Brainscape's Knowledge GenomeTM

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


See full index

Module 204: Musculoskeletal system > Physiology of muscles > Flashcards

Physiology of muscles Flashcards

1
Q

Sarcomere structure

  • Z line
  • I band
  • A band
  • H zone
  • M line
A

Sarcomere= the region between 2 Z lines

Z band
- In the middle of I band. Anchors actin filaments and is connected to myosin via titin.

I band (Light band)
- Consists of actin filaments only
A band (Dark band)
- Consists of actin and myosin filaments

H zone
- Zone in the middle of sarcomere, composed of only myosin

M line
- Middle of H zone

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

Myofibril

A

Myocyte. Protein filaments composed of:

  • Actin
  • Myosin
  • Titin

And others

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

Myofilaments

A

Components of myofibrils. Primary actin and myosin

Myofilaments repeat in myofibrils to form sarcomeres.

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

Force generation in sarcomere

A

Optimal sarcomere length is required for greatest force generation during a power stroke.

When the sarcomere is too short
- Actin filaments collide, low force generated

When the sarcomere is too long
- Actin and myosin cannot bind effectively enough= low force

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

Cross bridge cyclin

A
  1. Myosin releases actin: Occurs when ATP binds to myosin head.
  2. Myosin head cleaves ATP= ADP+ Pi made. This cocks myosin head.
  3. Myosin head binds to actin in the presence of Ca2+
    - 4Ca2+ binds to Troponin C to move tropomyosin from actin binding site.
  4. Power stroke= Release ADP + Pi.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Creatine phosphate

A

Energy storage in muscles

- Source of Pi for ATP synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Creatine kinase/ phosphokinase (CK, CPK)

  • Mechanism
  • Diagnosis
A

Catalyses the conversion of creatine to creatine phosphate (and vice versa).

Mitochondrial CK= produces Creatine phosphate

Myofibrillar CK= produces ATP (release Pi from creatine phosphate)

Diagnosis
- When elevated= marker for muscle destruction.

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

Troponin C

A

Section of troponin where Ca2+ binds to. (4Ca in muscle, 3Ca in heart)
- Causes confirmational change which moves tropomyosin

Movement of tropomyosin reveals binding site for myosin to bind to actin

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

Markers for muscle breakdown

A

Total Troponin I (TNI)

Cardiac TNI = MI marker

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

Ryanodine receptors

A

Located in the plasma membrane of myocyte’s sarcoplasmic reticulum.

Allows efflux of calcium after stimulation from depolarisation via T tubules.

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

SERCA channel

A

Located in the membrane ER in myocytes.

Sequestrates Ca2+ back into ER, using ATP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Rigor mortis mechanism

A

3rd stage of death that occurs a couple hours after death.

Due to no more ATP produced:
- Myosin cannot release actin, as it requires ATP.
- SERCA cannot sequester Ca2+ back into ER
= Causes constant contraction of sarcomere, stiffens limbs

Wears off a few days later when muscles starts to degenerate.

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

Tetany

A

Summation of contraction,- As a result of continuous stimulation from APs
- Muscle is unable to relax due to insufficient Ca2+ sequestration.

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

Slow twitch fibres

  • Colour
  • Oxygen
  • Size
  • Fibre type
  • Other features
A

Red, oxidative, small fibres (in diameter)

Type 1, slow twitch

Contains high numbers of myoglobin and mitochondria

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

Fast twitch fibres

  • Colour
  • Oxygen
  • Size
  • Fibre type
  • Other features
A

White, non-oxidative, large fibres
- Main source of energy is from glycolysis

Type 2

Lower levels of myoglobin

Use= fast, precise movements (i.e eye and hand muscles.)

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

Compare slow and fast twitch fibres:

  • Respiration
  • Calcium reuptake speed
  • Tension produced
  • Fatigue resistance
A

Respiration

  • Slow= aerobic
  • Fast= anaerobic

Calcium reuptake speed
- Fast twitch do it much faster than slow twitch

Tension produced
- Fast= maximum tension, slow= lower tension

Fatigue resistance
- Fast= lower than slow fibres.

17
Q

Soleus muscle fibres

A

Mainly slow fibres as it is a postural muscle (walking)

  • 80% type 1
  • 20% type 2a
18
Q

Vastus lateralis fibres

A

Quadriceps muscle:

- Mixture of Type 1, 2a, 2x

19
Q

Motor unit

A

A single alpha motor neuron and the muscle fibres it innervates
- All the same type of fibres.

20
Q

Isometric contraction

A

Variable change in force generation whilst muscle length is unchanged
- Joint angle remains the same

Generates enough force to overcome resistance before isotonic contraction

21
Q

Isometric contraction example

A

Initiate stage of picking up a glass
- Biceps and brachiradialis generate force enough to eventually move the forearm at elbow.

As contraction occurs, more motor units are recruited (recruitment)
- The recruited fibres are progressively larger

22
Q

Isotonic contraction

A

Change in muscle length as constant force is generated.

Joint angle is changed

Example
- Bringing the glass of water to mouth. Force generated must be constant unless it would smash you in the face

23
Q

Concentric contraction

A

Force during contraction

- i.e taking off in long jump

24
Q

Eccentric contraction

A

Force during muscle elongation

- i.e landing in long jump

25
Q

Stretch reflex

A

Function: for posture and balance

Sensory organ: Intrafusal spindle fibres, changes length of muscle according to stretch.

Example: Patellar reflex

26
Q

Patella reflex

A

A type of stretch reflex

  • Monosynaptic
  • Ipisilateral
  • Spinal
27
Q

Gamma motor neurone

A

A lower motor neurone

  • Adjusts sensitivity of muscle spindles
  • Keeps the spindles taut.
28
Q

Tendon reflex

A

Function: Protects from overloading of muscle by decreasing force generated.

Sensory organ: Golgi tendon organ
- In series with muscle fibres, detects tension in muscle.

Example: Golgi tendon reflex

29
Q

Golgi tendon reflex

A

Changes the force generated in muscle, when there is overloading.

  • Ipisilateral
  • Disynaptic
  • Spinal

Golgi tendon detects change in tension for muscle= stimulates inhibitory neurone
- Motor neurone is inhibited= less contraction of muscle

30
Q

Westphal sign

A

Absent/ Decreased Knee jerk reflex

Causes:

  • Receptor damage
  • Femoral nerve damage
  • Peripheral nerve disease

Module 204: Musculoskeletal system (22 decks)

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