your blood vessels. 2) Cardiac Muscle – this is heart muscle (found only in the muscle tissues of your heart). 3) Skeletal Muscles – these are the muscles attached to your bones for movement and protecting inner organs.

Voluntary or Involuntary Muscle

Muscles that are under your control are voluntary muscles. The muscles used to pick up a pencil when you want to write are voluntary muscles (you are controlling their actions). Muscles that digest food, move food through your digestive system (smooth) and cardiac muscles are examples of involuntary muscles (you do not have to think about making these muscles take action).

Some may fall into voluntary and involuntary (example: eyelids – sometimes you control your blinking, other times you blink and do not realize you have blinked).

Working Muscles

When you want your muscles to contract and make you walk you must have electrical signals traveling from your brain to your muscle cells. The muscle cells respond by contracting (shortening). Remember, muscles only do work when their fibers are contracting.

Muscles to Bones

Your skeletal muscles are attached to your bones by a connective tissue called tendons. When the muscles contract, they get shorter and bring the bones closer to each other, hence producing movement.

Muscles always work in Pairs

Muscles work in pairs, resulting in smooth controlled movements. Example: Your Biceps (upper arm muscle in the front) can contract and cause our arm to bend at our elbow. The triceps (back of upper arm) can contract to straighten our arm back out. The muscle that is causing the bending movement is called the flexor, and the muscle that straightens out a part of the body is called the extensor. So in the above example, the biceps is the flexor and the triceps is the extensor.

Use It or Lose It

If you do not use your muscles, the muscle tissue will deteriorate. We must use our muscles in order to keep them “tone” and in order to build them up and become stronger. If you know someone with a broken bone and they wear a cast, the muscles not being used will become weaker and will have to be strengthened when the cast is removed.

Muscles also aid in the circulation of blood and lymphatic fluid. When muscles contract, the action constricts the vessels and “pushes” blood and lymph in their respected vessels. This helps blood flow without extra effort from the heart.

Exercise

In order to maintain muscle or build muscle, we have to be active and exercise. The most effective exercise is resistance exercise. This is where the muscle contracts to move an object and the object offers resistance. The process of lifting our bodies vertically offers one method of resistance. An example of this type of exercise would include climbing steps, push-ups, sit-ups, pull-ups and other motions that use our own weight as the resistance weight. Resistance exercises are often hard to maintain long periods of time, but they offer one of the best methods of building muscle.

Aerobic Exercise

Aerobic – with oxygen. Aerobic exercise is great for our cardiovascular system. This strengthens the heart muscle and will increase the lung capacity and the effectiveness of our lungs. Aerobic exercises do not necessarily strengthen skeletal muscles, but increases our endurance.

Damaging Muscle Tissue

Before taking part in any physical exercise program, our muscles need to be warmed and stretched. Stretching can do this. Taking in deep breaths while stretching also increases the oxygen content in our bodies. After stretching and giving our muscles a warm-up reduces the chance for a muscle injury. When we “pull a muscle” we may be straining it or the muscle fibers can actually tear. We can also damage tendons. The tendons can become inflamed (irritated) and the area may feel warmer than the surrounding tissue. This type of tendon injury is called tendonitis.

Anabolic Steroid Use

This has become all too common in the area of sports. Taking the anabolic steroids can make our muscles larger and stronger and gives many athletes an unfair advantage. We are now seeing the effects of using anabolic steroids. Many athletes have died from having an enlarged heart as well as other complications from using anabolic steroids. If a person has not fully developed it may also cause bones to stop growing, high blood pressure, kidney failure and liver and heart problems. Anyone taking these steroids are at risk for an early death or a very unhealthy life due to the negative affects.

Review

1: What are the three types of muscle tissue and give a few locations you can find each type. Give the main functions of each type of muscle tissue.

2: What are the differences and similarities between resistance and aerobic exercising and give a few examples of each. Can they both be the same in certain instances?

3: Describe or explain how the muscles in your arm allow you to pick up a glass from a table to your mouth for a drink.

Answers:

1: Smooth muscle tissue helps move materials through the digestive tract and blood vessels; cardiac muscles cause the heart to beat; and skeletal muscles enables bones to move.

2: Resistance exercises increase our strength of skeletal muscles. Resistance exercises involve overcoming weight of some type. Aerobic exercises improve the condition of heart muscle and increase our endurance.

3: Our biceps contract in order for our arm to bend and bring the glass up to our mouth to drink. Our triceps contract in order to straighten our arm back out and set the drink back onto the table.

Section 4

The Integumentary System

The integumentary system is for protection and includes our hair, nails, and skin. Our skin is the largest organ of all the organs our bodies have. Integumentary means covering. The integumentary system also helps your body to maintain homeostasis. Remember from chapter 1: homeostasis is a stable internal environment.

Functions of the Skin

1) Protects our bodies from evaporation and helps keep foreign particles out of the body.

2) Keeps us in “touch” with our environment. The nerve endings in our skin allow us to fell what is around us.

3) Our skin helps to maintain our body temperature. We have sweat glands in our skin that will sweat and when the sweat evaporates, it cools our body.

4) Our skin also helps rid our bodies of waste products from the blood stream by way of the sweat.

Skin Color

A pigment in our skin called melanin determines the color of our skin. If we have a lot of melanin, our skin is very dark. If a small amount of melanin is produced, our skin will be very light. Melanin in the upper layer of the skin protects us by absorbing much of the ultraviolet radiation from the sun, which reduces the DNA damage that can lead to cancer. All of our skin is susceptible to cancer so protection should be taken when we spend time outside. Proper skin suntan lotion should be used and the lotion should contain a SPF protection of at least 30.

Layers of Skin

The skin is the largest organ of our body and it has two layers. The epidermis is the upper layer and is thinner than the second layer. “Epi” means above or top. The deeper layer is called the dermis. It is thicker than the epidermis.

Epidermis

Composed of epithelial tissue. It is about as thick as two pieces of notebook paper over the most of our body. Our palms of our hands and soles of our feet have thicker layers of epidermal cells. Most epidermal cells are dead and filled with keratin which helps the skin be tough and water-proof.

Dermis

Found beneath the epidermis. It contains many connective tissue fibers called collagen. This provides strength and allows the skin to bend without tearing.

Hair and Nails

Hair is grown from the hair follicle and the portion we see is actually dead cells. As hair grows from the follicle, cells are pushed up and form the portion we see.

Hair protects us from ultraviolet radiation and also helps keep dust and other particles out of our eyes and nose. Hair also helps maintain internal body temperature. Many mammals rely on their hair to keep them warm in very cold climates. Humans form “goose bumps” on our skin when we get cold. This occurs when a muscle connected close to the hair follicle contracts and the hair stands up in an erect position. The erected hairs act like a sweater to trap heat which warms the body.

Our nails protect the ends of our toes and fingers so they can remain sensitive to touch. Our nails grow from nail roots. The nails we see are dead cells. As cells grow from the root, the nail gets longer.

Skin Cancer and other Problems

Sometimes skin cells become damaged and the cells rapidly multiply out of control. When cells go through the cell cycle at a rate faster than normal we call that cancer. This can also invade other tissues and result in cancer spreading.

A common problem many individuals face is having hormones cause too much oil being produced by the skin cell oil glands and creating a situation for infections. The oil may cause skin cells and bacteria to clog up the follicle and when the bacteria multiply you have an infection. Washing our skin well each day can usually prevent this type of infection.

REVIEW

1: Why does skin color vary from person to person?

2: List as many structures as you can that are found in the skin and give the function of each one.

ANSWERS

1: The amount of melanin produced regulated the skin color.

2: Hair follicle, blood vessels, nerves, oil glands, sweat glands, keratin for water proofing and flexibility, fat cells to help conserve temperature and can be used as energy sources if needed.

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