Exam Iii: Muscular System

Front 1

A band

Back 1

DARK bands; contain overlapping myosin and actin filaments

Front 2

Acetylcholine (ACh)

Back 2

Neurotransmitter released from the axon terminals of the motor end plate of a motor neuron.

- stimulates a skeletal muscle cell to contract

- docks with ACh receptor in the motor end plate and is finally decomposed with the help of acetylcholinesterase

Front 3

Actin

Back 3

"Thin filaments"

actin filament is a double stranded chain of actin molecules. Each actin molecule is a spherical protein that is the repeated unit in an actin filament.

- Has two other proteins associated with it:

1) TM (tropomyosin)

2) TP (troponin)

Front 4

Aponeurosis

Back 4

a flat sheet of pearly-white fibrous connective tissue that takes the place of a tendon in sheet-like muscles having a wide area of attachment.

Ex) epicranial aponeurosis

Front 5

Axon terminal

Back 5

The end of a neuron that resembles a "knob" like structure.

Front 6

Cardiac muscle

Back 6

Muscle ONLY found in the Heart

- tubular structure

- single nucleus per cell

- striations

- intercalated discs: permit one cell to stimulate another to contract, called "cell to cell" communication

Front 7

Disuse atrophy

Back 7

Decrease in muscle mass due to disuse.

- Caused from being bedridden. Proteases (enzymes digest proteins) are activated and actin/myosin are digested, decreasing the size of the muscle cell.

- NOT permanent bc actin/myosin can be remade

- MAIN cause of muscle atrophy

Front 8

Endomysium

Back 8

Connective tissue that surrounds the skeletal muscle cells. Binds one muscle cell to another and insulates the cell for electrical activity

Front 9

Epimysium

Back 9

Tough, fibrous C.T. that surrounds the whole muscle

Front 10

Fascia

Back 10

Fibrous connective tissue that surrounds the outside of the whole muscle

Front 11

Fascicle

Back 11

cluster of skeletal muscle cells

Front 12

Hemoglobin

Back 12

protein pigment: gives cells bright red color in oxygenated form and dark red color in deoxygenated form

- located in red blood cells

Function: transport oxygen to tissues throughout the body.

Front 13

Hypertrophy

Back 13

Increase in muscle mass

Ex) Body builder lifting weights

- Weighted stress causes muscle cells to produce more actin and myosin therapy increasing the size of skeletal muscle cells.

Front 14

I band

Back 14

LIGHT bands; contains ONLY actin filaments

Front 15

Intercalated disc

Back 15

permit one cell tostimulate another to contract. Thisis “cell to cell” communication.

Front 16

Isometric contraction

Back 16

The muscle does NOT change in length and the tension never exceeds the load

Ex) muscles for maintaining posture use isometric contractions

Front 17

Isotonic contraction

Back 17

As the tension increases, the muscle changes in length.

Ex) muscles involved in walking and running involve isotonic contractions

Front 18

Lactate

Back 18

When muscles don't get replenished with oxygen, anaerobic respiration occurs and lactate accummulates.

glucose >> pyruvate >> lactateLeads to muscle fatigue from a buildup of lactate, decrease in Ca in sarcoplasm, depleted creative phosphate, oxygen, glycogen and other nutrients.

Front 19

Ligament

Back 19

Fibrous connective tissue that anchors

bone to bone

Front 20

Motor end plate

Back 20

The pocket or depression in the sarcolemma that receives the axon terminal of the motor neuron. The sarcolemma contains the ACh receptors for the neurotransmitter Acetylcholine and the enzyme acetylcholinesterase.

Front 21

Muscular dystrophy

Back 21

Genetic disease where there is a deterioration of muscles from having a lack of dystrophin (sarcolemma stabilizer)

- The sarcolemma then tears during contraction leading to muscle atrophy and connective tissue build up which destroys the muscle cell.

Treatment: gene and stem cell therapy

Duchenne muscular dystrophy (DMD) = most common.

- death is often associated with muscle weakness in respiratory muscles (intercostals and diaphragm)

- Women are usually carriers and men contract the disease.

Front 22

Myasthenia gravis

Back 22

Autoimmune disease that targets the neuromuscular junction.

- Antibodies block ACh receptor sites, so ACh cannot bind.

- Leads to paralysis; drooping eyelids, difficulty swallowing and walking >>gen. muscle weakness.

Treatment: Acetylcholinesterase inhibitors and immunosuppressants.

Front 23

Myofibril

Back 23

cluster of myosin and actin protein filaments

Front 24

Myoglobin

Back 24

protein pigment: gives skeletal muscle its reddish color along with the hemoglobin in the blood

- located in skeletal muscle cells

Function: temporarily stores oxygen as a reserve for cellular respiration

Front 25

Myosin

Back 25

"Thick filaments"

- myosin filament cluster of about 200 myosin molecules

- myosin head consists of 2 heads and one long tail. Each head has 2 binding sites

1) Actin binding site

2) ATP binding site

Front 26

Neuromuscular junction

Back 26

a junction between nerve and muscle; it is a chemical synapse formed by the contact between the presynaptic terminal of a motor neuron and the postsynaptic membrane of a muscle fiber.

Front 27

Perimysium

Back 27

Connective tissue that surrounds each fascicle.

Front 28

Rigor mortis

Back 28

Stiffening of muscles that begin 3-4 hrs after death. Hits peak rigidity at 12hrs. Then later dissipates, leading to flaccid muscle tone.

How: dying cells have influx of Ca; leading myosin heads to attach when breathing stops. ATP synthesis stops. Myosin heads therefor cannot detach. Flaccidness comes as proteases digest actin/myosin.

Front 29

Sarcolemma

Back 29

Sheath that surrounds the muscle.

a.k.a. Plasma membrane of skeletal muscle cell

Front 30

Sarcomere

Back 30

The regional area between two Z-lines (discs); also, the functional unit for muscle contraction

Front 31

Sarcoplasm

Back 31

cytoplasm of skeletal muscle cell

Front 32

Sarcoplasmic reticulum (S.R.)

Back 32

muscle tissue's version of the E.R.

- an elaborate network thats more extensive compared to other cells

f(x): stores Ca++ ions

- contains specialized regions called triads

( 3 structures): 2 outer T-tubules and middle terminal cisternae

1) T (transverse) tubules: function is to conduct nervous impulses to every single region of the muscle cell.

2) Terminal cisternae: site where calcium is released from the SR to the surrounding sarcoplasm

Front 33

Skeletal muscle

Back 33

all major muscles throughout the body

- striated

- voluntary

Front 34

Smooth muscle

Back 34

Involuntary

- found in digestive tract, blood vessels, respiratory system, etc.

- smaller, flatter cells

- single nucleus per cell

- no striations

- cells often stack on top of each other to form a sheet

Front 35

Synapse

Back 35

a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

Front 36

Tendon

Back 36

"cable-like" structure

Fibrous connective tissue that anchors muscle to bone.

Front 37

Tropomyosin (TM)

Back 37

Regulates binding of myosin head

- bound with troponin, TM slides back and forth over the actin filaments.

- It can either be OPEN (exposing myosin binding sites) or CLOSED (covering binding sites).

- Movement to the OPEN state requires Calcium to bind to Troponin.

Front 38

Troponin (TP)

Back 38

Bound to Tropomyosin to form TM/TP complex.

- When Calcium binds to troponin, it allows the TM/TP complex to slide OPEN, exposing the myosin binding sites.