Term
| What does excitation-contraction (E-C) refer to? |
|
Definition
| events from the action potential in the muscle cell through the iniation and termination of crossbridge cycling |
|
|
Term
| Where are the terminal cisternae found? |
|
Definition
| At the AI junction on a myofribril |
|
|
Term
|
Definition
| invaginations of sarcolemma containing fluid similar to extracellular fluid |
|
|
Term
Transverse tubular system (T-system):
1. it is continuous with the _____
2. it contains _____ materials
3. small/large volume
4. intimately associated with the ______ around each myofibril to ____ activation time |
|
Definition
1. sarcolemma
2. extracellular
3. small
4. sarcoplasmic reticulum, decreases |
|
|
Term
Sarcoplasmic Reticulum
1. surrounds each _____ making up a small volume of the cell
2. it has _____ and terminal cisternae which contains ______
3. The SR membrane consists of _____ and ____ is released after depolarization of the transverse tubular membrane |
|
Definition
1. myofibril
2. longitudinal reticulum, Ca
3. Ca pumps, Ca |
|
|
Term
| How is skeletal muscle different than cardiac muscle in regards to Ca storage? |
|
Definition
skeletal - stored in the muscle
cardiac - takes ca from outside |
|
|
Term
| calsequestrin; same function as calreticulin |
|
Definition
| stores Ca in the terminal cisternae; has a low affinity but high capacity for Ca and lowers free Ca in the terminal cisternae |
|
|
Term
| ____ is the receptor (junctional tetrad) that is the voltage sensor for ECC. when the action potential reaches this receptor membrane charge moves into the T system and intitiates release of ___ into the SR dependent on the T-system membrane potential of ___ to ___mv. |
|
Definition
| DHPR (dihydropyridine receptor), Ca, -50 to -20 mV |
|
|
Term
| When does relaxation of the muscle occur? |
|
Definition
| when Ca is no longer bound to troponin C |
|
|
Term
| Where is the site of Ca storage in the SR? |
|
Definition
|
|
Term
| How is Ca transported back into the SR to relax the muscle and lower cytoplasmic Ca? |
|
Definition
| Ca ATPase transports 2 Ca against the gradient for every ATP hydrolyzed...has a high affinity for Ca |
|
|
Term
| SR feet are coupled to the T-tubule membrane and release Ca through a ____ receptor. DOes it require ATP? |
|
Definition
|
|
Term
| What other thing can cause Ca release? (something we eat/drink) |
|
Definition
|
|
Term
| What makes up the junctional triad in the muscle? WHere is it found? |
|
Definition
1. sarcoplasmic reticulum cisterna
2. transverse tubule
3. sarcoplasmic reticulum cisterna
- junctions of the AI bands |
|
|
Term
Control of skeletal muscle contraction is mainly by Ca:
shown by (3) |
|
Definition
1. ATPase activity of isolated myofibirls
2. stress development in skinned fibers dependent on Ca
3. muscle cells increase Ca concentration on stimulation |
|
|
Term
|
Definition
| membrane potential when contraction is initiated; excitation threshold is around -50 mV |
|
|
Term
| Increases of K+ causes ____ |
|
Definition
|
|
Term
| The mechanical activation of muscle occurs between ___ and ___ mV |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| produces a complete contraction; temporal summation of action potentials to produce maximal force/contration |
|
|
Term
|
Definition
found in the mdg mouse
- NO EC coupling
- lacks functional voltage sensor for ECC
- mouse lived when given caffeine |
|
|
Term
Malignant Hyperthermia
- due to induction ____ and ____
- causes ______
death in ____% of cases
-what causes the hyperthermia? |
|
Definition
- rare complication of anesthesia
- succinylcholine and halothane
- causes muscle stiffness and rise in body termperature, which increases plasma K+ and induces cardiac failure
- 30-50%
- all skeletal muscles contract and this decreases ATP and increases the amount of heat released - coldness |
|
|
Term
How do we test for malignant hyperthermia?
- what is the defect?
-how is it treated? |
|
Definition
- test with in tact muscle biopsy test to see increased sensitivity to caffeine and halothane
- genetics, defect is a disorder of regulation of Ca linked to abnormal Ryatodine receptors (Ca release channels)
- treat with dantrolene - muscle relaxant blocking Ca release from SR |
|
|
Term
| the muscle sodium channel is a large integral membrane protein complex. A number of toxins are known to interact with this channel and block its function. In the presence of on of these toxins, activation fo which membrane protein would initiate muscel contraction? |
|
Definition
| transverse tubular voltage sensor |
|
|
Term
| during skeletal muscle relaxation calcium increases in______. |
|
Definition
|
|
Term
| A 38 year old male is evalulate by a neurologist for muscle weakness. As part of the evaluation, he undergoes a muscle biopsy. The electron miscroscopy report returns to your office one week later and states normal except for a marked reduction in junctional tetrads. What would be a consequence of the reduction in junctional tetrads? |
|
Definition
|
|
