Physiology Of The Muscular System

Front 1

Sarcolemma

Back 1

outer cell membrane of a muscle fiber (cell)

Front 2

Myofibrils

Back 2

elongated protein strands inside of a muscle fiber (cell)

Front 3

Sarcoplasmic Reticulum

Back 3

smooth ER that fills the clefts/spaces between myofibrils; stores calcium.

Front 4

T-tubules

Back 4

tubular invaginations which serve as a sort of transport system in a muscle fiber (cell); Propagates an action potential to the inside of a cell

Front 5

Dihydropyridine Receptor

Back 5

the physical connections b/t the T0tubues and the sarcoplasmic reticulum

Front 6

If myosin heads are engaged, the muscle is ____________.

Back 6

contracting

Front 7

If myosin heads are NOT engaged, the muscle is _________.

Back 7

relaxed

Front 8

Myosin

Back 8

--thick myofilament
--1500 in one fiber/cell

Front 9

Actin

Back 9

--thin myofilament
--3000 in one fiber/cell

Front 10

Function of Troponin?

Back 10

it masks the binding site on the actin molecule

Front 11

Sarcomere

Back 11

the functional unit of contraction (from Z-line to the next Z-line)

Front 12

meaning of "sarco"

Back 12

flesh

Front 13

meaning of "meros"

Back 13

part or unit

Front 14

meaning of "methel"

Back 14

middle

Front 15

meaning of "hellar"

Back 15

lighter or brighter

Front 16

What happens to allow the myosin head to attach to the actin molecule?

Back 16

Calcium binds to Troponin; Induces a conformational change, which then allows the myosin head to attach

Front 17

Name the 3 properties of skeletal muscle.

Back 17

1--Excitation
2--contraction
3--relaxation

Front 18

Synapse

Back 18

the neuromuscular junction (NMJ) b/t a neuron of one cell and that of a neuron, muscle fiber/cell, or gland cell

Front 19

What is an action potential?

Back 19

a chemical or physical stimulus that causes the depolarization (or influx of sodium ions) into a cell

Front 20

10 SIMPLE steps to Skeletal Muscle Contraction

Back 20

STEP 1:
A nerve impulse travels down and axon and causes the release of acetylcholine.

STEP 2:
Acetylecholine causes the impulse to spread across the surface of the sarcolemma.

STEP 3:
The nerve impulse enters the T Tubules and Sarcoplasmic Reticulum, stimulating the release of calcium ions.

STEP 4:
Calcium ions combine with Troponin, shifting troponin and exposing the myosin binding sites on the actin.

STEP 5:
ATP breaks down ADP + P. The released energy activates the myosin cross bridges and results in the sliding of thin actin myofilament past the thick myosin myofilaments.

STEP 6:
The sliding of the myofilaments draws the Z lines towards each other, the sarcomere shortens, the muscle fibers contract and therefore muscle contracts.

STEP 7:
ACh is inactivated by Acetylcholinesterase, inhibiting the nerve impulse conduction across the sarcolemma.

STEP 8:
Nerve impulse is inhibited, calcium ions are actively transported back into the Sarcoplasmic Reticulum, using the energy from the earlier ATP breakdown.

STEP 9:
The low calcium concentration causes the myosin cross bridges to separate from the think actin myofilaments and the actin myofilaments return to their relaxed position.

STEP 10:
Sarcomeres return to their resting lengths, muscle fibers relax and the muscle relaxes.

Front 21

A SIMPLE explanation of SMOOTH muscle contraction

Back 21

1. Action Potential causes Depolarization of Smooth Muscle Membrane

2. Voltage-Gated Calcium Channels Open

3. Inc Calcium enters cytoplasm

4. Calcium binds Calmodulin

5. MLCK (Myosin Light Chain Kinase) is activated

6. Myosin is phosphorylated and acts on actin forming cross-bridges and contracting

7. MLCP (Myosin Light Chain Phosphatase) is activated

8. Mysoin is dephosphorylated and disassociates from actin causing relaxation

Front 22

What is the purpose of Intercalated Discs found in cardiac muscle?

Back 22

they allow transmission of electrical activity; synctium

Front 23

Define Tetanus. What is the causative agent?

Back 23

--Tetanus is an infection of the nervous system that produces continuous tonic muscle spasms.
--caused by the potentially deadly bacteria Clostridium tetani.

Front 24

Define Botulism. What is the causative agent? Describe its pathogenesis.

Back 24

--Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum.
--The bacteria may enter the body through wounds, or they may live in improperly canned or preserved food.
--acts on NMJ; Toxin prevents vesicles containing ACh at the synapse from release.
--may cause flaccid paralysis due to lack of muscle contraction.

Front 25

Describe Rigor. What is it called upon the ceasement of life?

Back 25

--a continuous contracted state
--a depleted ATP-state; Myosin heads unable to detach; Calciun cannot be sequestered back into the SR by its pump
--upon death, it is referred to as Rigor Mortis

Front 26

Describe Fatigue.

Back 26

--a subjective feeling of tiredness which is distinct from weakness, and has a gradual onset. Unlike weakness, fatigue can be alleviated by periods of rest.
--Fatigue can have physical or mental causes
--function of muscle cells and NOT due to neurons
--a decrease in ATP availability
--an increase in the concentration of metabolites (lactic acid)

Front 27

What 2 metabolic pathways produce ATP?

Back 27

Glycolytic and Oxidative