How many bones and muscles can you name?! Without using your phone or book, name as many as possible. The person with the most CORRECT will get a prize!

Do Now

Muscular/Skeletal System!

To understand the structure of muscle.To explain the components and significance of

the sarcomere.To identify the parts of the neuromuscular

junctionTo explain how muscle contracts.

Objectives

Muscular movement Muscles do work by contracting

skeletal muscles come in antagonistic pairsflexor vs. extensor

contracting = shorteningTendons (t=two!)

connect bone to muscleligaments

connect bone to bone

Composed of skeletal muscle tissue, nervous tissue, blood, and connective tissues.

Skeletal Muscle

Fascia: layers of fibrous connective tissue that separate an individual muscle from adjacent muscles.

Epimysium: tissue closely surrounding muscle

Perimysium: separates muscle tissue into small compartments.

Fascicles: bundles of skeletal muscle fibers

Endomysium: surrounds each fiber within a fascicle.

Connective Tissue Coverings

Structure of striated skeletal muscle

Muscle Fibermuscle cell

divided into sections = sarcomeres

Sarcomerefunctional unit of muscle

contraction alternating bands of

thin (actin) & thick (myosin) protein filaments

Muscle filaments & Sarcomere

Interacting proteinsthin filaments

braided strands actintropomyosintroponin

thick filamentsmyosin

Complete the internet investigation to take a closer look at the sarcomere and discover how muscle contraction occurs!!

Exploring on your own…

Complete the Do Now on the “Unit of Muscle Contraction”

Do Now

To determine the role of actin and myosin in muscle contraction.

To identify the steps of muscle contraction.To explain how the neuromuscular junction

works.

Objectives

Thin filaments: actinComplex of proteins

braid of actin molecules & tropomyosin fiberstropomyosin fibers secured with troponin molecules

Thick filaments: myosinSingle protein

myosin moleculelong protein with globular head

bundle of myosin proteins:globular heads aligned

Myofilament Banding PatternA (dark) band- thick and thin filaments

H zone- region of A band having only thick filamentsM line- bisects H zone

I (light) band- thin filaments onlyZ-band- intersects I band; anchors actin

filaments

Organization of a Skeletal Muscle Fiber

Figure 7-2 b-c

Thick & thin filamentsMyosin tails aligned together & heads pointed away

from center of sarcomere

Interaction of thick & thin filaments

Cross bridges connections formed between myosin heads

(thick filaments) & actin (thin filaments) cause the muscle to shorten (contract)

sarcomere

sarcomere

Skeletal Muscle FibersSliding filament theory

Thin filaments of sarcomere slide toward M

line, alongside thick filaments

The width of the A band remains the same

Z lines move closer together

What am I?

Place where a motor neuron meets a muscle cell

Action potential travels down neuron, stimulates release of acetylcholine from vesicles, received by receptors on muscle cell, action potential is propogated and stimulates contraction.

Neuromuscular Junction

Animation

Skeletal Muscle FibersMuscle Contraction

Is caused by interactions of thick and thin

filaments

Structures of protein molecules determine

interactions

Steps of Contraction1. A. Upon stimulation, Ca2+ binds to receptor

on troponin molecule.

B. The troponin–tropomyosin complex

changes, exposing the active site of actin.

2. The myosin head attaches to actin, forming

a cross-bridge.

Steps of Contraction3. The attached myosin head bends/pivots

towards the sarcomere, and ADP and P are released.

4. The cross- bridges detach when the myosin head binds another ATP molecule.

5. The detached myosin head is reactivated as ATPase splits the ATP and captures the released energy.

Sarcomere Shortening

Figure 7-3

Sarcomere Shortening

*H zone and I bands shorten, NOT A-bands

The Contraction CycleFive Steps of the Contraction Cycle

Exposure of active sites

Formation of cross-bridges

Pivoting of myosin heads

Detachment of cross-bridges

Reactivation of myosin

Molecular Events of the Contraction Process

Figure 7-5

Molecular Events of the Contraction Process

Figure 7-5

Molecular Events of the Contraction Process

Figure 7-5

Molecular Events of the Contraction Process

Figure 7-5

Molecular Events of the Contraction Process

Figure 7-5

Molecular Events of the Contraction Process

Figure 7-5

Put it all together…1

ATP

2

3

4

5

7

6

ATP

Explain what is going on during the contraction of a sarcomere.

Read the beginning of the lab as well as the intro’s to the different activities and answer the following questions:Explain motor unit summation.What is a single contraction of skeletal muscle called?What are the 3 phases of this?What is the different between active and passive

force?What is “treppe”?What is “tetanus”? What causes it? Why must you get

a tetanus shot?

Do Now

To further understand muscle contraction.To observe muscle response to increased

stimulus intensity.To observe treppe, wave summation, and

tetanus.To compare and contrast isometric vs.

isotonic contraction.

Objectives

PhysioEx Excersize 2After answering the questions in the Do Now,

begin the experiment on the physioEx disc on our NEW LAPTOPS!! WOOHOO!!!

The other packet is to help you understand some of the terms they go through in the lab.

You will have today AND tomorrow to work on this and should answer the questions in BOTH packets.

Quiz on sarcomere structure and muscle contraction on FRIDAY!

Lab Activity

Tension ProductionThe all-or-none principle

As a whole, a muscle fiber either contracts

completely or does not contract at all

Number of Muscle Fibers Activated

Recruitment (multiple motor unit

summation)

In a whole muscle or group of muscles,

increasing tension is produced by slowly

increasing the size or number of motor units

stimulated

Motor Units

Figure 7-8

Number of Muscle Fibers ActivatedMuscle tone

The normal tension and firmness of a muscle at

rest

Muscle units actively maintain body position,

without motion

Increasing muscle tone increases metabolic

energy used, even at rest

ATP and Muscle ContractionSustained muscle contraction uses a lot of

ATP energy

Muscles store enough energy to start

contraction

Muscle fibers must manufacture more ATP as

needed

Muscle FatigueWhen muscles can no longer perform a

required activity, they are fatigued

Results of Muscle FatigueMuscle exhaustion and pain

Lack of blood supply

Depletion of glucose and glycogen

Damage to sarcolemma and sarcoplasmic

reticulum

Low pH (lactic acid)

Oxygen DebtOxygen debt:

After exercise or other exertion the body needs more oxygen than usual to normalize metabolic activities

Physical ConditioningMuscle Hypertrophy

Muscle growth from heavy training:Increases diameter of muscle fibersIncreases number of myofibrilsIncreases mitochondria, glycogen reserves

Muscle AtrophyLack of muscle activity:

Reduces muscle size, tone, and powerFibers decrease in size and become weaker

*this can happen to people while they

Origins, Insertions, and ActionsPrimary Action Categories

Prime mover (agonist):Main muscle in an action

Synergist:Helper muscle in an action

Antagonist:Opposed muscle to an action

-Take out your physioEx Labs.-Complete the worksheet using your physioEx lab if necessary.

Do Now

To identify the graphs of different types of muscle contraction.

To identify the different types of bones.To classify bones based on shape.To identify different features of bones.

Objectives

Complete the checklist you were given. Fill in “M” if it is a muscle and “B” if it is a

bone or a feature of a bone.CIRCLE the muscles/bones that you are still

unfamiliar with. Make sure you focus on these today!

Do Now

To identify the bones of the skull as well as the different features found within the skull.

To identify the muscles of the head and be able to explain what movement they are responsible for.

To locate the muscles and bones in the head of a sheep through dissection.

Objectives

EVERYBODY STAND UP!!!

Buchalski Says

?

LabelingThe Anterior view of the skull 1The anterior view of the skull 2Side view skullSuperior view of skullMuscles of Facial Expression (note: you do not

need to know all of these but it is good practice)

* Another good website to explore at home…

Review Activities

Purpose: Compare/contrast the

sheep skull with a human skull.

Review knowledge of tissues.

Identify as many structures as possible.

Dissection

What are some main differences in the sheep skull that you don’t see in the human skull? Why might they be better suited for a sheep?

What tissues are you able to see in the specimen?

If you remove the muscle tissue, what bones are you able to identify?

Questions to think about…

Take a look back at the worksheet you completed for the Do Now Activity… are you able to fill in more of it?

Closing Activity