Lab Exam 2 Flashcards

1
Q

Metabolism

A

sum of all chemical reactions that take place in the body

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2
Q

Hormone

A

a regulatory signaling molecule created by endocrine organs & transported through the blood to stimulate a response

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3
Q

Target Cell

A

the cell that responds to the chemical messenger

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4
Q

Receptor

A

the proteins on a target cell that recognize & bind a chemical messenger

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5
Q

3 structural classes of hormones

A

-amines
-peptides
-steroids

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6
Q

Amines

A

derived from amino acids & contain amine groups

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7
Q

Examples of amines

A

dopamine, norepi, epi, thyroid hormones, histamine

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8
Q

Peptides

A

chains of 50 or less amino acids

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9
Q

Steroids

A

synthesized on demand from cholesterol, immediate release due to hydrophobic characteristics

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10
Q

G protein coupled receptor (GPCR)

A
  1. 1st messenger binds to receptor & activates G protein
  2. G protein releases alpha subunit, GDP to GTP, alpha subunit binds to adenylate cyclase
  3. Adenylate cyclase turns ATP to cAMP
  4. cAMP activates protein kinase A
  5. protein kinase A phosphorylates protein to alter activity using ATP
  6. cell response triggered
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11
Q

Enzyme linked receptor

A
  1. messenger binds to receptor causing change in conformation
  2. tyrosine kinase activated
  3. tyrosine kinase phosphorylates intracellular protein
  4. cell response triggered
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12
Q

Channel linked receptor

A

receptor & ion channel are the same protein

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13
Q

Thyroid Axis

A
  1. hypothalamus releases TRH to activate pituitary gland
  2. pituitary gland releases TSH to activate thyroid
  3. thyroid releases T4 & T3
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14
Q

How does thyroid hormone affect metabolism?

A

increases Na/K pump

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15
Q

What are the units for BMR?

A

ml O2/kg/hr

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16
Q

How can BMR be affected clinically?

A

-BMR will be low if TRH or TSH levels are low
-Thyroxine injections can increase BMR

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17
Q

Hypophysectomy

A

removal of pituitary gland

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18
Q

Thyroidectomy

A

removal of thyroid gland

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19
Q

How does estrogen affect bone density?

A

-it stimulate bone growth & density & protects against osteoporosis

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20
Q

Which hormone replacement therapies would be used to counteract osteoporosis?

A

estrogen & calcitonin injections

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21
Q

Normal T score range

A

+1 to -0.99

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22
Q

Osteopenia T score range

A

-1 to -2.49

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23
Q

Osteoporosis T score range

A

-2.5 or lower

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24
Q

When is insulin released?

A

secreted by beta cells in the pancreas in response to high blood glucose levels

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25
Q

When is glucagon released?

A

secreted by alpha cells in the pancreas in response to low blood glucose levels

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26
Q

What are the effects of alloxan?

A

Induces diabetes mellitus, ROS destroys pancreatic beta cells & causes hyperglycemia due to no release of insulin

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27
Q

HPA Axis

A
  1. hypothalamus releases CRH to activate anterior pituitary
  2. anterior pituitary release ACTH to activate adrenal cortex
  3. adrenal cortex releases cortisol
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28
Q

Cushing’s Syndrome

A

high cortisol level, low ACTH levels
primary endocrine disorder

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29
Q

Cushing’s Disease

A

high levels of cortisol & ACTH
secondary endocrine disorder

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30
Q

Addison’s Disease

A

low cortisol level, high ACTH level
primary endocrine disorder

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31
Q

Primary endocrine disorders

A

abnormality in the endocrine organ

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32
Q

Secondary endocrine disorders

A

abnormality in the hormone

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33
Q

3 parts of a neuron

A

soma, dendrites, axon

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34
Q

Excitability

A

the ability to respond to stimuli & convert them into action potentials

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35
Q

Conductivity

A

capability of transmitting an action potential along the length of the cell

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36
Q

Where on the neuron does an action potential occur?

A

axon

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37
Q

Electrochemical gradient

A

sum of the electrical and chemical gradients acting on an ion

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38
Q

Equilibrium potential

A

the membrane potential when the electrical driving force is equal in magnitude & opposite in direction to the chemical driving force giving an electrochemical driving force of zero

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39
Q

Formula for equilibrium potential

A

61/charge of ion times log (extracellular fluid/ intracellular fluid)

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40
Q

ICF concentration for K+

A

140

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41
Q

ECF concentration for K+

A

4

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42
Q

ICF concentration for Na+

A

15

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43
Q

ECF concentration for Na+

A

145

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44
Q

ICF concentration for Ca2+

A

less than 0.001

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45
Q

ECF concentration for Ca2+

A

1.8

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46
Q

Subthreshold stimulus

A

stimulus that is too small in magnitude to produce an action potential

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47
Q

Depolarization

A

voltage gated Na+ channels are open, brings membrane back to threshold (0)

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48
Q

Hyperpolarization

A

K+ channels open & K+ moves out of the cell, membrane potential becomes more negative

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48
Q

Threshold Stimulus

A

minimum intensity required from a stimulus to produce a response

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49
Q

Absolute refractory period

A

period where all Na+ channels are closed & the cell cannot be stimulated at all

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50
Q

Relative refractory period

A

period where some Na+ channels reset to open (can pump some Na+ into the cell), a stronger stimulus is needed to stimulate cell

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51
Q

What are the effects of nerve size & myelination on conduction velocity?

A

myelination increases the rate of an action potential
a large diameter increases the rate of an action potential

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52
Q

Tetrodotoxin (TTX)

A

blocks voltage gated Na+ channels that are needed to produce an action potential

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53
Q

Curare

A

block acetylcholine receptor

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54
Q

Lidocaine

A

blocks Na+ flux across a membrane

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55
Q

Ether

A

opens K+ ion channels causing the neuron to become hyperpolarized

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56
Q

Epimysium

A

surrounds the entire muscle

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57
Q

Perimysium

A

surrounds the fascicle

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58
Q

Endomysium

A

surrounds individual muscle fibers

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59
Q

Fiber

A

muscle cells

60
Q

Fascicle

A

bundle of muscle cells

61
Q

Motor unit

A

smallest functional contractile entity within a muscle
contains a single motor neuron & all the muscle fibers it innervates

62
Q

Sarcolemma

A

plasma membrane of muscle cells

63
Q

Myofibril

A

contains the myofiliment

64
Q

Myofiliment

A

the muscles contractile machinery
thick & thin

65
Q

Actin

A

thin filament that has myosin binding site

66
Q

Myosin

A

makes up thick filaments
formed in dimers

67
Q

Crossbridge

A

head of myosin
site of myosin/ actin binding

68
Q

Troponin

A

protein located on thin filament (3 subunits)

69
Q

Tropomyosin

A

long protein that is positioned over actin binding sites

70
Q

Sarcoplasmic reticulum

A

modified smooth ER that stores Ca2+

71
Q

T-tubule

A

deep in muscle fiber, releases Ca2+ after action potential

72
Q

Sarcomere

A

Z line to Z line
has an A band, H zone, M line, I band, Z line

73
Q

Z line

A

borders sarcomere

74
Q

Titan

A

holds thick filaments in place

75
Q

Alpha somatic motor neuron

A

neuron that supplies one motor unit

76
Q

Synaptic vesicle

A

in neuron, released when Ca2+ enters the cell

77
Q

Acetylcholine

A

neurotransmitter in the synaptic vesicle

78
Q

Nicotinic receptors

A

where acetylcholine binds to open ligand-regulated Na/K channels

79
Q

Ligand-regulated Na/K channels

A

depolarization of muscle membrane

80
Q

Voltage-regulated Na+ channels

A

open during depolarization resulting in an action potential

81
Q

What is the excitation-contraction coupling mechanism for skeletal muscle?

A
  1. dendrites & alpha somatic neurons get stimulated
  2. action potential moves through t-tubule deep into muscle fiber
  3. thick & thin filaments slide together
  4. Ca2+ released from sarcoplasmic reticulum
  5. Ca2+ binds to troponin
  6. tropomyosin moves & exposes the active binding site of actin
  7. cross bridge cycling occurs
82
Q

What is the process of cross-bridge cycling?

A
  1. ATP is hydrolyzed
  2. myosin binds to actin releasing Pi
  3. myosin head pivots
  4. ADP is released (low energy state)
    CAN ONLY OCCUR WHEN Ca2+ IS PRESENT
83
Q

Isometric muscle contraction

A

a muscle contraction when the muscle length does not change

84
Q

Latent period of an isometric twitch

A

time between the initiation of the stimulus & the beginning of force generation by the muscle
time before Ca2+ is released

85
Q

Contraction of an isometric twitch

A

time before peak muscle tension development
Ca2+ is binding to troponin & crossbridge cycling is increasing

86
Q

Relaxation of an isometric twitch

A

time between peak contraction & the end of contraction
Ca2+ is pumped back into SR

87
Q

Threshold stimulus

A

minimum stimulus required to initiate contraction

88
Q

Maximal stimulus

A

weakest stimulus where all motor units are being stimulated

89
Q

What is the role of motor unit recruitment in determining the strength of a muscle contraction?

A

more motor units are recruited to contract due to an increased stimulus strength thus an increased contractile force

90
Q

Series elastic component

A

connective tissue with the sarcomere
passive tension

91
Q

Contractile component

A

makes up the sarcomere
active tension

92
Q

Passive tension

A

produced from stretching

93
Q

Active tension

A

produced by processes in the sarcomere

94
Q

Summation

A

addition of an action potential resulting in increased tension

95
Q

Incomplete (unfused) tetanus

A

plateau is reached & individual action potentials are distinguishable

96
Q

Complete (fused) tetanus

A

tension plateau, individual action potentials are not distinguishable

97
Q

Muscle fatigue

A

decline in the muscles ability to maintain a contractile force

98
Q

How is muscle fatigue affected by low stimulus rate?

A

no muscle fatigue rate seen

99
Q

How is muscle fatigue affected by moderate stimulus rate?

A

fatigue is reached in a shorter time

100
Q

How is muscle fatigue affected by rapid stimulus rate?

A

tetanus is reached & fatigue occurs at its fastest rate

101
Q

How do you calculate muscle fatigue?

A

change in force divided by change in time
WILL GIVE A NEGATIVE NUMBER

102
Q

Isotonic muscle contraction

A

contraction where the stimulus can overcome a load

103
Q

Concentric contraction

A

muscle shortening under a load

104
Q

Eccentric contraction

A

muscle lengthening under a load

105
Q

What controls the production of T4 (thyroxine)?

A

pituitary gland

106
Q

What secretes TSH?

A

pituitary gland

107
Q

What secretes T4 (thyroxine)?

A

thyroid gland

108
Q

What does the release of TSH cause in the thyroid gland?

A

causes thyroid gland to increase in size & secrete T3 & T4 into the bloodstream

109
Q

What happens if TSH levels are too high?

A

thyroid gland enlarges resulting in goiter

110
Q

How does negative feedback influence hormone release on the thyroid axis?

A

as circulation levels of T4 get low, the hypothalamus secretes more TRH to start the thyroid axis cycle over again, thus producing more T4

111
Q

What is T score & how is it determined?

A

measure of bone density
determined by comparing a persons bone density to that of a healthy 30 yr olds of the same sex

112
Q

Type 1 diabetes mellitus

A

pancreas does not produce enough insulin

113
Q

Type II diabetes mellitus

A

body does not respond to the circulating insulin

114
Q

HPA axis (cortisol release pathway)

A
  1. hypothalamus releases CRH
  2. CRH stimulates anterior pituitary
  3. anterior pituitary releases ACTH
  4. ACTH stimulates adrenal cortex
  5. adrenal cortex releases cortisol
115
Q

What is the HPA axis regulating in the body?

A

cortisol levels, which have a direct relation to bone density, much like estrogen

116
Q

Which type of receptor will bind a hydrophobic chemical messenger?

A

GPCR

117
Q

What is the most important hormone for maintaining metabolic rate?

A

T4 (thyroxine)

118
Q

How do you calculate BMR?

A

(ml O2 consumed in 1 minute times 60) (weight in kg)

119
Q

How do BMR & hormone levels look in a thyroidectomized individual?

A

low thyroid & BMR rates (below 1600)

120
Q

How do BMR & hormone levels look in a hypophysectomized individual?

A

low thyroid & BMR rates (below 1600)

121
Q

Which ion predominantly affects resting membrane potential?

A

K+ because the cell membrane is much more permeable to it than anything else

122
Q

Where is an action potential generated?

A

axon hillock

123
Q

Where is a graded potential generated?

A

soma & dendrite

124
Q

What is resting membrane potential?

A

potential difference between the inside & the outside of the cell when cell is not being stimulated

125
Q

What is graded potential?

A

a relatively small change in resting membrane potential produced by a stimulus that opens ligand gated ion channels and depolarizes the membrane to threshold (for an action potential)
strength of the graded potential is related to the strength of the stimulus

126
Q

What is an action potential?

A

a large change in resting membrane potential produced by the opening of voltage gated channels in response to a graded potential that depolarized the membrane to threshold

127
Q

What is a compound action potential

A

the net effect of all action potentials in an entire nerve

128
Q

What are the events of an action potential?

A

DEPOLARIZATION
1. Na+ voltage gated ion channels open, allowing Na+ into the cell
2. cell membrane potential increases
3. activation gates open, inactivation gates close
REPOLARIZATION
1. K+ moves out of the cell
2. membrane potential becomes more negative
AFTER-HYPERPOLARIZATION
1. after reaching resting membrane potential, voltage gated K+ channels close
2. Na/K pump restores resting membrane potential

129
Q

What is depolarization?

A

Na+ moves into the cell, membrane potential increases

130
Q

What is repolarization?

A

K+ moves out of the cell, membrane potential decreases

131
Q

What is a synapse?

A

point of contact between neurons where communication occurs
site of neurotransmitter release

132
Q

How would an action potential be altered with an increase of stimulus voltage?

A

increasing stimulus would increase the frequency of action potentials

133
Q

What would happen to neurotransmitter release when extracellular Ca2+ levels were 0?

A

with no Ca2+ present, Ca2+ channels are closed so there would be no neurotransmitters released from the axon

134
Q

Length tension curve for isometric contraction

A

-decreased length: causes overlap of actin, less tension generation (left side)
-optimum length: actin &myosin generate the most tension (top straight part)
-increased length: stretching of actin away from myosin (right side)

135
Q

Force-velocity curve for isotonic contraction

A

velocity is highest when load is lowest
as load increases velocity decreases until it hits 0 where the load is greater than the tension of the muscle

136
Q

Electrical stimulator

A

delivered amount & duration of stimulating voltage to muscle via electrodes

137
Q

Mounting stand

A

includes forces transducer to measure amount of force developed by muscle

138
Q

Oscilloscope

A

displays stimulated muscle twitch & amount of all the forces developed by the muscle; also used to observe voltage changes

139
Q

Microelectrode

A

a probe with a very small tip that can impale a single neuron

140
Q

Microelectrode amplifier

A

measures voltage between microelectromechanical & a reference

141
Q

Stimulator

A

used to select the stimulus modality

142
Q

Recording electrode wires

A

used to record voltage changes in the axon

143
Q

Hook electrodes

A

used to record extracellular voltage changes in the axon

144
Q

Manometer

A

U-shaped tube containing fluid

145
Q

Spectrophotometer

A

used to measure the amount of light absorbed or transmitted

146
Q

Dual X-ray absorptiometry bone-density scanner (DXA)

A

measures vertebral bone density

147
Q

HPLC detector

A

provides hormone concentration to patient