Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

KP222 > Quiz #4 > Flashcards

Quiz #4 Flashcards

1
Q

What is a muscle twitch?

A

a single contraction-relaxation cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the phases of a muscle twitch.

A

latent period
- time before Ca2+ has bound to troponin

contraction phase

  • muscle tension increases to a maximum value
  • crossbridge interactions

relaxation phase
- tension decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are series elastic elements?

A

connective tissue, tendons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is an isometric muscle contraction?

A

length remains constant

contractile elements contract and create tension

load is greater than tension, stretches series elastic elements

only sarcomeres shorten, muscle does not shorten, load not lifted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 2 types of forces in muscle contraction?

A

tension - force exerted by contracting muscle

load - force opposing contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an isotonic muscle contraction?

A

constant tension

when tension is greater than load

  • concentric contraction
  • muscle shortens, load is lifted

when load is greater than tension

  • eccentric contraction
  • muscle lengthens, weight is lowered
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a motor unit?

A

a motor neuron and all the fibers it innervates

of muscle fibers in unit varies according to degree of fine control capability of muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the innervation ratio?

A

motor neurons:muscle fibers

ex. gastrocnemius has about 2000 fibers/MU
- gross movement

extraocular has about 3-5 fibers/MU
- fine movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the muscle fiber types?

A

slow twitch (I)

  • fatigue resistant
  • lower force/power

fast twitch (IIA)

  • more fatigue resistant than IIB but less than I
  • intermediate force/power

fast fibers (IIB)

  • powerful
  • easily fatigued
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What makes muscle contractions vary?

A

type of active motor units

of active motor units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 2 types of twitch summation?

A

temporal

  • frequency of MU activation
  • more forceful contraction

spatial

  • # of MU recruited
  • sustained tension less than maximal, lets MU to rest in rotation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens if time between APs is too long?

A

complete recovery in between

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is unfused/incomplete tetanus?

A

stimuli far enough apart to allow slight relaxation

fiber not firing at max rate

wavy curve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is complete tetanus?

A

muscle never beings to relax inbetween stimuli since there is no time

continuous contraction and steady tension at maximum force

at fatigue, tension decreases rapidly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does resting fibre length affect muscle twitch?

A

twitch force depends on length of individual sarcomeres before contraction

optimal overlap of filaments = optimal force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the sliding filament theory?

A

tension that a muscle fiber generates is directly proportional to the number of crossbridges formed between filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the principle of asynchronous recruitment.

A

MUs take turns firing/relaxing so they have time to rest and can consistently maintain uniform tension across a muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How can motor unit sizes vary?

A

size of unit
- small for delicate movements, large for strength movements

fiber diameter
- small for weaker movements, large for stronger movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the size principle?

A

the order of motor unit recruitment is related to their size

small units recruited before large units

larger neurons are more difficult to depolarize, they require more excitatory input to reach threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the relationship between load and velocity of shortening?

A

inverse relationship

for a muscle to shorten, it must generate force greater than the load

when load is greater than maximum tension, velocity of shortening is zero because the load cannot be lifted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What differs in the contraction of fast and slow twitch muscle fibers?

A

fast fibers contract and relax 2-3x faster than slow fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are muscle spindles? What are the fibers that compose it?

A

detect changes in length

intrafusal fibers

  • contractile cells of spindle
  • innervated by gamma (slow) MU
  • adjust sensitivity of muscle to stretch

extrafusal fibers

  • contractile cells of muscle
  • responsible for contraction
  • innervated by alpha (fast) MU
23
Q

What are golgi tendon organs?

A

detect changes in tension

inhibits muscle to protect against overactivity

sensory neurons from GTOs synapse on interneurons that make inhibitory synapses on motor neurons to prevent excessive contraction

24
Q

What would happen to muscle if gamma neurons did not fire?

A

alpha MU would fire, muscle contracts but intrafusal fibers dont, less stretch experienced on centres, decreases firing rate of afferent neurons

25
Q

What is reciprocal inhibition?

A

in a monosynaptic reflex, neuron synapses with antagonist muscle to inhibit activity at the same time as it activates the agonist

allows for reflex to occur

26
Q

Where are some of the locations smooth muscle exists in?

A 
vessels
gastrointestinal tract
urinary tract
respiratory tract
reproductive organs
ocular muscles
27
Q

What are some differences smooth muscle contraction has compared to skeletal muscle?

A 
can sustain contractions for longer periods of time
filaments run oblique not parallel
contractile fibers not in sarcomeres
controlled by ANS
Ca2+ comes from both ECF and SR
Ca2+ does not bind to troponin
28
Q

Describe smooth muscle contraction cycle.

A 
voltage-gated Ca2+ channels in plasma membrane open
Ca2+ triggers release of Ca2+ from SR
Ca2+ binds to calmodulin
Ca2+-calmodulin activates MLCK
MLCK phosphorylates myosin
crossbridge cycling occurs

relaxation:
phosphotase removes phosphate from myosin
Ca2+ removed from cytoplasm by Ca2+-ATPase and Ca2+-Na countertransport

29
Q

Describe the neural regulation of smooth muscle.

A

innervated by ANS
- both SNS and PNS

may be excitatory or inhibitory

NT released from varicosities

30
Q

What are the 3 main components of the cardiovascular system?

A

the heart
blood vessels
blood

31
Q

What are the 2 circuits of blood flow through the heart?

A

right = pulmonary circuit = to lungs and back for gas exchange

left side = systemic circuit = to all of the tissues of the body and back for off-loading of oxygenated blood

32
Q

What is the pericardium?

A

membranous sac surrounding the entire heart

lubricates the heart to decrease friction

33
Q

What are the true definition of arteries and veins?

A 
arteries = vessels that travel away from the heart
veins = vessels that travel to the heart
34
Q

What is the SA node?

A

natural pacemaker of the heart

35
Q

What are the layers of tissue of the heart?

A

epicardium
- outer layer covering the heart for protection

myocardium

  • middle muscular wall of the heart
  • contractile, concentric layers of muscle tissue

endocardium
- inner layer protecting valves and heart chambers

36
Q

Which ventricle is thicker and why?

A

left because it has to push a stronger force of contraction to push blood to the entire body not just the lungs

37
Q

What drives the blood flow through the heart?

A

pressure in different chambers

38
Q

What are atrioventricular valves?

A

separate atria and ventricles
right side: tricuspid
left side: bicuspid/mitral

39
Q

What are chordae tendinae?

A

attach to papillary muscles on muscular wall of ventricles, keep a level of tension between AV valve and papillary muscles to ensure valves close when ventricles contract

prevents backflow

40
Q

What are semilunar valves?

A

between left ventricle and aorta (aortic valve) and right ventricle and pulmonary veins (pulmonary valve)

open with ventricular contraction, remaining blood pushes valve shut during relaxation to prevent backflow

41
Q

What are the 2 types of myocardial cells?

A

contractile
- 99% of cells

autorhythmic
- can generate AP spontaneously
- pacemaker cells
initiates APs and establishes heart rate
- conduction fibers
transmits/spreads generated APs
42
Q

What are some similarities of cardiac muscle to skeletal muscle?

A

striations

sarcomeres

43
Q

What are some differences of cardiac muscle to skeletal muscle?

A

less SR, no terminal cisternae
under ANS control
intercalated discs to connect cells
single nucleus

44
Q

What are the 2 components of intercalated discs that connect cells together?

A

gap junctions
- direct electrical connection of adjacent cells to make them a functional unit

desmosomes

  • “glue” that holds cells together
  • proteins binding adjacent cells to allow for chemical communicatoin
45
Q

What are the pacemaker cells of the myocardium?

A

SA node
- where APs originate

AV node
- slower, but still capable of generating APs

46
Q

What are the conduction fibers of the myocardium?

A

internodal pathways
bundle of His
Purkinje fibers

47
Q

Describe the initiation and conduction pathway of an impulse through the heart.

A

AP initiated in SA node, travels through atria
AV node, conduction slows (delay)
bundle of His
splits into left and right bundle brances
Purkinje fibers
travels back upwards through ventricles
heart eventually returns to rest until SA node regenerates

48
Q

What cells have the highest firing rates at rest?

A

SA node

fastest depolarizing cells set the rate for the rest of the heart (pacemaker)

49
Q

What is an ECG?

A

composite of all APs generated by nodal and contractile cells

50
Q

What are the components or a normal ECG wave?

A

P wave
- atrial depolarization, initiated by SA node

delay at AV node

QRS complex

  • ventricular depolarization
  • and atrial repolarization but this is covered up by QRS

T wave
- ventricular repolarization

51
Q

What are T-type and L-type channels?

A

T = transient, slow depolarization

L = long-lasting, rapid depolarization

52
Q

What are funny channels and their role?

A

open up right after repolarization (unlike other ionic channels), lead to Na+ flow in making it less negative

at -55mV, Ca2+ channels open and funny channels close

T-type channels open

at -50mV, L-type channels open and Ca2+ rushes in causing full depolarization and action potential

K+ channels start opening, exiting the ICF and making it more negative until it is at -70mV again (resting state) and funny channels reopen

never a resting phase

53
Q

What are the 5 phases of ionic activity in the hearT?

A

phase 0

  • membrane depolarizes
  • Na+ channels open

phase 1 - depolarization

  • open Na+ channels start to close
  • drop in membrane potential
  • but Ca2+ channels start to open and K+ channels start to close, results in only small drop

phase 2 - plateau

  • most K+ channels closed, most Ca2+ channels open
  • keeps membrane depolarized

phase 3 - repolarization

  • opening K+ channels take effect, make cell more negative
  • Ca2+ channels close

phase 4 - rest

54
Q

What things are not possible in myocardial cell activation that are in skeletal cell activation?

A

twitch summation and tetanus

due to long absolute refractory period

KP222 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions