Unit 3 Ethical Essay: Exercise

Get Out

How can it be? Exercise facilities seem to be popping up on every corner. But you don't need to be an expert to know that obesity is on the rise in our country, not only in adults but in children as well. So why is it on the rise? Because of the way we view exercise.

To start, what does exercise mean? Does it mean dragging yourself to the gym every day and plopping yourself on a treadmill for 20 minutes while you watch TV or read a magazine? Or does it mean throwing a dvd into your player at home and doing 30 minutes of cardio-kickboxing? Neither sounds like much fun to me. How does going for a walk with your spouse sound? Or pushing your kids on the prairie path in the stroller? Maybe today you ride your bike to the video store instead of driving. Then maybe tomorrow you take a walk up into the mountains to get some fresh air and take in a great view. We need to change our perspective on what it means to get exercise.

Secondly, there are a few problems with using exercise - especially exercise at a gym - as a means to achieve the goal of weight loss. First, what happens when you reach your goal? Do you stop exercising? Do you end your membership? Is it fun to be inside, when the weather is beautiful outside? I don't think so. And is exercise fun when the whole point of it is to lose weight? Probably not. Instead of using just weight loss as a goal, what about combining it with things like:

Tomorrow I am going to walk the same distance, but I am going to do it 1 minute faster.
OR
Tomorrow I am going on my hike except I am going to walk 5 minutes past the point where I turned around today.

As you reach these goals, set new ones. And what about combining these small specific goals with more geneneral goals: I want to feel healthy. I want to my lungs to burn a little. I want to feel the burn of lactic acid in my muscles and tomorrow I want my muscles to ache a little. I want to feel invigorated by the cold morning air. I want to feel strong.

Lastly - if at all possible - exercise needs to be a family event and it needs to be outside! The obesity problem in our nation's children is not going to improve unless they learn from their parents the importance of living a healthy lifestyle. There are so many wonderful ways to give your body a workout in the great outdoors. While you are outside getting some exercise, your children can be learning to appreciate the importance and greatness of our National Parks. Especially in the Prescott area, we are so blessed with 1.25 million acres of acres of beautiful National Forest land. And unlike a gym membership, when you excercise outside - you can get in a good workout - for free.
.
So there you have it. We need to change our view about exercise. Forget the gym. Get outside and take your kids. Take in the view. Make it a priority in your family. If you need to lose weight, combine that goal with small specific and big, broad goals. Your body will be happy.

Unit 3 Lab Project: Build a Movable Limb

INTRODUCTION:

The purpose of this lab was to
1. Create a movable limb
2. To demonstrate how muscle action is initiated
3. To demonstrate the process by which the muscle actually contracts

These 3 items were to be built using regular household items. I ended up using 4 models to demonstrate all of the details that were required.

MODEL:
Limb parts listed with materials that represent each.

Movable Limb
Biceps brachii - artificial evergreen branch
Humerus - cinnamon stick
Radius - cinnamon stick
Ulna - cinnamon stick
Capitulum - small, sparkly gold ball covered with masking tape
Trochlea - small gold bell covered with masking tape

Materials:









Building the limb:









A movable limb - as the biceps brachii contracts, the radius (along with the ulna) moves toward the humerus:










Muscle fiber with axon
Sarcolemma - purple plastic wrap
T tubule - thin green paper-coated wire
Myofibrils - glue sticks
Axons - brown pipe cleaners
Schwann cells - oval wooden beads

Materials:









Building the muscle fiber and axon:









The muscle fiber with axons:








Note: After uploading this image, I realized I made a mistake on this one. I should have had one axon with several axon terminals reaching to the 2 muscle fibers.

Lastly, a basic image of one myofibril showing how the individual sarcomeres line up along the length of it:









Sarcomere
Myosin - artificial evergreen limb with masking tape around the center
Myosin head - artificial evergreen needle
Actin - natural jute rope
Troponin - cloth rose
Tropomyosin - gold bead rope
Sarcoplasmic reticulum - green jute rope
Calcium ions - red hearts

Materials:









Building the sarcomere:









The sarcomere:









The sarcoplasmic reticulum in close vicinity to the sarcomere. In the photo on the left, calcium is stored in the sarcoplasmic reticulum. The photo on the right shows the release of the calcium ions from the sarcoplasmic reticulum:









Calcium ions combine with troponin on actin:









Myosin heads attach to actin in the photo on the left. In the photo on the right, the power stroke of the myosin heads moves the actin filaments past the myosin filaments. In this way, the actin filaments approach one another and the sarcomere shortens. As the sarcomeres of a myofibril shorten, the myofibril shortens. This is how a muscle contracts:









Action potential
Axonal membrane - wooden blocks
Sodium ions - white textured balls
Potassium ions - wooden balls
Gated sodium ion channel - green lettered wooden blocks
Gated potassium ion channel - red lettered wooden blocks

Materials:









Resting potential:









Action potential begins as gated sodium ion channels open, sodium ions move from outside of the axon to the inside. The action potential propagates along the axon as the sodium channels open from left to right, sodium move inside the cell, and the inside of the cell changes from -65mV to +40mV. This voltage change also moves from left to right, which is the propagation of the action potential:










Action potential ends as the voltage changes back from +40mV to -65mV. This change happens as the gated potassium ion channels open to allow potassium ions to move from the inside to the outside of the axon. This voltage change also occurs from left to right along the axon:











CONCLUSION
The four models provide above detail several important functions of our body. First, the movable limb model shows how the contraction of a muscle can move a limb around a joint. Second, the model of the muscle fiber shows the basic structures that are involved with muscle contraction. It also lays the groundwork to understand how sliding of the filaments of the sarcomere result in contraction of the muscle fiber. The third model details the structures of the sarcomere and shows how calcium ions are released from the sarcoplasmic reticulum and then combine with troponin on the actin filaments. It also shows how the myosin power stroke slides the actin filaments towards each other to shorten the sarcomere. And the last model illustrates the movement of sodium and potassium ions across the axonal membrane. The movement of these ions contributes to the action potential.

Unit 3, Online Lab #2: Muscle Function

INTRODUCTION:
Sitting upright. Walking. Running. Bending. Stretching. Staying warm. Distributing oxygen. From the simple to the complex, each of these activities requires muscle action. At the core of muscle action are two protein filaments, actin and myosin. Initiation starts in the nervous system and the signal to contract is trasmitted from a motor neuron to a muscle fiber by a neurotransmitter, acetylcholine (ACh). Once ACh diffuses accross the synaptic cleft and binds to receptors in the sarcolemma, an impulse is generated that spreads down into the T tubues to the sarcoplasmic reticulum (SR). This releases calcium ions from the SR, and contraction of the sarcomere is initiated.

The purpose of this lab is to understand how and why temperature and fatigue effect muscle action.

MATERIALS AND METHODS:
Here are pictures of how I performed each part of the lab.

To test the effect of temperature on muscle action, I submerged my hand in ice cold water for one minute (which hurt very bad, I must add!!).
To test the effect of fatigue on muscle action, I squeezed the green ball.
DATA:

ANALYSIS OF DATA:

1. What are the three changes you observed in a muscle while it is working (contracted)?
The relaxed muscle felt soft, the contracted muscle felt hard.
The relaxed muscle was shorter than the contracted muscle.
The circumference of the contracted muscle was larger than that of the relaxed muslce.

2. What effect did the cold temperature have on the action of your hand muscles? Explain.
After submersing my hand in cold water for one minute, I could hardly make a fist. The muscles felt slow and sluggish; it actually hurt a little. It was like the movement of my hand was not working as fast as my brain wanted it to.

3. What effect did fatigue have on the action of your hand muscles? Explain.
By the end of the first set, the speed at which I could contract started to slow down. The squeeze itself also felt alot weaker. The action slowed because my hand started to ache and cramp.

PROBLEMS WITH DATA OR TECHNIQUE:
You will notice in my data for the fatigue trials, that the number of repetitions in the fourth trial was the same as the third trial and that the number of repetitions increased in the 5 trial. This can be explained by the fact that after the fifth trial I realized that my squeezes had gotten very weak. In the sixth trial I concentrated on trying to apply the same force as the squeezes that I performed in the first trial, and noticed that it did take longer compared to when I was not concentrating as much (in the 4th and 5th trials).

I was also using as online counter to time the 20 seconds and I had to reset after each trial. This allowed some time for rest in between each trial.

CONCLUSION:
This lab showed that both temperature and fatigue impact muscle performance. After my hand was submerged in ice cold water, the movement of hand was very slow and sluggish. Similarly, after each set (and after each repetition) the movement of my hand also slowed.

In both instances, the muscles are being asked to work at sub-optimal levels. In cold temperatures, blood vessels and capillaries restrict, reducing the amount of blood flow to the area. With less oxygen being delivered to the area, production of ATP will be slowed. Without plentiful ATP, it will take longer for all of the myosin heads to return to the resting position, increasing the amount of time between power strokes. Diffusion of the ACh across the synaptic cleft probably takes longer and relase of the calcium ions takes more time as well.

The cause of the slowed action while squeezing the ball is most likely due to the buildup of lactic acid. It is toxic to cells and caused the cramping and aching that I felt. The cramping when away once I stopped squeezing and enough oxygen was delivered to the area to allow breakdown of the lactate to pyruvate.

For a visual representation of how a sarcomere contracts, I went to our book. I really like Figure 12.5. It shows the structure of a muscle fiber, and it also shows the sarcomere, in the relaxed position and in the contracted position.










The source of this image is the text for our class:
Mader, Syliva S. Human Biology. New York, NY: McGraw-Hill (2008).
The digital image was downloaded from the power point presentation for Chapter 12 on the Aris website.

This image illustration shows the specific action of actin and myosin. This image was taken from the Owensboro Community & Technical College's Anatomy and Physiology I notes page.

Information in the introduction and conclusion was taken from our textbook:
Mader, Syliva S. Human Biology. New York, NY: McGraw-Hill (2008).

Compendium Review Unit 3 Major Topic: Movement

Movement

I. Skeletal System
II. Muscular System

I. Skeletal System
A. Overview of Skeletal System
1. Functions of the skeleton
a. supports the body
b. protects soft body parts (skull, rib cage, vertebrae)
c. produces blood cells
d. stores minerals and fat
e. permits flexible body movement - along with muscles
2. Anatomy of a long bone
a. diaphysis with medullary cavity - compact bone, endosteum, yellowish bone marrow
b. epiphysis - articular cartilage, spongy bone containg red bone marrow
c. periosteum - covers long bone, is continuous with ligaments and tendons
d. bone
i. compact - osteon - lacunae - osteocyte. canaliculi connect lacunae, run thru matrix
ii. spongy - trabeculae (plates) separated by unequal spaces, filled with red bone marrow. osteocytes irregular placement in trabeculae
e. cartilage - flexible, chondrocytes in irregularly grouped lacunae, no nerves or vessels
i. hyaline cartilage - firm, somewhat flexible, ends of long bones, nose, ends of ribs, larynx, trachea
ii. fibrocartilage - strong, withstand tension & pressure, disk btwn vertebrae, knee
iii. elastic cartilage - more flexible than hyaline, ear flaps, epiglottis
f. fibrous connective tissue
i. ligaments
ii. tendons
Figure 11.1 from the text shows the anatomy of a long bone.











B. Bone Growth, Remodeling, and Repair osteoblasts, osteocytes, osteoclasts
1. Bone development and growth
a. intramembranous ossification - formation of bone developed between sheets of fibrous connective tissue. eg skull
b. endochondral ossification - bone growth occurs as bone replaces the cartilaginous models of the bones
i. cartilage model - chondrocytes lay down cartilage
ii. bone collar - matrix secreted from osteoblasts calcifies, covers diaphysis
iii. primary ossificaton center - osteoblasts in interior lay down spongy bone
iv. medullary cavity & secondary ossification sites - osteoclasts abosorb spongy bone of diaphysis, creates medullary cavity. secondary site form in epiphysis
v. epiphyseal (growth) plate - band of cartilage between primary & each secondary site.
vi. final size - determined when epiphyseal plates close
c. hormones affect bone growth - growth hormone, thyroid hormone,
2. Bone remodeling and its role in homeostasis
a. keeps bone strong, 18% of bone recycled each year
b. allows body to regulate amount of calcium in blood, if blood calcium is high, it can be deposited into bone, if low, calcium removed from bones
c. parathyroid hormone - accelerates bone recycling - increases blood calcium
d. calcitonin - hormone that acts opposite to PTH
e. allows bones to respond to stress -
f. walking, jogging, weight lifting - stimulates work of osteoblasts
3. Bone repair
a. hematoma
b. fibrocartilaginous callus
c. bony callus
d. remodeling
Figure 11.2 from the text illustrates endochondral ossification of a long bone. Additional images from the text can be found here.C. Bones of the Axial Skeleton
Figure 11.7 from the text shows the bones of the human skull.
1. The skull
a. cranium - protects brain, made of 8 bones in adults, some contain sinuses: frontal, parietal, occipital, temporal, sphenoid, ethmoid
b. facial bones
Figure 11.8 from the text shows the facial bones and the hyoid bone.
2. The hyoid bone
a. only bone that does not articulate with another bone
b. attached to temporal bones by muscles & ligaments, to larynx by membrane
c. anchors tongue, site for attachment of muscles associated w/swallowing
3. The vertebral column 33 vertebrae
Figure 11.9 from the text shows the vertebral column.
a. 4 curvatures provide more resilience & strength for upright position
b. protects spinal cord, site of attachment for muscles that move the vertebral column
c. types: cervical, thoracic, lumbar, sacral, coccyx
d. intervertebral disks - fibrocartilage = padding
4. The rib cage protective and flexible
a. composed of the thoracic vertebrae, the ribs & associated cartilages, & sternum
b. the ribs - 12 pairs, all connect to thoracic vertebrae, upper 7 connect w/sternum
c. the sternum - lies in midline of body, with ribs protect heart, lungs
i. composed of manubruim, body, xipoid process
Figure 11.10 from the text shows details of the thoracic verebrae and the rib cage.D. Bones of the Appendicular Skeleton
1. The pectoral girdle and the upper limb flexibility
Figure 11.11 from the text shows the bones of the pectoral girdle and the upper limb.
a. pectoral girdle: scapula, clavicle
b. upper limb: arm - humerus, forearm - radius, ulna, hand - carpals, metacarpals, phalanges
2. The pelvic girdle and lower limb strength
a. pelvic girdle: coxal bones
b. lower limbs: thigh - femur, leg - tibia, fibula, foot - tarsals, metatarsals, phalanges
Figure 11.12 shows the bones of the pelvic girdle and lower limb.E. Articulations
1. Joints
a. cartilaginous - connected by hyaline cartilage (costal cartilages that join ribs to sternum) or by fibrocartilage (intervertebral disks), tend to be movable
b. fibrous - many are immovable (sutures between cranial bones)
c. synovial - freely movable, contain bursa, menisci, synovial fluid
Figure 11.13 from the text shows synovial joints. Figure 11.14 illustrates synovial joint movements.









Definitions for Chapter 11 can be found here.

II. Muscular System
A. Overview of Muscular System
1. Types of muscles
a. smooth muscle fibers - spindle-shaped, uninucleated, form sheets, in walls of hollow internal organs, cause contraction (involuntary) of walls
b. cardiac muslce - forms heart wall, cells generally uninucleated, striated, tubular, branched (allowing interlocking of fibers at intercalated disks), gap junctions in plasma membrane, contraction rhythmical, involuntary
c. skeletal muscle fibers - tubular, multinucleated, striated, attached to skeleton, long - run length of muscle, voluntary
Figure 12.1 from the text shows the 3 types of muscle tissue.2. Functions of skeletal muscles
a. support the body - contraction opposes force of gravity, allows upright
b. make bones move
c. help maintain a constant body temp - heat from breakdown of ATP
d. contraction assists movement in cardiovascular and lymphatic vessels
e. help protect internal organs and stabilize joints
3. Skeletal muscles of the body
a. basic structure
i. fascicles - bundles of skeletal muscle fibers that make up a muscle
ii. connective tissue surrounds both fiber and fascicle
iii. fascia cover muscle and extend beyond muscle to become tendon
b. skeletal muscles work in pairs
i. prime mover - muscle doing most of the work, synergists - assist prime mover, antagonist - muscle that acts opposite to a prime mover
ii. origin & insertion, insertion - contracting muscle pulls on tendons at insertion
4. Names and actions of skeletal muscles
a. size - eg gluteus maximus
b. shape - eg deltoid, trapezius, latissimus, terres
c. location - eg external obliques, pectoralis, gluteus, brachii, sub
d. direction of muscle fibers - eg rectus abdominis, obicularis, trasverse, oblique
e. attachment - eg sternocleidomastoid, brachioradialis
f. number of attachments - eg biceps brachii, quadriceps femoris
g. action - eg extensor digitorum, adductor longus, flexor, masseter, levator
Figure 12.4 from the text shows the superficial skeletal muscles.B. Skeletal Muscle Fiber Contraction
Figure 12.5 shows skeletal muscle fiber structure and function.
1. Muscle fibers and how they slide
a. myofibrils and sarcomeres
i. muscle fibers->myofibrils->sarcomeres->myofilaments=actin & myosin
ii. actin - protein that makes up thin filaments (I band), attached to Z line
iii. myosin - protein that makes up thick filaments (H zone)
iv. action & myosin overlapping make up A band
b. myofilaments
i. thick filaments - several 100 molecules of myosin
ii. thin filaments - 2 intertwining strands of actin, tropomyosin, troponin
iii. sliding filaments - contraction of muscle fiber starts when calcium released from sarcoplasmic reticululm.
iv. sliding filament model - sarcomeres shorten by by actin filaments sliding past myosin filaments. actin fil. approach each other. myosin pull actin
v. ATP (broken down by myosin) supplies energy for muscle contraction
2. Control of muscle fiber contraction
a. nerve impulse reaches axon terminal, synaptic vesicles relase ACh into synaptic cleft
b. ACh binds to receptors in sarcolemma->generates impulses, spread down T tubules
c. sarcoplasmic reticulum releases Ca2+->leads to sarcomere contraction
d. Ca2+ combines with troponin, causes tropomyosin threads to shift, exposing myosin binding site on actin
e. ADP and P on myosin heads attach to actin filament
f. ADP and P are released and cross-briges bend sharply (power stroke)
g. ATP molecules bind to myosin heads, cross-bridges broken, heads detach from actin
h. ATP is hydrolyzed to ADP and P, process starts over, myosin reattaches further
along actin filament
i. cycle recurs until calcium ions are actively (requires ATP) returned to storage site in sarcoplasmic reticulum
Figure 12.6 from the text illustrates the neuromuscular junction and Figure 12.7 shows the function of calcium and myosin in muscle contraction.









C. Whole Muscle Contraction
1. Muscles have motor units
a. varying ratios of innervation - motor axons per muscle fiber (ie 1 motor neuron per 23 muscle fibers in the ocular muscles vs 1:1000 in the gastrocnemius)
b. muschel twitch - occurs when motor unit stimulation is infrequent
c. latent period, contraction period, relaxation period
d. tetanus achieved from summation of rapid series of stimuli
e. recruitment - when more and more muscle units in a muscle are activated upon increased intensity of nervous stimulation
f. muscle tone - when some motor units are always contracted, but not enough to cause movement
1. Energy for muscle contraction
a. fuel source for exercise
i. glycogen & fat stored in muscle
ii. blood glucose & plasma fatty acids
b. sources of ATP for muscle contraction, formation of ATP by:
i. creatine phosphate (CP) - anaerobic, CP pluls ADP = ATP & creatine
- CP formed only when muslce is resting, limited amt stored
- occurs in midst of sliding filaments
- used at beginning of submaximal exercise & during short-term, high-intensity exercise that lasts less than 5 seconds
ii. fermentation - anaerobic
- hormones provide signal to muscle cells to break down glycogen
- fast-acting, results in buildup of lactate
- oxygen debt required to complete metabolism of lactate
iii. cellular respiration - aerobic
- can use glucose from breakdown of glycogen, glucose taken up from blood, fatty acids
2. Fast-twitch and slow-twitch muscle fibers
Figure 12.11 shows fast- and slow-twitch muscle fibers.
a. fast-twitch fibers - (usually) anaerobic, designed for strength
i. motor units contain many fibers, explosions of energy
ii. light color b/c few mitochondria, little or no myoglobin, fewer blood vesssels
iii. vulnerable to accumulation of lactate = fatigue
b. slow-twitch fibers - (mostly) aerobic, more endurance
i. tire only when fuel supply is gone
ii. dark color b/c many mitochondria, contain myoglobin, dense capillary beds
iii. draw more blood & oxygen than fast-twitch
iv. lowe maximum tension, highly resistant to fatigue
v. steady, prolonged production of ATP when oxygen is available
3. Delayed onset of muscle soreness
a. thought to occur with any activity that causes muscles to contract while they are lengthening
b. prevention - warm up, cool down, start gradually with new activity
Figure 12.9 shows the fuel sources for muscle contraction during submaximal exercise (65-75% of effort) and figure 12.10 shows the 3 ways that muscles product ATP.










D. Muscular Disorders see definitions
1. Common muscular conditions
a. spasms, convulsions, cramps, facial tics, strain, sprain
b. tendinitis and bursitis
2. Muscular diseases
a. myalgia and fibromyalgia
b. muscular dystrophy
c. myasthenia gravis
d. amyotrophic lateral sclerosis
E. Homeostasis
1. Both systems produce movement
a. movement essential to maintaining homeostasis
b. skeletal & muscular systems work together to enable body movement
c. allow us to respond to changes in environment
d. other movements contribute to homeostasis - chewing food, contractions of peristalsis, beating of heart, movement aids in venous return
2. Both systems protecy body parts
3. Bones store and release calcium
4. Blood cells produced in bones
5. Muscles help maintain body temperature
Figure 12.12 shows how systems of the human body work together.

Definitions from Chapter 12 can be found here.

REFERENCES:
Mader, Syliva S. Human Biology. New York, NY: McGraw-Hill (2008).

Links provided throughout the summary take you to online sources.


IMPORTANT NOTE: Any time "text" or "the text" is referenced in the above summary, I am referring to the textbook Human Biology by Sylvia Mader (cited directly above).