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!

To understand the structure of muscle. To explain the components and significance of the sarcomere. To identify the parts of the neuromuscular junction To explain how muscle contracts.

Muscles do work by contracting skeletal muscles come in antagonistic pairs flexor vs. extensor contracting = shortening Tendons (t=two!) connect bone to muscle ligaments connect bone to bone

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

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.

Muscle Fiber muscle cell divided into sections = sarcomeres Sarcomere functional unit of muscle contraction alternating bands of thin (actin) & thick (myosin) protein filaments

Interacting proteins thin filaments braided strands actin tropomyosin troponin thick filaments myosin

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

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

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.

Complex of proteins braid of actin molecules & tropomyosin fibers tropomyosin fibers secured with troponin molecules

Single protein myosin molecule long protein with globular head bundle of myosin proteins: globular heads aligned

A (dark) band- thick and thin filaments H zone- region of A band having only thick filaments M line- bisects H zone I (light) band- thin filaments only Z-band- intersects I band; anchors actin filaments

Figure 7-2 b-c

Myosin tails aligned together & heads pointed away from center of sarcomere

Cross bridges connections formed between myosin heads (thick filaments) & actin (thin filaments) cause the muscle to shorten (contract) sarcomere

Sliding 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

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.

Muscle Contraction Is caused by interactions of thick and thin filaments Structures of protein molecules determine interactions

1. A. Upon stimulation, Ca 2+ 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.

3. 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.

Figure 7-3

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

Five Steps of the Contraction Cycle Exposure of active sites Formation of cross-bridges Pivoting of myosin heads Detachment of cross-bridges Reactivation of myosin

Figure 7-5

Put it all together… 1 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?

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.

PhysioEx Excersize 2 After 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!

The all-or-none principle As a whole, a muscle fiber either contracts completely or does not contract at all

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

Figure 7-8

Muscle 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

Sustained muscle contraction uses a lot of ATP energy Muscles store enough energy to start contraction Muscle fibers must manufacture more ATP as needed

When muscles can no longer perform a required activity, they are fatigued Results of Muscle Fatigue Muscle exhaustion and pain Lack of blood supply Depletion of glucose and glycogen Damage to sarcolemma and sarcoplasmic reticulum Low pH (lactic acid)

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

Muscle Hypertrophy Muscle growth from heavy training: Increases diameter of muscle fibers Increases number of myofibrils Increases mitochondria, glycogen reserves Muscle Atrophy Lack of muscle activity: Reduces muscle size, tone, and power Fibers decrease in size and become weaker *this can happen to people while they

Primary 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.

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.

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!

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.

EVERYBODY STAND UP!!!

Labeling The Anterior view of the skull 1 The Anterior view of the skull The anterior view of the skull 2 Side view skull Superior view of skull Muscles of Facial Expression (note: you do not need to know all of these but it is good practice) Muscles of Facial Expression * Another good website to explore at home…Another good website to explore at home…

Purpose: Compare/contrast the sheep skull with a human skull. Review knowledge of tissues. Identify as many structures as possible.

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?

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