Anatomy

Front 1

Neural connection between brain & voluntary muscles

Back 1

An action potential starts from the brain to signal skeletal muscle contraction. Action potentials continue along a motor neuron to the muscle cell.

Front 2

Neuromuscular junction

Back 2

A chemical synapse between the motor neuron membrane (synaptic end bulb) and the muscle membrane (sacrolemma)

Front 3

Synaptic cleft

Back 3

Physical space that seperates the two cell membranes

Front 4

Function of acetylcholine

Back 4

Neurotransmitter chemical that carries the information from the muscle cell to the neuron across the synaptic cleft

Front 5

What affect does depolarization have on the motor end plate once action potentials arrive at the synaptic end bulb?

Back 5

This change in voltage opens voltage-gated calcium channels allowing calcium to flood into the neuron

Front 6

What is the affect of increased calcium within the neuron?

Back 6

Causes synaptic vesicles to fuse with the neuron membrane, and acetylcholine is then released into the synaptic cleft

Front 7

What affect does acetylcholine have on the sarcolemma?

Back 7

It triggers the opening of sodium channels resulting in the rapid entry of sodium into the muscle cell

Front 8

What affect do increased sodium ions have on the muscle cell?

Back 8

It depolarizes the sarcolemma and generates a muscle action potential that travels along the membrane

Front 9

Once an action potential goes down a
T-tubule, what affect does it have on the terminal cisterns of the sarcoplasmic reticulum?

Back 9

It causes changes in the terminal cisterns of the SR.

Front 10

What is the function of the ligand-gates calcium channels?

Back 10

Releases calcium ions into the cytosol

Front 11

Define a sarcomere

Back 11

It is the smallest contractile unit where contractile proteins are organized in a specific arrangement

Front 12

What is the role of tropnin and tropomyosin?

Back 12

During periods of rest, troponin blocks the actin binding sites on tropomyosin and prevent the filaments from attaching (and, therefore, the entire cell from contracting)

Front 13

What affect does calcium have on troponin and tropomyosin? How does this affect the muscle?

Back 13

Calcium binds to the troponin complex and changes its shape. This uncovers the actin binding sites on troponin and allows myosin heads to bind to actin which initiates sarcomere contraction

Front 14

What is the function of acetylcholinesterase?

Back 14

This enzyme breaks down acetylcholine and prevents the generation of multiple muscle action potentials from a single nerve impulse. Another muscle action potential will only occur when a new neuron action potential causes the release of more acetylcholine

Front 15

Ho do declining acetylcholine levels affect the muscle?

Back 15

Decreasing levels of acetylcholine will prevent the generation of another muscle action potential

Front 16

What happenes to the clacium ions that were released from the terminal cisterns?

Back 16

Pumped back into the SR and stored until another action potential occurs

Front 17

How does removal of the calcium ions affect the filaments?

Back 17

Troponin complex will return to its normal configuration and cover the actin binding site on tropomyosin thus preventing further interaction between the actin and myosin filaments, and contraction ends

Front 18

Why is bone tissue called dynamic?

Back 18

It is dynamic because it cycles through, being reduced to its primary components to be reabsorbed into the body and then built up again from these components. This homeostatic process is regulated by the body's requirements at any given moment

Front 19

Describe the process and timing of bone remodeling

Back 19

Bone remodeling starts by having its bone cells (osteclasts) reabsorb its own tissue thereby releasing clacium & other minerals for use throughout the body. When restoring bone tissue, bone cells form new bone, taking minerals from the bloodstream and storing it in the bone matrix.

Front 20

How does remodeling change bone structure in response to slight and heavy stress?

Back 20

Remodeling of bone tissue is dependent upon the demands placed upon it. If an individual leads a sedentary and relaxed lifestyle, bone tissue is reduced and excessive bone matrix is resorbed into the body. In contrast, if an individual leads a physically demanding schedule like that of a professional athlete, then bone mass is increased to handle additional mechanical stress.

Front 21

Describe the composition of the bone matrix

Back 21

Bone matrixis connective tissue that is both dense and resilient. Embedded collagen fibers provide for its resilience while calcium phosphate is responsible for the density and firmness in bone.

Front 22

Bone composition gives it great tensile strength. hat does this mean?

Back 22

The composition of both these fibers with the minerals salts furnishes bone its capacity to withstand pressure along its long axis.

Front 23

Role of Mesenchymal cells

Back 23

Primordial cells from which all connective tissue arise.

Front 24

Role of Osteogenic cells

Back 24

Stem cells of bone derived from mesenchyme and undergo cell division which gives rise to osteoblasts.

Front 25

Role of Osteoblasts

Back 25

Cells that synthesize & secrete osteoid (collagen fibers & other organic material) and begin the calcification of matrix.