Lab Exam 2 Flashcards
(148 cards)
1
Q
Metabolism
A
sum of all chemical reactions that take place in the body
2
Q
Hormone
A
a regulatory signaling molecule created by endocrine organs & transported through the blood to stimulate a response
3
Q
Target Cell
A
the cell that responds to the chemical messenger
4
Q
Receptor
A
the proteins on a target cell that recognize & bind a chemical messenger
5
Q
3 structural classes of hormones
A
-amines
-peptides
-steroids
6
Q
Amines
A
derived from amino acids & contain amine groups
7
Q
Examples of amines
A
dopamine, norepi, epi, thyroid hormones, histamine
8
Q
Peptides
A
chains of 50 or less amino acids
9
Q
Steroids
A
synthesized on demand from cholesterol, immediate release due to hydrophobic characteristics
10
Q
G protein coupled receptor (GPCR)
A
- 1st messenger binds to receptor & activates G protein
- G protein releases alpha subunit, GDP to GTP, alpha subunit binds to adenylate cyclase
- Adenylate cyclase turns ATP to cAMP
- cAMP activates protein kinase A
- protein kinase A phosphorylates protein to alter activity using ATP
- cell response triggered
11
Q
Enzyme linked receptor
A
- messenger binds to receptor causing change in conformation
- tyrosine kinase activated
- tyrosine kinase phosphorylates intracellular protein
- cell response triggered
12
Q
Channel linked receptor
A
receptor & ion channel are the same protein
13
Q
Thyroid Axis
A
- hypothalamus releases TRH to activate pituitary gland
- pituitary gland releases TSH to activate thyroid
- thyroid releases T4 & T3
14
Q
How does thyroid hormone affect metabolism?
A
increases Na/K pump
15
Q
What are the units for BMR?
A
ml O2/kg/hr
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
17
Q
Hypophysectomy
A
removal of pituitary gland
18
Q
Thyroidectomy
A
removal of thyroid gland
19
Q
How does estrogen affect bone density?
A
-it stimulate bone growth & density & protects against osteoporosis
20
Q
Which hormone replacement therapies would be used to counteract osteoporosis?
A
estrogen & calcitonin injections
21
Q
Normal T score range
A
+1 to -0.99
22
Q
Osteopenia T score range
A
-1 to -2.49
23
Q
Osteoporosis T score range
A
-2.5 or lower
24
Q
When is insulin released?
A
secreted by beta cells in the pancreas in response to high blood glucose levels
25
When is glucagon released?
secreted by alpha cells in the pancreas in response to low blood glucose levels
26
What are the effects of alloxan?
Induces diabetes mellitus, ROS destroys pancreatic beta cells & causes hyperglycemia due to no release of insulin
27
HPA Axis
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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Cushing's Syndrome
high cortisol level, low ACTH levels
primary endocrine disorder
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Cushing's Disease
high levels of cortisol & ACTH
secondary endocrine disorder
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Addison's Disease
low cortisol level, high ACTH level
primary endocrine disorder
31
Primary endocrine disorders
abnormality in the endocrine organ
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Secondary endocrine disorders
abnormality in the hormone
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3 parts of a neuron
soma, dendrites, axon
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Excitability
the ability to respond to stimuli & convert them into action potentials
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Conductivity
capability of transmitting an action potential along the length of the cell
36
Where on the neuron does an action potential occur?
axon
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Electrochemical gradient
sum of the electrical and chemical gradients acting on an ion
38
Equilibrium potential
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
39
Formula for equilibrium potential
61/charge of ion times log (extracellular fluid/ intracellular fluid)
40
ICF concentration for K+
140
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ECF concentration for K+
4
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ICF concentration for Na+
15
43
ECF concentration for Na+
145
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ICF concentration for Ca2+
less than 0.001
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ECF concentration for Ca2+
1.8
46
Subthreshold stimulus
stimulus that is too small in magnitude to produce an action potential
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Depolarization
voltage gated Na+ channels are open, brings membrane back to threshold (0)
48
Hyperpolarization
K+ channels open & K+ moves out of the cell, membrane potential becomes more negative
48
Threshold Stimulus
minimum intensity required from a stimulus to produce a response
49
Absolute refractory period
period where all Na+ channels are closed & the cell cannot be stimulated at all
50
Relative refractory period
period where some Na+ channels reset to open (can pump some Na+ into the cell), a stronger stimulus is needed to stimulate cell
51
What are the effects of nerve size & myelination on conduction velocity?
myelination increases the rate of an action potential
a large diameter increases the rate of an action potential
52
Tetrodotoxin (TTX)
blocks voltage gated Na+ channels that are needed to produce an action potential
53
Curare
block acetylcholine receptor
54
Lidocaine
blocks Na+ flux across a membrane
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Ether
opens K+ ion channels causing the neuron to become hyperpolarized
56
Epimysium
surrounds the entire muscle
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Perimysium
surrounds the fascicle
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Endomysium
surrounds individual muscle fibers
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Fiber
muscle cells
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Fascicle
bundle of muscle cells
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Motor unit
smallest functional contractile entity within a muscle
contains a single motor neuron & all the muscle fibers it innervates
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Sarcolemma
plasma membrane of muscle cells
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Myofibril
contains the myofiliment
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Myofiliment
the muscles contractile machinery
thick & thin
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Actin
thin filament that has myosin binding site
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Myosin
makes up thick filaments
formed in dimers
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Crossbridge
head of myosin
site of myosin/ actin binding
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Troponin
protein located on thin filament (3 subunits)
69
Tropomyosin
long protein that is positioned over actin binding sites
70
Sarcoplasmic reticulum
modified smooth ER that stores Ca2+
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T-tubule
deep in muscle fiber, releases Ca2+ after action potential
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Sarcomere
Z line to Z line
has an A band, H zone, M line, I band, Z line
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Z line
borders sarcomere
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Titan
holds thick filaments in place
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Alpha somatic motor neuron
neuron that supplies one motor unit
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Synaptic vesicle
in neuron, released when Ca2+ enters the cell
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Acetylcholine
neurotransmitter in the synaptic vesicle
78
Nicotinic receptors
where acetylcholine binds to open ligand-regulated Na/K channels
79
Ligand-regulated Na/K channels
depolarization of muscle membrane
80
Voltage-regulated Na+ channels
open during depolarization resulting in an action potential
81
What is the excitation-contraction coupling mechanism for skeletal muscle?
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
What is the process of cross-bridge cycling?
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
Isometric muscle contraction
a muscle contraction when the muscle length does not change
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Latent period of an isometric twitch
time between the initiation of the stimulus & the beginning of force generation by the muscle
time before Ca2+ is released
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Contraction of an isometric twitch
time before peak muscle tension development
Ca2+ is binding to troponin & crossbridge cycling is increasing
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Relaxation of an isometric twitch
time between peak contraction & the end of contraction
Ca2+ is pumped back into SR
87
Threshold stimulus
minimum stimulus required to initiate contraction
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Maximal stimulus
weakest stimulus where all motor units are being stimulated
89
What is the role of motor unit recruitment in determining the strength of a muscle contraction?
more motor units are recruited to contract due to an increased stimulus strength thus an increased contractile force
90
Series elastic component
connective tissue with the sarcomere
passive tension
91
Contractile component
makes up the sarcomere
active tension
92
Passive tension
produced from stretching
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Active tension
produced by processes in the sarcomere
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Summation
addition of an action potential resulting in increased tension
95
Incomplete (unfused) tetanus
plateau is reached & individual action potentials are distinguishable
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Complete (fused) tetanus
tension plateau, individual action potentials are not distinguishable
97
Muscle fatigue
decline in the muscles ability to maintain a contractile force
98
How is muscle fatigue affected by low stimulus rate?
no muscle fatigue rate seen
99
How is muscle fatigue affected by moderate stimulus rate?
fatigue is reached in a shorter time
100
How is muscle fatigue affected by rapid stimulus rate?
tetanus is reached & fatigue occurs at its fastest rate
101
How do you calculate muscle fatigue?
change in force divided by change in time
WILL GIVE A NEGATIVE NUMBER
102
Isotonic muscle contraction
contraction where the stimulus can overcome a load
103
Concentric contraction
muscle shortening under a load
104
Eccentric contraction
muscle lengthening under a load
105
What controls the production of T4 (thyroxine)?
pituitary gland
106
What secretes TSH?
pituitary gland
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What secretes T4 (thyroxine)?
thyroid gland
108
What does the release of TSH cause in the thyroid gland?
causes thyroid gland to increase in size & secrete T3 & T4 into the bloodstream
109
What happens if TSH levels are too high?
thyroid gland enlarges resulting in goiter
110
How does negative feedback influence hormone release on the thyroid axis?
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
What is T score & how is it determined?
measure of bone density
determined by comparing a persons bone density to that of a healthy 30 yr olds of the same sex
112
Type 1 diabetes mellitus
pancreas does not produce enough insulin
113
Type II diabetes mellitus
body does not respond to the circulating insulin
114
HPA axis (cortisol release pathway)
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
What is the HPA axis regulating in the body?
cortisol levels, which have a direct relation to bone density, much like estrogen
116
Which type of receptor will bind a hydrophobic chemical messenger?
GPCR
117
What is the most important hormone for maintaining metabolic rate?
T4 (thyroxine)
118
How do you calculate BMR?
(ml O2 consumed in 1 minute times 60) (weight in kg)
119
How do BMR & hormone levels look in a thyroidectomized individual?
low thyroid & BMR rates (below 1600)
120
How do BMR & hormone levels look in a hypophysectomized individual?
low thyroid & BMR rates (below 1600)
121
Which ion predominantly affects resting membrane potential?
K+ because the cell membrane is much more permeable to it than anything else
122
Where is an action potential generated?
axon hillock
123
Where is a graded potential generated?
soma & dendrite
124
What is resting membrane potential?
potential difference between the inside & the outside of the cell when cell is not being stimulated
125
What is graded potential?
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
What is an action potential?
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
What is a compound action potential
the net effect of all action potentials in an entire nerve
128
What are the events of an action potential?
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
What is depolarization?
Na+ moves into the cell, membrane potential increases
130
What is repolarization?
K+ moves out of the cell, membrane potential decreases
131
What is a synapse?
point of contact between neurons where communication occurs
site of neurotransmitter release
132
How would an action potential be altered with an increase of stimulus voltage?
increasing stimulus would increase the frequency of action potentials
133
What would happen to neurotransmitter release when extracellular Ca2+ levels were 0?
with no Ca2+ present, Ca2+ channels are closed so there would be no neurotransmitters released from the axon
134
Length tension curve for isometric contraction
-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
Force-velocity curve for isotonic contraction
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
Electrical stimulator
delivered amount & duration of stimulating voltage to muscle via electrodes
137
Mounting stand
includes forces transducer to measure amount of force developed by muscle
138
Oscilloscope
displays stimulated muscle twitch & amount of all the forces developed by the muscle; also used to observe voltage changes
139
Microelectrode
a probe with a very small tip that can impale a single neuron
140
Microelectrode amplifier
measures voltage between microelectromechanical & a reference
141
Stimulator
used to select the stimulus modality
142
Recording electrode wires
used to record voltage changes in the axon
143
Hook electrodes
used to record extracellular voltage changes in the axon
144
Manometer
U-shaped tube containing fluid
145
Spectrophotometer
used to measure the amount of light absorbed or transmitted
146
Dual X-ray absorptiometry bone-density scanner (DXA)
measures vertebral bone density
147
HPLC detector
provides hormone concentration to patient
