Lab 6 + 7 - Neurophysiology & Neuromuscular Physiology

Question 1

Dendrites

Answer 1

branch from cell body and receive input from other neurons

Question 2

Cell Body

Answer 2

contains nucleus and endoplasmic reticulum
- important for making proteins involved in neurotransmission

Question 3

Axon Hillock

Answer 3

beginning of an axon, initiates action potentials
- -55 mV is threshold
- voltage-gated sodium channels open at threshold
- action potential propagates down axon
-

Question 4

Axon

Answer 4

branch coming off the cell body, propagates action potential

Question 5

Axon Terminals

Answer 5

release neurotransmitter on arrival of an action potential (pass information)

Question 6

Excitatory Neurostrasmitters

Answer 6

• open ligand-gated channels to allow sodium in to depolarize neuron
• depolarization heads towards hillock through the grated potential

Question 7

Action Potential Generation

Answer 7

• elicited at axon hillock and propagated along the axon

What if voltage-gated sodium channels were blocked?
- no propagation occuring
- toxin would block voltage gated sodium channels prevent propagation

Question 8

Exocytosis

Answer 8

• voltage-gated calcium channels open in the button
• calcium triggers exocytosis of excitatory neurotransmitters
  (1) a nerve impulse initiates voltage-gated calcium channels to open up
  (2) calcium triggers exocytosis driving neurotransmitters into synaptic cleft
  (3) if a neuron generates more action potentials over a short period of time there is an increase in calcium entry into axon terminal, and thus, more neurotransmitters are released

Question 9

Spatial Summation

Answer 9

• multiple neurons working together so that a high enough frequency (number per second) of action potentials can be generated to get the postsynaptic neurons to threshold

Question 10

Inhibitory Neurotransmitters

Answer 10

• many different types
• hyperpolarize (make more negative) neurons which make generating an action potential harder
  
  • “inhibit” them

Question 11

Epimysium

Answer 11

surrounds the whole muscle
Epi = outside

Question 12

Perimysium

Answer 12

surrounds a fascicle
Peri = surrounding/around

Question 13

Endomysium

Answer 13

surrounds a muscle fiber
Endo = within

Question 14

Myofibirl

Answer 14

contractile organelle that runs the length of the myocyte
- made of repeating segments called sarcomeres
- coming off z-disc is thin filament actin
- coming off m-line is thick filament myosin

Question 15

Sliding Filament

Answer 15

how myosin and actin interact
- calcium and ATP allow for interaction
- head will continue cycling, pulling actin towards m-line
- sarcomeres will shorten –> myofibrils will shorten –> muscel fibers will shorten –> muscle will shorten (contraction)
- crossbridging
- pul together to build cross bridge
- more cells = more crossbridging

Question 16

Neuromuscular Junction

Answer 16

• exocytosis occurs in the axon terminal
• neurotransmitters go into synaptic cleft
• sarcolemma have ACh receptors
• End Plate potential: how much acetylcholine (ACh) is available

Question 17

Motor Unit

Answer 17

• motor unit with more attachments has greater potential to generate more force
• work in conjunction “recruitment”
  
  • overall greater force output

Question 18

The Size Principle

Answer 18

smaller particles are recruited first, as time increases, bigger motor units get recruited

Question 19

Electromyographic

Answer 19

recording electrical activity to identify muscle potential

Question 20

EMG Data

Answer 20

Method:
Intermuscular: needle is used to stimulate muscle
- more invasive
- validity is increased
Surface: leads read muscle stimulation

Graph:
Raw: scribbled lines
Intergrated: easier to see trends, more meaningful

Question 21

Maximal Volitional Contraction (MCV)

Answer 21

the maximal force-generating capacity of a muscle or group of muscles in humans