Brainscape's Knowledge GenomeTM

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


See full index

Cells to systems > Lecture 19 > Flashcards

Lecture 19 Flashcards

1
Q

What is summation of twitches

A
  • Process by which individual twitches combine
  • Produces sustained contractions
  • Can lead to tetanic contractions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does Recruitment of Motor Units mean

A
  • increase in the number of motor units activated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What can recruitment do

A

• Whole muscle composed of many motor units
• More precise movements are produced with fewer muscle
fibers within a motor unit
• As intensity of stimulation increases, recruitment of motor units
continues until all motor units are activated

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

What muscles are recruited first followed by which

A
  1. Motor unit one :slow-oxidative fibers
  2. Motor unit 2 : fast-oxidative fiber
    3: Motor unit three : fast-glycolytic fibers
  • Smaller motor units (smaller diameter axons) - recruited first
  • Larger motor units (larger diameter axons) - recruited later
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is muscle tone

A

continuous state of partial contraction

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

What is going on during • Slow-twitch fibers (Type I)

A
  • Always oxidative
  • Resistant to fatigue
  • Red fibers
  • Most myoglobin
  • Good blood supply
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Fast-twitch fatigue-resistant

fibers (Type IIa)

A 
• Intermediate fibers
• Oxidative
• Intermediate amount of
myoglobin
• Pink to red in color
• Resistant to fatigue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is • Fast-twitch glycolytic fibers (Type IIb)

A
  • White fibers (less myoglobin)
  • Poorer blood supply
  • Susceptible to fatigue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference between the cardiace muscle and skeletal muscle for how it works

A

• Differences in cardiac muscles

  • Not initiated by neuronal input
  • All cells are electrically coupled
  • Long action potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the general structure of cardiac muscle

A 
• Uni-nucleate cell
• Z lines, M lines, A
bands, I bands
• Relatively short
• Branching and
interdigitate
• Arranged in series and
parallel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where are the location of intercalated disk in cardiac muscles

A 
• 2 regions
• Transverse portion,
aligned with Z line,
desmosomes,
mechanical cohesion
• Lateral portion, parallel
to myofilaments, rich in
gap junctions, low
resistance pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the three types of heart muscle cells

A
  1. Cells of myocardium
  2. Rhythmically active self
    excitatory “pacemaker”
    cells
  3. Purkinje fibres,
    specialised conducting
    pathways which
    enhance spread of
    localised excitation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does cardiac receive signal

A 
• AP spreads along
plasma membrane and
invades T tubules
• This opens voltage
sensitive Ca++ channels
in T-tubule membrane
• Diffusion of extracellular calcium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How Excitation contraction coupling work in cardiac muscle

A
  1. Excitation/depolarization
  2. opening of voltage-sensitive plasma membrane C2+ channels
  3. Flow of Ca2+ into cell
  4. Stimulation of Ca2+, release from sarcoplasmic reticulum
  5. increase cytosolic Ca2+ concentration
  6. contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the extracellular Ca2+ do

A

Extracellular Ca++
stimulates release of Ca++
from SR

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

What is the contraction of the cardiac muscle called

A

systole

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

What does the strength of contraction depend on

A

dependent on presence
and concentration of
extracellular Ca++

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

What is the contractility influence by

A 
• Ca++ levels
• Hormones (epinephrine)
• Nervous (autonomic)
• Extent of stretch
• Cardiac muscle operates in a range of lengths shorter
than optimal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is contraction of smooth muscle mediated by

A

Contraction mediated by actin and myosin

cross-bridge cycling

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

Is smooth muscle sarcomere obvious

A

Undefined sarcomere struct

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

What are the smooth muscle bound together by

A

basement

membrane and transmits force

22
Q

Do smoother muscle have T-tubules

A

no, • Small membrane invaginations called caveoli

• SR if rudimentary

23
Q

what is the dense body attached to

A

actin filament and membrane

24
Q

What are the dense bodies linked by

A

Linked by diagonal
network of
intermediate filaments
(desmin)

25
Q

Is there troponin present in smooth muscle

A

no

26
Q

Is there myosin heads in smooth muscle

A

yes

27
Q

are smooth muscle connected together

A

no, they are individual cells

28
Q

What are in between Multi-unit smooth muscles

A

autonomic neuron varicosity

29
Q

Is smooth muscle responsive to stretch

A

no

30
Q

Is smooth muscle responsive to hormones

A

Minimal response to

hormones

31
Q

What are the connect the smooth muscle in single-unit smooth muscle

A

linked electricall by gap junction

32
Q

where are the autonomic neuron varicosity in single-unit smooth muscle

A

on the outside

33
Q

What is a single-unit smooth muscle

A 
• Network of closely
opposed cells acting as a
single unit
• Direct stimulation of only
a few
34
Q

What is desmosomes

A

a structure by which two adjacent cells are attached, formed from protein plaques in the cell membranes linked by filaments.

35
Q

How many adherence

points (desmosomes) are there in single-unit smooth muscle

A

multiple

36
Q

What does Single-Unit Smooth Muscle respond to

A 
• Neural signals
• Hormones
• Mechanical stretch
• Local “pacemaker”
potentials
37
Q

Where are Single-Unit Smooth Muscle used

A

• Muscles of uterus,
intestinal tract, bile
duct, small blood
vessels

38
Q

What are 3 types of innervation

A

• Extrinsic: both sympathetic and parasympathetic
• Intrinsic: short neurons forming plexuses (networks)
with tissue
• Afferent sensory: autonomic reflexes

39
Q

What are the branching of fibres from in smooth muscle fibre

A

postganglionic sympathetic neuron

40
Q

What does the fibres of postganglionic sympathetic neuron have

A

Branching of fibres with
“varicosities” that contains
vesicles with neurotransmitter
(both acetylcholine and norepinephrine)

41
Q

How are the innvervation of muscle cells placed

A

• Modulatory rather than

inducing

42
Q

What inputs does the postganglionic sympathetic neuron give

A

Potential for both sympathetic

and parasympathetic input

43
Q

How does Non- neural activation work

A

• Hormones can open and/or close ion channels
changing membrane potential
• Chemical stimuli can cause release of Ca++ from SR
without a change in membrane potential
• Other influences
• Decreased oxygen, pH, body temperature

44
Q

What is the regulation of contraction in smooth muscle compared to skeletal muscle

A

• Ca++ regulates cross bridge formation and
thus cycling
• BUT different from skeletal muscle
• Control of Ca++ levels
• Influence on cross bridge formation (myosin)

45
Q

How are the cytosolic Ca2+ controlled in order to supply Ca2+ to smooth muscle

A
  • receptor mechanisms like neurotransmitter or hormone
  • Membrane potential-dependent channels
  • Ca2+ released from sarcoplasmic reticulum upon receptor activation
  • Ca2+ removed
46
Q

What is smooth muscle cross bridge controlled by

A

Cross bridge binding
modulated by
Ca++ dependent
phosphorylation of myosin

47
Q

What are the steps for relationship between crossbridge and Ca2+in smooth muscle

A
  1. increase in cytosolic Ca2+
  2. Ca2+ binds to calmodulin in cytosol
  3. Ca2+ - calmodulin complex binds to myosin
  4. Myosin light-chain kinases uses ATP to phosphorylate myosin cross bridges
  5. Phosphorylated cross bridge bind to actin filaments
  6. Cross-bridge cycle produces tension and shortening
48
Q

When can strength be exerted optimally

A

in an optimal length

49
Q

What does tetanic contraction mean

A

maintaining the contraction

50
Q

Where does the calcium from cardiac muscle come from

A

diffusion of extracellular calcium, not SR

Cells to systems (25 decks)

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