Tuesday, April 15, 2008
Major Lab: A Movable Limb
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
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 |
| 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
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
*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
*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
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.
Monday, April 14, 2008
Overview of the Skeletal System
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:
*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.Table of Contents: Part Two
Overview of the Skeletal System
~Functions
~Bone
~Cartilage
~Tissues
Bone Growth, Remodeling, and Repair
~Cells Involved
~Bone Development and Growth
~Remodeling
~Repair
~Osteoporosis
Vocabulary
Overview of Muscular System
~Function
~Structure
~Working Together
Skeletal Muscle Fiber Contraction
~Slide to the left, then slide to the right (vocabulary)
~Sliding
~Control of Muscle Fiber Contraction
Lab Two: Muscle Function
Lab One: Leech Neurons
While it is very, very hard to see, this picture is when found the neuron using the manipulator with the oscillope trace. You can see a vertical "blip" on the screen in the upper left hand corner. That "blip" is the electric pulse which let me know I had located a cell.
From there, I injected it with a dye which would make it visible under an ultra-violet light. I then turned on the ultra-violet light and the neuron was visible.
Using different tools, such as a feather and foreceps, I poked the cell to see what kind of response it would invoke. I took that data, as well as the ultra-violet image, and determined it was a dyed "R" cell.
Here are my responses to the questions asked.
1. What is the electrode measuring?
The electrode is measuring the voltage inside of the cell; the transmembrane potential, also known as the membrane potential.
2. Why use leeches in neurophysiology experiments?
Leeches are used because they have a small number of neurons but those neurons are large in size. Also, no one seems to mind opening one up.
3. What is the difference between a sensory and a motor neuron?
Sensory neurons send information from ORGANS to the CENTRAL NERVOUS SYSTEM. They also have long dendrites and short axons. Motor neurons are the exact opposite. They send information from the CENTRAL NERVOUS SYSTEM to the organs. They also have short dendrites and long axons.
4. Do you think a leech experiences pain? What is pain?
~Yes, I do think leeches feel pain. They do have a brain, nerve cord, and ganglia. They clearly have neurons that transmit messages. Basically, they have all of the parts required to feel pain. They also have sensory organs on the head and body surface which enable them to detect light, temperature, and vibration.
~Pain is an uncomfortable feeling detected by sensory receptors sensitive to chemicals released by damaged tissues or excess stimuli of heat or pressure.
5. What were the two most interesting things about doing this lab?
The two most interesting things for myself were learning more about leeches (I knew next to nothing about them) and the membrane potential, including the voltage inside of cells.
6. Anything you found confusing or didn't like about the lab?
When identifying the cell, no explanation was offered for what the different types of cells meant. I just guessed it was what they reacted to determined which kind of cell they were.
Conclusion: After a hard day of opening up leeches, I think it is time to come to a close. I hope you learned as much as I did in this lab. It was interesting and humorous, with some of the graphics and clicking on things as they cut for you. Had I been attempting this personally, I doubt I would have gotten a neuron!
Senses of Sight, Hearing, and Equilibrium
Sight:
From http://www.scientificpsychic.com, here is a picture labeling all of the different parts of the eye. The next section is going to explain what some of the different parts play in the sight.
*Very Complicated for vision!
*What Happens
~Light comes in
~Focused by Cornea
~Fine focused by lens
~Pupil lets light in
~Iris controls how much light comes in
~Image formed on the retina that receptors respond to
~Rods and cones are the receptors
~Light changes the shape of the protein of rods and cones, thus stimulating
a response
Hearing:
This picture was obtained from http://www.tchain.com. This also labels the different parts, but we are now looking at the ear. It shows the outside, which gathers the sound, through the path the sound will eventually travel through.
*Very Complicated for the Ear!
*What Happens
~Sound is gathered by the external part of the ear
~The tympanic membrane vibrates
~3 bones (Hammer, anvil, stirrup) carry vibrations to the inner ear
~Fluid vibrates and the membrane gets it, cochlea, and it triggers neurons
Equilibrium:Equilibrium is a state of balance. It also uses the ear, but the sound takes another path that helps out equilibrium.
*A lot like the Ear
*What Happens
~All the first stuff of the ear
~When the fluid vibrates, it hits little hairs in the ear
~This triggers the neurons and makes one recognize position
Conclusion: That is it! You just spent time looking through the nervous system, different receptors, as well many other aspects that play vital roles in our lives...that we hardly know about! Next up, we will find out we do things completely involuntary. The second major topic of unit three is all about movement!
Senses of Taste and Smell
Taste
The below picture is from http://embryology.med.unsw.edu.au. What I like most about this picture is at the bottom where it shows which parts of the tongue sense different tastes. "Umami" is a Japanese word that encompasses "deliciousness."
~Most limited of the head senses, about five different taste sensations
1. Salty
2. Sweet
3. Bitter
4. Bitter
5. Deliciousness
~Receptors on the tongue respond to chemicals in the food
~Brain surveys the overall pattern of incoming sensory impulses
~Takes a “weighted average” of taste messages and makes it the taste you taste
Smell:
The picture below is from http://freda.auyeung.net. It shows that air passages with the red arrows, as well as where the olfactory nerve is, sinuses, and other important parts.
~Flavor from foods comes mostly from smells
~Protein molecules from what one is smelling works in combination
With neurons in skin of the nose
~The olfactory bulbs have direct connections with the emotion and memory
Centers of the limbic system (why smells remind people of things)
~Smoking and age decline number of olfactory cells
Conclusion: That is it! The two are associated because the smelling works with the skin of th nose. I have always found it fascinating that smells make people think of things and have strong associations. Next, we will explore sight, hearing, and equilibrium.Proprioceptors, Cutaneous Receptors, & Pain Receptors
Proprioceptors:
Here is a picture from http://www.pilotfriend.com.
*Proprioceptors
~Mechanoreceptors that gives body position
~Allows one to touch their nose with eyes shut
Cutaneous Receptors:
Yes, this is a picture of the skin, but that is because cutaneous receptors are in the skin. This picture was found at http://upload.wikimedia.org.
*Cutaneous
~Receptors of the skin
~Dermis layer of the skin contains the cutaneous receptors, making the skin
sensitive to touch, pressure, pain, and temperature
Pain Receptors:
Last but not least are the pain receptors (located in the skin). This picture is from http://www.instruct1.cit.cornell.edu.
*Pain Receptors
~Also called nociceptors
~Sensitive to chemicals released by damaged tissue
~Referred pain: stimulation of internal pain receptors is felt as skin pain as well as
internal organs
Conclusion: That concludes a deeper look at some of the receptors in our body. Next up, for the next few, we will be taking a look at the different senses we experience. These are sometimes known as "the five senses." We will not be discussion touch though.