Lecture 6 - Muscles pt. 2

Question 1

What are wave summations?

Answer 1

they are when a stimulus occurs before the muscle relaxes completely

Question 2

What is tetanus?

Answer 2

Tetanus occurs when a high stimulus frequency occurs with no relaxation at all

Question 3

What are the two types of tetanus and what do they look like?

Answer 3

-unfused = wavelike
-fused = like a platform

Question 4

What is an important feature of stimulus and contraction?

Answer 4

even with an increase in stimulus there is a maximum contraction

Question 5

What are the 2 graded muscle responses?

Answer 5

-wave summation (change frequency of stimulation)
-motor unit summation (change the # of motor units activated)

Question 6

1 motor unit is compromised of what?

Answer 6

1 motor neuron + all muscle fibres it supplies

Question 7

What is the name of the enzyme that breaks down Ach?

Answer 7

acetylcholinesterase

Question 8

What is muscle tone?

Answer 8

a relaxed muscle is still contracted which creates tone

Question 9

What is an eccentric contraction?

Answer 9

the motion of a active muscle lengthening under a load

Question 10

What is a concentric contraction?

Answer 10

the motion of an active muscle shortening under a load

Question 11

What kind of energy supply is needed for fast sports? (weights, diving, sprinting)

Answer 11

ADP + CP

Question 12

What kind of energy supply is needed for medium-length sports? (soccer, tennis, 100m swim)

Answer 12

anaerobic

Question 13

What kind of energy supply is needed for long-lasting sports? (marathon, jogging)

Answer 13

aerobic

Question 14

When does muscle fatigue occur?

Answer 14

-ATP shortage
-the build-up of lactic acid
-ion imbalances

Question 15

How to counter oxygen dept which occurs post exercise?

Answer 15

-convert lactic acid + pyruvic acid
-glycogen
-ATP + CP
-Cori cycle

Question 16

What is the heat production of the muscle?

Answer 16

ATP-driven muscle contractions with 20-25% efficiency

Question 17

What are the 3 muscle fibre types?
=name (colour) - Type __
-what made of?
-where?
-fatigue?
-power?

Answer 17

=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

Question 18

What does smooth muscle look like?

Answer 18

-small, spindle-shaped cells
-1 central nucleus
- sarcoplasmic reticulum
-no t-tubule
-no striations

Question 19

What do varicosities do?

Answer 19

release neurotransmitters into wide synaptic clef

Question 20

Thick vs thin filaments in smooth muscle
-ration…
-tropomyosin…
-sarcomeres…
-make up…

Answer 20

-1:13 thick to thin
-tropomyosin + calmodulin
-no sarcomeres
-non-contractile intermediate filaments + dense bodies

Question 21

Thick vs thin filaments in skeletal muscle
-ratio…
-tropomyosin
-sarcomeres
-makeup

Answer 21

-1:2 thick to thin
-tropomysosin + troponin
-sarcomeres from z-disk to z-disk
-lots of stuff

Question 22

How does contraction happen in smooth muscle?

Answer 22

-electrical coupling via gap junctions and synchronized contractions
1) actin + myosin interact
2) Ca2+
3) sliding process by ATP

Question 23

4 special features of smooth muscle contractions?
=name
-explanation

Answer 23

=response to stretch
- more stretch = more contraction

=length + tension changes
-better than skeletal

=hyperplasia

=secretory functions
-collagen + elastin make own CF

Question 24

Single-unit smooth muscle
-where
-other info

Answer 24

-visceral/most common
-contracts as unit
-gap junctions
-spontaneous AP
-all other SM characteristics

Question 25

Multi-unit smooth muscle
-where
-other info

Answer 25

-airways, arteries, hair, eyes
-no synchronization
-gap junctions
-neural stimuli by graded potentials
-structurally independent
-many nerve endings