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Physiology > Lecture #2 > Flashcards

Lecture #2 Flashcards

1
Q

Characteristics of muscles

A
  1. Excitability (responsiveness)
  2. Conductivity
  3. Contractility
  4. Extensibility
  5. Elasticity
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2
Q

Types of muscles

A
  1. Skeletal
  2. Cardiac
  3. Smooth
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3
Q

Myofilaments – the functional contractile unit

A
  • Muscles shorten b/c their individual sarcomeres shorten

Neither thick nor thin filaments change length during shortening - Only the amount of overlap changes

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4
Q

Sliding Filament Thoery

A

Thick and thin filaments slide over one another = sliding filament theory

Elastic filaments (titin) stabilize thick filament and allows recoil

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5
Q

Myofilaments - Thick

A

Made of several hundred myosin molecules, shaped like a golf club
Heads directed outward in a helical array around the bundle


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6
Q

Myofilaments - Thin Filaments

A
  1. Fibrous (F) actin: two intertwined strands
    • String of globular (G) actin subunits each with an active site that can
    bind to head of myosin molecule 2. Tropomyosin
    • Blocks active sites on G actin subunits
  2. Troponin
    • Calcium-binding protein on each tropomyosin molecule
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7
Q

2 kinds of muscles

A
  1. Striated Muscles - have sarcomeres, and alternating light and dark bands
  2. Smooth Muscle
    lack sacromeres
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8
Q

Striations

A 
Dark = A band -- thick (myosin) and thin (actin) overlap
Light = I band -- thin filaments (actin) only
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9
Q

Nerve Relationship

A

skeletal muscles never contracted unless stimulated by a nerve

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10
Q

Muscle fibers of one motor unit

A
  • contract in unison
  • dispersed throughout muscle (large SA = weaker contraction)
  • long term contraction
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11
Q

Excitation

A

nerve action potentials = muscle action potentials

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12
Q

Excitation-contraction coupling

A

link action potentials on sacrolemma to activation of the myoflimates … preparing them to contract

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13
Q

Contraction

A

muscle fibers develop tensions and shortens

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14
Q

Relaxation

A

relaxes and turns to resting length

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15
Q

The process of Excitation

A
  1. Voltage-gated Ca+ channels open in synaptic knob
  2. Ca+ enters, which causes the release of ACh
  3. ACh binds to receptor
  4. Na enters = end plate which opens and creates action potential
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16
Q

The process of Excitation-contraction Coupling

A
  1. Action potential spreads down T tubules
  2. Open voltage-gated ion channels in T tubules and Ca channels in SR
  3. Ca leaves SR and
    enters cytosol, binds to troponin = exposure of active sites on actin
17
Q

The process of Contraction

A
  1. ATPase in myosin head hydrolyzes ATP
  2. Activates the head “cocking” it in an extended position
    • ADP + Pi remain attached
  3. Head binds to actin active site forming a myosin–actin cross- bridge
  4. Myosin releases ADP and Pi, and flexes pulling thin filament with it = power stroke
18
Q

Latent Period

A

delay between stimulus and contraction

19
Q

Contraction Phase

A

time when muscle generates external tension

20
Q

Relaxation phase

A

—time when tension declines to baseline

21
Q

Recruitment or multiple motor unit (MMU) summation

A

Occurs according to the size principle

22
Q

Isometric Contraction

A

Muscle produces internal tension but external resistance causes it to stay the same length – Stablizing

23
Q

Isotonic Contraction

A

Muscle changes in length with no change in tension

24
Q

Sensory Receptors and its general properties

A

a structure specialized to detect a stimulus

  1. Transduction—the conversion of stimulus energy into nerve signals
  2. Receptor potential—small local electrical change on a receptor
    cell
25
Q

Sensation

A

a subjective awareness of the stimulus

26
Q

Sensory Receptores

A
  1. Afferent neurons
  2. Epithelial Cells
    both send signal to integrating centre
27
Q

Phasic receptors

A

adapt rapidly, smell, hair movement

28
Q

Tonic Receptors

A

adapt slowly, body position, joint movement

29
Q

Free nerve endings

A

for pain and temperature

located in skin and mucous membrane

30
Q

Tactile (Merkel discs)

A

for light touch and tecture

31
Q

Hair receptors

A

monitor movement of the hair

32
Q

Somatosensory Projection Pathways

A

from receptor to brain
1st order neuron
2nd order neuron
3rd order neuron

33
Q

The Chemical Senses

A 
Taste (Gustation):
• stimulants on taste
buds
• Tastants must dissolve in saliva
• Smell (Olfaction):
• Response to odorants
34
Q

The Five Primary sensations of taste

A 
1. Salty:
• by metal ions 
2. Sweet:
• associated with carbohydrates 
3. Sour:
• acids such as in citrus fruits 
4. Bitter:
• associated with spoiled foods 
5. Umami:
• “meaty” taste of amino acids
35
Q

Hearing and Equilibrium

A

Hearing - a response to vibrating air molecules

Equilibrium- the sense of motion, body orientation, and balance

36
Q
  1. Sound
  2. Loudness
  3. Pitch
A

1.any audible vibration of molecules

  1. the perception
    of sound energy, intensity, or amplitude of the vibration in decibels (dB)
  2. sense of whether a sound is “high” or “low”
    vibration frequency: hertz (Hz) or cycles/second

Physiology (9 decks)

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