Brainscape's Knowledge GenomeTM

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


See full index

Anatomy and Physiology > Muscle Tissue Lecture 3 > Flashcards

Muscle Tissue Lecture 3 Flashcards

1
Q

NMJ Definition

A
  • Area where somatic motor neuron terminal and skeletal muscle synapse/connect.
  • Site for transmitting action potential from nerve to muscle.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Ca2+ Influx and AP

A
  • Ca2+ influx into muscle fiber due to AP.
  • AP causes membrane changes, opening/closing ion channels, releasing Ca2+.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Somatic Motor Neurons

A
  • Extend from brain & spinal cord, responsible for somatic movements.
  • Terminate at muscle fiber sarcolemma, forming NMJ.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Synaptic Cleft

A
  • Gap between somatic neuron terminal and muscle.
  • Allows communication between nerves.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Neurotransmitters

A
  • NTs propagate signals across cleft.
  • Excitatory/inhibitory effects depending on synapse.
  • Acetylcholine (ACh) is primary neurotransmitter at NMJ.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

ACh and Motor End Plate

A
  • ACh stored in vesicles in pre-synaptic terminal.
  • Motor end plate: Post-synaptic membrane with ACh receptors.
  • ACh binding triggers ion channel opening.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Presynaptic vs. Postsynaptic

A
  • Presynaptic membrane: Motor neuron terminal.
  • Postsynaptic membrane: Muscle fiber (motor endplate).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Steps of AP Generation:

A
  1. Release of ACh
  2. Activation of ACh receptors
  3. Production of the Action Potential
  4. Termination of the Action Potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Release of ACh

A
  • Nervous impulse reaches axon terminal.
  • Voltage-gated Ca2+ channels open.
  • Ca2+ triggers exocytosis of ACh into cleft.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Activation of ACh Receptors

A
  • ACh binds to ligand-gated Na+ channels at motor endplate.
  • Opens channels, allowing Na+ influx into sarcoplasm.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Production of Action Potential

A
  • Na+ influx causes cell depolarization.
  • Opens more voltage-gated Na+ channels, generating AP.
  • AP propagates along sarcolemma, triggering Ca2+ release from SR for muscle contraction.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Termination of Action Potential

A
  • ACh must be removed once nerve signal stops.
  • ACh removed by diffusion or broken down by acetylcholinesterase (AChE).
  • End products recycled for new ACh synthesis.
  • Some NTs removed via reuptake, but not ACh.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Characteristics of Cardiac Muscle

A
  • Heart is hardest working muscle.
  • Beats over 100,000 times daily.
  • Average 75 beats per minute.
  • Striated and involuntary.
  • Uses Ca2+ ions from SR and interstitial fluid.
  • Allows prolonged contraction (10-15x longer than skeletal muscle).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Auto-Rhythmicity of Cardiac Muscle

A
  • Contracts in response to self-generated action potentials.
  • Does not rely on nerve supply.
  • Some cells are “self-excitable” (pacemaker cells).
  • Generate rhythmic contractions to adjacent cells.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Pacemaker Cells

A
  • Sinoatrial (SA) node
  • Atrioventricular (AV) node
  • Responsible for automatic rhythmic contractions of upper and lower heart portions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Characteristics of Smooth Muscle

A
  • Non-striated and involuntary.
  • Can be autorhythmic, influenced by nervous system.
  • Action potential in one fiber spreads to neighboring fibers, causing synchronized contraction.
16
Q

Structural Features of Smooth Muscle

A
  • Thin filaments attached to dense bodies (similar to Z-discs).
  • Intermediate filaments also attach to dense bodies, transmitting tension from muscle contraction.
17
Q

Caveolae in Smooth Muscle

A
  • Pouchlike invaginations containing extracellular Ca2+.
  • Less sarcoplasmic reticulum (SR) and no transverse tubules.
  • Contraction relies more on extracellular calcium.
18
Q

Role of Calmodulin

A
  • Protein binding to Ca2+ in smooth muscle.
  • Acts as regulatory protein like troponin in skeletal muscle.
  • Activates myosin heads for contraction.
  • Contraction involves pulling of actin and myosin on dense bodies, intermediate fibers, causing cell contraction.
19
Q

Biological Energy Systems:

A

Anaerobic Processes:
* Occur without oxygen.
* Short bursts of high-intensity movements.

Aerobic Processes:
* Require oxygen.
* Long-duration, low-intensity exercises.

20
Q

Types of Exercises

A

Anaerobic:
* Weight training, sprinting, interval training.

Aerobic:
* Running, walking, swimming, biking.

21
Q

Anaerobic Glycolysis

A
  • Breaks down glucose to yield ATP.
  • Produces lactic acid in absence of oxygen.
  • Provides ATP for moderate to high-intensity, short-term exercise.
22
Q

Aerobic Respiration

A
  • Occurs in presence of oxygen.
  • Utilizes pyruvic acid from glycolysis to produce ATP.
  • Primary source of ATP at rest and during low-intensity activities.
23
Q

Muscle Fatigue

A
  • Inability to maintain forceful contraction.
  • Reasons include lack of oxygen, calcium, ATP, or buildup of waste products.
24
Q

Oxygen Replenishment

A
  • Postexercise oxygen uptake termed Oxygen Debt or EPOC.
  • Used for resynthesis of ATP and creatine phosphate, glycogen, and tissue oxygenation.
25
Q

Motor Unit

A
  • Includes somatic motor neuron & all innervated muscle fibers.
  • Can range from 1 fiber per neuron to over 3000 fibers per neuron.
26
Q

Muscle Twitch

A
  • Brief contraction of all fibers in response to a single action potential (AP).
  • Lasts about 20-200 msec, longer than muscle AP.
27
Q

Fasciculations

A
  • Involuntary visible contractions of motor units.
  • Can be benign or indicative of underlying pathologies.
28
Q

Stages of Contraction

A

Latent Period: AP sweeps sarcolemma, no tension.
Contraction Period: Ca²⁺ binds, crossbridges form, contraction.
Relaxation Period: Crossbridges break, Ca²⁺ restored.
Refractory Period: Subsequent AP can’t generate contraction.

29
Q

Frequency of Stimulation

A
  • Peak tension depends on stimulation frequency.
  • Myograms show effects like wave summation, unfused tetanus, fused tetanus.
30
Q

Un-Fused Tetanus

A
  • Sustained, wavering contraction at 20-30 stimuli/sec.
  • Shows partial relaxation between stimuli.
30
Q

Wave Summation

A
  • Second stimulus before relaxation causes stronger contraction.
  • Results in contractions up to 5x greater than single twitch.
31
Q

Fused (Complete) Tetanus

A
  • Sustained contraction at 80-100 stimuli/sec.
  • No time for relaxation, sustains powerful contractions.
32
Q

Motor Unit Recruitment

A
  • Increases number of active motor units for smooth movement.
  • Smaller fibers recruited first, larger fibers as force requirement increases.
33
Q

Muscle Tone:

A

Amount of tension in a muscle at rest due to weak, involuntary contractions.
Caused by constant innervation from spinal cord and higher brain centers.

34
Q

Flaccid Paralysis

A
  • Loss of muscle tone.
  • Reduced reflexes, muscle atrophy.
  • Associated with lower motor neuron injuries like trauma, ALS, Guillain-Barre Syndrome, Polio, nerve compression, and Myasthenia gravis (MG).
35
Q

Spastic Paralysis

A
  • Increased muscle tone, hyperreflexia.
  • Associated with upper motor neuron injuries like stroke, multiple sclerosis, traumatic brain injury, spinal cord injury, and cerebral palsy.
36
Q

Rigidity

A
  • Increase in muscle tone with no reflex effect, inability to relax.
  • Can occur with tetanus (Clostridium tetani infection).
  • Tetanus may also cause tetany.

Anatomy and Physiology (21 decks)

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