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Bio Med > Muscles > Flashcards

Muscles Flashcards

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Biology 101 flashcards
1
Q

What are muscles used for

A

Lift objects, move, walk, maintain posture, to circulate blood(heart), push materials through organs and tissues eg lung, gut and bladder. And allow your eyes to keep things in focus, to make your hairs stand up

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2
Q

What is cardiac muscle tissue

A

Small branched cell interconnected to other heart cells is porous junctions. Centrally located nucleus. Striated

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3
Q

Where is cardiac muscle tissue located

A

Heart

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4
Q

Innervation of cardiac muscle tissue

A

Rely on specialised auto rhythmic cardiac placement cells (sinoatrial and atrioventricular nodes) for timing of contraction.
Contra in rate altered by automatic nerves to the sinoatrial pacemaker

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5
Q

Function of cardiac muscle tissue

A

Blood circulation and maintain hydrostatic blood pressure
Works as functional syncytium

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6
Q

What is smooth muscle

A

Small spindle shaped cells tapered ends. Single, central nucleus. Non striated

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7
Q

Where is smooth muscle located

A

Located in the walls of blood vessels, around hollow organs and repsiratory, digestive, cardiovascular and reproductive tracts

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8
Q

Innervation of smooth muscle

A

Can be self contractile eg digestive tract, or requires direct innervation by autonomic/ involuntary nerves

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9
Q

Function of smooth muscle

A

Movement of food bolus, urine and reproductive tract secretions. Regulation of the diameter of airways and blood vessels. Piloerection. Works as a functional syncytium

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10
Q

What is skeletal muscle

A

Very larger striated cells. Multi nucleated. Close the plasma membrane each cell is a cellular syncytium (cytoplasmic mass containing several nuclei)

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11
Q

where is skeletal muscle located

A

Throughout the body associated it’s bones and connective tissue

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12
Q

Innervation of skeletal muscle

A

Voluntary/ somatic nerves

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13
Q

Function of skeletal muscle

A

Movement/ stabilisation of skeleton. Gaurd entrances/ exits to digestive, respiratory and urinary tracts, generates heat, protects internal organs, stores nutrient reserve

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14
Q

Prime mover (agonist)

A

Muscles whose contraction is responsible for producing a particular movement

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15
Q

Antagonist muscles

A

Work in the opposite directions to an agonist muscle to control or slow it down

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16
Q

Synergistic muscle

A

Work together in the same direction as the prime mover and assist movement

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17
Q

Fixator (type of synergistic)

A

Muscles that stabilise part of the body to prevent movement at a joint and at the origin of an agonist muscle to allow for effective controlled movement to be achieved

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18
Q

Origin point

A

Place were the fixed end of a skeletal muscle attatches to bone (proximal)

19
Q

Insertion

A

The place where muscles moveable end attatches (distal)

20
Q

Innervation of skeletal muscles by the nervous system

A

-skeletal muscles are innervated (supply an organ with neves) by motor neurones that carry efferent information from the central nervous system to the muscles via myelinated axons
-each MN axon formed a motor unit
-trunk and limbs: cell body of MNS: ventral horn of the grey matter of the spinal cord. MN axons leave the spinal cord via the ventral roots and synapse onto muscle cell fibres
-face and oropharyngeal: cell body of MNS: brain stem
Mn axons: leave the brainstem via the cranial nerves and again synapse directly onto muscle cells

21
Q

What is a motor unit

A
  • a single motor neurone and ask muscle fibres it innervates = motor unit
    -the cell bodies (soma) of all MN’s innervating a same muscle are stacked vertically in the spinal cord. This is known as a motor nucleus
22
Q

What does the CNS do in regards to the motor unit

A

-the CNS calculates the number of motor units required to produce the right level of muscle contraction
-the CNS allows them to be swapped in and out to maintain contraction over time to avoid fatigue
-the size and number of motor units in a muscle also determines level of control the CNS has over muscle contraction

23
Q

What is the neuromuscular junction

A

-each muscle fibre is innervated by only one MN
-in the area where the axon of an MN and a muscle fibre are held in close proximity, they form a clump of synapses collectively known as the neuromuscular junction
-each of these synapses is elongated and the chemicals communicate at these synapses using a small molecule called acetylcholine

24
Q

What is myasthenia

A

-sevre muscle weakness
-prevalence in uk 15/100000
-fatal as respitaoy muscle failure life expectancy 20 to 30 years before drug therapy

25
Q

What are the causes of myasthenia

A

-auto immune, anti bodies produced by patients against their own ACh receptors
-congenital, transfer of antibodies from mum to baby
-genetic, mutation affecting ACh release

26
Q

What are the symptoms of myasthenia

A

-abnormal muscle fatigue during repetitive or prolonged muscle contraction, prominent in the cranial muscles, limbs and chest
-variation in symptom severity- on a daily basis or over longer period of time

27
Q

How can tou treat myasthenia

A

-reversal of symptoms by drugs preventing ACh degradation
-test by short acting cholinesterase inhibitor: edrophonium
-treated by long lasting cholinesterase inhibitors: neostigmine, pyridostigmine

28
Q

Isometric

A

Doesn’t change length increasing tension

29
Q

Isotonic

A

Muscles change length, bearing the load

30
Q

What is myofibrils

A
  • long protein rich structures in muscles
    -made of repeating units called sacromeres
31
Q

What do sarcomeres contain

A

-parallel think protein stands: made of myosin that are free from any permeant point of attatchment
-thin and thick strands are organised in an interdigiated manner within the sarcomeres
-the sarcomere is the basic contractile unit of the muscle fibre

32
Q

What is the sliding filament theory

A

1)Calcium binds to tropin which frees the actin from tropomyosin.
2)ATP binds to myosin
3)This creates ADP and Pi = cock and bind (myosin head can move and bind to actin)
4)ADP and Pi leaves =power stroke
5)ATP binds= release
6)repeat

33
Q

What id excitation - contraction coupling in each muscle cell

A

-at rest : low calcium in sarcoplasm
-excitation initiation of muscle fibre ap: excitation of membrane
Calcium exported out of SR
-high calcium in sarcoplasm causes muscle contraction
-end of muscle fibre ap: calcium pumped back into SR so low calcium in sarcoplasm causes contraction to stop
-excitation ( of a muscle cell membrane) and contraction (of a muscle cell) occur nearly simultaneously eg they are coupled

34
Q

Contraction efficiency and sarcomere overlap :

A

-sacromeres (=muscle) too stretched or too contracted equals a decreased cross bridge formation due to limited overlap or hindrance, respectively less tension that can be generated
-optimal sarcomere light equals optimum cross bridge formation equals maximum tension (80%-120% of the resting length)

35
Q

What are muscle cells made of

A

Myofibril

36
Q

What is myofibrils made of

A

Contractile proteins
Myofilaments

37
Q

What are myofilaments

A

Actin (thin)
Myosin (thick)

38
Q

Step 1 of sliding filament theory

A

Calcium binds releasing troponin= free actin

39
Q

Step 2 of sliding filament theory

A

ATP binds to myosin (creating adp so it can move)

40
Q

Step 3 of sliding filament theory

A

Adp + pi is created= cock and bind

41
Q

Step 4 of sliding filament theory

A

Adp + pi leaves= power stroke

42
Q

Step 5 of sliding filament theory

A

ATP binds= release

43
Q

Step 6 of sliding filament theory

A

Repeat= shortening skeletal muscle

Bio Med (24 decks)

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