Muscles Flashcards Preview

A&p > Muscles > Flashcards

Flashcards in Muscles Deck (48)
Loading flashcards...
0
Q

Direct attachment?

Indirect attachment?

A

Direct - Epimysium&periosteum/perichondrium fused

Indirect - ct wrappings extend beyond muscle as a rope like tendon

1
Q

What are the 3 muscle layers?

A

Epimysium - dense reg
Perimysium - fibrous ct
Endomysium - areolar

2
Q

7 things a skeletal muscle contains?

A

Myofibrils, nuclei, sarcolemma, sarcoplasma, t tubules, sarcoplasmic reticulum, triad

3
Q

What does sarcoplasm contain?

A

Mitochondria, glycosomes, myoglobin, myofibrils

4
Q

Function of tropinin?

A

Holds tropomysin in place

5
Q

Function if tropomysin?

A

Blocks binding site

Control switch for contraction

6
Q

I band?

A

Light, z disc in middle, actin

7
Q

Z disc?

A

Sheet of alpha actinin the anchors filaments

8
Q

A bands?

A

Dark filament between I bands, contains actin and myosin

9
Q

H zone?

A

Lighter zone, only myosin, in middle of a

10
Q

M line?

A

Dark, middle of h, contains myomesin which anchors myosin filaments

11
Q

What are elastic filaments made of, where are they located and what is their function?

A

Protein Titin
Z–>M through myosin
Recoil to original length

12
Q

When does shortening occur?

A

When tension generated by cross bridges on actin exceeds forces opposing the shortening.

13
Q

What is activation?

A

Neural stimulation at junction

14
Q

Excitation-contraction coupling?

A

Generation/ propagation of ap along sarcolemma to the contraction

15
Q

Where are neuromuscular junctions located ?

A

Half way along muscle

16
Q

How does initiation of contraction reach t -tubules?

A

Nerve is stimulated along axon -> ca channels open and enter axon-> ca triggers vesicles to release ach into cleft->goes to receptors on sarcolemma->action potential initiated in sarcolemma->chem regulated na open and it moves in, slight depolarizers ->triggers voltage na channels to open -> membrane depolarizers to created AP-> after ap passes na shuts, k opens and moves out-> repolarization-> na/k pumps restore balance-> ap travels along sarcolemma and destruction of ach

17
Q

Sliding filament?

A

Ap at sarcomere ➡️t tubules➡️voltage sensitive proteins stimulate release of ca from SR➡️ca binds to tropinin➡️changes shape and moves tropomysin away from actin binding sites➡️ ATP binds to head and hydrolisizes to adp and pi➡️ head becomes cocked and form cross bridges➡️head changes shape producing power stroke and actin is pulled inwards➡️adp and pi release and new apt binds and continues

Process with go on till apt or ca ions not available

18
Q

Refractory period?

A

When membrane needs to be repolarized before it can be stimulated agAin

19
Q

3 roles of calcium in contraction?

A

To be released in axon terminal to release ach into cleft
To bind to tropinin to move tropomysin off actin binding sites
Extra calcium in sarcolemma binds to calmodulin activating kinases which converts glycogen to glucose for ATP production

20
Q

What is tension?

A

Force exerted on a load

21
Q

What is an isometric contraction?

A

No shortening, muscle tension ⬆️ but doesn’t exceed load

22
Q

What is isotonic contraction and what are the two types?

A

Shortening because tension>load
Concentric - shortens
Eccentric - lengthens(balance)

23
Q

What is a motor unit?

A
Motor neuron and fibers it supplies
Small-fine moving
Large- weight bearing movements
Weak contraction
Asynchronous
24
Q

What is a muscle twitch and what are it’s three phases?

A

Response to single stimulus
Latent-e-c coupling
Contraction- cross bridge form, tension⬆️
Relaxation-ca renters SR, tension=0

25
Q

What are responses graded by?

2

A

Frequency

strength -⬆️stimulus =⬆️recruitment= ⬆️strength

26
Q

Threshold stimulus ?

Max stimulus?

A

Min strength needed to cause first visible contraction

Max contraction occurs

27
Q

What is muscle tone, and what does it do for us?

A

Slightly contracted due to spinal reflexes activating motor units in response to input from stretch receptors
Firm healthy excitable

28
Q

Direct phosphorylation of ADP? Formula?

A

CreatineP04 ➡️ creatine➕po4

Po4 +adp ➡️ATP

29
Q

What is anaerobic pathways? What happens and who uses them?

A

Blood vessels compressed->o2 delivery impaired
Pyruvic acid➡️lactic-> blood
Liver kidney heart
Liver converts it back into Pyruvic acid

30
Q

Aerobic respiration? What is it used during? and what is used first?

A

Rest, light and moderate exercise

Glycogen>blood glucose> Pyruvic acid from gylcolysis> fatty acids

31
Q

What is muscle fatigue and why does it happen?

A

Inability to contract or respond to stimulus
Ionic Imbalance ca2 depletion lack of ATP
O2 deficit – o2 reserves, myoglobin, glycogen stores, atp/ cp reserves need to be replenished and lactic acid needs to return to pyruvic, glucose and glycogen

32
Q

What is the force of a muscle contraction affected by?

A

Recruitment
Size - increases strength
Frequency - time for more effective transfer of tension to non contractile components
Length tension relationship

33
Q

Velocity and duration of contraction are affected by?

A

Muscle fiber - speed of contraction, metabolic pathways for ATP
Load -⬆️load➡️⬆️latent➡️⬇️contraction➡️ ⬇️duration
Recruitment - more recruited, faster, longer

34
Q

3 types of metabolic pathway fibers?

A

Slow oxidative - slow contracting& fatiguing **endurance
Fast oxidative - middle **sprinting and walking
Fast glycolytic - fast contract/fatigue
** short term high energy activities

35
Q

What does aerobic exercise lead to?

A

⬆️muscle capillaries
⬆️mitochondria
⬆️myoglobin synthesis
⬆️endurance, strength, resistance to fatigue
**may convert glycolytic fibers to fast oxidative

36
Q

Anaerobic exercise results in?

A

Muscle hypertrophy

⬆️mitochondria, myofilaments, glycogen stores and CT

37
Q

Structure of smooth muscle?

A

One nucleus, spindle shaped cells
Endomysium only
Actin and myosin

38
Q

Where is calcium stored in smooth muscle?

A

Caveolae which are indentations in membrane

39
Q

Innervation of smooth muscle?

A

Autonomic nerve fibers @diffuse junctions

Varicosities of nerve fibers store and release nts

40
Q

Myofilaments in a smooth muscle?

A

Fewer myosin compared to actin than in skeletal
Myosin has heads along whole length
Calmodulin binds with ca.. No trop
Spirally arranged, contract like corkscrew
Body proteins anchor intermediate filaments to sarcolemma

41
Q

Characteristics of a smooth muscle contraction?

A
Slow, synchronous
Cells have gap junctions
Rate&intensity modified by stimuli
Can divide
Pacemaker cells -stimulate whole con
Energy efficient, slow, longer lasting
42
Q

Stress-relaxation response of smooth muscle?

A

Briefly responds to stretch then adapts
Can still contract on demand
Storage

43
Q

Neural regulation of a smooth muscle contraction?

A

⬆️ or ⬇️ in ca in sarcoplasm

Response depends on neurotransmitter released and the type of receptor

44
Q

What does ach do in neural regulation of smooth muscle contraction?

A

Contracts bronchioles

45
Q

What does norepinephrine do in neural regulation of smooth muscles?

A

Contracts bv walls

Inhibts bronchioles contraction

46
Q

Single unit smooth muscle?

A
Rhythmical contractions
Gap junctions
Spontaneous AP
Opposing sheets
Stress-relaxation response
Most common: hollow orgs
47
Q

Multi unit smooth muscle?

A

Large airways, arteries, a rector pilli, iris
Motor units
Graded contractions occur in response to neural stim
Not synchronous