Lecture 6 - Muscles pt. 2 Flashcards
What are wave summations?
they are when a stimulus occurs before the muscle relaxes completely
What is tetanus?
Tetanus occurs when a high stimulus frequency occurs with no relaxation at all
What are the two types of tetanus and what do they look like?
-unfused = wavelike
-fused = like a platform
What is an important feature of stimulus and contraction?
even with an increase in stimulus there is a maximum contraction
What are the 2 graded muscle responses?
-wave summation (change frequency of stimulation)
-motor unit summation (change the # of motor units activated)
1 motor unit is compromised of what?
1 motor neuron + all muscle fibres it supplies
What is the name of the enzyme that breaks down Ach?
acetylcholinesterase
What is muscle tone?
a relaxed muscle is still contracted which creates tone
What is an eccentric contraction?
the motion of a active muscle lengthening under a load
What is a concentric contraction?
the motion of an active muscle shortening under a load
What kind of energy supply is needed for fast sports? (weights, diving, sprinting)
ADP + CP
What kind of energy supply is needed for medium-length sports? (soccer, tennis, 100m swim)
anaerobic
What kind of energy supply is needed for long-lasting sports? (marathon, jogging)
aerobic
When does muscle fatigue occur?
-ATP shortage
-the build-up of lactic acid
-ion imbalances
How to counter oxygen dept which occurs post exercise?
-convert lactic acid + pyruvic acid
-glycogen
-ATP + CP
-Cori cycle
What is the heat production of the muscle?
ATP-driven muscle contractions with 20-25% efficiency
What are the 3 muscle fibre types?
=name (colour) - Type __
-what made of?
-where?
-fatigue?
-power?
=slow oxidative fibres (red) - Type 1
-slow-acting myosin ATPases
-capillaries + aerobic enzymes
-fatigue resistant
-no power
=fast glycolytic fibres (white) - Type 2 B
-fast-acting myosin ATPases
-few mitochondria, glycogen storage
-fatigues
-powerful
=fast oxidative fibres (pink) - Type 2 A
-fast-acting myosin ATPases
-fast contractions + aerobic + glycogen
-a little fatigue resistant
-medium power
What does smooth muscle look like?
-small, spindle-shaped cells
-1 central nucleus
- sarcoplasmic reticulum
-no t-tubule
-no striations
What do varicosities do?
release neurotransmitters into wide synaptic clef
Thick vs thin filaments in smooth muscle
-ration…
-tropomyosin…
-sarcomeres…
-make up…
-1:13 thick to thin
-tropomyosin + calmodulin
-no sarcomeres
-non-contractile intermediate filaments + dense bodies
Thick vs thin filaments in skeletal muscle
-ratio…
-tropomyosin
-sarcomeres
-makeup
-1:2 thick to thin
-tropomysosin + troponin
-sarcomeres from z-disk to z-disk
-lots of stuff
How does contraction happen in smooth muscle?
-electrical coupling via gap junctions and synchronized contractions
1) actin + myosin interact
2) Ca2+
3) sliding process by ATP
4 special features of smooth muscle contractions?
=name
-explanation
=response to stretch
- more stretch = more contraction
=length + tension changes
-better than skeletal
=hyperplasia
=secretory functions
-collagen + elastin make own CF
Single-unit smooth muscle
-where
-other info
-visceral/most common
-contracts as unit
-gap junctions
-spontaneous AP
-all other SM characteristics
Multi-unit smooth muscle
-where
-other info
-airways, arteries, hair, eyes
-no synchronization
-gap junctions
-neural stimuli by graded potentials
-structurally independent
-many nerve endings
