Major Lab: A Movable Limb

These are the materials that were used in completing this lab. Not shown are an egg, another type of noodle, some permanent markers, the stapler, and the red exercise shirt that was cut up.



Introduction: This lab is introducing one to the basics of movement. Below you will see two pictures depicting the elbow joint.



Using paper towel rolls, a stapler, pipe cleaners, and a red stretchy shirt, I made a working model of a hinge joint, the elbow joint. This picture is the elbow extended out. As you can see, on the back of the tube is the triceps brachii. In this picture, it is contracted and the tendon is connected at the point of insertion, which is at the ulna. The fabric is loose to show that it is not stretched. On the top is the biceps brachii. This is muscle is relaxed. It is stretched out and the muscle is long. The tendons connect the muscle to the radius.


This picture is of the elbow joint bent. The muscles are working in pairs, as described in an early section. The tricep brachii now is relaxed and stretched out. The bicep is contracted, meaning the muscles have shortened. Under the skin, this is what it looks like, for a clearer picture.



Now that we have the basics, let's jump into one of the muscle cells and look at how actin-myosin fibers make the muscle contract. Remember, the WHOLE muscle contracts, we are just looking at one cell.


First an explanation of the different parts. The orange "zig-zag" on the side is called the Z line. It holds onto the actin filaments and will move in accordance. The pink strips are actin filaments. The blue lines are myosin filaments. The little blue lines coming off of the myosin are the cross-bridges which are vital in muscle movement. This picture is the muscle fiber relaxing. It needs to contract.


What happens are calcium (white puffs) come and attach to troponin on the actin filaments. It then pulls away the tropomyosin to expose the myosin binding sites on the actin.


After that, the cross-bridges perform their "oring" where they reach out, attach to the myosin binding sites, and row. It pulls the actin in and the fibers shorten.

For all of this to happen, a neuron needs to be going to the muscle cell to trigger a contraction.


Here is a picture of a neuron I made out of an egg, spaghetti, and another type of noodle. The egg is represented of a cell body that contains dendrites. The spaghetti is representing the axon and the other noodle, that was colored, is representative of the myelin sheath.



Here is a close up of the cell body.

A close up of the axon with Schwann cells.

What happens here is the transmission of messages. At the top of the neuron would be sensory receptors and the other end would have an axon terminal. The message would travel from the sensory receptors to the axon terminal via the axon. First, there is the action potential.



In this picture, we are inside and right outside of the axon. The blue papers are representative of sodium ions, the pink are potassium ions. In the resting stage, you will see the corresponding blue gate at the top of the axon. It is closed and there is more sodium on the inside than the outside, resulting in a -70mV. When the threshold of a transmitter has been fired, the sodium gates open.



What happens then is the sodium ions go out and potassium ions come in. This results in having a +40 mV. This is the action potential, where messages are going to their effectors. It then returns to the normal resting state.

During this process, is something called propagation. When an action potential is occurring, the message races down the axon. When it is myelinated, it is covered in sections with Schwann cells. The ions cannot pass through this, so they "jump" it. This makes the message move much faster and it does not expend as much energy. The picture below show this.




Conclusion: That concludes how a muscle works. We took a look at the outside, how and where the muscle is attached, which muscle is contracting while the other is relaxing. We then jumped into the muscle cell to see how it actually does contract by way of actin-myosin filaments. Lastly, we took a look at how the message gets sent so the actin-myosin filaments know they need to get moving. I hope you enjoyed!

Lab Two: Muscle Function

Introduction: Welcome to the second lab of the unit. In this lab, I took measurements of my huge muscles, squeezed a ball with a cold hand, and then squeezed it many times in a row. All of this to understand how my muscles work! Enjoy!

For part of the lab, I had to measure my muscle flexed and not flexed. My muscle did not change much in size. :( This is a picture of me taking that measurement.


Then, I had to squeeze a ball for twenty seconds and count the number of squeezes. That information was recorded on a table. Then I submerged my hand in ice water, squeezed again for the same amount of time and recorded that information as well.

Then I squeezed a ball many times in rapid succession to see the effects of muscle fatigue. My special helper, Lady, thought we were playing. I had to tell her this was serious business.

Here is an analysis of my data:

1. What are the three changes you observed in a muscle while it is working? (Contracting)

The first change I observed was the muscle expanded outward when flexed.

The second change was the muscle shortening, which contributes to the expansion.

The last change was they became tired with repetition.

2. What effect did the cold temperature have on the action of your hand muscles? Explain.

The cold temperature had a numbing effect. For me, this gave relief as I have carpel tunnel problems (actually medically diagnosed, not self diagnosed). It did not slow down the movement for me, as it may have with others. When one has carpel tunnel, the carpel tendon in the wrist inflames with action, putting pressure on surrounding veins and arteries which make blood flow constricted.

Temperature	Number of Fists
Normal	42
Ice Water	42

This is a table of the data collected.

3. What effect did fatigue have on the action of your hand muscle? Explain.

Fatigue caused the muscle to react slower as well as causing pain. The muscles are not getting enough oxygen and are using up their ATP energy, which causes the fatigue. The pain is built up because of the acid build up in the muscle.

Trial	Number of Squeezes in 20 Seconds
1	42
2	37
3	38
4	36
5	39
6	36
7	34
8	33
9	33
10	30

This table represents what happened as my muscles became fatigued. I also charted the information.
As you can see, by the graph, my number of squeezes decreased. The numbers on the graph need to be inverted to see the decrease clearly as it starts with 42 and the top is at 30.

Conclusion: At the cellular level, I believe cold and fatigue effect the muscle because of the amount of energy required. The needs to maintain homeostasis in order to continue functioning. When it is cold, it expends energy attempting to warm the area. When it is fatigued, the muscles is using up so much ATP, the cells need to constantly be producing more and more before moving into an anaerobic state that creates cramps!

Skeletal Muscle Fiber Contraction

Introduction: Now for the last section of Unit Three! We are going to be taking a closer look at how a muscle contracts as well as the different parts of a muscle. First, let's look at some vocabulary.

Slide to the left, then slide to the right (vocabulary):

~Sarcolemma: Plasma membrane of muscle fiber; can generate or carry action

Potential along the length

~Sarcoplasmic Reticulum: Endoplasmic Reticulum of muscle that holds calcium

Ions

~T (Transverse) Tubules: Dip down into the cell and come into contact with

Sarcoplasmic reticulum at calcium storage sites

~Myofibrils: Contractile part of the muscle fibers

*Sarcomere: bundle of myofibrils that has two types of protein

Myofilaments

1. Myosin: thick filaments made up of protein

2. Actin: thin filament made up of protein

~Myosin is shaped like a golf club, with the head sticking out (cross-bridge)

*act as ores during contraction

~Actin contains tropomyosin and troponin

Below is a picture from http://www.mhhe.com that shows the structure of a muscle fiber.

Sliding:

From http://www.mhhe.com, here is a picture that gives a general idea as to how a muscle contracts. Continue further to learn more about myosin and actin and what role they play.

1. Muscle is stimulated

2. Impulse travels down a T tubule

3. Calcium is released from the sarcoplasmic reticulum

4. Muscle fiber contracts

5. Myosin, in a way, pulls the actin past it with its “ores,” going through a

Cycling shape change in the presence of calcium

6. The sliding of myosin and actin past each other is called

The sliding filament model

Below is a picture of myosin and actin at work with calcium attaching to it. This picture was found at http://www.niaaa.nih.gov.

7. Uses a lot of energy

8. Energy is extracted in three different ways

a. Fermentation

b. Aerobic in Kreb’s Cycle

c. Anaerobic using creatine; quick way to produce ATP but
can’t do it very long

Control of Muscle Fiber Contraction:

~Neuro-Muscular Junction: Region where an axon terminal approaches a muscle

Fiber; the synaptic cleft separates the axon terminal from the sarcolemma

Of a muscle fiber.

~Axon terminals have synaptic vesicles filled with acetylcholine

~When nerve impulses get to the axon terminal, the synaptic vesicles release

Acetylcholine into the synaptic cleft.

~When acetylcholine is released, it diffuses and binds to receptors in the

Sarcolemma, down T tubules, to the sarcoplasmic reticulum releasing

Calcium, thus ending in sarcomere contraction

Below is the picture of a neuromuscular junction from http://www.shelfieldpeonline.co.uk.




Conclusion: That about wraps it up! Explore further and you will see a simple lab about muscle workings (which turned out a little different for me!) as well as a lab that includes an egg cell body! Enjoy!

Overview of Muscular System

Introduction: Now onto muscles! Let's face it, they are everywhere. Even in our faces! This section is going to introduce you as to the functions of our muscular system, the structure of it and how muscles work together. The picture below, from http://www.medicalook.com, not only shows you our muscular system, but it labels it as well!

*Function of Skeletal Muscles

1. Support the body

2. Make bones move

3. Help maintain a constant body temperature

4. Skeletal muscle contraction assists movement in cardiovascular and lymphatic

Vessels

5. Help protect internal organs and stabilize joints

*Skeletal Muscles of the Body

~Basic Structure

*Well organized

*Contains bundles of skeletal muscle fibers

*Muscles are covered with fascia, a type of connective tissue that extends

Beyond the muscle and becomes a tendon

* Tendon often goes past a joint then anchors a muscle to the bone

Above is a picture of a skeletal muscle with various parts labeled. It was found from http://www.medicalook.com.

~Work in Pairs

*Each muscle is concerned with the movement of only one bone

*Origin of a muscle is on stationary bone, the elbow joint for example, the origin is the scapula.

*Insertion of a muscle is on a moving bone, again, using the elbow joint, the insertion point is on the radius.

*When a muscle contracts, it pulls on tendon at insertion and the bone

Moves

*Muscles contract, they shorten

*Can only pull, cannot push so they work in opposite pairs

*One shortens while the other extends; bicep and tricep are a pair

*“Contraction of many cells makes whole muscle shorten, bringing

About body movements” (Slide 11, Movement)

Conclusion: Those are the basics of the skeletal system. Now it is time to take a closer look at the muscle contraction.

Vocabulary

Introduction: Everything in our world has vocabulary, included the different movements of our body. Synovial joint has also been thrown in there because it is going to be talked about coming up in the muscle sections! All pictures in this section were found at http://content.answers.com.

*Synovial Joint: a joint having a cavity filled with synovial fluid, a lubricant for the joint

Refer to the image below.
Refer to the image below for the rest of the vocabulary section. Not included in the image is the rotation movement. That will be found after the definitions.

*Flexion: joint angle decreases; curling forearm up

*Extension: joint angle increases; uncurling forearm

*Adduction: body part moves toward midline of body; pulling arm into body

*Abduction: body part moves away from midline of body; swinging arm out from body

*Rotation: Body part moves around its own axis; twisting the arm around

*Circumduction: Body part moves so that a cone shape is outlined; circling arm

*Inversion: Sole of foot turns inward; bottom of foot points at other foot

*Eversion: Sole of foot turns outward; bottom of foot faces away from other foot

Conclusion: When going through these terms, I found myself testing out each of the actions. It helped me to remember them, so it might help you as well. Don't forget to look at the pictures! Next, we are going to see what other parts contribute to our ability to make these movements!

Bone Growth, Remodeling, and Repair

Introduction: After taking a look at the skeletal system, let's take a closer look at bones. This section is going to discuss the cells involved in bones, bone growth, remodeling, repair, and the breaking down of bones as well.

Cells Involved:

The picture below is from http://acadameic.kellogg.cc.mi.us. It shows how osteoblasts form and how they may differentiate into an osteocyte. Osteoblasts and osteocytes are what help build bone. Osteoclast does the opposite. It breaks it down, or reabsorbs it.

*Cells involved in bone growth

~Osteoblasts: bone-forming cells

~Osteocytes: mature bone cells from osteoblasts; maintain structure of bone

~Osteoclasts: bone-absorbing cells; break down the bone

Bone Development and Growth:


The above picture, from http://www.personal.psu.edu, demonstrates the different parts of a bone that critical to know.

*Bone Development and Growth

~Ossification: formation of bone

~Intramembranous Ossification:

1. Examples: Flat bones; bones of the skull

2. Bones develop between sheets of fibrous connective tissues

3. Cells from connective tissue cells become osteoblasts

4. Osteoblasts secrete an organic mix

5. The bones harden when calcium salts add to the organic mix, a process

Called calcification

6. Osteoblasts promote calcification

7. Ends in the thin plates of spongy bone which contains red bone marrow

8. Periosteum forms outside of spongy bone and newly derived

osteoblasts further ossification

9. More thin plates form and fuse, becoming compact bone forming a

Bone collar that surrounds the spongy bone

~Endochondral Ossification

1. Most bones of the human skeleton is formed this way

2. Bone replaces cartilaginous by calcified bone matrix

3. Inside, bone formations starts at center the spread to ends

~Final Size

1. Epiphyseal plates (growth plate) close and bone length no longer occurs

The above picture shows a growth plate and was found at http://www.eorthopod.com.

Remodeling:

*Bone Remodeling

~Osteoclasts are constantly breaking down bone

~Osteoblasts reform them in the adult

~As much as 18% of the bone is recycled each year

~Bone remodeling is the process of bone renewal and keeps bones strong

Bone Repair:

For anyone that has broken a bone, they know it is a long process to repair a bone. Here is a picture from http://www.apatech.com that shows how a bone repairs itself.

*Bone Repair

~Four step process that occurs over several months

1. Hematoma: blood clots in the space between broken bones in about

Six to eight hours

2. Fibrocartilaginous Callus: tissue repair begins; fibrocartilaginous

Callus fills space between ends of broken bones for about

Three weeks

3. Bony Callus: Osteoblasts make thin plates of spongy bones and

Convert fibrocartilage callus to a bony callus and joins broken

Bones in about three to four months

4. Remodeling: Osteoblasts build new compact bone, osteoclasts absorb

Spongy bone which creates a new medullary cavity

Osteoporosis:

Osteoporosis is a very serious problem. The picture below shows what a bone with osteoporosis looks like. It was found at http://www.cprevia.com.

~Condition where bones are weakened due to a decrease in the bone mass

That makes up the skeleton

~Bones build until the ones late twenties; by mid to late forties, body begins to

Give back what it has built and bone mass decreases

~Women are more susceptible to osteoporosis

~Leads to fractures

~Milk is not the only source. A great source is broccoli and cauliflower.

~Supplements are not always a great idea because there is not a lot of study

Behind them

~Prevention includes taking in enough calcium during critical bone growth years

And engaging in weight bearing activities

Conclusion: Those are the many steps that a bone grows through. No matter what, when you get older, your bone will eventually give back some of the calcium it acquired. Remember to make sure you get enough calcium and there are definitely more sources than from milk. Now that we understand a little bit more about our bone structure, it is time to take a look at how we move it all around. The next section is very brief and discusses some of the vocabulary used to describe certain motions.

Overview of the Skeletal System

(http://www.stpeters.k12.nf.ca)





Introduction: Welcome to the second part of unit three! This unit is going to look through the skeletal and muscle systems. We are going to start with the skeletal system. This section will delve into the functions of the system, the different types of bones formed, what cartilage is and what it does, as well as the tissues involved. Let's dig in!

Functions:

1. Supports the Body

2. Protects soft body parts

3. Produces blood cells

4. Stores minerals and fat

5. Skeleton, with muscles, permit flexible body movement

Bones:

*Anatomy of a long bone

~Medullary Cavity: Cavity within the diaphysis of a long bone containing

marrow that stores fat

~Diaphysis: Middle length of the bone

~Epiphyses: Expanded region at the end of the bone

~Hyaline (articular) cartilage: Covers end of bones to stop hard bones rubbing

On each other in the joint

~Periosteum: Covers entire long bone (except where hyaline cartilage is) and

Contains blood vessels, lymphatic vessels, and nerves

Now for a look at the compact bone. This picture was found at http://upload.wikimedia.org.

*Compact Bone: Type of bone that is highly organized and composed of

Osteons that house osteocytes in lacunae

Last but not least, is the spongy bone. Above, the picture used for compact bone, also shows spongy bone. It kind of looks like a sponge, huh?

*Spongy Bone: An unorganized appearance containing a lot of trabeculae. Is

Lighter than compact bone and designed for strength

There will be much more on the different types of bones when it gets to the bone formation section. Next, let us look at red bone marrow. The picture below, from http://www.lpch.org is a Earlier in the semester, we talked some about red bone marrow because that is where the red blood cell is made.

*Red Bone Marrow: often fills spongy bones’ spaces; a specialized tissue that

Produces all types of blood cells

Technically, marrow should be placed in the tissues section.

Cartilage:

Cartilage is all over our body. It covers bones and makes part of our nose as well as forms our ear lobes! The below picture is from http://www.botany.uwc.ac.za. It shows the three different types of cartilage.

*Cartilage: Not as strong as bone, but more flexible

~Has gel-like matrix containing collagenous and elastic fibers

~Chondrocytes lie within lacunae that are irregularly grouped

~Has no nerves

~Great for padding joints

~No blood vessels, so it heals slowly

~3 Types

1. Hyaline: Firm, somewhat flexible; found at ends of long bones, nose,

End of ribs, and in larynx and trachea

2. Fibrocartilage: Stronger than Hyaline because matrix has wide rows of

Thick, collagen fibers; withstands tension and pressure; found in

Disks between vertebrae and cartilage of knee

3. Elastic Cartilage: More flexible than Hyaline because matrix has

Mostly elastin fibers; found in ear flaps and epiglottis

Tissues:

Below is a picture from http://www.cartage.org.lb. It simply points out the tibia bone and muscles involved in the foot and toes. It also picks out ligaments and tendons.

*Fibrous Connective Tissue: rows of cells, fibroblasts, separated by bundles of

collagenous fibers; makes up ligaments and tendons

~Ligaments: Connect bone to bone

~Tendons: Connect muscles to bone

Conclusion: That ends the first section of major topic two! Now that we know the basics of the skeletal system, it is time to delve a little deeper. With bones being such a huge part of our body, it is good to know how they are formed, repaired, and sometimes deteriorated.